脉冲绿激光划切蓝宝石基片过程研究

Study on Scribing of Sapphire Substrate by Pulsed Green Laser Irradiation

采用波长为532nm的脉冲绿激光对蓝宝石基片进行划切加工。首先研究单脉冲激光烧蚀加工蓝宝石材料,确定材料烧蚀阈值和产生裂纹阈值,分析激光能量密度与烧蚀凹坑深度和直径之间的关系,接着对纳秒绿激光烧蚀蓝宝石基片的热应力进行了分析,最后进行脉冲激光划切蓝宝石的工艺实验。研究结果表明:纳秒绿激光烧蚀蓝宝石材料主要是基于光热作用的机理。光热作用使得蓝宝石材料熔化、汽化,为材料去除提供条件,过大的热应力导致材料产生裂纹。综合考虑激光划切工艺参数(能量密度、扫描速度、扫描次数)以及材料表面处理方式等因素,获得了切槽宽度为20μm,深宽比为7的良好切槽。

A pulsed green laser with wavelength of 532 nm is employed to scribe the sapphire sabstrate. Firstl;y, sapphire surface ablated by single pulsed laser is observed. The ablation threshold and the cracks threshold of sapphire are identified. The relationship between the laser fluence and crater depth/diameter is analyzed. Then, the thermal stress of nanosecond green laser irradiating sapphire is analyzed. Finally, the parametric laser scribing of sapphire substrate is conducted. The results show that the formation of the craters and grooves in the laser ablation process is mainly due to the photothermal effect. The effect results in melting, vaporization, which is essential to the material removal. Meanwhile, micro-cracks are easily induced by the larger thermal stress. A narrow groove width of 20 μm, aspect ratio of 7 and better processing quality can be obtained simultaneously by considering laser processing parameters （laser fluence, scanning velocity and scanning times） and the treatment of the material surface.