Dwell-time related effects in focused ion beam synthesis of cobalt disilicide

The influence of the high current density of a focused ion beam on the ion beam synthesis of CoSi2 layers has been investigated. After 35 keV Co+ or 70 keV Co2+ implantation into a heated Si(111) substrate and subsequent annealing, the layers have been investigated by scanning electron microscopy and Rutherford backscattering spectroscopy (RBS). It is shown that the mode of beam scanning influences the CoSi2 layer formation significantly. At a given substrate temperature, a sufficient low dwell time is required to obtain a continuous layer rather than a laterally disrupted structure. With increasing target temperature, the dwell-time window becomes less restricted. The results are discussed in terms of damaging and dynamic annealing of the silicon crystal. RBS channeling investigations demonstrate that continuous or disrupted CoSi2 layers are formed when the substrate remains crystalline or becomes amorphous, respectively.