JP2005005398A - Polisher and retainer ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage of the end of the groove of a retainer radial ring. <P>SOLUTION: The groove 22 is formed in radial on the bottom surface of a wear ring 21b, and an R portion 23 by which R processing is carried out is formed at the ends which accomplish acute angle by the inner peripheral surface side of the groove 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus and retainer ring, and is particularly suitable when applied to CMP (chemical mechanical polishing).
[0002]
[Prior art]
In recent semiconductor devices, CMP is used in order to flatten the surface of a wiring layer, an insulating layer, and the like after film formation and to perform focusing in a photolithography process with high accuracy.
Here, when CMP of a semiconductor wafer is performed, for example, as disclosed in Patent Document 1, retainer ring (also referred to as guide ring) is used to hold a semiconductor wafer on a polishing table. Yes.
[0003]
FIG. 8 is a perspective view showing a configuration of a conventional retainer ring.
In FIG. 8, the retainer ring 41 includes a support ring 41a for supporting the wear ring 41b and a wear ring 41b stacked on the support ring 41a. Grooves 42 are radially formed on the bottom surface of the wear ring 41b. . When CMP of the semiconductor wafer is performed, the semiconductor wafer surface is pressed onto the polishing table while the periphery of the semiconductor wafer is guided by the retainer ring 41 to flatten the semiconductor wafer surface.
[0004]
Here, when the semiconductor wafer surface is pressed onto the polishing table, the bottom surface of the wear ring 41b is also pressed onto the polishing table, and the bottom surface of the wear ring 41b is also scraped off. Then, the abrasive slurry supplied on the polishing table, the semiconductor wafer polishing debris, and the like can be taken in and out of the inner peripheral surface side of the retainer ring 41.
Further, when the semiconductor wafer is polished, the retainer ring 41 guides the semiconductor wafer while rotating together with the semiconductor wafer. For this reason, by forming the grooves 42 radially on the bottom surface of the wear ring 41b, it is possible to efficiently put in and out the abrasive slurry, polishing debris and the like through the grooves 42.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-25963
[Problems to be solved by the invention]
However, when the groove 42 is formed radially on the bottom surface of the wear ring 41b, the end 43 of the groove 42 has an acute angle. For this reason, there is a problem that the end portion 43 of the groove 42 is easily cracked, or the end portion 43 of the groove 42 scratches the polishing cloth, so that the polishing cloth is scratched and the polishing uniformity is deteriorated.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing apparatus and a retainer ring that can prevent damage to end portions of radially formed grooves.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, according to a polishing apparatus according to an aspect of the present invention, a polishing table, a polishing cloth attached to the polishing table, a rotating unit that rotates the polishing table, Slurry supply means for supplying slurry onto the polishing table, retainer rings for guiding the periphery of the wafer on the polishing table, and formed radially on the bottom surface of the retainer ring, with at least an end on the inner peripheral surface side having an obtuse angle And a polishing head for holding the wafer together with the retainer ring on the polishing table.
[0009]
This makes it possible to form a groove radially on the bottom surface of the retainer ring, while making it difficult to break the end of the groove, and to prevent the polishing cloth from being scratched at the end of the groove. It becomes possible. For this reason, even when the retainer ring is pressed onto the polishing cloth together with the semiconductor wafer, it becomes possible to polish the semiconductor wafer while allowing the abrasive slurry and polishing debris to be efficiently put in and out through the groove. It is possible to improve the uniformity of polishing.
[0010]
In addition, according to the polishing apparatus of one aspect of the present invention, the polishing table, the polishing cloth attached to the polishing table, the rotating means for rotating the polishing table, and the slurry are supplied onto the polishing table. A slurry supplying means, a retainer ring for guiding the periphery of the wafer on the polishing table, a groove formed radially on the bottom surface of the retainer ring, and an end portion forming an acute angle at least on the inner peripheral surface side of the groove. And a polishing head that holds the wafer together with the retainer ring on the polishing table.
