Calibrated Nanoscale Dopant Profiling and Capacitance of a High-Voltage Lateral MOS Transistor at 20 GHz Using Scanning Microwave Microscopy

Abstract

We quantitatively image the doping concentration and the capacitance of a high-voltage lateral metal-oxide-semiconductor transistor device with a channel length of 0.5 μm at 20-GHz frequency using scanning microwave microscopy (SMM). The transistor is embedded in a deep n-well forming a flat pn-junction with the p-substrate, with the shape of the pn-junction resolved in the SMM images. Calibrated dC/dV imaging of the device revealed doping concentration values in the range of 1015–1019 atoms/cm 3, including the p-body, n-drift region, n-source-diffusion, as well as all the pn-junctions and the silicon/oxide interfaces at a minimum feature size of 350 nm and SMM electrical resolution of 60 nm. SMM doping concentrations have been compared with technology computer-aided design simulations, resulting in a quantitative agreement between model and experiment. dC/dV images have been acquired at different tip dc bias voltages, allowing to determine the p and n dopant polarity. From the reflection scattering S11 signal calibrated capacitance measurements have been obtained from the various transistor regions in the range of 300 aF to 1 fF. The results suggest that both dC/dV dopant profiling and capacitance measurements can be used for quantitative nanoscale semiconductor device imaging.