JP2008093746A - Manufacturing method of plate-like body for holding polishing object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate-like body suitable for constituting a holding member of a polishing object hardly adhering to an upper panel of a polishing device or clogged with a polishing agent for reducing the defect of the polishing object due to a line trouble and achieving homogeneous polishing of the polishing object. <P>SOLUTION: When a sheet of thermosetting resin impregnated sheet fiber substrate or a plurality of the overlapped sheets are heated and pressurized between templates to mold the plate-like body, a sheet-like thin plate with thickness of 150 μm or less while having through-holes dotted therein is arranged at least on one side of the sheet fiber substrate to be heated and pressurized, thereby giving the shapes of the through-holes to the molded plate-like body. Preferably, the thickness of the sheet-like thin plate dotted with through-holes is 40-150 μm, and the numerical aperture is 1-60%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The manufacturing process of silicon wafers and hard disks includes a process of polishing these surfaces. The present invention relates to a method for producing a shaped plate-like body applied to a holding material for holding an object to be polished such as a silicon wafer or a hard disk in the polishing step.

  The object to be polished holding material has a structure in which one or a plurality of through holes for holding the object to be polished are formed in a disk having a driving gear around it. The object to be polished is fitted into the through hole, mounted on a polishing apparatus, and the holding material is driven in a plane to polish the object to be polished.

Conventionally, such an object holding material is constituted by a plate-like body obtained by processing a thermosetting resin laminate. The thermosetting resin laminate is a glass fiber woven fabric base epoxy resin laminate, an aramid fiber non-woven fabric base epoxy resin laminate, a cotton fabric base phenol resin laminate, or the like. Laminates for constituting the material to be polished are generally prepared by impregnating and drying a base material such as a glass fiber woven fabric, an aramid fiber nonwoven fabric or cotton cloth with a thermosetting resin containing no inorganic or organic particles. And one prepreg or a plurality of stacked prepregs are manufactured by heating and pressing.
These laminated plates are processed into a workpiece holding material as described above, and are used for polishing silicon wafers, hard disks and the like.

The polishing operation is performed by mounting the object to be polished on a polishing apparatus, holding the object to be polished in the through hole of the object to be polished, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), ceria (CeO). ₂ ) and the like, and an aqueous polishing liquid in which fine particles are dispersed is supplied.
The operation of detaching the workpiece holding material from the polishing apparatus, such as when replacing the workpiece holding material with a new one, is performed manually or by an automatic machine, but recently, it has been frequently performed by an automatic machine. I came. In addition, the removal of a polished object that has been polished and the supply of a new object to be polished have been increasingly performed by an automatic machine. Further, as a recent trend, colloidal silica having small abrasive particles has been frequently used conventionally, and it has become a situation in which the polishing holding material tends to adhere to the upper plate of the polishing apparatus.

  As described above, since the water-based polishing liquid is used for the polishing operation, the object holding material is in a state of being in close contact with the upper plate of the polishing apparatus. When the object to be polished is attached or detached and the object to be polished is taken out, the object to be polished is in close contact with the upper board and lifted together with the upper board, and the object to be polished may also be lifted together. Such a situation does not pose a major problem when manually attaching / detaching an object holding material or taking out / supplying an object to be polished, but it causes a line trouble when an automatic machine is used. .

As a countermeasure, when the thermosetting resin-impregnated sheet-like fiber base material is sandwiched between thermoplastic resin release films and molded by heating and pressing between mold plates, the thickness of the thermoplastic resin release film is set to 0.04 mm. A method for producing a plate-like body for a workpiece holding material in which a woven fabric is disposed between the release film and the template is proposed (Patent Document 1).
By heating and pressing as described above, the texture of the woven fabric is transferred to the surface of the plate-like body through the release film made of thermoplastic resin softened during the molding, Irregularities corresponding to the texture are given, and a temporary effect is recognized in preventing adhesion to the upper plate of the polishing apparatus. However, since the height of the provided unevenness is about 30 to 40 μm and the uneven shape of the unevenness is gentle, the abrasive (slurry) clogs the unevenness so that the abrasive does not circulate smoothly. There is a drawback that the polishing of the object to be polished becomes non-uniform.

