JPH09174417A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high flatness and high parallelism by providing multiple holes penetrating the surface and back face on the pressure ring of a polishing head supporting a mount plate stuck with a polished member on a polishing surface plate via the pressure ring. SOLUTION: A pressure ring 10 is a doughnut plate made of an elastic body, it is with multiple holes 20, and it is uniformly bent when it is compressed between a mount plate 6 and a polishing head 4. The pressure ring portions between the holes 20 of the pressure ring 10 can be protruded and deformed to the holes 20 when the pressure ring 10 is pinched and compressed between the mount plate 6 and the polishing head 4. If the surface of the polishing head 4 is undulated or warped, the load applied to the polishing head 4 is not transmitted to the mount plate 6 when the protruded portions face the holes 20, pressure is uniformly distributed and transmitted to various sections of the pressure ring 10 by the mount plate 6, and the pressure ring 10 is kept at the flat state.

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 example, a technology effectively applied to mirror polishing of a semiconductor thin plate (semiconductor wafer) used for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art A semiconductor wafer used for manufacturing a semiconductor device such as an IC (Integrated Circuit Device) has high flatness and parallelism in order to perform fine processing with high yield in pattern formation by photolithography. Is required.

In order to obtain a wafer with high flatness and high parallelism,
The surface of the wafer is finished by mirror polishing. The mirror polishing of the wafer is performed by a polishing device (polishing device).

Regarding the polishing apparatus, for example, "Monthly Semiconductor World" published by Press Journal Co., Ltd. March 1983 issue, February the same year
Issued on the 15th, it is described in P59-P83.

In the reference, a wafer (semiconductor wafer) is attached to the lower surface of a mount plate fixed to the lower surface of the head with wax, the head is pressed downward, and the wafer is used as a polishing cloth on the upper surface of a surface plate. A schematic view of a single-sided polishing apparatus for polishing while pressing is described.

In addition, a polishing machine "50" manufactured by Speedfam
"SPAW" has a structure in which a pressure ring is provided between the head and the mount plate.

[0007]

The conventional polishing apparatus generally has a structure as shown in FIG. That is,
A circular polishing platen 2 is fixed to the upper end of a rotating shaft 1 rotated by a motor (not shown). A polishing cloth 3 is attached to the upper surface of the polishing platen 2.

A polishing head 4 made of a stainless disc or the like is arranged above the polishing platen 2. The polishing head 4 is supported by a rod 5. This rod 5
Is a piston rod of a cylinder fixed to the top end of an unillustrated column (housing) of the polishing apparatus. Although one or more cylinders are provided, FIG. 5 shows an example in which four cylinders are provided in the upper part of the column. In a projected state, each of the cylinders is arranged on a predetermined circumference that is concentric with the polishing platen.

Around the polishing head 4, a fixture 7 for fixing the mount plate 6 made of ceramics or the like is attached.

The mount plate 6 is made of a disk having substantially the same size as the polishing head 4, and a plurality of semiconductor wafers 9 are attached to one surface thereof with wax or the like. The mount plate 6 is attached so as to overlap the polishing head 4, and at this time, a donut-shaped pressure ring 10 is interposed therebetween.

In such a structure, after mounting the mount plate 6 to which the semiconductor wafer 9 is attached to the polishing head 4, a slurry-like polishing liquid is supplied onto the polishing cloth 3 and the polishing platen 2 is rotated. Further, the rod 5 is advanced toward the polishing platen 2 to press the semiconductor wafer 9 against the polishing cloth 3 to perform mirror polishing.

However, the present inventor has clarified that the conventional polishing apparatus of this type has the following problems.

At the time of polishing, as shown in FIG. 6, a polishing head 4 made of stainless steel by a rod 5 of an air cylinder.
A load is applied to the central part of the. Since the polishing head 4 made of stainless steel is not always flat and has a wavy surface, an uneven pressure distribution is generated on the wafer when pressed. Then, in some cases, the center portion of the mount plate 6 is deformed so as to bulge upward, and the semiconductor wafer 9 is polished such that the center side of the polishing head 4 is thicker and the thickness becomes thinner toward the outer periphery of the polishing head 4. However, the flatness of the semiconductor wafer 9 and the parallelism of the front and back surfaces deteriorate.

The polishing head 4 has, for example, a diameter of 50.
In the case of a stainless material of about 0 mm, the thickness is about 50 mm. The center of the polishing head is 200 kg
A load as high as is applied.

