Browse Prior Art Database

Metal Subcollector Bipolar Transistor

IP.com Disclosure Number: IPCOM000089200D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Fowler, AB: AUTHOR

Abstract

Bipolar transistors are made with a diffused or otherwise highly doped subcollector (Fig. 1) which reduces the resistance from the collector junction to the contact. At present the surface resistance is at best > 10 ohms per square in practical devices.

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Metal Subcollector Bipolar Transistor

Bipolar transistors are made with a diffused or otherwise highly doped subcollector (Fig. 1) which reduces the resistance from the collector junction to the contact. At present the surface resistance is at best > 10 ohms per square in practical devices.

It is proposed to replace the heavily doped n/+/ layer with a metal film grown epitaxially on the substrate (Fig. 2). This can be accomplished by using molecular beam epitaxy or other suitable techniques. Silicon is grown on the metal layer epitaxially using the same technique of epitaxial growth of Si on W that has already been demonstrated. A very thin layer would allow extremely low sheet resistivities. Given a resistivity of 5 x 10/-6/ ohm/cm, a 500 angstroms layer of metal would result in 1 ohm per square.

An extension of this idea would be to use the metal as an additional level of metallurgy buried in the silicon.

It would be necessary that the first silicon deposited on top of the metal be heavily doped so as to act as an ohmic contact rather than a rectifier.

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