WO2006089291A1

WO2006089291A1 - Use of phosphorescent materials for two-dimensional wafer mapping in a chemical mechanical polishing

Info

Publication number: WO2006089291A1
Application number: PCT/US2006/006168
Authority: WO
Inventors: Manish Deopura; Pradip K. Roy
Original assignee: Neopad Technologies Corporation
Priority date: 2005-02-18
Filing date: 2006-02-21
Publication date: 2006-08-24

Abstract

Systems and methods for the determination of the end point in a chemical mechanical polishing process are described. The method involves the use of a luminescent indicator that is selectively affected by a material released from a substrate being polished. The luminescence of the indicator is monitored across the substrate surface to assess the content of the surface in determining the desired polishing end point.

Description

USE OF PHOSPHORESCENT MATERIALS FOR TWO-DIMENSIONAL WAFER MAPPING IN CHEMICAL MECHANICAL POLISHING

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claim the priority benefit of U.S. Patent Application No.

60/654,173 filed on February 18, 2005.

FIELD OF THE INVENTION

[0002] The present invention is in the field of chemical mechanical planarization (CMP) of integrated circuits. More particularly it relates to the use of luminescent compounds for the two-dimensional mapping of the wafer surface during the polishing process. The interaction of a luminescent compound with the material released from the surface of the wafer is used to determine the desired process end point.

BACKGROUND

[0003] Generally, integrated circuit manufacturing requires individual layers of the wafers to be planarized, which is typically done using a process that involves mechanical polishing. Preferably, a chemical is included to react with the surface and provide additional polishing of the surface, as with chemical mechanical planarization (CMP). CMP is used to planarize individual layers (e.g. dielectric or metal layers) during integrated circuit manufacturing, such as in copper barrier polishing, Shallow Trench Isolation (STI) polishing, and polishing of other stacks of dissimilar materials, whether patterned or un-patterned. CMP combines chemical and mechanical action to alter the topography across a dielectric region by using a suitable slurry and a polishing pad. Typically, a layered wafer to be polished is mounted on a substrate carrier head, also referred to as a polishing head, and the surface to be polished is pushed against a rotating polishing pad. The slurry is provided between the polishing pad and the wafer surface. The slurry contains a chemical reactive with the wafer layer, and may also contain abrasive inorganic particles that aid in the mechanical polishing of the chemically modified layer. Alternatively, the abrasive inorganic particles may be contained within the surface of the polishing pad. The pad is typically made of polyurethane material, and provides several functions, such as slurry transport, distribution of pressure across the wafer surface, and removal of reacted products. The polishing head that the wafer is mounted on pushes the wafer surface against the polishing head, providing a controllable pressure. The rate of removal of material from the wafer surface is dependent on several factors, such as concentration of abrasive particles, concentration of reactive chemicals, and the coefficient of friction (f) at the pad/slurry/wafer interface. A desireable CMP process results in a finished and planar wafer surface. The end point of the process is the particular point at which the process should be stopped in order to provide the desired surface to the integrated circuit. Common problems in achieving the desired end point involve non-uniformities such as edge effects due to a different rate of polishing at the edge of the wafer relative to the center. End pointing is important in reproducibly providing suitable wafers and remains a major challenge in CMP processing.

[0004] Several methods of end point detection are known, including use of ultrasonics, mechanical resistance measurements, electrical impedance, wafer surface temperature, eddy current and friction measurements, and optical measurements using a localized area window. These methods typically use a change in thickness, a change in the surface, or a change in the material being removed from the surface as a parameter to determine the process end point. For example, US patent 6,280,289, measures the light reflected off of the wafer surface through a window in the polishing pad. The intensity of the reflected light is used to monitor changes in the surface of the wafer. US patents 6,214,732 and 6,749,483 use measurements relating to the materials released from the surface to assess the state of the process. In both of these patents, the content of the slurry that is used to polish the surface is monitored. In the former, the electrochemical potential of the slurry is measured to assess the presence or absence of metal oxides released from the surface. In the latter, the refraction of the slurry is measured for content of an oxidizing agent such as hydrogen peroxide. In this case, hydrogen peroxide oxidized metal on the surface such that as the amount of metal on the surface is reduced, hydrogen peroxide concentration increases. When the metal surface has been suitably removed, the hydrogen peroxide concentration increases accordingly, and the appropriate concentration of hydrogen peroxide determines the end point.

[0005] In the case of patterned wafers, the end point determination is further complicated by the need to account for desired surface irregularities, such as patterned grooves of metal within a dielectric layer. Ideally, the process end point will provide a wafer thickness that gives the desired surface irregularities. Existing methods may lack sufficient accuracy, or do not take into account localized irregularities in the surface, whether these irregularities are undesirable, such as edge effects, or desirable, such as with patterned wafers. Therefore, a need exists to provide a more accurate end point determination. In particular a method is desirable that can measure across the entire surface of the wafer to provide two-dimensional surface mapping.

BRIEF SUMMARY OF THE INVENTION

As the substrate surface is being polished, material from the surface is released into the slurry. In one instance, the material released may be the same form as the layer deposited on the wafer, a different form than the layer deposited on the wafer, or a combination thereof. In one instance, the surface may be a metal layer and the material released is the metal, metal ions or both the metal and metal ions. The material removed from a layer is the material released into solution, e.g. the metal or metal ions.

[0006] The method provided for detecting the end point of the process utilizes a luminescent material, such as a luminescent compound, present in the slurry during the polishing process. In one instance, luminescent material is included in the slurry that is introduced into the process or it is embedded on the surface of the polishing pad such that it leaches into the slurry, or both, such that sufficient luminescent material is present in the slurry between the polishing pad and substrate surface. In one instance, the luminescent material comprises a compound selected from the group consisting of a fluorescent compound, a phosphorescent compound, a chemiluminescent compound, biochemiluminescent compound and a triboluminescent compound, either singly or in any of the possible combinations of these compounds, hi one instance, the luminescence of the material is affected differently by the material removed from a first, or outer or siirface layer on a substrate than by the material removed from a second layer beneath the outer layer. Material being removed from the outer layer may have no effect on the luminescence of the material, or may reduce the intensity of the luminescence, or may increase the intensity of the luminescence as compared to when the material being removed is absent. In one instance, the level of the increase or decrease will depend on the localized concentration of the material being removed in the solution/slurry, hi one instance, the dependence on localized concentration follows a dose/response curve. In one instance, the dose/response is such that the intensity can be correlated to the concentration of material being removed, for example the dose/response is substantially linear, hi one instance, the dose/response is such that the rate of change in intensity can be correlated to the concentration of the material being removed. In one instance, the response occurs above (or below) a certain threshold concentration but does not significantly occur below (or above) that concentration. As the polishing process continues, the second layer will be exposed and material will be removed from the second layer. The material being removed from the second layer may have no effect on the luminescence of the material, or may reduce the intensity of the luminescence, or may increase the intensity of the luminescence as compared to when the material being removed is absent. Further, the effect of the material removed from the second layer will not have the same effect on luminescence as that removed from the first layer. In one instance, the material removed from the first layer has no effect on the luminescence and the material removed from the second layer either increases or decreases the luminescence. In one instance, the material removed from the first layer increases the luminescence and the material removed from the second layer either has no effect or decreases the luminescence. In one instance, the material removed from the first layer decreases the luminescence and the material removed from the second layer either has no effect or increases the luminescence. In one instance, the first layer comprises a metal and the second layer comprises a metal that is different than the first layer or is a dielectric material. In one instance, the first layer comprises a metal layer and the second layer comprises a nitride or oxide layer, such as a silicon nitride or silicon oxide. In one instance, the metal layer is selected from the group consisting of copper, aluminum and tungsten. In one instance, the metal layer is a copper layer and the second layer is an oxide layer. In one instance, metal ions that decrease the intensity of the luminescence are released from the first layer and material released from the second layer does not affect the luminescence. In one instance, the luminescence decreases as the concentration of metal ions increases. In one instance, the emitted light intensity near a localized area of the substrate surface is related to the amount of metal ions being released from that area and the emitted light intensity can be used to map the first layer content of the surface of the substrate. In one instance, metal ions that increase the intensity of the luminescence are released from the first layer and material released from the second layer does not affect the luminescence. In one instance, the luminescent material does not luminesce in the absence of the metal ions and the intensity of luminescence increase as the metal ion concentration increases. In one instance, the emitted light intensity near a localized area of the substrate surface is related to the amount of metal ions being released from that area and the emitted light intensity can be used to map the first layer content of the surface of the substrate. In one instance, the rate of change in emitted light intensity near a localized area of the substrate surface is related to the amount of metal ions being released from that area and the rate of change in emitted light intensity can be used to map the first layer content of the surface of the substrate. In one instance, the luminescent material comprises a fluorescent or phosphorescent compound. In one instance, the luminescent material comprises a compound that is both fluorescent and phosphorescent. Also provided is a new polishing solution comprising a polishing chemical, an abrasive particle and a luminescent indicator, wherein the emission of light from the luminescent indicator is selectively affected by material released by the first layer of the substrate.

