US20110275288A1

US20110275288A1 - Cmp pad dressers with hybridized conditioning and related methods

Info

Publication number: US20110275288A1
Application number: US13/034,213
Authority: US
Inventors: Chien-Min Sung
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-05-10
Filing date: 2011-02-24
Publication date: 2011-11-10
Also published as: TW201143979A; CN102240973A; TWI440527B

Abstract

The present invention provides CMP pad dressers and methods for dressing or conditioning CMP pads. In one aspect, for example, a CMP pad conditioner is provided. Such a conditioner can include a support matrix, and a plurality of smooth superabrasive particles disposed in the support matrix, where the smooth superabrasive particles are operable to cut large asperities in a CMP pad. The conditioner also includes a plurality of rough superabrasive particles disposed in the support matrix, where the rough superabrasive particles operable to cut slurry channels on the large asperities, and wherein the slurry channels are cut in such a way as to facilitate slurry movement across the large asperities during a CMP polishing process.

Description

PRIORITY DATA

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/333,162, filed on May 10, 2010, which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to CMP pad conditioners used to remove material from (e.g., smooth, polish, dress, etc.) CMP pads. Accordingly, the present invention involves the fields of chemistry, physics, and materials science.

BACKGROUND OF THE INVENTION

The semiconductor industry currently spends in excess of one billion U.S. dollars each year manufacturing silicon wafers that must exhibit very flat and smooth surfaces. Known techniques to manufacture smooth and even-surfaced silicon wafers are plentiful. The most common of these involves the process known as Chemical Mechanical Polishing (CMP) which includes the use of a polishing pad in combination with an abrasive slurry. Of central importance in all CMP processes is the attainment of high performance levels in aspects such as uniformity of polished wafer, smoothness of the IC circuitry, removal rate for productivity, longevity of consumables for CMP economics, etc.

SUMMARY OF THE INVENTION

The present invention provides CMP pad dressers and methods for dressing or conditioning CMP pads. In one aspect, for example, a CMP pad conditioner is provided. Such a conditioner can include a support matrix, and a plurality of smooth superabrasive particles disposed in the support matrix, where the smooth superabrasive particles are operable to cut large asperities in a CMP pad. The conditioner also includes a plurality of rough superabrasive particles disposed in the support matrix, where the rough superabrasive particles operable to cut slurry channels on the large asperities, and wherein the slurry channels are cut in such a way as to facilitate slurry movement across the large asperities during a CMP polishing process.
Various configurations for superabrasive particles are contemplated. In one aspect, for example, cutting tips of the plurality of rough and the plurality of smooth superabrasive particles are substantially leveled to an RA of from about 1 micron to about 10 microns. In another aspect, the plurality of smooth superabrasive particles are divided into one or more discrete smooth superabrasive particle regions, and the plurality of rough superabrasive particles are divided into one or more discrete rough superabrasive particle regions. In a more specific aspect, the discrete smooth superabrasive particle regions and the discrete rough superabrasive particle regions are arranged in an alternating pattern. Alternatively, in one aspect the plurality of smooth superabrasive particles and the plurality of rough superabrasive particles are interspersed across the support matrix.
Any superabrasive material and material configuration capable of conditioning a CMP pad should be considered to be within the present scope. In one aspect, for example, the smooth superabrasive particles are single crystal superabrasive particles. Single crystals can include, for example, diamond, cubic boron nitride, ceramics, and the like. In one aspect, the single crystal superabrasive particles are single crystal diamond. In another aspect, the rough superabrasive particles are polycrystalline superabrasive particles. Polycrystalline materials can include, for example, diamond, cubic boron nitride, ceramics, and the like. In one aspect, the polycrystalline superabrasive particles are polycrystalline diamond. In yet another aspect, the rough superabrasive particles can include single crystal superabrasive particles having broken tips, edges, faces, or a combination thereof.
A variety of support matrix materials are contemplated, and any material capable of securing superabrasive particles in a tool should be considered to be within the present scope. Support matrix materials can include, without limitation, braze alloys, solid metals including electroplated metals, organic materials, ceramics, and the like. In one aspect, the support matrix is an organic matrix. Examples of organic matrix materials can include, without limitation, amino resins, acrylate resins, alkyd resins, polyester resins, polyamide resins, polyimide resins, polyurethane resins, phenolic resins, phenolic/latex resins, epoxy resins, isocyanate resins, isocyanurate resins, polysiloxane resins, reactive vinyl resins, polyethylene resins, polypropylene resins, polystyrene resins, phenoxy resins, perylene resins, polysulfone resins, acrylonitrile-butadiene-styrene resins, acrylic resins, polycarbonate resins, polyimide resins, and the like, including combinations thereof.
In another aspect of the present invention, a method of conditioning a CMP pad is provided. Such a method can include cutting large asperities into a CMP pad surface using smooth superabrasive particles, and cutting slurry channels on the large asperities of the CMP pad surface using rough superabrasive particles, wherein the slurry channels facilitate slurry movement across the large asperities. Various techniques are contemplated for cutting the large asperities and slurry channels in the CMP pad. In one aspect, for example, the large asperities and the slurry channels are cut simultaneously with the same CMP pad dresser. In another aspect, the large asperities and the slurry channels are cut sequentially with different CMP pad dressers.
In another aspect of the present invention, a CMP pad is provided. Such a pad can include a CMP pad material having a plurality of large asperities cut therein, and a plurality of slurry channels cut in the plurality of large asperities, where the slurry channels are cut so as to facilitate slurry movement across the large asperities during a CMP polishing process. In one specific aspect, the CMP pad material is a poreless CMP pad material.
There has thus been outlined, rather broadly, various features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with any accompanying or following claims, or may be learned by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of an exemplary pad conditioner in accordance with an embodiment of the invention.

