High reliability interconnections for ULSI using Al-Si-Pd-Nb/Mo layered films

A new Al-Si-Pd-Nb alloy and a bilayered film using this alloy with Mo have been investigated for ULSI interconnections. Al-Si-0.3 wt.%-Pd-0.4 wt.%-Nb was found to have a five-times-better electromigration resistance than Al-Si-0.5% Cu. In addition, by layering this alloy with Mo, electromigration resistance was found to be ten times better than for Al-Si-Cu/TiW. Stress measurements detected the formation of PdO on the alloy's surface and revealed a significant increase in tensile strength. The corrosion resistance of this alloy is much better than that of Al-Si-Cu possibly because of this PdO. The ease in patterning the alloy at submicron linewidths (to 0.5 mu m) is quite satisfactory. The Al-Si-Pd-Nb/Mo layered system is therefore thought to be quite promising for future interconnection applications requiring durability against high current density.<
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