title: A novel fabrication method of silicon nano-needles using MEMS TMAH etching techniques.
abstract: Nano-needles play important roles in nanoscale operations. However, current nano-needle fabrication is usually expensive and controling the sizes and angles is complicated. We have developed a simple and low cost silicon nano-needle fabrication method using traditional microelectromechanical system (MEMS) tetramethyl ammonium hydroxide (TMAH) etching techniques. We take advantage of the fact that the decrease of the silicon etch rate in TMAH solutions exhibits an inverse fourth power dependence on the boron doping concentration in our nano-needle fabrication. Silicon nano-needles, with high aspect ratio and sharp angles θ as small as 2.9°, are obtained, which could be used for bio-sensors and nano-handling procedures, such as penetrating living cells. An analytic model is proposed to explain the etching evolution of the experimental results, which is used to predict the needle angle, length, and etching time. Based on our method, nano-needles with small acute angle θ can be obtained.
authors.affiliation: Department of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Sheping
authors.initials: S
authors.lastname: Yan
authors.forename: Yang
authors.initials: Y
authors.lastname: Xu
authors.forename: Junyi
authors.initials: J
authors.lastname: Yang
authors.forename: Huiquan
authors.initials: H
authors.lastname: Wang
authors.forename: Zhonghe
authors.initials: Z
authors.lastname: Jin
authors.forename: Yuelin
authors.initials: Y
authors.lastname: Wang
mesh_terms: D004867:Equipment Design; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation / Q000379:methods*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*
chemical_list: D000644:Quaternary Ammonium Compounds; C027917:tetramethylammonium; D012825:Silicon