Overview of Scanning Microwave Microscopy

Scanning Microwave Microscopy (SMM) is a nanoscale imaging technique that combines the lateral resolution of Atomic Force Microscopy (AFM) with the high measurement precision of microwave analysis at GHz frequencies, provided by Vector Network Analyzers (VNA). SMM enables measuring complex materials properties for nano-electronics, materials science, and life science applications. SMM operates at broadband frequencies between 1 GHz and 20 GHz. We developed novel calibration workflows for complex impedance imaging1-2 and dielectric quantification3. Various nanodevices are studied including dopant profiling layers and high voltage transistors4,5. Based on the high frequency the laborious fabrication of back electrode contacts is not required, making it an easily applicable tool for electrical characterization of nanodevices. The capability of the electromagnetic waves to penetrate the surface of the sample under study allows the technique to be used to selectively sense sub-surface features6. The sub-surface and quantitative resistivity measurement capabilities are demonstrated for silicon back-wafer imaging and semiconductor failure analysis. As will be shown as an ultimate limit even atomically thin regions of dopant atoms in silicon can be electrically characterized and localized in 3 dimensions with nm resolution7. Such dopant structures are building blocks of quantum devices for physics research and it is anticipated that they will also serve as key components of devices for next generation classical and quantum information processing. References: [1] G. Gramse et al, “Calibrated complex impedance and permittivity measurements with scanning microwave microscopy”, Nanotechnology, 25, 145703 (2014) [2] M. Kasper et al, “An advanced impedance calibration method for nanoscale microwave imaging at broad frequency range,” IEEE Transactions on MTT 65, 7, 2017, 2418-24 [3] M.C. Biagi et al, “Nanoscale Electric Permittivity of Single Bacterial Cells at Gigahertz Frequencies by Scanning Microwave Microscopy,” ACS Nano, 10, 280 (2016) [4] E. Brinciotti et al, “Calibrated nanoscale dopant profiling and capacitance of a high-voltage lateral MOS transistor at 20 GHz using Scanning Microwave Microscopy,” IEEE Transactions on Nanotechnology, vol.16, no.2, pp.245-252 (2017) [5] E. Brinciotti et al, “Frequency Analysis of Dopant Profiling and Capacitance Spectroscopy Using Scanning Microwave Microscopy,” IEEE Transactions on Nanotechnology, vol.16, no.1, pp.75-82 (2017) [6] G. Gramse and E. Brinciotti et al, “Quantitative sub-surface and non-contact imaging by scanning microwave microscopy,” Nanotechnology 26, 135701 (2015) [7] G. Gramse et al., Non-destructive imaging of atomically-thin nanostructures buried in silicon. Science Advances 3, 6 (2017