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One-Step Wet Chemical Treatment for Fluxless Cu-Sn Thermocompression Microbump Bonding

Year: 2025
Type: article
Abstract: A new one-step wet chemical treatment has been developed for fluxless Cu-Sn microbump bonding. This treatment simultaneously removes native oxide from the Cu surface and deposits a functional layer on the cleaned surface. The treatment passivates the surface against re-oxidation and activates it for thermocompression bonding (TCB) between Cu and Sn without applying a flux agent. This paper discusses oxide layer removal from the Cu surface and the stability of the formed functional layer for up to 45 weeks. Die-to-die (D2D) microbump bonding was also evaluated through conductivity tests after thermal stress. Additionally, the uniformity of the layer formation on a 300-mm wafer-level application was assessed using dipping and spinning methods.
Language: English
Open Access status: bronze
OpenAlex ID: W4416294017
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