JP2015112678A - Polishing carrier for crystal wafer and polishing method of crystal wafer using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing carrier for a crystal wafer suppressing the damage of the crystal wafer when polishing the crystal wafer by a double-sided polishing machine.SOLUTION: A polishing carrier 10 is used when a crystal wafer 20 is polished by a double-sided polishing machine 30 and has a storage hole 11 to hold the crystal wafer 20. An inside wall 12 of the storage hole 11 is coated with a resin 13. The damage of the crystal wafer 20 can be suppressed since a force applied to the crystal wafer 20 from the storage hole 11 is moderated by the resin 13 due to the coating of the inside wall 12 of the storage hole 11 with the resin 13 in the polishing carrier 10 when polishing the crystal wafer 20 by the double-sided polishing machine 30.

Description

  The present invention relates to a quartz wafer polishing carrier (hereinafter simply referred to as “polishing carrier”) used in a double-side polishing machine, and a method for polishing a quartz wafer using the same.

  In order to obtain a quartz wafer from a lump of quartz that is a brittle material, for example, the following steps (1) to (9) are required.

(1) Accepting crystal ingots (blocks)
(2) Angle measurement (because the cut angle is important)
(3) Pasting (to put into cutting machine)
(4) Cutting
(5) Outline processing
(6) Polishing
(7) Angle measurement (because the cut angle is important)
(8) Polish (finish polishing)
(9) Cleaning and inspection

  Among these, as an example of (4), there is a cutting method using a wire saw (or blade saw). In this method, a wire is pressed against a quartz ingot while supplying a slurry containing loose abrasive grains, and then cut. Therefore, at the initial stage of cutting, the wire cannot be quickly cut into a hard ingot, and the cut surface of the crystal may be damaged. This damage appears as cracks or chipping in the quartz wafer. The damage thus generated cannot be removed in the next polishing process. Rather, in the polishing process, a portion deteriorated by damage at the time of cutting causes new damage, so that the end face of the crystal wafer becomes rougher than at the time of cutting.

  Since the end face of the crystal wafer after cutting is damaged to some extent, a step called (5) outer shape processing is required. In this process, a plurality of quartz wafers are laminated, a resin is infiltrated between them to form a quartz wafer laminate, and the end face of the quartz wafer laminate is subjected to fine processing (grinding, polishing, polishing, etc.) Damage to the wafer end face is removed, and then the resin is removed with a stripping solution to separate the wafers one by one. However, even if the damage to the crystal wafer end face is eliminated in this way, the subsequent process (6) polishing and (8) polish will still apply excessive force to the crystal wafer end face during processing. New damage may occur.

  In particular, when a quartz wafer is polished or polished by a double-side polishing machine having a planetary gear mechanism, the quartz wafer is easily damaged. This is because the end face of the crystal wafer and the inner wall of the wafer storage hole collide when the crystal wafer is put into the wafer storage hole of the polishing carrier and polished or polished.

Japanese Patent Laying-Open No. 2010-280026 (FIG. 3 “Buffer Ring 53”) Japanese Unexamined Patent Publication No. 2011-240460 (FIG. 3 “Resin Ring 2”)

  In the field of polishing a semiconductor wafer with a double-side polishing machine, it is known to use a polishing carrier in which a resin ring is attached to the inner wall of a wafer housing hole in order to reduce damage to the semiconductor wafer during polishing (Patent Document). 1 and 2). This is a technique suitable for holding and polishing a semiconductor wafer having a thickness of 0.5 to 1 mm or more because it has a structure in which a resin ring is fitted into the inner periphery of a metal wafer storage hole. However, in the case of a crystal wafer having a thickness of 0.1 mm or less, in order to realize a structure in which a resin ring is attached so that the crystal wafer can be held and polished in the thickness direction of the polishing carrier, for example, the engagement formed on the inner wall of the wafer accommodation hole It is difficult to see from the point of processing a shape suitable for the above.

  Therefore, an object of the present invention is to provide a polishing carrier or the like that suppresses damage to the crystal wafer when the crystal wafer is polished by a double-side polishing machine.

The abrasive carrier according to the present invention is:
Used when polishing a quartz wafer by a double-side polishing machine, in a polishing carrier having a storage hole for holding the quartz wafer,
The inner wall of the storage hole is coated with resin,
It is characterized by that.

The method for polishing a quartz wafer according to the present invention includes:
By holding the crystal wafer in the storage hole of the polishing carrier according to the present invention, the crystal wafer is held in the storage hole in a state where the end surface of the crystal wafer is in contact with the inner wall covered with the resin,
Polishing the quartz wafer together with the polishing carrier using the double-side polishing machine,
It is characterized by that.

