JP2009000761A - Polishing sheet and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing sheet requiring a short period of time for rising up; to provide a manufacturing method of the polishing sheet. <P>SOLUTION: The polishing sheet made of a sheet-shaped foam element is characterized by its surface finished by carrying out buffing operations with abrasive having grain sizes of No.60-200 (60-200 meshes) as the final finishing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing sheet used when planarizing irregularities on a wafer surface by chemical mechanical polishing (hereinafter referred to as CMP) and a method for producing the polishing sheet.

  In recent years, miniaturization of wiring and multilayer wiring have been promoted for the purpose of increasing the density of semiconductor integrated circuits. Accordingly, a CMP process for flattening irregularities on the wafer surface has become important.

  A polishing sheet (polishing pad) is used in performing the CMP process. Various types of polishing sheets have been developed and put to practical use.

  However, polishing sheets that have been put to practical use so far are actually dressed up to form roughness using a dresser until they are actually usable after being attached to a polishing machine. Work was necessary.

For example, there has been proposed a method of grinding the surface of an abrasive sheet with sandpaper having a fineness of 400 or more (400 mesh or more) (Patent Document 1). It took a long dressing work after pasting.
JP 2004-98239 A

  An object of the present invention is to solve the above-described problems, and to provide an abrasive sheet that requires a short time to start-up and to provide a method for producing such an abrasive sheet.

  In view of the present situation as described above, the present inventors have conducted extensive research and found that the following polishing sheet can solve the above-described problems.

That is, the polishing sheet of the present invention has the following configuration (1).
(1) It consists of a sheet-like foam, and its surface is finished by buffing with an abrasive having an abrasive grain size of 60 to 200 (60 to 200 mesh) as the final finish. A polishing sheet to be used.

In addition, the polishing sheet of the present invention preferably has the following configuration (2) as a more specific configuration.
(2) The polishing sheet according to (1) above, wherein the foam-forming material is a polyurethane resin.

Moreover, the manufacturing method of the polishing sheet of this invention consists of the following structures (3).
(3) When manufacturing an abrasive sheet made of a sheet-like foam, as a final finish, an abrasive having an abrasive grain size of 60 to 200 (60 to 200 mesh) on the surface of the sheet-like foam. A method for producing an abrasive sheet, comprising buffing.

  According to the polishing sheet of the present invention, the so-called rise time required for preparation before use in actual use can be shortened.

  Further, according to the method for producing an abrasive sheet of the present invention, an abrasive sheet capable of shortening the so-called rise time required for preparation before use in actual use can be produced.

  Hereinafter, the polishing sheet of the present invention and the production method thereof will be described in more detail.

  The polishing sheet of the present invention comprises a sheet-like foam, and its surface is finished by buffing with an abrasive having an abrasive grain size of 60 to 200 (60 to 200 mesh) as the final finish. It is characterized by that.

  In the present invention, the foam that is a raw material of the polishing sheet is not particularly limited, but examples of the main forming material of the foam include polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, and halogen. Resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resin (polyethylene, polypropylene, etc.), epoxy resin, and photosensitive resin, etc. Can do. These may be used alone or in combination of two or more. Among these, the polyurethane resin is particularly preferable because it is a material that has excellent wear resistance and that can obtain a polymer having desired physical properties by variously changing the raw material composition.

  The polyurethane resin can be produced by applying a conventionally known urethanization technique such as a melting method or a solution method. However, with respect to the polyurethane foam of the present invention, pores (bubbles) are contained in the polyurethane. It is preferable to manufacture by the melting method in consideration of the necessity of taking in, cost, and working environment. Examples of the method for producing a polyurethane resin foam include, but are not limited to, a method of adding hollow beads, a method of forming a foam by a mechanical foaming method, a chemical foaming method, and the like.

  In the present invention, the method for producing the foam as the polishing sheet raw material is not particularly limited, and a general method can be used. For example, a prepolymer as a raw material for an abrasive sheet is placed in a reaction vessel, a curing agent is added, stirred, and then poured into a casting mold of a predetermined size to produce a block, and the block is formed into a bowl-shaped or band saw-shaped slicer A thin sheet may be formed in the method of slicing using the above, or in the casting step described above. Alternatively, the raw material resin may be dissolved and extruded from a T-die to directly obtain a sheet-like foam.