[0011]
This makes it possible to form a groove radially on the bottom surface of the retainer ring, while making it difficult to break the end of the groove, and to prevent the polishing cloth from being scratched at the end of the groove. It becomes possible. For this reason, even when the retainer ring is pressed onto the polishing cloth together with the semiconductor wafer, it becomes possible to polish the semiconductor wafer while allowing the abrasive slurry and polishing debris to be efficiently put in and out through the groove. It is possible to improve the uniformity of polishing.
[0012]
The retainer ring according to one aspect of the present invention includes a groove that is formed radially on the bottom surface and configured so that at least an end portion on the inner peripheral surface side has an obtuse angle.
Thereby, even when the grooves are formed radially on the bottom surface of the retainer ring, at least the end portion forming an acute angle with respect to the rotation direction of the retainer ring can be removed. For this reason, it becomes possible to make it difficult to break the end portion of the groove, it is possible to prevent the polishing cloth from being scratched at the end portion of the groove, and to prevent the retainer ring and damage to the polishing cloth. It is possible to improve the uniformity of polishing.
[0013]
Moreover, according to the retainer ring which concerns on 1 aspect of this invention, it is provided with the groove | channel formed radially on the bottom face, and the rounded part provided in the edge part which comprises the acute angle of the inner peripheral surface side of the said groove | channel at least. Features.
Thereby, even when the grooves are formed radially on the bottom surface of the retainer ring, at least the end portion forming an acute angle with respect to the rotation direction of the retainer ring can be removed. For this reason, it becomes possible to make it difficult to break the end portion of the groove, it is possible to prevent the polishing cloth from being scratched at the end portion of the groove, and to prevent the retainer ring and damage to the polishing cloth. It is possible to improve the uniformity of polishing.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a polishing apparatus and a retainer ring according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a schematic configuration of a polishing apparatus according to a first embodiment of the present invention.
[0015]
In FIG. 1, a polishing table (also referred to as a platen) 1 is coupled to a rotating shaft 3 so as to be rotatable about the rotating shaft 3, and a polishing cloth 2 is attached on the polishing table 1. .
Further, a retainer ring 4 for guiding the periphery of the wafer W is provided on the polishing table 1 to which the polishing cloth 2 is attached, and a polishing head 5 for pressing the wafer W and the retainer ring 4 onto the polishing cloth 2 is provided. Is provided. Here, on the bottom surface of the retainer ring 4, grooves configured such that the end on the inner peripheral surface side has an obtuse angle are formed radially. A membrane 7 for adjusting the pressure of the wafer W is inserted between the polishing head 5 and the wafer W. The membrane 7 can be made of rubber or the like, for example. Examples of the wafer W to be polished include semiconductor wafers and glass wafers on which wiring layers such as Al, Cu, and polycrystalline silicon, and insulating layers such as silicon oxide films and silicon nitrogen films are formed. Can do.
[0016]
The polishing head 5 is coupled to the spindle 6 and is configured to rotate around the spindle 6 while pressing the wafer W and the retainer ring 4 onto the polishing cloth 2. In addition, a nozzle 8 for discharging an abrasive slurry 9 onto the polishing cloth 2 is provided above the polishing table 1.
When polishing the wafer W, the polishing cloth 2 is pasted on the polishing table 1, and the abrasive slurry 9 is discharged onto the polishing cloth 2. Then, the retainer ring 4 and the wafer W are pressed onto the polishing cloth 2 by the polishing head 5, and the polishing table 1 and the polishing head 5 are rotated while guiding the periphery of the wafer W with the retainer ring 4.
[0017]
Here, when the wafer W and the retainer ring 4 are pressed onto the polishing cloth 2, the polishing cloth 2 is compressed by the pressing of the wafer W and the retainer ring 4, and sinking occurs at the ends of the wafer W and the retainer ring 4. . For this reason, when the wafer W and the retainer ring 4 are pressed onto the polishing cloth 2, the thickness, material, and the like of the membrane 7 are adjusted so that the press of the retainer ring 4 is greater than the press of the wafer W. As a result, the amount of compression of the polishing cloth 2 at the position of the retainer ring 4 can be increased compared to the position of the wafer W, so that the sinking 10 of the polishing cloth 2 occurs at the end of the retainer ring 4. It is possible to prevent the polishing cloth 2 from sinking at the end of the wafer W. For this reason, the polishing cloth 2 can be uniformly applied to the entire surface of the wafer W, and the polishing uniformity of the wafer W can be improved.
