Dependence of contact resistance on substrate doping and impact of mixed ion implantation

The dependence of contact resistance (R-C), especially metal contact on p()-Si, has been investigated with several processes such as the etching of c ontact hole and the doping of junction region. In order to obtain highly re liable contact characteristics in deep submicron devices, it is found that the oxide etching process with high selectivity to silicon and the high sur face doping concentration in contact open area are required. The R-C can be reduced about 50% by adopting high selectivity etching process. High surfa ce concentration made by BF2 and B mixed implantation shows 20% reduction o f R-C, while plug implantation can improve R-C by 50%. Optimized doping pro file combined with high etch selectivity is indispensable for low R-C, beca use substrate loss is unavoidable. These results are also confirmed by proc ess simulation using the measured parameters such as the contact depth by T EM and the doping profile by SIMS.