Recycling method of silicon wafer

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

Currently, a silicon wafer is used as a base material for manufacturing various electronic parts, and a thin film is formed on the silicon wafer by CVD (Chemical Vapor Deposition) or PVD (Physical Vapor Deposition). This thin film is etched to form fine patterns, and various electronic parts are made.

【0002】

However, during the semiconductor manufacturing process, thin film formation and etching are repeated many times for patterning, so that defects always occur with a certain probability, and defective silicon wafers are discarded.

【0003】

Therefore, it is desired to efficiently regenerate the defective silicon wafer.

【0004】

The present invention relates to a method for regenerating a silicon wafer that has become a defective product.

[Conventional technology]

The thin film formed on the silicon wafer is Si0₂, SiC, Si₃N₄, GaAs, InP, Al, W, Ti, TiN, ITO, Al₂O₃Since various hardnesses such as those having various hardnesses are mixed and polishing is performed as it is to remove the thin film, the film is not uniformly polished. Therefore, the coating is removed to some extent by etching or the like before polishing. Further, as a method of removing the thin film by polishing, a rotary polishing machine was used to sequentially change from a coarse abrasive to a fine abrasive, and the thin film was removed by repeating polishing many times.

[Problems to be Solved by the Invention]

Recently, the size of silicon wafers has been increasing, and the polishing equipment has also been increasing in size accordingly. Therefore, if polishing is performed using a large number of polishing devices, the cost of the device becomes high, and the space of the device becomes large, resulting in an increase in cost. Since thin films of various hardness are mixed in order to perform efficient polishing, it is necessary to remove the film in advance to some extent by etching, etc., and this removal cost is also required, which increases the regeneration cost and makes it a new silicon wafer. There was a problem that the difference in cost did not appear so much.

[Means for solving problems]

As a means for solving the above problems, in the present invention, for example, a sandblasting apparatus is used, and as an abrasive, for example, alumina or silicon carbide having an average particle size of 20 μm or more and 5 μm or less is blown on a silicon wafer as a mixed fluid with compressed air. By attaching, the thin film on the silicon wafer was removed before the polishing process by the polishing machine, and then polishing was performed, so that the polishing time of the silicon wafer could be shortened and the regeneration cost could be suppressed.

BEST MODE FOR CARRYING OUT THE INVENTION

As a method for removing the thin film formed on the silicon wafer, an abrasive material having an average particle size of 20 μm or less and 5 μm or more was sprayed onto the silicon wafer using high-pressure compressed air using a sandblasting apparatus.

【0005】

The thin film is struck by spraying the abrasive on the silicon wafer, and the impact force lifts the film and removes the thin film on the silicon wafer. As the sandblasting device 1, a device as shown in FIG. 1 was used. A constant amount of the abrasive material is sent to the abrasive material hose 10 by the direct pressure type abrasive material quantitative supply device 8 and injected from the nozzle 5. The injected abrasive collides with the silicon wafer on the conveyor roller 16, removes large foreign matter from the lower part 12 of the hopper of the sandblasting device main body 1 through the separation tank 7, enters the cyclone 2, and can be used with the crushed abrasive. Only the abrasive material that can be separated into the material and the scraped dust and can be used enters the abrasive material tank 6, and the crushed abrasive material and the scraped dust flow to the dust collector 3 through the air pipe 11.

【0006】

The nozzle moves back and forth by the nozzle drive unit 15, and the processing substrate swings left and right by the roller conveyor 16 to perform processing. In this case, a direct pressure type sandblasting device is used, but a gravity type sandblasting device may be used.

【0007】

After that, the silicon wafer was wrapped using a polishing machine to regenerate the silicon wafer. Example 1 Si0 on a silicon wafer₂, W, Al₂O₃The substrate of an 8-inch silicon wafer with a thin film of TiN was sandblasted under the following conditions to remove the film. Sandblasting device ... HC-4XBARS-NH-401P (manufactured by Fuji Seisakusho) Abrasive used ... White Arundum # 1500 (alumina powder) Nozzle movement speed ... 30m / min Work movement speed ... 200mm / min Nozzle distance ... 30mm Compressed air pressure ... O.5kg / cm²Number of processing passes ... 2 passes Under the above processing conditions, the surface roughness after sandblasting was RmaxO.8 μm. After processing, wrapping was performed using silicon oxide having an average particle size of 0.5 μm using a polishing machine (manufactured by Speedfam).

[Simple explanation of drawings]

[Figure 1]

An example of a sandblasting apparatus used in the method of the present application [Explanation of symbols]

1 Sandblasting device body 2 cyclone 3 Dust collector 5 Sandblasting nozzle 6 Abrasive tank 7 Separation tank 8 Direct pressure type abrasive material quantitative supply device 10 Abrasive hose 11 Air duct 12 Under the hopper 15 Nozzle drive unit 16 conveyor rollers