[0018]
When the wafer W is pressed onto the polishing table 1, the bottom surface of the retainer ring 4 is also pressed onto the polishing table 1, and the bottom surface of the retainer ring 4 is also scraped off. Then, the abrasive slurry 9 supplied on the polishing table 1 and the shavings of the wafer W can be taken in and out of the inner peripheral surface side of the retainer ring 4 through a groove provided on the bottom surface of the retainer ring 4. .
[0019]
Here, by making the end on the inner peripheral surface side of the groove formed in the retainer ring 4 an obtuse angle, it is possible to form a groove radially on the bottom surface of the retainer ring 4 while breaking the end of the groove. It becomes possible to make it difficult, and it is possible to prevent the polishing cloth 2 from being scratched at the end of the groove. For this reason, even when the retainer ring 4 is pressed onto the polishing cloth 2 together with the semiconductor wafer W, the polishing cloth 2 and the retainer ring can be efficiently put in and out of the slurry through the grooves. 4 can be prevented from being damaged, and the polishing uniformity can be improved.
[0020]
FIG. 2A is a plan view showing the configuration of the retainer ring according to the second embodiment of the present invention, and FIG. 2B is a perspective view showing a part of FIG.
In FIG. 2, the retainer ring 21 includes a support ring 21a that supports the wear ring 21b, and a wear ring 21b that is stacked on the support ring 21a. Here, as a material of the support ring 21a, for example, stainless steel or the like can be used. The wear ring 21b guides the semiconductor wafer inside while being worn by the polishing cloth. For example, PPS (polyphenyl sulfite) can be used. A groove 22 is formed radially on the bottom surface of the wear ring 21b, and a rounded rounded portion 23 is provided at an end portion forming an acute angle on the inner peripheral surface side of the groove 22.
[0021]
The outer shape of the retainer ring 21 is, for example, 248 mm, the width of the retainer ring 21 is, for example, 24 mm, the width of the groove 22 is, for example, 3.2 mm, and the depth of the groove 22 is, for example, 2.7 mm. can do.
When polishing a semiconductor wafer, the semiconductor wafer and the retainer ring 21 are rotated on the polishing table while the periphery of the semiconductor wafer is guided by the retainer ring 21. Here, the bottom surface of the retainer ring 21 is pressed onto the polishing table together with the semiconductor wafer, and the slurry, polishing debris and the like supplied onto the polishing table are taken in and out of the inner peripheral surface side of the retainer ring 21 through the groove 22. be able to. As the semiconductor wafer is polished, the bottom surface of the retainer ring 21 is also polished, and the end of the groove 22 of the retainer ring 21 is rubbed against the polishing cloth.
[0022]
Here, by providing the rounded portion 23 at the end portion forming the acute angle on the inner peripheral surface side of the groove 22, the acute angle portion directed in the rotation direction of the retainer ring 21 can be removed. Therefore, even when the semiconductor wafer is polished while the bottom surface of the retainer ring 21 is rubbed against the polishing cloth, it is possible to suppress the polishing cloth from being damaged at the end of the groove 22. The lifetime can be increased, and the uniformity of polishing can be improved.
[0023]
In addition, in 2nd Embodiment mentioned above, in order to suppress that a grinding | polishing cloth is damaged at the edge part of the groove | channel 22, although the method of rounding the edge part which comprises the acute angle of the inner peripheral surface side of the groove | channel 22 was demonstrated. The end portion forming an acute angle on the inner peripheral surface side of the groove 22 may be chamfered.
FIG. 3A is a plan view showing the configuration of the retainer ring according to the third embodiment of the present invention, and FIG. 3B is a perspective view showing a part of FIG.
