Suppression of Defect Formation and Their Impact on Short Channel Effects and Drivability of pMOSFET with SiGe Source/Drain

The impact of defects on the short channel effects (SCE) and the drivability of a pMOSFET with a SiGe source/drain is described, and useful methods to reduce defect formation are suggested. The influence of defects on device performance is found to become more severe as recess depth increases and/or channel length decreases. By optimizing the epitaxial process, including an in-situ precleaning step, the initial defect density is reduced, and by introducing a cap layer on a SiGe layer, the thermal stability of the SiGe layer is improved. The optimized devices enhance mobility 42% by maximizing the strain effect and provide better SCE characteristics by suppressing boron diffusion.