JPS58180026A - Attracting board for grinding wafer - Google Patents

Abstract

PURPOSE:To stick the outer circumference of the wafer fast and hold it and prevent the intrusion of a grinding liquid, and to improve the accuracy of the wafer ground by arranging a rubbery elastic body around a thick board. CONSTITUTION:A rubbery elastic body 10 is disposed while tightly surrounding the outer circumference of the attracting board 6 arranged onto a base plate 3, the leakage of air from the side surface of the attracting board 6 is prevented and the outer circumference of the wafer 5 is fast stuck, but the wafer 5 is not fast stuck, and is projected previously only by height d from the surface of the attracting board 6 under the state in which grinding pressure is not applied. With the attracting board 6, a plurality of extremely thin grooves 61 are notched to the surface while it can be sucked under vacuum by large holes 8 for suction communicating at the bottom, and a diameter on the surface side is made slightly smaller than that of the wafer 5. When a vacuum system switch is turned ON under the state, the back of the wafer 5 is fast stuck onto the surface of the attracting board 6, but the outer circumferential section is projected slightly, and the surface of the rubbery elastic body 10 of the outer circumference of the wafer 5 is deformed, the upper surface is made the same plane as the surface of the attracting board 6 and the wafer 5 is ground flatly when a grinding disk is fast stuck to the wafer 5 and grinding pressure is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a wafer polishing suction &
KII.

When manufacturing wafers, II! Surface treatment processes such as wrapping and polishing exist to remove the rain-destroyed layer and obtain a defect-free single crystal surface. When polishing a wafer in this process, the wafer is placed and fixed on a suction plate. Conventional suction plates include those using I-glass ceramics, thick plates with holes drilled in them, and I-glass plates. ! Those whose surfaces were coated with a layer of oil were used. Fig. 1 is based on I-lase ceramics, in which a porous ceramic 1 is placed on a mounting table 3 having suction holes 2, and a hard resin 4 is placed around the outer periphery of the porous ceramics 1 to close the suction holes. It is located. In order to match the workability with this hard resin 4Fi porous ceramic l, it is filled with hard and brittle powder. When grinding or rugging the surface of the I-las ceramics I, the surface with the hard resin is also formed without unevenness, similar to the I-las ceramics XOH surface. However, due to the hard resin and the surface condition of the porous ceramics 1, the polishing liquid infiltrates from the outer periphery of the wafer 50 adsorbed on the I-las ceramics 1, and in the case of 4 lithinda using a chemical source, #'i infiltrated liquid This has the disadvantage that the back surface of the wafer 5 is corroded and minute irregularities are generated, resulting in a wafer 5 that is unsatisfactory in appearance. In addition, even if the back surface of I-Lasseroxelox l-c#i is ground or camel-finished, it may have roughness or unevenness of 10 figs or more, making it difficult to match with the ground metal surface of the mounting table 3, and it may not be completely finished. Since it cannot be attached closely, I-Las ceramics l and mounting table 3
There was a drawback that a minute gap was generated between the surfaces of the wafer 5 and the processing accuracy of the wafer 5 was reduced.

FIG. 2 shows an example in which a metal suction plate 6 is placed on the Fi mounting table 3, and a Ka quota pore 7 and a large suction hole 8 are provided in the metal suction plate 6. In such an example, the metal suction plate 6! ! ! Since the suction pores 7 that appear in the opposite direction cannot be formed all the way to the outer peripheral edge of the wafer 5, the outer periphery of the wafer 5 does not come into close contact with the wafer 5 during polishing, resulting in a disadvantage that the polishing liquid may enter and the precision of the polished wafer is reduced.

In addition, FIG. 3 shows a model in which the surface of the metal suction plate 60 shown in FIG. 2 is coated with a resin film 9, which improves the adhesion to the wafer 5 and prevents the polishing liquid 5 from penetrating into the back surface of the wafer 5. This is an example. However, since it is difficult to obtain a uniform thickness of the resin film 9 during processing, there is a drawback that the processing N degree of the wafer 5, particularly the parallelism, is low.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the present invention aims to provide a suction plate for wafer polishing which prevents the infiltration of polishing liquid and at the same time improves processing accuracy.

In order to achieve this object, the present invention involves carving a plurality of narrow grooves or #i pores on the surface of a thick plate having an outer dimension slightly smaller than that of the wafer to be processed. Suction holes that communicate with the bottoms of the pores are bored from the back side of the thick plate, while a rubber-like elastic body is tightly surrounded on the entire outer periphery of the thick plate, and this rubber-like (elastic body is attached to the surface of the thick plate). % mold is defined as having a more minute dimension protrude.

No. 4i is an example of a suction plate for wafer polishing according to the present invention,
The same parts as in FIGS. 1 to ji311 are given the same reference numerals. A rubber-like elastic body 10 is arranged so as to closely surround the outer periphery of the g & mounting plate 6 placed on the mounting table 3. This rubber-like elastic body 1G
is to prevent air leakage on one side of the scattering plate 1ii and to tightly fit the outer periphery of the wafer 5. exists for the sake of In addition, this rubber-like elastic body 1υ is attached to the suction plate 1 in a state where the wafer 5 is not brought into close contact with the suction plate 1υ and no polishing pressure is applied.
It protrudes slightly from the 0 surface by a height d.

