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- 实验方案
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A Novel Hybrid Removal Technology for High-Aspect-Ratio SU-8 Micromolds in ECF (Electro-Conjugate Fluid) Micropumps Fabrication by UV-LIGA
摘要： Previously, we have developed ECF micropumps with triangular prism and slit electrode pairs (TPSEs) fabricated by the UV-LIGA. However, the previous KMPR molds have a limit to attain higher-aspect-ratio TPSEs. As a promising substitute, the ultrathick SU-8 molds are preferable for the TPSEs due to higher-aspect-ratio ability, but their difficult removal remains an annoying problem. To solve this problem, we first propose a novel hybrid removal method combining CO2 laser engraving with O2/CF4 plasma to achieve the fast, non-swelling, and complete removal of ultrathick SU-8 micromolds for higher-aspect-ratio TPSEs. The CO2 laser engraving is utilized as the main process to remove most SU-8, while the O2/CF4 plasma is adopted as the post-treatment to remove the remaining SU-8. To gather the proper fabrication conditions, we quantitatively analyze the effects of laser power, laser scan speed, and laser-pass numbers on the SU-8 ablation thickness. We successfully fabricated TPSEs of 590 μm and 970 μm in height by selectively removing SU-8 micromolds of 620 and 1100 μm in thickness. This achievement confirmed that our hybrid removal technology could remove the crosslinked SU-8 effectively and efficiently. We further experimentally proved the fascinating potential of our hybrid removal in improving the output performance of ECF micropumps. This promising hybrid removal opens the door to the easier fabrication of ultrathick metallic microstructures by UV-LIGA.
关键词： high aspect ratio,ECF micropump,CO2 laser engraving,SU-8 removal,triangular prism & slit electrode pair
更新于2025-09-23 15:22:29
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The effect of size and aspect ratio on the trapped field properties of single grain, Y–Ba–Cu–O bulk superconductors
摘要： Bulk, single grain (RE)Ba2Cu3O7?δ [(RE)BCO, where RE is a rare earth element or yttrium] high temperature superconductors exhibit significant potential for use in a variety of engineering applications due to their ability to trap large magnetic fields, which can be up to ten times greater than those generated by conventional, iron-based magnets. Limitations on the maximum size to which single grains can be grown, however, are a major obstacle to the further development of these materials. Indeed, multiple samples are often required to achieve the required superconducting properties in particular applications. The geometry of bulk (RE)BCO single grain samples plays an important role in determining the superconducting properties of a given technical arrangement. In order to gain a better understanding of the full application potential of bulk single grain superconductors, three relatively long, cylindrical YBCO single grains of different diameters were fabricated and their trapped field and total trapped flux measured at 77 K as a function of sample height. The effects of size and aspect ratio of YBCO single grains on these key applied properties have been investigated experimentally and the results compared qualitatively with the predictions of an established theoretical model. Conclusions based on the trapped field measurements on a variety of single grain samples are presented in this study and the possibilities of using assemblies of smaller samples for engineering devices, in particular, are discussed.
关键词： distribution of the trapped field,aspect ratio,assemblies,bulk superconductors,applications
更新于2025-09-23 15:22:29
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Dependence of the Optimization of the Front Grid Design in Passivated Emitter and Rear Contact c-Si Solar Cells on the Finger Width and the Aspect Ratio
摘要： In this research, modeling was performed to optimize the grid of the front surface of a solar cell with the passivated emitter and rear contact (PERC) structure by considering the recombination characteristics. The front surface recombination velocity can be reduced in two main ways. The first method is to reduce the emitter Auger recombination by lowering the surface doping concentration during emitter formation, and the second method is to reduce the recombination that occurs at the surface when the electrode and the silicon are in contact, which is called metal-induced recombination and is represented by J0.metal. Because J0.metal increases in proportion to the area of the front electrode, minimizing the finger width and number by optimizing the electrode design is important. Therefore, the front electrode grid should be designed considering the emitter characteristics, J0.metal, according to the number of fingers and the resistance. In this research, the front grid of the solar cell was optimized via modeling using equations to calculate the number of fingers and the resistance. According to the finger width, the number of busbars, the sheet resistance, the aspect ratio, and the number of fingers corresponding to the maximum efficiency were identified. As a result, this modeling enabled us to optimize the front grid to the desired conditions, and we found that an increase in the number of busbars plays an important role in improving the efficiency of solar cells. In addition, the efficiency change with increasing number of busbars can be seen to be affected by the width of the finger and the resolution of the printed finger rather than the aspect ratio.
