PURPOSE: To remove reactive currents in an external base region by forming the base region in an I2L element by implanting p type impurity ions, forming an emitter region and a collector region by implanting n+ type ions while using a polycrystalline Si layer as a mask and shaping both in a self-alignment manner.

CONSTITUTION: An n+ type buried layer 2 is diffused and formed to the surface layer section of a p- type Si substrate 1, an n- type layer 3 is grown on the whole surface containing the buried layer 2 in an epitaxial manner, and a p- type region 10a as an injector and a p- type region 10b as an intrinsic base are formed by implanting B ions while using an SiO2 film 9 in a predetermined pattern as a mask. A polycrystalline Si layer 11 is deposited on the whole surface, B+ ions are implanted to the layer 11 and the layer 11 is given conductivity, and windows corresponding to collector and emitter forming regions are bored to the layer 11 while being positioned on the region 10b. Sections corresponding to the windows in an SiO2 film 12 generated at that time are removed, and coated newly with thin SiO2 films 14, and As+ ions are implanted through the films 14 to form n+ type emitter and collector regions 15.