Patent ID: 9653566
Date: 2017-05-16
CPC Classifications: H01L

Claim:
1. A device structure for a bipolar junction transistor formed using a substrate, the device structure comprising: a collector in the substrate; a trench isolation region in the substrate and coextensive with the collector; a base layer on the collector and on a first portion of the trench isolation region; and a first dielectric layer on the base layer and on a second portion of the trench isolation region peripheral to the base layer, wherein the trench isolation region includes an air gap located beneath the base layer and between the base layer and the collector, and the base layer includes a non-single crystal region, the first dielectric layer includes a plurality of openings extending through the first dielectric layer to the second portion of the trench isolation region, and the openings are positioned peripheral to the outer edge of the non-single crystal section of the base layer.