Abstract Chemical wet etching technology is widely applied in semiconductor device fabrication such as the patterned sapphire substrates. However, the etching of pre-formed structure is still lack of investigations, which has potential applications in the preparation of particular devices. By using molten KOH etchant, the present work studied the wet etching behaviors of cavity on the A-plane of sapphire crystal in three-dimensional space and revealed the etching kinetics. It was demonstrated that the cavity will evolve into a complicate symmetric shape with multiple facet planes during etching. The width of the cavity is gradually expanded however the depth of the cavity is stable during etching, where the Arrhenius model was held, indicating that the etching process is realized by step flow removal of atoms. The present results improve the understanding of the morphology evolution and relevant kinetics of a pre-formed structure on sapphire crystal during wet etching, which shed further light on the single crystal wet etching technology for device fabrication.

中文翻译：

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热 KOH 蚀刻液中蓝宝石晶体 A 面的空腔蚀刻演变

摘要 化学湿法刻蚀技术广泛应用于半导体器件制造，如图案化蓝宝石衬底。然而，预成型结构的蚀刻仍然缺乏研究，这在特定器件的制备中具有潜在的应用。本工作通过使用熔融 KOH 蚀刻剂，在三维空间中研究了空腔在蓝宝石晶体 A 平面上的湿蚀刻行为，并揭示了蚀刻动力学。结果表明，在蚀刻过程中，腔体将演变成具有多个小平面的复杂对称形状。空腔的宽度逐渐扩大，但在蚀刻过程中空腔的深度是稳定的，其中保留了 Arrhenius 模型，表明蚀刻过程是通过原子的逐步流动去除来实现的。