Deterioration of flatness due to the above phenomenon has become a more important problem in today's world where the diameter and height of the wafer are increasing.

According to the analysis and examination by the present inventor, the mount plate 6 for transmitting the pressure from the polishing head 4 to the mount plate 6 is caused by the presence of undulations, warps (curves), etc. on the surface of the polishing head 4. Load from the mount plate 6
It was found that the pressure was not evenly transmitted to the.

An object of the present invention is to provide a polishing apparatus capable of obtaining high flatness and high parallelism.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0019]

The following is a brief description of an outline of typical inventions disclosed in the present application.

(1) A rotation-controlled polishing platen having a polishing cloth attached on its upper surface, and a polishing head for supporting a mount plate having a member to be polished attached to the polishing platen with a pressure ring interposed therebetween. And a structure in which the pressure ring has a plurality of holes penetrating through the front and back surfaces. An auxiliary pressure mechanism for pressing the mount plate against the polishing cloth is provided in the polishing head portion inside the pressure ring. The auxiliary pressurizing mechanism includes an elastic bag body that contacts the mount plate surface and a high-pressure air supply mechanism that supplies and exhausts compressed air to the bag body. The plurality of holes provided in the pressure ring are arranged so that the mount plate is flat during polishing.

According to the above-mentioned means (1), since (a) the mount plate for transmitting pressure from the polishing head to the mount plate is provided with a plurality of holes, the surface of the polishing head is undulated or warped. When the protruding portion due to (curving) faces the hole, it does not transmit the load of the polishing head to the mount plate. Further, when the protruding portion comes into contact with the mount plate portion having a small area between the holes, the mount plate portion between the holes has holes on both sides, and thus has a structure that is easily deformed. In order to appropriately deform and reduce an excessive load, each part of the pressure ring uniformly distributes and transmits the pressure to the mount plate. As a result, the mount plate that supports the wafer is polished while being kept flat, so that the wafer is polished flat and the front and back surfaces are parallel. Particularly, since the holes are dispersed and arranged so that the mount plate is kept flat during polishing, the wafer can be surely flattened and parallelized.

(B) In the polishing head portion inside the pressure ring, compressed air is supplied to an elastic bag to apply pressure from the central portion of the mount plate to the peripheral portion of the mount plate to mount it. Since the mount plate has an auxiliary pressure mechanism that uniformly presses the entire plate against the polishing platen, the mount plate is polished in a state parallel to the polishing platen, thus flattening and parallelizing the wafer. Can be achieved.

(C) The uniform transmission of the load from the polishing head to the mount plate due to the presence of the plurality of holes provided in the pressure ring according to (a) above, and the mounting plate by the auxiliary pressure mechanism according to (b) above. The flattening and parallelization of the wafer can be achieved by polishing with a uniform pressing action on the polishing platen.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for describing the embodiments of the present invention, components having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

1 to 4 are views relating to a polishing apparatus according to an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view showing a main part of the polishing apparatus, and FIG. 2 is attached to a polishing head. FIG. 3 is a schematic view showing the elastic sheet, FIG. 3 is a schematic perspective view showing the appearance of the polishing apparatus, and FIG. 4 is a schematic cross-sectional view of a main part showing a polishing state.

In the polishing apparatus of this embodiment, as shown in FIG. 3, the polishing platen 2 is arranged at the center of the upper surface of the machine base 15. The rotation of the polishing platen 2 is controlled by a motor (not shown) provided in the machine base 15. A polishing cloth 3 is attached to the flat upper surface of the polishing platen 2.

Further, four air cylinders 19 are arranged in the projecting portion 17 at the upper part of the column (housing) 16 extending upward from the back side of the machine base 15. The four air cylinders 19 are arranged along the concentric circles of the polishing platen 2. The air cylinder 19 faces downward, and the rod (piston rod) 5 is projected from the lower end.
The polishing head 4 made of a disk is fixed to the tip of the rod 5.

A mount plate 6 to which a semiconductor wafer 9 is attached on the lower surface is attached to the polishing head 4. The wafers 9 are attached to the lower surface of the mount plate 6 side by side along the circumference. Each wafer 9 attached to the four mount plates 6 faces the polishing cloth 3 attached to the polishing platen 2. The polishing head 4
Is a stainless plate having a thickness of 50 mm and a diameter of 500 mm, for example.

A fixture 7 is attached around the polishing head 4 as shown in FIG. This fixture 7
Fixes the mount plate 6 having substantially the same size as the polishing head 4 in a fitted state.

