脉冲激光对单晶硅打孔的研究

采用波长为1064 nm的重复脉冲激光对单晶硅进行打孔实验,观测了小孔烧蚀深度以及表面孔径大小随脉冲个数的变化规律,并对激光辐照单晶硅的热力学过程进行了理论分析。研究结果表明:入射激光在穿过等离子体到达单晶硅的表面时,光斑尺寸会有所增大,小孔孔径会大于聚焦光束尺寸。小孔内的等离子体本身具有很高的温度,高温等离子体在膨胀过程中会通过热辐射和热传导等过程向小孔周围传递热量,这也会对小孔孔径起到一定的拓展作用。当脉冲个数低于6个时,孔深随入射脉冲个数的增加近似线性增长,而后开始缓慢增长直至保持不变,这主要是由激光等离子体屏蔽效应决定的。

Research on drilling hole of single crystal by pulse laser

The laser drilling holes processing experiment was conducted on the silicon under the radiation of a 1064 nm nanosecond repetitive pulse laser. Variation rule of holes' diameter transferring with laser pulse number and the depth of the holes could be both observed through this experiment. Meanwhile it analyzed the thermodynamic process of pulse laser irradiating silicon as well. The result shows that being confined by the narrow hole, the hot plasma expands rapidly inside the channel. It transmits a large fraction of its energy to the hole walls by radiative and convective heat transport, thereby contributing to the radial expansion of the hole. The hole depth growth rate have linear increase with pulse number when the pulse number is under 6, after that it becomes slower and slower until remain stable, which is mainly due to plasma shielding effect.