Reduction of Dichlorosilane-Based Tungsten Silicide Resistivity by Amorphization and Its Applicability as an Electrode

Abstract

The impact of ion implantation on dichlorosilane-based tungsten silicide is reported with an emphasis on structural changes and the formation of low-resistivity silicide. It was found that implantation to the as-deposited dichlorosilane-based tungsten layer with the hexagonal close-packed structure resulted in amorphization. After thermal annealing for crystallization, the amorphized silicide was converted to the large-grain-sized tetragonal structure in which the resistivity of the silicide was about 30% lower than that of the conventional structure. In addition, the surface of the implanted silicide was smoother than that of the conventional one. The resistivity after thermal activation depended on the implantation conditions: implantation species, energy, and dose. Among all implantation species tested, phosophorus ions were found to be the most effective in terms of device fabrication. For optimized device performance, the energy should be controlled to contain the ions in the silicide. With this condition, device performance was not adversely affected, and line resistance and dopant depletion were improved.