| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device wherein LDMOS and MOS transistors can be mounted in a mixed state without damaging properties of the two transistors, and also to provide its manufacturing method. SOLUTION: After forming a field relaxation oxide film 17 in correspondence with a region on one side wherein a first gate electrode for LDMOS is scheduled to be formed, a first gate oxide film 13 and a first gate electrode 15a are formed (d). After forming a channel diffusion layer 11 self-alignedly with respect to the field relaxation oxide film 17 (e), an anti-oxidation film 53 is formed and then heat treatment is conducted to form a field oxide film 7 (f). After forming the second gate oxide film of the MOS transistor and then channel doping and formation of a second gate electrode are conducted, a first source highly-doped diffusion layer and a first drain highly-doped diffusion layer are formed self-alignedly with respect to the first gate electrode 15a and the field relaxation oxide film 17 in the LDMOS formation region, while a second source highly-doped diffusion layer and a second drain highly-doped diffusion layer are formed, with the second gate electrode in between, in the MOS transistor formation region. COPYRIGHT: (C)2005,JPO&NCIPI
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