Patent ID: 6060365
Filing Date: 2000-05-09
Classification: H01L

Abstract:
A method for fabricating a bipolar transistor, comprising the steps of:forming an oxide film with tapered ends on a semiconductor substrate in which a buried layer is formed;forming a floating poly base on the semiconductor substrate;forming an insulating film on the entire surface of the semiconductor substrate, including the floating poly base;selectively removing portions of the insulating film and the floating poly base to define a base region and a collector region;forming a first epitaxial layer having an upper surface in the base and collector regions, the first epitaxial layer having a thickness that is less than maximum thickness of the oxide film;forming a second epitaxial layer on the first epitaxial layer;implanting impurities into the second epitaxial layer in the base and collector regions;forming a second polysilicon layer on the second epitaxial layer in the base region; andforming electrodes on the semiconductor surface.