It will be understood that the above figure is merely for illustrative purposes in furthering an understanding of the invention. Further, the figure may not be drawn to scale, thus dimensions, particle sizes, and other aspects may, and generally are, exaggerated to make illustrations thereof clearer. Therefore, it will be appreciated that departure can and likely will be made from the specific dimensions and aspects shown in the figure in order to produce the pad conditioners of the present invention.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to be understood that this invention is not limited to the particular structures, process steps, or materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.
It should be noted that, as used in this specification and any appended or following claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a particle” can include one or more of such particles.

Definitions

In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set forth below.
As used herein, the terms “pad conditioner” and “pad dresser” can be used interchangeably, and refer to a tool used to condition or dress a pad, such as a CMP pad.
As used herein, a pad conditioner “substrate” or “support substrate” refers to a portion of a pad conditioner that supports an organic matrix, and to which abrasive materials, segment blanks that carry abrasive materials, cutting elements, control elements, etc. may be affixed. Substrates useful in the present invention may be of a variety of shapes, thicknesses, or materials that are capable of supporting an organic matrix in a manner that is sufficient to provide a pad conditioner useful for its intended purpose. Substrates may be of a solid material, a powdered material that becomes solid when processed, or a flexible material. Examples of typical substrate materials include without limitation, metals, metal alloys, ceramics, relatively hard polymers or other organic materials, glasses, and mixtures or combinations thereof.
As used herein, an “abrading surface or point” may be used to refer to a surface, edge, face, point or peak of an abrasive segment or cutting element that contacts and removes material from a CMP pad. Generally speaking, the abrading surface or point is the portion of the abrasive segment that first contacts the CMP pad as the abrasive segment or cutting element and the CMP pad are brought into contact with one another.
As used herein, “segment blank” refers to a structure similar in many respects to the pad conditioner substrates defined above. Segment blanks are utilized in the present invention to carry abrasive layers: attachment of the abrasive layers to the pad conditioner substrates is typically achieved by way of attaching the segment blanks to the pad conditioner substrates. It is important to note that a variety of techniques of attaching the segment blanks to the substrates, and a variety of techniques of attaching the abrasive layers to the segment blanks, are discussed herein. It is to be understood that all of these various attachment mechanisms can be used interchangeably herein: that is, if a method of attaching a segment blank to a substrate is discussed herein, the method of attachment discussed can also be used to attach an abrasive layer to a segment blank. For any particular CMP pad dresser being discussed, however, it is understood that attachment methods of the abrasive layers to the segment blanks can differ from, or can be the same as, the method used to attach the segment blanks to the pad conditioner substrate.
As used herein, “superhard” may be used to refer to any crystalline, or polycrystalline material, or mixture of such materials which has a Mohr's hardness of about 8 or greater. In some aspects, the Mohr's hardness may be about 9.5 or greater. Such materials include but are not limited to diamond, polycrystalline diamond (PCD), cubic boron nitride (cBN), polycrystalline cubic boron nitride (PcBN), corundum and sapphire, as well as other superhard materials known to those skilled in the art. Superhard materials may be incorporated into the present invention in a variety of forms including particles, grits, films, layers, pieces, segments, etc. In some cases, the superhard materials of the present invention are in the form of polycrystalline superhard materials, such as PCD and PcBN materials.
As used herein, “organic material” refers to a semisolid or solid complex or mix of organic compounds. “Organic material layer” and “organic matrix” may be used interchangeably, and refer to a layer or mass of a semisolid or solid complex or mix of organic compounds, including resins, polymers, gums, etc. The organic material can be a polymer or copolymer formed from the polymerization of one or more monomers. In some cases, such organic material can be adhesive.
As used herein, the process of “brazing” is intended to refer to the creation of chemical bonds between the carbon atoms of the superabrasive particles/materials and the braze material. Further, “chemical bond” means a covalent bond, such as a carbide or boride bond, rather than mechanical or weaker inter-atom attractive forces. Thus, when “brazing” is used in connection with superabrasive particles a true chemical bond is being formed. However, when “brazing” is used in connection with metal to metal bonding the term is used in the more traditional sense of a metallurgical bond. Therefore, brazing of a superabrasive segment to a tool body does not necessarily require the presence of a carbide former.
As used herein, an “abrasive layer” describes a variety of structures capable of removing (e.g., cutting, polishing, scraping) material from a CMP pad. An abrasive layer can include a mass having several cutting points, ridges or mesas formed thereon or therein. It is notable that such cutting points, ridges or mesas may be from a multiplicity of protrusions or asperities included in the mass. Furthermore, an abrasive layer can include a plurality of individual abrasive particles that may have only one cutting point, ridge or mesa formed thereon or therein. An abrasive layer can also include composite masses, such as PCD pieces, segment or blanks, either individually comprising the abrasive layer or collectively comprising the abrasive layer.
As used herein, “metallic” includes any type of metal, metal alloy, or mixture thereof, and specifically includes but is not limited to steel, iron, and stainless steel.
As used herein, “material characteristic” refers to the physical and/or chemical properties of a CMP pad. These can include properties such as molecular makeup, compressibility, softness, pore density, and the like.
As used herein, “cutting element” refers to an element of a CMP pad dresser that is intended to cut, abrade, remover, or otherwise reorganize the material of a CMP pad for the purpose of conditioning or dressing. Cutting elements can function using a point, edge, face, or any other region of the cutting element that is capable of conditioning or dressing the CMP pad. Cutting elements should be considered to include individual cutters such as diamond particles, as well as segment blanks that contain multiple cutters provided the context allows.
As used herein, the term “substantially” refers to the complete or nearly complete extent or degree of an action, characteristic, property, state, structure, item, or result. As an arbitrary example, when two or more objects are referred to as being spaced a “substantially” constant distance from one another, it is understood that the two or more objects are spaced a completely unchanging distance from one another, or so nearly an unchanging distance from one another that a typical person would be unable to appreciate the difference. The exact allowable degree of deviation from absolute completeness may in some cases depend upon the specific context. However, generally speaking the nearness of completion will be so as to have the same overall result as if absolute and total completion were obtained.
The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of an action, characteristic, property, state, structure, item, or result. As an arbitrary example, a cavity that is “substantially free of” foreign matter would either completely lack any foreign matter, or so nearly completely lack foreign matter that the effect would be the same as if it completely lacked foreign matter. In other words, a cavity that is “substantially free of” foreign matter may still actually contain minute portions of foreign matter so long as there is no measurable effect upon the cavity as a result thereof.
As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary.
Concentrations, amounts, particle sizes, volumes, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
As an illustration, a numerical range of “about 1 micrometer to about 5 micrometers” should be interpreted to include not only the explicitly recited values of about 1 micrometer to about 5 micrometers, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5, etc. This same principle applies to ranges reciting only one numerical value. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.

