US20070224920A1

US20070224920A1 - Polishing pad, method of polishing and polishing apparatus

Info

Publication number: US20070224920A1
Application number: US11/691,566
Authority: US
Inventors: Yasutada Nakagawa; Eijiro Koike
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2006-03-27
Filing date: 2007-03-27
Publication date: 2007-09-27
Also published as: CN101045290A; TW200736001A; KR100862130B1; KR20070096934A

Abstract

A polishing pad according to the invention comprises a pad body having a polishing surface and a support surface and a plurality of hole apertures extending from the polishing surface to the support surface, each of the plurality of apertures having a noncircular shaped opening oriented at a predetermined angle with respect to a radial direction of the polishing pad.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2006-86087, filed on Mar. 27, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a polishing pad, a method of polishing and a polishing apparatus for polishing a semiconductor wafer, which are used for a chemical and mechanical polishing (CMP) work in a process of manufacturing semiconductor devices. More particularly, the invention relates to a polishing pad, method of polishing and a polishing apparatus which facilitate a feed flow of a slurry liquid to the polishing pad for a semiconductor wafer.
2. Description of the Related Art
In a process of manufacturing semiconductor devices, a CMP work is carried out to polish and flatten dielectrics surface of a wafer. A polishing pad is used for flattening the dielectrics surface. A polishing surface of the polishing pad for use in the CMP work is planar. A surface of the wafer to be polished and the polishing surface of the polishing pad are arranged in parallel to each other. Thus, the wafer surface and the polishing surface are arranged in contact with each other and both are rotated for polishing. Various types of polishing apparatuses are used.
For example, a polishing pad 100 as shown in FIG. 19 has a flexible pad 101 and a body pad 102. The body pad 102 is made of a hard material, foamed urethane, or the like. The body pad 102 has a number of through holes or apertures, which pass through the body pad.
A polishing pad 110 as shown in FIG. 20 has a flexible pad 111, a body pad 112, through holes 113 and lattice like polishing grooves 114. The grooves supply and remove an abrasive liquid or slurry and to effectively removes a polishing waste. A polishing pad 112 having polishing grooves 114 formed therein has a high ability to supply and remove the abrasive liquid.
Therefore, such a pad is advantageous in that polishing amount variations between the central part and the peripheral end part of the wafer are small. The polishing pad is advantageous in that it is easy to peel the wafer from the polishing pad since air can enter between the center of the wafer and the pad through the grooves.
Variety shapes of through holes are developed to supply and remove a slurry and to effectively remove a polishing waste(refer to, for example, Jpn. Pat. Appln. KOKAI Publication No. 2004-71985 and Jpn. Pat. Appln. KOKAI Publication No. 2003-300149).
However, this type of polishing pad suffers from the following problems. A pad body 102 which has only through holes 103 is not easy to bring forward to feed liquid. On the other hand, a pad body 112 which has only polishing grooves 114 can bring forward to feed liquid into a wafer. However, the depth of the polishing grooves 114 is shorter than the depth of through holes 103. Therefore, the polishing pad with the pad body 112 is short life.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a polishing pad which can polish a wafer evenly with small variations of polishing amount. It is an object of the present invention to provide a method of polishing which can polish a wafer evenly with small variations of polishing amount. It is an object of the present invention to provide a polishing apparatus which can polish a wafer evenly with small variations polishing amount.

