全光纤皮秒激光切割蓝宝石晶圆的实验研究

Dicing of Sapphire Wafer with All-Fiber Picosecond Laser

搭建了中心波长为1064nm的光纤激光器装置。全保偏光纤结构的锁模脉冲种子源结合选频单元和全光纤放大器,实现了重复频率连续可调、脉冲串中脉冲数可选、微焦量级单脉冲能量的皮秒激光输出。通过优化选取激光器的输出参数,对厚度为110μm的蓝宝石晶圆进行了切片。观察多种激光参数下切片后的微观形貌,发现单脉冲能量、脉冲串的脉冲数以及光束的光斑圆度会显著影响切割效果。在重复频率100kHz、脉冲串内7脉冲、光斑圆度大于97%、平均功率0.37 W、划切速度600mm/s时,芯片外观最佳,良品率高达99.58%。

An all-fiber ultrafast laser system was demonstrated by utilizing polarization-maintaining fibers and polarization-maintaining fiber components. The central wavelength of the system was 1064 nm. A passively mode-locked fiber laser, a pulse selector, and subsequent fiber amplifiers realized micro joule pulse energy with tunable repetition rate and alterable pulse number in a single pulse string. In addition, an application of this laser system was carried out on dicing of 110 μm thick sapphire wafer. Experimental results showed that the pulse energy, the pulse number in a single pulse string, and the beam quality significantly affected the ablation performance. Up to 99.58% yield rate was achieved by using 100 kHz repetition rate, 7 pulses in a pulse string, 97% beam circularity, 0.37 W average power, and 600 mm/s dicing speed.