New Method for Stripping Semiconductor Resists Uses Recycled Chemicals

On February 19, 2007, three Japanese companies, Toshiba Corp., Shibaura Mechatronics Corp. and Chlorine Engineers Corp., announced that they have jointly developed an innovative semiconductor resist stripping method that employs electrolyzed sulfuric acid. This is the first time that electrolyzed sulfuric acid has been applied to stripping resists.

A resist is a masking material used in the lithographic process of forming semiconductor circuits on a chip substrate. The resist must be removed once the circuits have been etched onto the substrate. The so-called wet process of resist stripping typically uses peroxymonosulfuric acid, a strong resist remover, conventionally produced by mixing sulfuric acid with hydrogen peroxide. In the new method, the peroxymonosulfuric acid is generated by electrolyzing sulfuric acid.

This new technology allows sulfuric acid to be recycled, and thus reduces the volume of sulfuric acid needed for the resist stripping process by about 70 percent, while totally eliminating the need for hydrogen peroxide. As a result, it reduces the overall environmental burden and improves the efficiency of wastewater treatment at semiconductor producing facilities. It also helps generate peroxymonosulfuric acid more efficiently, which contributes to shortening the resist stripping time by approximately 20 percent.

The new technology was introduced into the resist-stripping process at Toshiba's Yokkaichi Operations in April, 2007. It can be applied to the overall process of circuit formation on wafers, and the three companies intend to expand the range of its application.

http://www.toshiba.co.jp/about/press/2007_02/pr1901.htm

Posted: 2007/05/31 11:55:41 PM
Japanese version