Room temperature observation of velocity overshoot in silicon inversion layers

As MOS transistor dimensions shrink to deep sub-micron regime, the non-local effects are expected to become more prominent. Perhaps the most important of these non-local effects is velocity overshoot, which can be beneficial to device performance by improving current drive and transconductance. Here, for the first time, we report direct observation of velocity overshoot using a special test structure. The first indication of velocity overshoot is seen at channel length of 0.22 μm, while at L_eff=0.12 μm drift velocity values up to 40% higher than the long channel value are measured. The SOI NMOSFETs used in the study are built on SIMOX wafers with channel lengths from 0.12 μm to 0.6 μm