US20070224923A1

US20070224923A1 - Polishing pad, chemical mechanical polishing apparatus and method for manufacturing polishing pad

Info

Publication number: US20070224923A1
Application number: US11/727,300
Authority: US
Inventors: Masafumi Shiratani
Original assignee: NEC Electronics Corp
Current assignee: NEC Electronics Corp
Priority date: 2006-03-27
Filing date: 2007-03-26
Publication date: 2007-09-27
Also published as: JP2007266052A

Abstract

A polishing pad with reduced cost and easy manufacturability without waste is provided. A disc-shaped polishing layer 31 having a plurality of through holes 34 formed therein, an adhesive layer 33 provided only in a position in a back surface of the polishing layer 31 where no through hole 34 is formed and a disc-shaped support plate 32 having a flat surface, which is joined to the back surface of the polishing layer 31 by the adhesive layer 33 are provided. Since an adhesive layer 33 is not exposed to bottoms of the through holes 34 of the polishing layer 31, acting the slurry over the adhesive layer 33 to strip the polishing layer 31 from the support plate 32 is inhibited. Since the through holes 34 formed in the polishing layer 31 do not extend to the support plate 32, a decrease in the mechanical strength is not caused.

Description

This application is based on Japanese patent application No. 2006-85,312, the content of which is incorporated hereinto by reference.

