US 9,093,491 B2 · Bipolar junction transistors with reduced base-collector junction capacitance

Abstract

Fabrication methods, device structures, and design structures for a bipolar junction transistor. The device structure includes a collector region, an intrinsic base formed on the collector region, an emitter coupled with the intrinsic base and separated from the collector by the intrinsic base, and an isolation region extending through the intrinsic base to the collector region. The isolation region is formed with a first section having first sidewalls that extend through the intrinsic base and a second section with second sidewalls that extend into the collector region. The second sidewalls are inclined relative to the first sidewalls. The isolation region is positioned in a trench that is formed with first and second etching process in which the latter etches different crystallographic directions of a single-crystal semiconductor material at different etch rates.

Claims13

Dependent claims

A method of fabricating a bipolar junction transistor, the method comprising:

forming an isolation region surrounding a collector region in a substrate comprised of a first semiconductor material that is single crystal;
forming an intrinsic base layer on the collector region;
using a first etching process, forming a trench having a first section extending through the intrinsic base layer and a second section extending into the collector region, wherein the second section of the trench includes a plurality of sidewalls bordered by the collector region;
and
etching the collector region adjacent to the second section of the trench with a second etching process that etches different crystallographic directions of the first semiconductor material of the substrate at different etch rates,
wherein a section of the collector region is laterally positioned between the sidewalls of the second section of the trench and the isolation region.

3 more elements

Dependencies are inferred from the claim text.

Bipolar junction transistors with reduced base-collector junction capacitance

Life of this patent

Bipolar junction transistors with reduced base-collector junction capacitance

Life of this patent

Abstract

Claims13