Patent ID: 6287930
Filing Date: 2001-09-11
Classification: H01L

Abstract:
A method of forming a bipolar junction transistor, comprising the steps of:forming an electrically insulating masking layer as a composite of a first electrically insulating material layer and a second electrically insulating material layer on the first electrically insulating material layer, on a surface of a semiconductor substrate having an intrinsic collector region of first conductivity type therein;forming a trench that extends into the surface of the semiconductor substrate and into the intrinsic collector region, using the electrically insulating masking layer as an etching mask;selectively laterally etching the first electrically insulating material layer faster relative to the second electrically insulating material layer to define a lateral recess within the electrically insulating masking layer; thenforming a base electrode of second conductivity type that extends in said trench and in the lateral recess;forming a base region of second conductivity type that is self-aligned to a portion of said base electrode extending in the lateral recess and forms a P-N rectifying junction with said intrinsic collector region; andforming an emitter region of first conductivity type that forms a P-N rectifying junction with said base region.