  According to the present invention, since the inner wall of the storage hole of the polishing carrier is coated with the resin, the force that the crystal wafer receives from the storage hole when the crystal wafer is being polished by the double-side polishing machine can be relaxed by the resin. Wafer damage can be suppressed. In addition, since the inner wall of the storage hole of the polishing carrier is only covered with resin, it can be easily applied to a crystal wafer that needs to be thinned as compared with a structure in which a resin ring is fitted into the inner periphery of the storage hole.

FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line Ib-Ib in FIG. 1A, showing the polishing carrier of Embodiment 1. FIG. 2A is a plan view and FIG. 2B is an enlarged view of a portion IIb in FIG. 2A, showing a part of the double-side polishing machine. 6 is a plan view showing a process on the polishing carrier side in the polishing method of Embodiment 2. FIG. FIG. 6 is a perspective view and a plan view showing a process on a crystal wafer side in the polishing method of Embodiment 2.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the accompanying drawings. In the present specification and drawings, the same reference numerals are used for substantially the same components. The shapes depicted in the drawings are drawn so as to be easily understood by those skilled in the art, and thus do not necessarily match the actual dimensions and ratios.

  FIG. 1 shows a polishing carrier of Embodiment 1, FIG. 1 [A] is a plan view, and FIG. 1 [B] is a cross-sectional view taken along line Ib-Ib in FIG. 1 [A]. 2 shows a part of the double-side polishing machine, FIG. 2A is a plan view, and FIG. 2B is an enlarged view of a portion IIb in FIG. 2A. However, in FIG. 1B, a crystal wafer is added and the thickness direction is enlarged with respect to the plane direction. Hereinafter, description will be given based on these drawings.

  The polishing carrier 10 according to the first embodiment is used when the crystal wafer 20 is polished by the double-side polishing machine 30 and has a storage hole 11 that holds the crystal wafer 20. The inner wall 12 of the storage hole 11 is covered with a resin 13. The accommodation holes 11 are through-holes having a size capable of accommodating the crystal wafer 20 and the number thereof is arbitrary. Further, a gear portion 14 is formed on the outer periphery of the polishing carrier 10, and a polishing liquid passage hole 15 is formed inside the polishing carrier 10. The end face 21 of the crystal wafer 20 may be covered with a resin 22. The end face 21 of the crystal wafer 20 is the peripheral edge of the crystal wafer 20.

  In addition to the sun gear 31 and the internal gear 32, the double-side polishing machine 30 includes an upper surface plate, a lower surface polishing cloth, a drive source, and the like (not shown). In FIG. 2, the gear portions of the gears are not shown. The sun gear 31 and the internal gear 32 are located between the upper surface plate and the lower surface plate, and the polishing carrier 10 is meshed between the sun gear 31 and the internal gear 32 as a planetary gear. When the quartz wafer 20 is set on the polishing carrier 10, these are sandwiched by the upper and lower surface plates via the polishing cloth, and the sun gear 31 or the internal gear 32 is rotated by the driving source while supplying the polishing liquid. The polishing carrier 10 is polished together with the crystal wafer 20 by revolving while rotating.

  According to the first embodiment, since the inner wall 12 of the storage hole 11 of the polishing carrier 10 is coated with the resin 13, the crystal wafer 20 is removed from the storage hole 11 when the crystal wafer 20 is polished by the double-side polishing machine 30. Since the received force can be relaxed by the resin 13, damage to the crystal wafer 20 can be suppressed. In addition, the resin ring as described in the background art is not mechanically engaged with the inner wall 12 of the storage hole 11, but the inner wall 12 of the storage hole 11 of the polishing carrier 10 is integrally covered with the liquid resin 13. Therefore, as compared with the structure in which the resin ring is fitted into the inner periphery of the storage hole, the present invention can be easily applied to the crystal wafer 20 that needs to be thinly finished.

  Next, an embodiment of a crystal wafer polishing method according to the present invention will be described as a polishing method of Embodiment 2 with reference to FIGS. FIG. 3 is a plan view showing steps on the polishing carrier side in the polishing method of the second embodiment. 4A and 4B are a perspective view and a plan view showing a process on the quartz wafer side in the polishing method of the second embodiment.