The Invention

The present invention generally provides pad conditioners and associated methods that can be utilized in conditioning (e.g., smoothing, polishing, dressing) or otherwise affecting a CMP pad to remove material from the CMP pad in order to provide a finished, smooth and/or flat surface to the pad. Pad conditioners of the present invention can be advantageously utilized, for example, in dressing CMP pads that are used in polishing, finishing or otherwise affecting silicon wafers.
It has now been discovered that CMP processing can be improved by conditioning the CMP pad in such a way as to facilitate slurry movement across pad asperities. This can be accomplished by conditioning the CMP pad with superabrasive particles having smooth surfaces and with superabrasive particles having rough surfaces. Because smooth superabrasive particles generally do not have sharp cutting regions, they tend to cause significant elastic and plastic deformation of the pad prior to pad penetration. As a result, smooth superabrasive particles function to roughen the CMP pad by creating large asperities in the pad surface.
Rough superabrasive particles, on the other hand, have sharp cutting regions (e.g. tips, edges, and/or faces) that can readily cut the CMP pad with less deformation as compared to smooth superabrasive particles. These sharp cutting regions can include, without limitation, broken single crystal particles or polycrystalline particles having a multitude of cutting crystals. These rough superabrasive particles function to remove the glaze from the pad surface during the conditioning process. Additionally, rough superabrasive particles cut small slurry channels into the pad surface along the asperities. During a CMP operation, slurry tends to accumulate in the valleys between asperities rather than at the asperity tips, due in part to the contact pressure exerted between the asperity tips and the workpiece. Much of the CMP polishing occurs at the tips of the asperities, and as such, slurry is often not in optimal contact with the workpiece being polished. This situation can be particularly problematic for polishing procedures utilizing the slurry to cause oxidative reactions on materials such as copper. Because less slurry contacts the workpiece, less oxidative reaction occurs. Slurry channels in the asperities thus facilitate slurry movement out of the valleys between the asperities and across the asperities themselves. As such, a greater proportion of the slurry can be present on the asperities during a CMP operation.
Various techniques can be utilized to condition a CMP pad with both smooth and rough superabrasive particles. For example, in one aspect the CMP pad can be sequentially conditioned using a conditioner having one type of superabrasive particle, and then conditioned using a conditioner having the other type of superabrasive particle. For example, the CMP pad could be conditioned using a conditioner having smooth superabrasive particles, and then conditioned using a conditioner having rough superabrasive particles. In another aspect, a CMP pad conditioner can have both smooth and rough superabrasive particles to condition the CMP pad concomitantly.
The smooth and rough superabrasive particles can be incorporated into a CMP pad conditioner in a variety of ways. A CMP pad conditioner will generally have a support substrate to which the superabrasive particles are coupled using a support matrix. In some cases, the support substrate can be constructed from the support matrix. In some aspects, the superabrasive particles can be disposed directly into the support matrix. In other aspects the superabrasive particles can be coupled to a segment blank that is then disposed into the support matrix. This latter aspect allows smaller segments of superabrasive particles to be constructed and then incorporated into the CMP pad conditioner.
One factor that can impact the methods of constructing a CMP pad conditioner is the relative leveling of the superabrasive particles across the surface of the conditioner. A variety of contours or profiles are possible across the tips of the superabrasive particles in a conditioner. For example, the profile can be a flat profile, where the superabrasive particle tips are leveled along a plane. The tips can be arranged along a slope or a curvature as well. Such an arrangement is still considered to be “leveled” because the tips lie along a predetermined profile. Particle tips that sit significantly lower or higher than this profile would thus not be leveled. Those that sit too low do not contact the pad with sufficient pressure to condition, while those that sit too high cut very large asperities that can cause damage to the workpiece. Additionally, particles that sit too high above the profile experience greater drag from the CMP pad, and can be pulled loose from the conditioner. When this happens, the dislodged particle can cause damage to the workpiece.
In addition to the effectiveness of cutting and the lower risk of workpiece damage, leveled particle tips allows optimal cutting of slurry channels in the asperities of the pad. For example, rough superabrasive particles that sit below the profile may not cut channels to the tips of the asperities, potentially limiting the movement of slurry to the contact point between the workpiece and the asperities. Rough particles that sit above the profile may cut the asperities so aggressively that the benefits provided by the smooth superabrasive particles are limited.
