Selective removal of micro-corrugation by anisotropic wet etching

Inagaki, N.; Sasaki, Hikaru; Shikida, Mitsuhiro; Sato, Kazuo

doi:10.1109/sensor.2009.5285710

Cited by 3 publications

(3 citation statements)

References 6 publications

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“…As discussed in the next paragraph, one source of strength decay is the stress concentration factor, which holds in those zones where surface discontinuities appear. In high aspect ratio DRIE Bosch process, problems and challenges regarding scalloping attenuation have been reported in various investigations [35][36][37][38][39][40], although the problem presented several difficulties.…”

Section: Introductionmentioning

confidence: 99%

Scalloping and Stress Concentration in DRIE-Manufactured Comb-Drives

et al. 2018

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In the last decades, microelectromechanical systems have been increasing their number of degrees of freedom and their structural complexity. Hence, most recently designed MEMSs have required higher mobility than in the past and higher structural strength and stability. In some applications, device thickness increased up to the order of tens (or hundred) of microns, which nowadays can be easily obtained by means of DRIE Bosch process. Unfortunately, scalloping introduces stress concentration regions in some parts of the structure. Stress concentration is a dangerous source of strength loss for the whole structure and for comb-drives actuators which may suffer from side pull-in. This paper presents an analytical approach to characterize stress concentrations in DRIE micro-machined MEMS. The method is based on the linear elasticity equations, the de Saint-Venant Principle, and the boundary value problem for the case of a torsional state of the beam. The results obtained by means of this theoretical method are then compared with those obtained by using two other methods: one based on finite difference discretization of the equations, and one based on finite element analysis (FEA). Finally, the new theoretical approach yields results which are in accordance with the known value of the stress concentration factor for asymptotically null radius notches.

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Section: Introductionmentioning

confidence: 99%

Scalloping and Stress Concentration in DRIE-Manufactured Comb-Drives

et al. 2018

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“…Isotropic etching, due to its uniform etching rate along all directions, is not suitable for removing corrugations on dry-etched vertical sidewalls. Wet anisotropic etching is also used for corrugation removal [24][25][26]. Sasaki et al used a wet etching process after DRIE to reduce the corrugation [24].…”

Section: Introductionmentioning

confidence: 99%

“…Yun et al fabricated the vertical optical plane of {1 1 1} Si using DRIE and 45 wt% KOH at 70 • C [25]. Shikida et al analyzed the corrugation removal mechanism by using the anisotropic etch rates in KOH [26]. They succeeded to remove microcorrugation by short-time (5 min) etching in 50 wt% KOH.…”

Section: Introductionmentioning

confidence: 99%

Study of surfactant-added TMAH for applications in DRIE and wet etching-based micromachining

Tang

Shikida

Sato

et al. 2010

J. Micromech. Microeng.

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In this paper, etching anisotropy is evaluated for a number of different crystallographic orientations of silicon in a 0.1 vol% Triton-X-100 added 25 wt% tetramethylammonium hydroxide (TMAH) solution using a silicon hemisphere. The research is primarily aimed at developing advanced applications of wet etching in microelectromechanical systems (MEMS). The etching process is carried out at different temperatures in the range of 61-81 • C. The etching results of silicon hemisphere and different shapes of three-dimensional structures in {1 0 0}-and {1 1 0}-Si surfaces are analyzed. Significantly important anisotropy, different from a traditional etchant (e.g. pure KOH and TMAH), is investigated to extend the applications of the wet etching process in silicon bulk micromachining. The similar etching behavior of exact and vicinal {1 1 0} and {1 1 1} planes in TMAH + Triton is utilized selectively to remove the scalloping from deep reactive-ion etching (DRIE) etched profiles. The direct application of the present research is demonstrated by fabricating a cylindrical lens with highly smooth etched surface finish. The smoothness of a micro-lens at different locations is measured qualitatively by a scanning electron microscope and quantitatively by an atomic force microscope. The present paper provides a simple and effective fabrication method of the silicon micro-lens for optical MEMS applications.

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Advanced Surfactant-Modified Wet Anisotropic Etching

Tang¹,

Sato²

2012

Microelectromechanical Systems and Devices

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Selective removal of micro-corrugation by anisotropic wet etching

Cited by 3 publications

References 6 publications

Scalloping and Stress Concentration in DRIE-Manufactured Comb-Drives

Scalloping and Stress Concentration in DRIE-Manufactured Comb-Drives

Study of surfactant-added TMAH for applications in DRIE and wet etching-based micromachining

Advanced Surfactant-Modified Wet Anisotropic Etching

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