Preparation and stability of low temperature cobalt and nickel silicides on thin polysilicon films

Silicides of cobalt and nickel are formed on thin (18-100 nm) polycrystalli ne silicon films by in situ vacuum annealing. The dependence of silicide sh eet resistance on silicon film thickness and crystallinity, surface prepara tion, integrity of vacuum during metal deposition, and anneal temperature i s shown. Cobalt and nickel silicides with sheet resistances as low as 30 an d 20 Ohm/square were formed on 18-nm-thick polysilicon films. A surface pre paration method to produce a passivated silicon surface compatible with lar ge area glass substrates is demonstrated. The resistance of nickel and coba lt silicide to chemical reagents used in semiconductor processing is studie d, as is the thermal stability of these films. (C) 2000 American Vacuum Soc iety. [S0734-2101(00)00501-2].