SEMICONDUCTOR DEVICE AND FABRICATION THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor device of SOI structure in which heat dissipation properties are enhanced while ensuring the breakdown strength and isolation performance. SOLUTION: A buried silicon oxide 2 is deposited by 2μm on a silicon substrate 1 and an N type silicon layer 3 is formed thereon. A trench 4 is made in the silicon layer 3 and deposited with a silicon oxide 5 on the inside thereof before being filled with a polysilicon 6. A high withstand voltage N-channel LMOS transistor Tr1 is fabricated in an insular silicon region 7. The buried silicon oxide 2 beneath a P-well region 9 is as thin as 0.1μm. A polysilicon 16 is deposited under a thin region 15 and the interval between the silicon substrate 1 and the insular silicon region 7 is made uniform.