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- 摘要
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- 实验方案
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Effect of Dielectric Charging on Capacitance Change of an SOI Based CMUT
摘要： Effect of dielectric charging on the performance of SOI based Capacitive Micromachined Ultrasonic Transducers (CMUT) has been investigated. Measurements on an SOI based CMUT show that that the capacitance change as a function of DC bias is considerably higher than analytically calculated values. Investigation shows that this deviation in capacitance from analytically calculated values is due to the combined effects of different dielectric charging phenomena due to a strong electric field, trap charges in the SOI oxide layer, the charge motion associated with the leakage current through the buried oxide layer, and the air in the CMUT cavity. Additionally, this charging effect degrades the transduction efficiency as the induced polarization reduced the effective bias across the CMUT. It is concluded that the buried oxide (BOX) layers in SOI wafers are not suitable for use as dielectric spacers in electrostatic MEMS devices.
关键词： SOI,dielectric charging,Capacitance,microfabrication,MEMS,CMUT,leakage current
更新于2025-11-14 17:28:48
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Sacrificial Layer Technique for Releasing Metallized Multilayer SU-8 Devices
摘要： The low fabrication cost of SU-8-based devices has opened the fields of point-of-care devices (POC), μTAS and Lab-on-Chip technologies, which call for cheap and disposable devices. Often this translates to free-standing, suspended devices and a reusable carrier wafer. This necessitates a sacrificial layer to release the devices from the substrates. Both inorganic (metals and oxides) and organic materials (polymers) have been used as sacrificial materials, but they fall short for fabrication and releasing multilayer SU-8 devices. We propose photoresist AZ 15nXT (MicroChemicals GmbH, Ulm, Germany) to be used as a sacrificial layer. AZ 15nXT is stable during SU-8 processing, making it suitable for fabricating free-standing multilayer devices. We show two methods for cross-linking AZ 15nXT for stable sacrificial layers and three routes for sacrificial release of the multilayer SU-8 devices. We demonstrate the capability of our release processes by fabrication of a three-layer free-standing microfluidic electrospray ionization (ESI) chip and a free-standing multilayer device with electrodes in a microchannel.
关键词： microfabrication,microfluidics,free standing,microchips,SU-8,sacrificial release,multi layered chips,AZ 15nXT
更新于2025-09-23 15:23:52
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Technological Assessment of MEMS Alkali Vapor Cells for Atomic References
摘要： This paper is a review that surveys work on the fabrication of miniature alkali vapor cells for miniature and chip-scale atomic clocks. Technology on microelectromechanical systems (MEMS) cells from the literature is described in detail. Special attention is paid to alkali atom introduction methods and sealing of the MEMS structure. Characteristics of each technology are collated and compared. The article’s rhetoric is guided by the proposed classification of MEMS cell fabrication methods and contains a historical outline of MEMS cell technology development.
关键词： MEMS cells,atomic references,microfabrication,frequency standards
更新于2025-09-23 15:22:29
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Maskless lithography based on digital micromirror device (DMD) and double sided microlens and spatial filter array
摘要： A new type of maskless lithography system based on digital mirror device (DMD) is proposed, constructed, and experimentally demonstrated. It includes a pin-hole array sandwiched by two microlens arrays on each side, known as double-sided microlens/spatial-filter array (D-MSFA), and aligned with a DMD. Ultraviolet (UV) light reflected by DMD is first collected by the first microlens array, filtered through the pin-hole array, and then re-focused by the second microlens array into a UV spot array. Along with an obliquely scanning method, this D-MSFA/DMD-based maskless lithography system can perform not only 2D but also 3D UV patterning. Experimental testing successfully generates complicated patterns with a minimum line-width of 3.36 μm. Direct 3D patterning and 3D microfabrication are also experimentally demonstrated on a photoresist layer. Excellent profile accuracy and surface structure qualities are observed with great potentials for future 2D and 3D microfabrication in a maskless manner.
关键词： Microlens array,Maskless lithography,Digital mirror device (DMD),3D microfabrication
更新于2025-09-23 15:22:29
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Techniques and Considerations in the Microfabrication of Parylene C Microelectromechanical Systems
摘要： Parylene C is a promising material for constructing flexible, biocompatible and corrosion-resistant microelectromechanical systems (MEMS) devices. Historically, Parylene C has been employed as an encapsulation material for medical implants, such as stents and pacemakers, due to its strong barrier properties and biocompatibility. In the past few decades, the adaptation of planar microfabrication processes to thin film Parylene C has encouraged its use as an insulator, structural and substrate material for MEMS and other microelectronic devices. However, Parylene C presents unique challenges during microfabrication and during use with liquids, especially for flexible, thin film electronic devices. In particular, the flexibility and low thermal budget of Parylene C require modification of the fabrication techniques inherited from silicon MEMS, and poor adhesion at Parylene-Parylene and Parylene-metal interfaces causes device failure under prolonged use in wet environments. Here, we discuss in detail the promises and challenges inherent to Parylene C and present our experience in developing thin-film Parylene MEMS devices.
关键词： MEMS,Parylene,microfabrication
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Silicon Cold Field Emission Electron Sources for Electron Microscopy Inspection Systems
摘要： Next generation electron beam inspection tools will require a high brightness electron source. We have designed, microfabricated and tested arrays of metal coated silicon cold field emitters that have high current density and high reduced brightness, offering a promising alternative to thermal field emitters. One of the main challenges that must be addressed with cold field emitters is achieving stable emission current. Using current pulsing, we have been able to improve the stability of field emission currents and have demonstrated beam currents with less than 1% noise.
