Patent ID: 6506655
Filing Date: 2003-01-14
Classification: H01L

Abstract:
A method of manufacturing a bipolar transistor in a semiconductor substrate of a first conductivity type, including the steps of depositing a first layer of polysilicon and doping the first layer with a dopant of the second conductivity type; depositing a second layer of silicon oxide; forming in the first layer and second layer an opening, and further including the steps of:annealing the substrate, first layer and second layer to form a third layer of oxide and to harden the second layer; implanting a dopant of the second conductivity type in the substrate; depositing a fourth layer of silicon nitride; depositing a fifth layer of silicon oxide and etching the fifth layer; anisotropically etching the fifth layer, fourth layer, and third layer; performing cleanings during which the fifth layer is reetched and takes a flared profile; depositing a sixth layer of polysilicon; and implanting a dopant of the first conductivity type in the sixth layer.