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Gettering Barrier

IP.com Disclosure Number: IPCOM000043351D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Brown, KH: AUTHOR [+4]

Abstract

Interconnection metallurgy for superconductive resistor trimming solder depositions, characterized by an AuIn2 layer as a gettering barrier between a titanium resistance layer and Pb/Au/In deposited in that sequence, are stable with Au/Ti resistors and have small contact resistance. In order for the Josephson logic devices to be able to operate properly with chip-to-chip variations in the values of junction critical currents and resistors, power supply resistor values must be held within limits or the resistor must be trimmed. The trim may be accomplished by fabricating shorting superconductive patches over portions of the resistors, the length of which shorting patches will be determined from the measurement of Im(0) and R variations in the wafer kerf sites.

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Gettering Barrier

Interconnection metallurgy for superconductive resistor trimming solder depositions, characterized by an AuIn2 layer as a gettering barrier between a titanium resistance layer and Pb/Au/In deposited in that sequence, are stable with Au/Ti resistors and have small contact resistance. In order for the Josephson logic devices to be able to operate properly with chip-to-chip variations in the values of junction critical currents and resistors, power supply resistor values must be held within limits or the resistor must be trimmed. The trim may be accomplished by fabricating shorting superconductive patches over portions of the resistors, the length of which shorting patches will be determined from the measurement of Im(0) and R variations in the wafer kerf sites. Solder alloys deposited in the sequence of PbAuPbIn have been suggested. PbAuPbIn metallurgy, however, does not form an electrically stable contact with Au/Ti resistors; the contact resistance gradually increases even during room- temperature storage from as-deposited values of 0.2N1.0 L to 1.0N3.5 L (per pair of 4 m wide R lines) over a period of 1N6 months. This is likely due to the fact that the titanium surface, after argon sputter cleaning, is still a very active getter even with the solder trim deposited on it. Some insulating layers are formed at the surface via fast mass transport through the soft Pb alloy films. AuIn2, used as the first layer in the deposition sequence of the Pb al...