SiC is considered as preferred material for micro‐electro‐mechanical system in the future. The excellent mechanical property and chemical stability make it difficult to perform deep etching. The hybrid laser‐high temperature chemical etching is investigated to realize non‐damage deep etching of SiC. The influences of defocus, laser pulse interval, laser intensity, and pulse number on etching depth are researched. The optimized laser parameter for SiC non‐damage deep etching is laser intensity of 10 × 109 W/cm2 with a pulse interval of 10 ms. In order to analyze the interaction mechanism, the temperature field and laser‐induced liquid jet in the liquid environment are calculated numerically. It is concluded that the material removal mechanism consists of laser heating vaporization during laser pulse, mechanical effect of laser‐induced liquid jet impact between two adjacent laser pulses and chemical etching in laser‐induced local high‐temperature environment. The chemical reaction between SiC and mixture of HF, and HNO3 solution produces gases and fluosilicic acid and effectively reduces the roughness of the modified layer making the surface smoother, and also removes the microcracks on the side wall of the etched region.
.To compare the processing efficiency and quality of 20- to 1000-Hz pulsed laser and continuous laser ablating single-crystal germanium wafers, experiments and numerical simulations were performed. The experiments were conducted by varying the duty cycle and repetition frequency of a pulsed laser to ablate single-crystal germanium with the same total laser energy and irradiation time of 100 ms, and comparing the temperature-rise profile during ablation and the damage morphology after ablation. The temperature-rise curves during the ablation and the damage morphologies after the ablation were compared. Numerical simulations were performed to compute the dislocation field of single-crystal germanium ablated by laser with different parameters to compare the size of the heat-affected zone (HAZ) formed on the sample surface after the laser ablation with different parameters. The results show that the sample surface has the largest ablated pore size and the smallest HAZ after ablation at a laser repetition frequency of 20 Hz and a duty cycle of 5%; the smallest pore size and the largest HAZ after ablation at a laser repetition frequency of 1000 Hz and a duty cycle of 50%, and the continuous laser results are in the middle.
The thermal stress damage process of 1080 nm laser ablation of single crystal germanium was recorded in real time using a high-speed CCD. A three-dimensional finite element numerical model based on Fourier's heat conduction equation, Hooke's law and Alexander Hasson equation was developed to analyze the thermal stress damage mechanism involved. The damage morphology of the ablated samples was observed using an optical microscope. The results show that the cooling process has an important influence on the fracture in the laser irradiated region of single crystal germanium. The fracture is the result of a combination of thermal stress and local yield strength reduction.
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