BACKGROUND

1. Technical Field
The present invention relates to a polishing pad utilized in a chemical mechanical polishing (CMP) process, and particularly relates to a polishing pad having a multiple-layered structure, in which a support plate is joined to a polishing layer having a plurality of through holes formed therein, a CMP apparatus having such polishing pad and a method for manufacturing such polishing pad.
2. Related Art
Currently, in processes for manufacturing semiconductor devices, a chemical mechanical polishing (CMP) process may be often performed for providing finer planarized surfaces. In such CMP process, a disc-shaped polishing pad is supported by a shaft, and is driven to be rotated, while a slurry is supplied to such polishing pad that is driven to be rotated. A workpiece is compressing-contacted with the surface of the polishing pad in such condition to planarize the surface of the workpiece.
Better retaining-ability of a slurry is required for the polishing pad utilized in such CMP process. Thus, as shown in FIG. 4 and FIG. 5, an approach of providing a polishing pad 10 having a multiple-layered structure of a support plate 12 and a polishing layer 11, surface of which is provided with a large number of through holes 13 formed therein. In such polishing pad 10, the polishing layer 11 is joined to the support plate 12 by an adhesive layer 14.
Here, a first conventional example of a method for manufacturing a polishing pad 10 is described as follows in reference to FIGS. 6A to 6D. First of all, a disc-shaped polishing layer 11 is prepared as shown in FIG. 6A, and through holes 13 are formed in such polishing layer 11 by a punching processing as shown in FIG. 6B.
Then, as shown in FIG. 6C, a disc-shaped support plate 12 is prepared, and an adhesive layer 14 is provided over the surface thereof. The adhesive layer 14 may be formed by, for example, an application of an adhesive agent, or pasting tapes on both sides thereof. Then, as shown in FIG. 6D, a back surface of the polishing layer 11 is joined to a surface of the support plate 12 by the adhesive layer 14 to provide a finished product of the polishing pad 10 (see, for example, Japanese Patent Laid-Open No. H09-117,855 (1997)).
In addition, a second conventional example of a method for manufacturing a polishing pad is described as follows in reference to FIGS. 7A to 7D. First of all, a disc-shaped polishing layer 21 is prepared as shown in FIG. 7A, and a disc-shaped support plate 22 is prepared, as shown in FIG. 7B.
Next, as shown in FIG. 7C, the polishing layer 21 is joined to the support plate 22 by an adhesive layer 24. Then, as shown in FIG. 7D, through holes 23 extending through the polishing layer 21 from the surface thereof are formed to provide a finished product of the polishing pad 20 (see, for example, Japanese Patent Laid-Open No. H11-156,699 (1999)).
In addition to above, through holes 13 and 23 of the polishing layer 11 and 21 as described above may be formed as circular small holes as shown in FIG. 4, or may be formed as linear concave trenches (not shown).
In the polishing pad 10 produced by the above described first method for manufacturing the polishing pad, as shown in FIG. 5 and FIG. 6D, an adhesive layer 14 is partially exposed in the bottom of the through holes 13. Thus, the slurry acts on the adhesive layer 14 and degrades the adhesive strength such that the polishing layer 11 is easily flaked off from the support plate 12. Further, if the flaked adhesive layer 14 is mixed into the slurry, a failure is caused in the workpiece.
On the other hand, in the polishing pad 20 produced by the above-described second method for manufacturing the polishing pad, it is difficult to form the through holes 23 only in the polishing layer 21. Thus, as shown in FIG. 7D, the through holes 23 are necessarily formed so as to reach to the support plate 22, providing a deteriorated mechanical strength of the polishing pad 20.
In addition, as shown in FIG. 7C, through holes 23 are not yet formed at the time the support plate 22 is joined to the polishing layer 21. Thus, it is impossible to eliminate air trapped in the adhesive layer 24 through the through hole 23 while joining the polishing layer 21 to the support plate 22. This leads joining the polishing layer 21 to the support plate 22 while air is remained in the adhesive layer 24, providing a reduced bonding strength.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a polishing pad having a multiple-layered structure and being utilized in a chemical mechanical polishing (CMP) process, comprising: a disc-shaped polishing layer having a plurality of through holes formed to extend from a front surface to a back surface thereof; an adhesive layer provided only in a position in a back surface of the polishing layer where the through hole is not formed; and a disc-shaped support plate having a flat surface, which is joined to the back surface of the polishing layer by the adhesive layer.
Since an adhesive layer is not exposed to the bottoms of the through holes of the polishing layer, the degradation of the adhesive strength by the slurry is inhibited. And since the through holes formed in the polishing layer do not extend to the support plate, a decrease in the mechanical strength is not caused.
According to another aspect of the present invention, there is provided a chemical mechanical polishing (CMP) apparatus for performing a CMP process applied to a workpiece utilizing a polishing pad, comprising: a polishing pad according to the present invention; a disc-shaped platen having a front surface, which is joined to a back surface of the polishing pad; a pad actuating unit for rotating the polishing pad joined on the platen; a slurry supplying unit for supplying a slurry to the polishing pad that is actuated to be rotated; and a workpiece pressing unit for supporting the workpiece and pressing the workpiece to the polishing pad that is actuated to be rotated. Thus, since the CMP apparatus of the present invention is capable of polishing a workpiece utilizing the polishing pad according to the present invention, acting the slurry over the adhesive layer of the polishing pad and the degradation of the adhesive strength by the slurry is inhibited.
According to further aspect of the present invention, there is provided a method for manufacturing a polishing pad, which is utilized in a chemical mechanical polishing (CMP) process, including: providing an adhesive layer and a stripping form on a back surface of a disc-shaped polishing layer having a front surface serving as a polishing surface; forming a plurality of through holes, which extend from a surface of the polishing layer through the adhesive layer to a back surface of the stripping form; stripping the stripping form from the back surface of the polishing layer having the plurality of through holes formed therein; and joining the back surface of the polishing layer exposed by stripping the stripping form to a surface of a support plate by the adhesive layer.
Since the polishing pad is produced to have a structure that prevents exposing the adhesive layer in the bottoms of the through holes of the polishing layer in the method for manufacturing the polishing pad of the present invention, the polishing pad that prevents acting the slurry over the adhesive layer of the polishing pad is produced, and since the through holes formed in the polishing layer do not reach to the support plate, the polishing pad having an improved mechanical strength is produced.
In addition to above, the term “flat surface” appeared in claims and the description of the present invention means a surface that is physically formed for the aim of creating a flat surface, and of course it is necessary to be a geometric completely flat plane.
Since an adhesive layer is not exposed to bottoms of through holes of the polishing layer, acting the slurry over the adhesive layer and the degradation of the adhesive strength by the slurry is inhibited, so that a peeling off of the polishing layer from the support plate can be prevented. And since through holes formed in the polishing layer do not extend to the support plate, a decrease in the mechanical strength is prevented, so that an improved polishing of the workpiece can be presented.
Since the CMP apparatus of the present invention is capable of polishing a workpiece utilizing the polishing pad according to the present invention, acting the slurry over the adhesive layer of the polishing pad and the degradation of the adhesive strength by the slurry is inhibited, so that an improved polishing of the workpiece can be presented without causing a peeling off of the polishing layer from the support plate.
Since the polishing pad can be produced to have a structure that prevents exposing the adhesive layer in the bottoms of the through holes of the polishing layer in the method for manufacturing the polishing pad of the present invention, there can produce the polishing pad that prevents acting the slurry over the adhesive layer of the polishing pad and the degradation of the adhesive strength by the slurry. And since the through holes formed in the polishing layer do not reach to the support plate, the polishing pad having an improved mechanical strength can be produced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic vertical cross-sectional view, showing a structure of a main part of a polishing pad in an embodiment of the present invention;

