TRENCH ELEMENT SOLATION METHOD FOR SEMICONDUCTOR ELEMENT AND SEMICONDUCTOR ELEMENT USING THE SAME

PROBLEM TO BE SOLVED: To suppress occurrence of dents in a trench element isolation process by forming a trench etching mask pattern on a semiconductor substrate, forming over the entire surface of the semiconductor substrate, a dent-preventing film on the sidwall of the trench etching mask pattern, and depositing a liner layer on the dent-preventing film. SOLUTION: A part of a semiconductor substrate 100 is etched with a mask pattern 104 as a mask to form a trench 106, the inside wall of which is thermally oxidized to form an in-trench oxide film 108. A dent-preventing film 110 of a CVD oxide film with a film quality which has an etching selection ratio to a nitride film is deposited on the resulting object where the in-trench oxide film 108 is formed. After a liner layer 112 is formed using a nitride film, a high-temperature oxide film formed at such high temperature as 700-9000 deg.C is deposited, which is further treated with ammonia plasma processing.