JP 2004-314207 A

  The problem to be solved by the present invention is to provide a plate-like body suitable for constructing an object holding material that is difficult to adhere to the upper plate of the polishing apparatus and that is difficult to clog the abrasive, and is subject to line trouble. It is to reduce the defect of the polished object and achieve uniform polishing of the object to be polished.

  In order to solve the above-described problems, the method according to the present invention produces a plate-like body for an object holding material as follows. That is, in forming a plate-like body by heating and pressurizing one sheet-like fiber base impregnated with a thermosetting resin or a plurality of superposed sheets between mold plates, at least on one side of the sheet-like fiber base, A sheet-like thin plate having a thickness of 150 μm or less is disposed and heated and pressurized, and the shape of the through-hole is imparted to the molded plate-like body (claim 1). The sheet-like thin plate interspersed with the through holes preferably has a thickness of 40 to 150 μm (Claim 2) and a hole area ratio of 1 to 60% (Claim 3).

The hole pattern of the sheet-like thin plate is transferred to the surface of the plate-like body by heating and pressing as described above. The surface of the plate-like body is provided with irregularities corresponding to the opening portions of the sheet-like thin plate.
The height of the unevenness imparted to the surface of the plate-like body depends on the thickness of the sheet-like thin plate, and affects the durability of the effect of preventing adhesion to the upper plate of the polishing apparatus and the polishing uniformity of the object to be polished. . If the thickness of the sheet-like thin plate exceeds 150 μm, the height of the unevenness imparted to the surface of the plate-like body is too high, and the releasability of the release film after heat and pressure molding is deteriorated. Moreover, when releasing a release film, a release film may be torn. For this reason, the thickness of a sheet-like thin plate shall be 150 micrometers or less. Moreover, Preferably, the thickness of a sheet-like thin plate shall be 40-150 micrometers. By setting the thickness to 40 μm or more, the surface of the plate-like body can be provided with a sufficiently high unevenness, the durability of the effect of preventing adhesion to the upper plate of the polishing apparatus, and the uniformity of polishing of the object to be polished Becomes better.

Moreover, the area ratio of the unevenness | corrugation provided on the surface of a plate-shaped body is dependent on the aperture ratio of a sheet-like thin plate, and influences the contact | adherence prevention effect to the upper board of a grinding | polishing apparatus. The aperture ratio of the sheet-like thin plate is preferably 1 to 60%. Thereby, the convex part of sufficient area can be provided to the surface of a plate-shaped object, and the contact | adherence prevention effect to the upper board of a grinding | polishing apparatus becomes favorable. Here, the hole area ratio refers to the ratio of the area of the through hole in the unit area of the sheet-like thin plate. For example, in the case of a circular shape, the diameter of the through hole is measured to calculate the area, and the hole area ratio is calculated from the number of holes. In the case of a quadrangle, the area is calculated by measuring the lengths of the vertical and horizontal sides, and the hole area ratio is calculated from the number of holes.
If the size of the through hole is small, the irregularities are polished during polishing, and the effect of preventing adhesion to the upper plate of the polishing apparatus is reduced. Further, if the size of the through hole is large, the abrasive does not circulate smoothly, and the polishing of the object to be polished becomes uneven. Therefore, for example, φ0.3 to 30 mm is preferable in the case of a circle, and 0.3 × 0.3 to 30 × 30 mm in the case of a rectangle.

