| 摘要 |
A semiconductor device having contaminant-reduced calcium-copper (Ca-Cu) alloy surfaces formed on Cu interconnects fabricated by cost-effectively removing the contaminant layer. Contaminant removal from a Cu-Ca-X surface, where contaminant X=C, S, or O, is achieved by sputtering the Cu-Ca-X surface in an argon (Ar) atmosphere between the steps of (a) immersing the Cu interconnect surface into an electroless plating solution comprising Cu salts, Ca salts, their complexing agents, a reducing agent, a pH adjuster, and at least one surfactant for facilitating Ca-doping of the Cu interconnect material; and (b) annealing of the Ca-Cu alloy surface onto the underlying Cu interconnect material to form a Ca-Cu/Cu interconnect structure, whereby the sputtering step, under Ar, selectively and effectively removes contaminants from the Cu-Ca-X layer containing higher concentrations of C, S, or O, thereby minimizing the post-annealed contaminant level, and thereby producing a uniform Ca-Cu alloy surface (i.e., Cu-rich with 0.2-5% Ca) on the Cu interconnect material for maximizing Ca-Cu/Cu interconnect structure reliability, electromigration resistance, and corrosion prevention. The annealing step primarily removes O and secondarily removes C and S, especially when performed under vacuum, an inert gas, or a reducing ambient such as ammonia (NH3) plasma. Thus, the resultant device then comprises a distinctive contaminant-reduced Ca-Cu/Cu interconnect structure.
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