Patent ID: 8035196

Claim:
A bipolar transistor, comprising: a substrate; a silicon layer formed over the substrate, the silicon layer being doped with a first type of dopant, and wherein: a first implant process implants dopant of a second type opposite the first type in the silicon layer, the implanted dopant having a first dopant profile in the silicon layer; and a second implant process implants additional dopant of the second type in the silicon layer, the additional implanted dopant having a second dopant profile in the silicon layer different than the first dopant profile; an insulating layer formed by a thermal oxidation process that grows the insulating layer after doping the silicon layer by consuming a portion of the silicon layer and a portion of the dopant of the second type such that the concentration of the dopant of the second type is higher than the concentration of the dopant of the first type from an interface between the silicon layer and the insulating layer to a selected depth in the silicon layer, and wherein the concentration of the dopant of the second type is higher in the insulating layer than in the silicon layer.