Articles you may be interested inHigh-temperature stability of postgrowth-annealed Al-doped MgxZn1-xO films without the phase separation effect Films of pure Cu and of Cu alloy containing 2.5 at. % of Zr [abbreviated as Cu͑2.5 at. % Zr͒] were deposited on SiO 2 / Si substrates by magnetron sputtering. Samples were subsequently annealed at temperatures ranging from 500 to 800°C in vacuum ͑2 ϫ 10 −5 Torr͒ for 30 min and analyzed by Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, and glancing incident angle x-ray diffraction. Resistivity of both pure Cu and Cu alloy films, before and after annealing, was measured at room temperature by using a standard four-point probe technique. Upon annealing, the added Zr atoms in Cu͑2.5 at. % Zr͒ diffuse to both the free surface and the alloy/ SiO 2 interface and react with the residual oxygen in the vacuum system and with the SiO 2 to form a ZrO 2 layer. At the interface, a self-grown ZrO 2 layer forms upon annealing at 700°C that hinders Cu from diffusion into the SiO 2 , while Cu diffusion into SiO 2 is apparent for pure Cu on SiO 2 at this temperature. The room-temperature resistivity of the as-deposited Cu͑2.5 at. % Zr͒ film is 21.8 ⍀ cm and decreases to about 6.2 ⍀ cm upon vacuum annealing at 700°C for 30 min. This value is still thrice that of the pure Cu film similarly treated. The relation between the diffusion of the added Zr and the characteristics of Cu͑2.5 at. % Zr͒ / SiO 2 interface, self-formed surface layer, and the resistivity change, is discussed.

Thin film reaction of transition metals with germaniumThin films of pure Cu and Cu alloys ͑with 3.9 at. % Ti or 2.3 at. % Ta͒ are deposited on SiO 2 /Si substrates by magnetron sputtering. Upon annealing at 700°C in vacuum for 30 min, Ti in the Cu͑3.9 at. % Ti͒ films will mostly diffuse to the free surface, but the majority of Ta in the Cu͑2.3 at. % Ta͒ film remains within the Cu layer. The outward diffusion of Ti or Ta strongly influences the oxidation of Cu in air. The degree of Cu oxidation was determined by glancing incident angle x-ray diffraction and the normalized sheet resistance. Oxidation test shows that the Cu͑3.9 at. % Ti͒ films exhibit a superior oxidation resistance when oxidized at 200°C in air, especially for the Cu͑3.9 at. % Ti͒ film which has been preannealed at 700°C in vacuum. But the Cu͑2.3 at. % Ta͒ film with the same preannealing treatment only slightly improves the oxidation resistance, in comparison with the pure Cu film. The correlation between outward diffusion of additives and oxidation of Cu in the Cu͑3.9 at. % Ti͒ and Cu͑2.3 at. % Ta͒ thin films is discussed.