Fabrication and characterization of e-beam defined MOSFETs with sub-micrometer gate lengths

Well-behaved n-channel MOSFETS with polysilicon gate lengths as small as 0.5µm have been fabricated using E-Beam direct slice writing, anisotropic plasma etching and ion implantation techniques. Implant profiles were optimized using SUPREM to reduce short channel effects such as punch-through, drain modulation and subthreshold leakage. Gate overlap of the diode regions was minimized by implanting arsenic through a conformal oxide layer, thereby enhancing the effective channel length relative to patterned dimensions and reducing Miller effect capacitance. Fabricated MOSFETS with gate lengths as small as 0.5µm exhibited good off-state behavior with drain voltages as high as 5 volts. Measured data were fitted within 5% to both a modified SPICE model and a short channel charge-sharing model.