Supercritical CO2 drying of poly(methyl methacrylate) photoresist for deep x-ray lithography: a brief note

Rahul Shukla; Lala Abhinandan; Shivdutt Sharma

doi:10.1117/1.JMM.16.3.034506

27 September 2017 Supercritical CO₂ drying of poly(methyl methacrylate) photoresist for deep x-ray lithography: a brief note

Rahul Shukla, Lala Abhinandan, Shivdutt Sharma

Author Affiliations +

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 16, Issue 3, 034506 (September 2017). https://doi.org/10.1117/1.JMM.16.3.034506

Abstract

Poly(methyl methacrylate) (PMMA) is an extensively used positive photoresist for deep x-ray lithography. The post-development release of the microstructures of PMMA becomes very critical for high aspect ratio fragile and freestanding microstructures. Release of high aspect ratio comb-drive microstructure of PMMA made by one-step x-ray lithography (OXL) is studied. The effect of low-surface tension Isopropyl alcohol (IPA) over water is investigated for release of the high aspect ratio microstructures using conventional and supercritical (SC) CO₂ drying. The results of conventional drying are also compared for the samples released or dried in both in-house developed and commercial SC CO₂ dryer. It is found that in all cases the microstructures of PMMA are permanently deformed and damaged while using SC CO₂ for drying. For free-standing high aspect ratio microstructures of PMMA made by OXL, it is advised to use low-surface tension IPA over DI water. However, this brings a limitation on the design of the microstructure.

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Rahul Shukla, Lala Abhinandan, and Shivdutt Sharma "Supercritical CO₂ drying of poly(methyl methacrylate) photoresist for deep x-ray lithography: a brief note," Journal of Micro/Nanolithography, MEMS, and MOEMS 16(3), 034506 (27 September 2017). https://doi.org/10.1117/1.JMM.16.3.034506

Received: 28 June 2017; Accepted: 6 September 2017; Published: 27 September 2017

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