| 摘要 |
PROBLEM TO BE SOLVED: To provide a very reliable semiconductor device which has no occurrence of leakage current and malfunctions. SOLUTION: The semiconductor device is equipped with: an insulation layer 10b formed on a support substrate 10a; the first semiconductor layers 30 and 32 which are partially formed on the insulation layer 10b and have a high-withstand-voltage circuit 10HV; and the second semiconductor layers 34 and 36 which are formed in the first semiconductor layers 30 and 32 on the insulation layer 10b via an element isolation region 110b and have a low-withstand-voltage circuit 10LV partially formed in a P-type semiconductor layer 2 and in an upper layer of the P-type semiconductor layer 2. An upper part of the element isolation region 110b has a larger horizontal cross-sectional area with respect to the support substrate than a lower part thereof. The maximum area of a depletion layer which can be formed in contact with the lower part of the element isolation region is made smaller than the cross-sectional area of the upper part of the element isolation region. COPYRIGHT: (C)2009,JPO&INPIT
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