Patent ID: 9312370
Filing Date: 2016-04-12
CPC Classification: H01L

Claim Text:
1. A method of forming an integrated circuit (IC) structure, the method comprising: a precursor structure on a substrate, wherein the precursor structure includes: a crystalline base layer, a first semiconductor layer positioned on the crystalline base layer, and a second semiconductor layer positioned on the first semiconductor layer; removing a portion of the substrate and the precursor structure to expose an underlying portion of the substrate beneath the precursor structure; forming a dielectric spacer on the precursor structure; selectively removing the first semiconductor layer, the second semiconductor layer, and the exposed portion of the substrate to undercut an exposed extrinsic base region of the crystalline base layer, wherein the selectively removing includes: growing the exposed extrinsic base region to have a greater thickness than an intrinsic base region of the crystalline base layer positioned between the substrate and the first semiconductor layer.