Patent ID: 6271068
Filing Date: 2001-08-07
Classification: H01L

Abstract:
A method for making an emitter for a bipolar transistor on a BiCMOS circuit comprising the steps of:providing a substrate having partially completed BiCMOS structures and having completed buried subcollectors with reachthrough contacts and diffused base regions over said subcollectors for said bipolar transistors and forming emitters by;forming contact openings to said base regions;forming a stacked layer by depositing an undoped amorphous silicon layer and a polysilicon layer on said substrate and over said openings in a continuous deposition process step;doping said polysilicon layer;patterning said stacked layer to form polysilicon emitters over said openings;annealing said substrate to form shallow diffused emitter junctions in said substrate by diffusing the dopant in said polysilicon layer through said undoped amorphous silicon layer and into said substrate.