Methods for surface interface engineering in semiconductor fabrication are provided herein. In some embodiments, a method of processing a substrate disposed atop a substrate support in a processing volume of a processing chamber includes: generating an ion species from an inductively coupled plasma formed within the processing volume of the processing chamber from a first process gas; exposing a first layer of the substrate to the ion species to form an ammonium fluoride (NH4F) film atop the first layer, wherein the first layer comprises silicon oxide; and heating the substrate to a second temperature at which the ammonium fluoride film reacts with the first layer to selectively etch the silicon oxide.