Oblique implantation in forming base of bipolar transistor

US5899723A · kind A · utility

Assignee

• NATIONAL SEMICONDUCTOR CORPORATION · US

Inventors

• Hung-Sheng Chen · San Jose, US
• Chih Sieh Teng · San Jose, US

Key dates

• Filing date: Feb 21, 1997
• Grant date: May 4, 1999
• Expiry date: Feb 21, 2017

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S438/965

Abstract

In fabricating a bipolar transistor, semiconductor dopant is introduced into a semiconductor body during a base doping operation to define a doped region, that forms a PN junction with adjoining semiconductor material and abuts a slanted sidewall of a field insulating region. The doped region constitutes a base region for the transistor. The base doping operation entails ion implanting the dopant into the body at a tilt angle of at least 15.degree. relative to the vertical. The minimum lateral base thickness and, the minimum sidewall base thickness increase relative to the minimum vertical base thickness. As a result, the magnitude of the collector-to-emitter breakdown voltage typically increases. The minimum lateral, sidewall, and vertical base thicknesses vary with the tilt angle and base-implant energy in such a manner that the minimum lateral base thickness and the minimum sidewall base thickness are separately controllable from the minimum vertical base thickness.