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edfas.org ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 19 NO. 4 12 NANOSCALE CAPACITANCE AND CAPACITANCE-VOLTAGE CURVES FOR ADVANCED CHARACTERIZATION OF ELECTRICAL PROPERTIES OF SILICON AND GaN STRUCTURES USING SCANNING MICROWAVE IMPEDANCE MICROSCOPY (sMIM) Oskar Amster, Stuart Friedman, Yongliang Yang, and Fred Stanke PrimeNano, Inc. amster@primenanoinc.com OVERVIEW A relatively new electrical mode, scanningmicrowave impedance microscopy (sMIM), measures a material’s change in permittivity and conductivity at the scale of tens of nanometers. [1] The use of atomic force micros- copy (AFM) electrical measurement modes is a critical tool for the study of semiconductor devices and process development. More specifically, the application of AFM electrical modes is an important tool for characterizing semiconductor devices during process development and failure analysis. The AFM-based electrical measurement techniques, such as scanning capacitance microscopy (SCM) and scanning spreading-resistance microscopy, [2,3] have shown value for dopant profiling in semiconductor sampleswith sub-50nmspatial resolution. However, there has been no single scanning probe technique capable of quantifying at submicron dimensions the local electrical properties of materials (dielectric constant and conduc- tivity) with the sensitivity and dynamic range required by the semiconductor industry and research communities. Scanningmicrowave impedancemicroscopy provides the capability to directly probe a sample’s permittiv- ity and conductivity at submicron geometries. Scanning microwave impedance microscopy provides the real and imaginary impedance (Re( Z ) and Im( Z ), respectively) of the probe-sample interface impedance. By measuring the reflected microwave signal of a sample of interest imaged with an AFM, one can capture in parallel the variations in permittivity and conductivity and, for doped EDFAAO (2017) 4:12-20 1537-0755/$19.00 ©ASM International ® semiconductors, the variations in depletion-layer geom- etry. [4,5] Scanning capacitance microscopy, an existing technique for characterizingdoped semiconductors,mod- ulates the tip-sample bias and detects the tip-sample rate of change of capacitance with bias voltage using a lock-in amplifier. A previous study compared sMIM to SCM and highlighted the additional capabilities of sMIM, [6,7] includ- ing examples of nanoscale capacitance-voltage curves. The initial implementationof sMIM focusedon the rela- tivemeasurement of local permittivity and conductivity at a sample surface. The capability todirectly image the local variationof a sample’s electrical properties at spatial reso- lutions of tens of nanometers has stimulated newareas of research. For technologically and scientifically important materials, such as graphene, [8] carbon nanotubes, [9] fer- roelectric domains, [10,11] and doped semiconductors, [12-14] researchers are actively using this technique to gain new understanding of materials systems behavior. “SCANNING MICROWAVE IMPEDANCE MICROSCOPY PROVIDES THE CAPABILITY TO DIRECTLY PROBE A SAMPLE’S PERMITTIVITY AND CONDUCTIVITY AT SUBMICRON GEOMETRIES.”