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Ti/Polyimide Contacts

IP.com Disclosure Number: IPCOM000037508D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bartha, JW: AUTHOR [+4]

Abstract

The use of polyimide in packaging technologies requires metallization layers on polyimide which give good metal/polyimide adhesion and at the same time low via resistance between the metal overlayer (which goes over the polyimide) and the metal layer underneath the polyimide. Metallurgies currently in development provide one or the other of these, but not both simultaneously: Cr gives excellent adhesion on polyimide but is susceptible to high via resistance due to its inability to dissolve or remove oxide, while Cu gives modest adhesion but can dissolve oxide at the via contact. The solution so far, as in MCP, has been to combine the two, using the high adhesion of Cr but achieving the low via resistance by keeping the Cr layer very thin so that low via resistance is achieved by the Cu.

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Ti/Polyimide Contacts

The use of polyimide in packaging technologies requires metallization layers on polyimide which give good metal/polyimide adhesion and at the same time low via resistance between the metal overlayer (which goes over the polyimide) and the metal layer underneath the polyimide. Metallurgies currently in development provide one or the other of these, but not both simultaneously: Cr gives excellent adhesion on polyimide but is susceptible to high via resistance due to its inability to dissolve or remove oxide, while Cu gives modest adhesion but can dissolve oxide at the via contact. The solution so far, as in MCP, has been to combine the two, using the high adhesion of Cr but achieving the low via resistance by keeping the Cr layer very thin so that low via resistance is achieved by the Cu. In these processes, the deposition is carried out at elevated temperature of the polyimide substrate, about 360oC.

The metal/polyimide interface in such cases becomes diffuse due to intermixing of metal and polymer across the initial interface. While this intermixing provides one mechanism to enhance the metal/polyimide adhesion, it also broadens the interfacial region into the polyimide layer and does not represent as inherently strong an adhesion mechanism as true chemical bonding between the metal and polyimide molecular chains.

Ti metallurgy provides a combination of characteristics which make it advantageous compared to Cu, Cr, and Ni. The chemical bondi...