Numerical Analysis Of Thermal Effect Of Single Crystal Silicon By Combined Laser

A nanosecond pulse laser and a millisecond long pulse laser are combined in order to improve the coupling efficiency of single crystal silicon material in laser processing. The effects of the change of the two laser beam and the delay time of the combined laser is studied, and the optimized time delay is obtained.Based on thermal elastic-plastic theory, a two-dimensional axisymmetric finite element of combined laser irradiation of silicon is established. The coupling efficiency of laser can be improved through the analysis of the temperature and stress field. The influence of laser energy density and ns laser energy on combined laser is studied in this paper. We find that when the millisecond laser energy density is lower, the effect of combined laser is more obvious. And with the increase of millisecond laser energy density, the effect becomes worse. In a certain range, the increase of the ns laser energy can improve the effect of the combined laser. Finally we measure the damage morphology of single crystal silicon with different laser energy density, and the results is in good agreement with the numerical calculation results.The effects of different pulse delay time on the effect of combined laser is studied by using finite element method. The optimal delay time is obtained by numerical calculation. Further study of the influence of millisecond laser energy density and ns lase energy on the optimal delay time. The results show that:with the increase of the millisecond laser energy density or ns laser energy the optimal delay time will decrease.The research of this paper can provide a theoretical and experimental basis for the study of combined laser.