Study On Micro-morphology Of Semiconductor And Metal By High Power Laser Irradiation

The laser surface modification mainly uses the pulsed laser to react with the material surface to promote the change of the morphology and properties of the surface to achieve the modification of the surface properties of the material.It has the advantages of no mask,high efficiency,selectivity and position ability.Studying the ablation of semiconductor and metal materials by high-power lasers has important practical significance for material laser processing and micro-nanostructure synthesis.We used Nd:YAG high-power pumped Q-switched laser to perform high-power pulse ablation experiments on silicon,silicon carbide and zinc.Different surface topography was obtained by adjusting the conditions of atmosphere,pulse number and pulse power..The surface morphology formed by ablation was studied by SEM and EDS,and the physical mechanism of these morphology was analyzed.The main conclusions of the study are as follows:(1)We observed that under vacuum background,the laser surface ablation of the silicon surface formed a crater-like structure,and the structure was not observed under the atmospheric background.In the atmospheric background,most of the laser energy is destroyed by the atmosphere and is not obvious by the subsequent plasma absorption plasma shock wave effect.In a vacuum environment,the silicon surface interacts more strongly with the laser,and the plasma shock wave creates a crater-like structure.A large number of columnar structures are formed after irradiation of silicon carbide under low vacuum.The main reason is that silicon carbide has higher melting point and hardness than silicon,and the relative thermal conductivity is better,which leads to the influence of plasma after ablation.Small,the above columnar structure is formed.(2)In the atmospheric background,a circular molten region was formed on the surface of the laser ablated zinc material,and a large amount of wrinkles were accumulated on the surrounding side walls.In the low vacuum background,relatively regular grooves and sidewalls were formed around the circular molten region of the surface of the laser ablated zinc material.By comparison,it is found that zinc is easier to produce a regular peripheralregion in a low vacuum environment than in an atmospheric environment.This is mainly because in the atmospheric environment,when the pulsed laser is ablated,atmospheric plasma is easily formed,and the gas has an influence on the cooling and condensation process of the sidewall,resulting in the occurrence of irregular wrinkles.After the power of the pulsed laser is increased,there is a significant difference in the surface microstructure generated after ablation of the zinc target.This is mainly due to the nonlinear interaction of the laser beam with the hotter and denser plasma,resulting in a larger plasma pressure,which results in a more intense extrapolation of the sidewalls.(3)In the low pressure background,the zinc target was ablated by pulsed laser,and zinc oxide microspheres appeared on the sidewall of its central hole with the diameter about 1.5-7microns.As the number of ablation increases,the scale of zinc oxide microspheres continues to increase,and its chemical composition is getting closer to zinc oxide.The presence of a large number of micron-sized zinc oxide spheres has a coupling enhancement effect on subsequent lasers because a large number of zinc oxide spheres are inlaid with regular nano-scale hexagonal and pentagonal facets,which produces specular reflection on subsequent pulsed lasers.Phenomenon,the convergence enhancement effect is produced in the inner surface layer of the hole,which greatly increases the power density of subsequent laser ablation.