JP2001198809A - Polishing work holding board, polishing device and work polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing work holding board, a polishing device and a work polishing method capable of obtaining a work having excellent flatness and a demon mirror image without injuring and contaminating the back of the work, when holding the work by vacuum suction. SOLUTION: In a polishing work holding board 1 equipped with a work holding board body 2 having many through holes 4 to hold the work by vacuum suction, the work holding surface 8 of the holding board body 2 is covered by a material 3 having hardness equal to or less than the hardness of the work, and plural pins 9 having tip surfaces as sucking positions or beams are formed on the surface of the material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing work holding plate, a polishing apparatus, and a work polishing method used when precision polishing the surface of a work such as a semiconductor wafer.

[0002]

2. Description of the Related Art Conventionally, in a polishing process, a plate made of a rigid material such as glass, metal, or ceramic is used as a work holding plate, and a work is attached to the surface of the work holding plate with an adhesive such as wax or a porous material having air permeability. 2. Description of the Related Art There is a method of holding a work by vacuum suction or the like on a work holding plate provided with a plurality of through-holes in the surface of a work material.

However, when a work is directly held on the surface of a work holding plate made of metal, ceramics, or the like, dirt is generated on the back surface of the work, and scratches occur when the holding plate is harder than the work. Therefore, for the purpose of preventing scratches and dirt on the back surface of the work and obtaining a work with good flatness,
For example, as disclosed in Japanese Patent Publication No. 6-103679, the surface of a work holding plate is coated with acrylic or polycarbonate having a through hole for vacuum suction, and the acrylic or polycarbonate is directly polished before polishing the work. A so-called profile polishing in which a workpiece is polished after the surface state of acrylic or polycarbonate is adjusted to the surface shape of the polishing cloth by polishing with a cloth is disclosed.

Here, an example of a conventional polishing work holding plate is shown in FIGS. 5 (a) and 5 (b). This polishing work holding plate 1
Is composed of a work holding plate body 2 and a work holding plate back plate 5 having a work holding surface 8 and a large number of through holes 4 for vacuum suction, and the through holes 4 are formed by the work holding plate body 2 and the work holding plate back plate. The vacuum path 7 is connected to a vacuum device (not shown) through a space 6 between the space 5, and the work is sucked and held on a work holding surface 8 by generating a vacuum.
Further, the work holding surface 8 of the work holding board body 2 is
Is covered with a resin film 3 having

When polishing the wafer, the work (wafer) is held on the work holding surface 8 of the polishing work holding plate 1 by vacuum suction or the like, and the work is mounted on a polishing head (not shown) having a rotating shaft. The work is pressed against a polishing cloth attached on a surface plate which is rotated by a predetermined load while being rotated by the head. The abrasive is supplied from the nozzle onto the polishing cloth at a predetermined flow rate, and the work is polished by supplying the abrasive between the work and the polishing cloth.

However, when the resin 3 provided with the through holes 4 for vacuum suction is polished, the corners of the holes formed in the resin are rounded, and the diameter of the suction holes (through holes) may gradually increase (see FIG. 1). 5 (C)). When the workpiece is vacuum-held and polished with such a workpiece holding plate, the workpiece is locally deformed around the suction hole, and thus there is a problem that a magic mirror image of the polished workpiece is deteriorated. The magic mirror image is an evaluation method for visually recognizing slight unevenness of a work as a light and dark image. Deterioration of the magic mirror image refers to a state in which the difference in brightness between the bright portion and the dark portion locally increases in the work surface. In such a state, the unevenness is large.

In order to solve this problem, Japanese Patent No. 2588860 discloses a method in which an acrylic plate having a thickness of 3 to 50 mm is provided with a spiral groove having a line width of 0.5 mm or less, and a suction hole is formed at the bottom of the groove. However, since the thickness of the resin is as large as 3 to 5 mm, the rigidity of the surface of the work holding plate is reduced, and there is a problem in that the polishing accuracy of the work is reduced.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above problem. A main object of the present invention is to provide a polishing work holding plate, a polishing apparatus, and a work polishing method capable of obtaining a work having a degree and a magic mirror image.

