Low temperature formation of NiSi2 from evaporated silicon

2 MeV 4He+ backscattering spectrometry and CuK/sub α/ X-ray diffraction are used to study NiSi2 formed by thermal annealing from NiSi and evaporated Si. Uniform layers of NiSi2 are formed at temperatures between 350 and 425 0C. The thickness of NiSi2 formed is proportional to the square root of time at a fixed temperature. This indicates that the growth of NiSi2 from evaporated Si is a diffusion-controlled process. The activation energy of this reaction is about 1.65 eV, which is larger than that of regrowth of ion-implanted NiSi2 and those of thermal Ni2Si and NiSi formation. The diffusion-controlled process in this case is different from the known result that on single crystal Si the formation of NiSi2 is nucleation-controlled. The dominant moving species in the present NiSi2 formation is Ni, which is identified by implanted Xe or 18O markers initially located inside the Si. (author)