SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor device together with its manufacturing method where an electrostatic breakdown-strength is enhanced, even with an SOI-LDMOSFET having a relatively thick SOI film. SOLUTION: A layer 4a near an insulating layer 2 on the lower side of a P-type well region 4, which is not directly involved in device operation, is converted into a low-carrier generation layer, while the remaining P-type well layer 4b is utilized as an effective SOI layer. Thus the carrier generation amount is suppressed as a whole, resulting in enhanced electrostatic breakdown strength.