[0009]

In order to solve the above-mentioned problems, a polishing work holding plate according to the present invention is a polishing work holding plate provided with a work holding plate main body having a through hole for holding a work by vacuum suction. The work holding surface of the holding plate body is coated with a material having a hardness equal to or less than the hardness of the work, and a plurality of pins are formed on the surface of the material with the top surface being a work holding portion. It is a polishing work holding plate (claim 1).

According to the above-structured polishing work holding plate,
By forming a plurality of pins on the surface of the coating that covers the work holding surface of the holding board body, and holding the work by vacuum suction using the pin surface as the work holding part, the suction hole diameter can be expanded even if repeated polishing is repeated. Therefore, the deterioration of the magic mirror image due to the transfer of the surface shape of the holding plate body can be prevented. Further, since the material of the pin is equal to or less than the hardness of the work, there is no possibility that the back surface of the work is scratched or stained by vacuum suction, and a work having a good flatness can be obtained.

A polishing work holding plate according to the present invention is a polishing work holding plate provided with a work holding plate main body having a large number of through holes for vacuum-holding a work, the work holding surface of the holding plate main body. Is coated with a material having a hardness equal to or less than the hardness of the work, and a plurality of beams are formed on the surface of the material, the top surface being a work holding portion. Claim 2).

Thus, for example, on the surface of the coating material,
If a concentric groove is dug, a concentric beam is formed in a convex shape, and this part is used as a work holding part to hold the work by vacuum suction, thereby deteriorating the magic mirror image due to the transfer of the surface roughness of the main body of the holding plate. Can be prevented. In addition, since the material of the beam is equal to or less than the hardness of the work, the work can be polished to a highly flat work without scratches or dirt on the back surface of the work due to vacuum suction.

In these cases, the distance between the centers of the pins in contact with the workpiece (the distance from the center of an arbitrary pin to the center of an adjacent pin) is 1 mm or less and the diameter of the pin is 0.1 mm or less.
It can be 25 mm or more (claim 3). Also,
The distance between the center lines of the beams in contact with the workpiece (the shortest distance from the center line of an arbitrary beam to the center line of an adjacent beam) can be 1 mm or less, and the width of the beam can be 0.25 mm or more. (Claim 4).

[0014] This is because the tip of the pin tends to be rounded into a hemispherical shape or the tip of the beam tends to be rounded into a semi-cylindrical shape by repeating the profile polishing, but when the distance between the centers of the pins is 1 mm or less. When the diameter of the pin is as large as 0.25 mm or more, the work is not deformed between the pins, and in the case of the beam, similarly to the case of the pin, the distance between the center lines of the beam is 1 mm or less. When the width is 0.25 mm or more, the work is not deformed between the beams, and the magic mirror image does not deteriorate.

It is desirable that a through hole for vacuum suction is formed in a portion corresponding to a concave portion on the surface of the coating material. The position of the through hole for vacuum suction is preferably provided in a portion corresponding to a concave portion on the surface of the coating material, that is, in a groove portion between pins or between grooves. This is because, when formed in the portion corresponding to the convex portion, the suction hole is enlarged as in the case where the pin or the beam is not formed, and the magic mirror image is deteriorated. The shape of the concave portion is not particularly limited. However, if the shape of the concave portion is rounded (R-shaped), it is advantageous because dust and the like can be easily removed when the holding plate is washed. .

Further, the hardness of the coating material is measured by a Shore hardness tester D type, which is a kind of rebound type catasa tester, at the temperature when the work holding plate is used (JIS).
Z2246, hereinafter referred to as Shore D hardness)
It is preferably 0 or more (Claim 6), and the coefficient of linear thermal expansion of the coating material is preferably 1 × 10 ⁻⁴ / K or less at the temperature at the time of using the work holding plate (Claim 6). 7).

If the hardness of the coating material is higher than the work hardness, or if the Shore D hardness is lower than 70, the work may be damaged, or the strength of the pins or beams cannot withstand the vacuum pressure, and the linear thermal expansion coefficient is 1 ×. When it exceeds 10 ^-4 / K, minute undulations are generated on the surface of the coating material due to unevenness of the expansion of the pins and beams, which may hinder the vacuum holding of the work and may deteriorate the flatness and the magic mirror image. .