Making a conditioner having leveled tips can be problematic, however, particularly using conventional superabrasive tool techniques. For example, traditional braze alloy support matrix tools embed superabrasive particles in a green braze alloy precursor. The braze alloy is melted and then allowed to cool in order to affix the superabrasive particles. Even assuming the tips of the superabrasive particle were leveled prior to melting the braze alloy, the cooling process causes the support substrate to warp, thus pulling the tips out of the leveled alignment.
Various techniques are contemplated for the leveling of superabrasive tips in a CMP pad conditioner, and any technique that is capable of producing leveled tips in a finished conditioner should be considered to be within the present scope. In one aspect, for example, the support matrix can be an organic material. Organic materials can be cured at temperatures that do not cause warpage of the support substrate, and as such, particle tips that are leveled prior to curing will remain leveled after curing. Organic matrix materials can be problematic, however, because superabrasive particles are much more weakly bonded to an organic matrix as compared to a braze alloy. As a solution to this weak bonding problem, the inventor has discovered that superabrasive particles can be sufficiently retained in an organic matrix by arranging the particles such that mechanical stress or friction is evenly distributed across all superabrasive particles in the matrix.
As such, the smooth and rough superabrasive particles can be directly disposed in an organic matrix, or they can be coupled to a segment blank and the segment blank can be disposed in the organic matrix. Superabrasive particles can be coupled to the segment blank using an organic material, a braze alloy, a ceramic material, electroplating, and the like. Segment blanks can be useful because superabrasive particles can be more easily leveled across a small area as compared to an entire CMP pad conditioner surface. In the case of braze alloys for example, warpage of a segment blank is much less during cooling because the surface area of the segment blank is much smaller that the support substrate. As such, the leveled configuration can be maintained during brazing of the segment blank. The segment blanks can then be coupled to the surface of the support substrate. If a braze alloy is used to secure the segment blank to the support substrate, the warpage of the support substrate is reduced by the added stiffness of the segment blanks. As such, the segment blanks can be secured to the support substrate using an organic material, a braze alloy, a ceramic material, electroplating, and the like.
Other advantages for using segment blanks include the ability to customize methods of attachment of the abrasive layer to the segment blank independently of methods of attachment of the segment blank or blanks to the pad conditioner substrate. For example, as various attachment methods may involve very high temperatures and/or pressures, very demanding environmental conditions, or simply are very labor intensive when attempted with pad conditioners of large or complex surface areas, performing the attachment method on distinct, easily handled segment blanks can improve costs, efficiencies and integrities of the attachment process. Also, leveling of the superabrasive particles on each segment blank can be performed more easily when done in discrete, relatively small lots. The resulting plurality of abrasive segments can likewise be more easily positioned, leveled, spaced, oriented, etc., across the face of the pad conditioner substrate after the abrasive layer is individually attached to each of the abrasive segments.
In addition, by obtaining a plurality of abrasive segments, each with a different configuration of superabrasive particles already attached thereto, an abrasive pattern across the face of the pad conditioner substrate can be designed to optimize various conditioning procedures. For example, the spacing between adjacent abrasive segments can be carefully selected to aid in, or better control, the flow of various fluids (e.g., slurry) around and through the abrasive segments to increase the efficacy and efficiency of the material removing process. Also, as shown in FIG. 1, segment blanks having differing abrasive profiles (e.g., different sizes, shapes, abrasive aggressiveness, etc.) can be used on a single substrate, to enable customization of an abrading profile of the pad conditioner as a whole.
The rough and smooth superabrasive particles can be leveled to various degrees depending on the nature of the CMP pad and the workpiece being processed. While the cutting tips of the superabrasive particles lie along a specific profile that may or may not be planar, leveling refers to the deviation from that profile. In one aspect, for example, the cutting tips of the plurality of rough and the plurality of smooth superabrasive particles are substantially leveled to and RA of from about 1 to about 10 microns. In another aspect, the cutting tips of the plurality of rough and the plurality of smooth superabrasive particles are substantially leveled to and RA of from about 2 to about 3 microns.
