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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

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.

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1. A method for etching oxide on a semiconductor substrate, comprising the steps of: producing a positive electrical charge on the oxide; and subsequent to the positive electrical charge production, exposing the previously positively charged oxide on the substrate to hydrofluoric acid vapor and

1. A method for etching oxide on a semiconductor substrate, comprising the steps of: producing a positive electrical charge on the oxide; and subsequent to the positive electrical charge production, exposing the previously positively charged oxide on the substrate 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 saturated monolayer of etch reactants and products produced by the vapor as the oxide is etched by the vapor. 2. A method for etching oxide on a semiconductor substrate, comprising the steps of: producing a positive electrical charge on the oxide; and subsequent to the positive electrical charge production, exposing the previously positively charged oxide on the substrate to hydrofluoric acid vapor and methanol vapor in a process chamber held at temperature and pressure conditions that are controlled to form on the substrate no more than a saturated monolayer of etch reactants and products produced by the vapor as the oxide is etched by the vapor. 3. A method for etching oxide on a semiconductor substrate, comprising the steps of: producing a positive electrical charge on the oxide; and subsequent to the positive electrical charge production, exposing the previously positively charged oxide on the substrate to hydrofluoric acid vapor and isopropyl alcohol vapor in a process chamber held at temperature and pressure conditions that are controlled to form on the substrate no more than a saturated monolayer of etch reactants and products produced by the vapor as the oxide is etched by the vapor. 4. The method of any of claims 1,2, or3 wherein the process chamber temperature and pressure conditions are controlled to form on the substrate no more than a sub-monolayer of etch reactants and products produced by the vapor as the oxide is etched by the vapor.5. The method of any of clam 1,2, or3 wherein the positive electrical charge is produced on the oxide by exposure of the oxide to an electron beam.6. The method of any of claims 1,2, or3 wherein the positive electrical charge is produced on the oxide by exposure of the oxide to ultraviolet light through an electrically-biased metallic screen.7. The method of any of claims 1,2, or3 wherein the positive electrical charge is produced on the oxide by exposure of the oxide to a plasma environment wherein the substrate is capacitively biased by a negative-polarity DC voltage.8. A method for etching oxide on a semiconductor substrate, comprising the steps of: producing a negative electrical charge on the oxide; and subsequent to the negative electrical charge production, exposing the previously negatively electrically charged oxide on the substrate 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 multilayer of etch reactants and products produced by the vapor as the oxide is etched by the vapor. 9. The method of claim 8 wherein the negative electrical charge is produced on the oxide by exposure of the oxide to a plasma environment wherein the wherein the substrate is capacitively biased by a RF voltage.10. The method of claim 8 wherein the negative electrical charge is produced on the oxide by exposure of the oxide to a plasma environment wherein the substrate is capacitively biased by a positive-polarity DC voltage.