关键词： Aspect ratio,Finger width,Resistance,Front grid optimization,Crystalline silicon solar cells
更新于2025-09-23 15:21:01
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High-Resolution, High-Aspect-Ratio Printed and Plated Metal Conductors Utilizing Roll-to-Roll Microscale UV Imprinting with Prototype Imprinting Stamps
摘要： Micron-scale, high-aspect-ratio features were imprinted by a roll-to-roll process into a UV-curable polymer and used to create high-current-carrying conductive networks on plastic substrates. A stamp fabrication method was developed to create low-cost, rapidly produced roll-to-roll imprinting stamps, which can mold features from 3 μm to 1 mm wide. Isolated raised features 50 μm high were molded from a 25-μm-thick layer of UV-curable resin by displacing resin into raised features in the stamp. Substrates with imprinted capillary channels were used to form electrical conductors by printing a silver ink into reservoirs connected to the channels and allowing capillary flow to coat the channel. Copper electroless plating then filled the channels. The conductors demonstrate high resolution, high aspect ratio (～5:1 height:width), low resistance per length, and easy integration into networks. This roll-to-roll imprinting process provides a foundation for high-throughput manufacturing of high-resolution printed electronics.
关键词： high-aspect-ratio,conductive networks,roll-to-roll imprinting,UV-curable polymer,printed electronics
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Fabrication of SU-8 Microtowers for a 100-Turn Toroid Inductor
摘要： This paper presents a fabrication of extremely thick SU-8 photoresist process in a height range of 1000 μm to 2000 μm high-aspect-ratio microstructures. To differentiate conventional high-aspect-ratio tall structures less than 1000 μm, a new term, microtower, was adopted for the microstructure with a height of 1000 μm or taller. In fabrication process, to avoid a long softbaking process from the thick photoresist and provide uniform film thickness, an SU-8 dry film was adopted. Ultra-violet (UV) light exposure with an acrylic filter was investigated in terms of transparency of the applicable wavelength spectrum. An array of the 1000-μm tall microtower array was fabricated without the acrylic filter resulting in wavy sidewalls. Whereas an array of 2000-μm tall microtower was fabricated with the acrylic filter resulting straight sidewalls. An array of 1500-μm-long inclined V-pillars was also successfully fabricated by adopting the UV exposure with the acrylic filter, and the fabricated microstructures have potential use as a microfilter in microfluidics. A state-of-art 100-turn toroid inductor was successfully fabricated and electrically characterized resulting an average inductance of 950 nH in the frequency range of 0.1 to 10 MHz. A low-frequency resistance of 5.4 Ω at 0.1 MHz and a quality factor of 22 at 60 MHz were measured.
关键词： Micro tower,High aspect ratio,3-D Toroid inductor
更新于2025-09-19 17:15:36
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Etch Characteristics of Si and TiO<sub>2</sub> Nanostructures Using Pulse Biased Inductively Coupled Plasmas
摘要： The etch characteristics of Si and TiO2 nanostructures for optical devices were investigated using pulse biased inductively coupled plasmas (ICP) with SF6/C4F8/Ar and BCl3/Ar, respectively, and the results were compared with those etched using continuous wave (CW) biased ICP. By using pulse biasing compared to CW biasing in the etching in the line/pillar nanostructures of various aspect ratios, the reduction of aspect ratio dependent etching (ARDE), therefore, uniform etch depths for nanostructures with different pattern widths, and the improvement of the etch profiles without notching were obtained not only for silicon nanostructures but also for TiO2 nanostructures. It is investigated that the improvement of etch profiles and less ARDE effect by using pulse biasing are related to the decreased surface charging by neutralization of the surface and the improved radical adsorption (or etch byproduct removal) on the etched surfaces during the pulse-off period for the pulse biasing compared to CW biasing.
关键词： TiO2 nanostructure,Aspect ratio dependent etch (ARDE),Pulsed plasma etching,Etch profile,Si nanostructure
更新于2025-09-19 17:13:59
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3D Microlithography Using an Integrated System of 5-mm UV-LEDs with a Tilt-Rotational Sample Holder
摘要： This paper demonstrates a 3D microlithography system where an array of 5 mm Ultra Violet-Light Emitting Diode (UV-LED) acts as a light source. The unit of the light source is a UV-LED, which comes with a length of about 8.9 mm and a diameter of 5 mm. The whole light source comprises 20 × 20 matrix of such 5 mm UV-LEDs giving a total number of 400 LEDs which makes it a very favorable source with a large area for having a batch production of the desired microstructures. This light source is able to give a level of precision in microfabrication which cannot be obtained using commercial 3D printers. The whole light source performs continuous rotational movement once it is turned on. This can also move up and down in a vertical direction. This multidirectional light source also comprises a multidirectional sample holder. The light source teaming up with the multidirectional sample holder highly facilitates the process of fabrication of a huge range of 3D structures. This article also describes the different levels of characterization of the system and demonstrates several fabricated 3D microstructures including high aspect ratio vertical micro towers, twisted turbine structures, triangles, inclined pillar ‘V’ structures, and hollow horn structures as well.
