| 摘要 |
PROBLEM TO BE SOLVED: To prevent threshold voltage of a low breakdown strength MOS transistor from varying and to form a channel diffusion layer and the source diffusion layer of an LDMOS transistor, while being self-aligning. SOLUTION: At an LDMOS transistor part, a field oxide film 24d is also formed in a drain-forming region and a channel-forming region, a channel diffusion layer 38 is formed using the field oxide film 24d as a mask, and then a source diffusion layer 40a is farmed using the field oxide film 24d as a mask. After removing the field oxide film 24d, the gate oxide film, gate electrode and source/drain of a low breakdown strength MOS transistor are formed.
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