The subject invention pertains to a method and apparatus for
etching copper (Cu). The subject invention can involve passing a
halide gas over an area of Cu such that CuX, or CuX and CuX2, are formed, where X is the
halide. Examples of halides which can be utilized with the
subject matter include, but are not necessarily limited to, Cl, Br, F, and I. Once the CuX, or CuX and CuX2, are formed the subject invention can then involve passing a reducing gas over the area of Cu for a
sufficient time to etch away at least a portion of the CuX, or CuX2, respectively. With respect to a specific embodiment in which CuX and CuX2 are produced when the
halide gas is passed over the area of Cu, the reducing gas can be passed until essentially all of the CUX2 is etched and at least a portion of the CuX is etched. Examples of reducing gases which can be utilized with the subject invention include, but are not necessarily limited to,
hydrogen gas and
hydrogen gas plasma. The subject invention can accomplish the
etching of Cu by passing the reducing gas over the Cu so as to be on a CuX2—Cu3X2 metastable line when
etching CuX2 and to be a CuY—CuX metastable line, where Y is the reducing
gas element, when etching CuX. FIGS. 5, 6, and 8, show such metastable lines for Cu, with X being Cl, from temperatures
ranging from 50° C. to 200° C. These can be extrapolated to other temperatures, for other halides, and / or other reducing gases. The subject invention can be used to, for example, etch partial into a layer of Cu, through a layer of Cu, or to smooth a Cu surface.