The invention provides HF vapor process conditions that can be precisely
controlled with a high degree of reproducibility for a wide range of
starting wafer conditions. These HF vapor processes for, e.g., etching
oxide on a semiconductor substrate, cleaning a contaminant on a
semiconductor substrate, removing etch residue from a metal structure on a
semiconductor substrate, and cleaning a metal contact region of a
semiconductor substrate. In the HF vapor process, a semiconductor
substrate having oxide, a contaminant, metal etch residue, or a contact
region to be processed is exposed to hydrofluoric acid vapor and water
vapor in a process chamber held at temperature and pressure conditions
that are controlled to form on the substrate no more than a sub-monolayer
of etch reactants and products produced by the vapor as the substrate is
processed by the vapor. The sub-monolayer HF vapor process regime is
defined in accordance with the invention to proceed under conditions
wherein no more than about 95% of a monolayer of coverage of the substrate
surface occurs.
