JP2000190203A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing device which can maintain the flatness without making the surface form in a convex form, as well as can improve the surface coarseness by the polishing. SOLUTION: A carrier 4 has a carrier main body 7 having a housing recess 6 whose lower side is opened; an elastic membrane 9 provided to form a pressurizing chamber 8 to the housing recess 6; a pressure transmitting medium 10 provided at the opposite side of the pressurizing chamber 8 making the elastic membrane 9 at the center; and a retainer 11 provided at the periphery of the pressure transmitting medium 10 and holding a work W. And the pressure transmitting medium 10 has a divergent form to expand its cross section gradually, and its bottom surface part 10d has a plane form in order to press the work W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing a surface of a semiconductor wafer or the like, and more particularly to a polishing apparatus for polishing a semiconductor wafer flat.

[0002]

2. Description of the Related Art To manufacture a semiconductor wafer, a single crystal semiconductor ingot is made from polycrystalline silicon by, for example, the Czochralski method, and the ingot is sliced to a predetermined thickness by a multi-wire saw or the like to manufacture a semiconductor wafer. I do.

In order to flatten the surface of the semiconductor wafer, polishing is performed by a polishing apparatus.

A conventional polishing apparatus is disclosed in Japanese Patent Application Laid-Open No. 63-5 / 1988.
As described in Japanese Patent Publication No. 2967, a storage recess is formed below the carrier body, and an elastic film for closing a lower end opening edge is provided below the storage recess. The pressurized chamber formed by the partitioning is filled with a fluid, and a flat disc shape is brought into contact with the elastic film to provide a pressure transmitting medium (mount plate), and the work is uniformly pressed by the pressure transmitting medium. There is a polishing apparatus that has been developed.

[0005] As shown in FIG. 5, the carrier 31 is a carrier main body 3 having a storage recess 32 whose lower part is opened.
3, an elastic film 35 provided so that the pressurizing chamber 34 is formed in the accommodation recess 32, and a flat disk-shaped pressure transmission provided on the opposite side of the elastic film 35 from the pressurizing chamber 34. A medium 36, a retainer 37 provided around the pressure transmitting medium 36 to hold the work W, and a squeegee 40 surrounding the retainer 37, are provided by the pressure transmitting medium 36 via the back film 39. The surface plate 3 evenly
There is a polishing apparatus that presses against the polishing cloth P provided on the polishing pad 8.

[0006]

Since all of these conventional polishing apparatuses press the work uniformly with a flat disk-shaped pressure transmitting medium, for example, in the conventional example shown in FIG. When the relative velocity vector of the in-plane portion of W with respect to the polishing cloth P is integrated over time, the value takes the minimum value at the center of the work W and takes the maximum value at the outer peripheral portion. The polished workpiece also has a convex shape in which the shape after processing is thickest at the center portion and becomes thinner toward the outer peripheral portion.

The reason why the convex shape is formed is that the polishing rate of the workpiece is a time function such as the relative speed with respect to the polishing cloth, the pressure, the temperature, and the like. That is, when the pressure distribution is uniform, the polishing rate changes according to the relative speed of each part.

[0008] Therefore, conventionally, when single-side polishing is performed, the surface shape of the work becomes a convex shape, and the flatness is substantially reduced.

The present invention has been made in view of the above circumstances, and has as its object to provide a polishing apparatus which can improve the surface roughness by polishing and maintain the flatness without changing the surface shape into a convex shape. And

[0010]

Means for Solving the Problems In order to achieve the above object, the invention of claim 1 of the present application comprises a platen provided with a polishing cloth, and a work to be polished by being pressed by the polishing cloth. In a polishing apparatus having a carrier rotated by a rotating shaft, the carrier has a carrier main body having a storage recess opened at the bottom, an elastic film provided so as to form a pressure chamber in the storage recess, and It has a pressure transmitting medium provided on the opposite side to the pressurizing chamber with the elastic film interposed therebetween, and a retainer provided around the pressure transmitting medium and holding the work, and the pressure transmitting medium has a cross-sectional area which is sequentially enlarged. The gist of the present invention is to provide a polishing apparatus characterized in that the polishing apparatus has a divergent shape and a bottom surface has a planar shape for pressing a work.

