Proceedings Article | 16 January 2006
Jianfeng Cui, Jing Zhao, Zhongwei Fan, Cunhua Zhao, Yong Bi, Jing Zhang, Gang Niu, Zhaohui Shi, Bo Pei, Guoxin Zhang, Yan Xue, Yan Qi
Proc. SPIE. 6028, ICO20: Lasers and Laser Technologies
KEYWORDS: Monochromatic aberrations, Crystals, Silicon, Laser applications, Nd:YAG lasers, Semiconductor lasers, Thermal effects, Laser cutting, Semiconducting wafers, Laser systems engineering
The theory of laser cutter and the technology neck is analyzed. We can conclude that it is almost impossible to deal with the waste thick silicon wafers which are yielded in producing silicon wafers by conventional eroding or diamond cutting, while it is also unperfected with ecumenical laser cutter without good beam quality or precise laser and optics system. It is represented that high average power and high repetition rate laser with good beam quality and precise laser and optics system are pivotal to obtain excellent cutting effect such as thick groove depth, rapid cutting speed, fine kerf section without considering the effect of technique. Considering laser medium thermal lens effect and thermal focal length changing with pumping power, using plano-convex high reflectivity mirror as the back cavity mirror to compensate the heat lens influence, aλ/4 waveplate to compensate heat-induced birefraction, utilize the Nd:YAG self-aperture effect, more than 50 W average power 1.064 um IR output is obtained with beam quality factor (M2) equals 3.19. Through the LD-Pumped Nd:YAG laser cutter we developed with short focus length negative spherical aberration focusing lens, double axis linear step motor positioning system, suitable beam expander multiplying factor, appropriate diameter of exit beam aperture, proper repetition rate, when the cutting velocity equals 400mm/min, 0.75mm thick silicon wafer can be penetrated; when the cutting velocity equals 100mm/min, double-layer 0.75mm thick silicon wafer can be penetrated. The cross section is fine and the groove is narrow, the cutting quality meets the expecting demand.
