Patent ID: 6713361
Filing Date: 2004-03-30
Classification: H01L

Abstract:
A method of forming a bipolar junction transistor structure, comprising:disposing a first oxide layer between a semiconductor substrate and a base polysilicon layer; forming a dielectric layer outwardly from the base polysilicon layer; forming an emitter region by removing a portion of the dielectric layer and a portion of the base polysilicon layer; removing a portion of the first oxide layer to form undercut regions adjacent the emitter region and to enlarge the emitter region; forming a second oxide layer on all surfaces of the undercut regions and outwardly from the semiconductor substrate in the emitter region; forming a second nitride layer on the second oxide layer; anisotropically etching the second nitride layer in the emitter region to expose a portion of the second oxide layer; and forming a third oxide layer outwardly from the portion of the second oxide layer in the emitter region.