Methods of counter-doping collector regions in bipolar transistors

摘要

The present invention provides a method of forming a bipolar transistor. The method includes doping a silicon layer with a first type of dopant and performing a first implant process to implant dopant of a second type opposite the first type in the silicon layer. The implanted dopant has a first dopant profile in the silicon layer. The method also includes performing a second implant process to implant additional dopant of the second type in the silicon layer. The additional implanted dopant has a second dopant profile in the silicon layer different than the first dopant profile. The method further includes growing an insulating layer formed over the silicon layer by consuming a portion of the silicon layer and the first type of dopant.