The material of the coating material may be one selected from an epoxy resin, an unsaturated polyester resin, a urethane resin, a phenol resin, and an acrylic resin. If the material of the coating material is selected from the above, it is possible to satisfy the properties of the film after curing, such as Shore D hardness, coefficient of linear thermal expansion, and mechanical strength, required in the present invention. In addition, the thickness of the resin film is 0.5 to 3 mm
(Claim 9). If the thickness of the resin film is 3 mm or less, the rigidity of the main body of the work holding plate is not reduced, so that the work can be polished with higher precision, and if the thickness is 0.5 mm or more, high flatness can be obtained.

It is preferable that the contact area of the coating material per unit area of the work is constant within the work surface. The shapes of the pins and beams formed on the surface of the coating material of the work holding plate are not particularly limited, but the pins are preferably formed as circles (○) or squares (□) because they are easily formed. Further, the beam is not limited to the concentric shape, but may be a pattern such as a lattice shape and a parallel line. At this time, it is preferable that the pattern is such that the contact area of the coating material per unit area of the work becomes constant in the work plane. If the contact area of the coating material per unit area of the work is different in the work surface, the work sinks in a region where the contact area of the coating material is small, and the flatness and the magic mirror image may be deteriorated. .

The invention relating to the work polishing apparatus of the present invention relates to a rotating table to which a polishing cloth is adhered, means for supplying an abrasive to the polishing cloth surface, and a polishing work holding means for forcibly pressing the work against the polishing cloth surface. A polishing apparatus provided with a plate, wherein the polishing work holding plate is as described above.
0).

As described above, the use of the polishing apparatus provided with the work holding plate having the pins and beams formed on the surface makes it possible to process a work having a high flatness and a good magic mirror image. In particular, when the work is a semiconductor wafer, it is possible to reduce a focus defect in lithography exposure in a highly integrated device process and to perform a CMP (Chemic Mechani) process.
The uniformity of the remaining film thickness after cal polishing is also improved, and the yield and productivity of highly integrated devices can be improved.

The method for polishing a work according to the present invention comprises:
The surface of the coating material of the main body of the polishing holding plate described above is brought into contact with the polishing cloth to polish it, and then the back surface of the work is vacuum-adsorbed and held on the surface of the coating material, and the surface of the work is brought into contact with the polishing cloth to make the work It is characterized by being polished (claim 11).

In this polishing method, the surface of the coating material is transferred to the surface of the coating material by previously bringing the surface of the coating material into contact with a polishing cloth, and polishing the surface of the coating material. In addition to the above, it is possible to hold the work without adding stains and dirt, and in addition to this, it is possible to obtain a good magic mirror image without increasing the suction hole diameter gradually, and to manufacture a work with high flatness.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. As described above, when polishing a work, a conventional polishing work holding plate, particularly a holding plate coated with a resin film having a through-hole on the holding surface of the work holding plate main body, is polished by scanning, and the holes formed in the resin are removed. The corners may be rounded, and the diameter of the suction hole may gradually increase. If the work is vacuum-held and polished with such a work holding plate, the work locally deforms around the suction hole, thereby deteriorating the magic mirror image. Happened.

In order to solve these problems, the present inventors have investigated and studied the material and structure of the holding surface of the work holding plate, and as a result, have found that the resin for coating the holding surface of the work holding plate main body has been studied. If the film is polished using a fine pin (and concave portion) or beam (and groove) for suction, formed separately from the through-hole for vacuum suction, the diameter of the suction hole hardly increases, After that, even if the work was polished, it was found that local deformation did not occur around the suction hole, and a good magic mirror image was obtained.

First, a polishing apparatus using the polishing work holding plate of the present invention will be described with reference to the drawings. Here, FIG. 1 is a schematic explanatory view for explaining a configuration outline of a polishing work holding plate as an example of the present invention. FIGS. 2A and 2B are explanatory diagrams for explaining the outline of the configuration of a polishing head equipped with a polishing work holding plate, and FIG. 2B showing the configuration of a polishing apparatus having a polishing head.

