| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor and manufacturing method thereof capable of maintaining good characteristics in each transistor even when a plurality of kinds of transistors with different gate-oxide-film thicknesses are formed on one chip. SOLUTION: A first time of thermal oxidation treatment is carried out to form a first gate-oxide-film 107 (film thickness of 45Å) in regions A, B respectively. After a first polysilicon film 19 is formed, the first polysilicon film 19 in the region B is removed by etching to expose the first gate-oxide-film 107 in the region B. When a second time of thermal oxidation treatment is carried out, the first gate-oxide-film 107 (film thickness of 45Å) existing in an active region 5 is grown to increase its film thickness to be a second gate-oxide-film 21 (film thickness of 90Å). The first gate-oxide-film 107 is formed in the region A, and the second gate-oxide-film 21 is formed in the region B.
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