Reactivity of oxide surfaces and metal-oxide interfaces: Effects of water vapor pressure on ultrathin aluminum oxide films, and studies of platinum growth modes on ultrathin oxide films and their effects on adhesion

The reactivity of oxide surfaces and metal-oxide interfaces play an important role on many technological applications such as corrosion, heterogeneous catalysis, and microelectronics. The focus of this research was (1) understanding the effects of water vapor exposure of ultrathin aluminum oxide films under non-ultrahigh vacuum conditions (>10-9 Torr) and (2) characterization of Pt growth modes on ultrathin Ta silicate and silicon dioxide films and the effects of growth modes on adhesion of a Cu overlayer. These studies were conducted with X-ray photoelectron spectroscopy (XPS).; Ni3Al(110) was oxidized (10-6 Torr O 2, 800K) followed by annealing (1100K). The data indicate that the annealed oxide film is composed of NiO, Al2O3 and an intermediate phase denoted here as "AlOx". Upon exposure of the oxide film at ambient temperature to increasing water vapor pressure (10 -6--5 Torr), a shift in both the O(1s) and Al(2p) oxide peak maxima to lower binding energies is observed. In contrast, exposure of Al2O3/Al(polycrystalline) to water vapor under the same conditions results in a high binding energy shoulder in the O(1s) spectra which indicates hydroxylation. Spectral decomposition provides further insight into the difference in reactivity between the two oxide films. The corresponding trends of the O(1s)/Ni0(2p3/2) and Al(2p)/Ni0(2p3/2) spectral intensity ratios suggest conformal changes of the oxide film on Ni3Al(110); The growth behavior of sputter deposited Pt at ∼300K on Ta silicate and SiO2 ultrathin films formed on S0(100) was investigated. The XPS data show that Pt deposition results 0n uniform growth or "wetting" on Ta silicate and 2-D cluster growth on SiO2. Electroless Cu deposition on ∼11 monolayers (ML) Pt/Ta silicate film results in an adherent Cu film which passed the Scotch tape test. In contrast, electroless Cu deposition on ∼11 ML Pt/SiO2 results in a non-adherent Cu film due to weak Pt/SiO2 interaction.