A Self-Aligned Air Gap Interconnect Process

A self-aligned air gap interconnect structure with sidewall reinforcement is developed. The new structure lowers the capacitance of 0.09um/0.09um (w/s) metal wires by as much as 25%, and exhibits low leakage current. As compared to un-protected air gaps, the structure also greatly improves the electromigration resistance and the misalignment margin for unlanded vias. Furthermore, the sidewall protection layer strengthens the overall mechanical strength and increases the packaging reliability.