US 4,066,473 A · Method of fabricating high-gain transistors

Abstract

A method of fabricating bipolar transistors with increased gain. A base region is formed adjacent the collector (or emitter) region of the transistor, and a portion of the base region is then removed by etching. The emitter (or collector) is then formed by diffusing dopant into the base region where the portion has been removed, with the base region separating the emitter and collector having reduced thickness due to the etching. Advantageously, the base region may be formed with a more heavily-doped region overlying a less heavily-doped region, with a part of the more heavily-doped region removed by etching, thereby providing a highly conductive path to the lower conductivity base region separating the emitter and collector regions. The process steps are compatible with conventional integrated-circuit fabrication processes.

Claims12

Dependent claims

The method of fabricating a bipolar transistor with improved gain in a semiconductor body comprising the steps of:

forming a first region of one conductivity type in said semiconductor body,
forming a second region of opposite conductivity type overlying said first region and extending to a surface of said semiconductor body;
removing part of said second region;
and
diffusing a dopant of said one conductivity type into said second region where said part has been removed, thereby converting the net conductivity of a portion of said second region to said one conductivity type,
said first region of one conductivity type comprising the transistor collector, said second region of opposite conductivity type comprising the transistor base, and said portion of said second region having a net conductivity of said one conductivity type comprising the transistor emitter.

3 more elements

Dependencies are inferred from the claim text.

Method of fabricating high-gain transistors

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Method of fabricating high-gain transistors

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Abstract

Claims12