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Moat for Low Temperature Mercury Contact

IP.com Disclosure Number: IPCOM000047292D
Original Publication Date: 1983-Oct-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Caulfield, T: AUTHOR [+4]

Abstract

Providing a moat around a connector pad for a demountable mercury micropin contact increases the area of electrical contact and also increases the durability of the contact structure. Demountable mercury/pad connectors are very attractive for chip testing and package enhancement applications in Josephson technology. A major stumbling block in pursuing their use is their lack of durability against connect/disconnect and remercurize cycles. Mercury tends to dewet starting from the outer row of pads in any array, and this damage gradually moves inwards to inner rows, causing extensive dewetting within a few connect/disconnect cycles. The insulator layer window size is increased to form a moat 1 around contact 2, as shown in the figure. Moat 1 extends past interface metallurgy 3 and niobium contact 2 to silicon substrate 4.

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Moat for Low Temperature Mercury Contact

Providing a moat around a connector pad for a demountable mercury micropin contact increases the area of electrical contact and also increases the durability of the contact structure. Demountable mercury/pad connectors are very attractive for chip testing and package enhancement applications in Josephson technology. A major stumbling block in pursuing their use is their lack of durability against connect/disconnect and remercurize cycles. Mercury tends to dewet starting from the outer row of pads in any array, and this damage gradually moves inwards to inner rows, causing extensive dewetting within a few connect/disconnect cycles. The insulator layer window size is increased to form a moat 1 around contact 2, as shown in the figure. Moat 1 extends past interface metallurgy 3 and niobium contact 2 to silicon substrate 4. This provides a standoff around the pad, reducing the extent of mechanical damage occurring during the connect/disconnect cycles to the mercury amalgam layer which is responsible for mercury wetting. It is believed that this mechanical damage leads to an accelerated consumption of the freshly exposed interface metallurgy during subsequent remurcurizing operations, eventually resulting in mercury dewetting from the contact pads. Experiments with the insulator moat structure have shown that enhanced durability and reliable electrical contact are achieved.

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