Mechanically Stable Ultra-Low-K Dielectric and Air-Gap Technology

This paper described two approaches using structured voids in the dielectric among the interconnect metals to achieve low interlayer and intralayer capacitance while maintaining sufficient mechanical strength to withstand the CMP process. The first approach is to use vertically aligned voids and experimental results show that it can be used to achieve very high porosity with much stronger mechanical strength than conventional structures. To further reduce the intralayer dielectric constant, air-gap technology with large void-to-solid ratio has been proposed. The fabrication method and measurement results are presented.