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Open AccessArticle

Infinite Selectivity of Wet SiO2 Etching in Respect to Al

1
Central European Institute of Technology, Brno University of Technology, 612 00 Brno, Czech Republic
2
Department of Microelectronics, Faculty of Electrical Engineering and Communication, Brno University of Technology, 616 00 Brno, Czech Republic
3
Department of Microsystem Engineering, School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China
*
Author to whom correspondence should be addressed.
Micromachines 2020, 11(4), 365; https://doi.org/10.3390/mi11040365
Received: 29 February 2020 / Revised: 30 March 2020 / Accepted: 31 March 2020 / Published: 31 March 2020
(This article belongs to the Section D:Materials and Processing)
We propose and demonstrate an unconventional method suitable for releasing microelectromechanical systems devices containing an Al layer by wet etching using SiO2 as a sacrificial layer. We used 48% HF solution in combination with 20% oleum to keep the HF solution water-free and thus to prevent attack of the Al layer, achieving an outstanding etch rate of thermally grown SiO2 of ≈1 µm·min−1. We also verified that this etching solution only minimally affected the Al layer, as the chip immersion for ≈9 min increased the Al layer sheet resistance by only ≈7.6%. The proposed etching method was performed in an ordinary fume hood in a polytetrafluorethylene beaker at elevated temperature of ≈70 °C using water bath on a hotplate. It allowed removal of the SiO2 sacrificial layer in the presence of Al without the necessity of handling highly toxic HF gas. View Full-Text
Keywords: SiO2 etching; microelectromechanical systems (MEMS); sacrificial layer; selectivity SiO2 etching; microelectromechanical systems (MEMS); sacrificial layer; selectivity
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MDPI and ACS Style

Gablech, I.; Brodský, J.; Pekárek, J.; Neužil, P. Infinite Selectivity of Wet SiO2 Etching in Respect to Al. Micromachines 2020, 11, 365. https://doi.org/10.3390/mi11040365

AMA Style

Gablech I, Brodský J, Pekárek J, Neužil P. Infinite Selectivity of Wet SiO2 Etching in Respect to Al. Micromachines. 2020; 11(4):365. https://doi.org/10.3390/mi11040365

Chicago/Turabian Style

Gablech, Imrich; Brodský, Jan; Pekárek, Jan; Neužil, Pavel. 2020. "Infinite Selectivity of Wet SiO2 Etching in Respect to Al" Micromachines 11, no. 4: 365. https://doi.org/10.3390/mi11040365

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