The influence of capping layer type on cobalt salicide formation in films and narrow lines

The effect of capping layer (Ti vs TiN) on CoSi formation and CoSi 2 sheet resistance has been investigated. Resistance measurements and XTEM analysis have been used to show that the Ti cap lowers the activation energy for CoSi formation by gettering the O 2 from the RTA (rapid thermal anneal) ambient and eliminating the formation of SiO 2 between the growing CoSi and the Co. The sheet resistance of cobalt silicide formed from Co/Ti and Co/TiN bilayers on poly- Si lines was measured as a function of linewidth and RTA temperature. With a Ti cap, the sheet resistance is low and independent of temperature, and the RTA process window is large.