FIGS. 2A to 2E are a schematic vertical cross-sectional views, illustrating operations of a method for manufacturing the polishing pad according to the present invention;

FIG. 3A is a schematic side view, showing a condition of mounting a polishing pad of the present embodiment onto a platen of a CMP apparatus, and FIG. 3B is a schematic side view, showing a condition of mounting a conventional polishing pad onto a platen of a CMP apparatus;

FIG. 4 is a plan view, showing an appearance of a conventional polishing pad;

FIG. 5 is a schematic vertical cross-section view, showing a structure of a main part of a conventional polishing pad;

FIGS. 6A to 6D are vertical cross-section views, illustrating operations of a first conventional method for manufacturing a conventional polishing pad; and

FIGS. 7A to 7D are vertical cross-section views, illustrating operations of a second conventional method for manufacturing a conventional polishing pad.

DETAILED DESCRIPTION

The invention will be now described herein with reference to illustrative embodiments. Those skilled in the art will recognize that many alternative embodiments can be accomplished using the teachings of the present invention and that the invention is not limited to the embodiments illustrated for explanatory purposed.
Preferable embodiments of the present invention will be described as follows in further detail, in reference to FIG. 1, FIGS. 2A to 2E and FIGS. 3A and 3B. In all figures, identical numeral is assigned to an element commonly appeared in both of the description of the present invention the description of the related art, and the detailed description thereof will not be repeated.
A polishing pad 30 of the present embodiment is formed to have a dual-layer structure, which is one of typical multiple-layered structure. Thus, as shown in FIG. 1, a disc-shaped support plate 32 is joined to a disc-shaped polishing layer 31 by an adhesive layer 33.
A plurality of through holes 34 composed of circular small holes are formed to extend from a front surface to a back surface of the polishing layer 31. The adhesive layer 33 is provided on the back surface of the polishing layer 31 only in a position where no through hole 34 is formed.
Now, a method for manufacturing the polishing pad 30 of the present embodiment will be described in reference to FIGS. 2A to 2E. First of all, the disc-shaped polishing layer 31 is prepared as shown in FIG. 2A, and the adhesive layer 33 and a stripping form 36 are provided on the back surface thereof as shown in FIG. 2B.
More specifically, a two-sided tape (not shown) having the adhesive layer 33, which is provided with stripping forms 36 affixed on both sides thereof, is prepared. Only a stripping form 36 in the side of the front surface of the two-sided tape is stripped to expose the adhesive layer 33.
The front surface of such adhesive layer 33 is pasted on the back surface of the polishing layer 31, so that the adhesive layer 33 and the stripping form 36 are provided on the polishing layer 31. In such condition, as shown in FIG. 2C, a plurality of through holes 34 are formed in the polishing layer 31, the adhesive layer 33 and the stripping form 36.
In next, as shown in FIG. 2D, the stripping form 36 is stripped from the back surface of the polishing layer 31, which is provided with a plurality of through holes 34 formed therein. Then, as shown in FIG. 2E, a front surface of the support plate 32 is joined to the back surface of polishing layer 31 exposed by stripping the stripping form 36 by the adhesive layer 33 to complete the manufacture of the polishing pad 30.
The polishing pad 30 produced by the method for manufacturing the polishing pad as described above is utilized in a CMP process for workpieces as a part of the CMP apparatus 40, as shown in FIG. 3A. Such CMP apparatus 40 includes, for example, a platen 41, a pad actuating unit 42, a slurry supplying unit 43, a workpiece pressing unit (not shown) and the like.
The platen 41 is formed to have a disc-shape, which is the same as the two-dimensional geometry of the polishing pad 30. The polishing pad 30 is mounted in a replaceable manner on the front surface of the platen 41 by an adhesive agent or a two-sided tape. The pad actuating unit 42 actuates a rotation of the platen 41 to rotate the polishing pad 30 that is joined on the surface thereof.
The slurry supplying unit 43 supplies a slurry S to the rotating polishing pad 30. The workpiece pressing unit functions as supporting the workpiece and compressing-contacting thereof with the rotating polishing pad 30. In the CMP apparatus 40 having such structure, the workpiece can be CMP processed utilizing the polishing pad 30.
