Semiconductor device having two different active elements whose partial

Abstract

A semiconductor device according to the present invention comprises a P-channel MOSFET having a gate, a source, and a drain, and a bipolar transistor having a collector, a base, and an emitter. The semiconductor device also includes an N.sup.- -type collector diffusion layer formed in an epitaxial layer on a P-type semiconductor substrate and adjacent to an N.sup.+ -type buried collector diffusion layer, and an N.sup.+ -type electrode lead-out region formed in contact with the N.sup.+ -type buried collector diffusion layer having an impurity concentration higher than the N.sup.- -type collector layer. A gate electrode section constituted by a gate oxide film and a gate electrode is formed on the N.sup.- -type collector layer and the N.sup.+ -type electrode lead-out region, and an P-type impurity is ion-implanted into the source region of the P-channel MOSFET and and an N-type impurity is doped into the emitter region of the bipolar transistor, with the gate electrode section being used as a mask. Furthermore, a P-type impurity is ion-implanted into a common area of the drain region of the P-channel MOSFET and the base region of the bipolar transistor and is diffused into the common area to a preset depth. Thus, the semiconductor device of bipolar-CMOS structure having a drain and base as the common area can be obtained.