Thin cobalt silicide formation, including two phase transitions, was studied using a single-wafer rapid thermal furnace (SRTF) system. TiN-capped cobalt films on four types of wafer surfaces (monocrystalline Si, amorphous Si, n{sup}+ amorphous Si, and p{sup}+ amorphous Si) were investigated. Cobalt silicide process sensitivity was investigated in nitrogen ambient as a function of process temperature (350～700°C) and wafer surface condition. Process time (wafer residence time in a preheated near-isothermal process chamber) was fixed at 90s for simplicity. The cobalt silicidation showed two characteristic transition regions, one at about 450°C, and the other at between ～500°C and ～630°C, representing the two phase transitions during the silicidation sequence. The first transition temperature was at about 450°C regardless of wafer surface type. However, the second transition temperature was strongly influenced by the type of wafer surface. We focus our analysis on sheet resistance (sheet ρ) and sheet ρ uniformity of TiN-capped 9 nm thick cobalt films. Except for the phase transition regions around 450°C and 500～630°C, the sheet ρ uniformity has improved as a result of annealing.
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