| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of processes of a semiconductor device including transistors of high withstand voltage and low withstand voltage of the same substrate. SOLUTION: A first semiconductor layer, a second semiconductor layer, and a third semiconductor layer are formed by forming a first element separation region 110a extending to an insulating layer, and a third element separation region 110b on a substrate 10 on which there are formed in order a support substrate 10a, the insulating layer 10b, and a semiconductor layer 10c. A second element separation region 210 not extending to the insulating layer is formed on the third semiconductor layer. There are formed a first high withstand voltage transistor 100P in the first semiconductor layer, a second high withstand voltage transistor 100N in the second semiconductor layer, and a first low withstand voltage transistor 200P in the third semiconductor layer and further a second low withstand voltage transistor 200N adjoining the first low withstand voltage transistor via the second element separation region. Low concentration impurity layers 50, 40 for the first and second high withstand voltage transistors 100P, N and wells 36, 34 of the low withstand voltage transistors are formed in the same process. COPYRIGHT: (C)2005,JPO&NCIPI
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