Quantitative Analysis of 2-D Electrostatic Potential Distributions in 90-nm Si pMOSFETs Using Off-Axis Electron Holography

Off-axis electron holography has been used for quantitative analysis of 2-D electrostatic potential distributions in 90-nm Si p-channel MOSFETs (pMOSFETs). The sample preparation for electron holography is based on focused-ion-beam (FIB) and low-energy (3 keV) Ar-ion backside milling. The measured electrostatic potentials from two pMOSFETs with different offset spacer oxide widths are compared in terms of the separation of extension junctions and source/drain (S/D) junctions. The metallurgical gate length (L_met) and the S/D junction encroachment (deltaL) under the gate are measured and compared for the two devices. The electrostatic potential abruptness and electric field intensity are investigated around the drain side, and the lateral and vertical electric field intensities are also compared.