SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor device in which a VFET and elements of other types can be mounted mixedly on a semiconductor substrate without having a large level difference on the surface of a semiconductor layer laminated on the semiconductor substrate.

SOLUTION: On a P type semiconductor substrate 2, a box layer 3 of silicon oxide, an N+type lateral conductive layer 4 and an N-type surface layer 5 are laminated. On the box layer 3, a deep trench 6 having annular plan view is formed with a depth reaching the box layer 3 from the surface of the N-type surface layer 5. A transistor forming region 8 surrounded by the deep trench 6 and the box layer 3 is separated from the periphery thereof. In the transistor forming region 8, a source region 14 and a drain region 16 are formed in the surface layer portion of the N-type surface layer 5. Along the side face of the deep trench 6, the drain region 16 and an N+type vertical conductive layer 17 connected with the N+type lateral conductive layer 4 is formed.

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