In the polishing pad 30 produced by the method for manufacturing the polishing pad of the present embodiment, as shown in FIG. 2E and FIG. 1, an exposure of the adhesive layer 33 in the bottoms of the through holes 34 is prevented. Thus, unwanted peeling-off of the polishing layer 31 from the support plate 32 due to acting of the slurry S over the adhesive layer 33 can be sufficiently prevented.
Further, a failure of a workpiece due to a contamination of the flaked adhesive layer 33 into the slurry S can be sufficiently prevented. In addition, since the through holes 34 are not formed to extend to the support plate 32, a decrease in the mechanical strength thereof can also be prevented.
Moreover, in the method for manufacturing the polishing pad according to the present embodiment, as shown in FIG. 2C to FIG. 2E, the through holes 34 are formed at the time when the polishing layer 31 is joining to the support plate 32. Air trapped in the adhesive layer 33 can be removed via the through holes 34, while the polishing layer 31 is joining to the support plate 32. Therefore, the polishing layer 31 can be joined to the support plate 32 without remained air in the adhesive layer 33, thereby ensuring an improved bonding strength therebetween.
In addition, in the method for manufacturing the polishing pad of the present embodiment, the through holes 34 are formed, after the adhesive layer 33 and the stripping form 36 on the back surface of the polishing layer 31 are provided, as described above. Thus, handling of the polishing layer 31 having the adhesive layer 33 provided thereon is facilitated. In addition, a contamination of the adhesive layer 33 is avoided.
Therefore, the polishing pad 30 containing no defect in the adhesive layer 33 can be easily manufactured.
Japanese Patent Laid-Open No. 2001-219,362 discloses a structure of a polishing pad 50 having a single layer structure and a technique for joining the polishing pad 50 to a platen 41, as shown in FIG. 3B. The polishing pad 50 includes a plurality of through holes 51 formed to extend from a front surface to a back surface thereof.
More specifically, in the polishing pad 50, an adhesive layer 52 is provided on the back surface only in a position where no through hole 51 is formed. Such polishing pad 50, in turn, is joined to the platen 41 by the adhesive layer 52.
However, this is the technique for joining the polishing pad 50 of the single layer structure to the platen 41, and it is difficult to simply apply such technique for the single layer structure to the technique for joining the polishing layer 31 of the polishing pad 30 having the multiple-layered structure to support plate 32.
Japanese Patent Laid-Open No. 2001-219,362 also discloses that the adhesive layer 52 is formed by employing an adhesive agent or a two-sided tape. When the adhesive layer 52 is formed by employing an adhesive agent, through holes 51 are formed in the polishing pad 50 coated with an adhesive agent over the back surface thereof.
However, this leads to handling the polishing pad 50 under the condition, in which the adhesive agent coated thereon is exposed, and thus the handling thereof is difficult and a contamination may be possibly caused in the adhesive agent.
It is not intended that the present invention is limited to the configurations illustrated in the above-described embodiment, and various modifications thereof are available. For example, while it is assumed that the through holes 34 of the polishing layer 31 are circular small holes in the above-described configuration, such through holes 34 may alternatively be formed to have variety of geometries (not shown) such as cross-shaped heteromorphy holes, linear concave trenches and the like.
Further, the configuration of simultaneously providing the adhesive layer 33 and the stripping form 36 on the polishing layer 31 by pasting the adhesive layer 33 of the two-sided tape, in which only one stripping form in one side is stripped, on the polishing layer 31 is illustrated in the above-described configuration.
Alternatively to above, after the adhesive agent is applied on the back surface of the polishing layer 31 to form the adhesive layer 33, the stripping form 36 may be pasted thereon. In this case, though the adhesive layer 33 is formed of an adhesive agent, easier handling of polishing layer 31 is provided and a contamination in the adhesive agent is avoided.
It is apparent that the present invention is not limited to the above embodiment, and may be modified and changed without departing from the scope and spirit of the invention.

