X-ray lithography: Some history, current status and future prospects

Maldonado, Juan R.; Peckerar, Martin C.

doi:10.1016/j.mee.2016.03.052

Cited by 54 publications

(31 citation statements)

References 20 publications

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“…These methods, however, are very time consuming and require advanced cleanroom facilities, making them cost prohibitive for general drug delivery. Thus, there is a need to explore new fabrication approaches that are low cost and can be carried out without expensive cleanroom facilities 12,13 . Here, we propose a simple three-step cleanroom-free method to make microneedles.…”

Section: Introductionmentioning

confidence: 99%

Low-cost and cleanroom-free fabrication of microneedles

et al. 2018

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We present a facile, low-cost and cleanroom-free technique for the fabrication of microneedles using molds created by laser ablation. Microneedle mold with high aspect ratios is achieved on acrylic sheet by engraving a specific pattern of crossover lines (COL) using CO 2 laser cutter. Ablating COL pattern on the acrylic sheet creates a sharp conical shape in the center of the design. We have shown that a variety of microneedle shapes with different heights and tip angles can be easily achieved by changing the number and the length of the COL. Polydimethylsiloxane (PDMS) microneedles were fabricated by casting the PDMS on the mold. The resulted PDMS microneedles are oxygen plasma treated and then silanized. Another PDMS layer is casted on PDMS microneedles and detached after curing. The silanization prevents those two layers of PDMS from bonding to each other and makes them easily detachable. After detachment of the PDMS mold of microneedles, the mold is used to fabricate degradable polyvinyl alcohol microneedle patch suitable for transdermal drug delivery. The release kinetics of the needles are also shown and discussed in order to prove the applicability of the needles.

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Section: Introductionmentioning

confidence: 99%

Low-cost and cleanroom-free fabrication of microneedles

et al. 2018

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“…XRL, however, is mainly targeting soft matter photoresists that are chemically altered by radiation chemistry and subsequently etched. Furthermore, standard XRL uses relatively large spot sizes and nanostructuring is typically achieved by lithography masks [26][27][28][29][30][31][32]. Very few studies have employed the focused beam of a scanning transmission X-ray microscope (STXM) for maskless direct-write patterning of polymer films [33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Additive Nano-Lithography with Focused Soft X-rays: Basics, Challenges, and Opportunities

Späth

2019

Micromachines

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Focused soft X-ray beam induced deposition (FXBID) is a novel technique for direct-write nanofabrication of metallic nanostructures from metal organic precursor gases. It combines the established concepts of focused electron beam induced processing (FEBIP) and X-ray lithography (XRL). The present setup is based on a scanning transmission X-ray microscope (STXM) equipped with a gas flow cell to provide metal organic precursor molecules towards the intended deposition zone. Fundamentals of X-ray microscopy instrumentation and X-ray radiation chemistry relevant for FXBID development are presented in a comprehensive form. Recently published proof-of-concept studies on initial experiments on FXBID nanolithography are reviewed for an overview on current progress and proposed advances of nanofabrication performance. Potential applications and advantages of FXBID are discussed with respect to competing electron/ion based techniques. polymer resulting in 3D patterning by radiation chemistry [33,34]. The approach is limited to materials with significantly different absorption cross-sections at the chosen incident photon energies, as in transmission geometry, all layers are exposed to the beam at different degrees of focusing. However, such experiments open a completely novel perspective for complex direct-write nanofabrication. It should be mentioned that during the late 1980s and early 1990s several groups attempted to exploit broad-band synchrotron light [38][39][40][41] as well as the monochromatic X-ray beam of a photon-induced scanning Auger microscope [42,43] for additive manufacturing of metal deposits from metal organic precursors. However, due to limited instrumental capabilities, only spatially extended thin films with an optimum of some 10 µm resolution could be produced [43].FXBID exploits the photon energy-selectivity of synchrotron-based XRL and extends it by the idea of depositing metal nanostructures from suitable precursor gases [21,22]. The use of a STXM setup for these experiments offers several advantages. STXM is a raster-scanning technique which avoids the necessity of shadow masks. According to comparable results from polymer lithography the theoretical minimum feature size of the deposited metal structures is mainly determined by the spot size of the incident beam [36,37]. Recent developments in X-ray optics have pushed this parameter below 10 nm [44,45]. Finally, STXM can be employed for an in-situ analysis of the metallic deposits directly after fabrication by means of resonant imaging and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to evaluate confinement, growth rates, oxidation state and chemical purity [21,22,46,47]. X-ray magnetic circular dichroism (XMCD) can be used to characterize magnetic deposits with respect to their magnetization and coercivity [48].This review presents some basic principles of X-ray optics and X-ray microscopy as well as X-ray beam dosimetry that are relevant for FXBID experiments. In accordance, limitations, challenges and opportunities of additiv...

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“…Indeed, masks usually consist of a pattern of a strongly X-ray-absorbing material (typically gold) supported by thin membranes made of silicon nitride, titanium, graphite, or polymers. For transparency reasons, such membranes are only few micrometers thick, but should often extend over big areas making them very delicate 4 . Other relevant problems are represented by the availability of suitable light sources, mask-wafer positioning, and diffraction effects 5 .…”

Section: Introductionmentioning

confidence: 99%

Maskless X-Ray Writing of Electrical Devices on a Superconducting Oxide with Nanometer Resolution and Online Process Monitoring

Mino

Bonino

Agostino

et al. 2017

Sci Rep

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X-ray nanofabrication has so far been usually limited to mask methods involving photoresist impression and subsequent etching. Herein we show that an innovative maskless X-ray nanopatterning approach allows writing electrical devices with nanometer feature size. In particular we fabricated a Josephson device on a Bi2Sr2CaCu2O8+δ (Bi-2212) superconducting oxide micro-crystal by drawing two single lines of only 50 nm in width using a 17.4 keV synchrotron nano-beam. A precise control of the fabrication process was achieved by monitoring in situ the variations of the device electrical resistance during X-ray irradiation, thus finely tuning the irradiation time to drive the material into a non-superconducting state only in the irradiated regions, without significantly perturbing the crystal structure. Time-dependent finite element model simulations show that a possible microscopic origin of this effect can be related to the instantaneous temperature increase induced by the intense synchrotron picosecond X-ray pulses. These results prove that a conceptually new patterning method for oxide electrical devices, based on the local change of electrical properties, is actually possible with potential advantages in terms of heat dissipation, chemical contamination, miniaturization and high aspect ratio of the devices.

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X-ray lithography: Some history, current status and future prospects

Cited by 54 publications

References 20 publications

Low-cost and cleanroom-free fabrication of microneedles

Low-cost and cleanroom-free fabrication of microneedles

Additive Nano-Lithography with Focused Soft X-rays: Basics, Challenges, and Opportunities

Maskless X-Ray Writing of Electrical Devices on a Superconducting Oxide with Nanometer Resolution and Online Process Monitoring

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