According to the second aspect of the present invention, the polishing apparatus according to the first aspect, wherein the pressure transmitting medium is a cone having a flat cylindrical portion having a flat bottom surface. And

The polishing apparatus according to claim 2, wherein the conical body of the pressure transmitting medium is flat and the top is truncated into a spherical shape or a planar shape. The gist is that

[0013] In the invention of claim 4 of the present application, the gist is the polishing apparatus according to any one of claims 1 to 3, wherein the pressure transmission medium is alumina-based fine ceramics. .

The polishing method according to any one of claims 1 to 4, wherein the pressure transmitting medium has a laminated structure of a thin body having a thickness of 3 to 5 mm. The gist is that it is a device.

According to a sixth aspect of the present invention, there is provided a polishing apparatus according to the fifth aspect, wherein the thin body is a molded body of alumina-based fine ceramics.

According to a seventh aspect of the present invention, in the polishing apparatus according to the fifth or sixth aspect, the pressure transmitting medium is formed by laminating a thin body with an adhesive. And

In the polishing apparatus according to the present invention, preferably, the pressure transmitting medium has a laminated structure in which a thin body is fixed with screws or pins. It is a gist.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a polishing apparatus according to the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 2, a polishing apparatus 1 according to the present invention comprises: a platen 2 provided with a polishing cloth P;
It has a carrier 4 on which a work W to be pressed and polished against a polishing cloth P is mounted and rotated by a rotating shaft 3, and a slurry pipe 5 for supplying a slurry S.

As shown in FIG. 1, the carrier 4 has a flat disk shape and is provided so as to form a carrier body 7 having a storage recess 6 opened downward and a pressurizing chamber 8 formed in the storage recess 6. An elastic film 9, a pressure transmitting medium 10 provided on the opposite side to the pressurizing chamber 8 with the elastic film 9 interposed therebetween, a retainer 11 provided around the pressure transmitting medium 10 for holding the work W, A ring-shaped squeegee 12 provided around the transmission medium 10 and the retainer 11 and made of an elastic body.
And a back film 13 interposed between the pressure transmission medium 10 and the work W.

The elastic film 9 is made of, for example, a stainless disk reinforced silicon rubber in the shape of a thin disk, and has a retainer 11.
Is made of PTFE (Polytetrafluoroethylene), has a strip shape having an arc surface, and is arranged in a plurality of ring shapes.

As shown in FIG. 3, the pressure transmitting medium 10 has a divergent shape in which the cross-sectional area gradually increases, and the bottom surface portion 10d has a planar shape for pressing the work W. For example, the silicon wafer W has a diameter of For 300mm, the diameter D
300.8 mm, the top portion 10a has a spherical shape, the center portion has a thickness T25mm, the outer peripheral end portion has a thickness t10mm, and the lower portion has a truncated cone 10c having a flat cylindrical portion 10b. The silicon wafer W is pressed via the back film 13 at the bottom surface portion 10d of the planar shape 10b.

The top portion 10a of the pressure transmitting medium 10 may not necessarily be truncated to a spherical shape but to a planar shape, and need not necessarily be truncated to a spherical shape or a planar shape. Although the object of the present invention can be achieved, it is preferable to cut off to a spherical shape or a planar shape in consideration of the adjustment of the pressure applied to the silicon wafer W and the durability of the elastic film 9.

The squeegee 12 is made of, for example, silicone rubber, and the back film 13 is made of, for example, foamed polyurethane.

The pressurizing chamber 8 is connected to a pressurizing device (not shown) through an air supply passage 14 provided on the rotating shaft 3 so that the pressurizing chamber 8 is appropriately pressurized.

Next, a polishing process of the silicon wafer W using the polishing apparatus 1 having the pressure transmitting medium 10 according to the present invention will be described.

As shown in FIG. 1, a silicon wafer W to be polished is held by a retainer 11 and attached to a carrier 4. The silicon wafer W attached to the carrier 4 is in close contact with the planar bottom portion 10 d via the back film 13.

