The requirement for improved electrical performance and reducedsilicon area has driven Copper to replace Aluminum interconnection assilicon technology is scaled beyond 0.25 μm. The front-end change, inturn, pushes wirebond pad pitch from above 100 μm to 80 μm-66μm range. This creates challenges for back-end to probe and wire bondat fine pitch geometry onto a readily oxidized Copper surface. Afterseveral re-metallization structures and types of metallurgy wereevaluated, capping Copper bond pads with Aluminum was selected as theprimary approach for probing and wirebonding Copper devices. Aluminumre-metallization structure offers many advantages that help leverageexisting tooling and knowledge in fab, probing and wire bondingprocesses. This paper will describe probe and wirebond experiments usedto select the proper adhesion and diffusion barrier between Copper andAluminum, and Aluminum thickness that can withstand the mechanicalstress during probing and wire bonding. Probe mark depth and the impactof probe marks to the underlying barrier and Copper pad were examined.Ball shear, wire rip and corresponding failure modes, intermetalliccoverage and cratering analysis were evaluated at various readpoints ofthermal aging study to evaluate the integrity of the re-metallizationstructure as well as the quality of ball bonds onto the new structure.Contact resistance measurement and reliability assessment were alsoperformed. One re-metallization structure was recommended for CopperHigh Performance wire bonded devices
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