Thermal stress cleavage of a single-crystal round sapphire bar by carbon dioxide laser
Thermal stress cleavage of a single-crystal round sapphire bar by carbon dioxide laser
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DOI：
10.1016/j.jmatprotec.2021.117237
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发表时间：
2021
影响因子：
6.3
通讯作者：
T. Furumoto;Ryuya Saito;Kota Watanabe;Yuzo Ochi;Y. Hashimoto;M. Yamaguchi;T. Koyano;A. Hosokawa
中科院分区：
文献类型：
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作者：
T. Furumoto;Ryuya Saito;Kota Watanabe;Yuzo Ochi;Y. Hashimoto;M. Yamaguchi;T. Koyano;A. Hosokawa
本研究首次尝试将热应力劈裂应用于具有形态连续圆周表面的单晶圆蓝宝石棒。以前，由于热应力分布引起的裂纹扩展行为，热应力劈裂仅应用于脆性材料基底或晶片。为了克服这个问题，在圆周上制备V形凹槽作为裂纹扩展的起始点，并使用连续波二氧化碳（CO2）激光器作为热源。通过有限元分析模拟了热应力行为，并评估了初始裂纹形态对热应力行为的影响。此外，使用声发射传感器监测裂纹扩展，并研究了圆蓝宝石棒的分离机制。结果表明，使用CO2激光束的热应力劈裂使圆形蓝宝石棒与V形凹槽完全分离，而不留下任何最终边缘。裂纹扩展行为是由裂纹扩展过程中的热应力分布和形貌变化之间的关系确定的。所制造的尖锐的V形凹槽改善了解理表面的质量，并且凹槽的高纵横比能够实现高质量的解理。在激光束照射开始后立即开始的初始裂纹扩展受到V形槽的尖端的影响，并且裂纹扩展方向可以通过V形槽的尖端形态来控制。
This study is the first attempt of applying thermal stress cleavage to a single-crystal round sapphire bar having a morphologically continuous circumference surface. Previously, thermal stress cleavage was only applied to brittle material substrates or wafers owing to the crack propagation behaviour induced by thermal stress distribution. To overcome this issue, a V-shaped groove was prepared on the circumference as an initial point for crack propagation, and a continuous-wave carbon dioxide (CO2) laser was used as the heat source. The thermal stress behaviour was simulated via finite element analysis, and the effect of the initial crack morphology on the thermal stress behaviour was evaluated. In addition, the crack propagation was monitored using an acoustic emission sensor, and the separation mechanism of the round sapphire bar was investigated. Results indicated that the thermal stress cleavage using the CO2laser beam allowed the complete separation of the round sapphire bar with the V-shaped groove without any final edge remaining. The crack propagation behaviour was determined from the relationship between the thermal stress distribution and morphology change during crack propagation. The fabricated sharp V-shaped groove improved the quality of the cleaved surface, and the high aspect ratio of the groove enabled a high-quality cleavage. The initial crack propagation immediately after the start of laser beam irradiation was affected by the tip of the V-shaped groove, and the crack propagation direction could be controlled through the tip morphology of the V-shaped groove.