  In the present invention, the surface of the sheet-like foam obtained by such a method is subjected to buffing with an abrasive having an abrasive grain size of 60 to 200 (60 to 200 mesh). Preferably, it is 80-150. Particularly preferably, the final finishing is performed by buffing with an abrasive having an abrasive grain size of around 120 (120 mesh) (110 to 130).

  The buffing process of 60 to 200 (60 to 200 mesh) may be performed by grinding only 60 to 200 (60 to 200 mesh), or in the final stage after grinding with another count. Grinding may be used.

  It is preferable that the polishing surface in contact with the material to be polished of the polishing sheet of the present invention has a surface shape capable of holding and renewing the slurry during polishing. In order to efficiently maintain the slurry and renew the slurry, and to prevent destruction of the material to be polished due to adsorption with the material to be polished, it is preferable that the surface of the polishing sheet has an uneven structure. The concavo-convex structure may be any shape that is effective for holding and renewing the slurry, and is not particularly limited. For example, an XY lattice groove, a concentric circular groove, a through hole, or a non-through hole shape , Polygonal columnar grooves, cylindrical grooves, spiral grooves, eccentric circular grooves, radial grooves, and combinations of these grooves. In addition, these concavo-convex structures are generally regular, but in order to make slurry retention / renewability desirable, groove pitch, groove width, groove depth, etc. for each range. It is also possible to change.

  The polishing sheet of the present invention may have a single layer structure made of a sheet-like foam, or may be a laminated sheet polishing sheet obtained by laminating the single layer structure polishing sheet and a cushion sheet. Examples of means for attaching the single-layer structure polishing sheet and the cushion sheet include a method of sandwiching and pressing a double-sided adhesive tape between the polishing sheet and the cushion sheet.

  In the polishing sheet of the present invention, a double-sided adhesive tape may be provided on the surface to be bonded to the platen.

  Hereinafter, the configuration and effects of the present invention will be described based on specific examples. In addition, each evaluation item in an Example etc. was measured as follows.

(1) Measurement of average polishing rate and dressing time As a polishing apparatus, SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used, and the average polishing rate was measured using the prepared polishing sheet.
Using an 8-inch silicon wafer with a thermal oxide film of 1 μm, the initial average polishing rate is 1 minute using a polishing sheet before dressing, and the film thickness at 30 points in the wafer surface is measured. Calculated. Thereafter, using a diamond dresser (Asahi Diamond # 100 (counter)), dressing of the prepared abrasive sheet was performed for 1 minute under the conditions of a dresser rotation speed of 35 rpm, a polishing sheet rotation speed of 35 rpm, and a dresser load of 450 g / cm ² , The average polishing rate was calculated in the same manner as described above. This operation was repeated, and the cumulative dressing time when the average polishing rate was stabilized was measured.
An interference type film thickness measuring device (manufactured by Otsuka Electronics Co., Ltd.) was used for measuring the thickness of the oxide film. As the polishing conditions, silica slurry (SS12 Cabot) was added as a slurry at a flow rate of 150 ml / min during polishing. The polishing load was 350 g / cm ² , the polishing platen rotation speed was 35 rpm, and the wafer rotation speed was 30 rpm.

Example 1
100 parts by weight of a polyether prepolymer (Uniroy, Adiprene (registered trademark) L-325, isocyanate group concentration: 2.22 meq / g), and a filtered silicone nonionic surfactant (Toray Dow Silicone) , SH192) 3 parts by weight were mixed and the reaction temperature was adjusted to 80 ° C. Using a stirring blade, the mixture was vigorously stirred for about 4 minutes so that bubbles were taken into the reaction system at a rotation speed of 900 rpm. Thereto, it was melted in advance at a temperature of 120 ° C., and 26 parts by weight of 4,4′-methylenebis (o-chloroaniline) (Iharacamine (registered trademark) MT, manufactured by Ihara Chemical Co., Ltd.) was added. After stirring for about 1 minute, the reaction solution was poured into a pan-type open mold. When the reaction solution was no longer fluid, it was placed in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin foam block. The polyurethane resin foam block was sliced using a band saw type slicer (Fecken) to obtain a sheet-like polyurethane foam. The average thickness of the obtained polishing sheet was about 1.5 mm.

