A method for manufacturing a semiconductor device includes the steps of: forming an etching layer (17) formed of silicon on a semiconductor substrate (10); forming a mask layer (20) with a pattern on the etching layer (17), which includes an intermediate layer (22) as a silicon oxide film and a top layer (24) as a polysilicon; and etching the etching layer (17) using the mask layer (20) as a mask, and eliminating the top layer (24).