Dielectric insulation type semiconductor integrated circuit having low withstand voltage devices and high withstand voltage devices

摘要

At the bottom of an island region in which a low withstand voltage transistor is formed, is provided a high concentration region of the same conductivity type as the island region having a larger thickness than a high concentration region provided at the bottom of an island region in which a high withstand voltage transistor is formed, and the bottom surfaces and side surfaces of the respective island regions are fixedly secured to a polycrystalline semiconductor layer via insulator films.