Improved Plasma Resistance for Porous Low-k Dielectrics by Pore Stuffing Approach

Abstract

The pore stuffing method is studied with the objective of improving the plasma induced damage for porous organo-silicate glass low-k dielectrics. Experiments on blanket films show that, pore stuffing reduces the low-k degradation compared to non-protected porous films during plasma etch. The post etch surface roughness is also improved. The protection mechanism is attributed to reduced radical penetration, mainly fluorine and oxygen. The resistance against vacuum UV degradation is also improved by pore stuffing, since polymers used as filling agents have a higher VUV absorption coefficient than Si–O based dielectric network. The protection effect against fluorocarbon-based gas discharges is extensively studied with both blanket and patterned samples. For patterning of porous, non-stuffed low-k films, the addition of polymerizing gas reduces surface plasma damage but this polymerizing protection effect doesn't work well on trench sidewalls. Pore stuffing enables an efficient sidewall protection even with oxidizing gas discharges.