US20100203806A1

US20100203806A1 - Semiconductor manufacturing apparatus

Info

Publication number: US20100203806A1
Application number: US12/703,027
Authority: US
Inventors: Tomonori Kitakura; Dai Fukushima; Keiji Fujita
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2009-02-09
Filing date: 2010-02-09
Publication date: 2010-08-12
Also published as: JP2010183037A

Abstract

A semiconductor manufacturing apparatus comprising a platen holding a polishing pad; a polishing head including a pressurizing mechanism which presses a surface of a processing target substrate onto the polishing pad; and a plurality of temperature adjusters being provided in the platen in a radial direction of the platen and being capable of adjusting temperatures thereof independently from one another, wherein, when the surface of the processing target substrate is polished by rotating the platen and the polishing head, the temperatures of the temperature adjusters are changed, so that temperature adjustment can be performed selectively on a region ranging on the surface of the processing target substrate in a radial direction thereof.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-27809, filed on Feb. 9, 2009, the entire contents of which are incorporated herein by reference.

BACKGROUND

A chemical mechanical polishing process (hereinafter referred to as a CMP process) is carried out as one of processes for manufacturing semiconductor devices in order to evenly planarize the surface of a polishing target substrate.
This CMP process is generally carried out by supplying a polishing liquid to a polishing pad while rotating a platen that holds the polishing pad and by pressing a semiconductor substrate onto the polishing pad while rotating a polishing head that holds the semiconductor substrate. To be more precise, the semiconductor substrate is polished by an effect of physical friction with the polishing pad and by an effect of a chemical action with the polishing liquid.
However, it has been known that the CMP process causes variation in the polishing amount on the surface of the polishing target substrate. To solve this problem, the pressure from an airbag provided to the polishing head is changed for each predetermined region (hereinafter referred to as a zone) on the surface of the polishing target substrate, whereby the variation in the polishing amount on the surface of the polishing target substrate is reduced.
It is possible to reduce the variation to some extent by performing the variation control using the airbag. However, it is difficult to control the polishing rate on the surface of the polishing target substrate always at a constant level due to controlling of the polishing amount on a region between the zones, reduction in the retentivity of the polishing liquid attributable to abrasion and deterioration of the polishing pad with time along the progress of the polishing process, and change in the temperature of the surface of the polishing target substrate attributable to the reduction.
Accordingly, in order to stabilize the polishing rate on the surface of the polishing target substrate, there has have been studied not only an approach from material perspectives concerning an polishing agent, a polishing pad, a diamond dresser, and the like, but also an approach from the viewpoints of the configuration of and the process control for a CMP apparatus.

SUMMARY

Aspects of the invention relate to a SEMICONDUCTOR MANUFACTURING APPARATUS, and particularly to a chemical mechanical polishing apparatus.
In one aspect of the invention, A semiconductor manufacturing apparatus comprising: a platen holding a polishing pad; a polishing head including a pressurizing mechanism which presses a surface of a processing target substrate onto the polishing pad; and a plurality of temperature adjusters being provided in the platen in a radial direction of the platen and being capable of adjusting temperatures thereof independently from one another, wherein, when the surface of the processing target substrate is polished by rotating the platen and the polishing head, the temperatures of the temperature adjusters are changed, so that temperature adjustment can be performed selectively on a region ranging on the surface of the processing target substrate in a radial direction thereof.

BRIEF DESCRIPTIONS OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

FIG. 1 is a schematic view showing a CMP apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a platen 3 of the CMP apparatus according to the first embodiment of the present invention.

FIG. 3 is a graph showing the relation between the temperature on the surface of a processing target substrate and the polishing rate.

FIG. 4 shows the polishing rate on the surface of the processing target substrate when the platen 3 is rotated at 50 rpm and a polishing head 6 is rotated at 55 rpm.

FIG. 5 is a diagram indicating how the surface of the processing target substrate is divided according to the first embodiment of the present invention.

