Abstract: Methods for selective etching of one layer or material relative to another layer or material adjacent thereto. In an example, a SiGe layer is etched relative to or selective to another silicon containing layer which either contains no germanium or geranium in an amount less than that of the target layer.

Abstract: An etching method includes: forming a protective film by supplying a protective film forming gas including at least one of a compound including a hydroxyl group and water to a substrate including a surface on which a first film and a second film are formed, each of which has a property of being etched by an etching gas, wherein the protective film covers the first film such that the first film is selectively protected from among the first film and the second film when the etching gas is supplied; and selectively etching the second film by supplying the etching gas to the substrate in a state in which the protective film is formed.