The polishing apparatus of the present invention is configured as an apparatus for polishing one side of a work, for example, a semiconductor wafer.
As shown in (b), the polishing apparatus 20 includes a rotating platen (rotary table) 21, a polishing work holding plate 1 mounted on the polishing head 10, and a polishing agent supply nozzle 23. A polishing cloth 22 is attached to the upper surface of the surface plate 21. The platen 21 is rotated at a predetermined rotation speed by a rotation shaft.

Then, the work holding plate 1 holds the work (wafer) W on the work holding surface 8 by vacuum suction or the like.
The workpiece W is mounted on the polishing head 10 having a rotation axis, rotated by the polishing head 10, and simultaneously presses the workpiece W against the polishing cloth 22 with a predetermined load. The abrasive 24 is supplied from the nozzle 23 onto the polishing cloth 22 at a predetermined flow rate. The abrasive 24 is supplied between the work W and the polishing cloth 22 to polish the work W.

Further, as shown in FIGS. 1 and 2A, the polishing work holding plate 1 of the present invention has a work holding surface 8 and a plurality of through holes 4 for vacuum suction. 2 and a work holding plate back plate 5, and the through hole 4 is connected to a vacuum device (not shown) from the vacuum path 7 through a space 6 between the work holding plate body 2 and the work holding plate back plate 5, The work W is sucked and held on the work holding surface 8 by generation of a vacuum.

In the present invention, in particular, the work holding surface 8 of the work holding board main body 2 has a plurality of pins 9 or beams (16 in FIG. 3).
Are coated with the coating material 3 formed with The through-holes 4 are provided in a region within a dotted line in FIG. Further, the pins or beams are formed so that the contact area per unit area of the work of the work holding surface formed of pins or beams is constant at least within the plane of the work. The method of forming the pin or beam is not particularly limited, but a method of machining into an arbitrary pin or beam pattern, pressing a mold, and the like,
It can be formed by various methods.

Further, in order to make the contact area constant, as shown in FIG.
It is preferable that the inner diameter d of No. 5 is larger than the diameter Dw of the work. On the contrary, the inner diameter d of the outer peripheral portion 15 of the work holding surface 8
Is smaller than the diameter Dw of the work, the area where the outer peripheral portion of the work contacts the outer peripheral portion of the holding surface becomes large and is not constant, so that the work sinks in a region where the contact area of the coating material is small, This is because the flatness and the magic mirror image deteriorate (FIG. 4B).

The polishing head 10 has a pressurized space 13 provided inside its rotary holder 11, and holds the polishing work holding plate 1 airtight through an elastic ring 12. The pressurizing space 13 is connected to an air compressor (not shown) via a pressurizing path 14. Then, the work W is rotated or oscillated on the work holding plate 1 that holds the work W by vacuum suction on the surface of the coating material 3 on which the pins or beams are formed on the work holding surface 8, and at the same time, the back surface of the work holding plate 1 is air-flowed. The work holding plate 1 holding the work is pressed against the polishing pad 22 by pressing.

When the profile polishing is performed using the polishing work holding plate of the present invention configured as described above, the diameter of the through hole for suction hardly increases. This does not cause any significant deformation, a good magic mirror image of the polished work is obtained, and a work with high flatness can be obtained.

As described above, the polishing work holding plate of the present invention is a polishing work holding plate provided with a work holding plate main body having a large number of through holes for holding a work by vacuum suction. Is coated with a material having a hardness equal to or less than the hardness of the work, and a plurality of pins or beams are formed on the surface of the material, the top surface being a work holding portion.

In the case of a pin, the surface of the pin is used as a work holding portion to hold the work by vacuum suction, thereby preventing deterioration of the magic mirror image due to transfer of the surface roughness of the holding plate body. Further, since the material of the pin is equal to or less than the hardness of the work, there is no possibility that the back surface of the work may be scratched or stained by vacuum suction.

