BICMOS devices under mechanical strain

The drain current (I_ds) enhancements of the strained-Si and control Si MOSFET devices under the external mechanical strain are investigated. The uniaxial tensile strain parallel (perpendicular) to the channel can enhance the drive current, while the compressive strain can reduce the drive current of the NMOS devices. The I_ds of control Si NMOSFET with high-κ HfO₂ gate dielectric can be further improved by the external strain. The biaxial tensile strain improves the drive current of NMOS devices. The uniaxial and biaxial tensile strain can reduce the current gain (β = I _c/I_B) of BJT and HBT devices, while the compressive strain can increase the current gain. The current gain change of the Si BJT and SiGe HBT devices under the external stress can be explained by the combinational effects of the mobility and the intrinsic carrier concentration due to the strain.