Rapid Plasma Etching for Fabricating Fused Silica Microchannels

Morikawa, Kyojiro; Matsushita, Karin; Tsukahara, Takehiko

doi:10.2116/analsci.33.1453

Cited by 19 publications

(15 citation statements)

References 26 publications

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“…Ar‐induced surface sputtering fosters the removal of nonvolatile products, which have a vapor pressure below the process pressure at typical surface temperatures and can trigger so‐called micromasking effects at the surface, as shown, for instance, in the study by Weigel et al [ 10,11 ] Furthermore, the energetic ion bombardment decreases the thickness of the polymer on the surface for an improved physical impact. [ 20,21 ] For glasses that form exclusively volatile products such as ULE glass, etching is promoted by CHF 3 addition that yields intrinsically an improved etching behavior.…”

Section: Resultsmentioning

confidence: 99%

Highly Anisotropic Fluorine‐Based Plasma Etching of Ultralow Expansion Glass

et al. 2021

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Deep etching of glass and glass ceramics is far more challenging than silicon etching. For thermally insensitive microelectromechanical and microoptical systems, zero‐expansion materials such as Zerodur or ultralow expansion (ULE) glass are intriguing. In contrast to Zerodur that exhibits a complex glass network composition, ULE glass consists of only two components, namely, TiO2 and SiO2. This fact is highly beneficial for plasma etching. Herein, a deep fluorine‐based etching process for ULE 7972 glass is shown for the first time that yields an etch rate of up to 425 nm min−1 while still achieving vertical sidewall angles of 87°. The process offers a selectivity of almost 20 with respect to a nickel hard mask and is overall comparable with fused silica. The chemical surface composition is additionally investigated to elucidate the etching process and the impact of the tool configuration in comparison with previously published etching results achieved in Zerodur. Therefore, deep and narrow trenches can be etched in ULE glass with high anisotropy, which supports a prospective implementation of ULE glass microstructures, for instance, in metrology and miniaturized precision applications.

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Section: Resultsmentioning

confidence: 99%

Highly Anisotropic Fluorine‐Based Plasma Etching of Ultralow Expansion Glass

et al. 2021

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“…Micro/nanofluidic devices were fabricated by the top-down fabrication of micro- and nanochannels on glass substrates, based on reported methods [ 8 , 30 , 31 ]. Nanochannels with sizes of 100 to 1000 nm were fabricated by electron beam lithography and dry etching.…”

Section: Methodsmentioning

confidence: 99%

A Simple Low-Temperature Glass Bonding Process with Surface Activation by Oxygen Plasma for Micro/Nanofluidic Devices

et al. 2020

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The bonding of glass substrates is necessary when constructing micro/nanofluidic devices for sealing micro- and nanochannels. Recently, a low-temperature glass bonding method utilizing surface activation with plasma was developed to realize micro/nanofluidic devices for various applications, but it still has issues for general use. Here, we propose a simple process of low-temperature glass bonding utilizing typical facilities available in clean rooms and applied it to the fabrication of micro/nanofluidic devices made of different glasses. In the process, the substrate surface was activated with oxygen plasma, and the glass substrates were placed in contact in a class ISO 5 clean room. The pre-bonded substrates were heated for annealing. We found an optimal concentration of oxygen plasma and achieved a bonding energy of 0.33–0.48 J/m2 in fused-silica/fused-silica glass bonding. The process was applied to the bonding of fused-silica glass and borosilicate glass, which is generally used in optical microscopy, and revealed higher bonding energy than fused-silica/fused-silica glass bonding. An annealing temperature lower than 200 °C was necessary to avoid crack generation by thermal stress due to the different thermal properties of the glasses. A fabricated micro/nanofluidic device exhibited a pressure resistance higher than 600 kPa. This work will contribute to the advancement of micro/nanofluidics.

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“…Microchip 1 having a microchannel (depth, 30 ± 1.5 m; width, 1000 ± 50 m; outer circumference, 2060 ± 70 m; cross-sectional area, 3.0 ± 0.2 × 10 4 m 2 ) was fabricated via photolithography and dry etching, as described in previous studies. 21,22 A quartz glass substrate (size, 30 × 70 mm; thickness, 0.7 mm; VIOSIL-SX, Shin-Etsu Quartz Co., Ltd., Tokyo, Japan) was used. The glass substrate was sputtered with Cr to a thickness of 50 µm.…”

Section: Microchip Fabricationmentioning

confidence: 99%

Design of Microchannel Suitable for Packing with Anion Exchange Resins: Uranium Separation from Seawater Containing a Large Amount of Cesium

et al. 2021

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We present a resin-packed microchannel that can reduce the radiation exposure risk and secondary radioactive wastes during uranium (U) separation by downscaling the separation using a microchip. Two types of microchips were designed to densely pack the microchannels with resins. The microchannels had almost the same cross-sectional area but different outer circumferences. A satisfactory separation performance could be obtained by arranging more than ca. 10 resins along the depth and width of the microchannels. The resin-packed microchannel is an effective separation technique for determining U concentration via inductively coupled plasma mass spectrometry owing to its ability to avoid the contamination of the equipment by cesium and reduce the matrix effect. The size of the separation site was scaled down to <1/5000 compared to commonly used counterparts. The radiation exposure risk and secondary radioactive wastes can be reduced by 10-and 800-fold, respectively, using the resin-packed microchannel.

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Rapid Plasma Etching for Fabricating Fused Silica Microchannels

Cited by 19 publications

References 26 publications

Highly Anisotropic Fluorine‐Based Plasma Etching of Ultralow Expansion Glass

Highly Anisotropic Fluorine‐Based Plasma Etching of Ultralow Expansion Glass

A Simple Low-Temperature Glass Bonding Process with Surface Activation by Oxygen Plasma for Micro/Nanofluidic Devices

Design of Microchannel Suitable for Packing with Anion Exchange Resins: Uranium Separation from Seawater Containing a Large Amount of Cesium

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