Imaging nano-defects of metal waveguides using the microwave cavity interference enhancement method

Abstract

Here, we demonstrate a microwave cavity interference enhancement method to image the nano-defect on the surface of metal waveguide. The microwave cavity interference system was mainly consist of a MW coaxial resonant cavity with a nano-probe. The MW signals have been evenly divided into two channels. One was the reference signal inputted the MW waveguide and coupled into the MW cavity via the probe. And the coupling strength depends on the distance between the probe and the MW waveguide. Another one was directly inputted the MW cavity to interfere with the reference signal, and enhanced in the cavity. Then, the surface topography of metal waveguide would be mapped by calculating the enhanced signals. In our experiment, a weak signal of ~pW coupled from the waveguide can be detected by a MW cavity with the quality factor of ~1000. As a proof of application example, the topography of nano-defects on the surface of metal waveguide in MW chip have been mapped with a resolution of ~15 nm. It proves a high resolution, easy manufacture, low-cost, and real-time on-line monitoring approach for online assessment and screening chip. It has broad application prospect in the fields of chip manufacturing, chip inspection, nanostructure detection, and so on.