Process integration compatibility of low-k and ultra-low-k dielectrics

摘要

Damage of plasma-enhanced chemical vapor deposited SiOCH films on exposure to typical plasma etch, plasma ash and wet clean processes are investigated. Dielectrics of k=3.0, 2.5, and 2.2 show little film damage with standard fluorine chemistry plasma etch, but experience severe film degradation on exposure to a typical oxygen plasma ash, used to remove photoresist. Effects of film damage on exposure to oxidative plasma ash include film densification, Si-OH formation, water adsorption, and dielectric constant increases. Theses effects are found to be more severe for the higher porosity, lower-k films, and are unrecoverable with thermal anneal.