Contact resistance behavior of the Pd2 Si-AlCuSi system

Aluminum to silicon contact resistance, R_c , is influenced by the choice of intermediate contact and interconnection metallurgies, as well as anneal cycles associated with metallization and post-metallization passivation processes in single and multi-level metal VLSI technologies. This is particularly evident for the metallurgical system comprised of palladium silicide, Pd₂ Si, and AlCuSi. This system has been investigated to ascertain the relationships between R , anneal time, and anneal temperature for various Pd Si thicknesses of AlCuSi contacts to N⁺ single-crystal silicon and polysilicon. The evaluations revealed that R_c and R_c distribution are inversely proportional to Pd₂ Si thickness, and increase with anneal time and temperature. The results are compared to the known physical chemical interactions of Pd Si and Al. The studies demonstrate that by proper selection of process parameters and contact structure design, stable Al-Si contact resistance can be achieved for semiconductor device applications when Pd is used as an intermediate contact metallurgy.