If a concentric groove as shown in FIG. 3, for example, is dug in the surface of the coating material, a concentric beam is formed in a convex shape, and the surface of the beam is used as a work holding portion to vacuum-suck the work. By holding, it is possible to prevent the deterioration of the magic mirror image due to the transfer of the surface roughness of the holding plate body, and since the material of the beam is equal to or less than the hardness of the work, the back surface of the work is scratched or stained by vacuum suction. It can be polished to a work with a high flatness without sticking.

In this case, the distance between the centers of the pins in contact with the work is 1 mm or less, and the diameter of the pins is 0.25 m.
m or more, and the distance between the center lines of the beams in contact with the workpiece is 1 mm or less, and the width of the beams can be 0.25 mm or more.

The reason for this limitation is that copy polishing is performed, that is, the surface of the coating material of the holding plate body is polished by bringing the surface of the coating material into contact with a polishing cloth before the workpiece is polished. If the surface of the work is polished by a method in which the back surface of the work is held by vacuum suction and the work surface is brought into contact with the polishing cloth, the polishing cloth shape is transferred to the surface of the coating material by polishing the surface of the coating material in advance. When the work is held, the work can be held without scratches or dirt on the back surface of the work, high flatness can be achieved, and a good magic mirror image can be obtained. However, by repeating this copying and polishing, the tip of the pin tends to be rounded into a hemispherical shape, or the tip of the beam tends to be rounded into a semi-cylindrical shape. Therefore, if the distance between the centers of the pins is set to 1 mm or less and the diameter of the pins is set to 0.25 mm or more, the work does not deform between the pins. In the case of the beam, as in the case of the pin, if the distance between the center lines of the beam is set to 1 mm or less and the width of the beam is set to 0.25 mm or more, the work is deformed between the beams, and The mirror image does not get worse.

It is desirable that a through hole for vacuum suction is formed in a portion corresponding to a concave portion on the surface of the coating material. That is, the position of the through hole for vacuum suction is preferably provided in a portion corresponding to a concave portion on the surface of the coating material, that is, in a groove portion between pins or a groove portion between beams. This is because, when formed in the portion corresponding to the convex portion, the suction hole is enlarged as in the case where the pin or the beam is not formed, and the magic mirror image is deteriorated.

Further, the hardness of the coating material is preferably 70 or more in Shore D hardness at the temperature at the time of using the work holding plate, and the linear thermal expansion coefficient of the coating material is as follows:
It is desirable that the temperature be 1 × 10 ⁻⁴ / K or less at the temperature when the work holding board is used. If the hardness of the coating material is less than 70 in Shore D hardness, the strength of the pins and beams cannot withstand the vacuum pressure, and if the coefficient of linear thermal expansion exceeds 1 × 10 ^-4 / K, the expansion of the pins and beams will occur. This is because fine undulation is generated on the surface of the coating material due to the variation, and this hinders the vacuum holding of the work and deteriorates the flatness and the magic mirror image.

The material of the coating material of the present invention can be, for example, one selected from an epoxy resin, an unsaturated polyester resin, a urethane resin, a phenol resin, and an acrylic resin. If the material of the coating material is selected from the above, it is possible to satisfy the properties of the film after curing, such as Shore D hardness, coefficient of linear thermal expansion, and mechanical strength, required in the present invention. Further, the thickness of the resin film is desirably 0.5 to 3 mm.

[0042]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples of the present invention, but the present invention is not limited thereto. (Test 1) [Investigation of the material of the work holding surface and the distance between the centers of the pins] The silicon wafer was polished under the following conditions, and the polished surface was evaluated. (1) The polishing work holding plate used had a pin-shaped structure as shown in FIG. 1 and the polishing device used had a structure shown in FIG. 2 (b). (2) Work: silicon wafer: diameter 200 mm, thickness 735 μm. (3) Work holding board main body: 30 mm thick silicon carbide ceramic porous board: hole diameter 0.5 mm, coefficient of linear thermal expansion 4 ×
10 ^-6 / K. (4) Work holding surface: silicon carbide ceramics, silicon mirror surface wafer, and resin having Shore D hardness of 80. (5) Surface shape of work holding surface: pins are formed in a lattice; intervals between pin centers 1.10, 1.00, 0.80, 0.7
Four levels of 0 mm; pin diameter of 0.35 mm; seal for vacuum holding formed at the portion where the outer peripheral portion of the wafer is in contact. (6) Work polishing conditions: load 300 g / cm ² ; polishing relative speed 50 m / min; polishing allowance 10 μm; polishing cloth:
Nonwoven fabric polishing cloth (Asker C hardness: a value measured by an Asker rubber hardness tester Model C, which is a kind of spring hardness tester: 90); Abrasive: Colloidal silica (pH = 10.
5). (7) Evaluation of polished surface: After performing a known cleaning on the polished wafer, a scratch inspection of the back surface of the wafer under a condensing lamp and a magic mirror image level by a magic mirror measuring device (SC-13, manufactured by NIDEK) are performed. An evaluation was performed.

