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.
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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 StyleGablech, 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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