[0007] Further, a new method of determining an end point of a chemical mechanical polishing process comprises detecting the light emitted by a luminescent compound between a polishing pad and substrate surface, wherein the emitted light intensity is dependent on the concentration in the solution or slurry, or on the amount or rate of release, of a material released from a layer on the substrate, such that the detected light can be used to determine the process end point, or to map the layer content on the substrate surface. The layer content on the substrate surface may be used to provide an in process two dimensional map of the substrate surface. In one instance, the method comprises (a) providing (i) a substrate having a surface for polishing, (ii) a polishing pad (iii) a solution comprising a luminescent compound that emits light of emission wavelength or wavelengths, wherein the intensity of emitted light is affected by material released by a first layer of the substrate surface upon polishing and is not affected by material released by a second layer beneath the first layer upon polishing, and (iv) a light detector; (b) contacting the substrate surface with the polishing pad and the solution such that a portion of the solution is between the substrate surface and polishing pad, wherein the substrate is in motion relative to the polishing pad; (c) detecting a sufficient amount of light emitted by the luminescent compound from between the substrate surface and polishing pad at a known position; and (f) correlating the signal from the detector as a function of position to determine the process end point. In one instance, the method provides the polishing pad comprising a region that is substantially transparent to a wavelength of wavelengths of light emitted by the luminescent compound. In one instance, the polishing pad support, such as a platen or backing plate, includes an opening or window that may be aligned with a transparent region of the polishing pad. In one instance, the method provides a polishing pad comprising optical fibers passing through the polishing pad. In one instance, the solution is a slurry comprising abrasive particles and a polishing chemical. In one instance, the luminescent compound is selected from the group consisting of a fluorescent compound, a phosphorescent compound, a chemiluminescent compound, a biochemiluminescent compound, and a triboluminescent compound. In one instance, the luminescent compound is selected from the group consisting of a fluorescent compound and a phosphorescent compound.^' In one instance, the method provides a light source and comprises transmitting luminescent activating light from the light source through the polishing pad to the solution between the substrate surface and polishing pad. In one instance, the method further provides filters that block light from the light source from contacting the detector while permitting detection of a sufficient portion of the light emitted by the luminescent compound, hi one instance, wherein the method provides a polishing pad comprising optical fibers, the optical fibers are configured such that light transmitted from a light source to the solution and light transmitted from the luminescent compound to the detector are transmitted through the same optical fibers. In one instance, the optical fibers are configured such that light transmitted from a light source to the solution and light transmitted from the luminescent compound to the detector are transmitted through different optical fibers. In one instance, the light source is a lamp, such as a UV lamp, hi one instance, the light source is a laser. In one instance, the luminescent compound is a triboluminescent compound activated by frictional energy from the interaction of the substrate surface, polishing pad and slurry particles. In one instance, the luminescent compound is a chemiluminescent compound activated by a chemical agent present in the solution or slurry.

[0008] Another new methods involves determining an end point of a chemical mechanical polishing process, comprising (a) providing (i) a substrate having a surface for polishing, (ii) a polishing solution (iii) a luminescent compound activated by light of excitation wavelength or wavelengths that emits light of emission wavelength or wavelengths, wherein the intensity of emitted light is affected by material released by a first layer of the substrate surface upon polishing and is not affected by material released from a second layer beneath the first layer upon polishing, (iv) a polishing pad comprising a region substantially transparent to light of the excitation and emission wavelengths, wherein the polishing pad is mounted on a platen or backing plate that contains an opening or window that can be aligned with the transparent region of the polishing pad; (vi) a light detector that detects light comprising the emission wavelength(s), and (vii) a processor; (b) contacting the substrate surface with the polishing pad and the polishing solution such that a portion of the polishing solution contains the luminescent compound and is between the substrate surface and polishing pad, wherein the substrate is in motion relative to the polishing pad; (c) transmitting a portion of the light from the light source through the transparent region of the polishing pad aligned with the opening in the platen or backing plate to activate the luminescent compound located between the substrate surface and polishing pad; (d) transmitting a portion of the light emitted from the luminescent compound located between the substrate surface and the polishing pad through the transparent region of the polishing pad aligned with the opening in the platen or backing plate to the detector; (e) detecting the emitted light that is transmitted to the detector; and (f) processing the signal from the detector to determine the process end point. In one instance, the first layer is a metal layer and the second layer is a nitride or oxide layer. In one instance, the metal layer is selected from the group consisting of copper, aluminum and tungsten. In one instance, the metal layer is copper and the second layer is a silicon oxide. In one instance, the luminescent compound is selected from the group consisting of a fluorescent compound and a phosphorescent compound. In one instance, the polishing solution comprises abrasive particles, a polishing chemical, and the luminescent compound. In one instance, the method further comprises providing filters that block light from the light source from contacting the detector while permitting detection of a portion of the light emitted by the luminescent compound. In one instance, the detector is configured in a stationary position below the polishing pad and aligned below the substrate surface. In one instance, the detector rotates with the polishing pad and is aligned below the transparent region of the polishing pad, wherein the transparent region is aligned with the opening in the platen or backing plate. In one instance, the light source is configured in a stationary position below the polishing pad such that a portion of the light from the light source is transmitted to the region between the substrate surface and polishing pad when the transparent region of the polishing pad is aligned with the opening in the platen or backing plate. In one instance, the light source rotates with the polishing pad and is located such that a portion of the light from the light source is transmitted through the polishing pad to the region between the substrate surface and polishing pad when the transparent region of the polishing pad is aligned with the opening in the platen or backing plate. In a preferred instance, the light source is positioned so that it does not block light emitted by the luminescent compound from contacting the detector. In one instance, the the light source comprises a lamp that is located adjacent to one edge of the detector. In a further instance, the light source comprises two lamps located adjacent opposite edges of the detector. In a further instance, the light source comprises a lamp that is located adjacent to each edge of the detector. In a further instance, a filter is provided, wherein the filter is configured between the lamp and detector such that light emitted by the lamp does not contact the detector, wherein the filter does not block light emitted by the luminescent compound from contacting the detector. In one instance, the processed signal is used to determine the end point of the polishing process. In one instance, the processed signal is used to provide a two dimensional map of the substrate surface with respect to the content of the first layer.

[0009] Another new method involves determining an end point of a chemical mechanical polishing process, comprising (a) providing (i) a substrate comprising a surface copper layer' and an oxide layer beneath the copper layer, (ii) a slurry comprising abrasive particles, a polishing chemical, and a phosphorescent compound activated by light of excitation wavelengths that emits light of emission wavelengths, wherein the intensity of the emitted light is increased or decreased by the copper ions released from the copper layer upon polishing, and wherein the intensity of the emitted light is not affected by material released from the oxide layer upon polishing, (iii) a polishing pad comprising a region substantially transparent to light of at least some of the excitation wavelengths and at least some of the emission wavelengths, wherein the polishing pad is supported by a platen or backing plate having an opening that can be aligned with the transparent region of the polishing pad, (iv) a light source that emits light comprising excitation wavelengths, (v) a light detector that detects light comprising emission wavelengths, and (vi) a processor, (b) contacting the substrate surface with the polishing pad and the slurry such that a portion of the slurry is between the substrate surface and polishing pad, wherein the substrate is in motion relative to the polishing pad, (c) activating the phosphorescent compound with the light, (d) transmitting a portion of the light emitted by the phosphorescent compound located between the substrate surface and polishing pad through the transparent region of the polishing pad aligned with the opening in the platen or backing plate to the detector, (e) • detecting a sufficient amount of the transmitted light; and (f) processing the signal from the detector to determine the process end point. In one instance, the processed signal provides a two-dimensional map of the copper content of the substrate surface.

