| 摘要 |
PURPOSE:To independently design a peripheral circuit and a power element having high withstand voltage and large capacity in a power IC. CONSTITUTION:On an SOI substrate comprising a single crystal Si substrate 1b, an oxide film 20 and a single crystal Si substrate 1a, selective removal of the single crystal Si substrate 1a forms a stepped wall 8, on which a thick oxide film 8 is provided. On an active region not having the single crystal Si substrate 1a over it of the single crystal Si substrate 1b, a VDMOS 100 is formed and a MOS 101 having a thin oxide film 22 is formed on the single crystal Si substrate 1a, respectively. Thus thickness of the single crystal Si substrate 1a can be set according to a required thickness of the MOS 101. Since the oxide film 5 is thicker than the oxide film 22, it may not be damaged at the time of forming the M0S 101 and VDMOS 100.
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