Electrical properties of creep-resistant nanocrystalline gold-vanadium thin films at millimeter-wave frequencies

This paper reports on the mechanical and electrical properties of creep-resistant nanocrystalline gold-vanadium (Au-V) thin films that are employed in electrostatically-actuated microcorrugated diaphragms (MCDs) of frequency-reconfigurable all-silicon cavity filters. Solid solution strengthened Au-V MCDs featuring the lowest stress relaxation to date were built and experimentally tested. In a 3-hour stress relaxation experiment under a 20-μm constant displacement, they exhibited a 6.2% decay and a rate of stress relaxation (at the 3rd hour) that is 9.7×/5.4× lower than that of previously reported Au/Au-V MCDs. Grounded coplanar waveguide transmission lines were built and measured on a quartz substrate in order to experimentally evaluate the electrical properties (sheet resistance: Rs, conductivity: σ, and attenuation factor: α) of the Au-V thin films through DC and RF measurements in the 20-40 GHz band. These were specified as follows for the annealed Au-V (2.2 atomic percent of V) thin films: Rs = 339.10 mΩ/□, σ = 5.9 MS/m, α = 0.327-0.410 dB/mm.