Topic
Lithography
About: Lithography is a research topic. Over the lifetime, 23507 publications have been published within this topic receiving 348321 citations.
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TL;DR: In this article, the conditions of elasticity, roughness, and energy of adhesion to establish conformal contact between an elastomer and the target surface were analyzed, and the authors addressed questions of replication accuracy and evaluated local elastic deformation induced by normal forces.
Abstract: Patterning in soft lithography techniques such as microcontact printing or light-coupling mask lithography is mediated by surface topographical patterns of elastomeric stamps: intimate contact with the substrate is achieved locally at the protruding areas, whereas a gap remains between the substrate and recessed zones. This principle challenges the properties of the stamp, especially when printing high-resolution or extreme aspect-ratio patterns with high accuracy. On the one hand, the stamp must be soft enough to enable conformal contact with the substrate, which means that it must adapt elastically without leaving voids created by the natural roughness of the substrate. On the other hand, a precise definition of micropatterns requires a rigid material. In this article, we analyze the conditions of elasticity, roughness, and energy of adhesion to establish conformal contact between an elastomer and the target surface. Furthermore, we address questions of replication accuracy and evaluate local elastic deformation induced by normal forces using model calculations for simple pattern geometries. Pressure applied during contact leads to a sagging or collapse of the unsupported areas. We discuss implications on both material and pattern design that allow spontaneous propagation of conformal contact while inhibiting the spreading of collapse.
326 citations
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TL;DR: In this paper, the SU-8 50 negative photoresist (PR) was used for fabricating ultra-thick microfluidic devices using standard UV lithography.
Abstract: In this paper we describe a new process for fabricating ultra-thick microfluidic devices utilizing SU-8 50 negative photoresist (PR) by standard UV lithography. Instead of using a conventional spin coater, a simple 'constant-volume-injection' method is used to create a thick SU-8 PR film up to 1.5 mm with a single coating. The SU-8 PR is self-planarized during the modified soft-baking process and forms a highly-uniform surface without any edge bead effect, which commonly occurs while using a spin coater. Photomasks can be in close contact with the PR and a better lithographic image can be generated. Experimental data show that the average thickness is 494.32 ± 17.13 μm for a 500 μm thick film (n = 7) and the uniformity is less than 3.1% over a 10 × 10 cm2 area. In this study, the temperatures for the soft-baking process and post-exposure baking are 120 °C and 60 °C, respectively. These proved to be capable of reducing the processing time and of obtaining a better pattern definition of the SU-8 structures. We also report on an innovative photomask design for fabricating ultra-deep trenches, which prevents the structures from cracking and distorting during developing and hard-baking processes. In this paper, two microfluidic structures have been demonstrated using the developed novel methods, including a micronozzle for thruster applications and a microfluidic device with micropost arrays for bioanalytical applications.
315 citations
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TL;DR: In this paper, the authors report sub-nanometer linewidth uniformity in silicon nanophotonics devices fabricated using high-volume CMOS fabrication tools, using wavelength-selective devices such as ring resonators, Mach-Zehnder interferometers, and arrayed waveguide gratings to assess the device nonuniformity within and between chips.
Abstract: We report subnanometer linewidth uniformity in silicon nanophotonics devices fabricated using high-volume CMOS fabrication tools. We use wavelength-selective devices such as ring resonators, Mach-Zehnder interferometers, and arrayed waveguide gratings to assess the device nonuniformity within and between chips. The devices were fabricated using 193 or 248 nm optical lithography and dry etching in silicon-on-insulator wafer technology. Using 193 nm optical lithography, we have achieved a linewidth uniformity of 2 nm (after lithography) and 2.6 nm (after dry etch) over 200 mm wafer. Furthermore, with the developed fabrication process, using wavelength-selective devices, we have demonstrated a linewidth control better than 0.6 nm within chip and better than 2 nm chip-to-chip. The necessity for high-resolution optical lithography is demonstrated by comparing device nonuniformity between the 248 and 193 nm optical lithography processes.
311 citations
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TL;DR: A new low-cost, high-throughput approach to maskless nanolithography that uses an array of plasmonic lenses that 'flies' above the surface to be patterned, concentrating short-wavelength surface plasmons into sub-100 nm spots.
Abstract: The commercialization of nanoscale devices requires the development of high-throughput nanofabrication technologies that allow frequent design changes1,2. Maskless nanolithography3,4,5,6,7,8,9,10,11,12,13, including electron-beam and scanning-probe lithography, offers the desired flexibility but is limited by low throughput. Here, we report a new low-cost, high-throughput approach to maskless nanolithography that uses an array of plasmonic lenses that ‘flies’ above the surface to be patterned, concentrating short-wavelength surface plasmons into sub-100 nm spots. However, these nanoscale spots are only formed in the near field, which makes it very difficult to scan the array above the surface at high speed. To overcome this problem we have designed a self-spacing air bearing that can fly the array just 20 nm above a disk that is spinning at speeds of between 4 and 12 m s−1, and have experimentally demonstrated patterning with a linewidth of 80 nm. This low-cost nanofabrication scheme has the potential to achieve throughputs that are two to five orders of magnitude higher than other maskless techniques. Maskless nanolithography is a flexible nanofabrication technique but it suffers from low throughput. By developing a new approach that involves 'flying' an array of plasmonic lenses just 20 nm above a rotating surface, it is possible to increase throughput by several orders of magnitude.
308 citations
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TL;DR: Three-dimensional multiphoton lithography at 520 nm has been used to fabricate polymeric woodpile photonic crystal structures that show stop bands in the near-infrared spectral region.
Abstract: Nanoscale features as small as 65 +/- 5 nm have been formed reproducibly by using 520 nm femtosecond pulsed excitation of a 4,4'-bis(di-n-butylamino)biphenyl chromophore to initiate crosslinking in a triacrylate blend. Dosimetry studies of the photoinduced polymerization were performed on chromophores with sizable two-photon absorption cross-sections at 520 and 730 nm. These studies show that sub-diffraction limited line widths are obtained in both cases with the lines written at 520 nm being smaller. Three-dimensional multiphoton lithography at 520 nm has been used to fabricate polymeric woodpile photonic crystal structures that show stop bands in the near-infrared spectral region.
306 citations