US20090075567A1

US20090075567A1 - Polishing pad conditioner and method for conditioning polishing pad

Info

Publication number: US20090075567A1
Application number: US12/022,166
Authority: US
Inventors: Ta-Jen Wang; Shing-I Chen; Ching-Chi Liu; Shuang-Hsun Chang
Original assignee: Powerchip Semiconductor Corp
Current assignee: Powerchip Semiconductor Corp
Priority date: 2007-09-19
Filing date: 2008-01-30
Publication date: 2009-03-19
Also published as: TW200914202A

Abstract

A polishing pad conditioner is provided. The polishing pad includes a substrate, at least one surface-conditioning unit, and at least one groove-cleaning unit. The surface-conditioning unit and the groove-cleaning unit are both disposed on a surface of the substrate. In addition, the surface-conditioning unit is integrally formed with the groove-cleaning unit form.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 96134871, filed on Sep. 19, 2007. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a chemical mechanical polishing apparatus and a method for maintenance of the chemical mechanical polishing apparatus, and more particularly, to a polishing pad conditioner and method for conditioning the polishing pad.
2. Description of Related Art
With the gradual reduction in the semiconductor device feature size to a deep sub-micron level, it becomes very important to provide an extremely planarized wafer surface or substrate surface during fabrication of an integrated circuit or other electronic devices to ensure the reliability of the semiconductor device.
In the semiconductor process, chemical mechanical polishing (CMP) is a currently commonly used global planarization technique. In general, during the process of chemical mechanical polishing, a wafer is held such that a surface of the wafer faces towards a speed-controlled polishing pad, with slurry containing chemical reagent and abrasive is supplied between the wafer and the polishing pad. Planarization of the wafer surface is thus achieved by relative movement between the wafer and the polishing pad. In other words, as the rotating wafer is being pressed against the rotating polishing pad, the wafer surface and the abrasive contact with each other and abrasion occurs therebetween, so that the wafer surface is abraded and hence gradually planarized.
However, after a long duration of chemical mechanical polishing process, the surface of the polishing pad may become glazed, and residual particles may be easily accumulated on the polishing pad. The particles may partly come from the abrasive of the slurry, and partly come from the by-products generated by film material abraded away from the wafer surface. Therefore, to ensure the quality of the chemical mechanical polishing process, a polishing pad conditioner is required to restore the appropriate roughness of the polishing pad such that the polishing pad can maintain the polishing rate and stability in polishing the wafer.
FIG. 1A is a cross-sectional view illustrating the polishing pad being conditioned with a conventional polishing pad conditioner. The polishing pad 100 forms a plurality of grooves 102 therein. The grooves 102 are used to uniformly distribute the slurry retained on the polishing pad 100 between the polishing pad 100 and a wafer to be polished. In addition, after a long duration of chemical mechanical polishing, residual particles 120 may be distributed over the polishing pad 100 and at bottoms of the grooves 102. On the other hand, the polishing pad 110 includes a substrate 112 and a plurality of diamond grits 114. The diamond grits 114 are disposed on the surface of the substrate 112 for abrading the surface of the polishing pad 100. When the polishing pad conditioner 110 is used to condition the polishing pad 100, the polishing pad 100 and the polishing pad conditioner 110 are rotated in respective predetermined directions, such that the rotating diamond grits 114 performs mechanical abrasion on the polishing pad 100 to remove deformed area on the surface of the polishing pad 100 and restore the slurry retention capability of the polishing pad 100. However, after several times of the conditioning by the polishing pad conditioner 110, the material of the polishing pad surface may be worn out resulting in reduction in the depth of the grooves 102 of the polishing pad 100. As a result, a clustered particle 122 formed by accumulation of the residual particles 120 can easily escape from the shallow grooves 102.
FIG. 1B is a cross-sectional view illustrating chemical mechanical polishing of a wafer using a polishing pad conditioned by the conventional polishing pad conditioner. After several times of conditioning, the grooves 102 of the polishing pad 100 may have large-sized clustered particles 122 accumulated therein, and the depth of the grooves 102 may be reduced. In chemical mechanical polishing of the wafer 130 using the polishing pad 100, the clustered particles 122 may escape from the shallow grooves 102 and move between the surface of the polishing pad 100 and the surface of the wafer 130. As a result, these clustered particles 122 may often cause micro-scratch 140 on the surface of the wafer 130 during the polishing process, thereby seriously affecting later processes.
