Patent ID: 7517768
Filing Date: 2009-04-14
Classification: H01L

Abstract:
1. A method of fabricating a bipolar transistor comprising: placing a substrate in a reactor chamber; forming a collector region into said substrate; forming a device isolation field comprising silicon oxide; forming nitride regions over the substrate; introducing a silicon source gas into said reactor chamber to form a silicon seed layer over an area on said collector region, device isolation field and said nitride regions, said reactor chamber having a pressure between 10-30 Torr and a temperature between about 700° C. and 850° C. and stopping said silicon source gas after said silicon seed layer is formed; simultaneously adjusting said reactor chamber to a pressure between about 70 Torr and 90 Torr and a temperature between about 600° C. and about 650° C. , and introducing said silicon source gas, a germanium source gas, and a carbon source gas into said reactor chamber to form a SiGe:C film over said silicon seed layer, said SiGe:C film being graded with a concentration up to 35% and with carbons forming into substitution sites in the SiGe:C film; wherein said silicon seed layer and said SiGe:C film form a base region; and forming an emitter over an area of said SiGe:C film.