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2023 | OriginalPaper | Chapter

Effect of IPA on Micromachining Characteristics of Silicon in KOH-Based Solution

Authors : Avvaru Venkata Narasimha Rao, Prem Pal

Published in: Microactuators, Microsensors and Micromechanisms

Publisher: Springer International Publishing

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Abstract

Microstructures for microelectromechanical system (MEMS) applications are widely fabricated using silicon wet bulk micromachining technique. In this method, potassium hydroxide (KOH) is one of the most used anisotropic etchants. It provides high etch rate when it is modified by the addition of hydroxylamine (NH₂OH). Moreover, it shows high undercutting which is a desirable property for the fabrication of overhanging microstructures. In this paper, the effect of isopropyl alcohol (IPA) in NH₂OH-added KOH on the etching characteristics of Si{100} and Si{110}) is systematically studied. The results are compared with the etching characteristics of IPA-added pure KOH. The undercutting rate reduces drastically when IPA is added to NH₂OH + KOH which protects the convex corners of the structures during etching process. At the same time, the etch rate of {110} plane is suppressed considerable which is exploited to expose {110} plane at the mask edges aligned along <100> direction on {100} surface that makes 45° angle with {100} surface and act as a micromirror.

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previous chapter Etching Characteristics of Si{110} in NaOH Based Solution

next chapter Deep Grooves in Borofloat Glass by Wet Bulk Micromachining

Pal, P., Sato, K.: Silicon Wet Bulk Micromachining for MEMS. Pan Stanford Publishing, Singapore (2017)CrossRef

Koo, K.I., Chung, H., Yu, Y., Seo, J., Park, J., Lim, J.M., Paik, S.J., Park, S., Choi, H.M., Jeong, M.J., Kim, G.S.: Fabrication of pyramid shaped three-dimensional 8 × 8 electrodes for artificial retina. Sens. Actuators A Phys. 130, 609–615 (2006)

Narasimha Rao, A.V., Swarnalatha, V., Pandey, A.K., Singh, S.S., Pal, P.: Determination of precise crystallographic directions on Si{111} wafers using self-aligning pre-etched pattern. Micro Nano Syst. Lett. 6(1), 4 (2018)

Menon, P.K., Narasimha Rao, A.V., Murthy, A.L., Pandey, A.K., Pal, P.: High speed etching of silicon in KOH+NH₂OH solution at lower temperatures for the fabrication of through holes in silicon wafer. Micro Nano Lett., 1–6 (2020)

Yang, H., et al.: A novel method to fabricate single crystal nano beams with (111)-oriented Si micromachining. Microsyst. Technol. 14(8), 1185–1191 (2008)CrossRef

Pal, P., Sato, K.: Various shapes of silicon freestanding microfluidic channels and microstructures in one step lithography. J. Micromech. Microeng. 19(5), 055003 (2009)CrossRef

Rola, K.P., Zubel, I.: Impact of alcohol additives concentration on etch rate and surface morphology of (100) and (110) Si substrates etched in KOH solutions. Microsyst. Technol. 19(4), 635–643 (2013)

Seidel, H., Csepregi, L., Heuberger, A., Baumgärtel, H.: Anisotropic etching of crystalline silicon in alkaline solutions I. Orientation dependence and behavior of passivation layers. J. Electrochem. Soc. 137(11), 3612–3626 (1990)

Pal, P., Swarnalatha, V., Narasimha Rao, A.V., Pandey, A.K., Tanaka, H., Sato, K.: High speed silicon wet anisotropic etching for applications in bulk micromachining: a review. Micro Nano Syst. Lett. 9(1), 1–59 (2021)

10.

Pal, P., Sato, K., Gosalvez, M.A., Kimura, Y., Ishibashi, K., Niwano, M., Hida, H., Tang, B., Itoh, S.: Surfactant adsorption on single crystal silicon surfaces in TMAH solution: orientation-dependent adsorption detected by in-situ infra-red spectroscopy. J.Microelectromech. Syst. 18, 1345–1356 (2009)

11.

