High aspect ratio features are formed in a substrate using etching and deposition processes. A partially etched feature is formed by exposure to plasma in a plasma etch chamber. A metal-based liner is subsequently deposited in the partially etched feature using the same plasma etch chamber. The metal-based liner is robust and prevents lateral etch in subsequent etching operations. The metal-based liner may be deposited at temperatures or pressures comparable to temperatures or pressures for etch processes. The metal-based liner may be localized in certain portions of the partially etched feature. Etching proceeds within the feature after deposition without lateral etching in regions where the metal-based liner is deposited.