High voltage SOI semiconductor device

摘要

In an SOI (Silicon-On-Insulator) semiconductor device (200), a first semiconductor layer (3) overlies a semiconductor substrate (1) so as to sandwich an insulating layer (2), and second (9) and third (11) semiconductor layers are formed on the surface of the first semiconductor layer (3). At the interface between the first semiconductor layer (3) and the insulating layer (2), a fourth semiconductor layer (12) with a conductivity type opposite that of the first semiconductor layer (3) is formed. The fourth semiconductor layer (12) includes an impurity density larger than 3x10 12 /cm 2 and equal to or less than 1x10 17 /cm 2 so as to be not completely depleted even when a reverse bias voltage is applied between the second (9) and third (11) semiconductor layers. The device has a source electrode (13) and a drain electrode (14).