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Encapsulated Mercury Contact For Semiconductor Dies

IP.com Disclosure Number: IPCOM000048991D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Ecker, ME: AUTHOR [+3]

Abstract

The disclosed compliant electrical interconnection structure between a semiconductor integrated circuit chip and a substrate permits a very high thermal expansivity mismatch. As a result, a larger chip may be joined to a substrate with very little reliability impact due to cyclic thermal excursion. When mercury contacts are employed to provide the compliant electrical interconnections, an encapsulating medium, such as oil, gel or other suitable fluid, may be used to contain the mercury and its vapors.

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Encapsulated Mercury Contact For Semiconductor Dies

The disclosed compliant electrical interconnection structure between a semiconductor integrated circuit chip and a substrate permits a very high thermal expansivity mismatch. As a result, a larger chip may be joined to a substrate with very little reliability impact due to cyclic thermal excursion. When mercury contacts are employed to provide the compliant electrical interconnections, an encapsulating medium, such as oil, gel or other suitable fluid, may be used to contain the mercury and its vapors.

In order to employ the mercury contact scheme, both the pads on the chip and ceramic module would have to be prepared so as to permit wetting by the mercury. Wettability and diffusion barrier effect is achieved by the deposition of gold, palladium, palladium/platinum and platinum to suitably prepared pad sites. A suitable amount of mercury is applied to the pads on the chip and on the substrate (ceramic). The chip pads are registered to the pads on the ceramic substrate and allowed to contact one another. The mercury, wetting both pad arrays forms small globules anchored to the chip and ceramic substrate. Located central to each edge of the chip is an L-shaped chip limiter' The L- shaped chip limiter is bonded to the ceramic substrate and limits the planar displacement of the chip. The portion of the L-shaped limiter that is located beneath the chip acts as a Z-axis limiter; i.e., it limits the compression of the mercury contact so as to avoid lateral bridging between adjacent contacts.

A further option to enhance cooling as well as anchor the chip in the desired position would be to have the back side of the chip and the corresponding area opposite the back of the chip similarly treated for mercury wetting. The introduction of a suitable amount of mercury between the back of the chip and protective cover would then form a liquid metal...