Comparison between <100> and <110> oriented channels in highly strained FDSOI nMOSFETs

Abstract

We fabricated highly stressed FDSOI nMOSFETs down to 18nm gate length. The impact of different stressors (CESL, STI) is studied for different device geometries and substrates orientation (<100> or <110>). We evidence that STI degrades wide devices of intermediate gate length (0.2μm<L G <1μm) along <100> compared to <110> (-20% mobility) whereas short nMOSFETs are improved along <100> with a (1.6 GPa) tensile CESL (+15% mobility, +6% I ON ). The CESLinduced mobility enhancement can be reproduced rather well for the two channel orientations by the piezo-resistive model and an analytical model of the stress profile.