As a result of the above test, contact marks of the pins were found on the back surface of the wafer polished using the work holding plate having the pins formed on the surface of the SiC ceramic. In the wafer polished using the holding plate, no contact trace of the pin was observed on the back surface of the wafer. The distance between the pin centers is 1.0mm
In the following cases, a good magic mirror image was obtained, but 1.10 mm
At the time, the level of the magic mirror image was reduced due to the deformation of the wafer.

(Test 2) [Investigation of Spacing Between Beam Center Lines When Beams Are Formed] (1) A polishing work holding surface having a concentric beam structure shown in FIG. 3 was used. (2) Work holding surface: resin coating with Shore D hardness of 80. (3) Resin surface shape: beam formation (digging grooves to make beams);
Spacing between beam centerlines 1.10, 1.00, 0.80,.
Four levels of 70 mm; beam width of 0.35 mm; seal for vacuum holding formed at the part where wafer outer peripheral part is in contact. The other conditions were the same as in Test 1, and the test was performed to evaluate the magic mirror image level.

When the distance between the beam center lines was 1.00 mm or less, a good magic mirror image was obtained. However, when the distance was 1.10 mm, the deterioration of the magic mirror image due to the deformation of the wafer was sometimes observed. Was.

(Test 3) [Investigation of Influence of Hardness of Coating Material] (1) A polishing work holding plate having a pin structure shown in FIG. 1 was used. (2) Work holding surface: Shore D hardness 60, 65, 70,
80 resin coating 4 levels. The other conditions were the same as in Test 1, and the test was performed. A magic mirror image level and a capacitance type flatness meter (ULTRA GAGE 9700, AD
(Manufactured by E Company) to evaluate the flatness.

When a resin having a Shore D hardness of 60 or 65 was used, detachment of the wafer due to deformation of the pin often occurred during polishing. In addition, even when the wafer did not detach, undulation was observed mainly in the vicinity of the through hole for vacuum suction by the flatness measurement. On the other hand, Shore D hardness is 70,
When the resin No. 80 was used, the wafer could be polished without any problem, and no undulation was observed on the wafer.

(Test 4) [Investigation of Influence of Linear Thermal Expansion Coefficient of Resin] (1) The polishing work holding surface used had the pin structure shown in FIG. (2) Work holding surface: Shore D hardness 80 resin coating. (3) Linear thermal expansion coefficient of resin: 5 × 10 ^-4 / K, 1 × 1
Four levels of 0 ^-4 / K, 5 × 10 ^-5 / K and 9 × 10 ^-6 / K.
Otherwise, the test was performed under the conditions of Test 1, and the magic mirror image level and the flatness were evaluated.

When a resin having a linear thermal expansion coefficient of 5 × 10 ⁻⁴ / K was used, undulation was observed on the wafer due to the thermal expansion of the resin which was considered to be caused by polishing heat. On the other hand, when a resin having a linear thermal expansion coefficient of 1 × 10 ⁻⁴ / K or less was used, no undulation was observed on the wafer, and a good magic mirror image was obtained.

(Test 5) [Investigation of the influence of the thickness of the resin film] (1) Work holding surface: thermosetting epoxy resin (Shore D)
(2) Resin linear thermal expansion coefficient: 5 × 10 ^-5 / K, (3) Resin thickness: 0.2, 0.5, 1, 3, 4 mm The test was performed under the conditions, and the magic mirror image level and the flatness were evaluated.