[0010] Another new method involves determining an end point of a chemical mechanical polishing process, comprising (a) providing (i) a substrate comprising a surface copper layer and an oxide layer beneath the copper layer, (ii) a slurry comprising abrasive particles, a polishing chemical, and a phosphorescent compound activated by light of excitation wavelengths that emits light of emission wavelengths, wherein the intensity of the emitted light is increased or decreased by the copper ions released from the copper layer upon polishing, and wherein the intensity of the emitted light is not affected by material released from the oxide layer upon polishing, (iv) a polishing pad comprising optical fibers, (v) a light source that emits light comprising excitation wavelengths, (vi) a light detector that detects light comprising emission wavelengths, and (vii) a processor, (b) contacting the substrate surface with the polishing pad and the slurry such that a portion the slurry is between the substrate surface and polishing pad, wherein the substrate is in motion relative to the polishing pad, (c) transmitting light from the light source through the optical fibers to activate the phosphorescent compound, (d) transmitting a portion of the light emitted by the phosphorescent compound located between the substrate surface and polishing pad through the optical fibers to the detector, (e) detecting a sufficient amount of the transmitted light; and (f) processing the signal from the detector to determine the process end point. In one instance, the processed signal provides a two-dimensional map of the copper content of the substrate surface.

[0011] More than one luminescent material may be present in the solution during the polishing process. Each luminescent material present may be selective for indicating the different layers of the substrate. In one instance, a first luminescent material interacts with a first layer material to affect the intensity of light emitted and a second layer has no effect or an opposite effect on the first luminescent material, a second luminescent material interacts with a second layer material to affect the intensity of the light emitted and the first layer has no effect or an opposite effect on the second luminescent material. In one instance, the first luminescent material emits light at a sufficiently different wavelength from the second luminescent material, such that the two light emissions are readily distinguished by a detector. In this instance, the two light signals are processed to provide a map of the content of the two layers on the surface -of the substrate. The system could be similarly designed with three luminescent materials for selective detection of three layers, where each material emits light of sufficiently different wavelengths from the others such that the emissions are readily distinguished by a detector. In an alternative instance, different luminescent materials may emit light of similar wavelength but are excited with light of sufficiently different wavelengths such that different light sources, or selective filtering of the same light source, can be used to selectively excite one material over the other. In this instance, the two indicators are not typically detected simultaneously, and the light emission is correlated with the timing of the excitation light in order to distinguish the two layers. In one instance, the same light source is used to excite each indicator. In one instance, a different light source is used to excite each indicator.

[0012] Also provided is a new polishing apparatus and/or system. In one instance, the invention includes an apparatus for chemical mechanical polishing of a substrate comprising a rotatable platen optionally having an opening; a polishing pad mounted on the platen, wherein the polishing pad comprises either optical fibers or a transparent region that can be aligned with the opening in the platen; a rotatable, vertically movable substrate carrier head; a slurry dispenser, a reservoir containing a slurry, wherein the slurry comprises a polishing chemical and a fluorescent or phosphorescent compound that emits light of emission wavelengths wherein the intensity of the emitted light is affected by a material released by the substrate surface during polishing; abrasive particles, wherein the abrasive particles are either contained within the slurry, embedded on the polishing pad surface, or both contained within the slurry and embedded in the polishing pad surface; a light source that emits light comprising excitation wavelengths of the fluorescent or phosphorescent compound; a detector that detects light of emission wavelengths; and a processor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a schematic cross sectional view of a polishing pad having a window with a light source and detector mounted below the window.

[0014] FIG. 2 is a schematic cross sectional view of a polishing pad containing optical fibers.

[0015] FIG. 3 is a schematic cross sectional view of a polishing pad having a window with a light source and printed detector mounted underneath the pad below the window. DETAILED DESCRIPTION

[0016] Determining the end point of a process for planarizing a substrate, such as an integrated circuit wafer, is particularly challenging. The present invention provides, in one instance, a sensitive, selective, reliable method for the in process mapping of the substrate surface in order to provide accurate end point determination for the polishing of the substrate. The methods of the invention can be applied, for example, to known polishing systems as described in U.S. Patent Nos. 6,280,289 and 6,179,709, and can be applied to similar systems or any system where the solution between a polishing pad and a substrate can be optically monitored. In addition to mapping the composition of the substrate surface, the methods of the invention can be readily adapted to monitor the distribution of the solution between the polishing pad and substrate during a polishing process. While the method is typically applied to integrated circuit processing, it is also applicable to processing of nano-composites, MEMs, Large Area Displays, and other substrates. The method has advantages whether the substrate is patterned or unpatterned, and is particularly useful for patterned semiconductor wafers as it provides a real time two-dimensional surface composition map of the wafer.

[0017] The present invention may be used in a mechanical polishing process, and is particularly useful in a CMP process. While not intending to limit the methods of the invention, it is generally described herein as used in a CMP process, and it can be readily adapted to other methods as would be apparent to one of skill in the art, including those methods discussed herein. The present invention includes a suitable CMP device that provides in process adjustment of the polishing rate incorporating feedback from the two-dimensional mapping of the wafer surface. The CMP process as adapted to the present invention includes the polishing of a wafer surface using a polishing pad, a polishing solution, abrasive particles, a luminescent indicator, an activator of the luminescent material, and mechanical devices that provide the desired contact and relative motion between the polishing pad and wafer surface. For example, a suitable CMP device includes a polishing pad mounted on a rotating platen and a wafer that is mounted on a polishing head which may also rotate. Alternatively, the polishing pad may be a linear driven sheet. The polishing head may be held in place by a chuck, which is connected to, for example, a drive shaft that can provide rotation of the polishing head. The drive shaft can move up and down as well in order to push the rotating wafer onto the polishing pad to provide the necessary contact and relative motion between the surface of the wafer and the polishing pad. In some instances, the drive shaft may optionally move laterally in order to move the wafer surface across the polishing pad surface.

[0018] The device also includes a supply port to introduce the polishing solution, or slurry, onto the polishing pad, which then distributes the solution to the interface of the polishing pad and substrate surface. Any or all of the abrasive particles, luminescent indicator, and, as needed, the activator of the luminescent indicator are optionally included in the polishing solution. Alternatively, any or all of the abrasive particles, luminescent indicator and, as needed, the activator of the luminescent indicator may be embedded in the polishing pad, for example on the surface of the polishing pad such that they are sufficiently released into the polishing solution during the polishing process. It is also possible to introduce either or both of the luminescent indicator and activator of the luminescent indicator, as needed, through a separate supply port. Typically, the abrasive particles, luminescent indicator, and, as needed, the activator of the luminescent indicator are included in the polishing slurry and delivered through a supply port. The supply port may be part of a dispensing arm, or may be integral to another part of the system, such as a central port within the platen that dispenses slurry through the polishing pad to the polishing pad surface, such as described in U.S. Patent Number 6,280,297.

[0019] The polishing head may also include a number of small pressure membranes directly in contact with the back of the wafer. Each membrane encloses a chamber that can be selectively pressurized or de-pressurized to change the force applied to the back of the wafer. For example, a membrane array comprising a series of chambers are connected to a grid of microvalves that can be used to regulate the pressure within each chamber. A fluid, such as a gas, liquid, or gel, can be injected or removed from each chamber independently. Such an array of microvalves and chambers can be controlled by a processor based on feedback from the in process monitoring of the wafer surface. This can be done in localized regions such that the friction between a region of the polishing pad and wafer surface can be regulated independently, or as a function of the pressure applied to adjacent or other regions of the polishing pad. This allows for the regulation of the polishing rate at different regions of the wafer surface. The area that can be differentially affected by such a feedback system depends to some extent on the properties of the substrate, and a feedback mechanism can generally be used to differentiate the polishing rate of an approximately 1 cm² or larger area. The two-dimensional mapping of the wafer surface composition as a wafer or wafer surface is being polished can be used to provide feedback to the pressurized membranes, adjusting the polishing rate in a specific region as needed based on the surface map.

[0020] The device also includes a means for activating the luminescent material as well as a detector for detecting the light emitted by the luminescent material. For example, if the luminescent material is fluorescent or phosphorescent, the device includes a light source that emits light comprising a desirable wavelength for activating the material. Possible light sources include lasers, lamps, or any light source that provides a suitable wavelength or wavelengths of light. If the luminescent material is chemically activated, the reagents needed to activate the luminescent material can be introduced with the slurry, independently of the slurry, and/or can be incorporated into the surface of the polishing pad so that it is released into the solution during the polishing process. In this case, the means for activating is an appropriate chemical added to the pad or slurry. Alternatively, the luminescent material may be mechanically activated by the frictional energy of the polishing process, such as from the abrasive particles between the polishing pad and wafer surface. In this case, the frictional energy from the abrasive particles and relative motion between the polishing pad and substrate provides the means for activating the luminescent compound. The device also includes a detector for detecting the light emitted by the luminescent material, and a data processor that correlates the detected light to the position relative to the substrate surface, such that the signal can be correlated to a two-dimensional map of the wafer surface. The device may be a point detector, such as a photo-multiplier tube, where the detected light can be correlated with the position on the substrate surface. Alternatively, the detector may differentiate the light from across the substrate surface, such as a charge-coupled device, where the differentiated signal from the device is correlated to the position on the substrate surface. Further, the device includes the necessary connections, controllers, data processors, etc., readily available and known to those of skill in the art, to provide the necessary controls, signal processing and feedback. Such systems will correlate the excitation and emission data with system process parameters in order to correlate the light signals with the position on the substrate surface in order to map the substrate surface composition. The system also may provide the necessary feedback to other parts of the process, such as localized pressure applied to regions of the wafer. [0021] Three features can provide in process mapping of the wafer surface during CMP.

