Next Article in Journal
Mental Fatigue Monitoring Using a Wearable Transparent Eye Detection System
Next Article in Special Issue
Opto-Microfluidic Immunosensors: From Colorimetric to Plasmonic
Previous Article in Journal
Numerical Investigation of Cell Encapsulation for Multiplexing Diagnostic Assays Using Novel Centrifugal Microfluidic Emulsification and Separation Platform
Previous Article in Special Issue
Fluid Flow Shear Stress Stimulation on a Multiplex Microfluidic Device for Rat Bone Marrow Stromal Cell Differentiation Enhancement
Article Menu

Export Article

Open AccessArticle
Micromachines 2016, 7(2), 19;

Two-Layer Microstructures Fabricated by One-Step Anisotropic Wet Etching of Si in KOH Solution

Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China
This paper is an extended version of our paper published in the 5th International Conference on Optofluidics 2015, Taipei, Taiwan, 26–29 July 2015.
Authors to whom correspondence should be addressed.
Academic Editors: Shih-Kang Fan, Da-Jeng Yao and Yi-Chung Tung
Received: 1 December 2015 / Revised: 16 January 2016 / Accepted: 18 January 2016 / Published: 25 January 2016
(This article belongs to the Special Issue Optofluidics 2015)
Full-Text   |   PDF [5050 KB, uploaded 25 January 2016]   |  


Anisotropic etching of silicon in potassium hydroxide (KOH) is an important technology in micromachining. The residue deposition from KOH etching of Si is typically regarded as a disadvantage of this technology. In this report, we make use of this residue as a second masking layer to fabricate two-layer complex structures. Square patterns with size in the range of 15–150 μm and gap distance of 5 μm have been designed and tested. The residue masking layer appears when the substrate is over-etched in hydrofluoric acid (HF) solution over a threshold. The two-layer structures of micropyramids surrounded by wall-like structures are obtained according to the two different masking layers of SiO2 and residue. The residue masking layer is stable and can survive over KOH etching for long time to achieve deep Si etching. The process parameters of etchant concentration, temperature, etching time and pattern size have been investigated. With well-controlled two-layer structures, useful structures could be designed for applications in plasmonic and microfluidic devices in the future. View Full-Text
Keywords: wet etching; potassium hydroxide; Si; pattern wet etching; potassium hydroxide; Si; pattern

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Lu, H.; Zhang, H.; Jin, M.; He, T.; Zhou, G.; Shui, L. Two-Layer Microstructures Fabricated by One-Step Anisotropic Wet Etching of Si in KOH Solution. Micromachines 2016, 7, 19.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Micromachines EISSN 2072-666X Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top