| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for freely making layout of an underlayer pattern by a method, wherein after a polysilicon film is formed on the entire face of a semiconductor substrate having an undercut, a flat part of the polysilicon film is etched using a mixing gas as an etching gas, and also polysilicon in an undercut side part is etched and removed. SOLUTION: A first layer gate electrode 2 composed of polysilicon is formed on an underlayer insulation film 1 composed of a composite film through photolighography and dry-etching. A second layer polysilicon layer is formed thereon, and also a second layer gate electrode 4 is formed to form an interlayer insulating film 3 through thermal oxidation. Furthermore, a third layer polysilicon film 5, and a silicon oxide film 6 is formed thereon as an etching mask of the polysilicon film 5. Thereafter, a flat part of the polysilicon film 5 is etched using a mixing gas of a bromine compound gas, a chlorine gas, and an inert gas as an etching gas, and the polysilicon of the undercut side part is etched and removed.
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