Firstly, the introduction of a luminescent material that acts as an inidicator to monitor the polishing process. Secondly, a means for activating the luminescent material. Thirdly, a detection device and processor that can map the signal across the surface of the wafer. The two- dimensional mapping can provide feedback to the system in order to stop the polishing process at the appropriate time. It is also possible to use the in process mapping of the surface to provide feedback to, for example, a system of membranes contacting the back of the wafer that can be used to locally adjust the polishing rate on the surface of the wafer. This feedback from the mapped signal across the wafer surface allows for suitable adjustment of the polishing rate at a desired location on the wafer. The luminescent indicator system may also be adapted to monitor the slurry distribution between the polishing pad and substrate surface, and the polishing rate can be generally or locally adjusted during the process depending on the slurry distribution.

[0022] In order to provide an appropriate indication of the condition of the wafer surface at a particular location across the surface, a luminescent material sensitive to the nature of material being released by a substrate surface can be used. While such a luminescent material may be a particular compound, it is not limited to a compound, per se, as a luminescent compound may be contained within or attached to additional material, such as a matrix or particle. As such, a luminescent material may also be referred to as a luminescent indicator or a luminescent compound, with the understanding that luminescent compound, material, or indicator may be used generally to mean a substance or material that is or includes a luminescent compound. Luminescent compounds may be light activated, such as a fluorescent or phosphorescent compound, or activated by chemical, biochemical or crystallographic changes, the motion of subatomic particles, or radiation-induced excitation of an atomic system.

[0023] Typically, the luminescent compound must be selectively sensitive to material released from one layer of a wafer as compared to other layers. Such a luminescent compound may be suitably selected for a variety of polishing processes, such as polishing by mechanical means only, in chemical mechanical polishing, or related methods. Using CMP as an example, such as in a damascene process, a first layer of metal, such as copper, aluminum, tungsten, or other suitable metal, may be deposited over a second layer of dielectric material, such as a silicon nitride or oxide, where the dielectric layer contains patterned grooves. The end point requires removal of the metal from the surface to expose the dielectric while leaving the desired metal pattern in the grooves. As the surface is polished, the chemical interactions with the slurry result in the release of metal ions. As polishing continues, the second dielectric layer is exposed, resulting in the release of silicon nitride or oxide from the dielectric layer. A suitable luminescent compound is selectively either activated or quenched by the metal ions relative to the nitride or oxide. Further, the luminescent compound is preferably insensitive to other components of the system at the interface of the polishing pad and substrate surface. Upon activation, the luminescent compound will emit a baseline intensity of light, where the intensity is substantially unaffected by background materials, such as the abrasive particles and chemicals present in the slurry. The intensity is either substantially unaffected by material released from the second layer of dielectric material or the material released from the second layer may affect the intensity in a direction opposite that of the material released from the first layer. The luminescence intensity is sensitive to the concentration of metal ions in solution, such that the intensity either increases or decreases as a function of metal ion concentration. This dependence of luminescence intensity on metal ion concentration can either follow a dose/response curve, or may be an on/off situation, e.g. where the dose/response is essentially a step function where luminescence occurs above (or below) a certain threshold concentration and is turned off below (or above) that concentration. In one instance, the luminescent compound may emit a high intensity baseline that is significantly reduced with increasing metal ion concentration. In this case, the material released from the second layer may have no effect, or may act to increase the intensity. Alternatively, the luminescent compound may emit a low intensity baseline that is significantly increased with increasing metal ion concentration. In this case, the material released from the second layer may have no effect, or may act to decrease the intensity. In either case, the light emitted by the luminescent compound is highly sensitive to concentration of the metal ion. As the metal ion concentration will vary depending on the nature of the material being released from the surface of the substrate, the intensity of light emitted across the surface of the substrate will vary, indicating where the surface has been polished to the dielectric layer and where the metal grooves remain. For example, in the case where the luminescent compound intensity increases with metal ion concentration, substrate surface areas where the metal has been removed will no longer release metal ions. The localized metal ion concentration will be very low and little or no light will be emitted from those areas. Areas where metal grooves remain will continue to release metal ions such that the localized metal ion concentration adjacent the grooves will be high and relatively high intensity of light will be emitted from those areas. The light can be monitored across the surface of the wafer and compared to the desired groove pattern in order to determine the end point of the process. The detection across the surface wafer is provided by a suitable detector, where the detector may comprises a grid or sufficiently large area so that it can discriminate light at one spot from light or absence of light at an adjacent spot or region. Detectors such as charge-coupled devices, or array detectors can provide such discrimination. The pattern of emitted light will match the desired groove pattern at the desired end point. In the case where the luminescent compound intensity decreases with metal ion concentration, the opposite pattern will result, where the pattern of emitted light will represent the exposed dielectric and the grooved metal pattern will be the areas of little or no light. While the example described above applies to a first metal layer and second dielectric layer, the method may be applied to any two layers, where the luminescent materials are selected to indicate material being released from one of the layers selectively, without interference from the other layer or from other, materials used in the process. Also, while the example describes a CMP process where the material released from the surface is in a different form than the surface itself (e.g. metal ions released from a metal surface), the method may be applied to a process that does not include the chemical reaction, such as a mechanical polishing process. In this instance, the material released from the surface is in the same form as the surface (e.g. fine metal particles released from a metal surface) such that the indicator is sensitive to the materials released, e.g. the concentration of fine metal particles affects the luminescence. In this instance, the surface material may result in some background signal which is preferably factored into the results. When metal patterns are desired, this background would not be a factor as the luminescent indicator signal will only result from those regions still containing metal. A luminescent indicator may also be used to monitor the distribution of slurry between the polishing pad and substrate surface. In this instance, an indicator is used that is not affected by any components of the system, such as slurry contents. The luminescent intensity will be dependent on the distance between the substrate surface and polishing pad at any given region. For example, a region where substrate surface and polishing pad are very close will contain less luminescent indicator while a region where the substrate surface and polishing pad are further apart will contain more luminescent indicator, such that the intensity of light from a given area can be correlated to the distance between the substrate surface and polishing pad. The polishing rate or slurry content can be appropriately adjusted across the surface of the substrate. [0024] More than one luminescent material may be present in the slurry during the polishing process. Each luminescent material present is preferably selective for indicating different layers of the substrate. For example a first luminescent material may interact selectively with a first layer material relative to a second layer as discussed above while a second luminescent material may interact selectively with a second layer material, similar to the discussion above. In this case, one material is an indicator for the material released from a first layer while the other is an indicator for the material released from the second layer. The first himinescent indicator of the first layer emits light at substantially different wavelengths from the second luminescent indicator of the second layer, such that the two light emissions can be readily distinguished by a detector. In this instance, the light source either emits light of suitable wavelengths to excite both indicators, two light sources are used to provide the required wavelengths, or one or both of the luminescent indicators may be activated chemically or by frictional energy as discussed above. Where both luminescent indicators are light activated, the optimal excitation wavelengths for the two indicators may be substantially the same or different. The light emitted by each indicator may be detected simultaneously with a suitable detector that can distinguish the wavelengths of light emitted by the two indicators as well as the location light was emitted from. In this instance, the two light signals provide a map of each material on the surface of the substrate. In another instance, the two luminescent indicators are excited by substantially different wavelengths but emit light of similar wavelengths. In this instance, the two indicators may be selectively excited by different light sources, or selective filtering of the same light source, to provide two substantially non-overlapping ranges of wavelengths. The light emission of the two indicators can be correlated with the timing of the excitation light in order to distinguish the two layers. For example, the slurry can be alternately excited by the two wavelength ranges with the detector signal differentiating the signal based on excitation light. Systems can be similarly designed with three luminescent materials for selective detection of three materials, where each material is distinguished by the luminescent indicator, either by differences in the excitation wavelength, or differences in the emission wavelengths. Further, one of the luminescent indicators in a multiple indicator system may be selected to monitor the slurry distribution. As discussed above, this indicator will not be affected by any components of the system or slurry. The excitation and emission of this indicator is detected and distinguishable from the layer selective indicator as discussed herein above. [0025] Several options are available for the luminescent material. Luminescent compounds that do not require light activation may be provided, such as chemiluminescenl compounds that can be activated by chemicals or conditions within the slurry (e.g. pH). As an example of a chemiluminescent indicator, luminol (5-amino-2,3-dihydrophthalazine-l,4-dione) is oxidized by hydrogen peroxide in an alkaline solution catalyzed by metal ion (Tyrrell et al., Lab Chip. 4(4): 384-390, 2004). As hydrogen peroxide maybe used as a polishing agent in CMP, this system could be readily adapted such that when metal ions are released from the surface, they catalyze the reaction with hydrogen peroxide and light is emitted in those areas where metal is being removed from the wafer surface. The indicator is present throughout the process and luminescence is turned on only when the metal ion concentration is above a threshold concentration in the slurry. The indicator may be a triboluminescent material that is activated by mechanical energy, such as by friction. Suitable mechanical activation may be provided by the frictional energy of the polishing process, such as from the interaction of the abrasive particles present in the slurry. In one instance, a triboluminescent compound may be bound to the abrasive particle, such that the frictional energy from particle interactions is readily transferred to the triboluminescent compound. A method using either chemiluminescent or triboluminescent compounds provides the advantage that no activating light source is required.