Whether the superabrasive particle are disposed directly in the support matrix or are coupled to segment blanks, various arrangements are contemplated. Arrangement schemes can vary depending on the desired conditioning of the pad, and as such, the following arrangements should not be seen as limiting. For example, in one aspect smooth superabrasive particles are divided into one or more discrete smooth superabrasive particle regions, and the rough superabrasive particles are divided into one or more discrete rough superabrasive particle regions. These regions can be regions of particular types of superabrasive particles disposed directly in the support matrix at specific locations, or segment blanks can be constructed having a single type of superabrasive particle embedded thereon. In one specific aspect, as is shown in FIG. 1, the discrete smooth superabrasive particle regions 12 and the discrete rough superabrasive particle regions 14 are arranged on the support substrate 16 in an alternating pattern. In another aspect, the plurality of smooth superabrasive particles and the plurality of rough superabrasive particles are interspersed across the support matrix (not shown). This can be accomplished through both types of superabrasive particles interspersed directly into the support matrix, or by interspersing a mixture of both types of superabrasive particles on a segment blank.
The CMP pad conditioner can also include multiple annular rings of superabrasive particle regions, as opposed to the single annular ring shown in FIG. 1. Furthermore, it should be noted that regions or segments would also include arrangements where grouped multiples of one or more regions or segments were included in the pattern.
While these techniques can be used to dress a variety of CMP pad materials, they can be particularly beneficial for dressing poreless CMP pad materials. Poreless CMP pads do not hold and move slurry effectively because they lack pores to contain and hold the slurry. As such, the problems associated with the slurry being contained in the valleys between asperities is exacerbated by such materials.
By cutting slurry channels through the pad surface, slurry movement to the work piece up the asperities is facilitated, thus increasing the effectiveness of poreless materials. Thus smooth superabrasive particles can roughen such a pad, and rough superabrasive particles can cut slurry channels that allow slurry to wick across the pad surface.
The methods according to aspects of the present invention can also be used to dress impregnated pads, such as graphite-impregnated pads. Additional information regarding such pads can be found in U.S. Pat. No. 7,494,404, filed on Jul. 6, 2007, and in U.S. patent application Ser. No. 12/389,922, filed on Feb. 20, 2009, both of which are incorporated herein by reference.
A variety of materials are contemplated for use as rough and smooth superabrasive particles. Any superabrasive known that can be utilized in a CMP pad dresser should be considered to be within the present scope. Non-limiting examples of such materials include diamond materials, nitride materials, ceramics, and the like. In one aspect, the superabrasive particles include diamond materials. Such diamond materials can include natural or synthetic diamond, single crystal, polycrystalline, and the like. In another aspect, the superabrasive particles include cubic boron nitride materials.
In one aspect, the smooth superabrasive particles are single crystal superabrasive particles. In one specific aspect, the single crystal superabrasive particles can be diamond. Euhedral diamond crystals have obtuse tips due to the crystallographic angles formed by the (100), (111), (110) and other faces. Such diamond materials can be used as smooth superabrasive particles to form large asperities in the CMP pad. Smooth superabrasive particles can also be referred to as deforming superabrasive particles.
In another aspect, rough superabrasive particles can be single crystal superabrasive particles having broken tips, edges, faces, or a combination thereof. The broken portions tend to be sharp, allowing the cutting of the slurry channels into the pad material. In yet another aspect, the rough superabrasive particles are polycrystalline superabrasive particles. Polycrystalline materials have a multitude of smaller crystals at the particle surface that can effectively cut slurry channels into the pad, as well as facilitating the removal of glaze and other debris. In one specific aspect, the polycrystalline superabrasive particles are polycrystalline diamond. Rough superabrasive particles can also be referred to as cutting superabrasive particles.
In one aspect, the smooth superabrasive particles can be distinguished by how far into the CMP pad a particle can be pressed before cutting occurs. In one aspect, for example, a smooth superabrasive particle is pressed into a CMP pad at least 15 microns before cutting occurs. In another aspect, a smooth superabrasive particle is pressed into a CMP pad at least 20 microns before cutting occurs. Similarly, rough superabrasive particles can be distinguished by how far into the CMP pad a particle can be pressed before cutting occurs. In one aspect, for example, a rough superabrasive particle begins cutting when pressed into a CMP pad less than or equal to about 10 microns. In another aspect, a rough superabrasive particle begins cutting when pressed into a CMP pad less than or equal to about 5 microns.
The pad conditioner substrate can vary according to the applications for which the pad conditioner is designed, but in one aspect includes a face on which the support matrix can be affixed to allow the pad conditioner to be used to grind, plane, cut or otherwise remove material from a CMP pad. In one aspect, the conditioner or support substrate can be stainless steel. In another aspect, the support substrate can be regular steel. If regular steel is used, it may be beneficial to electroplate the working surface following fixing the superabrasive particles to provide acid resistance to the conditioner.
Additional and varying abrasive segments for use in the present invention are also contemplated. For example, use is contemplated of the various cutting elements/abrasive segments detailed in U.S. patent application Ser. No. 11/357,713, filed Feb. 17, 2006, which is hereby incorporated herein by reference. In addition, the abrasive segments can be formed utilizing ceramic components (as either or both the segment blank and/or the abrasive layer), electroplating techniques, etc.
