The authors investigated the impact of plasma damage on cobalt silicidation. The sheet resistance of CoSi2 was influenced by the damaged layer formed in the Si surface by exposure to CH2F2 or CF4 plasma. The sheet resistance depends largely on the thickness of the damaged layer (T-dl). T-dl could be related to the projected range of the ion which is accelerated by sheath potential. The high peak energy (E-high) of the ion energy distribution was estimated using Monte Carlo simulation. T-dl depended on the projected range calculated using E-high. In addition, the damaged layer was deeper after exposure to plasma with a light ion as the hydrogen ion. On the basis of the results of our experiments, we concluded that it is important to control the mass and the high peak energy of the ions simultaneously in order to achieve lower sheet resistance in high-speed complementary metal oxide semiconductor devices. (c) 2007 American Vacuum Society.