JPS61260629A - Film for wafer processing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a film for preventing damage to wafers used when polishing wafers such as silicon wafers.

[Conventional technology]

Wafers used in the manufacture of semiconductor chips include materials such as silicon and gallium-arsenide, among which silicon is often used.For example, silicon wafers are made by thinning high-purity single crystal silicon to a thickness of about 500 to 1000 μ. Although they are manufactured by slicing, in recent years there has been a trend toward thinner chips as chips become smaller and more mass-produced. In addition, the size is 3 to 4 compared to the conventional size.
There is a shift from inches to 5 to 8 inches.

Silicon wafers themselves are inherently brittle, and in addition, those with integrated circuits built into their surfaces have the disadvantage that they are easily damaged by even the slightest external force due to the unevenness of the surface, and post-processing such as backside polishing is required. This has become a major obstacle.

Conventionally, as a method for preventing damage during surface processing of silicon wafers, a method has been adopted in which paraffin, resist ink, etc. are used to fill in the irregularities on the surface and perform post-processing while dispersing applied external forces. However, this method requires a step of drying and solidifying after applying paraffin, and further, cleaning and removing the paraffin using a solvent under heating after polishing, making the operation complicated. In addition, such conventional methods still cannot prevent wafer breakage when polishing large diameter wafers of 5 inches or more.
"Productivity" was the second major obstacle. Further, with the use of paraffin, etc., there is a problem of contamination of the wafer surface due to these, and there has been a strong demand for the development of a method for preventing damage to wafers as an alternative to the method of applying paraffin, etc.

[Problem that the invention seeks to solve]

In view of the above problems, it is an object of the present invention to prevent damage to wafers, preferably silicon wafers, and to contribute to improved productivity during polishing of wafers, and to process wafers without contaminating the wafer surface. The aim is to provide films for

[Means for solving problems]

The present inventors have developed a method for filling irregularities on the wafer surface and dispersing external forces by attaching a base film with special hardness to the wafer surface via an adhesive layer during polishing to prevent wafer damage. I found out what I can do. Furthermore, by laminating an auxiliary film having a specific hardness on the opposite side of the processed film to the adhesive layer,
The present inventors have discovered that the workability of attaching a wafer to a processed film and the workability of peeling off the film after polishing the wafer can be greatly improved without reducing the effect of preventing wafer damage, and have completed the present invention.

That is, in the present invention, an auxiliary film having a Shore D hardness of more than 40 is laminated on one surface of a base film having a Shore D hardness of 40 or less, and an adhesive layer is provided on the other surface of the base film. This is a film for processing wafers.

[Preferred mode for carrying out the invention]

The wafers to which the processing film of the present invention is applied are:
Not only silicon wafers but also gallium - arsenic, gallium -
Examples include wafers made of phosphorus, germanium, etc., and they are particularly suitable for use with large-diameter silicon wafers.

The base film used in the present invention includes thermoplastic resin,
Various films can be suitably selected as long as they are made of thermosetting resin, natural rubber, or synthetic rubber and have a Shore D hardness of 40 or less, preferably 30 or less. Shore D hardness is D according to ASTM D-2240.
This is a value measured using a model Shore hardness tester. Hardness is 4
If it exceeds 0, the ability to disperse the external force applied to the wafer is poor, and damage to the wafer during polishing cannot be substantially prevented.

Materials for the base film include thermoplastic elastomers such as ethylene-vinyl acetate copolymer, polybutadiene, polyurethane, soft vinyl chloride resin, polyolefin, polyester, and polyamide; and diene-based, nitrile-based, silicone-based, and acrylic-based materials. A typical example is synthetic rubber. The thickness of the base film is appropriately selected depending on the material, shape, surface condition, polishing method, and polishing conditions of the wafer to be protected, but is usually about 10 to 2000 μm.

- On the other hand, the auxiliary film may be made of paper, thin wood board, etc. laminated with thermoplastic resin, thermosetting resin, or synthetic resin. Films can be selected as appropriate. If the hardness is 40 or less, the purpose of laminating the auxiliary film cannot be achieved, and workability during lamination and peeling cannot be improved.

Materials for the auxiliary film include synthetic resins such as polyethylene, polypropylene, polyester, polyamide, hard vinyl chloride resin, polyethersulfone, polyacrylic, and phenolic resin, paper impregnated with phenolic resin, paper coated with polyethylene, etc. It is illustrated as a representative example.

The thickness of the auxiliary film is appropriately selected depending on the specifications of the machine that attaches the processing film to the wafer and the machine that peels it off, and the thickness of the base film.
A value of about 1000 is appropriate.

Methods for laminating the auxiliary film onto the base film include: ■ Applying adhesive to either the pre-manufactured base film or the auxiliary film and laminating them together, ■ Two-layer T-die or two-layer inflation. (3) A method of bonding by co-extrusion with T.
A method of laminating using the tie method or calendar method.

Various conventionally known lamination methods can be employed.

