| 摘要 |
PROBLEM TO BE SOLVED: To control each carrier mobility individually in two or more kinds of MOS transistors formed on the same semiconductor substrate. SOLUTION: A channel region of two kinds of MOS transistors having gate oxide films of different thickness is formed in the main surface of a semiconductor substrate. Subsequently, roughness is formed on the surface of the semiconductor substrate by a first cleaning processing. After forming an oxide film on the surface of the semiconductor by a first oxidization and nitriding treated substrate, oxide films other than a predetermined region are removed so that a thick film of gate oxide may be formed. Subsequently, roughness is formed on the surface of the semiconductor substrate by a second cleaning processing. After forming an oxide film on the surface of the semiconductor substrate by a second oxidization and nitriding treatment, oxide films other than a predetermined region are removed so that a thin film of gate oxide may be formed. COPYRIGHT: (C)2007,JPO&INPIT
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