J. Micro/Nanolith. MEMS MOEMS 14(2), 024502
http://nanolithography.spiedigitallibrary.org/article.aspx?articleid=2362375
Ji Fan,a,b Wen Ting Zhang,a Jin Quan Liu,a Wen Jie Wu,a Tao Zhu,a and Liang Cheng Tua,b,*
a Huazhong University of Science and Technology, School of Physics, MOE Key Laboratory of Fundamental Physical Quantities Measurement,
Wuhan 430074, China
b Huazhong University of Science and Technology, Institute of Geophysics, Wuhan 430074, China
Abstract. We systematically investigate the fabrication and dry-release technology for a high aspect ratio (HAR) structure with vertical and smooth silicon etching sidewalls. One-hundred-micrometer silicon on insulator (SOI) wafers are used in this work. By optimizing the process parameters of inductively coupled plasma deep reactiveion etching, a HAR (∼25∶1) structure with a microtrench width of 4 μm has been demonstrated. A perfect etching profile has been obtained in which the structures present an almost perfect verticality of 0.10 μm and no sidewall scallops. The root-mean square roughness of silicon sidewalls is 20 to 29 nm. An in situ dry-release method using notching effect is employed after etching. By analysis, we found that the final notch length is typically an aspect-ratio-dependent process. The structure designed in this work has been successfully released by this in situ dry-release method, and the released bottom roughness effectively prohibits the stiction mechanism. The results demonstrate potential applications for design and fabrication of HAR SOI MEMS/MOEMS.
Keywords: high aspect ratio; inductively coupled plasma deep reactive-ion etching; vertical and smooth silicon sidewall etching;
dry-release.
© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.JMM.14.2.024502]
Paper 15035 received Apr. 3, 2015; accepted for publication May 28, 2015; published online Jun. 23, 2015.
