Physical understanding of Vth and Idsat variations in (110) CMOSFETs

In this paper, the first systematic study of V_th variations (sigmaV_th) and I_dsat variations (sigmaI_dsat) in (110) n/pMOSFETs is presented. sigmaV_th in (110) n/pFETs with high channel dose are larger than (100) n/pFETs. It is found that the variations of B ion channeling, B-induced interface traps, and As-induced interface fixed charges enhance sigmaV_th in (110) n/pFETs. Steep B profile and moderate P doping into the surface are desirable to minimize sigmaV_th in (110) FETs. We also found that sigmaI_dsat is determined by both sigmaV_th and the degree of velocity saturation. sigmaI_dsat of scaled (110) CMOS can be lowered compared to (100) CMOS by the optimum channel impurity design.