JPH1133895A - Carrier material for holding article to be ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a hole end surface for fitting a carrier material gear part or an article to be ground from being worn out by forming a thermosetting resin in the surface of at least one side of a metal plate and reducing a friction force between the surface of the carrier material and a pad. SOLUTION: A thermosetting resin layer formed in a metal plate surface is made gradually thinner during grinding. If too thin from the beginning, the exposing time of the metal plate comes early and a friction force is increased. On the other hand, if the thermosetting resin layer is formed thick, even by adjusting the dry state of a thermosetting resin coated on a mold-releasing base material, the thermosetting resin is scratched because of the flow shortage of the resin during forming, or conversely, the flow of the resin in a peripheral part is considerable to make the peripheral part thin. The range of adjusting the drying degree (hardness) of the thermosetting resin is greatly narrowed, and control becomes difficult. Thus, the thickness of the thermosetting resin layer is preferably set in a range of 10 to 200 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In the production of semiconductor wafers such as silicon and germanium, liquid crystal display glass, hard disks, etc., there is a step of polishing these surfaces. The present invention relates to a carrier material for holding an object to be polished (an object to be polished) in a polishing step.

[0002]

2. Description of the Related Art A metal plate such as SK steel is used as a carrier material for holding the above various objects to be polished in a polishing step. For example, a carrier material of a silicon wafer has a gear that meshes with an internal gear and a sun gear of a polishing machine formed on a peripheral edge of a disc of SK steel, and a circular hole for fitting and holding the silicon wafer on a plate surface. Things. 2. Description of the Related Art In recent years, as the size of an object to be polished such as a silicon wafer and the number of objects to be polished held in one carrier material have increased, the area of the carrier material has increased. Thus, even if the area of the carrier material is increased, the polishing pressure per unit area does not change, so that the total pressing force needs to be increased. Further, in order to further increase the productivity, it is necessary to increase the polishing rotation speed.

[0003]

The increase in the area of the carrier material and the increase in the number of polishing revolutions increase the frictional force between the surface of the object to be polished and the surface of the carrier material and the polishing pad, etc., and impinge on the carrier gear portion. The load also increases. Along with this, there is a problem that the wear and damage of the gear portion become remarkable, and the life of the carrier material is shortened. Another problem is that metal carrier materials such as SK steel rust. Rust of the metal carrier material is caused by water at the time of polishing or water in the abrasive slurry, but rust is generated during temporary storage of the metal carrier material at the time of a process change (during a step change). This rust becomes foreign matter during polishing, and scratches (small scratches) occur on the surface of the object to be polished such as a silicon wafer. In addition, since the carrier material made of SK steel has a relatively large warp and twist, it is difficult to align the workpiece when setting the workpiece to the carrier material, or the workpiece to be polished between the carrier material and the polishing platen during polishing. There is a problem that a trouble may be caused by sneaking into a gap.

The first problem to be solved by the present invention is that
With respect to a metal carrier material for holding an object to be polished such as a semiconductor wafer, the frictional force with a polishing pad or the like is reduced to reduce wear of a gear portion and extend the life of the carrier material. It is also to suppress the generation of rust. A second problem to be solved by the present invention is to suppress warpage and twist by selecting stainless steel as the material of the carrier material, in addition to the first problem.

[0005]

In order to solve the above problems, a carrier material for holding an object to be polished according to the present invention comprises:
A thermosetting resin layer is formed on at least one surface of the metal plate. By forming the thermosetting resin layer on the surface, the frictional force between the carrier material and the polishing pad or the like is reduced, and the load on the gear portion of the carrier material is reduced. As a result, wear of the gear portion is reduced, and the life of the carrier material can be extended.

[0006] The coefficient of friction of a metal is determined by the hardness and shear strength of the metal, but the coefficient of friction of a polymer material such as a thermosetting resin decreases slightly with an increase in load. Furthermore, when the surface of the thermosetting resin layer becomes rough, the friction coefficient decreases. This is due to the formation of fine irregularities on the surface of the thermosetting resin layer with abrasive grains during polishing,
It means that the friction force does not increase, but rather decreases. In addition, it is generally said that a polymer has a higher speed dependency of frictional force than a metal. The coefficient of kinetic friction of the thermosetting resin layer tends to decrease as the speed increases, which is an effective configuration for avoiding an increase in frictional force accompanying an increase in the rotation speed of the polishing machine.

