Interfacial phase formation in Cu-Mg alloy films on SiO_(2)

摘要

We report the chemical changes and phase formation at the film-SiO_(2) interface during vacuum annealing of supersaturated Cu-10 at. Mg alloy films sputter-deposited on SiO_(2). High-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and electron energy loss spectroscopy reveal that both Cu and Mg penetrate ～20-40 nm into silica at ～400℃. At higher temperatures Mg reduces SiO_(2) leading to the crystallization of a 35-nm-thick continuous interfacial layer comprised of equiaxed grains of cubic MgO and small amounts (approx.<1 vol ) of monoclinic CuMgSi_(2)O_(6). Manipulating oxide and silicate formation pathways could open up possibilities for the use of Cu alloys to obtain ultra-thin diffusion barriers at Cu-dielectric interfaces for future metallization structures in integrated circuits.