| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method or the like for preventing occurrence of roughness on the surface of a silicon nitride film, while obtaining a high selection ratio of the silicon nitride film to a silicon oxide film. SOLUTION: A polysilicon film 102, the silicon oxide film 103, and the silicon nitride film 104 are formed on a silicon substrate 101. Plasma etching is executed from that state. The silicon nitride film 104 is etched so as to leave the silicon nitride film 104 only around the polysilicon film 102. In an etching gas, at least a C<SB>m</SB>F<SB>n</SB>(m and n are respectively an integer of≥1) gas having a flow rate of≤10% of that of an O<SB>2</SB>gas is added to a mixed gas including a CH<SB>x</SB>F<SB>y</SB>(x and y are respectively an integer of≥1) gas and the O<SB>2</SB>gas. The etching gas is used for the plasma etching. COPYRIGHT: (C)2007,JPO&INPIT
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