PURPOSE: To decrease a returning current without increasing an area of a collector region in a base region of a vertical transistor constituting I2L, by forming a part facing an injector shallower than the base region proper.

CONSTITUTION: In the base region 5 of the vertical transistor Tr1, the depth of the part 5a facing an emitter region 4 of a lateral transistor Tr2 constituting the injector is made to be shallow. Such a constitution can be formed by forming the base region 5 by diffusing the base, then forming an N+ type collector region, and implanting ions of P type impurities into the shallow region of the facing part 5a. Since the side 7 of the base facing the emitter region is formed in the shallow depth, the current returning to the injector from the base during the operation is reduced, and the amplification factor of the I2L is enhanced.