PURPOSE: To operate the titled semiconductor device at higher frequency by forming a conductor or a semiconductor shaping a gate electrode while being adjoined to an insulator in the side section of a second semiconductor so that the upper end section of the gate electrode is not left on a third semiconductor.

CONSTITUTION: A first conductive film 2 is formed on an insulating substrate as a lower side electrode and a lead, and etched selectively (1). A P or N type conduction type first nonsingular crystal semiconductor 3 (S1), a second intrinsic or N or P type semiconductor 4 (S2) and a third semiconductor 5 having the same conduction type as the first semiconductor are laminated and formed on the upper surface of the conductive film 2. When a resist 18 is shaped on the upper surface and anisotropic etching from the vertical direction is executed, these conductors can also be left to sections except a region, in which there is the mask 18, as shown in broken lines 38, 38'. Consequently, a gate electrode can be formed selectively only to the periphery of the S1, S2 and S3 sides. There is no gate electrode in the upper section of the third semiconductor, the section 5 is removed by using a plasma etching method, and only 20, 20' in the side periphery of a projecting section are formed as gate electrodes.