Etching Mechanism Behind the High-Speed Etching of Silicon in NH2OH-added Alkaline Solutions

カテゴリ: 論文誌(論文単位)

グループ名: 【E】センサ・マイクロマシン部門

発行日: 2020/01/01

タイトル(英語): Etching Mechanism Behind the High-Speed Etching of Silicon in NH2OH-added Alkaline Solutions

著者名: Veerla Swarnalatha (MEMS and Micro/Nano Systems Laboratory, Department of Physics Indian Institute of Technology Hyderabad), Kanneri Thettiyappath Vismaya (MEMS and Micro/Nano Systems Laboratory, Department of Physics Indian Institute of Technology Hydera

著者名(英語): Veerla Swarnalatha (MEMS and Micro/Nano Systems Laboratory, Department of Physics Indian Institute of Technology Hyderabad), Kanneri Thettiyappath Vismaya (MEMS and Micro/Nano Systems Laboratory, Department of Physics Indian Institute of Technology Hyderabad), Avvaru Venkata Narasimha Rao (MEMS and Micro/Nano Systems Laboratory, Department of Physics Indian Institute of Technology Hyderabad), Prem Pal (MEMS and Micro/Nano Systems Laboratory, Department of Physics Indian Institute of Technology Hyderabad), Ashok Kumar Pandey (Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad), Hiroshi Tanaka (Department of Mechanical Engineering, Aichi Institute of Technology), Kazuo Sato (Department of Mechanical Engineering, Aichi Institute of Technology)

キーワード: silicon，wet bulk micromachining，KOH，TMAH，wet anisotropic etching

要約(英語): Anisotropic wet bulk micromachining is one of the main techniques used in microelectromechanical systems to fabricate microstructures that have applications in sensors and actuators. Potassium-hydroxide-based and tetramethylammonium-hydroxide-based solutions are the most commonly used wet anisotropic etchants. However, the etch rate attainable using these conventional etchants is limited and, hence, affects industrial productivity. Alkaline solutions with some additives show improved etching characteristics. The addition of NH2OH to pure alkaline etchant solutions increases etch rate significantly. The etch depth attained per unit time is more in these modified solutions compared with pure alkaline solutions. This can be exploited to make microstructures with low fabrication time and high productivity. In this work, a simple etching mechanism is proposed to explain silicon wet anisotropic etching in NH2OH-added alkaline solutions. The mechanism is based on a two-step etching process: (i) oxidation and (ii) removal of Si atoms by water molecules. The initial oxidation step has two possible pathways: chemical and electrochemical oxidation. In the presence of alkaline solutions, NH2OH gives NH2O- ions and H2O molecules. Thus, NH2O- ions, OH- ions, and H2O molecules are the reactive species in the modified etchant solution. The aim of this work is to elucidate the detailed reaction mechanism in NH2OH-added alkaline solution and highlight the reason behind the enhanced etch rate.

本誌: 電気学会論文誌E（センサ・マイクロマシン部門誌） Vol.140 No.1 （2020） 特集：センサ・マイクロマシン英文特集号

本誌掲載ページ: 24-30 p

原稿種別: 論文／英語

電子版へのリンク: https://www.jstage.jst.go.jp/article/ieejsmas/140/1/140_24/_article/-char/ja/