关键词： Ultra Violet (UV) lithography,high aspect ratio,SU8 microstructure,3D microstructure,tilt rotational sample holder
更新于2025-09-19 17:13:59
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Micro‐/Nanopillars for Micro‐ and Nanotechnologies Using Inductively Coupled Plasmas
摘要： Herein, the plasma etching mask transfer of the resistance of e-beam resists, both negative and positive, as well as nanoparticle masks and hard masks are investigated. Various microscale and nanoscale features are exposed under plasma etching chemistries and are examined through both Bosch and pseudo-Bosch processes using an inductive-coupled plasma-deep reactive ion etching (ICP-DRIE) system. The selection of masks transfer proposed in this work provides better flexibility and cost-effective processing. The etch profile depending on plasma etching process and feature size is studied and highlighted. In particular, nanopillars are etched to a length of 10 μm and a diameter of 280 nm with a good aspect ratio (>30) yielding a selectivity of better than 100:1 and a satisfactory vertical profile.
关键词： plasma etching,micropillars,high aspect ratio,inductive-coupled plasma-deep reactive ion etching,nanopillars,selectivity
更新于2025-09-19 17:13:59
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Enhanced metal assisted etching method for high aspect ratio microstructures: Applications in silicon micropillar array solar cells
摘要： A solar cell device, fabricated on high density array cylindrical pillars, enables photogenerated carrier collection in the radial direction, thus shortening the path length of the carriers reaching the junction. It also provides advantages over conventional planar junction solar cells, such as reduced surface re?ectance and enhanced light trapping. In this study, highly ordered Si micropillars were fabricated by photolithography and metal assisted etching (MAE) methods. It is shown that the use of ethanol as a solvent during the etching process and increasing HF concentration in the MAE solution both improve the quality of the surfaces of the pillars. Micropillars with smooth sidewalls and a high aspect ratio were obtained in this way. Solar cells with a radial junction were then fabricated on these micropillars. Standard doping, SiO2/SiNx passivation, and metallisation steps were carried out for the fabrication of solar cells with di?erent micropillar lengths. A signi?cant decrease in re?ectance values was observed as the micropillar length increased, as expected. Solar cell short circuit current density (Jsc) and e?ciency (η) of the solar cells tended to increase with micropillar length up to 11.5 μm and then decrease due to increased surface recombination. The maximum e?ciency achieved in this study is 17.26%.
关键词： Solar cell,Ethanol,Micropillar,Metal assisted etching,High aspect ratio,Radial junction
更新于2025-09-16 10:30:52
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Laser Dissimilar Joining of Al7075T6 with Glass-Fiber-Reinforced Polyamide Composite
摘要： Dissimilar joining between metal and composite sheets is usually carried out by mechanical or adhesive joining. Laser dissimilar joining between metal and composite sheets could be an alternative to these methods, as it is a cost-effective and versatile joining technique. Previously, textured metallic and composite parts have been held together and heated with a laser beam while pressure is applied to allow the melted polymer to flow into the cavities of the metal part. The main issue of this process relates to reaching the same joint strength repetitively with appropriate process parameters. In this work, both initial texturing and laser joining parameters are studied for Al 7075-T6 and glass-fiber-reinforced PA6 composite. A groove-based geometry was studied in terms of depth-to-width aspect ratio to find an optimal surface using a nanosecond fiber laser for texturing. Laser joining parameters were also studied with different combinations of surface temperature, heating strategy, pressure, and laser feed rate. The results are relatively good for grooves with aspect ratios from 0.94 to 4.15, with the widths of the grooves being the most critical factor. In terms of joining parameters, surface reference temperature was found to be the most influential parameter. Underheating does not allow correct material flow in textured cavities, while overheating also causes high dispersion in the resulting shear strength. When optimal parameters are applied using correct textures, shear strength values over 26 kN are reached, with a contact area of 35 × 45 mm2.
关键词： metal polymer joint,groove aspect ratio,laser structuring,laser direct joining,shear strength
更新于2025-09-16 10:30:52