[0024]
In FIG. 3, the retainer ring 31 includes a support ring 31a that supports the wear ring 31b, and a wear ring 31b that is stacked on the support ring 31a. Here, as a material of the support ring 31a, for example, stainless steel or the like can be used. The wear ring 31b guides the semiconductor wafer inside while being worn by the polishing cloth. For example, PPS (polyphenyl sulfite) can be used. Grooves 32 are formed radially on the bottom surface of the wear ring 31b, and rounded round portions 33a and 33b are respectively provided at the ends of the grooves 32 forming acute angles on the inner peripheral surface side and the outer peripheral surface side. ing.
[0025]
The outer shape of the retainer ring 31 is, for example, 248 mm, the width of the retainer ring 31 is, for example, 24 mm, the width of the groove 32 is, for example, 3.2 mm, and the depth of the groove 32 is, for example, 2.7 mm. can do.
When polishing a semiconductor wafer, the semiconductor wafer and the retainer ring 31 are rotated on the polishing table while the periphery of the semiconductor wafer is guided by the retainer ring 31. Here, the bottom surface of the retainer ring 31 is pressed onto the polishing table together with the semiconductor wafer, and the slurry and polishing debris supplied onto the polishing table are put in and out of the inner peripheral surface side of the retainer ring 31 through the grooves 32. be able to. As the semiconductor wafer is polished, the bottom surface of the retainer ring 31 is also polished, and the end of the groove 32 of the retainer ring 31 is rubbed against the polishing cloth.
[0026]
Here, the acute angle portion of the retainer ring 31 can be removed by providing the rounded portions 33a and 33b at the ends of the groove 32 that form acute angles on the inner peripheral surface side and the outer peripheral surface side, respectively. Therefore, even when the semiconductor wafer is polished while the bottom surface of the retainer ring 31 is rubbed against the polishing cloth, it is possible to prevent the polishing cloth from being damaged at the end of the groove 32, and the groove It is possible to prevent the end portions of 32 from being lost, to increase the life of the polishing cloth and the retainer ring 31, and to improve the uniformity of polishing.
[0027]
In the third embodiment described above, in order to prevent the polishing cloth from being damaged at the end portion of the groove 32, the end portion forming the acute angle on the inner peripheral surface side and the outer peripheral surface side of the groove 32 is rounded. However, the ends of the grooves 22 that form acute angles on the inner peripheral surface side and the outer peripheral surface side may be chamfered.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a polishing apparatus according to a first embodiment.
FIG. 2 is a view showing a configuration of a retainer ring according to a second embodiment.
FIG. 3 is a view showing a configuration of a retainer ring according to a third embodiment.
FIG. 4 is a perspective view showing a configuration of a conventional retainer ring.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Polishing table, 2 Polishing cross, 3 Rotating shaft 4, 21, 31 Retainer ring, 5 Polishing head, 6 Spindle, 7 Membrane, 8 Nozzle, 9 Abrasive slurry 10 Submerged part, W wafer, 21a, 31a Support ring , 21b, 31b Wear ring, 22, 32 Groove, 23, 33

Claims (4)

A polishing table;
A polishing cloth affixed on the polishing table;
Rotating means for rotating the polishing table;
Slurry supply means for supplying slurry onto the polishing table;
Retainer ring for guiding the periphery of the wafer on the polishing table;
A groove formed radially on the bottom surface of the retainer ring, and configured so that at least an end portion on the inner peripheral surface side has an obtuse angle;
A polishing apparatus comprising: a polishing head that holds the wafer together with the retainer ring on the polishing table. A polishing table;
A polishing cloth affixed on the polishing table;
Rotating means for rotating the polishing table;
Slurry supply means for supplying slurry onto the polishing table;
Retainer ring for guiding the periphery of the wafer on the polishing table;
Grooves formed radially on the bottom surface of the retainer ring;
A rounded portion provided at an end portion forming an acute angle on at least the inner peripheral surface side of the groove;
A polishing apparatus comprising: a polishing head that holds the wafer together with the retainer ring on the polishing table. A retainer ring comprising grooves formed radially on a bottom surface and configured so that at least an end on an inner peripheral surface side has an obtuse angle. Grooves formed radially on the bottom surface;
A retainer ring comprising: a round portion provided at an end portion forming an acute angle at least on the inner peripheral surface side of the groove.

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