[0026] Luminescent materials that are activated by light, such as fluorescent or phosphorescent compounds, may also be used. Fluorescent compounds absorb light of a fairly high energy, resulting in an excited electronic state. Some of the energy is released by vibrational relaxation within this excited electronic state. The compound can then relax to the electronic ground state, resulting in the emission of light of lower energy than initially absorbed. The fluorescent lifetime is on the order of 10^"9 seconds. In phosphorescent compounds, the excited electronic state (singlet state) can crossover to an excited triplet state by intersystem crossing. This excited triplet state can then relax to the ground singlet state, resulting in emission of light. As this relaxation from a triplet state to singlet state occurs more slowly, phosphorescence lifetimes can be much longer than fluorescent lifetimes, and occur in the range of 10^"7 seconds to as long as seconds or even minutes. Depending on the interaction of the excited electronic states or the emitted light with metal ions, certain fluorescent and phosphorescent compounds are ideal indicators for metal ions. In some instances, metal ions may chelate with the luminescent compound and enhance fluorescence. In some cases, the metal ions may quench the emitted light, such as by absorbing the light or by collisional quenching, where this quenching will depend on the concentration of the metal ions in the region of the luminescent material. In some instances, a metal ion may quench fluorescence while simultaneously enhancing phosphorescence. For example, a particular metal ion may promote intersystem crossing of the excited state of the compound, resulting in an increase of phosphorescence and decrease in fluorescence. Such a system could be used to provide light emissions that can be used to map the wafer surface. When the energy of the fluorescent emission differs from that of phosphorescent emission, the detector can be configured to measure both light emissions simultaneously. As a result, the surface can be mapped with either or both emissions, where the maps for each emission will be mirror images since one is increased and the other decreased as a function of the particular metal ion concentration.

[0027] Fluorescent or phosphorescent compounds are selected for the material released from a layer. For example, suitable compounds and metal ion combinations can be determined to provide a high level of selectivity and sensitivity for mapping a metal layer. Suitable indicators may be found, for example, in the Handbook of Molecular Probes and Research Products, ninth edition (Molecular Probes, Eugene, OR) for a variety of metal ions. For example, phenanthroline based indicators, such as Phen Green fluorescent indicator, can be used to detect the copper ion concentration (Cu²⁺ or Cu⁺) (Kuhn et al., Proc. SPIE-Int Soc Opt Eng 2388:238-244, 1995). Similarly, Fluo-4 and FuraZin-1 appear to be suitable choices for copper detection, as well as calcein (Breuer et al., Am J Physiol 268(6): C1354-C1361, 1995). However, as other metal ions may interfere, these indicators would be used in a system where there are no interfering metal ions present.

[0028] In addition to sensitivity and selectivity for a material to be detected, additional features to consider when selecting a luminescent material to be used are the decay lifetime of the light emission and the strength of the interaction of the material being detected with the luminescent material. The emission lifetime is preferably sufficiently short so as not to generate signal that is not representative of the wafer surface at a specific region and time. When the indicator is quenched by the presence of the material to be detected, this is not an issue as the measurement is directly related to the localized concentration of the material, such as the metal ion. The detected light will only appear where there is little or no quenching material, and provides a direct measurement of the nature of the wafer surface. This is not necessarily the case when the material to be detected stimulates the light emission. For example, when a metal ion stimulates phosphorescence, the lifetime of emission can be on the order of seconds or even minutes. Once the phosphorescent compound has been stimulated in the presence of the metal ions, the light emission continues whether or not the local metal ion concentration remains at a level necessary to stimulate further emission. This may result in high interfering background and a less accurate measure of the surface map. Consider, for example, a polishing head that is moving at several hundred cycles per second relative to the polishing pad. The surface of the wafer may be irradiated to stimulate phosphorescence with a lifetime on the order of seconds. When the light emission is measured over time, the surface will have changed considerably over the lifetime of emission such that light is still being emitted by compound that is no longer in a region of material that stimulated the emission. Thus, for this type of detection, the emission lifetime is preferably suitably short, such as on the order of less than 10^"4 seconds, also less than about 10^"5 seconds. Similar issues are preferablyconsidered concerning the interaction of the material to be determined and the luminescent material. If there is a strong affinity between the luminescent material and the material to be determined, this has to be taken into consideration. For example, some fluorescent of phosphorescent compounds can chelate metal ions, where the chelated metal ion affects light emission of the compound. If the interaction between the two is strong, for example if the dissociation constant is in a μM range or lower, the interaction may not be dependent on the local concentration of metal ions. For example, a compound may have a high level of fluorescence when it chelates metal ions in an area of high concentration. The chelating of metal ions maybe sufficiently strong such that even if the metal ion concentration has decreased significantly, or the compound has migrated to a region of low metal ion concentration, sufficient metal remains chelated such that an erroneous positive signal is generated that is not representative of the actual metal ion concentration. As such, it is prefereable that the dissociation constant for the interaction of indicator with the material to be detected is on the order of 1 mM or higher. In one instance, the indicator is selected to have substantially no affinity for the material to be detected, but interacts based on random migration and collision such that any affect that the material has on the indicator is directly related to the localized concentration of the material to be detected.

[0029] The luminescent materials discussed above may be introduced into the system by several methods. One possibility is to include the luminescent compound in the slurry being delivered to the polishing pad. Another possibility is that the CMP device includes a second supply port for delivery of the luminescent compound to the slurry. The luminescent compound could also be embedded on the surface of the polishing pad such that it is continuously released during the process. The luminescent compound may be introduced as a solution of the compound itself. The luminescent compound may also be introduced within a matrix, such as within a particulate or similar matrix. For example, the compound may be bound to the surface of a particulate material such that the material released from the substrate can readily interact with the luminescent compound on the particulate material. As one example of this, the luminescent indicator may be bound to the surface of the abrasive particles in the slurry. A particular aspect includes a triboluminescent compound bound to the surface of the abrasive particles such that the interaction of the abrasive particles with each other, the polishing pad, and/or the substrate surface provides frictional energy to activate the luminescent compound. Alternatively, the compound may be contained within a particle or similar matrix rather than on the surface. In this case, the matrix may be readily permeable to the material released from the substrate such that it interacts with the luminescent compound. It is also possible that the particle or matrix is not permeable to the material released from the substrate, but the released material surrounding the particle or matrix is able to absorb or quench the light emitted by the luminescent compound. The particle or matrix is transparent to both the light that is emitted by the compound and to the light required to activate the compound. Similarly, compounds or materials necessary to activate luminescent materials that are not light activated may be introduced into the system by inclusion in the slurry or in the solution containing the luminescent compound or material, or maybe embedded on the surface of the polishing pad such that it is continuously released during the process. Alternatively, the activating agent may be added through its own supply port. In one method, any agents necessary to activate the luminescent compound are added in the same solution as the luminescent compound. In a preferred method, a luminescent compound and any agents necessary to activate the compound are contained within the slurry added to the polishing pad.

