标题：Uniform Metal-Assisted Chemical Etching for Ultra-High-Aspect-Ratio Microstructures on Silicon
作者：Li, Liyi; Tuan, Chia-Chi; Zhang, Cheng; Chen, Yun; Lian, Gang; Wong, Ching-Ping
作者机构：[Li, Liyi; Tuan, Chia-Chi; Zhang, Cheng; Chen, Yun; Lian, Gang; Wong, Ching-Ping] Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.; 更多
通讯作者：Li, LY;Wong, CP;Wong, ChingPing
通讯作者地址：[Li, LY; Wong, CP]Georgia Inst Technol, Sch Mat Sci & Engn, Atlanta, GA 30332 USA.
来源：JOURNAL OF MICROELECTROMECHANICAL SYSTEMS
关键词：Metal-assisted chemical etching; silicon wet etch; high aspect ratio
摘要：Recently, uniform metal-assisted chemical etching (UMaCE) has been demonstrated as an effective wet etch method for fabrication of deep trenches and holes on silicon (Si). However, attempts to achieve higher aspect ratio by UMaCE was not successful because etching in random directions was observed. In this paper, the etching uniformity in UMaCE is systematically studied at different etching solution composition and catalyst configuration. The surface chemistry evolution of Si during etching is characterized by X-ray photoelectron spectroscopy, water contact angle, and electrical impedance spectroscopy. Based on the data, the reaction kinetics is analyzed, which shows that an electropolishing-type charge transport and a higher amount of oxide species on Si surface help mitigate the random etching behavior and effectively promote the aspect ratio of the etching with uniformity. Under the rationalized condition, uniform trenches with width of 2 mu m and aspect ratio of 120:1 is successfully fabricated by UMaCE.