Patent ID: 8043972
Filing Date: 2011-10-25
Classification: H01L

Abstract:
1. 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 ammonia and allowing ammonia to deposit on the layer of oxide until the surface of the layer is partially or fully saturated with ammonia, wherein ammonia does not etch the material onto which it is deposited; (b) exposing the substrate to dry hydrogen fluoride, whereby dry hydrogen fluoride and ammonia combine to produce a fluoride etchant in an amount limited by the amount of adsorbed ammonia in (a), wherein the dry hydrogen fluoride is not capable of etching the layer of oxide and the formed fluoride etchant is capable of etching the layer of oxide; (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.