HIGH-RELIABILITY INTERCONNECTIONS FOR ULSI USING AL-SI-PD-NB/MO LAYERED FILMS

A new Al-Si-Pd-Nb alloy and a bilayered interconnection using this alloy with molybdenum have been investigated for ULSI interconnections. The electromigration life-time of Al-Si-0.3 wt % Pd-0.4 wt % Nb was 5 times better as compared to Al-Si-0.5 wt % Cu. In addition, by layering this alloy with low-resistivity molybdenum, the electromigration resistance improved considerably as compared to Al-Si-Cu layered with a high-resistivity metal, i.e., TiW. PdO was thought to be formed on the Al-Si-0.3 wt % Pd-0.4 wt % Nb alloy's surface. The corrosion resistance of this alloy is much better than that of Al-Si-Cu because of this PdO. The ease in patterning the alloy at submicrometer linewidths (to 0.5-mu-m) is quite satisfactory. The Al-Si-Pd-Nb/Mo layered system is therefore thought to be promising for future interconnection applications requiring durability against high current densities.