PROCESS FOR LOW TEMPERATURE, DRY ETCHING, AND DRY PLANARIZATION OF COPPER

摘要

The subject invention pertains to a method and apparatus for etching copper (Cu). The invention involves passing a halide gas over an area of Cu such that CuX, or CuX and CuX¿2?, are formed, where X is the halide. Examples of halides include CI, Br, F, and I. Once the CuX, or CuX and CuX¿2?, are formed, a reducing gas is passed over the area of Cu for a sufficient time to etch away at least a portion of the CuX, or CuX¿2?, respectively. With respect to a specific embodiment in which CuX and CuX¿2? are produced, the reducing gas can be passed until essentially all of the CuX¿2? is etched and at least a portion of the CuX is etched. Examples of reducing gases include 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 CuX¿2?−Cu¿3?X¿2? metastable line when etching CuX¿2? and to be a CuY−CuX metastable line, when etching CuX¿2 and to be on CuY−CuX metastable line, where Y is the reducing gas element, when etching CuX. Figures 5, 6, and 8, show such metastable lines for Cu, with X being CI, from temperatures ranging from 50ºC to 200ºC. The invention can be used to etch partial into a layer of CU, through a layer of CU, or to smooth a CU surface.