[0030] Another aspect of the present invention is to provide a system for activating the luminescent material. As discussed above, the activation of chemiluminescent or triboluminescent materials may be achieved by suitably modifying the system such that either the slurry contains an activating agent, or the activating agent is separately introduced. For light activated compounds, a light source is needed to activate the compounds in the slurry that is contacting the area that is to be mapped. The light source will provide light of suitable wavelength and intensity to excite the fluorescent or phosphorescent compounds. Possible light sources include, but are not limited to, a lamp that generates light of a broad spectrum of wavelengths, such as a UV lamp, or a laser that provides a suitable wavelength. A light source providing a range of wavelengths can be used to activate a variety of indicator compounds, such that one light source can be used for optional indicators or more than one indicator in the process. Alternatively, where a system is designed for a specific compound, the light source can be chosen to provide light in a narrower range for the specific wavelength that is required, such as a specific wavelength provided by a laser. Similarly, in multiple indicator systems, multiple lasers may be used to provide a suitable wavelength for each indicator as needed based on their excitation spectra. In order to deliver the light to the slurry at the substrate surface, the polishing pad may comprise a region transparent to the desired wavelengths through which the light can be directed to irradiate the slurry. The transparent region may be a window in the polishing pad, or the entire polishing pad may be suitably transparent. Suitable polishing pads are described, for example, in U.S. Patent Nos. 5,893,796, 6,171,181, and 6,179,709. In addition to a transparent region in the polishing pad, the platen or backing plate supporting the polishing pad will have a suitable window or opening. One example of a suitable system is shown in Figure 1 , where the light source is mounted within the platen, either below the window in the polishing pad and opening in the platen such that it rotates with the window, or stationary and positioned directly below the polishing head such that light passes through the window and opening in the platen as it traverses the substrate surface. Alternatively, the light source is stationary and configured such that the area below the platen is evenly irradiated so that light of roughly even intensity is transmitted through the window and backing support/platen as the polishing pad window traverses the substrate surface. The transparent window region of the pad is of suitable size to monitor at least a portion of the substrate surface. For example, a small area window, such as square or rectangle of roughly 1-10 mm per side, or a circular window of roughly 1-10 mm diameter, can move across the substrate surface to provide data across the substrate that can be averaged to assess the overall substrate surface. Alternatively, the window can be large enough to encompass most or all of the substrate surface, such that the signal at any given time can be correlated to an overall picture of the surface or a significant portion thereof. The necessary processing of the signals in relation to the position of the substrate surface can be determined from known parameters, such as the rotation rates of the two heads and the relative window position as the signal is detected. The polishing pad and substrate may include sensors that indicate their positions relative to each other and the transparent region. The activation and light detection is then correlated with these parameters to match the detected light with the location on the surface of the substrate, providing the two-dimensional map of the surface. Processing of optical signals in such systems is known to those of skill in the art, such as described, for example, in U.S. Patent Number 6,280,289.

[0031] In another aspect, the polishing pad comprises a series of optical fibers through which the light can be directed. An example of this is shown in Figure 2. Such pads may be manufactured by modifying known methods of pad production. For example, a process for making pads by injection of liquid polymer into molds or casts can be modified by positioning a sufficient portion of the optical fibers within the mold or cast prior to injecting the liquid polymer. Further, the optical fibers will extend out of the formed pad, and maybe bundled and optically connected to a suitable detector. The orientation of the optical fibers could be similar to that of the window discussed above, i.e. it could provide irradiation of a narrow section that scans across the substrate surface and the signal correlated with the position of the surface. Alternatively, the optical fibers could be positioned evenly throughout the polishing pad such that the wafer surface is constantly being irradiated. Ln this instance, most or all of the substrate surface can be continuously monitored to provide a map of the surface composition at any point in time.

[0032] In order to detect the light emitted by the luminescent indicator, a suitable detection system is provided. For example, in Figure 1 discussed above, where the polishing pad comprises a transparent region through which activating light is directed, the emitted light can pass back through the same region into a suitable detector. Similarly, such a window could be used in the absence of a light source for those luminescent indicators that do not require light activation. In either case, a suitable detector can be mounted within the system below the pad window and platen/backing opening such that it rotates with the platen and continuously collects light of the desired wavelength coming through the window, or the detector can be stationary, located below the area of substrate surface such that as the window passes over the detector, light from the area below the substrate surface is transmitted through the window and platen/backing opening to the detector. When there is both a light source and a detector mounted in the platen, the detector will preferably have optical filters to only collect light of appropriate wavelength coming from the luminescent material. As the excitation wavelength is typically considerably different from the emission wavelength, the light source and detector combination can be suitably adjusted to deliver light of a specific wavelength range and to filter out all but a sufficient amount of the emitted wavelengths to the detector. The light source may be mounted along the sides so as not to physically block the light emitted from the luminescent indicator from reaching the detector, as shown in Figure 1. The detector itself may be readily selected from available systems known in the art. Alternatively, a detector such as a silkscreen detector or printed detector can be mounted underneath the polishing pad below the substrate surface, as shown in Figure 3. When more than one luminescent indicators emitting different wavelengths are used, the detector can distinguish between the different signals. In the example comprising optical fibers within the polishing pad, the light emitted by the luminescent material can be collected through the same fibers, or another array of fibers may be used to collect the emitted light. When more than one luminescent indicators emitting different wavelengths are used, the detector can distinguish between the different signals in the same fiber, or the different signals could be collected through different fibers, e.g. suitable wavelength filters can be used to collect the desired signal through a given fiber. The spacing of the detection fibers will provide the necessary resolution of the surface map. When more than one luminescent indicator is used in which the emitted light can not be easily distinguished but the excitation wavelengths are substantially different, the excitation light may be alternated between the desired wavelengths and the response signal is correlated to the excitation signal based on the timing of the signal. In this instance, the same detection system may be used to collect the signal.

[0033] In another aspect of the invention, the detection system provides feedback to the overall polishing process. The signal that is generated is correlated with the position at the surface of the wafer to provide a two-dimensional map of the nature of the wafer surface. The desired pattern of the wafer can be used to determine the desired end point map, and the feedback from the detection system can be used to stop the process accordingly. In a further aspect, the feedback can be used to identify areas on the surface of the wafer that require a variation in the polishing rate relative to other areas on the surface. The polishing rate of the surface is dependent on, among other factors, the coefficient of friction at the polishing pad/wafer surface interface. The frictional coefficient is dependent on the relative rate of motion between the polishing pad and substrate surface and the relative amount of force of the substrate surface against the polishing pad surface. As such, the polishing rate may be adjusted during the process by a change in the force pushing the wafer against the polishing pad. This force is generally provided by a mechanical force driving the polishing head on which the wafer is mounted down towards the polishing pad. Additional force may be provided to the wafer using a series of pressurized membranes within the polishing head in contact with the back of the wafer that can selectively push down on or reduce pressure on specific regions of the wafer. Figure 4 indicates a system in which the polishing head comprises a series of membranes on which the wafer is mounted. The membranes contact the back of the wafer and can be adjusted to provide areas of varied pressure across the dimensions of the wafer. The membranes may enclose a chamber for which the pressure can be adjusted, for example by adjusting the air pressure within the chamber. As the membrane pressure is adjusted, the force pushing the wafer against the polishing pad is adjusted accordingly at a selected location of the wafer. This series of pressurized membranes can be configured to receive feedback from the detection system in order to adjust the pressure accordingly. For example, the detection system may indicate that certain portions of the wafer need to be polished at a faster rate relative to other portions in order to provide the desired end point. The feedback to the pressure membranes indicate which membranes need to be pressurized or de-pressurized to provide the appropriate force to either increase or decrease the polishing rate of a specific region of the wafer surface. Such a system can provide localized polishing within an area of about 1 cm² or larger.

[0034] The methods and systems discussed herein provide in process two-dimensional mapping of a substrate surface that can be readily adapted or combined with any known systems, and the invention is not intended to be limited to the examples herein. The necessary system interconnections, such as power connections, electronics, processors, computers, controllers and the like can be suitably engineered by those skilled in the art. As such, the present invention includes any polishing system adapted to include luminescent indicators, an activator of the luminescent indicator, such as a light source, chemical, or physical agent, indicator light emission detector and data processor, process feedback controls, and optionally a system of membrane bound chambers and feedback controls that provide adjustable pressure to the back of the substrate to adjust the polishing rate at the surface of the substrate. All references cited herein above are hereby incorporated by reference in their entirety.

[0035] Disclosed above are various features that may be combined into the following examples of various devices and methods, which examples of course supplement the disclosure and do not limit the scope of the invention: 1. A method for detecting an end point of a chemical mechanical polishing process, comprising:

(a) providing a substrate, having a surface, for chemical mechanical polishing;

(b) providing a polishing pad having a polishing surface;

(c) providing a liquid;

(d) providing a luminescent compound;

(e) contacting the substrate surface with the polishing pad and the liquid such that a portion of the liquid is between the substrate surface and polishing pad, wherein the substrate is in motion relative to the polishing pad;

(f) delivering the luminescent material capable of emitting light to the liquid; and

(g) detecting emission from the luminescent material to determine the process end point;

2. The method according to paragraph 1 wherein an intensity of the emission from the luminescent material is detected.

3. The method according to paragraphs 1 or 2 wherein the luminescent material is at least one material selected from a group consisting: a fluorescent, a phosphorescent, a chemiluminescent, a biochemiluminescent, and a triboluminescent material.

