C49-C54 phase transition in nanometric titanium disilicide grains

The formation of single C49-TiSi2 grains embedded in a polycrystalline Si matrix has been studied in detail by means of in-situ sheet resistance, x-ray diffraction measurements, and energy filtered transmission electron microscopy characterization. The C49 clusters were obtained by starting from a 3 nm-Ti/40 nm-Si multilayer structure. After the C49 clusters formation, increasing the temperature in the 800-1100degreesC range, the first-order C49-C54 transition has been therefore investigated in a system without triple grains boundaries. At each temperature the C54 fraction initially increases with the annealing time until it reaches a maximum constant value within similar to80 s. The maximum value of the converted C54 fraction increases linearly with the annealing temperature in the studied range. The nucleation sites density in these samples is similar to2x10(11) cm(-2), several orders of magnitude higher than in continuous TiSi2 films, where this value is about 4x10(6) cm(-2).