The mount plate 6 is made of a ceramic disk, and a plurality of semiconductor wafers 9 are attached to one surface (lower surface) thereof with wax or the like. The mount plate 6 is attached so as to overlap the polishing head 4, and at this time, a donut-shaped pressure ring 10 is interposed therebetween.

A semiconductor wafer 9 is attached to one surface (lower surface) of the mount plate 6 with an adhesive such as wax (not shown).

From the overhanging portion 17 of the column 16,
The supply pipe 22 is suspended. The slurry-like polishing liquid is supplied onto the polishing cloth 3 from the supply pipe 22.

In the polishing apparatus of this embodiment, the polishing platen 2 is rotated while the slurry-like polishing liquid is supplied onto the polishing cloth 3, and the air cylinder 19 is operated to move the rod 5 as shown in FIG. To lower the semiconductor wafer 9 to the polishing cloth 3
And the lower surface of the semiconductor wafer 9 is polished.

On the other hand, in this embodiment, the pressure ring 1 is used.
Reference numeral 0 is an elastic donut plate such as a resin elastic sheet, and a plurality of holes 20 are provided as shown in FIG. The plurality of holes 20 are arranged so as to uniformly bend when compressed between the mount plate 6 and the polishing head 4. That is, the pressure ring portion between the holes 20 of the pressure ring 10 can be protruded and deformed toward the hole 20 side when being compressed by being sandwiched between the mount plate 6 and the polishing head 4.

Therefore, when the surface of the polishing head 4 is wavy or warped, the protruding portion due to waviness or warp (curvature) faces the hole 20 and the polishing head 4
The load applied to the mount plate 6 will not be transmitted to the mount plate 6. In addition, when the protruding portion comes into contact with the mount plate portion having a small area between the holes 20, the holes 2
The mounting plate portion between 0 and hole 20 has holes 2 on both sides.
Since there is 0 and the structure can be deformed, the pressure ring 10 is deformed appropriately to reduce an excessive load, so that each part of the pressure ring 10 uniformly disperses and transmits the pressure to the mount plate 6. As a result, the mount plate 6 that supports the wafer 9
Since the polishing is performed while maintaining a flat state, the wafer 9 is polished flat and the front and back surfaces are parallel to each other.

On the other hand, since the conventional pressure ring is a donut plate having no holes, even if it is compressed between the mount plate and the polishing head, the compression force of each internal portion of the pressure ring is increased. On the other hand, it cannot be deformed enough,
The mount plate has large undulations or warpage, the wafer supported by the pressure ring is inclined with respect to the flat surface of the polishing platen, and uneven polishing of the wafer surface is caused, causing flatness / parallelization failure.

In the present embodiment, as shown in FIG. 2, the holes 20 are large on the outside so that the pressure ring 10 can be deformed to have a uniform thickness over the entire area. The pressure ring may be uniformly deformed by changing the arrangement density of the holes. Further, the holes are not limited to circular holes, and holes of any shape are effective.

On the other hand, in the present embodiment, as shown in FIG. 1, the auxiliary pressing mechanism 25 for pressing the mount plate 6 against the polishing cloth 3 in the polishing head portion inside the pressing ring 10.
Is provided. The auxiliary pressurizing mechanism 25 includes a bag body 26 made of elastic rubber that contacts the upper surface of the mount plate 6, and a high-pressure air supply mechanism 27 that supplies and exhausts compressed air to the bag body 26. Has become.

The high-pressure air supply mechanism 27 has a guide hole 28 provided in the rod 5, and a supply / exhaust mechanism (not shown) for sending compressed air into the guide hole 28 or discharging compressed air to the outside from the guide hole 28. It consists of One end of the guide hole 28 is exposed on the lower surface of the polishing head 4 and faces the inside of the bag body 26.

Therefore, the compressed air is sent into the bag body 26 by the high pressure air supply mechanism 27, so that the bag body 26 is inflated. Since the bag body 26 gradually expands the contact area from the center of the mount plate 6 to the periphery, the mount plate 6 faces the polishing surface plate 2 while maintaining the state parallel to the flat surface of the polishing surface plate 2. Be pressed against. As a result, the entire lower surface of the semiconductor wafer 9 adhered to the lower surface of the mount plate 6 is evenly pressed against the polishing cloth 3 attached to the polishing platen 2, and uniform polishing is possible.

