Electromagnetic Modeling in Near-Field Scanning Microwave Microscopy Highlighting Limitations in Spatial and Electrical Resolutions

Near-field scanning microwave microscopy (NSMM) is a scanning probe microscopy (SPM) technique that measures the local interaction of evanescent microwaves with a sample using a sharp tip probe. The traceability in NSMM is still challenging as the distribution of the electrical fields is affected by several parameters. In this effort, finite element method (FEM) based electromagnetic modeling methods are used to study the effects of the wavelength of operation and the humidity on the spatial and electrical resolutions respectively. From the simulated data, it is demonstrated that the lateral resolution is improved with increasing the frequency of operation. Furthermore, the existence and influence of a water meniscus is highlighted by fine comparison between simulated and measured data. To face these issues, an alternative near-field scanning millimeter-wave microscopy working in a controlled environment is proposed.