Built-in Potential Mapping of Silicon Field Effect Transistor Cross Sections by Multimode Scanning Probe Microscopy

Abstract

Built-in potential maps of metal-oxide-semiconductor field effect transistors (MOSFETs) with gate lengths of 30 and 150 nm were measured on cross sectional Si(110) surfaces covered with ultra-thin oxide. The maps were obtained by measuring the contact potential difference (CPD) using multimode scanning probe microscopy (MSPM) with a vibrating probe in the constant force mode. The improved spatial resolution and the sensitivity to the electrostatic potential were achieved for an optimal probe-sample gap (～1 nm) and vibration amplitude of 0.2 nm. The capability and challenges of the measurement method are discussed by comparing measured CPD maps with device simulation results.