The authors report on processing silicon with bursts of hundreds of subpicosecond pulses with an intraburst pulse repetition frequency of 0.86 GHz at 515 nm. They find that the burst-to-burst overlap is a key parameter in optimizing the ablation efficiency for the line scribing and milling processes, contrary to traditional nonburst ultrafast processes. A nanosecond laser reference experiment and the corresponding multiphase simulations demonstrate that this behavior is directly related to the hydrodynamic effects of the molten material generated during the laser processing. Exploring the hole and scribe morphology with scanning transmission electron microscopy and selective area electron diffraction yields a surprise: holes show no sign of a polycrystalline or amorphous heat affected zone, while scribed lines clearly do. The multiphase modeling provides a likely explanation—it is not “ablation cooling.”

中文翻译：

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具有 ~GHz 脉冲串的硅超快激光烧蚀

作者报告了使用数百个亚皮秒脉冲的突发处理硅，突发内脉冲重复频率为 515 nm 处的 0.86 GHz。他们发现，与传统的非突发超快工艺相反，突发与突发重叠是优化线划线和铣削工艺烧蚀效率的关键参数。纳秒激光参考实验和相应的多相模拟表明，这种行为与激光加工过程中产生的熔融材料的流体动力学效应直接相关。使用扫描透射电子显微镜和选择性区域电子衍射探索孔和划线形态会产生一个惊喜：孔没有显示出多晶或非晶热影响区的迹象，而划线显然有。