Patent ID: 7615455
Filing Date: 2009-11-10
Classification: H01L

Abstract:
1. A method for manufacturing a bipolar transistor, the method comprising: coating a semiconductor substrate that includes a collector region with a layer of a first insulator and with a polysilicon layer; forming an opening extending through the polysilicon layer and extending only partially through the first insulator layer thereby eliminating at least a surface portion of the first insulator layer exposed by the opening; surrounding exposed surfaces of the polysilicon layer with a layer of a second insulator after forming an opening extending through the polysilicon layer and extending only partially through the first insulator layer, the lateral portions of the second insulator layer in the opening forming a spacer that has a lower spacer surface that is deeper than a lower surface of the polysilicon layer; eliminating a portion of the first insulator layer including the portion of the first insulator layer located beneath the opening and portions laterally beyond said opening thereby leaving in overhanging position a portion of the polysilicon layer; growing by selective epitaxy a base semiconductor layer on the collector region so that the base layer rises partially back along a substantially vertical central portion beyond the lower spacer surface in the opening of the first insulator layer in an installation under vacuum after formation of the spacer having the lower spacer surface that is deeper than the lower surface of the polysilicon layer; and depositing an emitter semiconductor layer under vacuum in the same installation with the vacuum maintained between the growth of the base semiconductor layer and the deposition of the emitter semiconductor layer.