FIGS. 6A to 6E show trajectories which are made on regions on the processing target substrate by bringing polishing pads above temperature adjusters into contact with the surface of the processing target substrate, respectively.

FIG. 7 is another perspective view schematically showing the platen 3 of the CMP apparatus according to the first embodiment of the present invention.

FIG. 8 is a perspective view schematically showing a CMP apparatus according to a second embodiment of the present invention.

FIG. 9 is a perspective view schematically showing a platen 12 of the CMP apparatus according to the second embodiment of the present invention.

FIG. 10 is a block diagram showing an example of a temperature controller 11 of the CMP apparatus according to the second embodiment of the present invention.

DETAILED DESCRIPTION

Various connections between elements are hereinafter described. It is noted that these connections are illustrated in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect.
Embodiments of the present invention will be explained with reference to the drawings as next described, wherein like reference numerals designate identical or corresponding parts throughout the several views.
First Embodiment
FIG. 1 is a perspective view schematically showing a
CMP apparatus according to a first embodiment of the present invention. A CMP apparatus 1 shown in FIG. 1 includes a polishing pad 4 which polishes a substrate by a physical frictional force, and which is attached onto a platen 3 rotatable around a rotary shaft 2.
The CMP apparatus 1 includes a polishing head 6 which is capable of holding a processing target substrate 5 at a position opposed to the polishing pad 4 and pressing the processing surface of the processing target substrate 5 onto the polishing pad 4. The polishing head is movable in a vertical direction and in a horizontal direction.
A polishing liquid supply tube 8 which allows polishing liquid 7 (slurry) to be supplied onto the polishing pad is provided on the polishing pad. The processing target substrate 5 is polished and planarized by a chemical reaction with this polishing liquid 7 and by the physical frictional force with the polishing pad 4.
FIG. 2 is a perspective view schematically showing the platen 3 of the CMP apparatus according to the first embodiment of the present invention. As shown in FIG. 2, this embodiment is characterized in that multiple temperature adjusters 9 each with a Peltier device mounted therein are provided in the surface of the platen 3.
The multiple temperature adjusters 9 are disposed in a radial direction of the platen 3 from the center to the circumference thereof. Although this embodiment will be described for a case of providing five temperature adjusters 9 for convenience, the number of the temperature adjusters 9 is not limited to such number and can be changed as appropriate depending on specifications. In this embodiment, the temperature sensors 9 will be denoted by 9A, 9B, 9C, 9D, and 9E, respectively, starting from a central portion of the platen 3.
The surface of the polishing pad 4 is subjected to temperature control by transmitting a temperature from the rear surface of the polishing pad 4 in accordance with temperature control using the temperature adjusters 9 that are buried in the platen 3.
Each temperature adjuster 9 with the Peltier device mounted therein is preferably formed into a small shape, because it is possible to control temperature control regions on the surface of the processing target substrate 5 more accurately. Moreover, the polishing pad 4 on the platen 3 is preferably made of a high heat transfer material.
Next, a concrete operation of the CMP apparatus according to the first embodiment of the present invention will be described. First, the platen 3 is rotated and the polishing liquid 7 is supplied from the polishing agent supply tube 8 onto the polishing pad 4.
By lifting down the polishing head 6 while supplying the polishing liquid 7, the surface of the processing target substrate is pressed onto the polishing pad 4 and polished. As a method of pressing the surface of the processing target substrate onto the polishing pad 4, it is possible to employ a pressurizing method using a cylinder, an air pressurizing method or the like as appropriate.
FIG. 3 is a graph showing the relation between the temperature of the surface of the processing target substrate and the polishing rate. As shown in FIG. 3, it is apparent that the polishing rate varies depending on the temperature of the surface of the processing target substrate.
In particular, the polishing rate is high in a region where the temperature of the surface of the processing target substrate is in a range from 35° C. to 50° C., which helps to achieve high throughput. Thus, it is preferable to control the temperature within this range.
FIG. 4 shows the polishing rate on the surface of the processing target substrate when the platen 3 is rotated at 50 rpm and the polishing head 6 is rotated at 55 rpm. The horizontal axis in FIG. 4 indicates the coordinate on the surface of the processing target substrate, and the center on the horizontal axis corresponds to the center of the surface of the processing target substrate.
For example, as shown in FIG. 4, the polishing rate is high in a central region near the center of the processing target substrate. On the other hand, the polishing rate is low in circumferential regions near the circumference of the processing target substrate.