Since the film planarity and uniformity of the wafer surface are dependent upon the characteristics of the polishing pad, effectively controlling structural and mechanical properties of the polishing pad can be very important to planarization of the wafer surface.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a polishing pad conditioner which can remove the accumulated residual particles at the time of conditioning the polishing pad.
The present invention is also directed to a method for conditioning a polishing pad, which can facilitate avoiding the accumulation of the residual particles on the polishing pad and prolong the lifespan of the polishing pad.
The present invention provides a polishing pad conditioner. The polishing pad conditioner includes a substrate, at least one surface-conditioning unit, and at least one groove-cleaning unit. The surface-conditioning unit and the groove-cleaning unit are both disposed on a surface of the substrate. In addition, the surface-conditioning unit and the groove-cleaning unit form an integral configuration.
According to one embodiment of the present invention, the groove-cleaning unit is, for example, a brush-like member.
According to one embodiment of the present invention, the material of the brush-like member is, for example, nylon.
According to one embodiment of the present invention, the groove-cleaning unit has, for example, any suitable configuration distributed on the surface of the substrate.
According to one embodiment of the present invention, the groove-cleaning units is arranged, for example, to surround an outer periphery of the surface-conditioning unit.
According to one embodiment of the present invention, the groove-cleaning units are, for example, arranged with the surface-conditioning units in an alternating manner.
According to one embodiment of the present invention, the surface conditioning unit includes, for example, a plurality of diamond grits.
The present invention also provides a method for conditioning a polishing pad. First, a polishing pad conditioner including at least one surface-conditioning unit and at least one groove-cleaning unit is provided. The surface-conditioning unit and the groove-cleaning unit are integrally formed and are disposed on a surface of the substrate. Next, the surface-conditioning unit and the groove-cleaning unit are made to contact each other. Next, the polishing pad conditioner and the polishing pad moved relative to each other so as to condition the polishing pad with the surface-conditioning unit, and removed residual particles on the polishing pad with the groove-cleaning unit, simultaneously.
According to one embodiment of the present invention, the groove-cleaning unit is, for example, a brush-like member.
According to one embodiment of the present invention, the material of the brush-like member includes, for example, nylon.
According to one embodiment of the present invention, the surface conditioning unit includes, for example, a plurality of diamond grits.
According to one embodiment of the present invention, the step of moving the polishing pad conditioner and the polishing pad relative to each other includes, for example, rotating the polishing pad conditioner and the polishing pad, respectively.
In the polishing pad conditioner of the present invention, the surface-conditioning unit is integrally formed with the groove-cleaning unit and are disposed on the substrate, such that the residual particles on the surface and in the grooves of the polishing pad can be wiped away using the groove-cleaning unit in simultaneity by abrading the surface of the polishing pad using the surface-conditioning unit. Therefore, the polishing pad conditioner of the present invention can effectively remove the residual particles from the polishing pad to avoid the generation of micro-scratch on a wafer to be polished.
In addition, the polishing pad conditioning method of the present invention performs conditioning the surface of the polishing pad and removing the residual particles simultaneously, thereby facilitating avoiding the accumulation of the residual particles in the grooves of the polishing pad, and effectively controlling the use condition of the polishing pad and prolonging the lifespan of the polishing pad.
In order to make the aforementioned and other features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view illustrating the polishing pad being treated with a conventional polishing pad conditioner.

FIG. 1B is a cross-sectional view illustrating chemical mechanical polishing of a wafer using a polishing pad conditioned by the conventional polishing pad conditioner.

FIG. 2A is a bottom view of a polishing pad conditioner in accordance with an embodiment of the present invention.

