US Patent 7071532 Adjustable self-aligned air gap dielectric for low capacitance wiring

An adjustable self aligned low capacitance integrated circuit air gap structure comprises a first interconnect adjacent a second interconnect on an interconnect level, spacers formed along adjacent sides of the first and second interconnects, and an air gap formed between the first and second interconnects. The air gap extends above an upper surface of at least one of the first and second interconnects and below a lower surface of at least one of the first and second interconnects, and the distance between the spacers defines the width of the air gap. The air gap is self-aligned to the adjacent sides of the first and second interconnects.