To cancel the above-described difference in the polishing rate among the regions, it is conceivable to lower the temperature in the central region on the surface of the processing target substrate where the polishing rate is high while raising the temperature in the circumferential regions on the surface of the processing target substrate where the polishing rate is low. In this way, polishing variation among the zones on the processing target substrate 5 can be suppressed.
In this embodiment, regions being disposed in the radial direction from the center of the processing target substrate 5 and having the common center will be referred to as zones. In this embodiment, the zones will be denoted by a zone a, a zone b, a zone c, a zone d, and a zone e, respectively, starting from the central portion of processing target substrate 5.
This embodiment achieves suppression of polishing variation among the zones on the surface of the processing target substrate by adjusting the temperatures of the respective temperature adjusters 9 with the Peltier devices mounted therein. FIG. 6A shows a trajectory which is made on a region on the processing target substrate by bringing the polishing pad above the temperature adjuster 9A into contact with the surface of the processing target substrate.
Similarly, FIG. 6B, FIG. 6C, FIG. 6D, and FIG. 6E show trajectories which are made on regions on the processing target substrate by bringing the polishing pad above the temperature adjusters 9B, 9C, 9D, and 9E into contact with the surface of the processing target substrate, respectively.
Accordingly, in each of FIGS. 6A to 6E, a region where the trajectory is denser is influenced more strongly by the corresponding temperature adjuster 9 and it is therefore possible to control the temperature in such region selectively.
In the case shown in FIG. 3, it is possible to polish the surface of the processing target substrate without causing variation by lowering the temperature of the temperature adjuster 9C corresponding to the zone a and raising the temperatures of the temperature adjusters 9A and 9E corresponding to the zone e.
Here, the trajectories which are made on the respective regions on the processing target substrate by bringing the polishing pads above the respective temperature adjusters 9 into contact with the surface of the processing target substrate vary depending on the position to press the processing target substrate 5 onto the whole polishing pad 4, i.e., depending on the position of the polishing head 6.
Accordingly, the trajectories are not limited only to those illustrated in FIGS. 6A to 6E. The trajectories can be adjusted as appropriate by changing the position of the polishing head 6.
As shown in FIG. 7, the temperature adjusters 9 may also be provided at positions on the symmetrically-opposite side to the center of the platen 3.
Each of the pairs of temperature adjusters located at mutually symmetrical positions with respect to the center of the platen 3 trace the same trajectory. Hence it is possible to perform the temperature adjustment efficiently as compared to the case of proving the temperature adjusters only on one side.
Moreover, the temperature adjusters 9 of this embodiment are also characterized by having cooling means for lowering the temperature as well as the means for raising the temperature.
Accordingly, in addition to the above-described function to slow down the polishing rate in the region having the high polishing rate, the temperature adjusters 9 also have an effect to suppress influences of friction heat generated by friction between the polishing pad 4 and the processing target substrate 5 in the process of polishing the processing target substrate 5 and thereby to suppress polishing variation.
The temperature of the surface of the processing target substrate may also be lowered by controlling the flow rate of the polishing liquid 7 so as to supplement the temperature adjustment by the temperature adjusters 9. In this case, the temperature of the surface of the processing target substrate can be lowered by increasing the flow rate of the polishing liquid 7. Use of the polishing liquid 7 allows collective temperature control of the entire surface of the processing target substrate.
In this embodiment, the temperature control is performed by using the temperature adjusters to suppress polishing variation among the zones. In addition to this, pressure adjustment using an airbag provided to the polishing head 6 may be used to adjust the polishing rate for each zone more accurately.
In this embodiment, the multiple temperature adjusters 9 with the Peltier devices mounted therein are provided in the surface of the platen 3. By controlling such temperature adjusters independently of one another, it is possible to adjust the polishing rates for any zones on the surface of the processing target substrate.
Second Embodiment
Another embodiment of the present invention will be described below with reference to the drawings. This embodiment is different from the above-described first embodiment in that the platen includes temperature measurement units in addition to the configuration of the first embodiment.
Moreover, this embodiment includes a temperature controller that controls the temperature adjusters on the basis of information from the temperature measurement units. Other features of this embodiment are similar to those in the above-described first embodiment, and the duplicate constituents will be designated by the same reference numerals and description thereof will be omitted.
