Patent ID: 7615457
Filing Date: 2009-11-10
Classification: H01L

Abstract:
1. A method of making a bipolar transistor, comprising: defining a collector active region of single-crystal semiconductor material having a surface extending in a first lateral direction and a second lateral direction transverse to the first lateral direction; forming layered stack including a first dielectric region and a second dielectric region overlying the first dielectric region, each of the first and second dielectric regions overlying the collector active region; defining an opening extending through the first and second dielectric regions to expose a surface of the collector active region, the opening defining edges of the first and second dielectric regions, the edges being aligned in a vertical direction transverse to the first and second lateral directions; forming a frustum-shaped collector pedestal on the surface of the collector active region exposed within the opening, the collector pedestal having an edge referenced to the edge of the first dielectric region and having an upper surface, a lower surface, and a slanted sidewall extending between the upper surface and the lower surface, wherein the upper surface has an area substantially less than an area of the lower surface; forming an intrinsic base overlying all of the upper surface of the collector pedestal; forming an extrinsic base conductively connected to the intrinsic base; forming an emitter overlying the intrinsic base, the emitter having an edge referenced to the edge of the second dielectric region, such that the emitter is aligned with the collector pedestal in the vertical direction.