| 摘要 |
A gate electrode having a polymetal structure which is composed of polysilicon, tungsten nitride and tungsten is formed on a silicon substrate by RIE where a silicon nitride film is used as a mask. Thereafter, a silicon oxide film of about 3 nm is formed by selective oxidation, and a silicon nitride film of about 10 nm is formed by CVD. Moreover, the silicon nitride film is etched by using the silicon substrate as an etching stopper. Thereafter, a silicon oxide film of about 6 nm is formed again by thermal oxidation, and a silicon nitride film of about 20 nm is formed by CVD. Then, the silicon nitride film is etched by using the silicon oxide film as an etching stopper.
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