Suppression of high-resistance phases of Ni silicide by Se passivation of Si(100)

Abstract

High-resistance phases of Ni-rich Ni silicide are formed on Si(100) below 400/spl deg/C, while high-resistance phases of Si-rich Ni silicide are formed above 600/spl deg/C. The desired low-resistance NiSi is formed between 400/spl deg/C and 600/spl deg/C. In this paper, the authors report the suppression of high-resistance phases of Ni silicide by passivating the Si(100) surface with a monolayer of Se. A 500-/spl Aring/ Ni on n-type low 10/sup 15/ cm/sup -3/ doped Si(100) wafers, passivated with Se, shows a sheet resistance of /spl sim/2.55 /spl Omega//square upon annealing between 200/spl deg/C and 500/spl deg/C, while the sheet resistance of the 500-/spl Aring/ Ni on identical wafers without Se-passivation jumps to /spl sim/7.92 /spl Omega//square between 300/spl deg/C and 350/spl deg/C. Between 600/spl deg/C and 700/spl deg/C, the sheet resistance of the Se-passivated samples is /spl sim/ 10% lower than that of the control samples. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy all confirm that the suppression of high-resistance Ni silicides below 500/spl deg/C is attributed to the suppression of silicidation and above 600/spl deg/C to the delay in Si-rich Ni silicide formation at the Ni/Se-passivated Si(100) interface.