| 摘要 |
PURPOSE: A method for fabricating an element isolating film of a semiconductor device is provided to prevent an element isolating oxide layer from damaging and to allow trench edges to be smooth by treating upper and lower edges of the trench with a hydrogen heat treatment. CONSTITUTION: A pad oxide layer(2), a pad nitrated film(3) and a first oxide layer(4) are sequentially formed on a silicon substrate(1). Then, an isolating mask pattern is formed by etching the first oxide layer(4), the pad oxide layer(2), and the pad nitrated film(3). After that, a second oxide layer(5) is formed thereon and an oxide layer spacer(5A) is provided at a side wall of the isolating mask pattern by etching the second oxide layer(5). By using the first oxide layer(4) and the oxide layer spacer(5A) as an etching mask, a trench(t) is formed on the silicon substrate(1). Edges of the trench(t) are exposed by removing the oxide layer spacer(5A) and are made to be smooth by the heat treatment in the hydrogen atmosphere. Finally, an isolating film is formed by inputting the oxide layers(4,5) into the trench(t).
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