Study on controllable surface morphology of the micro-pattern fabricated on metallic foil by laser shock imprinting

Laser shock imprinting was an advanced micro/nanostructure forming method, and had great potential application in Micro Electro Mechanical Systems (MEMS) and optoelectronic devices. However, the residual rough structure and micro defects on imprinted micro-pattern limited the industrial application of laser shock imprinting. In the study, the laser pre-shocked aluminum foil was introduced for fabricating ultrasmooth micro-pattern with high mechanical properties. The effect of laser pulse energy and overlap ratio on the micro-pattern imprinting was characterized by 3D morphology and deformation depth. The local morphology and nanoindentation of micro-pattern on different locations were also investigated to reveal robustness of roughness and mechanical properties. The experimental results indicated that the morphology and mechanical properties of micro-pattern on laser pre-shocked aluminum foil were greatly improved than that of on original aluminum foil. The laser pulse energy and overlap ratio had great influence on forming depth, and the morphology and mechanical properties of micro-pattern groove were better than that of the micro-pattern center. The hardness and roughness on micro-pattern groove were changed obviously (the hardness increased about 10% and the average roughness decreased to 4 nm). The laser pre-shock imprinting physics mechanism was evaluated by finite element modeling. The presented study demonstrated that appropriate laser shock imprinting parameter can realize to fabricate ultrasmooth, precise, controllable, and high mechanical properties micro-pattern on laser pre-shocked aluminum foil.