| 摘要 |
A nitride film (14A) as a had pattern mask in a peripheral transistor forming region and a cell transistor forming region is narrowed by A1 into a narrower nitride film (14B) by pull-back. While the narrower oxide film (14B) in the cell transistor forming region is covered by an oxide film (22), the narrower nitride film (14B) in the peripheral transistor forming region is further narrowed by A2 into a still narrower nitride film (14C) by pull-back. By making apertures (28A, 28B) in a buried oxide film (28) by using the narrower nitride film (14B) and the still narrower nitride film (14C), STI edges made of the buried oxide film (28) can be prevented from depressing or falling down.
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