A guide hole 28 is provided by the high pressure air supply mechanism 27.
When the compressed air is removed from the inside, the bag body 26 is deflated and the action of pressing the mount plate 6 against the polishing platen 2 is released.

In such a structure, after mounting the mount plate 6 to which the semiconductor wafer 9 is attached to the polishing head 4, the slurry polishing liquid is supplied onto the polishing cloth 3 and the polishing platen 2 is rotated. In addition, the rod 5 is advanced toward the polishing platen 2 to press the semiconductor wafer 9 against the polishing cloth 3 to perform mirror polishing, but a plurality of pressure rings 10 for transmitting the load from the polishing head 4 to the mount plate 6 are provided. And has a hole 20 in which the whole is uniformly deformed,
Since the mount plate 6 is uniformly pressed against the polishing cloth 3 of the polishing platen 2 by the auxiliary pressure mechanism 25, the mount plate 6 is always flat and parallel to the flat surface of the polishing platen 2 for polishing. Be seen. Therefore, the wafer 9
The polishing surface is also pressed against the polishing cloth 3 to be polished, and the flatness of the surface of the polished wafer 9 and the parallelism of the front and back surfaces are increased.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

In the above description, the case where the invention made by the present inventor is mainly applied to the polishing technique of a semiconductor wafer used for manufacturing a semiconductor device, which is the field of application of the background, has been described, but the invention is not limited to this. Instead, it can be applied to, for example, a polishing technique for magnetic disks, liquid crystal glass, solar cell substrates, and the like.

The present invention can be applied at least to the technique of polishing a plate material.

[0046]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

(1) According to the polishing apparatus of the present invention, even if the flatness of the polishing head is poor, the pressure distribution applied to the semiconductor wafer can be made uniform by providing the pressure ring with a plurality of holes. , Even if the polishing head is curved,
Since the entire surface of the semiconductor wafer can be pressed against the polishing cloth by uniformly pressing down the mount plate of the rubber bag body by the auxiliary pressure mechanism, it is possible to perform wafer polishing with high flatness and high parallelism.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a main part of a polishing apparatus that is an embodiment of the present invention.

FIG. 2 is a schematic view showing an elastic sheet attached to a polishing head in the polishing apparatus of the present embodiment.

FIG. 3 is a schematic perspective view showing the external appearance of the polishing apparatus of this embodiment.

FIG. 4 is a schematic cross-sectional view of a main part showing a polishing state in the polishing apparatus of this embodiment.

FIG. 5 is a schematic cross-sectional view showing a main part of a conventional polishing apparatus.

FIG. 6 is a schematic sectional view showing a defective polishing state in a conventional polishing apparatus.

[Explanation of symbols]

1 ... Rotation axis, 2 ... Polishing surface plate, 3 ... Polishing cloth, 4 ... Polishing head, 5 ... Rod, 6 ... Mount plate, 7 ... Fixing tool,
9 ... Semiconductor wafer, 10 ... Pressure ring, 15 ... Machine stand, 1
6 ... Column (housing), 17 ... Overhanging portion, 19 ... Air cylinder, 20 ... Hole, 22 ... Supply pipe, 25 ... Auxiliary pressurizing mechanism,
26 ... Bag body, 27 ... High-pressure air supply mechanism, 28 ... Guide hole.

Claims (5)

[Claims] 1. A rotation control polishing platen having a polishing cloth attached to the upper surface thereof, and a polishing head supporting a mount plate having a member to be polished attached to the polishing platen with a pressure ring interposed therebetween. A polishing apparatus having the above-mentioned, wherein the pressure ring has a structure in which a plurality of holes penetrating through the front and back surfaces are provided. 2. A rotation-controlled polishing platen having a polishing cloth attached to the upper surface thereof, and a polishing head supporting a mount plate having a member to be polished attached to the polishing platen with a pressure ring interposed therebetween. A polishing apparatus having the above, wherein an auxiliary pressure mechanism for pressing a mount plate against a polishing cloth is provided in a polishing head portion inside the pressure ring. 3. The auxiliary pressurizing mechanism includes an elastic bag body that contacts the mount plate surface, and a high-pressure air supply mechanism that supplies and exhausts compressed air to and from the bag body. The polishing apparatus according to claim 2. 4. The polishing apparatus according to claim 2, wherein the pressure ring has a structure having a plurality of holes penetrating the front and back surfaces. 5. The plurality of holes provided in the pressure ring are arranged so that the mount plate is flat during polishing. Polishing equipment.