Method for fabricating BiCMOS transistor

Abstract

The present invention discloses a method for fabricating a BiCMOS transistor, which improves the high frequency characteristics of a bipolar transistor by reducing base resistance and a parasitic capacitance between the base and collector. The method comprises the steps of: forming a field oxide film for device isolation and a buried oxide film on a semiconductor substrate; forming a well where the MOS transistor is to be formed and a collector of a bipolar transistor on the semiconductor substrate; forming a gate insulating film on the semiconductor substrate; forming a gate electrode of the MOS transistor and an external base of the bipolar transistor on the gate insulating film; forming a nitride film for a spacer on the resultant material; removing the nitride film for the spacer in the bipolar transistor region; selectively forming a silicon layer and a polysilicon layer in the bipolar transistor region; forming an insulating film on the polysilicon layer; forming a spacer on the sides of the gate electrode of the MOS transistor and on the sides of the external base of the bipolar transistor; and forming a source/drain of the MOS transistor.

Dependencies are inferred from the claim text.