Thereafter, while supplying the slurry S to the polishing pad P from the slurry pipe 5 shown in FIG. 2, the carrier 4 rotating clockwise is lowered, and the polishing pad provided on the rotary platen 2 is rotated clockwise. The silicon wafer W is pressed against P. While pressing the silicon wafer W against the rotating polishing cloth P,
By rotating the rotating carrier 4 in the X-axis and Y-axis directions, the silicon wafer W is uniformly polished by two-dimensional complicated movement. In this polishing step, the pressurizing chamber 8 of the carrier body 7 is pressurized by compressed air from a pressurizing device via an air supply path 14 provided on the rotating shaft 3, and the pressure transmitting medium 10 is Is pressed downward through At this time, since the pressure transmitting medium 10 has the shape of a truncated cone 10c having a flat cylindrical portion 10b at the lower portion, the pressing force applied to the silicon wafer W is large at the central portion and the pressure transmitting medium 10 is bent. The outer peripheral portion becomes smaller. Accordingly, the polishing rate by the pressing force becomes maximum at the central portion, decreases toward the outer periphery, and becomes minimum at the outer peripheral portion. On the other hand, the polishing speed based on the relative speed with respect to the polishing pad P is, on the contrary, minimum at the central portion and maximum at the outer peripheral portion. Of the wafer W is uniformly polished, and the entire wafer W is also uniformly polished.

As described above, by designing the shape of the pressure transmitting medium 10 so as to offset the increase / decrease in the polishing rate due to the relative speed, and adjusting the increase / decrease in the polishing rate due to the pressure, a silicon wafer W having excellent flatness can be obtained. You can always get.

Further, since the pressure transmitting medium 10 has a divergent and thin-walled cross section, the pressure transmitting medium 10 has elasticity and easily absorbs vibration, so that the polished surface is not affected by the vibration. A highly accurate polished surface can be obtained.

Further, for example, the pressure transmitting medium 1 is applied so that a larger pressing force is applied to the central portion of the silicon wafer W.
If 0 is designed, a silicon wafer having an overall concave shape can be obtained.

Since the flat cylindrical portion 10b is provided below the pressure transmitting medium 10, the tip portion is not chipped at the time of manufacturing the pressure transmitting medium 10, and the pressure transmitting medium 10 is not damaged by concentrated stress during use.

In the above embodiment, the pressurized medium is described as air, but an inert gas such as nitrogen or water,
It is also possible to use liquids such as oil.

Next, another embodiment of the polishing apparatus according to the present invention will be described.

The first embodiment will be described by giving the same reference numerals to the same parts. As shown in FIG. 4, the carrier 4 has a flat disk shape, a carrier body 7 having a storage recess 6 opened at the bottom, and an elastic film 9 provided to form a pressurizing chamber 8 in the storage recess 6. A pressure transmission medium 20 provided on the opposite side of the pressure chamber 8 with the elastic film 9 interposed therebetween; and a retainer 1 provided around the pressure transmission medium 20 for holding the workpiece W.
1, a pressure transmission medium 20, an elastic ring-shaped squeegee 12 provided so as to surround the pressure transmission medium 20 and the retainer 11, and a back film 13 interposed between the pressure transmission medium 20 and the work W. Have.

The pressure transmitting medium 20 has a spherical top 20a.
And a truncated cone 20c having a flat cylindrical portion 20b at the bottom
The bottom surface 20d of the cylindrical portion 20b has a planar shape. Furthermore, since the pressure transmission medium 20 has a central portion thickness of 25 mm and a divergent shape with a diameter of 300.8 mm, the pressure transmission medium 20 has a thickness of 3 to 3 mm to resemble the shape.
It is formed in a laminated structure of a thin body of 5 mm, and this laminated structure is formed by bonding the molded body 20p of alumina-based fine ceramics with a bonding means, for example, an adhesive.

Since the pressure transmitting medium 20 having such a structure has a leaf spring structure, the central portion of the workpiece W can be more effectively pressed with a large pressing force and the outer peripheral portion thereof can be pressed more effectively with a small pressing force. The work W can be polished.

In this embodiment, an adhesive is used for the connecting means. However, for example, a pressure transmitting medium 20 having a leaf spring structure can be obtained by using a screw or a pin. In this case, the work W can be more uniformly polished.

