Evanescent microwave probes and their applications in non-destructive quantitative evaluation of materials

This thesis discusses the models, measurement systems, and calibration procedures of Evanescent Microwave Probes (EMP). The applications in evaluation of semiconductor and dielectric materials are also discussed. The extraction of load impedance near the probe tip and TLA (True Logarithmic Amplifier) based EMP systems are the original ideas of this research. Full differential probes that have largest dynamic range and good sensitivity are proposed in this thesis. Sheet resistance as small as 0.2 Ω·cm has been detected using TLA based EMP system with 200 μm diameter tungsten tip at 50 μm stand off. We estimate the sheet resistance sensitivity of the probe (Δρ _σ/ρ_σ) to be 3 × 10−2 at 210 μm stand-off, 1.5 × 10−2 at 50 μm stand-off and 5 × 10−3 at 5 μm stand-off for the 80Ω/square sheet resistance at 1 GHz. Less than 7% error of non-contact permittivity measurement has been achieved using numerical method to estimate the stand-off distance. Microwave Atomic Force Microscopes (μAFM) and microwave characterization of AFM tips are also exploited in this thesis. The details of 200 nm thick Au edge had spatial resolution about 20nm in μAFM images.