  A belt sander (made by Riken Corundum Co., Ltd., belt paper C54P) with 120 mesh abrasive particles attached to a buffing machine (made by Amitech), buffed both sides of the polyurethane sheet, and the thickness was about 1.40 mm. Next, a belt sander (Riken Corundum Co., Ltd., belt paper C54P) having 120 mesh abrasive grains attached thereto was attached to the same machine, and both surfaces of the polyurethane sheet were buffed again to a thickness of about 1.27 mm. The buffed polyurethane sheet was punched to a diameter of 61 cm, and concentric grooves with a groove width of 0.25 mm, a groove pitch of 1.50 mm, and a groove depth of 0.40 mm were formed on the surface using a groove processing machine. Using a laminator on the surface opposite to the grooved surface of this polyurethane sheet, a double-sided adhesive tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape) is affixed. Pasted together. Furthermore, a double-sided adhesive tape was bonded to the other side of the cushion sheet using a laminating machine to produce an abrasive sheet according to the present invention.

Comparative Example 1
In the same manner as in Example 1, a polyurethane foam sheet having an average thickness of about 1.5 mm was prepared. A belt sander (manufactured by Riken Corundum Co., Ltd., belt paper C54P) attached with 120 mesh abrasive grains was attached to a buffing machine (Amitech Co., Ltd.), and both surfaces of the polyurethane sheet were buffed to a thickness of about 1.35 mm. Next, a belt sander (Riken Corundum Co., Ltd., belt paper C54P) with 240 mesh abrasive grains was attached to the same machine, and both sides of the polyurethane sheet were buffed again to a thickness of about 1.3 mm. Further, a belt sander (Riken Corundum, manufactured by Riken Corundum Co., Ltd., belt paper C54P) having 400 mesh abrasive particles attached thereto was attached to the same machine, and both surfaces of the polyurethane sheet were buffed again to make the sheet thickness about 1.27 mm.

  Using a laminator on the opposite side of the grooved surface of this polyurethane sheet, a double-sided adhesive tape (Sekisui Chemical Co., Ltd., double tack tape) is applied, and then a cushion sheet is attached to the double-sided adhesive tape using a laminator. Pasted together. Further, a double-sided adhesive tape was bonded to the other surface of the cushion sheet using a laminator to prepare an abrasive sheet.

  Table 1 shows the cumulative dressing time and the average polishing rate after rising of the polishing sheets prepared in Example 1 and Comparative Example 1 described above.

  As can be seen from Table 1, in the polishing sheet of the present invention, the cumulative dressing time, which is the rise time, is greatly reduced.

  The polishing sheet according to the present invention can be used for polishing semiconductor substrates such as silicon wafers, optical members such as lenses, electronic materials such as magnetic heads and hard disks. In particular, it can be used favorably as a polishing sheet for polishing a semiconductor wafer as an object to be polished for the purpose of planarizing the semiconductor wafer by chemical mechanical polishing (CMP) technology.

  This polishing sheet requires less rise time, realizes shortening of preparation time and high-quality / high-quality polishing, and greatly contributes to improvement of productivity.

Claims (3)

  A polishing sheet comprising a sheet-like foam, the surface of which is finished by buffing with an abrasive having an abrasive grain size of 60 to 200 (60 to 200 mesh) as a final finish .   The polishing sheet according to claim 1, wherein the foam forming material is a polyurethane resin.   When producing an abrasive sheet made of a sheet-like foam, the final finish is buffed with an abrasive having an abrasive grain size of 60-200 (60-200 mesh) on the surface of the sheet-like foam. A method for producing an abrasive sheet, comprising: