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From: rosentha@loki.Stanford.edu (Peter A. Rosenthal)
Newsgroups: sci.electronics
Subject: Re: Superconducting Interconnects
Message-ID: <1991Feb20.190601.20293@portia.Stanford.EDU>
Date: 20 Feb 91 19:06:01 GMT
References: <4450005@hpcc01.HP.COM>
Sender: news@portia.Stanford.EDU (Mr News)
Organization: Stanford University
Lines: 21

Superconducting interconnects allow some performance advantages
in certain applications.  For short on chip wiring, they are not 
particularly useful.  Aluminum can carry ample current, and the
power dissipated by the wiring is small compared to the
active device dissipation.  The device resistances and contact 
resistance dominate over the wiring resistance too, so the
rc time constants are not limited by the wiring.

	For connections greater than about 2 cm, the wiring
resistance of high quality aluminum does indeed limit the
performance both in terms of speed and dissipation of power.
For very large IC's and chip to chip interconnects one would
get a performance improvement by going to superconducting 
interconnects, but the problems of packaging ie. thermal expansion
mismatch and heatsinking become major headaches.

	High temperature superconductors will probably be
wedded to semiconducting IC's in the not to distant future but
substantial basic research and development must be done first.

			Peter Rosenthal


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