The various segment blanks shown and discussed herein can be formed from a variety of materials, including, without limitation, metallic materials such as aluminum, copper, steel, metal alloys, etc., ceramic materials, glasses, polymers, composite materials, etc. Generally speaking, virtually any material to which a superabrasive particle can be attached thereto will suffice.
Various organic materials are contemplated for use as a support matrix and/or to be used to secure superabrasive particles to a segment blank. Examples of suitable organic matrix materials include, without limitation, amino resins, acrylate resins, alkyd resins, polyester resins, polyamide resins, polyimide resins, polyurethane resins, phenolic resins, phenolic/latex resins, epoxy resins, isocyanate resins, isocyanurate resins, polysiloxane resins, reactive vinyl resins, polyethylene resins, polypropylene resins, polystyrene resins, phenoxy resins, perylene resins, polysulfone resins, acrylonitrile-butadiene-styrene resins, acrylic resins, polycarbonate resins, polyimide resins, and mixtures thereof. In one specific aspect, the organic matrix material can be an epoxy resin. In another aspect, the organic matrix material can be a polyimide resin. In yet another aspect, the organic matrix material can be a polyurethane resin.
So-called “reverse casting” methods can be used to accurately and controllably orient and attach superabrasive particles onto a segment blank, as well as to orient and attach the segment blanks to the pad conditioner support substrate. Such methods can include initially securing a superabrasive material, e.g., a plurality of superabrasive particles or a segment blank, to a substrate using a “mask” material. The portions of the particles protruding from the mask material can then be attached to a substrate, such as a segment blank, using the methods discussed herein, after which (or during which), the masking material can be removed.
Suitable reverse casting methods can be found in various patents and patent applications to the present inventor, including U.S. Patent Application Ser. No. 60/992,966, filed Dec. 6, 2007; U.S. patent application Ser. No. 11/804,221, filed May 16, 2007; and U.S. patent application Ser. No. 11/805,549, filed May 22, 2007, each of which is hereby incorporated herein by reference. These techniques can also be used when attaching the abrasive segments of the present invention to pad conditioner support substrate in addition to attaching the superabrasive particles to the segment blanks. Such techniques allow very precise control of lateral placement of the abrasive segments or superabrasive particles, as well as very precise control of relative elevation of the abrasive segments or superabrasive particles.
When an organic bonding material layer is utilized, methods of curing the organic material layer can be a variety of processes known to one skilled in the art that cause a phase transition in the organic material from at least a pliable state to at least a rigid state. Curing can occur, without limitation, by exposing the organic material to energy in the form of heat, electromagnetic radiation, such as ultraviolet, infrared, and microwave radiation, particle bombardment, such as an electron beam, organic catalysts, inorganic catalysts, or any other curing method known to one skilled in the art.
In one aspect of the present invention, the organic material layer may be a thermoplastic material. Thermoplastic materials can be reversibly hardened and softened by cooling and heating respectively. In another aspect, the organic material layer may be a thermosetting material. Thermosetting materials cannot be reversibly hardened and softened as with the thermoplastic materials. In other words, once curing has occurred, the process can be essentially irreversible, if desired.
As a more detailed list of what is described above, organic materials that may be useful in embodiments of the present invention include, but are not limited to: amino resins including alkylated urea-formaldehyde resins, melamine-formaldehyde resins, and alkylated benzoguanamine-formaldehyde resins; acrylate resins including vinyl acrylates, acrylated epoxies, acrylated urethanes, acrylated polyesters, acrylated acrylics, acrylated polyethers, vinyl ethers, acrylated oils, acrylated silicons, and associated methacrylates; alkyd resins such as urethane alkyd resins; polyester resins; polyamide resins; polyimide resins; reactive urethane resins; polyurethane resins; phenolic resins such as resole and novolac resins; phenolic/latex resins; epoxy resins such as bisphenol epoxy resins; isocyanate resins; isocyanurate resins; polysiloxane resins including alkylalkoxysilane resins; reactive vinyl resins; resins marketed under the Bakelite™ trade name, including polyethylene resins, polypropylene resins, epoxy resins, phenolic resins, polystyrene resins, phenoxy resins, perylene resins, polysulfone resins, ethylene copolymer resins, acrylonitrile-butadiene-styrene (ABS) resins, acrylic resins, and vinyl resins; acrylic resins; polycarbonate resins; and mixtures and combinations thereof. In one aspect of the present invention, the organic material may be an epoxy resin. In another aspect, the organic material may be a polyimide resin. In yet another aspect, the organic material may be a polyurethane resin.
