SIMULATION OF TEMPERATURE AND ELASTIC FIELDS AND PHASE-TRANSITIONS IN SOI STRUCTURES FORMED BY PULSE HEATING

A two-dimensional model is developed of silicon recrystallization by nanosecond laser pulses in a silicon-on-insulator (SOI) structure with seed windows. Using this model, temperature and thermoelastic fields and phase transition behaviour are calculated. Phase transitions are described by new phase nucleation (homo- and heterogeneous) kinetics and its growth. The experimental situation is computerized using ruby laser action with 30 ns pulses and 0 to 3 J/cm2 energy density. The melting depth is shown to be greater at the edge of the seed window than in its center. This causes Si lateral epitaxy, while in the seed area the polycrystal remains. It is predicted that in the crystallization front movement along the dielectric the slope towards the dielectric increases, and the more, the lower the preheating temperature of the sample is. The thermoelastic stresses in the SOI structure are calculated before melting and after cooling, and it is shown that with higher preheating, the residual stresses in the sample are higher. The results of the computations are compared with experimental data.