When the thickness of the resin is 0.2 mm, a part of the resin film may be broken due to insufficient strength of the resin film. When the thickness of the resin is set to 4 mm, the resin may be deformed depending on the polishing heat, the magic mirror image may be deteriorated, and the flatness may be reduced by SBIRmax (Site Back-s).
ide Ideal Range: a value standardized by SEMI standard M1 or the like, cell size 25 × 25).
It was about 5 μm. On the other hand, when the thickness of the resin is 0.5 to 3 m
m, there is no problem with the magic mirror image and the flatness is also SBI
Rmax of about 0.25 μm was obtained, which was particularly suitable.

(Test 6) [Shape of Work Holding Surface] (1) Work holding surfaces for polishing used two types of shapes shown in FIGS. 4 (a) and 4 (b). That is, (a)
Is a holding surface (Dw <d) in which pins are formed in a circle having an inner diameter of 203 mm at the outer peripheral portion of the work holding surface, and (b) shows an inner diameter of 1 mm.
It is a holding surface (Dw> d) in which a pin is formed within a 50 mm circle. Here, Dw is the diameter of the wafer (work) of 20.
0 mm and d are the inner diameters of the outer peripheral portion of the work holding surface. (2) Work holding surface: Shore D hardness 80 resin coating. Otherwise, the test was performed under the conditions of Test 1, and the magic mirror image level and the flatness were evaluated.

When the work holding surface shown in FIG. 4B is used,
A reduction in the polishing allowance was observed in a portion corresponding to a diameter of 150 mm, and the wafer had a top hat shape. on the other hand,
When the work holding surface shown in FIG. 4A was used, there was no problem in the wafer shape, and a desired flatness was obtained. The level of the magic mirror image was also good.

(Examples and Comparative Examples) [Presence / absence of profile polishing, effect of pin formation in profile polishing] (1) The polishing work holding surface shown in FIGS. 1 and 5 was used. That is, FIG. 1 shows a holding surface on which pins are formed on the work holding surface of the present invention, and FIG. 5 shows a holding surface on which no pins are formed on the conventional work holding surface. (2) Work holding surface; resin coating with Shore D hardness of 80. (3) Work holding surface polishing conditions: For each work holding surface, a. No work holding surface polishing, b. The resin film polishing amount was 200 μm under the same conditions as the work polishing conditions. Otherwise, the test was performed under the conditions of Test 1, and the level of the magic mirror image and the flatness were evaluated.

As a result, when the flatness of the work was compared with the surface-based SBIRmax, the SBIRmax when the work holding surface was not polished (without copy polishing) was 0 regardless of the presence or absence of pin formation. Although it was about 30 .mu.m, an SBIRmax of 0.20 .mu.m was obtained by introducing polishing of the work holding surface (with copy polishing).
On the other hand, comparing the magic mirror level when the work holding surface was polished, the trace of the suction hole was clearly observed in the case of the work holding surface where no pin was formed (Comparative Example). A good magic mirror image was obtained on the work holding surface (Example) in which was formed.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

[0057]

As described above, according to the present invention,
A polishing work holding plate having a highly accurate work holding surface is provided. Therefore, by performing polishing using this, not only excellent flatness can be obtained, but also a work having a good magic mirror image level can be obtained. In particular, when the work is a semiconductor wafer, a CMP (Chemical Mechanical), which is considered to be poorly focused in lithography exposure in a highly integrated device process or is recently being introduced.
It is possible to reduce various film thickness defects in the (1 Polishing) process, and to improve the yield of highly integrated devices.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a polishing work holding plate of the present invention. (A) longitudinal sectional view, (b) front view of a work holding surface, (c)
7 shows a change state of a peripheral holding surface around a through-hole for vacuum suction due to profile polishing.

FIG. 2 is a schematic explanatory view of a polishing head equipped with a polishing work holding plate of the present invention and a polishing apparatus provided with the polishing head. (A) a polishing head, and (b) a work polishing apparatus.

FIG. 3 is a front view of a work holding surface showing another example of the polishing work holding board of the present invention (when a beam is formed).

