JPH0618190B2 - Wafer processing film - Google Patents

Description

The present invention relates to a film for wafer processing. More specifically, the present invention relates to a wafer processing film capable of extremely effectively preventing damage to a wafer during polishing when polishing the back surface of a wafer such as a silicon wafer.

[Conventional technology]

Wafers used for manufacturing semiconductor chips include those such as silicon wafers and gallium-arsenic wafers, and among them, silicon wafers are widely used.

For example, a silicon wafer is manufactured by thinly slicing high-purity single crystal silicon to a thickness of about 500 to 1000 μm, but in recent years, with the downsizing and mass production of chips, there is a tendency toward further reduction in thickness. .

In addition, the size of the conventional 3-4 inches is 5
Moving to ~ 8 inches.

The silicon wafer itself is inherently fragile, and the one having an integrated circuit incorporated on its surface has the drawback that it is easily damaged by a slight external force due to the surface irregularities. In particular, during post-processing such as backside polishing, damage is likely to occur due to external force applied during processing, which is a major obstacle.

Conventionally, paraffin,
A method has been adopted in which a resist ink or the like is applied to fill the irregularities and to disperse and protect the external force applied to the wafer.

However, this method requires a step of applying paraffin, resist ink, etc., and further washing and removing the paraffin, resist ink, etc. applied after polishing with a solvent under heating, which complicates the operation, Takes a very long time, and the productivity is remarkably reduced. In addition to this, when polishing a large-diameter wafer of 5 inches or more, the damage to the wafer cannot be prevented yet, the yield becomes low, and it is a major obstacle in terms of productivity improvement. There is also a problem of contamination of the wafer surface due to the use of paraffin, resist ink, etc., and there is a strong demand for a wafer damage preventive measure that replaces such a coating method.

[Problems to be Solved by the Invention]

In view of the above points, an object of the present invention is to provide a method for preventing damage to a wafer during polishing of the wafer, contributing to improvement of productivity, and not contaminating the wafer surface. Is to provide.

[Means for Solving the Problems]

The inventors of the present invention have conducted extensive research to achieve the above object. As a result, instead of the above-mentioned conventional method of applying paraffin, resist ink, or the like, a film having a specific hardness, that is, a Shore D type hardness of 40 is obtained. When a film having an adhesive layer on a base film is attached to the wafer surface via the adhesive layer, the film fills irregularities on the wafer surface and disperses external force applied during wafer polishing. As a result, they have found that the damage of the wafer can be prevented very effectively, and have further studied to complete the present invention.

That is, the present invention relates to Shore D selected from an ethylene-vinyl acetate copolymer film and a polybutadiene film.
A film for wafer processing, characterized in that an adhesive layer having a thickness of 5 μm to 200 μm is provided on the surface of a base film having a mold hardness of 40 or less and a thickness of 10 μm to 2000 μm.

The wafer to be used for the wafer processing film of the present invention is not only a silicon wafer, but also a wafer of gallium-arsenic, gallium-phosphorus, germanium, gallium-arsenic-aluminum, etc., particularly a large-diameter silicon wafer. It is preferably used.

When the wafer processing film of the present invention is used for polishing a wafer, the wafer processing film is adhered to the wafer surface through the adhesive layer, and in that state, the back surface of the wafer to which the film is not adhered is polished. The method of processing is adopted.

In the present invention, it is important to use a film having a Shore D type hardness of 40 or less as the substrate film of the wafer processing film, and it is preferable to use a substrate film having a Shore D type hardness of 30 or less.

In the present invention using a base film having a Shore D type hardness of 40 or less, the external force applied to the wafer during the polishing process can be smoothly dispersed for the first time, whereby the damage of the wafer is extremely prevented. It can be achieved effectively.

On the other hand, even if the soft base film has a Shore D type hardness of more than 40, the external force is not smoothly dispersed during polishing, and an uneven external force is applied to the wafer. The damage cannot be substantially prevented, and the product yield and the like are significantly reduced.

The Shore D type hardness referred to here is ASTM D-224.
It is a value measured using a D-type Shore hardness tester according to 0.

As the base film having a Shore D type hardness of 40 or less, there is a film having a Shore D type hardness of 40 or less among films made of a thermoplastic resin, natural or synthetic rubber, and the like, for example, a Shore D type hardness of 40 or less. Thermoplastic elastomers such as ethylene-vinyl acetate copolymer, polybutadiene, polyurethane, soft vinyl chloride resin, polyolefin, polyester, polyamide, and diene-based, nitrile-based,
Films made of synthetic rubber such as silicone and acrylic can be used.

The present invention has a Shore D hardness of 40 among them.
The following ethylene-vinyl acetate copolymer film or polybutadiene film is used, and these two films usually contain a plasticizer, a metal compound stabilizer, etc., which are easily available and easily cause wafer contamination. It is suitable as a base film because it has no elasticity and it is easy to disperse external force during polishing.

The thickness of the base film is appropriately determined depending on the shape of the wafer to be protected, the surface condition, the polishing method, the polishing conditions, etc., but is usually 10 μm to 2000 μm.

