Microscale patterning of semiconductor c-Si by selective laser-heating induced KOH etching
Microscale patterning of semiconductor c-Si by selective laser-heating induced KOH etching
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DOI：
10.1088/1361-6641/ac09d1
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发表时间：
2021
影响因子：
1.9
通讯作者：
Arpan Sinha;M. Gupta
中科院分区：
文献类型：
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作者：
Arpan Sinha;M. Gupta
激光图案化已经用于半导体器件（如太阳能电池、光电探测器、LED）的微尺度制造，并且由于其图案化灵活性、空间分辨率和无掩模操作优于复杂的常规光刻的若干优点，还用于表面的润湿性、反射颜色、初始细菌粘附等的改性。目前，激光诱导烧蚀是硅太阳能电池制造中有前途的图案化方法;然而，激光诱导的缺陷和热应力仍然是一个重要的问题。在本文中，我们展示了一种用于图案化c-Si的无激光烧蚀方法，该方法基于以下观察：KOH对c-Si的各向异性蚀刻高度依赖于温度，因为与室温相比，在80 °C下的蚀刻速率快约100倍。晶体硅的激光加热诱导化学蚀刻（LHICE）可以通过在硅衬底上的局部区域上提供必要的低温来帮助减轻这种激光诱导的损伤。我们研究了微秒级脉冲激光辅助化学刻蚀c-Si衬底的微尺度图案，并表明，激光诱导的损伤可以消除所示的少数载流子寿命的保存。我们还提出了激光加工参数，如激光功率，扫描速度和占空比对蚀刻深度和表面形貌的影响的结果。光学，表面形貌，深度分布，和LCPSim模拟结果也被提出来优化和理解LHICE过程。这种温度选择性化学蚀刻的通用方法可以应用于各种器件制造中使用的各种薄膜和块体材料。
Laser patterning has been used for the micro-scale fabrication of semiconductor devices like solar cells, photodetectors, LEDs, and also for modification of surfaces for wettability, reflected colors, initial bacterial adhesion, etc, due to its several advantages of patterning flexibility, spatial resolution, and mask-free operation over complex conventional lithography. Currently, laser-induced ablation is a promising patterning method in silicon solar cell fabrication; however, laser-induced defects, and thermal stresses remain a significant concern. In this paper, we demonstrate a laser ablation-free method for patterning c-Si based on the observation that the anisotropic etching of c-Si by KOH is highly temperature-dependent as the etching rate is about 100 times faster at 80 °C compared to room temperature. The laser heating-induced chemical etching (LHICE) of crystalline silicon can help alleviate such laser-induced damage by providing the necessary low temperature on the localized area(s) on the silicon substrate. We investigated the micro-second pulsed laser-assisted chemical etching of c-Si substrate for microscale patterning and showed that laser-induced damage could be eliminated as indicated by the minority carrier lifetime preservation. We also present results of the effect of laser processing parameters such as laser power, scan speed, and duty cycle on etching depth and surface morphology. The optical, surface morphology, depth profile, and LCPSim simulation results are also presented to optimize and understand the LHICE process. This versatile methodology of temperature-selective chemical etching could be applied to various thin-film and bulk materials used in diverse device fabrication.