The plate-like body is processed into a predetermined shape to obtain a workpiece holding material, but the reason why the workpiece holding material having the unevenness on the surface layer is difficult to adhere to the upper plate of the polishing apparatus is as follows. It is considered as follows.
When the surface of the object to be polished is uneven, the area where the object to be polished is in contact with and in close contact with the polishing pad is smaller than when the surface is completely flat and smooth. It is considered that a very small amount of air gap exists between the polishing pad and the carrier. In addition, the strength of adhesion varies depending on the location of the unevenness and becomes non-uniform. Therefore, when the adhesion force is compared, the material to be polished having unevenness has a low adhesion force as a whole, and is easily peeled off from a portion having a low adhesion force, so that it is difficult to adhere to the upper plate of the polishing apparatus. It is.

Here, when the surface of the workpiece holding material is provided with irregularities on the upper surface, the opposite surface is a smooth surface without irregularities on the lower surface, and the workpiece holding material is attached to the polishing apparatus, Compared with the lower surface having a smooth surface, the adhesion force of the upper surface having irregularities is lowered, and the effect of preventing adhesion to the upper plate of the polishing apparatus becomes more remarkable. For this reason, it is preferable that the surface of the workpiece holding material to which the hole pattern of the sheet-like thin plate is transferred is only one side rather than both sides.
Also, the surface of the workpiece holding material is polished on the surface, and the surface of the workpiece is polished on the opposite surface, and the surface on which the surface roughness is given by a sheet-like thin plate having a larger porosity than the upper surface is used as the lower surface. When mounted on the apparatus, the adhesion force of the upper surface having a small convex area is lower than that of the lower surface having a large convex area, and the effect of preventing the adhesion of the polishing apparatus to the upper plate becomes more prominent. For this reason, it is preferable to arrange and form sheet-like thin plates having different opening patterns on the upper surface and the lower surface.

Further, the reason why uniform polishing can be obtained as compared with the case where the texture of the woven fabric is transferred is considered as follows.
In the case of a woven fabric, generally, wefts and warp yarns are alternately woven, and when transferred, the concave and convex shape of the irregularities is gentle, so that the slurry may stay without circulating smoothly. On the other hand, when a sheet-like thin plate interspersed with through-holes is transferred, the resin enters the opening portion to form a convex portion, and the other concave portions are flat and form a flat surface. Therefore, uniform polishing can be obtained by smoothly circulating the slurry through the flat portion of the recess.

  The method of providing unevenness on the surface of the workpiece holding material with the woven fabric of the prior art has an effect of preventing adhesion to the upper plate of the polishing apparatus, but the pitch of the unevenness is short and the uneven shape of the unevenness is gentle. The slurry does not circulate uniformly between the carrier and the pad, and uniform polishing is difficult to obtain.

  However, in the production method according to the present invention, the sheet-like fiber base material is produced by subjecting the sheet-like fiber base material impregnated with the thermosetting resin to heat-press molding to produce a plate-like body for a material to be polished. A sheet-like thin plate having a thickness of 150 μm or less and interspersed with through-holes is disposed on at least one side of the plate, and the shape of the through-hole is imparted to the molded plate-like body. It is difficult to provide a plate-like body that is difficult and that is suitable for constituting a workpiece holding material that performs uniform polishing.

In order to effectively prevent adhesion and obtain uniform polishing, it is necessary to control the height of the unevenness imparted by the sheet-like thin plate interspersed with through holes. The upper limit of the height of the unevenness is not particularly limited, but can be appropriately selected from the material and surface state of the polishing pad and the thickness of the object to be polished. Since the uneven height has a correlation with the thickness of the sheet-like thin plate, the thickness of the sheet is appropriately selected.
In addition, the effect of preventing pad adhesion depends not only on the height of the unevenness but also on the area ratio between the concave and convex portions. If the area of the portion that is in close contact with the pad is too large or too small, the effect of preventing adhesion cannot be obtained sufficiently, and can be appropriately selected in consideration of the effect of preventing adhesion. The area ratio of the unevenness has a correlation with the hole area ratio of the sheet-like thin plate (the area ratio of the hole area in the unit area), so the area ratio is appropriately selected.