  In the polishing method according to the second embodiment, the crystal wafer 20 is stored in a state where the end surface 21 of the crystal wafer 20 is in contact with the inner wall 12 covered with the resin 13 by inserting the crystal wafer 20 into the storage hole 11 of the polishing carrier 10. The quartz wafer 20 is held by the holes 11 (FIG. 1) and the quartz wafer 20 is polished together with the polishing carrier 10 using a double-side polishing machine 30 (FIG. 2).

  Here, the end face 21 of the crystal wafer 20 may be covered with the resin 22 before the crystal wafer 20 is put into the accommodation hole 11 (FIG. 4). Alternatively, the crystal wafer 20 may be obtained by covering the crystal ingot 42 with the resin 22 and then cutting out the crystal wafer 20 to cover the end face 21 with the resin 22 (FIG. 4). Further, the inner wall 12 may be covered with the resin 13 by applying the resin 13 to the inner wall 12 after removing the irregularities on the inner wall 12 of the storage hole 11 (FIG. 3).

  Next, the process on the polishing carrier 10 side will be described in detail mainly based on FIG. First, as shown in FIG. 3A, the polishing carrier 10 before the inner wall 12 is coated with the resin 13 is prepared. The polishing carrier 10 is produced from a metal flat plate such as SK material (blue steel) by pressing or etching. Since unevenness such as burrs is likely to appear in the storage hole 11, it is desirable to remove the unevenness on the inner wall 12 with a file or the like before applying the resin 13.

  Subsequently, as shown in FIG. 3B, a resin 13 is applied to the entire polishing carrier 10. At this time, the resin 13 may be applied to at least the inner wall 12 instead of the entire polishing carrier 10. Moreover, in order to fully cover the unevenness | corrugation of the inner wall 12 with the resin 13, the convex protrusion of the inner wall 12 can be more coat | covered by apply | coating the resin 13 in multiple times, and damage to the crystal wafer 20 can be suppressed.

  Finally, as shown in FIG. 3C, both surfaces of the polishing carrier 10 are polished to remove excess resin 13, thereby completing the polishing carrier 10 in which the inner wall 12 of the storage hole 11 is covered with the resin 13. .

  Next, the process on the crystal wafer 20 side will be described in detail mainly based on FIG. First, as shown in FIG. 4 [A], a crystal block 41 is bonded together to form a large ingot 42 for cutting.

  Subsequently, as shown in FIG. 4B, the resin 22 is applied to the entire ingot 42. At this time, the resin 22 may be applied to at least the surface to be the end surface 21 of the crystal wafer 20 instead of the entire ingot 42.

  Finally, as shown in FIGS. 4C and 4D, the ingot 42 is cut with a wire saw (or blade saw), whereby the quartz wafer 20 whose end face 21 is covered with the resin 22 is completed.

  Here, specifications specific to the resin 22 on the quartz wafer 20 side will be described. In particular, when used in processes that require annealing, such as photolithography processes, the resin must have high heat resistance, a thermal decomposition temperature of 300 ° C. or higher, and a weight loss amount of 2% or less due to thermal decomposition at 300 ° C. Is desirable. Also, it has high chemical resistance so that it does not denature during the cutting process, polishing process, and polishing process. For example, it does not swell with water, and it is water-soluble such as oils such as kerosene and glycols that are used for cutting and cleaning. Desirably, the resin is resistant to oil.

  Specifications common to the resin 22 on the quartz wafer 20 side and the resin 13 on the polishing carrier 10 side are as follows. In order not to break (break) when subjected to resistance during processing, a resin that has high toughness at the time of curing and can provide a thin film that is as uniform and highly adhesive as possible when coated. Since it is difficult to evaluate the strength of the thin film, JISK5600-5-6, General test methods for paints-Part 5: Mechanical properties of the coating-Section 6: Test using adhesion (cross-cut method) Resins that meet Class 0 or Class 1 are preferred.

  When a single resin is not suitable for JISK5600-5-6, for example, a side chain with respect to the main chain of Si-O-Si such as polyorganosiloxane such as methyl group, methoxy group, ethyl group, ethoxy group, etc. A molecule having an organic functional group may be mixed with the resin. Alternatively, for example, a silane coupling agent may be applied before the resin coating to perform a silane coupling process.

  If the film thickness of the resin 13 or 22 is too thin, it cannot be applied uniformly, and if it is too thick, it is difficult to make the film thickness constant. In addition, if the film thickness is uneven, the outer dimensions change, causing problems such as the quartz wafer 20 not being able to enter the polishing carrier 10. In particular, when a resin, a raw material of the resin 22, such as a monomer, an oligomer, a prepolymer, and a curing agent are applied to the ingot 42, and the resin 22 is polymerized and cured by light or heat, the curing is caused when the film thickness is too thick. The film thickness is preferably not less than 50 μm and not more than 300 μm because it becomes non-uniform and the physical properties of the resin 22 are different for each part. The surface of the ingot 42 that coats the resin 22 is preferably rough considering the anchor effect of the resin 22. If a rough surface is sufficient, the number of steps for miniaturizing the surface of the ingot 42 is unnecessary, leading to a reduction in the number of steps.

