Effect of argon or nitrogen pre-amorphized implant on SALICIDE formation for deep sub-micron CMOS technology

A Ti-SALICIDE process incorporating an argon or nitrogen-amorphization implantation prior to silicidation to enhance the C54-TiSi₂ formation for deep submicron CMOS devices is presented. It was found that by incorporating a high-temperature titanium deposition at 400 °C together with argon-amorphization at a dosage of 3X10¹⁴ cm^-2 to 6X10¹⁴ cm^-2, excellent sheet p was obtained for gate lengths down to 0.25 μm. The improvement seen using a lower temperature (100°C) deposition was relatively less. We postulate that the higher deposition temperature ensures that the C54 phase is nucleated before the C49 phase forms large grains. No noticeable difference was observed for dosages ranging between 3X10¹⁴ cm^-2 and 6X10¹⁴ cm"^-2for the argon implant. In the case for nitrogen- amorphization, the improvement seen on the narrow polyS/ gate was also promising. The impact of dopants on silicidation was evaluated and discussed. Drawbacks of this technique appear to manifest in the compromised integrity of the source/drain junctions, and higher gate-to-source drain leakages, as evident in the case of argon and nitrogen amorphization implants. The anomalous leakage behaviour observed for both argon and nitrogen was however not evident in the case of the arsenic implant. Comparable performance to the SALICIDE process with no pre-amorphization with respect to the leakage parameters was achieved for the arsenic-amorphized wafers.