Non-damage deep etching of SiC by hybrid laser-high temperature chemical processing

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 x 10(9) W/cm(2) 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.