In addition, since the thermosetting resin layer is formed on the surface of the carrier material, rust generated during storage especially at the time of step change is remarkably reduced or eliminated. Scratch defects due to rust can be prevented, and the yield of the object to be polished is improved. The metal carrier material according to the present invention does not include a glass woven fabric or a glass component in the thermosetting resin layer. This is because, when the glass fibers fall off from the carrier material and enter the polishing system during polishing, there is a concern that scratches may be generated on the object to be polished such as a silicon wafer.

The metal material selected as the carrier material is S
There is no particular limitation as long as it can be used to hold the object to be polished, including K steel. The selection of stainless steel is the most preferable when comprehensively judged in consideration of the suppression of warpage and twist and the economic aspect.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The formation of a thermosetting resin layer on the surface of a carrier material is carried out by adhesion, and the surface of a metal plate may be subjected to a primer treatment or a coupling agent treatment in advance in order to increase the adhesion strength. It is also effective to increase the surface area by performing a physical roughening treatment such as sandblasting on the surface of the metal plate to increase the adhesive strength. The treatment for increasing the adhesive strength between the metal plate and the thermosetting resin layer is appropriately selected in consideration of the type of the thermosetting resin and the metal plate, the restriction of the process, the required performance and the economic aspect. The above-mentioned various treatments for increasing the adhesive strength may be omitted if there is no problem in the adhesiveness.

As the resin of the thermosetting resin layer formed on the surface of the metal plate, a phenol resin, an epoxy resin, a polyimide or the like is appropriately selected. Preferably, an epoxy resin is selected. Epoxy resin has a proven track record in polishing silicon wafers and the like as a carrier material composed of a glass woven fabric base epoxy resin laminate. It is also preferable to modify the epoxy resin by adding a flexible component such as a rubber component to reduce the brittleness of the resin. Selection of relatively heat-resistant resins such as phenolic resins and polyimides (resins having a high molecular skeleton such as benzene nuclei that do not directly participate in adhesion)
Since the resin itself is hard, but has relatively low adhesiveness to the metal plate, it is necessary to take into account the delamination of the interface between the metal plate and the thermosetting resin layer and the destruction of the thermosetting resin itself.

The method of bonding the thermosetting resin layer to the surface of the metal plate includes, specifically, three kinds of methods: lamination transfer, coating, and electrodeposition. The thickness of the thermosetting resin layer to be formed is preferably 10 to 200 μm. In order to industrially form a relatively thick thermosetting resin layer on the surface of a metal plate, a stack transfer method is preferable. The method of lamination transfer is as follows. First, a thermosetting resin such as an epoxy resin is applied to a release substrate (a resin film such as a polypropylene film or a metal foil such as an aluminum foil) and dried, and then a touch-dry state (B stage Semi-cured state). Next, the resin-coated surface of the releasable base material is overlaid on a metal plate having a predetermined size, and the resultant is charged into a laminating press and heated and pressed. After molding, the releasable base material is peeled off to obtain a metal plate having a thermosetting resin layer formed on the surface.

When a thermosetting resin layer having a thickness of more than 200 μm is formed by the method of lamination transfer, the drying state of the thermosetting resin applied to the release substrate is changed to a thin thermosetting resin layer. When the adjustment is made in the same manner as in the case of forming the sheet, the thickness of the sheet tends to be non-uniform because the absolute amount of the resin flow during molding is large.
Therefore, the drying state of the thermosetting resin applied to the release substrate is appropriately adjusted according to the thickness of the thermosetting resin layer to be formed. The thermosetting resin layer formed on the surface of the metal plate gradually becomes thinner during polishing. If it is too thin from the beginning, the metal surface is exposed early and the frictional force increases. On the other hand, when trying to form a thick thermosetting resin layer, even if the drying state of the thermosetting resin applied to the release substrate is adjusted, the thermosetting resin layer is blurred due to insufficient flow of the resin during molding. On the contrary, the flow of the resin in the peripheral portion is remarkable, and the thickness of the peripheral portion is reduced. The adjustment range of the degree of drying (curing degree) of the thermosetting resin is extremely narrow, and control becomes difficult. For these reasons, the thickness of the thermosetting resin layer is preferably from 10 to 200 μm. Even though a thermosetting resin layer is formed on the surface to reduce the frictional force, the gear portion of the carrier material naturally wears, and eventually reaches the end of its life. Since the natural wear of the gear portion of the carrier material is faster than the 200 μm thick resin layer is gradually thinned by polishing and the metal plate surface is exposed, a practical thermosetting resin layer thickness of 200 μm is sufficient. It is.

