Organothiol-Based Hybrid-Layer Strategy for High-Performance Copper Adhesion and Stress-Migration via Simultaneous Oxide Reduction

The presence of defective native copper-oxide (CuxO) remains a challenge for device technologies owing to its detrimental effects on the adhesion, moisture sensitivity and stress-migration. Here we demonstrate a rapid, single-step, and organic-solvent-free sol-gel deposition process that is capable of simultaneously reducing the weak native Cu-oxide while forming a densely connected Cu/hybrid interface. A marked 9-fold improvement in adhesion is reported, along with a substantial decrease in the Cu stress-migration rate during in-situ isothermal stress-relaxation experiments. The enhanced Cu/hybrid interface adhesion and the improved Cu stress-migration performance were attributed to the partial reduction of the similar to 2 nm native Cu2O layer as demonstrated via atomic-resolution transmission electron microscopy. The hybrid-layer strategy we developed is expected to be effective in not only being a strong candidate for adhesion improvement to Cu, but in promoting Cu stress- and the related electro-migration performance.