(1)According to one embodiment of the present invention, a polishing pad for polishing an object including a pad body having a polishing surface and a support surface and a plurality of hole apertures extending from the polishing surface to the support surface, each of the plurality of apertures having a noncircular shaped opening oriented at a predetermined angle with respect to a radial direction of the polishing pad.
(2) According to another embodiment of the present invention, a polishing apparatus for polishing an object including a holder mechanism configured to hold the object, a polishing pad configured to be arranged to face the be-polished object hold by the holder mechanism, the polishing pad including a plate-like pad having a polishing surface and a support surface, a drive mechanism to rotate the polishing pad a plurality of hole apertures extending from the polishing surface to the support surface, each of the plurality of apertures having a noncircular shaped opening oriented at a predetermined angle with respect to a radial direction of the polishing pad.
(3) According to another embodiment of the present invention, a method of polishing an object including holding the object and pressing a polishing pad in contact with the object rotating the polishing pad, the polishing pad including a pad body having a polishing surface and a support surface and a plurality of hole apertures extending from the polishing surface to the support surface, each of the plurality of apertures having a noncircular shaped opening oriented at a predetermined angle with respect to a radial direction of the polishing pad.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
FIG. 1 is a schematic view of a polishing apparatus having a polishing pad in accordance with one embodiment of the invention.
FIG. 2 is a plan view showing the polishing pad in accordance with one embodiment of the invention.
FIG. 3 is a plan view showing through holes of the polishing pad in accordance with one embodiment of the invention.
FIG. 4 is a graph showing a relationship between the polishing rate and the proportion of major axis of the through hole in accordance with one embodiment of the invention.
FIG. 5 is a plan view showing a polishing pad in accordance with another embodiment of the invention.
FIG. 6 is an explanatory view showing positional relation of the through hole in FIG. 5
FIG. 7 is an explanatory view showing relation of polishing rate in accordance with another embodiment of the invention.
FIG. 8 is a plan view showing a polishing pad in accordance with another embodiment of the invention.
FIG. 9 is an explanatory view showing positional relation of the through hole in FIG. 8.
FIG. 10 is an explanatory view showing a relation of polishing rate and a proportion of major axis to minor axis of the through hole in accordance with another embodiment of the invention.
FIG. 11 is a plan view showing a polishing pad in accordance with another embodiment of the invention.
FIG. 12 is a plan view showing a polishing pad in accordance with another embodiment of the invention.
FIG. 13 is an explanatory view showing positional relation of a through hole and a central of the polishing pad in accordance with another embodiment of the invention.
FIG. 14 is an explanatory view showing relation of polishing rate and angle in accordance with another embodiment of the invention.
FIG. 15 is a plan view showing a polishing pad in accordance with another embodiment of the invention.
FIG. 16 is a plan view showing a polishing pad in accordance with another embodiment of the invention.
FIG. 17 is an explanatory view showing positional relation of a through hole and a central of the polishing pad in accordance with another embodiment of the invention.
FIG. 18 is a plan view showing a polishing pad in accordance with another embodiment of the invention.
FIG. 19 is a cross sectional view showing a polishing pad.
FIG. 20 is a cross sectional view showing a polishing pad.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a structural view showing a polishing apparatus 100 set up a polishing pad 10, which is a first embodiment of the present invention. FIG. 2 is a plan view showing the polishing pad 10. FIG. 3 is a plan view showing through holes 20 which is provided on the polishing pad 10. X is a rotating center on the polishing pad 10, F is a flowing direction of abrasive liquid and P is a rotating direction of the polishing pad 10.
The polishing apparatus 100 has the polishing pad 10, a holder mechanism 110 providing a wafer w and a rotary drive mechanism 120 which rotates the polishing pad 10, as shown in FIG. 1.
The polishing pad 10 is laminated with a soft pad 11 and a pad body 12. The pad body 12 is made of hard resin such as formed polyurethane or urethane.
The pad body 12 is provided with the through holes 20. The through holes 20 are provided from a polishing surface 12 a to a support surface 12 b, in other words, in the thickness direction of the pad body 12. The through holes 20 formed by such as a punching process or a nesting block.
A predetermined number of the through holes 20 are provided in approximately a concentric fashion on the polishing body 12, as shown in the embodiment illustrated in FIG. 2. The through holes 20 is provided in approximately a concentric fashion with respect to the rotating center X on the polishing pad 10 when a to-be-polished object is polished, too. The through holes 20 are noncircular shaped openings. The through holes 20 are provided in a predetermined angle with respect to a radial direction. It is better that all of the through holes 20 are provided in the same predetermined angle. However, if there is a positive effect, all of the through holes 20 don't need to be same angle.
The through holes 20 may be elliptical, as shown in FIG. 3. The elliptical shape of the holes has a minor axis a and a major axis b. The rotating center X is provided on a line extending from the minor axis.
In one embodiment, the through holes 20 may be provided at 1-10 per 1 cm2. One of a dimension of the through holes 20 is 1-6 mm2. A surface ratio of the through holes 20 with respect to the surface area of the pad body 12 may be 1-60 percent.