  Next, the operation and effect of the polishing method of Embodiment 2 will be described.

  (1) According to the second embodiment, when the polishing carrier 10 is used, the force received by the crystal wafer 20 from the storage hole 11 when the crystal wafer 20 is polished by the double-side polishing machine 30 is relaxed by the resin 13. As a result, damage to the crystal wafer 20 can be suppressed.

  (2) When the end face 21 of the crystal wafer 20 is covered with the resin 22 before the crystal wafer 20 is inserted into the storage hole 11, the crystal wafer 20 is polished from the storage hole 11 when the crystal wafer 20 is polished by the double-side polishing machine 30. Since the force received by the wafer 20 can be relaxed by both the resin 13 and the resin 22, damage to the crystal wafer 20 can be further suppressed.

  (3) When the crystal wafer 20 is cut out after covering the crystal ingot 42 with the resin 22, the force received by the crystal wafer 20 at the time of cutting can be dispersed by the resin 22. Damage can also be suppressed.

  (4) By applying the resin 13 to the inner wall 12 a plurality of times, the convex protrusions of the inner wall 12 can be further covered, and damage to the crystal wafer 20 can be further suppressed. Further, when the resin 13 is applied to the inner wall 12 after removing the irregularities on the inner wall 12 of the storage hole 11, damage to the crystal wafer 20 can be further suppressed by covering the inner wall 12 with the resin 13 more reliably. .

  (5) In other words, in order to reduce damage caused by collision of the polishing carrier 10 with the crystal wafer 20, the polishing carrier 10 is formed by coating the inner wall 12 of the polishing carrier 10 with a resin 13 by coating or application, and covering the inner wall 12 with the resin 13. Is used for polishing or polishing the crystal wafer 20, it is possible to suppress breakage, chipping, scratches, scratches, etc. of the crystal wafer 20. Further, by coating the resin 22 on the surface of the ingot 42 (or block 41) before cutting and sealing it, even if a wire or the like damages the ingot 42 at the time of cutting and a crack or the like occurs, a larger chipping or crack Can be suppressed by the sealing effect of the resin 22. Further, by leaving the resin 22 coated before cutting as it is after cutting, the end surface 21 of the crystal wafer 20 is coated with the resin 22, so that resistance and friction during subsequent processing, Damage can be minimized (that is, the polishing carrier 10 and the crystal wafer 20 do not directly collide with the resin 22).

  As described above, the present invention has been described with reference to each of the above embodiments, but the present invention is not limited only to the configuration and operation of each of the above embodiments, and can be made by those skilled in the art within the scope of the present invention. Of course, it includes various variations and modifications that can be made. Further, the present invention includes a combination of some or all of the configurations of the above-described embodiments as appropriate.

DESCRIPTION OF SYMBOLS 10 Polishing carrier 11 Storage hole 12 Inner wall 13 Resin 14 Gear part 15 Passing hole 20 Crystal wafer 21 End surface 22 Resin 30 Double-side polisher 31 Sun gear 32 Internal gear 41 Block 42 Ingot

Claims (5)

Used when polishing a quartz wafer by a double-side polishing machine, in a polishing carrier having a storage hole for holding the quartz wafer,
The inner wall of the storage hole is coated with resin,
A polishing carrier for crystal wafers characterized by the above. The quartz wafer is inserted into the housing hole of the quartz wafer polishing carrier according to claim 1 so that an end surface of the quartz wafer is in contact with the inner wall covered with the resin. Hold and
Polishing the quartz wafer together with the polishing carrier using the double-side polishing machine,
A method for polishing a quartz wafer. Before putting the crystal wafer into the storage hole, the end face of the crystal wafer is covered with a resin,
The method for polishing a quartz wafer according to claim 2. Covering the crystal ingot with a resin and then cutting out the crystal wafer to obtain the crystal wafer with the end surface covered with the resin.
The method for polishing a quartz wafer according to claim 3. After removing irregularities on the inner wall of the storage hole, the inner wall is coated with the resin by applying the resin to the inner wall;
The method for polishing a quartz wafer according to any one of claims 2 to 4.

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