FIG. 2B is a cross-sectional view of FIG. 2A, taken along line I-I′ thereof.

FIGS. 3A to 3E are bottom views of polishing pad conditioners in accordance with other embodiments of the present invention, respectively.

FIG. 4 is a cross-sectional view illustrating conditioning of a polishing pad using a polishing pad conditioner in accordance with one embodiment of the present invention.

FIG. 5 illustrates a flow chart of polishing pad conditioning method in accordance with one embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

FIG. 2A is a bottom view of a polishing pad conditioner in accordance with an embodiment of the present invention. FIG. 2B is a cross-sectional view of FIG. 2A, taken along line I-I′ thereof.
Referring to FIGS. 2A and 2B, the polishing pad conditioner 200 may be used with various chemical mechanical polishing apparatus for conditioning a polishing pad (not shown) to restore the appropriate roughness, thereby maintaining high and stable polishing rate. The polishing pad conditioner 200 includes a substrate 202, at least one surface-conditioning unit 204, and at least one groove-cleaning unit 206. The substrate 202 is a disk-shaped member made from, for example, ceramic or stainless steel material. The surface-conditioning unit 204 and the groove-cleaning unit 206, for example, form an integral configuration disposed on the surface of the substrate 202.
As described above, the surface-conditioning unit 204 is used to perform mechanical abrasion on the polishing pad to remove the deformed area on the surface of the polishing pad, thereby restoring the appropriate roughness. The surface-conditioning unit 204 is formed, for example, by distributing a plurality of hard grits over the surface of the substrate 202. The hard grits may be diamond grits or ceramic grits, and set on the surface of the substrate 202, for example, by electroplating or sintering. The hard grits of the surface-conditioning unit 204 may be distributed in a random distribution manner, a uniform distribution manner, or in other suitable distribution manners.
In another embodiment, the surface-conditioning unit 204 may alternatively be a diamond-like carbon (DLC), and may be formed, for example, by forming a layer of DLC over the substrate 202 using a chemical vapour deposition (CVD) process, and then patterning the DLC according to a desired distributing range.
Referring to FIGS. 2A and 2B, the groove-cleaning unit 206 may be used, for example, to wipe away the residual particles accumulated on the surface and in the grooves of the polishing pad to thoroughly clean the polishing pad. The groove-cleaning unit 206 is, for example, a brush-like member that is neatly arranged on the surface of the substrate 202. The groove-cleaning unit 204 may use nylon, man-made fibre, plant fibre, carbon fibre, or the like, to form a brush hair-like or brush plate-like member. In addition, the groove-cleaning unit 206 is arranged, for example, to surround the surface-conditioning unit 204. That is, the groove-cleaning unit 206 is positioned on a circumferentially outer periphery of the surface of the substrate 202, and thus has an annular distribution.
Referring to FIG. 2A, in the present embodiment, the surface-conditioning unit 204 includes the plurality of hard grits distributed over the surface of the substrate 202 and has a solid round distribution, while the groove-cleaning unit 206 has an annular distribution over the surface of the substrate 202. In addition, the groove-cleaning unit 206 surrounds an outer periphery of the surface-conditioning unit 204, and is connected to the surface-conditioning unit 206 in an integral manner so as to collectively form a concentric round configuration. Therefore, when the polishing pad conditioner 200 is used to condition the polishing pad, the residual particles on the surface and in the grooves of the polishing pad can be wiped away using the groove-cleaning unit 206 in simultaneity with conditioning the surface of the polishing pad using the surface-conditioning unit 204, thereby improving the lifespan and performance of the polishing pad.
It should be noted that, in the above embodiment, the groove-cleaning unit 206 is described as surrounding the outer periphery of the surface-conditioning unit 204. However, the present invention should not be limited to this particular arrangement. In other embodiments, the groove-cleaning unit of the polishing pad conditioner may be formed in any suitable arrangements distributed over the surface of the substrate.
FIGS. 3A to 3E are bottom views of polishing pad conditioners in accordance with other embodiments of the present invention, respectively.
Referring to FIG. 3A, in the polishing pad conditioner 210, the groove-cleaning unit 216 has, for example, a round configuration. In the present embodiment, the round groove-cleaning unit 216 is symmetrically and uniformly disposed over the surface of the substrate 212, together with the surface-conditioning unit 214. Of course, in other embodiments, the groove-cleaning unit 216 may be oval, rectangular, triangular, rhombic, serrated in shape, or has other suitable irregular shape, and may be distributed over the surface of the substrate 212 in a random distribution manner.
Referring to FIG. 3B, in another embodiment, the groove-cleaning unit 226 and the surface-conditioning unit 224 of the polishing pad conditioner 220 may alternatively have strip distributions parallel to each other, and are arranged in an alternating manner over the surface of the substrate 222.
Referring to FIG. 3C, the surface of the substrate 232 of the polishing pad conditioner 230 may be divided into, for example, four equal areas, and the groove-cleaning unit 236 and the surface-conditioning unit 234 are alternately arranged over the surfaces of the substrates of the four equal areas.