Xu, Y.W., Michael, A., Kwok, C.Y.: Formation of ultra-smooth 45° micromirror on (100) silicon with low concentration TMAH and surfactant: techniques for enlarging the truly 45° portion. Sens. Actuators A Phys. 166(1), 164–171 (2011)

12.

Zubel, I., Kramkowska, M.: The effect of alcohol additives on etching characteristics in KOH solutions. Sens. Actuators A Phys. 101(3), 255–261 (2002)CrossRef

13.

Zubel, I., Rola, K., Kramkowska, M.: The effect of isopropyl alcohol concentration on the etching process of Si-substrates in KOH solutions. Sens. Actuators A Phys. 171, 436–445 (2011)CrossRef

14.

Pal, P., Sato, K., Gosalvez, M.A., Shikida, M.: Study of rounded concave and sharp edge convex corners undercutting in CMOS compatible anisotropic etchants. J. Micromech. Microeng. 17(11), 2299–2307 (2007)

15.

Narasimha Rao, A.V., Swarnalatha, V., Pal, P.: Effect of surfactant and alcohol additives on etching characteristics in aqueous potassium hydroxide solutions. ECS Trans. 77(11), 1761–1769 (2017)

16.

Narasimha Rao, A.V., Swarnalatha, V., Ashok, A., Singh, S.S., Pal, P.: Effect of NH₂OH on etching characteristics of Si{100} in KOH solution. ECS J. Solid State Sci. Technol. 6(9), P609–P614 (2017)

17.

Narasimha Rao, A.V., Pal, P., Pandey, A.K., Swarnalatha, V., Menon, P, K., Tanaka, H., Sato, K.: Aging effects of KOH + NH₂OH solution on the etching characteristics of silicon. ECS J. Solid State Sci. Technol. 8(11), P685–P692 (2019)

18.

Narasimha Rao, A.V., Swarnalatha, V., Pal, P.: Etching characteristics of Si {110} in 20 wt% KOH with addition of hydroxylamine for the fabrication of bulk micromachined MEMS. Micro Nano Syst. Lett. 5(1), 1–9 (2017)

19.

Swarnalatha, V., Vismaya, K.T., Narasimha Rao, A.V., Pal, P., Pandey, A.K., Tanaka, H., Sato, K.: Etching mechanism behind the high speed etching of silicon in NH₂OH-added alkaline solutions. IEEJ Trans. Sens. Micromach. 140(1), 24–30 (2020)

20.

Zubel, I.: Anisotropic etching of Si. J. Micromech. Microeng. 29(9), 93002 (2019)CrossRef

21.

Gupta, A., Pal, P., Sharma, C.S.: Surface texturing of Silicon {100} in an extremely low concentration TMAH for minimized reflectivity. ECS J. Solid State Sci. Tech. 8(10), 622–628 (2019)

22.

Rai-Choudhury, P.: MEMS and MOEMS Technology and Applications. SPIE Press (2000)

23.

Pal, P., Sato, K.: A comprehensive review on convex and concave corners in silicon bulk micromachining based on anisotropic wet chemical etching. Micro Nano Syst. Lett. 3(1), 1–42 (2015). https://doi.org/10.1186/s40486-015-0012-4CrossRef

24.

Pal, P., Sato, K., Chandra, S.: Fabrication techniques of convex corners in (100)-silicon wafer using bulk micromachining: a review. J. Micromech. Microeng. 17(10), R111–R133 (2007)CrossRef

25.

Pal, P., Sato, K., Shikida, M., Gosalvez, M.A.: Study of corner compensating structures and fabrication of various shapes of MEMS structures in pure and surfactant added TMAH. Sens. Actuators A 154(2), 192–203 (2009)

Title: Effect of IPA on Micromachining Characteristics of Silicon in KOH-Based Solution
Authors: Avvaru Venkata Narasimha Rao
Prem Pal
Publisher: Springer International Publishing
Book: Microactuators, Microsensors and Micromechanisms
Print ISBN: 978-3-031-20352-7

Electronic ISBN: 978-3-031-20353-4

Copyright Year: 2023
DOI: https://doi.org/10.1007/978-3-031-20353-4_23