Saturation transconductance of deep-submicron-channel MOSFETs

A new method is described for extracting electron and hole saturation velocities from saturation currents of deep-submicron-channel N- and PMOSFET's at room and low temperatures. The extracted results are (7 ± 0.5) × 10⁶ cm/s at 300 K and (8 ± 0.5) × 10⁶ cm/s at 77 K for electrons; and (7 ± 1) × 10⁶ cm/s at both 300 and 77 K for holes. These numbers are used in an analytical model to calculate the MOSFET saturation transconductance as a function of channel length. Excellent agreement is obtained between the experimentally measured saturation transconductance at 300 and 77 K and the model calculations over a wide range of channel length from 10 to 0.15 μm. This also sets up a procedure for identifying the onset of velocity overshoot, which is reflected in the 77 K NMOSFET data below 0.25 μm.