Study On Metal Film Micro Hole Processing Based On Femtosecond Laser Precise Micromaching Technology

Femtosecond laser is well known to us for its ultra-short duration and extremely high peak power, which makes it has some incomparable advantages in microfabrication compared to traditional laser. The mechanism of interacts between femtosecond laser and materials is always the hot spot of lots of scientific research. Because of its ultra-short duration traditional heat conduction equation is unavailable under such a high non-equilibrium state. This thesis studied the femtosecond laser interaction with metal by ablation and drilling experiments as well as the two-temperature model stimulation which also serve as theoretical basis for micromachining.In the simulation, by using the experimental fact and the sample parameter, the electron and lattice temperature distributions were stimulated by one-dimension two-temperature model. The physical picture described by modeling agreed well with theoretical mechanism. Moreover, taking the Gaussian distributions both in time-domain and in space into consideration, 2D two-temperature model was established to calculate the relationship between ablated spot size and injected pulse energy. The numerical results showed a good match with experimental results. Furthermore, under some assumptions, the 3D two-temperature model was introduced. By single-pulse 3D two-temperature model time and spatial evolution of both metal lattice and electron were obtained. The 3D shape of ablation hole was also simulated .The relation between pulse energy and the depth of the hole was got and threshold ablation fluence was calculated. By multi-pulse 3D two-temperature model the relation between the depth and diameter of the ablation hole ant pulse number was gotten.In the metal ablation experiment, diameters of ablation holes by pulses with different numbers and energy were measured. The threshold ablated fluence for aluminum of different pulse numbers was calculated. The influence of ablated spot size and depth by pulse number as well as pulse energy was also analyzed qualitatively. In the experimental investigation of drilling of hole with large aspect ratios in mental, the distortion of exit caused by the polarization direction of incident beam was shown and interpreted. An optimization method was proposed after that and it achieved a good result.