Patent ID: 7422952
Filing Date: 2008-09-09
Classification: H01L

Abstract:
1. A method of forming a bipolar junction transistor in an epitaxial material, the epitaxial material having a top surface, a first conductivity type, and a dopant concentration, the method comprising: implanting a dopant into the epitaxial material to form a base region in the epitaxial material, the base region having a top surface that touches the top surface of the epitaxial material, a second conductivity type, a dopant concentration, and a depth measured normal to the top surface of the epitaxial material; implanting a dopant into the epitaxial material to form an emitter region in the base region, the emitter region having a top surface that touches the top surface of the base region, the first conductivity type, a dopant concentration that is greater than the dopant concentration of the epitaxial material, and a depth measured normal to the top surface of the epitaxial material; forming a sinker down region in the epitaxial material, the sinker down region having a top surface that touches the top surface of the epitaxial material, the first conductivity type, and a dopant concentration that is greater than the dopant concentration of the epitaxial material; and implanting a dopant into the epitaxial material to form a ballasting region in the epitaxial material, the ballasting region lying between the base region and the sinker down region, and having a top surface that touches the top surface of the epitaxial material, a conductivity type, a dopant concentration, and a depth measured normal to the top surface of the epitaxial material.