关键词： electron source,microfabrication,cold field emission,electron microscopy,inspection systems,cathode,silicon
更新于2025-09-23 15:21:21
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Mechanism and Experimental Study of Femtosecond-Laser Super-Resolution Processing Based on Beam Shaping Technology
摘要： The three-dimensional microsolid can be fabricated by scanning point-by-point inside the polymer material according to the predetermined trajectory in femtosecond-laser two-photon direct writing mode. In the process of machining, the shape and intensity distribution of focus spot are changed by some processing parameters, which a?ect the processing accuracy and surface quality. Based on Fresnel di?raction theory and the intensity distribution function of focal spot, the focal spot shape is simulated and the main factors a?ecting the light intensity distribution are analyzed theoretically and simulated numerically. We propose a shaping method to improve the asymmetric shape of the facula by adding a prefocusing lens. According to the mechanism of femtosecond-laser super-resolution processing, we propose a beam shaping method using four-ring complex transmittance phase plate to achieve super-resolution processing. The phase plate was optimized on the global optimization algorithm and genetic algorithm. The validation experiment was carried out by scanning the photochromic material ?lm with pulsed laser and reading the ?uorescence signal of the photochromic point with single photon confocal. The experimental results show that the facula distribution is approximately symmetrical, and the size of facula is decreased obviously. The compression ratio is basically consistent with the theoretical calculation results. Therefore, super-resolution processing can be achieved by adding pre-focusing lens and phase plate to shaping the laser beam. The results of theoretical and experimental studies provide su?cient basis for improving the machining accuracy and surface quality of microdevices.
关键词： beam shaping,femtosecond laser,super resolution,microfabrication
更新于2025-09-23 15:21:01
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A Novel Topology for Process Variation-Tolerant Piezoelectric Micromachined Ultrasonic Transducers
摘要： This paper presents a novel architecture for piezoelectric micromachined ultrasonic transducers (PMUT) allowing for a drastic reduction in the impact of process variations on the accuracy of the resonant frequency. At the core of this new topology is a toroidal anchoring technique. Measurement results show that inter- and intra-die resonant frequency standard variations can be reduced from 101 kHz to 23 kHz and from 20 kHz to 5.9 kHz, respectively, by using the method proposed in this paper, showcasing devices fabricated using the PiezoMUMPs commercial fabrication technology. From the 16 chips that have been fabricated, each holding 12 PMUT devices of two different topologies, resonant frequency results are presented and analyzed to assess the effectiveness of the proposed approach. In addition, as a proof of concept, the fabricated PMUT are demonstrated to perform distance ranging measurements.
关键词： frequency,ranging measurements,variability,process variation,MEMS,PMUT,Piezoelectric ultrasonic transducers,microfabrication
更新于2025-09-23 15:21:01
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[ASME ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - Quebec City, Quebec, Canada (Sunday 26 August 2018)] Volume 4: 23rd Design for Manufacturing and the Life Cycle Conference; 12th International Conference on Micro- and Nanosystems - A Novel Method for Rapid Microfabrication
摘要： We introduce a novel microfabrication method using direct writing of photoresist with an ultrasonic microplotter equipped. First, the photoresist is driven into the pipette through capillary forces. The pipette is then used to directly write microfeatures on a polydimethylsiloxane (PDMS) substrate. The photoresist is cured on a hot-plate and used as a mold for replication. A second layer of PDMS is cast onto the mold. Once cured on a hot-plate, it is peeled off from the mold to obtain the desired microfeatures. We demonstrate that this method can be used for ultra-rapid and cost-effective fabrication of microchannels (39.65 μm wide) without need for clean room facilities.
关键词： Microchannels,PDMS,Rapid microfabrication
更新于2025-09-23 15:21:01
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Micromachined Filters at 450 GHz With 1% Fractional Bandwidth and Unloaded Q over 700
摘要： This paper presents two silicon-micromachined narrowband 4th order waveguide filter concepts with center frequency of 450 GHz, which are the first narrowband submillimeter-wave filters implemented in any technology with a fractional bandwidth as low as 1%. Both filters designs are highly compact and have axial port arrangements, so that they can be mounted directly between two standard waveguide flanges without needing any split-block interposers. The first filter concept contains two TM110 dual-mode cavities of circular shape with coupling slots and perturbations arranged in two vertically stacked layers, while the second filter concept is composed of four TE101 series resonators arranged in a folded, two-level topology without cross-couplings. Prototype devices are fabricated in a low-surface roughness deep-silicon etching on silicon-on-insulator wafers. The measured passband insertion loss of two prototype devices of the dual-mode circular-cavity filters is 2.3 dB, and 2.6 dB for three prototypes of the folded filter design. The corresponding extracted unloaded quality factors of the resonators are 786±7 and 703±13 respectively, which are the best so far reported for submillimeter-wave filters in any technology. The presented filters are extremely compact in terms of size; their footprints have areas of only 0.53 and 0.55 mm2, respectively, and the thickness between the waveguide flanges is 0.9 mm.
关键词： micromachining technology,microfabrication,waveguide filters,all-pole filters,dual-mode filters
更新于2025-09-23 15:21:01