Patent ID: 7416989

Claim:
A method of removing a layer of oxide from a substrate surface, the method comprising: (a) exposing a surface of the layer of oxide to dry hydrogen fluoride and allowing the dry hydrogen fluoride to deposit on the layer of oxide until the surface of the layer is partially or fully saturated with the hydrogen fluoride, wherein the dry hydrogen fluoride does not etch the material onto which it is deposited; (b) exposing the substrate to ammonia, whereby hydrogen fluoride and ammonia combine to produce a fluoride etchant in an amount limited by the amount of adsorbed dry hydrogen fluoride in (a); (c) repeating (a) and (b) until a layer of the fluoride etchant is formed in an amount sufficient to etch the underlying oxide by a specified thickness; and (d) applying energy to the substrate to drive off one or more etching by-products of an etching reaction between the fluoride etchant and the oxide.