Referring to FIG. 3D, in addition, in the polishing pad conditioner 240, the groove-cleaning unit 246 and the surface-conditioning unit 244 may be alternately arranged, and may extend radially from a geometric center toward an outer edge of the substrate 242 so as to form a whirlpool-like distribution on the surface of the substrate 242.
Referring to FIG. 3E, in the polishing pad conditioner 250, the groove-cleaning unit 256 may form, for example, a continuous spiral distribution on the surface of the substrate 252. The surface-conditioning unit 254 may be disposed, for example, over the remaining area of the surface of the substrate 252.
Referring to FIG. 3A to FIG. 3E, it should be noted that the surface- conditioning units 214, 224, 234, 244, 254 and respective groove-cleaning units 216, 226, 236, 246, 256 form integral configurations disposed on the surface of the substrate 212, 222, 232, 242, 252 and therefore, can remove and condition the surface of the polishing pad and wipe away the residual particles simultaneously, thereby improving the polishing characteristics of the polishing pad and prolonging the lifespan of the polishing pad.
In addition, the shape, material, quantity and distribution of the surface-conditioning unit and the groove-cleaning unit of the polishing pad conditioner are not limited to those described in the above embodiments. In addition to the above embodiments, the present invention may be embodied in other fashions, as long as the surface-conditioning unit and the groove-cleaning unit of the polishing pad conditioner form an integral configuration, the applications and variations of which should be known to those of ordinary skill in the art and is thus not described herein.
Next, a method for conditioning the polishing pad using the above-described polishing pad conditioner is described as follows. The method for conditioning the polishing pad of the present invention is described in the context of the polishing pad conditioner 200 shown in FIG. 2A. However, the following description is for the purpose of illustrating the present invention for those of ordinary skill in the art to understand and practice the present invention, and thus should not be regarded as limiting the scope of the present invention.
FIG. 4 is a cross-sectional view illustrating conditioning of a polishing pad using a polishing pad conditioner in accordance with one embodiment of the present invention. FIG. 5 illustrates a flow chart of polishing pad conditioning method in accordance with one embodiment of the present invention.
Referring to FIG. 4 and FIG. 5, in step S510, a polishing pad conditioner 200 including at least one surface-conditioning unit 204 and at least one groove-cleaning unit 206 is provided. The groove-cleaning unit 206 is arranged, for example, to surround an outer periphery of the surface-conditioning unit 204, and the surface-conditioning unit 204 and the groove-cleaning unit 206 form an integral configuration disposed on the surface of the substrate.
In step S520, the surface-conditioning unit 204 and the groove-cleaning unit 206 of the polishing pad conditioner 200 are brought into contact with the polishing pad 400.
Next, the polishing pad conditioner 200 and polishing pad 400 are rotated in respective predetermined directions. That is, the polishing pad conditioner 200 and polishing pad 400 in contact with each other are moved relative to one another to condition the polishing pad. The rotating directions of the polishing pad conditioner 200 and the polishing pad 400 may be the same or different. As the polishing pad conditioner 200 and the polishing pad 400 are moved relative to each other, the rotating surface-conditioning unit 204 will, for example, condition and remove deformed area on the surface of the polishing pad 400. At the same time, the groove-cleaning unit 206 will, for example, remove the residual particles 410 accumulated on the surface and in the grooves 402 of the polishing pad 400 (step S530).
It should be noted that, after being conditioned by the polishing pad conditioner 200, the surface of the polishing pad 400 may be have an appropriate roughness and restore the slurry retention capability, and at the same time, the excessive residual particles 410 may be removed and prevented from be accumulated in the grooves 402. Therefore, performing the chemical mechanical polishing of the wafer using the conditioned polishing pad 400 can provide high and stable polishing rate and effectively avoid generation of the micro-scratch on the wafer.
In summary, in the polishing pad conditioner of the present invention, the surface-conditioning unit may be integrally formed with the groove-cleaning unit and are disposed on the substrate, such that the residual particles on the surface and in the grooves of the polishing pad can be cleaned using the groove-cleaning unit in simultaneity with removal of the surface of the polishing pad using the surface-conditioning unit. Therefore, conditioning the polishing pad using the polishing pad conditioner of the present invention can assist the polishing pad in restoring the appropriate roughness and effectively remove the residual particles from the polishing pad to avoid the generation of micro-scratch on a wafer to be polished.
In addition, the polishing pad conditioning method of the present invention performs conditioning of the surface of the polishing pad and removal of the residual particles simultaneously to avoid the accumulation of the residual particles in the grooves of the polishing pad. As such, the method of the present invention can ensure the quality of the conditioned polishing pad, prolong the lifespan of the polishing pad, and avoid the generation of micro-scratch on the wafer.
On the other hand, the present invention can reduce a replacement rate of the polishing pad by effectively prolonging the lifespan of the polishing pad, thereby facilitating the cost reduction of equipment.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

