| 摘要 |
PURPOSE:To prevent transversal oxidation (a bird' s beak) from being generated, by using masks of bilayer films for selective oxidation so as to pile a CVD silicon nitride film on a heat silicon nitride film. CONSTITUTION:A heat silicon nitride film 2 is formed on a surface of a silicon substrate 1. Subsequently, a CVD method is used to pile a silicon nitride film 3 on the heat silicon nitride film 2. The heat silicon nitride film 2 and the silicon nitride film 3 on a part for the formation of a selective oxidation film are selectively etched to be patterned. This mask is used to perform oxidation and to form the selective oxidation film 4. Since such bilayer films composed of the heat silicon nitride film, good in its adhesiveness to the silicon substrate, and the silicon nitride film, high in its oxidation-proof performance are used as masks, the selective oxidation film can be formed with few birds beaks.
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