Polymers for high performance interconnects

It is well-known that capacitance in the metallization is becoming too great to allow the continued use of SiO/sub 2/ as the intermetal dielectric below about the 0.25 /spl mu/m technology node. One of many possible replacements for SiO/sub 2/ are organic polymers. Organic polymers are not drop-in replacements, however, and their successful integration into functional circuits requires new fabrication procedures and integration schemes. The embedded dielectric scheme offers a sound evolutionally path for their successful integration into a subtractive etch, aluminum-based integrated circuit. The embedded dielectric scheme effectively lowers total capacitance and the line-line/total capacitance ratio while minimally changing the rest of the metallization fabrication processes including via formation. Vapor deposited polymers which are conformably deposited like Parylene-n are more easily integrated into the embedded dielectric scheme than nonconformal spin-on dielectric films. Parylene-n copolymers with dielectric permittivities as low as 2.3 also are excellent candidate materials for use in the embedded dielectric scheme and they also have equivalent thermal stability as the homopolymer. New copolymers with comonomers of different functionality should improve both the adhesion and thermal stability of the intermetal dielectric.