Reverse short-channel effects on threshold voltage in submicrometer salicide devices

摘要

A reverse short-channel effect on threshold voltage caused by the self-aligned silicide process in submicrometer MOSFETs is reported. A physical model of lateral channel dopant redistribution due to the salicide process is proposed. The injection of vacancies and lattice strain during TiSi/sub 2/ formation causes defect-enhanced boron diffusion which results in a nonuniform lateral channel dopant redistribution and hence a threshold increase in short-channel devices. In addition to the small gate edge birds beak and the nonuniform oxidation-enhanced diffusion (OED) redistribution of channel dopant due to the polysilicon gate reoxidation, the self-aligned Ti silicide process can be major cause of the observed reverse short-channel effect in submicrometer MOSFET devices.