1. A polishing pad conditioner, comprising:

a substrate;

at least one surface-conditioning unit disposed on a surface of the substrate; and

at least one groove-cleaning unit disposed on the surface of the substrate, wherein the surface-conditioning unit is integrally formed with the groove-cleaning unit.

2. The polishing pad conditioner in accordance with claim 1, wherein the groove-cleaning unit comprises a brush-like member.

3. The polishing pad conditioner in accordance with claim 2, wherein the material of the brush-like member comprises nylon.

4. The polishing pad conditioner in accordance with claim 1, wherein the groove-cleaning unit comprises a configuration on the surface of the substrate.

5. The polishing pad conditioner in accordance with claim 1, wherein the groove-cleaning units surrounds an outer periphery of the surface-conditioning unit.

6. The polishing pad conditioner in accordance with claim 1, wherein the groove-cleaning units are alternately arranged with the surface-conditioning units.

7. The polishing pad conditioner in accordance with claim 1, wherein the surface conditioning unit comprises a plurality of diamond grits.

8. A method for conditioning a polishing pad, comprising:

providing a polishing pad conditioner comprising at least one surface-conditioning unit and at least one groove-cleaning unit, wherein the surface-conditioning unit is integrally formed with the groove-cleaning unit;

bringing the surface-conditioning unit and the groove-cleaning unit into contact with each other; and

moving the polishing pad conditioner and the polishing pad relative to each other so as to condition the polishing pad with the surface-conditioning unit, and removing residual particles on the polishing pad with the groove-cleaning unit, simultaneously.

9. The method for conditioning a polishing pad in accordance with claim 8, wherein the groove-cleaning unit comprises a brush-like member.

10. The method for conditioning a polishing pad in accordance with claim 9, wherein the material of the brush-like member comprises nylon.

11. The method for conditioning a polishing pad in accordance with claim 8, wherein the surface-conditioning unit comprises a plurality of diamond grits.

12. The method for conditioning a polishing pad in accordance with claim 8, wherein the step of moving the polishing pad conditioner and the polishing pad relative to each other comprises rotating the polishing pad conditioner and the polishing pad, respectively.