COBALT SILICIDE FORMATION CAUSED BY ARSENIC ION-BEAM MIXING AND RAPID THERMAL ANNEALING

Ion beam mixing and rapid thermal annealing (RTA) were used to prepare low resistivity (almost-equal-to 23-mu-OMEGA-cm) cobalt disilicide, CoSi2, layers. Through-metal As+ ion implantation causes some mixing between Co and Si resulting in the formation of cobalt silicides. By using RTA, the silicide formation happens in the phase sequence Co2Si, CoSi and CoSi2. Samples which were only subjected to a one-step high temperature RTA process (T greater-than-or-equal-to 900-degrees-C, 1 s) show significant lateral growth of cobalt silicides. By ion beam mixing of Co and Si this lateral silicide growth could be reduced efficiently. Furthermore one can get a very homogeneous CoSi2 layer.