The through holes 20 are provided along a line on which the abrasive liquid flows or travels. It is easy to flow out abrasive liquid which is in the through holes 20. As a result, it promotes to feed and exhaust the abrasive liquid, and a polishing rate rises. And a life of the polishing pad 10 does not change compared with a life of using only prior through holes.
A polishing rate rises to increase b/a (a rate of major axis for a minor axis), as shown in FIG. 4. For example, in case of b/a=1.2, a polishing rate rises about 10 percent compared with prior through holes (b/a=1).
According to the embodiment of the polishing pad 10, it can promote to feed and exhaust the abrasive liquid. And the polishing rate can rise.
FIG. 5 is a plan view showing a polishing pad 10A which is a second embodiment of the present invention. FIG. 6 is a showing relationship between the through holes 20 and the rotating center X. In FIG. 5 and FIG. 6, the same functional parts showing in FIG. 2 and FIG. 3 are given the same number and overlapping explanation is skipped.
For the polishing pad 10A, which is one embodiment of the present invention, the major axis of the through holes 20 is provided at a predetermined angle θ with respect to the radial direction R. The through holes 20 can promote to feed and exhaust the abrasive liquid with centrifugal force.
FIG. 7 shows a change in polishing rate when angle θ is changed from 0 degree to 90 degree. When angle θ is 90 degree in FIG. 2, the minor direction is accorded with the diameter direction R. When angle θ is from 40 degree to 80 degree, the polishing rate is maximum. The maximum polishing rate is twice as the polishing rate in FIG. 2. Angle θ of the maximum polishing rate change according to rotary speed of a polishing pad.
The polishing pad 10A can promote to feed and exhaust the abrasive liquid and improve the polishing rate.
FIG. 8 is a plan view showing a polishing pad 10B which is a third embodiment of the present invention. FIG. 9 shows relationship between the through holes 30 and the rotating center X of the polishing pad 10B. In FIG. 8 and FIG. 9, the same functional parts showing in FIG. 2 and FIG. 3 are given the same number and overlapping explanation is skipped.
On the polishing pad 10B of the embodiment of the present invention, the through holes 30 are provided. The through holes 30 are teardrop shape which shape is wider down stream area than up stream side.
A polishing rate rises to increase d/c (a rate of major axis for a minor axis), as shown in FIG. 10. For example, in case of d/c=1.2, a polishing rate rises about 5 percent compared with prior through holes (b/a=1).
FIG. 11 is a plan view showing a polishing pad 10C which is a forth embodiment of the present invention. In FIG. 11, the same functional parts showing in FIG. 8 are given the same number and overlapping explanation is skipped.
On the polishing pad 10C of the embodiment of the present invention, a down stream side of the through holes 30 is angled outwardly, away from the center of the pad. In this arrangement, the through holes 30 can promote to supply and drain the abrasive liquid by a centrifugal force.
FIG. 12 is a plan view showing a polishing pad 10D which is a fifth embodiment of the present invention. FIG. 13 shows relationship between the through holes 40 and the rotating center X of the polishing pad 10B. In FIG. 12 and FIG. 13, the same functional parts showing in FIG. 2 and FIG. 3 are given the same number and overlapping explanation is skipped.
On the polishing pad 10D of the embodiment of the present invention, through holes 40 are provided. The through holes 40 are teardrop shape which shape is gradually wider down stream area than up stream side. Down stream area of through holes 40 are provided to be leaned φ degree to inner circumference configuration.
As shown in FIG. 14, a polishing rate rises to adjust φ degree. For example, when φ is provided more than 20 degree, a polishing rate rises about 5 percent compared with through holes 30 which are teardrop shape.
FIG. 15 is a plan view showing a polishing pad 10E which is a sixth embodiment of the present invention. In FIG. 15, the same functional parts showing in FIG. 12 are given the same number and overlapping explanation is skipped.
On the polishing pad 10E of the embodiment of the present invention, the through holes 40 are provided to be leaned for circumferential direction. In other words, a down stream area of the abrasive liquid, a side of the through holes 30 provided to be out side direction on the polishing pad 10E.
The through holes 40 can nurture to feed and exhaust the abrasive liquid with centrifugal force.
FIG. 16 is a plan view showing a polishing pad 10F which is a seventh embodiment of the present invention. FIG. 17 is a showing relationship between the through holes 50 and the rotating center X of the polishing pad 10B.
In FIG. 16 and FIG. 17, the same reference numeral as in FIG. 2 and 3 are used for the same functional parts, and their explanations are omitted.
On the polishing pad 10F of the embodiment of the present invention, the through holes 50 are provided. The through holes 50 are teardrop shape having a down stream area gradually wider than an up stream side. Down stream area of through holes 50 is angled outwardly at φ degree with respect to the up stream side. Outer configuration is defined as below zero.
A polishing rate rises to adjust φ degree. For example, when φ is provided more than −20 degree, a polishing rate rises about 5 percent compared with through holes 30 which are teardrop shape.
FIG. 18 is a plan view showing a polishing pad 10G which is a eighth embodiment of the present invention.
In FIG. 18, the same functional parts showing in FIG. 16 are given the same number and overlapping explanation is skipped.
In one embodiment, for the polishing pad 10G, the through holes 50 are provided to be leaned for circumferential direction. In other words, the through holes 50 are provided to be leaned to out side direction on down stream area of the abrasive liquid. The through holes 50 can nurture to feed and exhaust the abrasive liquid with centrifugal force.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Claims

