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Complementary NPN and PNP Transistors for Integrated Circuits

IP.com Disclosure Number: IPCOM000075681D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 96K

Publishing Venue

IBM

Related People

Chang, CS: AUTHOR [+4]

Abstract

For the design of integrated circuits, it is desirable to have both NPN and PNP transistors in the same substrate. The present method utilizes the fastest diffusant among elements in groups III and V in silicon, i. e. phosphorus, to convert, selectively, the P- substrate and/ or the P- epitaxial layer into N- type to fulfill several particular purposes. Three kinds of transistors are used. They are: A. The vertical NPN transistors in isolated pockets. They require P- substrate, N- epitaxial layer and are isolated from each other by the P isolation wall. B. The vertical PNP transistors in isolated pockets. : They require N- substrate, P- epitaxial layer, and are .- isolated from each other by the N-type isolation wall. : C. The vertical PNP transistors with collector diffusion isolation (CDI).

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Complementary NPN and PNP Transistors for Integrated Circuits

For the design of integrated circuits, it is desirable to have both NPN and PNP transistors in the same substrate. The present method utilizes the fastest diffusant among elements in groups III and V in silicon, i. e. phosphorus, to convert, selectively, the P- substrate and/ or the P- epitaxial layer into N- type to fulfill several particular purposes. Three kinds of transistors are used. They are:
A. The vertical NPN transistors in isolated pockets. They require P- substrate, N- epitaxial layer and are isolated from each other by the P isolation wall. B. The vertical PNP transistors in isolated pockets. : They require N- substrate, P- epitaxial layer, and are .- isolated from each other by the N-type isolation wall. :
C. The vertical PNP transistors with collector diffusion isolation (CDI). They require N- substrate, N- epitaxial layer and are self-isolated by the collector diffusion.

The methods of fabricating complementary transistors, both the combination of A and C and the combination of A and B, are as follows (note the numbers in the drawings show the steps that are being accomplished):

(Image Omitted)

Although only one NPN and one PNP, transistor is shown in the figures, it is desirable to use them in groups. One "N-epitaxial contact" (see Fig. B) is required for each group of CDI PNP transistors, if they are partitioned by the P- type isolation pockets.

A method of making the arsenic pedestal transistor with only one epitaxial layer deposition is also possible. The resulting device structure is similar to the double-epitaxial arsenic pedestal t...