FIG. 4 is a longitudinal sectional view showing a difference in a contact area between a work holding surface of a polishing work holding board and a work. (A) When the diameter of the work is smaller than the inner diameter of the outer periphery of the work holding surface, and (b) when the diameter of the work is larger than the inner diameter of the outer periphery of the work holding surface.

FIG. 5 is a schematic explanatory view showing an example of a conventional polishing work holding plate. (A) longitudinal sectional view, (b) front view of a work holding surface, (c)
7 shows a change state of a peripheral holding surface around a through-hole for vacuum suction due to profile polishing.

[Explanation of symbols]

1. Polishing work holding plate 2. Work holding plate body 3,
... Coating material (resin), 4 ... Vacuum suction through hole, 5 ...
Back plate of work holding board, 6: space, 7: vacuum path,
8: Work holding surface, 9: Pin, 10: Polishing head,
DESCRIPTION OF SYMBOLS 11 ... Rotation holder, 12 ... Elastic body ring, 13 ... Pressurization space part, 14 ... Pressurization path, 15 ... Work holding surface outer peripheral part, 16 ... Beam, 20 ... Polishing device, 21 ... Surface plate, 22
... polishing cloth, 23 ... nozzle, 24 ... abrasive. W: work (wafer), Dw: diameter of work, d: inner diameter of work holding surface outer periphery.

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Claims (12)

[Claims] 1. A polishing work holding plate provided with a work holding plate body having a through hole for holding a work by vacuum suction, wherein a work holding surface of the holding plate body is covered with a material having a hardness equal to or less than the hardness of the work. A polishing work holding plate, comprising a plurality of pins formed on a surface of the material and having a tip surface as a work holding portion. 2. A polishing work holding plate having a work holding plate main body having a through hole for vacuum-sucking and holding a work, wherein a work holding surface of the holding plate main body is coated with a material having a hardness equal to or lower than the hardness of the work. A polishing work holding plate, characterized in that a plurality of beams are formed on the surface of the material, with the top surface being a work holding portion. 3. The polishing work holding plate according to claim 1, wherein the distance between the centers of the pins in contact with the work is 1 mm or less, and the diameter of the pins is 0.25 mm or more. 4. The polishing work holding plate according to claim 2, wherein the distance between the center lines of the beams in contact with the work is 1 mm or less, and the width of the beams is 0.25 mm or more. . 5. The polishing work according to claim 1, wherein the through-hole for vacuum suction is formed in a portion corresponding to a concave portion on the surface of the coating material. Holding board. 6. The polishing method according to claim 1, wherein the hardness of the coating material according to any one of claims 1 to 5 is 70 or more in Shore D hardness at a temperature when the work holding plate is used. Work holding board. 7. The coating material according to any one of claims 1 to 6, wherein the coefficient of linear thermal expansion is 1 × 10 ⁻⁴ / K or less at a temperature when the work holding plate is used. A polishing work holding board characterized by the following. 8. The method according to claim 1, wherein the coating material is one selected from an epoxy resin, an unsaturated polyester resin, a urethane resin, a phenol resin, and an acrylic resin. The polishing holding plate described in the section. 9. The polishing work holding plate according to claim 8, wherein the thickness of the resin film covering the holding surface of the work holding plate main body is 0.5 to 3 mm. 10. The polishing work holding plate according to claim 1, wherein a contact area of the coating material per unit area of the work is constant in a work surface. . 11. A polishing apparatus comprising: a rotary table to which a polishing cloth is adhered; means for supplying an abrasive to the polishing cloth surface; and a polishing work holding plate for forcibly pressing a work against the polishing cloth surface. 2. The work holding board according to claim 1, wherein
A workpiece polishing apparatus according to any one of claims 10 to 10. 12. A polishing material is polished by contacting the surface of the coating material of the main body of the holding plate for polishing according to any one of claims 1 to 10 with a polishing cloth, and then applying a vacuum to the back surface of the work on the surface of the coating material. A polishing method for a workpiece, comprising: holding the workpiece by suction, bringing the surface of the workpiece into contact with a polishing cloth, and polishing the workpiece.