1. A polishing pad for polishing an object, comprising:

a pad body having a polishing surface and a support surface; and

a plurality of hole apertures extending from the polishing surface to the support surface, each of the plurality of apertures having a noncircular shaped opening oriented at a predetermined angle with respect to a radial direction of the polishing pad.

2. The polishing pad according to claim 1, wherein the opening has an elliptical shape.

3. The polishing pad according to claim 1, wherein the opening includes a part having a gradually widening width in a predetermined direction with respect to the radial direction.

4. The polishing pad according to claim 2, wherein the opening has a major axis thereof angled with respect to the radial direction.

5. The polishing pad according to claim 3, wherein the opening has a major axis thereof angled with respect to the radial direction.

6. The polishing pad according to claim 1, wherein the opening includes a part having a gradually widening width in a predetermined direction with respect to the radial direction, the opening having a down stream side curving inwardly.

7. The polishing pad according to claim 1, wherein the opening includes a part having a gradually widening width in a predetermined direction with respect to the radial direction, the opening having a down stream side curving outwardly.

8. The polishing pad according to claim 6, wherein the opening has a major axis thereof angled with respect to the radial direction.

9. The polishing pad according to claim 2, wherein the opening has a major axis thereof angled with respect to the radial direction.

10. a polishing pad configured to be arranged to face the be-polished object hold by the holder mechanism, the polishing pad including a plate-like pad having a polishing surface and a support surface;

a drive mechanism to rotate the polishing pad;

11. The polishing apparatus according to claim 10, wherein the opening has an elliptical shape.

12. The polishing apparatus according to claim 10, wherein the opening includes a part having a gradually widening width in a predetermined direction with respect to the radial direction.

13. The polishing apparatus according to claim 11, wherein the opening has a major axis thereof angled with respect to the radial direction.

14. A method of polishing an object, comprising:

holding the object; and

pressing a polishing pad in contact with the object;

the polishing pad including a pad body having a polishing surface and a support surface; and

15. The polishing method according to claim 14, wherein the opening has an elliptical shape.

16. The polishing method according to claim 14, wherein the opening includes a part having a gradually widening width in a predetermined direction with respect to the radial direction.

17. The polishing method according to claim 16, wherein the opening has a major axis thereof angled with respect to the radial direction.