FIG. 8 is a perspective view schematically showing a CMP apparatus according to a second embodiment of the present invention. A CMP apparatus 10 shown in FIGS. 8 is characterized by including a temperature controller 11 in addition to the configuration of the CMP apparatus 1 of the first embodiment.
FIG. 9 is a perspective view schematically showing a platen 12 of the CMP apparatus according to the second embodiment of the present invention.
As shown in FIG. 9, this embodiment is characterized in that the multiple temperature adjusters 9 with the Peltier devices mounted therein and multiple temperature measurement units 13 are provided in the surface of the platen 12. As similar to the first embodiment, the multiple temperature adjusters 9 are disposed in the radial direction of the platen 12 from the center to the circumference thereof.
The temperature measurement units 13 are provided as many as the temperature adjusters 9 and correspond to the temperature adjusters 9, respectively. Each temperature measurement unit 13 is formed of an infrared temperature measuring device, for example, which is capable of measuring the temperature of the polishing pad 4 above the temperature measurement 13 and the temperature of the surface of the processing target substrate being in contact with the polishing pad 4.
FIG. 9 shows an example of providing the temperature measurement units 13 at positions on the symmetrically-opposite side to the center of the platen 12. However, it is not always necessary to provide the temperature measurement units 13 at positions on the symmetrically-opposite side to the center of the platen 12.
The temperature measurement units 13 only need to be provided on the same circles about the center of the platen 12 as those on which the respectively corresponding temperature adjusters 9 are located. In FIG. 9, the temperature measurement units 13A, 13B, 13C, 13D, and 13E correspond to the temperature adjusters 9A, 9B, 9C, 9D, and 9E, respectively.
Being provided on the same circles about the center of the platen 12 as those on which the respectively corresponding temperature adjusters 9 are located, the temperature measurement units 13 trace the same trajectories on the surface of the processing target substrate as the trajectories of the corresponding temperature adjusters 9 thereon.
Accordingly, the influence of the temperature adjusters corresponding to the temperature measurement units on the surface of the processing target substrate can be measured in real time. Each of the temperature measurement units 13 automatically measures the temperature of the surface of the processing target substrate and transmits measurement data to the temperature controller 11.
FIG. 10 is a block diagram showing an example of the temperature controller 11. The temperature controller 11 according to this embodiment includes: a memory unit 14 that temporarily stores the temperature data measured by the temperature measurement units 13; a controller 15 that determines the intensities of signals to the respective temperature adjusters 9 on the basis of the temperature data; and a voltage converter 16 that adjusts supply voltages to the respective temperature adjusters 9 on the basis of the respective signal intensities from the controller 15.
Next, a concrete operation of the CMP apparatus according to the second embodiment of the present invention will be described. First, the platen 12 is rotated and the polishing liquid 7 is supplied from the polishing agent supply tube 8 onto the polishing pad 4.
By lifting down the polishing head 6 while supplying the polishing liquid 7, the surface of the processing target substrate is pressed onto the polishing pad 4 and polished. As a method of pressing the surface of the processing target substrate onto the polishing pad 4, it is possible to employ a pressurizing method using a cylinder, an air pressurizing method or the like as appropriate.
At this time, the polishing process is performed while adjusting the temperature of each of the temperature adjusters 9 on the basis of a preset initial condition. The temperature of the surface of the processing target substrate is measured by each of the temperature measurement units 13 while adjusting the temperature of each of the temperature adjusters 9.
The temperature measurement units 13 are provided on the same circles about the center of the platen 12 as those on which the respectively corresponding temperature adjusters 9 are located, whereby it is possible to accurately grasp the temperature information on the respective zones subjected to the temperature control. This is desirable because the temperature control can be performed more precisely.
The temperature data measured by the temperature measurement units 13 is transmitted to the temperature controller 11 in real time. The temperature controller 11 adjusts the intensities of signals to the respective temperature adjusters on the basis of the temperature data obtained from the temperature measurement units 13 in such a way as to make uniform the temperature of the surface of the processing target substrate, and then transmits the signals to the respective temperature adjusters. In this way, the temperature of the surface of the processing target substrate is made more uniform. Hence it is possible to maintain a uniform polishing rate on the surface of the processing target substrate.
It is to be noted that the present invention is not limited to the above-described embodiments and can be implemented in various modified forms without departing from the scope of the present invention.