Claims

1. A polishing pad having a multiple-layered structure and being utilized in a chemical mechanical polishing (CMP) process, comprising:

a disc-shaped polishing layer having a plurality of through holes formed to extend from a front surface to a back surface thereof;

an adhesive layer provided only in a position in a back surface of said polishing layer where said through hole is not formed; and

a disc-shaped support plate having a flat surface, which is joined to said back surface of the polishing layer by said adhesive layer.

2. The polishing pad according to claim 1, wherein a surface of said support plate is exposed in a bottom of said through hole in said polishing layer without disposing said adhesive layer thereon.

3. A chemical mechanical polishing (CMP) apparatus for performing a CMP process for a workpiece with a polishing pad, comprising:

the polishing pad as set forth in claim 1;

a disc-shaped platen having a front surface, which is joined to a back surface of said polishing pad;

a pad actuating unit for actuating a rotation of said platen that is provided with said polishing pad;

a slurry supplying unit for supplying a slurry to said polishing pad that is actuated to be rotated; and

a workpiece pressing unit for supporting said workpiece and pressing said workpiece to said polishing pad that is actuated to be rotated.

4. A chemical mechanical polishing (CMP) apparatus for performing a CMP process for a workpiece with a polishing pad, comprising:

the polishing pad as set forth in claim 2;

5. A method for manufacturing a polishing pad, which has a multiple-layered structure and is utilized in a chemical mechanical polishing (CMP) process, including:

providing an adhesive layer and a stripping form on a back surface of a disc-shaped polishing layer having a front surface serving as a polishing surface;

forming a plurality of through holes, which extend from a surface of said polishing layer through said adhesive layer to a back surface of said stripping form;

stripping said stripping form from the back surface of said polishing layer having said plurality of through holes formed therein; and

joining the back surface of said polishing layer exposed by stripping said stripping form to a surface of a support plate by said adhesive layer.

6. The method for manufacturing the polishing pad according to claim 5, further comprising

preparing a two-sided tape having a structure including an adhesive layer and stripping forms affixed to both sides of the adhesive layer,

wherein said providing the adhesive layer and the stripping form on the back surface of the disc-shaped polishing layer includes providing an exposed adhesive layer of said two-sided tape onto a back surface of the polishing layer, said exposed adhesive layer of the two-sided tape being exposed by stripping only said stripping form disposed on the front surface of said two-sided tape.

7. The method for manufacturing the polishing pad according to claim 5, wherein said providing the adhesive layer and the stripping form on the back surface of the disc-shaped polishing layer includes pasting said stripping form after said adhesive layer is provided with the back surface of said polishing layer by an application of an adhesive agent.