Laser annealing for solid-phase thin-film reactions

Abstract

We propose a scheme for calculating the amount of thin‐film reaction as a result of the pulsed annealing induced by laser irradiation. Under ideal conditions, simple analytical solutions are obtained for reaction temperature T (t) if the absorbed laser power P (t) is a step, linear, or polynomial function of t. The thickness of the reacted film is equivalent to that of a thermal (furnace) annealing at an effective temperature T_eff for an effective annealing time Δt_eff. T_eff is the peak value of T (t) and Δt_eff ≃ (kT_eff/E_a)^mΔt, where m=1 or 1/2 [determined by the function form of T (t) near T_eff], E_a is the activation energy of the process, and Δt is the duration of the laser pulse. The present results can also be used as an approximation in some cases of the laser annealing of ion‐implanted semiconductors. Effect of antireflective coatings is thus predicted. Preliminary experimental results on the laser annealing for metal‐silicide formation are discussed and are compared with the present calculation.