| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method with which a field-effect transistor having excellent efficient gate recess structure such as multistep recess structure without misaligning the mask, and which can be manufactured easily with excellent reproducibility. SOLUTION: An insulating thin film 100, which becomes an etching mask, is formed on an operating layer 111 on a semiconductor substrate 101 in a FET of multistage recess structure, and a photoresist film is formed thereon. A thin film aperture part 33 is formed on the thin film 100 by dry etching through the aperture part of the resist film, the first recessed part is formed on the operating layer 111 by wet etching through the thin aperture part 33, and it is used as the first recessed groove. Then, the thin film aperture part 33 is expanded in the lateral direction by wet etching, the second shallow recessed part 41 is formed on the operating layer 111 against the first recessed part by wet etching through the expanded thin film aperture part 34, and it is used as the second recessed groove.
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