Growth of WSi₂ in phosphorous-implanted W/«Si» couples

The thermal reaction of rf-sputter-deposited tungsten films with a (100) silicon substrate is investigated by vacuum furnace annealing and rapid thermal annealing. An irradiation of the W/Si interface by a phosphorous ion beam at room temperature prior to annealing promotes a uniform interfacial growth of WSi₂. The growth of WSi₂ follows diffusion-controlled kinetics during both furnace annealing and rapid thermal processing. A growth law of x² = kt is obtained for furnace annealing between 690 and 740° C, where x is the thickness of the compound, t is the annealing duration after an initial incubation period and k = 62 (cm²/s) exp (--3.0 eV/kT). The surface smoothness of the suicide films improves with increasing ion dose.