Numerous additives may be included in the organic material to facilitate its use. For example, additional crosslinking agents and fillers may be used to improve the cured characteristics of the organic material layer. Additionally, solvents may be utilized to alter the characteristics of the organic material in the uncured state. Also, a reinforcing material may be disposed within at least a portion of the solidified organic material layer. Such reinforcing material may function to increase the strength of the organic material layer, and thus further improve the retention of the individual abrasive segments. In one aspect, the reinforcing material may include ceramics, metals, or combinations thereof. Examples of ceramics include alumina, aluminum carbide, silica, silicon carbide, zirconia, zirconium carbide, and mixtures thereof.
Additionally, in one aspect a coupling agent or an organometallic compound may be coated onto the surface of each superabrasive material to facilitate the retention of the superabrasive particles in the organic material via chemical bonding. A wide variety of organic and organometallic compounds is known to those of ordinary skill in the art and may be used. Organometallic coupling agents can form chemicals bonds between the superabrasive materials and the organic material matrix, thus increasing the retention of the superabrasive materials therein. In this way, the organometallic coupling agent can serve as a bridge to form bonds between the organic material matrix and the surface of the superabrasive material. In one aspect of the present invention, the organometallic coupling agent can be a titanate, zirconate, silane, or mixture thereof. The amount of organometallic coupling agent used can depend upon the coupling agent and on the surface area of the superabrasive material. Oftentimes, 0.05% to 10% by weight of the organic material layer can be sufficient.
Specific non-limiting examples of silanes suitable for use in the present invention include: 3-glycidoxypropyltrimethoxy silane (available from Dow Corning as Z-6040); γ-methacryloxy propyltrimethoxy silane (available from Union Carbide Chemicals Company as A-174); β-(3,4-epoxycyclohexyl)ethyltrimethoxy silane, γ-aminopropyltriethoxy silane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxy silane (available from Union Carbide, Shin-etsu Kagaku Kogyo K.K., etc.). Specific non-limiting examples of titanate coupling agents include: isopropyltriisostearoyl titanate, di(cumylphenylate)oxyacetate titanate, 4-aminobenzenesulfonyldodecylbenzenesulfonyl titanate, tetraoctylbis (ditridecylphosphite) titanate, isopropyltri(N-ethylamino-ethylamino) titanate (available from Kenrich Petrochemicals. Inc.), neoalkyoxy titanates such as LICA-01, LICA-09, LICA-28, LICA-44 and LICA-97 (also available from Kenrich), and the like. Specific non-limiting examples of aluminum coupling agents include acetoalkoxy aluminum diisopropylate (available from Ajinomoto K.K.), and the like. Specific non-limiting examples of zirconate coupling agents include: neoalkoxy zirconates, LZ-01, LZ-09, LZ-12, LZ-38, LZ-44, LZ-97 (all available from Kenrich Petrochemicals, Inc.), and the like. Other known organometallic coupling agents, e.g., thiolate based compounds, can be used in the present invention and are considered within the scope of the present invention.
Metal brazing can also be utilized to attach superabrasive particles to a segment blank or to attach a segment blank to a support substrate. Metal brazing techniques are known in the art. For example, in fabricating a diamond particle abrasive segment, the process can include mixing diamond particles (e.g., 40/50 U.S. mesh grit) with a suitable metal support matrix (bond) powder (e.g., cobalt powder of 1.5 micrometer in size). The mixture is then compressed in a mold to form a desired shape. This “green” form of the tool can then be consolidated by sintering at a temperature between 700-1200 degrees C. to form a single body with a plurality of abrasive particles disposed therein. Finally, the consolidated body can be attached (e.g., by brazing) to a segment blank. Many other exemplary uses of this technology are known to those having ordinary skill in the art. It should also be noted that various sintering methods can also be utilized to attach the abrasive layer to the segment blank. Suitable sintering methods will be easily appreciated by one of ordinary skill in the art having possession of this disclosure.
The abrasive layer can also be attached to a segment blank by way of known electroplating and/or electrodeposition processes. As an example of a suitable method for positioning and retaining abrasive materials prior to and during the electrodeposition process, a mold can be used that includes an insulating material that can effectively prevent the accumulation of electrodeposited material on the molding surface. Abrasive particles can be held on the molding surface of the mold during electrodeposition. As such, the accumulation of electrodeposited material can be prevented from occurring on the particle tips and the working surface of the pad conditioner substrate. Such techniques are described in U.S. patent application Ser. No. 11/292,938, filed Dec. 2, 2005, which is hereby incorporated herein by reference.
One or more apertures can extend through the insulating material to allow for circulation of an electrolytic fluid from an area outside the mold through the mold and to the surface of the pad conditioner substrate in order to facilitate electrodeposition. Such circulation can be advantageous as it is generally necessary to keep a sufficient concentration of ions in an electrolytic fluid at the location of electrodeposition. Other well known techniques can also be utilized, it being understood that the above-provided example is only one of many suitable techniques.