As the adhesive constituting the adhesive layer provided on the surface of the base film, common commercially available adhesives such as acrylic, ester, or urethane adhesives or synthetic rubber adhesives can be used. The thickness of the adhesive layer is determined appropriately depending on the material, shape, surface condition, polishing method, etc. of the wafer, but it is usually preferably about 2 to 2 0.0 μm.

As a method for laminating the adhesive on the surface of the base film, various conventional coating methods such as a roll coater method, a gravure roll method, a barcode method, a dipping method, a brush coating method, a spray method, etc. can be employed.

It can be applied to the entire surface or part of the base film.

The wafer processing film of the present invention is used for polishing the back surface of the wafer by bonding the wafer to the adhesive layer of the processing film during polishing T of the front surface of the wafer. By using a processing film in this manner, damage to the wafer during backside processing can be prevented. Further, after the processing is completed, the wafer is peeled off from the processing film and a simple cleaning operation is performed, thereby preventing contamination of the wafer surface.

〔Effect of the invention〕

The wafer processing film of the present invention has the property that the base film absorbs and disperses external force applied to the wafer, so if it is bonded to the wafer and the wafer surface is polished, the wafer will be Damage can be prevented. In addition, since the auxiliary film is laminated, it has excellent shape retention and is very easy to work with when bonding to wafers and peeling off after polishing.
It can also have a great effect on improving productivity.

〔Example〕

Example 1 An ethylene-vinyl acetate copolymer resin film (200 μs thick) with a Shore D hardness of 30 measured according to ASTM D-2240 and a polypropylene film (100 μs thick) with a Shore D hardness of 80 were prepared. The acrylic adhesive "Ponron" (manufactured by Mitsui Toatsu Chemical Co., Ltd.) is used to adhere and laminate the film, and the surface of the ethylene-vinyl acetate copolymer resin film is subjected to corona discharge treatment.
Aromatex" (manufactured by Mitsui Toatsu Chemical Co., Ltd.) was applied using a roll coater and dried to prepare a film for wafer processing provided with an acrylic adhesive layer of about 50 mm.

This film was laminated on the surface of a silicon wafer (6 inches) on which an integrated circuit was formed and the unevenness difference on the surface was approximately 50 μs using an automatic laminating machine manufactured by DISCO.
Polished with Disco Co., Ltd.). After polishing, the film was peeled off from the wafer, and the wafer was washed with pure water to produce 100 wafers with the back side processed. No wafers were damaged at this time, and the total working time was about 30 minutes.

Example 2 A two-layer film obtained by simultaneously forming butadiene rubber having a Shore D hardness of 20 and polypropylene having a Shore D hardness of 80 by a two-layer T-tie method (butadiene rubber layer thickness 200%, polypropylene rubber having a Shore D hardness of 80). Layer thickness 100Q
A silicon wafer processing film was prepared by applying an acrylic adhesive to a thickness of about 30 μm on the butadiene rubber side 1 of the film in the same manner as in Example 1. This film was attached to the surface of a silicon wafer with a surface roughness difference of about 30-
By the same method as in Example 1, 100 polished silicon wafers were manufactured. As a result, the number of damaged and defective products was O, and the entire processing work was completed in about 30 minutes.

Comparative Example 1 On the surface of the same silicon wafer used in Example 1,
100 processed silicon wafers were made by pouring resist ink at about 50°C, cooling it for 2 hours, polishing the back side of the wafer, washing the resist ink with trichlorethylene heated to 50°C, and then washing with pure water. was manufactured. The number of broken wafers at this time was 20.

The total time required for the rejection process was approximately 5 hours. That is, compared to Example 1, the production rate was about 1/10 and the product yield was 80%. Furthermore, contamination by resist ink was observed on the wafer surface after cleaning.

Comparative Example 2 A silicon wafer processing film was prepared by applying an acrylic adhesive to an ethylene-vinyl acetate copolymer resin film (thickness: 100 μs) having a Shore D hardness of 30 in the same manner as in Example 1.

This film was attached to the surface of the same silicon wafer as used in Example 1, and the back surfaces of 100 wafers were polished. As a result, the number of damaged wafers was O, but it took time to attach and peel the processing film to the wafer, and the total working time was about 1 hour, and the production speed was about 1 hour compared to Example 1. /2.

Comparative Example 3 A low-density polyethylene film (thickness 200u) having a Shore D hardness of 50 and a polypropylene film (thickness 1oop) having a Shore D hardness II of 80 were used in Example 1.
The films were laminated in the same manner as in Example 1, and an acrylic adhesive was applied to the surface of the low-density polyethylene film in the same manner as in Example 1 to prepare a silicon wafer processing film.

Using this film, the back surface of 100 silicone sheets was polished in the same manner as in Example 1. As a result, 76 defective products were produced due to damage.

Claims (1)

[Claims] 1) An auxiliary film having a Shore D hardness of more than 40 is laminated on one surface of a base film having a Shore D hardness of 40 or less, and an adhesive layer is provided on the other surface of the base film. A film for wafer processing.