Non-Invasive Measurements of Thickness of Superconductor Films by Using Two-Resonant-Mode Rutile Resonator

The film thickness should be known for extracting the intrinsic surface resistance from the effective surface resistance as measured by using the dielectric resonator method. Thicknesses of 70 nm to 360 nm are measured for YBa₂Cu₃O_7-δ films in a non-invasive way by using the two-resonant-mode dielectric resonator (TDR) method. A rutile resonator with the respective resonant frequencies of 15.25-15.61 GHz and 15.10-15.37 GHz for the TE₀₂₁ and the TE₀₁₂ modes is used for this purpose. Differences between the values as measured by using the TDR technique and those measured by using a step profilometer appear to be less than 3%, which is smaller than the previous value of 5% as measured by using a 8.6 GHz single-resonance mode rutile resonator Lee et al. J. Korean Phys. Soc. 54(2009)1619. Merits of using the TDR method are discussed.