[0039]

EXAMPLE A pressure transmission medium made of alumina ceramics having a diameter of 300.8 mm, a spherical top, a center thickness of 25 mm, and an outer end thickness of 10 mm was used.
When a silicon wafer having a thickness of 00 mm and a thickness of 750 mm was polished using a suspension of pure water of colloidal silica, a silicon wafer having a concave shape in which the thickness of a central portion was 1 μm thinner than that of an outer peripheral portion was obtained.

[0040]

By using the polishing apparatus according to the present invention, a highly accurate polished surface can be obtained, and a flat work can be obtained without making the surface shape convex.

If a flat cylindrical portion is provided in the pressure transmitting medium,
The tip portion is not chipped during the production of the pressure transmission medium, and the pressure transmission medium is not damaged by concentrated stress during use.

If the conical body of the pressure transmitting medium is flattened and the top is truncated to a spherical body or a planar shape, the pressure applied to the work can be easily adjusted, and a highly accurate polished surface can be obtained. The durability of the elastic film can be improved.

If the pressure transmission medium is made of alumina fine ceramics, the medium is durable and does not contaminate the work.

If the pressure transmitting medium has a laminated structure of a thin body having a thickness of 3 to 5 mm, it becomes a leaf spring structure, and the central part of the work is more effectively pressed with a large pressing force, and the outer peripheral part thereof is more effectively pressed with a small pressing force. The work can be pressed, and the work can be polished more uniformly.

If the thin body is formed from a molded body of alumina fine ceramics, a pressure transmitting medium having a leaf spring structure which is durable and does not contaminate the work can be obtained.

If the pressure transmitting medium has a laminated structure in which a thin body is bonded with an adhesive, a pressure transmitting medium having a leaf spring structure can be easily obtained.

If the pressure transmitting medium has a laminated structure in which a thin body is fixed with screws or pins, a stronger pressure transmitting medium having a leaf spring structure can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a carrier used in a polishing apparatus according to the present invention.

FIG. 2 is an explanatory view of a polishing apparatus according to the present invention.

FIG. 3 is a side view of a pressure transmission medium used for a carrier of the polishing apparatus according to the present invention.

FIG. 4 is a sectional view of another embodiment of the carrier used in the polishing apparatus according to the present invention.

FIG. 5 is a cross-sectional view of a carrier used in a conventional polishing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polishing apparatus 2 Surface plate 3 Rotating shaft 4 Carrier 5 Slurry pipe 6 Storage concave part 7 Carrier main body 8 Pressurizing chamber 9 Elastic film 10 Pressure transmission medium 10a Top part 10b Column part 10c Truncated cone 10d Bottom part 11 Retainer 12 Squeegee 13 Back Film 14 Airway

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[Procedure amendment]

[Submission date] March 10, 1999 (1999.3.1.
0)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 5

[Correction method] Change

[Correction contents]

FIG. 5

Claims (8)

[Claims] 1. A polishing apparatus comprising: a platen provided with a polishing cloth; and a carrier on which a work to be pressed and polished by the polishing cloth is mounted and which is rotated by a rotating shaft. A carrier body having a storage recess, an elastic film provided so as to form a pressure chamber in the storage recess, a pressure transmission medium provided on the opposite side of the pressure chamber with the elastic film interposed therebetween, A retainer provided around the pressure transmission medium for holding the work, wherein the pressure transmission medium has a divergent shape whose cross-sectional area gradually increases, and a bottom surface has a planar shape for pressing the work. Polishing equipment. 2. The polishing apparatus according to claim 1, wherein the pressure transmitting medium is a conical body having a flat cylindrical portion whose bottom surface has a planar shape. 3. The polishing apparatus according to claim 2, wherein the cone of the pressure transmitting medium is flat, and the top is truncated to a spherical shape or a planar shape. 4. The polishing apparatus according to claim 1, wherein the pressure transmitting medium is alumina-based fine ceramics. 5. The polishing apparatus according to claim 1, wherein the pressure transmitting medium has a laminated structure of a thin body having a thickness of 3 to 5 mm. 6. The polishing apparatus according to claim 5, wherein the thin body is a molded body of alumina fine ceramics. 7. The polishing apparatus according to claim 5, wherein the pressure transmitting medium has a laminated structure by bonding a thin body with an adhesive. 8. The polishing apparatus according to claim 5, wherein the pressure transmitting medium has a laminated structure in which a thin body is fixed with screws or pins.