On-state performance enhancement and channel-direction-dependent performance of a biaxial compressive strained Si_0.5Ge_0.5 quantum-well pMOSFET along 〈 110 〉 and 〈 100 〉 channel directions

pMOSFET performance of high Ge content (∼50%) biaxial compressive strained SiGe heterostructure channel pMOSFETs is characterized, and performance between 〈 110 〉 and 〈 100 〉 channel orientations on a (001) substrate is compared for physical channel lengths down to ∼80 nm. Temperature-dependent mobility and velocity are characterized for both channel directions. First, it is shown that high Ge content SiGe-based channels can deliver drive current enhancement over unstrained Si below sub-100-nm channel lengths. Second, it is found that, with a higher Ge content SiGe channel under biaxial compressive strain, there is a difference of drive current between 〈 110 〉 and〈 100 〉 channel directions, and the difference increases when temperature is lowered and/or when channel length is scaled down. An external series resistance difference is detected between two channel directions, although it appears to be insufficient to explain all the direction-dependent drive current difference. Channel transport behavior in different channel orientations can be clearly observed with low external source/drain (S/D) series resistance achieved with a millisecond S/D dopant activation anneal process while controlling the thermal budget. Two possibilities have been investigated to understand channel-direction-dependent performance: possible differences in effects of device processing impact between two channel directions and anisotropic transport effects from an anisotropic hole band structure, particularly under biaxial compressive strain in a SiGe channel pseudomorphically grown on a Si substrate.