4. The method according to any of the above paragraphs further comprising illuminating with a light source to illuminate light activated luminescent material.

5. The method according to any of the above paragraphs further comprising detecting the emission from the luminescent material using a detector.

6. A method according to any of the above paragraphs further comprising a processor to correlate the emission to the process end point.

7. The method according to any of the above paragraphs wherein the luminescent material is delivered to the liquid by being released from the polishing pad during chemical mechanical polishing. 8. The method according to any one of paragraphs 1-6 wherein the luminescent material is contained in the liquid provided for chemical mechanical polishing.

9. The method according to any one of paragraphs 1-6 wherein the luminescent material is delivered to the liquid by being released from the substrate during chemical mechanical polishing.

10. The method according to any of the above paragraphs wherein the liquid contains a reactive material, wherein the emission results from the luminescent material reacting with the reactive material present in the liquid during chemical mechanical polishing.

11. The method according to any one of paragraphs 1-9 wherein the emission results from the luminescent material reacting with the substrate surface during chemical mechanical polishing.

12. The method according to any one of paragraphs 1-9 wherein the emission results from the luminescent material reacting with the polishing pad during chemical mechanical polishing.

13. The method according to paragraph 10 wherein the reactive material contained in the liquid is released from the substrate and delivered to the liquid during chemical mechanical polishing.

14. The method according to paragraph 10 wherein the reactive material contained in the liquid is released from the polishing pad and delivered to the liquid during chemical mechanical polishing.

15. The method according to paragraph 10 wherein the reactive material is contained in the liquid provided for chemical mechanical polishing.

16. The method according to any one of the above paragraphs wherein the liquid further contains a concentration of material removed from the substrate wherein the emission of the luminescent material is affected by the material removed from the substrate present in the liquid. 17. The method according to paragraph 16 wherein the material removed from the substrate increases the emission.

18. The method according to paragraph 16 wherein the material removed from the substrate decreases the emission.

19. The method according to paragraph 16 wherein the emission is affected by the concentration of the material removed from the substrate present in the liquid.

20. The method according to paragraph 19 wherein the affect is linearly con-elated to the concentration of the material removed from the substrate present in the liquid.

21. The method according to any of the above paragraphs wherein emission occurs at or above a certain concentration threshold of the material removed from the substrate present in the liquid.

22. The method according to any of the above paragraphs wherein emission occurs at or below a certain concentration threshold of the material removed from the substrate present in the liquid.

23. The method according to paragraph any of the paragraphs wherein the substrate is comprised of a first and a second layer.

24. The method according to paragraph 23 wherein material removed from the first layer decreases the emission.

25. The method according to paragraph 23 wherein material removed from the first layer increases the emission.

26. The method according to paragraph 23 wherein the material removed from the first layer does not effect the emission.

27. The method according to any one of paragraphs 23-26 wherein material removed from the second layer decreases the emission. 28. The method according to any one of paragraphs 23-26 wherein material removed from the second layer increases the emission.

29. The method according to any one of paragraphs 23-28 wherein the first layer is a metal.

30. The method according to any one of paragraphs 23-28 wherein the first layer is an oxide.

31. The method according to any one of paragraphs 23-28 wherein the first layer is a nitride.

32. The method according to any one of paragraphs 23-31 wherein the second layer is a metal.

33. The method according to any one of paragraphs 23-31 wherein the second layer is an oxide.

34. The method according to any one of paragraphs 23-31 wherein the second layer is a nitride.

35. The method according to paragraph 32 wherein the metal decreases the emission.

36. The method according to paragraph 33 wherein the oxide decreases the emission.

37. The method according to paragraph 34 wherein the nitride decreases the emission.

38. The method according to paragraph 32 wherein the metal increases the emission.

39. The method according to paragraph 33 wherein the oxide increases the emission. 40. The method according to paragraph 34 wherein the nitride increases the emission.

41. The method according to any of the above paragraphs where in the emission is further used to provide an in process two dimensional map of the substrate surface.

42. A method according to any of paragraphs 5-41 further comprising a transparent region on the polishing pad for transmitting light emitted from the luminescent material to the detector.

43. A method according to any of the above paragraphs further comprising a platen attached to the polishing pad.

44. A method according to paragraph 43 wherein the platen has an opening capable of transmitting light, wherein the opening is aligned with the transparent region of the polishing pad.

45. The method according to any of the above paragraphs wherein the light source is selected a UV lamp.

46. The method according to any of paragraphs 1-44 wherein the light source is a laser.

47. The method according to any of the above paragraphs where in fiber optical cables are used to transmit the emission from the luminescent material to the detector.

48. A method according to any of the above paragraph wherein the luminescent material is a comprised of a first and a second luminescent material.

49. A method according to any of the above paragraphs wherein the first luminescent material reacts with the first layer and the second luminescent material reacts with the second layer. 50. The method according to paragraphs 29, 32, 35 or 38 wherein the metal is selected from a group consisting of copper, aluminum, and tungsten.

51. The method according to any of the above paragraphs wherein the liquid contains inorganic particles.

52. The method according to any of the above paragraphs wherein the liquid contains abrasive particles.

53. The method according to any of the above paragraphs wherein the liquid contains a chemical reactive which reacts with the surface of the substrate.

54. The method according to any of the above paragraphs wherein the luminescent material is both fluorescent and phosphorescent.

55. The method according to any of the above paragraphs wherein the polishing pad is substantially transparent to the emission from the luminescent material.

56. The method according to any of the above paragraphs wherein the emission from the luminescent material provides a two-dimensional map of the copper content of the substrate surface.

57. The method according to any of the above paragraphs wherein two signals from two different luminescent materials provide a two dimensional map of the first and second layers on the substrate.

58. The method according to any of the above paragraphs wherein the substrate further comprises a third layer, wherein three signals from three different luminescent materials provide a two dimensional map of the first, second, and third layers on the substrate

59. The method according to any of the above paragraphs further comprising filtering with a filter the light from the light source while allowing light from the luminescent material to pass. 60. An apparatus for chemical mechanical polishing comprising: a rotateable platen having an opening; a polishing pad mounted on the platen; and a rotateable substrate head; wherein the polishing pad has either a transparent region or an attached optical fiber for transmitting light emitted from the luminescent material;

61. The apparatus of paragraph 60 further comprising a liquid dispenser.

62. The apparatus according to paragraph 60 or 61 further comprising: a reservoir containing a liquid.

63. The apparatus according to paragraph 62, wherein the liquid contains a luminescent material having emission characteristics which depend on material released into the liquid during polishing,

64. The apparatus according to any of paragraphs 60-63 further comprising a detector for detecting light emitted by the luminescent material.

65. The apparatus according to any of paragraphs 60-64 further comprising a processor for correlating the light collected by the detector to determine the process endpoint.

66. A polishing solution comprised of a polishing chemical, an abrasive particle and a luminescent material, wherein the emission of light from the luminescent material is affected by material released from a polishing substrate.

67. The polishing solution of paragraph 66 wherein the luminescent indicator is affected by material released from a first layer of the polishing substrate.

68. The polishing solution of paragraph 66 wherein the luminescent indicator is selectively affected by material released from a second layer of the polishing substrate.

69. A method of determining an end point of a chemical mechanical polishing process, comprising: (a) providing (i) a substrate comprising a surface copper layer, capable of releasing copper ions upon polishing, and an oxide layer beneath the copper layer, (ii) a liquid comprising abrasive particles, a polishing chemical, and a phosphorescent compound activated by light of excitation wavelengths that emits light of emission wavelengths, wherein the intensity of the emitted light is increased or decreased by the copper ions released from the copper layer upon polishing, and wherein the intensity of the emitted light is not affected by material released from the oxide layer upon polishing, (iii) a polishing pad comprising a region substantially transparent to light of at least some of the excitation wavelengths and at least some of the emission wavelengths, wherein the polishing pad is supported by a platen or backing plate having an opening that can be aligned with the transparent region of the polishing pad, (iv) a light source that emits light comprising excitation wavelengths, (v) a light detector that detects light comprising emission wavelengths, and (vi) a processor;

(b) contacting the substrate surface with the polishing pad and the liquid such that a portion of the liquid is between the substrate surface and polishing pad, wherein the substrate is in motion relative to the polishing pad;

(c) activating the phosphorescent compound with the light;

(d) transmitting a portion of the light emitted by the phosphorescent compound located between the substrate surface and polishing pad through the transparent region of the polishing pad aligned with the opening in the platen or backing plate to the detector;

(e) detecting a sufficient amount of the transmitted light; and

(f) processing the signal from the detector to determine the process end point.

