皮 秒 激 光 扫 描 硅 材 料 微 孔 自 成 形 行 为 及 机 理 研 究

Scanning silicon surface with a picosecond laser with pulse width of 10 ps, frequency of 200 kHz and wavelength of 1064 nm will self-form microhole structure. By changing pulse energy density, scanning speed and scanning times, the evolution law of microhole is studied experimentally. The results show that the influence of different parameters on microholes can be summarized as pulse energy density and effective pulse number per unit area. With the increase of pulse energy density, the microholes gradually move to both sides of the groove, from the initial random arrangement to the one-dimensional linear uniform arrangement. With the increase of effective pulse number per unit area, the number of microholes on both sides of the edge changes from less to more, and the size changes from small to large, and finally microholes disappear. By simulating the temperature field, the change of phase transition and surface tension of materials at different temperatures was analyzed. It was found that liquid silicon solidified under the drive of surface tension to form protrusions, which led to uneven deposition of laser energy and finally formed microholes. This indicates that the physical mechanism of microhole self-forming is the combined action of laser-induced material phase transformation and Marangoni effect.