High-density plasma patterning of low dielectric constant polymers: A comparison between polytetrafluoroethylene, parylene-N, and poly(arylene ether)

Abstract

The pattern transfer of SiO2 hard masks into polytetrafluoroethylene, parylene-N, and poly(arylene ether) (PAE-2) has been characterized in an inductively coupled plasma source. Selected results obtained with blanket parylene-AF4 films are included in this work. These dielectrics offer a relatively low dielectric constant (k∼2–3) and are candidate materials for use as intra- and interlayer dielectrics for the next generations of high-speed electronic devices. Successful patterning conditions were identified for Ar/O2 and N2/O2 gas mixtures. It was found that the formation of straight sidewalls in Ar/O2 discharges relies on the redeposition of oxygen-deficient etch products on the feature sidewall. Furthermore, the etch rates of parylene-N, parylene-F, and PAE-2 for blanket and patterned films could be captured by a semiempirical surface coverage model, which balances the adsorption rate of oxygen and the ion-induced desorption rate of oxygenated etch products.