Understanding the interfacial layer formation on strained Si1−xGex channels and their correlation to inversion layer hole mobility

We investigate the mechanism of interfacial layer formation on Si _1-x Ge _x (0 <; x <; 0.5) channel and its correlation to hole mobility. It is found that the mobility degradation in low-Ge-content Si _1-x Ge _x (x <; 0.2) pFETs is attributed to a Ge-rich top surface in the channel directly induced by interfacial layer formation. In addition, the depth profile of a Si-rich top surface in high-Ge-content Si _1-x Ge _x channel is presented to understand the surface atomic configuration of Si _1-x Ge _x channel as well as mobility enhancement mechanism.