High - Mobility, Low Parasitic Resistance Si/Ge/Si Heterostructure Channel Schottky Source/Drain PMOSFETs

Abstract

We have built high performance PMOSFETs on Si substrates using a Si/Ge/Si heterostructure channel and NiSi source/drain regions. These devices exhibit ~2X improvement in mobility and orders of magnitude increase in the drive current without adversely affecting the OFF state leakage. In conclusion, using a thin Ge layer within the inversion region of a Schottky Si - PMOSFET provides for higher hole mobility (~2X) and much higher drive currents due to almost zero barrier height to holes in the channel. Also the OFF state leakage is maintained at a low value because it is limited by the large barrier height in the wider bandgap Si and Ge quantization. The transistor hence, combines the advantages of high mobility, and low parasitic resistance and is an attractive candidate for scaling PMOSFETs into the sub-20nm regime.