As described above, in the production method according to the present invention, the sheet-like fiber is used for producing a plate-like body for a workpiece holding material by heat-pressing a sheet-like fiber base impregnated with a thermosetting resin. A sheet-like thin plate having a thickness of 150 μm or less and dotted with through holes is disposed on at least one side of the base material, and the shape of the through holes is imparted to the molded plate-like body.
The sheet-like fiber base material is not particularly limited as long as it is a sheet-like fiber base material that can constitute the material to be polished, such as a woven or non-woven fabric or cotton cloth of glass fiber or aramid fiber. However, the effect of preventing adhesion to the upper plate of the polishing apparatus is particularly remarkable for the workpiece holding material in which the organic fiber sheet fiber substrate is selected. Because, if the resin constituting the material to be polished is the same, the adhesion between the polishing apparatus upper plate and the material to be polished is almost the same regardless of the type of the sheet-like fiber base material, but the organic fiber sheet This is because an object holding material using a shaped substrate is relatively lightweight and is easily lifted together with the upper surface of the polishing apparatus.

  The thermosetting resin impregnated into the sheet-like fiber base material is not particularly limited, and may be phenol resin, epoxy resin, polyester, polyimide, or the like. However, thermosetting resins with relatively high heat resistance such as phenol resin and polyimide (for example, resins having a high density in the molecular skeleton such as a benzene nucleus), although the resin itself is hard Since the adhesiveness is relatively low, peeling of the interface between the base material and the resin is likely to occur during polishing, or the resin itself is liable to be destroyed or worn. For this reason, it is preferable to use an epoxy resin as the thermosetting resin.

  The material of the sheet-like thin plate interspersed with through-holes is only required to have heat resistance and strength that does not melt, deform or break during heat and pressure molding, and is made of metal (SUS, iron, etc.), plastic (Polyester, nylon, polypropylene, fluororesin, engineering plastic, etc.) are not particularly limited. As a method of providing an opening in a metal sheet-shaped thin plate, punching by a mold is common, and as a method of providing an opening in a plastic sheet-shaped thin plate, a punching by a die is used. And drilling with a heated needle. It is only necessary to make a hole in a predetermined regular shape, and it is not particularly limited. However, in the case of punching, a hole is generated by a heated needle because it may cause debris to remain on the film and have an adverse effect. Opening is preferred. Here, when the temperature of the heated needle is low, the insertion and removal of the needle does not go smoothly. Moreover, when the temperature of the heated needle is high, a through hole larger than a desired size is opened. For this reason, the melting temperature of the plastic sheet to be used is preferably + 10 ° C.

At the time of heat and pressure molding, a release film is disposed between the sheet-like fiber base material and the sheet-like thin plate interspersed with through holes. The release film to be used is not particularly limited as long as it is made of a material that can withstand the heat history during molding and can be released after molding. What is necessary is just to select from a polymethylpentene film, a fluororesin film, a polypropylene film, etc. according to a required degree of heat resistance.
The thickness of the release film is preferably 0.05 mm to 0.06 mm. When the release film thickness is reduced, irregularities are faithfully formed in the shape of the opening of the sheet-like thin plate, but there is a concern that it will be pulled and damaged by the irregularities of the opening of the sheet-like thin plate in contact therewith. Yes, as the release film thickness increases, the possibility of breakage decreases, but the shape of the opening of the sheet-like thin plate is absorbed by the release film, and it becomes difficult to provide unevenness to the plate-like body. is there.

