Analysis of stress-induced mobility enhancement on (100)-oriented single- and double-gate n-MOSFETs using silicon-thickness- dependent deformation potential

Abstract

The stress effect in uniaxially strained single- and double-gate silicon-on-insulator n-type metal oxide-semiconductor field effect transistors (MOSFETs) with a (100) wafer orientation is analyzed. A model of silicon-thickness-dependent deformation potential (Dac-TSi) is introduced to accurately calculate the mobility using a Schrodinger-Poisson solver. Simulation results using the Dac-TSi model exhibit excellent agreement with the measured mobility for both the unstrained and strained conditions. Electron mobility enhancements with longitudinal and transverse tensile stress conditions are simulated as a function of silicon thickness. The mobility enhancement in the single-gate case has one peak point, whereas it produces two peak points in the double-gate case. An in-depth analysis reveals that this phenomenon results from the hump in the energy difference between the Delta 2 and Delta 4 valleys, which in turn results from the volume inversion in the double gate.