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Protection of Copper Conductors in Multi-level Structures for Micro Electronic Packaging and Integrated Circuit Fabrication

IP.com Disclosure Number: IPCOM000110023D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Paunovic, M: AUTHOR

Abstract

Properties of copper conductors in an electronic package or integrated circuit structure can degrade during subsequent processing. For example, copper conductors can degrade during thermal curing of a dielectric used to separate layers of Cu conductors in a multi-level structure. In one example, when the dielectric is polyimide, copper reacts with polyamic acid to form a polyamic acid complex and during thermal curing this complex decomposes forming Cu2O (1). Particles of Cu2O degrade quality of the polyimide Cu interface and electrical properties of Cu conductors. One solution to this problem is Cu cladding.

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Protection of Copper Conductors in Multi-level Structures for Micro Electronic Packaging and Integrated Circuit Fabrication

       Properties of copper conductors in an electronic package
or integrated circuit structure can degrade during subsequent
processing.  For example, copper conductors can degrade during
thermal curing of a dielectric used to separate layers of Cu
conductors in a multi-level structure.  In one example, when the
dielectric is polyimide, copper reacts with polyamic acid to form a
polyamic acid complex and during thermal curing this complex
decomposes forming Cu2O (1).  Particles of Cu2O degrade quality of
the polyimide Cu interface and electrical properties of Cu
conductors.  One solution to this problem is Cu cladding.

      In Cu cladding the exposed Cu conductor surface is conformally
coated with a thin film of a corrosion-resistant metal or alloy.  A
metal M or alloy can be used for Cu cladding if it has the following
properties: (1) M has good adhesion to dielectric separating layers
of Cu conductors (e.g., polyimide) and to Cu conductors, (2) M does
not react with the dielectric, (3) interdiffusion between Cu and the
cladding material M is negligible; i.e., M is a good diffusion
barrier to Cu diffusion and there is no significant change in
electrical properties of Cu conductors due to diffusion of Minto Cu,
and (4) M has good corrosion resistance.  In the prior art (2,3) the
electroless Co(P) was used for Cu cladding.  However, Co(P) readily
corrodes in the presence of moisture.  Thus, because of its corrosion
properties Co(P) is not a desirable cladding material.  Another
material used in the prior art of copper cladding was electroless
Ni(P).  However, Ni(P) deposited from sulfate solutions is not a goo...