Characteristics variation in metal oxide semiconductor field effect transistors (MOSFETs) is considered as one of the road blocks in device downscaling. Variation in threshold voltage (V_th) can greatly undermine the device yield and performance. Systematic layout parameters dependence of V_th has been shown using computer simulation and electrical measurement. MOSFET feature size downscaling is usually accompanied by the shrinking of ion implantation boundaries length scales in both length and width directions. Interstitial silicon (I_s) atoms are generated by ion recoiling in high dose boron (B) ion implantation process. During thermal annealing, I_s atoms are injected from ion implantation end of ranges. The injected I_s can either form mobile boron-interstitial (B-I_s) clusters and result in transient enhanced diffusion (TED) or be annihilated through recombination with its traps such as vacancies or surface traps. The dimensionality of ion implantation boundaries define the distributions of end of range defects and therefore affect the local dopant transient diffusion and activation. By using scanning capacitance microscopy (SCM), we were able to measure the nanometer scale dopant diffusion variation issues relative to ion implantation boundary dimensionality and confinement length scales. We also developed a non-linear logistic model for explanation of the SCM measurement. Current ongoing study includes evolution of defect loops in later stage of recrystallization and its relation to confinement length scales, and confinement length scale dependent dopant diffusion in amorphized regions. Besides SCM, we have established collaborative relation with our Spanish collaborator in understanding the above issues with kinetic Monte-Carlo simulation.

Involved lab members: