PURPOSE: To flow large current through small area in a semiconductor device by collecting a number of triangular flat shapes each formed with a plurality of source and drain regions in one conductivity region when forming the source and drain regions.

CONSTITUTION: A number of reverse conductivity source and drain regions are diffused on one conductivity semiconductor substrate to thereby form a MOS transistor or the like. At this time the fundamental configuration of the source region 1 and the drain region are formed in triangular shape, and adjacently contacted each other through a gate region 3. A number of such triangular shapes are arranged regularly. When the same occupying area is formed at the triangular shapes thus formed, their channel width can be lengthened, and drain current may also be increased through the shapes to thereby increase the output of the transistor.