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Dual Base Lateral Bipolar Transistor

IP.com Disclosure Number: IPCOM000089011D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Bhattacharyya, A: AUTHOR [+2]

Abstract

In a lateral transistor, as shown in Fig. 1, the base 10 has two charge paths 12 and 14 between the emitter 16 and the collector 18. One of the two paths 12, 14 has a doping concentration, as much as 20 to 40 times higher than that of the other path. This transistor provides, e.g., an improved lateral PNP transistor performance at both high and low current with a single low dose/low energy ion implant without requiring additional masking and little, if any, impact on other elements of the structure.

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Dual Base Lateral Bipolar Transistor

In a lateral transistor, as shown in Fig. 1, the base 10 has two charge paths 12 and 14 between the emitter 16 and the collector 18. One of the two paths 12, 14 has a doping concentration, as much as 20 to 40 times higher than that of the other path. This transistor provides, e.g., an improved lateral PNP transistor performance at both high and low current with a single low dose/low energy ion implant without requiring additional masking and little, if any, impact on other elements of the structure.

The relationship between the alpha of a transistor and the collector current Ic with a doping concentration N(B) of 2x10/17//cc and with a doping concentration N(B) of 2x10/15//cc is indicated in Fig. 2 by curves A and B, respectively. The transistor produced when combining these characteristics is indicated by dotted curve C.

Curve A may be indicative of the doping concentration in charge path 12, and Curve B may be indicative of the doping concentration in path
14.

The transistor may be fabricated as follows:

1. Fabricate a conventional lateral PNP transistor with a low doped epitaxial layer.

2. Blanket ion implant arsenic or phosphorus at an appropriate step to increase the surface and subsurface concentration of the base 10 of the transistor with the peak concentration chosen so as to produce the resulting structure indicated in Fig. 1.

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