[0036] Any of the above combinations may of course have any of the physical, chemical, and/or DMA properties discussed above.

[0037] Although exemplary variations of customized polishing pads have been described, various modifications of the subject pads described can be made without departing from the scope or spirit of what is disclosed herein. Disclosure of various customized polishing pads herein should not be construed to be limited by the specific examples and drawings described above. Moreover, one of skill in the art would realize a variety equivalent customized polishing pads that can be taken from such examples and drawings there from.

Claims

1. A method for detecting an end point of a chemical mechanical polishing process, comprising:

(a) providing a substrate, having a surface, for chemical mechanical polishing;

(b) providing a polishing pad having a polishing surface;

(c) providing a liquid;

(d) providing a luminescent compound;

2. The method according to claim 1 wherein an intensity of the emission from the luminescent material is detected.

3. The method according to claims 1 or 2 wherein the luminescent material is at least one material selected from a group consisting: a fluorescent, a phosphorescent, a chemiluminescent, a biochemiluminescent, and a triboluminescent material.

4. The method according to any of the above claims further comprising illuminating with a light source to illuminate light activated luminescent material.

5. The method according to any of the above claims further comprising detecting the emission from the luminescent material using a detector.

6. A method according to any of the above claims further comprising a processor to correlate the emission to the process end point.

7. The method according to any of the above claims wherein the luminescent material is delivered to the liquid by being released from the polishing pad during chemical mechanical polishing.

8. The method according to any one of claims 1-6 wherein the luminescent material is contained in the liquid provided for chemical mechanical polishing.

9. The method according to any one of claims 1-6 wherein the luminescent material is delivered to the liquid by being released from the substrate during chemical mechanical polishing.

10. The method according to any of the above claims wherein the liquid contains a reactive material, wherein the emission results from the luminescent material reacting with the reactive material present in the liquid during chemical mechanical polishing.

11. The method according to any one of claims 1-9 wherein the emission results from the luminescent material reacting with the substrate surface during chemical mechanical polishing.

12. The method according to any one of claims 1-9 wherein the emission results from the luminescent material reacting with the polishing pad during chemical mechanical polishing.

13. The method according to claim 10 wherein the reactive material contained in the liquid is released from the substrate and delivered to the liquid during chemical mechanical polishing.

14. The method according to claim 10 wherein the reactive material contained in the liquid is released from the polishing pad and delivered to the liquid during chemical mechanical polishing.

15. The method according to claim 10 wherein the reactive material is contained in the liquid provided for chemical mechanical polishing.

16. The method according to any one of the above claims wherein the liquid further contains a concentration of material removed from the substrate wherein the emission of the luminescent material is affected by the material removed from the substrate present in the liquid.

17. The method according to claim 16 wherein the material removed from the substrate increases the emission.

18. The method according to claim 16 wherein the material removed from the substrate decreases the emission.

19. The method according to claim 16 wherein the emission is affected by the concentration of the material removed from the substrate present in the liquid.

20. The method according to claim 19 wherein the affect is linearly correlated to the concentration of the material removed from the substrate present in the liquid.

21. The method according to any of the above claims wherein emission occurs at or above a certain concentration threshold of the material removed from the substrate present in the liquid.

22. The method according to any of the above claims wherein emission occurs at or below a certain concentration threshold of the material removed from the substrate present in the liquid.

23. The method according to claim any of the claims wherein the substrate is comprised of a first and a second layer.

24. The method according to claim 23 wherein material removed from the First layer decreases the emission.

25. The method according to claim 23 wherein material removed from the first layer increases the emission.

26. The method according to claim 23 wherein the material removed from the first layer does not effect the emission.

27. The method according to any one of claims 23-26 wherein material removed from the second layer decreases the emission.

28. The method according to any one of claims 23-26 wherein material removed from the second layer increases the emission.

29. The method according to any one of claims 23-28 wherein the first layer is a metal.

30. The method according to any one of claims 23-28 wherein the first layer is an oxide.

31. The method according to any one of claims 23-28 wherein the first layer is a nitride.

32. The method according to any one of claims 23-31 wherein the second layer is a metal.

33. The method according to any one of claims 23-31 wherein the second layer is an oxide.

34. The method according to any one of claims 23-31 wherein the second layer is a nitride.

35. The method according to claim 32 wherein the metal decreases the emission.

36. The method according to claim 33 wherein the oxide decreases the emission.

37. The method according to claim 34 wherein the nitride decreases the emission.

38. The method according to claim 32 wherein the metal increases the emission.

39. The method according to claim 33 wherein the oxide increases the emission.

40. The method according to claim 34 wherein the nitride increases the emission.

41. The method according to any of the above claims where in the emission is further used to provide an in process two dimensional map of the substrate surface.

42. A method according to any of claims 5-41 further comprising a transparent region on the polishing pad for transmitting light emitted from the luminescent material to the detector.

43. A method according to any of the above claims further comprising a platen attached to the polishing pad.

44. A method according to claim 43 wherein the platen has an opening capable of transmitting light, wherein the opening is aligned with the transparent region of the polishing pad.

45. The method according to any of the above claims wherein the light source is selected a UV lamp.

46. The method according to any of claims 1-44 wherein the light source is a laser.

47. The method according to any of the above claims where in fiber optical cables are used to transmit the emission from the luminescent material to the detector.

48. A method according to any of the above claim wherein the luminescent material is a comprised of a first and a second luminescent material.

49. A method according to any of the above claims wherein the first luminescent material reacts with the first layer and the second luminescent material reacts with the second layer.

50. The method according to claims 29, 32, 35 or 38 wherein the metal is selected from a group consisting of copper, aluminum, and tungsten.

51. The method according to any of the above claims wherein the liquid contains inorganic particles.

52. The method according to any of the above claims wherein the liquid contains abrasive particles.

53. The method according to any of the above claims wherein the liquid contains a chemical reactive which reacts with the surface of the substrate.

54. The method according to any of the above claims wherein the luminescent material is both fluorescent and phosphorescent.

55. The method according to any of the above claims wherein the polishing pad is substantially transparent to the emission from the luminescent material.

56. The method according to any of the above claims wherein the emission from the luminescent material provides a two- dimensional map of the copper content of the substrate surface.

57. The method according to any of the above claims wherein two signals from two different luminescent materials provide a two dimensional map of the first and second layers on the substrate.

58. The method according to any of the above claims wherein the substrate further comprises a third layer, wherein three signals from three different luminescent materials provide a two dimensional map of the first, second, and third layers on the substrate

59. The method according to any of the above claims further comprising filtering with a filter the light from the light source while allowing light from the luminescent material to pass.

60. An apparatus for chemical mechanical polishing comprising: a rotateable platen having an opening; a polishing pad mounted on the platen; and a rotateable substrate head; wherein the polishing pad has either a transparent region or an attached optical fiber for transmitting light emitted from the luminescent material;

61. The apparatus of claim 60 further comprising a liquid dispenser.

62. The apparatus according to claim 60 or 61 further comprising: a reservoir containing a liquid.

63. The apparatus according to claim 62, wherein the liquid contains a luminescent material having emission characteristics which depend on material released into the liquid during polishing,

64. The apparatus according to any of claims 60-63 further comprising a detector for detecting light emitted by the luminescent material.

65. The apparatus according to any of claims 60-64 further comprising a processor for correlating the light collected by the detector to determine the process endpoint.

67. The polishing solution of claim 66 wherein the luminescent indicator is affected by material released from a first layer of the polishing substrate.

68. The polishing solution of claim 66 wherein the luminescent indicator is selectively affected by material released from a second layer of the polishing substrate.

69. A method of determining an end point of a chemical mechanical polishing process, comprising:

(a) providing (i) a substrate comprising a surface copper layer, capable of releasing copper ions upon polishing, and an oxide layer beneath the copper layer, (ii) a liquid comprising abrasive particles, a polishing chemical, and a phosphorescent compound activated by light of excitation wavelengths that emits light of emission wavelengths, wherein the intensity of the emitted light is increased or decreased by the copper ions released from the copper layer upon polishing, and wherein the intensity of the emitted light is not affected by material released from the oxide layer upon polishing, (iii) a polishing pad comprising a region substantially transparent to light of at least some of the excitation wavelengths and at least some of the emission wavelengths, wherein the polishing pad is supported by a platen or backing plate having an opening that can be aligned with the transparent region of the polishing pad, (iv) a light source that emits light comprising excitation wavelengths, (v) a light detector that detects light comprising emission wavelengths, and (vi) a processor;

(c) activating the phosphorescent compound with the light;

(e) detecting a sufficient amount of the transmitted light; and

(f) processing the signal from the detector to determine the process end point.