Polymers for high-performance interconnects: Invited lecture

Abstract

It is well known that capacitance in the metallization is becoming too great to allow the continued use of SiO 2 as the intermetal dielectric below about the 0.25 μm technology node. One class of many possible replacements for SiO 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 evolutionary path for their successful integration into a subtractive etch, aluminium-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, particularly via formation. Vapor-deposited polymers like parylene-n which are conformably deposited integrate more easily 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; 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.