The heating and pressing of the plate-like body can be performed between press hot plates. The thickness of the object to be polished varies depending on the polishing conditions such as the type and thickness of the object to be polished, and this is adjusted by changing the thickness of the sheet-like fiber substrate and the number of sheets to be overlapped. Unevenness can be imparted by disposing the release film, the sheet-like thin plate dotted with through-holes, and the template in this order on the outside of the sheet-like fiber substrate. During the heat and pressure molding, the melted resin enters the opening of the sheet-like thin plate through the release film, and the plate-like body forms a convex shape. Therefore, the uneven height can be controlled by the thickness of the sheet-like thin plate.
In addition, when arrange | positioning the sheet-like thin plate in which a through-hole is scattered on the outer side of a sheet-like fiber base material, you may interpose a release film between a sheet-like thin plate and a template. Thereby, the stain | pollution | contamination of the template after heat-press molding can be prevented.

The following were prepared as a sheet-like fiber base material.
(Aramid fiber nonwoven fabric substrate)
Para-aramid fiber (poly p-phenylene 3,4-diphenyl ether terephthalamide fiber) chop (fiber diameter: 1.5 denier, fiber length: 3 mm, Teijin's “Technola”) dispersed in water and made into paper This was sprayed with a water-soluble epoxy resin binder (glass transition temperature 110 ° C.), and heat dried to form a nonwoven fabric having a unit mass of 60 g / m ² . The blending mass ratio of para-aramid fiber / resin binder is 90/10.

The following were prepared as prepregs.
First, a bisphenol A type epoxy resin varnish containing dicyandiamide as a curing agent and 2-ethyl-4methylimidazole as a curing accelerator is prepared.
The aramid fiber nonwoven fabric substrate was impregnated with the varnish and dried by heating to obtain a prepreg. The amount of resin prepreg was adjusted so that the thickness when one of the prepregs was heated and pressed was 0.1 mm.

A polypropylene film (0.05 mm) was prepared as a release film, and the following were prepared as sheet-like thin plates dotted with through holes. Here, the shape of the through hole was circular, and the size was 3 mm.
Sheet-like thin plate A dotted with through-holes (thickness: 0.05 mm, polypropylene film, drilling method: drilling with a heating needle, aperture ratio 3%)
Sheet-like thin plate B interspersed with through-holes (thickness: 0.1 mm, SUS plate, drilling method: punching with a mold, opening rate 5%)
Sheet-like thin plate C interspersed with through-holes (thickness: 0.15 mm, SUS plate, drilling method: punching with a mold, opening rate 5%)
Sheet-like thin plate D interspersed with through-holes (thickness: 0.05 mm, polypropylene film, drilling method: drilling with a heating needle, aperture ratio 1%)
Sheet-like thin plate E interspersed with through holes (thickness: 0.05 mm, polypropylene film, drilling method: drilling with a heated needle, aperture ratio 60%)
Sheet-like thin plate F interspersed with through-holes (thickness: 0.3 mm, SUS plate, drilling method: punching with a mold, opening rate 5%)
Sheet-like thin plate G interspersed with through-holes (thickness: 0.025 mm, polypropylene film, drilling method: drilling with a heating needle, aperture ratio 3%)
Sheet-like thin plate H interspersed with through holes (thickness: 0.05 mm, polypropylene film, drilling method: drilling with a heating needle, aperture ratio 0.5%)
Sheet-like thin plate I interspersed with through-holes (thickness: 0.05 mm, polypropylene film, drilling method: drilling with a heating needle, aperture ratio 70%)
Example 1
A release film (thickness: 0.05 mm) is placed on both sides of 10 prepregs that are overlapped, and this is sandwiched between molds. At this time, the sheet-like thin plate A in which through holes are scattered is interposed between the release films on both sides and the template. This composition is put between the press hot plates, and a cushion material with a thickness of 10mm consisting of a kraft paper layer is placed between the hot plates and heat-pressed to obtain a 1.0mm thick laminate. It was.
This laminated board was processed into a workpiece holding material. This object to be polished is a disk having a diameter of 10 inches with a gear formed around it, and is provided with four through holes having a diameter of 3.5 inches for fitting the object to be polished.

Example 2
Instead of the sheet-like thin plate A dotted with through-holes, a sheet-like thin plate B dotted with through-holes was used, and the others were the same as in Example 1.