A carrier material for holding an object to be polished is required to have strict plate thickness accuracy and flatness. However, forming a thermosetting resin layer by coating ensures the surface flatness of the resin layer. Somewhat disadvantageous above. Further, formation of a thermosetting resin layer by electrodeposition is not suitable for forming a relatively thick thermosetting resin layer having a thickness of 10 to 200 μm which is preferable in the present invention. When simultaneously polishing both surfaces of the object to be polished held by the carrier material, a thermosetting resin layer is formed on both surfaces of the carrier material. When polishing only one surface of the object to be polished, a thermosetting resin layer may be formed only on one surface of the carrier material.

[0014]

EXAMPLES The following four types of metal plates were prepared. Metal plate (A): SK # 5 steel having a thickness of 0.6 mm Metal plate (B): Sand blasting of both surfaces of the metal plate (A) with 40 μm alumina particles Metal plate (C): Stainless steel having a thickness of 0.6 mm Metal plate (D): Both surfaces of metal plate (C) are sandblasted with 40 μm alumina particles Bisphenol A type epoxy resin is mixed with curing agent dicyandiamide and curing accelerator 2-ethyl-4-methylimidazole to form on metal plate surface An epoxy resin varnish for a thermosetting resin layer was prepared. The epoxy resin varnish was applied to one side of a 50 μm-thick polypropylene film and dried to prepare polypropylene films with various thicknesses of epoxy resin layers. Polypropylene film (A): 100 μm thickness after curing epoxy resin layer Polypropylene film (B): 5 μm thickness after curing epoxy resin layer Polypropylene film (C): 10 μm thickness after curing epoxy resin layer (D) : 200 μm thick epoxy resin layer after curing Polypropylene film (E): 250 μm thick epoxy resin layer after curing A phenol resin varnish was prepared, and the epoxy resin varnish was applied to one side of a 50 μm thick polypropylene film. After drying, a polypropylene film with a phenolic resin layer was prepared. Polypropylene film (F): 100 μm in thickness after curing of phenol resin layer Dimer acid-modified epoxy resin is mixed with the above epoxy resin varnish at a resin solid weight ratio of bisphenol A type epoxy resin / dimer acid modified epoxy resin = 80/20. Then, a low elasticity epoxy resin varnish was prepared. This varnish,
Coated on one side of a 50 μm thick polypropylene film
It dried and prepared the polypropylene film with a low elasticity epoxy resin layer. Polypropylene film (G): 100 μm thickness after curing of low elasticity epoxy resin layer Example 1 The surface of metal plate (A) is degreased with methanol, and the epoxy resin layer side of polypropylene film (A) is opposed to both surfaces. The metal plate (A) was integrally formed with an epoxy resin layer having a thickness of 100 μm on both sides of the metal plate (A). Thus, a 0.8 mm thick carrier material having both surfaces covered with the epoxy resin layer was obtained.

Example 2 A metal material (B) was used in place of the metal plate (A), and the other conditions were the same as in Example 1 to obtain a carrier material having a thickness of 0.8 mm.

Example 3 A metal material (C) was used in place of the metal plate (A), and the other conditions were the same as in Example 1 to obtain a carrier material having a thickness of 0.8 mm.

Example 4 A metal material (D) was used in place of the metal plate (A), and the other conditions were the same as in Example 1 to obtain a carrier material having a thickness of 0.8 mm.

Example 5 The thickness of the metal plate (D) was changed from 0.6 mm to 0.4 mm.
The surface is degreased with methanol, and the epoxy resin layer side of the polypropylene film (D) is disposed on both surfaces of the metal plate (D) with the epoxy resin layer facing each other. 2), an epoxy resin layer having a thickness of 200 μm was integrally formed on both surfaces. Thus, a 0.8 mm thick carrier material having both surfaces covered with the epoxy resin layer was obtained.

