Alloy contact layer is made at relatively low temperature and has good wetting characteristics. Contacts adhere well to silicon carbide surface, penetrating about 300 to 500 angstroms into it. Contacts are ohmic on p-type silicon carbide and blocking on n-type

Shier, J. S.

English

NASA Technical Reports Server

4.	 November 1970
	 Brief 70-10445 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the National Technical Information Service, Springfield, 
Virginia 22151. Requests for individual copies or questions relating to the Tech Brief progam may be directed to the Tech-
nology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Aluminum—Silicon Eutectic Alloy Improves Electrical and Mechanical

Contact to Silicon Carbide 
The problem: 
To provide a reliable method for making electrical 
and mechanical contact to silicon carbide surfaces. 
The previous gold—tantalum alloys only make satis-
factory contact at relatively high (1200° to 1400°C) 
temperatures, are not reproducible, can separate due 
to a carbon layer at the interface, and are often block-
ing on p-type silicon carbide. 
The solution: 
A shallow aluminum—silicon eutectic alloy contact 
layer, made at relatively low temperature, with good 
wetting characteristics to give electrical and mechan-
ical reliability. 
How it's done: 
The contact alloy contains approximately 11.3 
atomic % silicon and 88.7 atomic % aluminum, and 
melts at 577°C. The alloy does not wet silicon carbide 
immediately upon melting, but must be raised to 
about 900°C before it flows out to form the contact. 
This wetting action proceeds slowly and affords ex-
cellent control of the wetted area. Contacts adhere 
well to the silicon carbide surface (see Note 1) and 
penetrate about 300 to 500A into the silicon carbide 
surface.
Notes: 
1. In 20 test contacts subjected to normal operation, 
none have come off. Additionally, efforts to me-
chanically push or pull them off with reasonable 
pressure have failed. 
2. These contacts are ohmic on p-type silicon carbide 
and are blocking on n-type. 
3. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space Administration 
Washington, D.C. 20546 
Reference: B70-10445 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: John S. Shier
Electronics Research Center 
(ERC- 10277) 
Category 03 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately ownedrights.
https://ntrs.nasa.gov/search.jsp?R=19700000429 2020-03-17T00:50:00+00:00Z


Aluminum-silicon eutectic alloy improves electrical and mechanical contact to silicon carbide

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server