Example 3
Instead of the sheet-like thin plate A dotted with through-holes, a sheet-like thin plate C dotted with through-holes was used, and the others were the same as in Example 1.

Example 4
Instead of the sheet-like thin plate A dotted with through-holes, the sheet-like thin plate D dotted with through-holes was used, and the others were the same as in Example 1.

Example 5
Instead of the sheet-like thin plate A interspersed with through-holes, a sheet-like thin plate E interspersed with through-holes was used, and the others were the same as in Example 1.

Comparative Example 1
Instead of the sheet-like thin plate A dotted with through-holes, a sheet-like thin plate F dotted with through-holes was used, and the others were the same as in Example 1. However, the mold release property after molding was extremely poor, and the mold release Sometimes film tearing occurred, and the release film remained locally on the laminate, so that polishing evaluation could not be performed.

Example 6
Instead of the sheet-like thin plate A dotted with through-holes, a sheet-like thin plate G dotted with through-holes was used, and the others were the same as in Example 1.

Example 7
Instead of the sheet-like thin plate A dotted with through-holes, a sheet-like thin plate H dotted with through-holes was used, and the others were the same as in Example 1.

Example 8
Instead of the sheet-like thin plate A dotted with through-holes, a sheet-like thin plate I dotted with through-holes was used, and the others were the same as in Example 1.

Conventional Example 1
In Example 1, heat and pressure molding was performed with a mesh (0.4 mm thickness, polyester, 40 mesh) interposed between the release film and the template, and the others were the same as in Example 1.

Conventional example 2
In Example 1, heat and pressure molding was performed with a glass woven fabric (0.18 mm thick, manufactured by Nittobo, WEA-7628) interposed between the release film and the template, and the others were the same as in Example 1. did.

Polishing operations were performed using the workpiece holding materials in the above Examples, Comparative Examples, and Conventional Examples. The object to be polished is a 3.5 inch aluminum hard disk. Tables 2 and 3 show the results of evaluating the frequency of adhesion of the workpiece holding material to the upper plate of the polishing apparatus and the uniformity of polishing.
The surface roughness of the workpiece holding material was measured under the conditions shown in Table 1.
As an evaluation of the frequency of contact with the upper plate of the polishing apparatus, the number of times (the number of troubles) that the workpiece holding material was lifted in close contact with the upper plate of the polishing apparatus was evaluated. The number of troubles was determined by examining the number of times the workpiece was lifted in 1000 batches of polishing work (one batch was equipped with 5 workpiece holding materials and polishing 20 hard disks in a polishing machine). .
The uniformity of polishing was evaluated by the flatness of the hard disk (◯: good, Δ normal, x: inferior). Here, the flatness of the hard disk means a variation in surface roughness in one hard disk.

As is apparent from Tables 2 and 3, by applying the plate-like body manufactured by the method according to the present invention to the object to be polished, the object to be polished is closely attached to the upper plate of the polishing apparatus together. The effect of preventing the phenomenon of being lifted is obtained, and contributes to the uniformity of polishing.
As a result, the production yield of the object to be polished and the quality of the hard disk can be improved.

Claims (3)

In forming a plate-like body by heating and pressurizing one sheet-like fiber base material impregnated with a thermosetting resin or a plurality of superposed sheets between mold plates,
A sheet-like thin plate having a thickness of 150 μm or less and interspersed with through-holes is placed on at least one side of the sheet-like fiber base material, and heated and pressed to give the shape of the through-holes to the shaped plate-like body. A method for producing a plate-like body for an object-holding material.   The method for producing a plate for an object-holding material according to claim 1, wherein a thickness of the sheet-like thin plate interspersed with the through holes is 40 to 150 µm.   The method for producing a plate-like body for an object holding material according to claim 1, wherein the sheet-like thin plate interspersed with the through holes has a hole area ratio of 1 to 60%. .