Electron Velocity Overshoot in Sub-100-nm Channel Length Metal-Oxide-Semiconductor Field-Effect Transistors at 77 and 30 K

摘要

We have reported previously on the fabrication, using x-ray lithography, of silicon metal oxide semiconductor field-effect transistors (MOSFETs) having channel lengths ranging from 60 nm to 5 micro. Devices with channel lengths of 75 nm showed electron velocity overshoot at 4.2 K. We have improved the mobility of the short-channel MOSFETs by implanting with B and then growing the gate oxide rapidly such that the concentration in the inversion layer is about 2 x 10 to the 16th/cc rather than the 5 x 10 to the 17th/cc used previously. A peak concentration of 2.2 x 10 to the 17th/cc occurs at a depth of 0.19 micro, where it prevents punchthrough by screening the field lines from the drain. With devices having channel lengths shorter than 100 nm we measured mean electron velocities at 300 and 77 K that exceeded 10 to the 7th and 1.3 x 10 to the 7th cm/s, the bulk saturation velocities at these two temperatures. The highest mean velocity measured at 77 K was 2.3 x 10 to the 7th cm/s. Semiconductors, Reprints. (mjm)