For the pressure-sensitive adhesive layer provided on the surface of the base film, for example, a commercially available pressure-sensitive adhesive such as an acrylic-based, ester-based, urethane-based pressure-sensitive adhesive or a synthetic rubber-based pressure-sensitive adhesive is applied to the surface of the base film and dried. It is obtained by

The thickness of the pressure-sensitive adhesive layer is appropriately determined depending on the surface condition, shape, polishing method, etc. of the wafer, but is usually 5 μm to 200 μm.
μm is preferred.

As a method of applying the adhesive to the surface of the base film,
Conventionally known coating methods such as a roll coater method, a gravure roll method, a bar coating method, a dipping method, a brush coating method, and a spray method can be adopted, and the coating can be performed on the entire surface or a partial surface of the base film.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

In the following examples and comparative examples, the presence or absence of breakage of the wafer was visually observed, and when the wafer was broken into a plurality of pieces, when a part of the wafer was broken to cause a defect, the wafer was polished. When a crack was generated on the surface (back surface) or when the edge of the wafer was jagged, the edge was judged to be “damaged” and the number of damages was counted.

Example 1 One side of an ethylene-vinyl acetate copolymer resin film (200 μm thick) having a Shore D type hardness of 30 measured according to ASTM D-2240 was subjected to corona discharge treatment, and then the treated surface was subjected to acrylic treatment. An adhesive (manufactured by Mitsui Toatsu Chemicals, Inc., trade name: Aromatex) was applied by a roll coater machine and dried to prepare a film for wafer processing provided with an acrylic adhesive layer having a thickness of about 50 μm.

This film was attached to the surface of a silicon wafer (diameter: 6 inches, thickness: 600 μm) having a surface unevenness of about 50 μm, and the back surface of the wafer was polished by a polishing machine (manufactured by DISCO; rotary surface grinder DFG-83).
H / 6 type), and wafer feed speed: 200 mm /
Minute, grindstone grain size: 1st 40 / 60μm, 2nd 20 / 30μ
m, third 2/4 μm, cooling water: 5.0 / min, polishing amount:
Polishing was performed under the condition of 400 μm (600 → 200). Then, the film was peeled off and the wafer was washed with pure water.

The same polishing as above was performed on 100 silicon wafers. At this time, the number of damaged wafers was zero (0), and the working time required for polishing 100 silicon wafers was about 1 hour.

Example 2 For wafer processing in which a butadiene rubber sheet having a Shore D type hardness of 20 (thickness of about 300 μm) was used as a base film and an acrylic pressure-sensitive adhesive layer having a thickness of about 30 μm was provided in the same manner as in Example 1. I made a film. This was bonded to the surface of a silicon wafer having a surface irregularity difference of about 30 μm and polished in the same manner as in Example 1 to produce 100 polished silicon wafers. As a result, the number of defective defective products was 0, and the polishing operation of 100 silicon wafers was completed in about 1 hour.

Comparative Example 1 The same silicon wafer surface as that used in Example 1 was subjected to about 50 ° C.
After pouring and cooling the paraffin, the back surface was polished in the same manner as in Example 1, then the paraffin was washed and removed with trichlorethylene under heating at 50 ° C., and the surface of the wafer was washed with pure water by the conventional method. 100 polished silicon wafers were manufactured. The number of pieces damaged at this time is 0
However, the time required for all the steps from the injection of paraffin to the cleaning of the wafer for 100 silicon wafers was about 5 hours, and the production rate was about 1/5 of that of Example 1.
Was extremely low. Further, contamination with paraffin was observed on the surface of the wafer after cleaning.

Comparative Example 2 An acrylic pressure-sensitive adhesive coated film was prepared in the same manner as in Example 1 except that a low-density polyethylene film (200 μm thick) having a Shore D type hardness of 50 was used as the base film. Using this film, 100 silicon wafers were polished in the same manner as in Example 1.
As a result, 6 out of 100 defective products due to breakage occurred, and the yield was extremely low. The breakdown of the 6 defective products is as follows: 3 wafers were partially damaged to cause defects, 2 wafers had cracks, and 1 wafer had jagged edges. is there.

〔The invention's effect〕

The wafer processing film of the present invention in which an adhesive layer is provided on the surface of a base film made of an ethylene-vinyl acetate copolymer film having a Shore D type hardness of 40 or less or a polybutadiene film has high flexibility, It has the property of absorbing and dispersing external force. If this is attached to the front surface of the wafer and the back surface is polished, damage to the wafer during polishing can be prevented and it can be easily peeled off after polishing. The post-treatment is unnecessary, and the outstanding advantage that the contamination of the wafer surface is eliminated is exhibited.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-57-45929 (JP, A) JP-A-57-37836 (JP, A) JP-A-57-14043 (JP, A) JP-A-58- 145775 (JP, A)

Claims (1)

[Claims] 1. An adhesive having a thickness of 5 .mu.m to 200 .mu.m on the surface of a base film having a Shore D type hardness of 40 or less and a thickness of 10 .mu.m to 2000 .mu.m selected from ethylene-vinyl acetate copolymer film and polybutadiene film. A film for wafer processing, characterized by comprising layers.