Example 6 The thickness of the metal plate (D) was changed from 0.6 mm to 0.8 mm.
The surface was degreased with methanol, and the epoxy resin layer side of the polypropylene film (C) was placed on both surfaces of the metal plate (D). ), An epoxy resin layer having a thickness of 10 μm was integrally formed on both surfaces. In this way, a carrier material having a thickness of substantially 0.8 mm and having both surfaces covered with the epoxy resin layer was obtained.

Example 7 A carrier material having a thickness of substantially 0.8 mm was obtained in the same manner as in Example 6 except that the polypropylene film (B) was used in place of the polypropylene film (C).

Example 8 The thickness of the metal plate (D) was changed from 0.6 mm to 0.3 mm.
The surface is degreased with methanol, and the epoxy resin layer side of the polypropylene film (E) is disposed on both surfaces of the metal plate (D). ), An epoxy resin layer having a thickness of 250 μm was integrally formed on both surfaces. Thus, a 0.8 mm thick carrier material having both surfaces covered with the epoxy resin layer was obtained.

Example 9 The surface of a metal plate (D) was degreased with methanol, and the phenolic resin layer side of a polypropylene film (F) was placed on both surfaces of the metal plate (D) so as to face each other. To form a phenol resin layer having a thickness of 100 μm on both sides of the metal plate (D). In this way,
A 0.8 mm thick carrier material having both surfaces coated with a phenol resin layer was obtained.

Example 10 The surface of a metal plate (D) was degreased with methanol, and the low elasticity epoxy resin layer side of a polypropylene film (G) was placed on both surfaces of the metal plate (D) so as to face each other. Heat-press molding between boards, 100μ thickness on both sides of metal plate (D)
m low elasticity epoxy resin layer was integrally formed. Thus, a 0.8 mm thick carrier material having both surfaces covered with the low elasticity epoxy resin layer was obtained.

Conventional Example The thickness of the metal plate (A) was 0.8 mm, and the carrier material was constituted only by the metal plate (A).

The silicon wafer was polished by using the carrier material of the above embodiment and the conventional example, and the performance of the carrier material such as the degree of wear of the carrier material gear portion and the scratch defect of the silicon wafer was evaluated. Table 1 shows the results.
Shown in The evaluation method and criteria are as follows. Appearance Visual evaluation ○: No abnormality △: Partial blurring Thickness accuracy Difference between maximum and minimum values Adhesive strength Pencil hardness test Abrasion Abrasion of the gear and the holding hole of the object to be polished was evaluated as 100 in the conventional example. Index (The larger the index, the smaller the wear) Economics ○: Low cost △: High cost

[0026]

[Table 1]

[0027]

As is clear from Table 1, the metal carrier material according to the present invention has a hole in which the gear portion of the carrier material and the object to be polished are fitted because the frictional force between the surface of the carrier material and the polishing pad is reduced. Wear of the end face can be suppressed, and the service life of the carrier material is extended. In addition, since rust does not occur during storage or is unlikely to rust, scratch defects of the object to be polished due to rust can be reduced. When stainless steel is selected as the metal material of the carrier material, the warpage and twist of the carrier material can be reduced, so that troubles such as crashes during polishing are avoided, and the quality of the object to be polished is stabilized and the product yield is improved. When epoxy resin is selected as the thermosetting resin layer,
It is more advantageous for suppressing the above-mentioned abrasion.
If it is set between 200 and 200 μm, the wear suppressing effect is large.
If a low-elasticity epoxy resin is selected, the effect of suppressing abrasion becomes more pronounced.

Claims (4)

[Claims] 1. A carrier material for holding an object to be polished, wherein a thermosetting resin layer is formed on at least one surface of a metal plate. 2. The carrier material for holding an object to be polished according to claim 1, wherein the metal plate is made of stainless steel. 3. The thermosetting resin layer has a thickness of 10 to 200 μm.
3. The carrier material for holding an object to be polished according to claim 1, wherein the carrier material is an epoxy resin layer. 4. The carrier material for holding an object to be polished according to claim 3, wherein the epoxy resin layer contains a flexible component.