Air gaps lower k of interconnect dielectrics

Established CVD oxide processes can be fine-tuned to produce air gaps betwe en metal lines to lower the k of interconnect dielectric stacks. Design con straints and integration challenges exist, but air gaps may be easier to in tegrate than completely new low-k materials. Manufacturable processes can r educe interconnect capacitance by as much as 40-50% for tightly spaced meta l lines.