Browse Prior Art Database

Hermetic Sealing of IC Chips

IP.com Disclosure Number: IPCOM000045779D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Marks, R: AUTHOR [+4]

Abstract

In the packaging art of connecting an integrated circuit (IC) chip to a substrate, one technique commonly used is wire bonding. In this technique an aluminum or gold wire is bonded to the top surface metallization, usually through vias formed in an overlying passivating layer, such as quartz. One problem with this technique is the susceptibility of such a connection to damage of the exposed metal by moisture in the ambient atmosphere. Encapsulation in a plastic is some help, but does not completely alleviate the problem.

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Hermetic Sealing of IC Chips

In the packaging art of connecting an integrated circuit (IC) chip to a substrate, one technique commonly used is wire bonding. In this technique an aluminum or gold wire is bonded to the top surface metallization, usually through vias formed in an overlying passivating layer, such as quartz. One problem with this technique is the susceptibility of such a connection to damage of the exposed metal by moisture in the ambient atmosphere. Encapsulation in a plastic is some help, but does not completely alleviate the problem.

The figure shows a technique of utilizing dual layer metallization in the vias formed in the overlying passivating layer. The figure shows an IC silicon chip 10, having an SiO(2) layer 12, with top surface metallization 14 thereover which connects with the devices (not shown) formed in the silicon. The metallization is preferably aluminum with a small amount of copper and, optionally, silicon as alloying elements.

A passivation layer 16 of quartz or other suitable material overlies the metallization 14, and is provided with vias 18 to allow access to the metallization 14 at selected locations. Hermetic sealing caps are provided in the vias 18, which are comprised of a layer 20 about 1000 Angstroms thick of chromium and an overlying aluminum layer 22 about 20,000 Angstroms thick. These caps can be vacuum-evaporated through a mask so that each one completely fills its respective via 18 and provides a hermetic seal to pr...