Fabrication and transport measurements of atomic force microscope modified silicon metal-oxide-semiconductor field-effect transistors

The channel areas of n-channel silicon metal-oxide-semiconductor (MOS) field-effect transistor devices have been patterned with a modified atomic force microscope operated in air. Grating nanostructures were fabricated both parallel and perpendicular to the direction of electron travel using a direct write process. The gratings were transferred into both the gate oxide as a thickness modulation and directly into the silicon substrate. Subsequent MOS processing steps were completed and the devices were electrically tested. Measurements made on devices with gate oxide thickness modulations operated near threshold indicated different mobilities corresponding to the different grating orientations. This is likely due to local threshold shifting resulting from the grating induced surface potential modulation in the silicon channel.