Lu Han, Zhang Hua, Jin Mingliang, He Tao, Zhou Guofu, Shui Lingling
Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China.
Micromachines (Basel). 2016 Jan 25;7(2):19. doi: 10.3390/mi7020019.
Anisotropic etching of silicon in potassium hydroxide (KOH) is an important technology in micromachining. The residue deposition from KOH etching of Si is typically regarded as a disadvantage of this technology. In this report, we make use of this residue as a second masking layer to fabricate two-layer complex structures. Square patterns with size in the range of 15⁻150 μm and gap distance of 5 μm have been designed and tested. The residue masking layer appears when the substrate is over-etched in hydrofluoric acid (HF) solution over a threshold. The two-layer structures of micropyramids surrounded by wall-like structures are obtained according to the two different masking layers of SiO₂ and residue. The residue masking layer is stable and can survive over KOH etching for long time to achieve deep Si etching. The process parameters of etchant concentration, temperature, etching time and pattern size have been investigated. With well-controlled two-layer structures, useful structures could be designed for applications in plasmonic and microfluidic devices in the future.
在氢氧化钾（KOH）中对硅进行各向异性蚀刻是微加工中的一项重要技术。硅在KOH蚀刻过程中产生的残留沉积物通常被视为该技术的一个缺点。在本报告中，我们利用这种残留物作为第二掩膜层来制造两层复杂结构。设计并测试了尺寸范围为15⁻150μm且间隙距离为5μm的方形图案。当衬底在氢氟酸（HF）溶液中蚀刻超过阈值时，会出现残留掩膜层。根据SiO₂和残留物这两种不同的掩膜层，获得了由壁状结构包围的微金字塔两层结构。残留掩膜层很稳定，能够在KOH蚀刻过程中长时间留存以实现硅的深度蚀刻。研究了蚀刻剂浓度、温度、蚀刻时间和图案尺寸等工艺参数。通过良好控制的两层结构，未来可为等离子体和微流体器件的应用设计出有用的结构。
