Abstract : The objective of this thesis is the elaboration of polycrystalline silicon, on borosilicate glass substrate, by a Continuous Wave laser annealing of amorphous silicon operating in the liquid phase regime. Numerical simulations of the laser-amorphous silicon interaction have been carried out using COMSOL tool. We were able to monitor the evolution of the heat transfer in the different laser irradiated Si/glass structures. Thus, we have evaluated the effects of experimental parameters such as the scan speed, the laser power, the substrate temperature on the phase transition thresholds (melting, crystallization, evaporation). The modeling data were compared to the experimental data obtained on laser irradiated amorphous Si films, and the results were thoroughly discussed. In a second part, we have investigated the structural and morphological properties of polysilicon films prepared by CW laser irradiation of different amorphous silicon. We have shown that the presence of impurities such as hydrogen or argon in the amorphous silicon affects strongly the quality of the formed polysilicon film. We also found that the Si crystal growth occurs epitaxially from lateral and longitudinal thermal gradient produced respectively by the laser beam profile and thermal conduction, and by thermal convection in the scanning direction. The optimization of the experimental procedure led to the formation of polysilicon films with large grains up to several hundred microns long and tens microns in width. Such materials are of great interest to electronic and photovoltaic devices.