Adsorption plate 6 itself K Id its I! ilK multiple ultra-fine grooves 6
1 is engraved and a large suction hole 8 communicating with the bottom of this ultra-thin groove 61 is provided to enable vacuum suction. The wafer 5 is only -1 PK smaller, so the #jk signboard 6 is removed from the #jk signboard 6 while the wafer 5 is placed.
This will be related to part 1.

When the wafer 5 is placed on the suction plate 6 and the vacuum system switch is turned on, the back side of the wafer 5 is brought into close contact with the front surface of the Ti plate 60, but the outer circumference of the wafer 5 is warped by 5t-t. Next, when the polishing disk is brought into close contact with the wafer 5 and polishing pressure is applied,
The am of the rubber-like elastic body 10 on the outer periphery of the wafer 5 is deformed so that the upper surface of the rubber-like elastic body 10 becomes flush with the surface of the suction plate 6, and the wafer 5 is polished into a flat surface.

The following KA# example is shown below. Use stainless steel as the material of the suction plate 6 - 576φ ■ The diameter of the suction plate 6 is 72mm for the Kuha 5
I'll be respectful. Surface K @ 0.2■, depth 1 inch thin groove 6
1 are placed in one direction, and a urethane rubber cylinder is glued to the outer periphery as a rubber-like elastic body 10. When the suction plate 6 is rotated once while grinding the urethane rubber and stainless steel at the same time with a straight grindstone (WA S100), the urethane rubber part protrudes 3 to 5 μm from the surface of the stainless steel grade plate after grinding. Ta. Place wafer 5 on top of this,
When the suction was carried out at a pressure of 70 mm or more, the height of the central part of the outer circumferential portion 3 of the wafer 5 was 2 to 3 m. When the wafer 5 attracted in this way is polished, the wafer 5 excluding the outer peripheral edge 2
The parallelism Fi was less than 2 μm, and the variation in thickness at the outer peripheral edge was less than 111vt with respect to the inside of the center.

In addition, no infiltration of the polishing liquid into the wafer 5 (D@ surface) was observed. In this case, the urethane rubber had a rubber hardness of 55 to 10.
When we similarly considered various rings in the range of 0, we found that
The protrusion height of the soft type #1 tends to be higher, and the protrusion height of each pole cylinder was in the range of 40 to 2 tones.When the wafer 5 attached to each pole was polished, the above concrete The same effect as in the example was obtained.

Furthermore, in the above specific example, the suction surface portion other than the narrow groove 61 on the suction (stainless steel) plate 6 is provided on the outer periphery with a glass material such as Teflon, nylon, or high-grade plastic material that is harder than urethane rubber. After coating with hard polyurethane, the suction surface side was ground and coated in the same way, and the thickness of the glass stick was approximately 101 * tone ~ several 10 J! As a result, the protruding height of the urethane rubber disposed on the outer periphery was reduced by 30 to 50% compared to the specific example described above. When the adsorbed wafer 5 is polished using this, the parallelism of the wafer excluding the outer periphery zIII is about 1 to 2 degrees, and the thickness variation at the outer periphery edge is 1 μ or less compared to the inside of the center. Of course, no penetration of the polishing liquid into the back surface of the wafer 5 was observed, and the same effect as in the above-mentioned example was obtained. Moreover, the suction force during polishing increased, and the back side Wi (suction 1i1i@) of the wafer 5 was not scratched at all.

In the above embodiment, the case where the suction plate 6 and the narrow groove 61 are applied has been explained, but a plurality of fine holes may be provided instead of the thin groove 61. It also becomes possible to apply glass ceramics.

As explained above, according to the present invention, by arranging the rubber-like elastic body around the thick plate, the outer periphery of the wafer is held tightly and stably held, preventing infiltration of polishing liquid, and improving the precision of polished wafers. can. In particular, when the suction plate is made of stainless steel, it can be ground into a parallel flat plate with both flatness and parallelism of 1 μm or less, resulting in excellent flatness and parallelism of the wafer.

[Brief explanation of the drawing]

Figures 1 to 3 show three examples of conventional suction plates for polishing. 1ai2 uses I-las ceramics, Figure 2 uses a metal suction plate, and Figure 3 uses a resin film. The configuration diagram showing an example using jiE4 diagram is the original F! A.K.
1 is a partially cutaway perspective view of an embodiment of a suction plate for wafer polishing according to the present invention. In the drawings, 5 is a wafer, 6 is a suction plate, 10 is a rubber-like elastic body, and 61U thin grooves. Patent applicant Nippon Telegraph and Telephone Public Corporation Patent attorney Shibu Mitsuishi (and 1 other person) Figure 1 Figure 2

Claims (2)

[Claims] (1) A plurality of JII grooves or pores are carved in the front surface of a thick plate having external dimensions slightly smaller than the external dimensions of the wafer to be processed, and suction holes communicate with the bottoms of the narrow grooves or pores. is drilled from the am of the thick plate, while a comb-shaped elastic body is closely surrounded on the entire outer periphery of the thick plate, and this pom-shaped elastic body is made to protrude from the surface of the thick plate by a minute dimension at the center. Adsorption plate for wafer polishing. (2) The suction for wafer polishing according to claim 1, wherein the surface of the thick metal plate is coated with an extremely thin glass material that is harder than the rubber-like elastic body of EiIK other than the narrow grooves or pores. Board.