EXAMPLES

The following examples present various methods for making the pad conditioners of the present invention. Such examples are illustrative only, and no limitation on the present invention is to be thereby realized.

Example 1

A segment blank is formed by arranging smooth diamond particles (e.g. 50/60 mesh) on a stainless steel flat mold (also, a slightly convex or contoured mold can be utilized) having a layer of adhesive (e.g. acrylic). A hard rubber material is used to press individual diamond particles into the adhesive while tips of the particle are leveled by the flat mold. A mixture of epoxy and hardener is then poured onto the particles protruding outside the adhesive (a containment ring oriented outside the mold can retain the epoxy). After curing, the mold is then removed and the adhesive is peeled away. The resulting segment blank contains smooth diamond particles protruding outside a solidified epoxy substrate.

Example 2

A segment blank is formed by arranging 80/90 mesh broken single crystal diamond particles and brazing the diamond particles to a stainless steel substrate. The resulting segment blank contains rough diamond particle protruding from a solidified braze alloy.

Example 3

A composite design combining the embodiments of Example 1 and Example 2 discussed above. Segment blanks from Examples 1 and 2 are arranged on a temporary substrate and a flat plate is used to level the superabrasive particle tips of the segment blanks. While these tips are leveled, the bases of the segment blanks are secured with an epoxy resin.

Example 4

Two types of segment blanks are formed by brazing diamond particles with Nichrobraz LM on segment blank substrates. The segment blank substrates are stainless steel (316), 20 mm in diameter by 4 mm in thickness. Smooth-type segment blanks are made with 60/70 mesh MBG-660 (Diamond Innovations product designation) having blocky or smooth diamond particle shapes, and rough-type segment blanks are made with 100/110 mesh MBG-620 having irregular shaped diamond particles. The two types of segment blanks are placed on a flat stainless steel substrate in an alternating pattern with a molded ceramic spacer. A flat stainless steel plate is pressed on the diamond tips to level the segment blanks to within 20 microns. Epoxy is added to surround each segment blank, and is UV cured to harden the matrix.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention and any appended or following claims are intended to cover such modifications and arrangements. Thus, while the present invention has been described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred embodiments of the invention, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made without departing from the principles and concepts set forth herein.

Claims

1. A CMP pad conditioner, comprising:

a support matrix;

a plurality of smooth superabrasive particles disposed in the support matrix, the smooth superabrasive particles operable to cut large asperities in a CMP pad; and

a plurality of rough superabrasive particles disposed in the support matrix, the rough superabrasive particles operable to cut slurry channels on the large asperities, wherein the slurry channels are operable to facilitate slurry movement across the large asperities during a CMP polishing process.

2. The CMP pad conditioner of claim 1, wherein cutting tips of the plurality of rough and the plurality of smooth superabrasive particles are substantially leveled to an RA of from about 1 to about 10 microns.

3. The CMP pad conditioner of claim 1, wherein the plurality of smooth superabrasive particles are divided into one or more discrete smooth superabrasive particle regions, and wherein the plurality of rough superabrasive particles are divided into one or more discrete rough superabrasive particle regions.

4. The CMP pad conditioner of claim 4, wherein the discrete smooth superabrasive particle regions and the discrete rough superabrasive particle regions are arranged in an alternating pattern.

5. The CMP pad conditioner of claim 1, wherein the plurality of smooth superabrasive particles and the plurality of rough superabrasive particles are interspersed across the support matrix.

6. The CMP pad conditioner of claim 1, wherein the smooth superabrasive particles are single crystal superabrasive particles.

7. The CMP pad conditioner of claim 6, wherein the single crystal superabrasive particles are single crystal diamond.

8. The CMP pad conditioner of claim 1, wherein the rough superabrasive particles are polycrystalline superabrasive particles.

9. The CMP pad conditioner of claim 8, wherein the polycrystalline superabrasive particles are polycrystalline diamond.

10. The CMP pad conditioner of claim 1, wherein the rough superabrasive particles are single crystal superabrasive particles having broken tips, edges, faces, or a combination thereof.

11. The CMP pad conditioner of claim 1, wherein the smooth superabrasive particles have a configuration sufficient to press at least about 15 microns into a CMP pad before cutting occurs.

12. The CMP pad conditioner of claim 1, wherein the rough superabrasive particles have a configuration sufficient to begin cutting when pressed into a CMP pad less than or equal to about 10 microns.

13. The CMP pad conditioner of claim 1, wherein the support matrix is a braze metal matrix.

14. The CMP pad conditioner of claim 1, wherein the support matrix is an organic matrix.

15. The CMP pad conditioner of claim 14, wherein the organic matrix includes a member selected from the group consisting of: amino resins, acrylate resins, alkyd resins, polyester resins, polyamide resins, polyimide resins, polyurethane resins, phenolic resins, phenolic/latex resins, epoxy resins, isocyanate resins, isocyanurate resins, polysiloxane resins, reactive vinyl resins, polyethylene resins, polypropylene resins, polystyrene resins, phenoxy resins, perylene resins, polysulfone resins, acrylonitrile-butadiene-styrene resins, acrylic resins, polycarbonate resins, polyimide resins, and combinations thereof.

16. A method of conditioning a CMP pad, comprising:

cutting large asperities into a CMP pad surface using smooth superabrasive particles; and

cutting slurry channels on the large asperities of the CMP pad surface using rough superabrasive particles, wherein the slurry channels facilitate slurry movement across the large asperities.

17. The method of claim 16, wherein the large asperities and the slurry channels are cut simultaneously with the same CMP pad dresser.

18. The method of claim 16, wherein the large asperities and the slurry channels are cut sequentially with different CMP pad dressers.

19. A CMP pad, comprising:

a CMP pad material having a plurality of large asperities cut therein; and

a plurality of slurry channels cut in the plurality of large asperities, the slurry channels being operable to facilitate slurry movement across the large asperities during a CMP polishing process.

20. The CMP pad of claim 19, wherein the CMP pad material is a poreless CMP pad material.