Patent ID: 7923340

Claim:
A method of manufacturing a semiconductor device, comprising: forming openings in a first implant mask located over a bipolar region and a first non-bipolar region of a semiconductor substrate to expose a bipolar region portion and the first non-bipolar region; conducting a first implant through the openings to place a dopant in the semiconductor substrate to form tubs in the bipolar region portion and tubs in the first non-bipolar region; forming openings in a second implant mask located over the bipolar region portion and a second non-bipolar region to expose the tubs in the bipolar region portion and expose the second non-bipolar region, wherein the tubs of the bipolar region are collector contact tubs for bipolar transistors and the tubs of the first non-bipolar region being protected by the second implant mask; and conducting a second implant through the openings to place the dopant in the tubs in the bipolar region and form tubs in the second non-bipolar region, such that the dopant concentration in the tubs of the bipolar region is greater than the dopant concentration in the tubs of the second non-bipolar region.