| 摘要 |
PURPOSE:To suppress the generation of crystal defects effectively by a method wherein a buffer film is formed at the lower part of the second oxidation- resistant film to be formed on the side wall of the first oxidation-resistant film, and when a semiconductor substrate is oxidized, the stress generated when bird's beaks are grown is alleviated. CONSTITUTION:A pad silicon oxide film 12 is formed on the silicon substrate 11 on which an element forming region and a field oxide film will be formed. A silicon nitride film 13, which is the first oxidation-resistant film, is formed thereon, and besides, a silicon oxide film 14 is formed. A buffer film 10 is formed on the surface of the exposed silicon substrate 11. A thin silicon nitride film 15, which is the second oxidation-resistant film, is formed on the whole surface of the upper part and the like of the silicon oxide film 14. Then, a CVS silicon oxide film 16 is formed on the whole surface using a CVD method. A side wall 17 is formed by conducting a reactive ion-etching method leaving the stepped part only of the CVD silicon oxide film 16. Subsequently, the silicon nitride film 13, which is the first and the second oxidation-resistant film, and the silicon nitride film 15 having almost L-shaped cross-section are exposed. Then, an off-set field oxide film 18 is formed.
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