Method for making collector up bipolar transistors having reducing junction capacitance and increasing current gain

US5434091A · kind A · utility

Assignee

• TEXAS INSTRUMENTS INCORPORATED · US

Inventors

• Darrell G. Hill · Tempe, US
• Shou-Kong Fan · Richardson, US
• Ali Khatibzadeh · Plano, US

Key dates

• Filing date: Oct 7, 1994
• Grant date: Jul 18, 1995
• Expiry date: Oct 7, 2014

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S148/072

Abstract

This is a method of fabricating a bipolar transistor on a wafer. The method can comprise: forming a doped emitter contact layer 31 on a substrate 30; forming a doped emitter layer 32 on top of the emitter contact layer, the emitter layer doped same conductivity type as the emitter contact layer; forming a doped base epilayer 34 on top of the emitter layer, the base epilayer doped conductivity type opposite of the emitter layer; forming a doped collector epilayer 36, the collector epilayer doped conductivity type opposite of the base layer to form the bipolar transistor; forming an collector contact 38 on top of the collector layer; forming a base contact 40 on top of the base layer; forming a emitter contact 44 on top of the emitter contact layer; and selective etching the emitter layer to produce an undercut 45 beneath the base layer.