Activation characterization of the Ti-Zr-V getter films deposited by magnetron sputtering

Abstract

Non-evaporable getter (NEG) thin films provide distributed pumping properties, allowing to achieve ultrahigh vacuum in narrow and conductance limited chambers. It is an ideal solution to deal with the small aperture of vacuum chambers. In this paper, ternary Ti-Zr-V getter film with approximate equal atomic ratio was deposited on oxygen free copper (OFC) substrate by using a developed DC magnetron sputtering system with an alloy target. Microstructural characterization by scanning electron microscopy, atomic force microscopy and energy dispersive spectroscopy (EDX) indicates that the porous getter film exhibit a columnar growth pattern and the grain sizes are very distributed ranging from several up to hundreds of nanometres. The compositions and the corresponding chemical bonding states are analyzed by using in-situ synchrotron radiation X-ray photoelectron spectroscopy after activation for 1 h at different temperatures in ultra-high vacuum. The results indicate that Ti, Zr and V are initially in their high oxidized states, which are gradually reduced in steps to oxides of lower valence states and finally to their metallic states. The reduction of vanadium oxides is more preferable than that of titanium- and zirconium-oxides. Such activation commences at a temperature as low as 150 °C, and can be enhanced by increasing temperature.