Claims

1. A semiconductor manufacturing apparatus comprising:

a platen and a polishing pad on the platen;

a polishing head comprising a presser configured to press a surface of a processing target substrate onto the polishing pad; and

a plurality of temperature adjusters in the platen in a radial direction of the platen configured to adjust temperatures of the platen independently from one another,

wherein the temperatures of the temperature adjusters are adjusted while the surface of the processing target substrate is being polished by rotating the platen and the polishing head, in such a manner that the temperature adjusters are configured to selectively control a temperature of a region on the surface of the processing target substrate in a radial direction.

2. The semiconductor manufacturing apparatus of claim 1, wherein the temperature adjusters are Peltier devices.

3. The semiconductor manufacturing apparatus of claim 1, wherein the platen further comprises a thermometer configured to measure a temperature of the surface of the processing target substrate, and the temperatures of the temperature thermometer.

4. The semiconductor manufacturing apparatus of claim 3, wherein the thermometer is substantially at a center of the platen and substantially the same distance from temperature adjusters.

5. The semiconductor manufacturing apparatus of claim 3, further comprising a temperature controller determining the temperatures of the plurality of temperature adjusters on the basis of the information measured by the plurality of thermometers in order to keep the temperature of the surface of the processing target substrate substantially constant.

6. The semiconductor manufacturing apparatus of claim 4, further comprising a temperature controller determining the temperatures of the plurality of temperature adjusters on the basis of the information from the plurality of thermometers in order to keep the temperature of the surface of the processing target substrate substantially constant.

7. The semiconductor manufacturing apparatus of claim 1, further comprising a pressure adjuster configured to selectively adjust pressure to be applied from the presser onto the region.

8. The semiconductor manufacturing apparatus of claim 7, wherein the presser comprises an airbag.

9. The semiconductor manufacturing apparatus of claim 3, wherein the thermometer is an infrared thermometer.

10. The semiconductor manufacturing apparatus of claim 1, wherein the temperature of the temperature adjusters near the center of the processing target substrate is lower than the temperature of the temperature adjusters near circumferential regions on the surface of the processing target substrate.

11. The semiconductor manufacturing apparatus of claim 5, wherein the thermometer is configured to automatically measure the temperature of the surface of the processing target substrate and to transmit measurement data to the temperature controller.

12. The semiconductor manufacturing apparatus of claim 11, further comprising a memory configured to temporarily store the measurement data measured by the thermometer, a controller configured to determine the intensities of signals to the temperature adjusters on the basis of the measurement data, and a voltage converter configured to adjust supply voltages to the temperature adjusters on the basis of the signal intensities from the controller.

13. The semiconductor manufacturing apparatus of claim 1, wherein the temperature adjusters is configured to control the temperature of the surface of the processing target substrate in a range from 35° C. to 50° C.