Enhanced Hole Mobility in High Ge Content Asymmetrically Strained-SiGe p-MOSFETs

The hole mobility characteristics of 〈110〉 /(100)-oriented asymmetrically strained-SiGe p-MOSFETs are studied. Uniaxial mechanical strain is applied to biaxial compressive strained devices and the relative change in effective hole mobility is measured. The channel Ge content varies from 0 to 100%. Up to -2.6% biaxial compressive strain is present in the channel and an additive uniaxial strain component of -0.06% is applied via mechanical bending. The hole mobility in biaxial compressive strained-SiGe is enhanced relative to relaxed Si. It is observed that this mobility enhancement increases further with the application of 〈110〉 longitudinal uniaxial compressive strain. The relative change in mobility with applied stress is larger for biaxial compressive strained-SiGe than for Si and increases with the amount of biaxial compressive strain present in the channel.