Six-port-based compact and low-cost near-field 35 GHz microscopy platform for non-destructive evaluation

A complete millimeter-wave solution with features such as low cost, low-power consumption, compactness, robustness and easy-to-use is proposed to address the need of non-destructive methods with sub-wavelength resolution for operation outside a laboratory environment. The measurement system is based on the association of a low-cost 35 GHz six-port reflectometer and an inexpensive and easy-to-build microstrip evanescent probe with an apex size of 10 μm. The instrumentation can find applications for example in the microelectronic industry where the fast diagnosis of metal layer deposition is of great interest. For demonstration purposes, the technique is applied to the near-field mapping of thin metal layers with a spatial resolution of a few microns. In particular, one-dimensional scanning of rectangular inclusions and imaging of a microsized metallic pattern processed into silicon are experimentally demonstrated to validate the technique. The usefulness and versatility of the method make it also suited for a wide range of applications.