Fabrication

About: Fabrication is a research topic. Over the lifetime, 20475 publications have been published within this topic receiving 235676 citations.

Fabrication and characterization of folded SU-8 suspensions for MEMS applications

Abstract: A novel wafer-level fabrication technique for polymeric springs combined with a silicon proof mass is presented for applications in MEMS force sensors or scanning micromirrors. Furthermore, passive test structures for the determination of mechanical parameters of the polymer are integrated on the wafer during device fabrication. The test structures allow for chip scale process monitoring in respect to the material parameters. The large difference of material stiffness and thickness between the springs and the proof mass concentrates the entire mechanical deformation into the springs. Furthermore, the polymeric springs can be used as electrically isolated suspension for electrostatically levitated devices. Devices have been fabricated and characterized by means of frequency response analysis. Thereby, a polymeric suspension with a spring constant of 8.7 N/m is presented, while the suspended structure itself features a spring constant of 140 kN/m. Material properties of the spring material (SU-8 2025) were measured to be 2.45 ± 0.6 GPa, 27.2 ± 2.2 MPa and 13.8 ± 3.2 MPa/m, for Young's modulus, the residual stress and the residual stress gradient, respectively.

Nanostructure and Microstructure Fabrication: From Desired Properties to Suitable Processes

Abstract: When designing a new nanostructure or microstructure, one can follow a processing-based manufacturing pathway, in which the structure properties are defined based on the processing capabilities of the fabrication method at hand. Alternatively, a performance-based pathway can be followed, where the envisioned performance is first defined, and then suitable fabrication methods are sought. To support the latter pathway, fabrication methods are here reviewed based on the geometric and material complexity, resolution, total size, geometric and material diversity, and throughput they can achieve, independently from processing capabilities. Ten groups of fabrication methods are identified and compared in terms of these seven moderators. The highest resolution is obtained with electron beam lithography, with feature sizes below 5 nm. The highest geometric complexity is attained with vat photopolymerization. For high throughput, parallel methods, such as photolithography (≈101 m2 h−1), are needed. This review offers a decision-making tool for identifying which method to use for fabricating a structure with predefined properties.

Fabrication of porous anodic aluminium oxide layers on paper for humidity sensors

Abstract: The fabrication process of anodic aluminium oxide (AAO) on a paper-based substrate is challenging because the use of a highly economical, conformable and ecological substrate. This process is based on a simple, cost-effective, self-ordering anodization of aluminium, which yields a vertically aligned and a highly ordered nanoporous structure. The manufacturing process on a flexible substrate with the use of phosphoric acid is described, and a capacitive sensor produced on this layer is investigated versus the humidity concentration and the frequency. The AAO morphology and the structure obtained were analysed, and the electrical properties of the sensing layer were investigated, using a 4192A LF network analyser in a climatic chamber. The surface conduction mechanism and the effect of humidity on the dielectric properties of a porous anodic aluminium oxide are discussed.

Precision fabrication techniques and analysis on high-Q evanescent-mode resonators and filters of different geometries

Abstract: High-Q evanescent-mode resonators and filters are realized by both silicon micromachining and layer-by-layer polymer processing. Capacitively loaded cavities can be reduced to a size much smaller than a wavelength, but still have a much higher unloaded Q than lumped elements. The loaded resonators are utilized for reduced-size filters with a low insertion loss enabled by the relatively high-Q factor. The small fabrication tolerances of silicon micromachining and polymer stereolithography processing enable the realization of highly loaded evanescent-mode resonators and filters. A 14-GHz resonator micromachined in silicon has a volume of 5 mm /spl times/ 5 mm /spl times/ 0.45 mm, representing a resonant frequency reduction of 66.8% compared to an empty cavity of the same dimensions. The polymer-based fabrication is used to create resonators of different three-dimensional geometries with Q's up to 1940 and frequency reductions up to 49.9%. An insertion loss of 0.83 dB is measured in a 1.69% bandwidth filter created by polymer processing with a frequency reduction of 47% compared to an unloaded cavity. The frequency sensitivity to fabrication tolerances of these structures is also analyzed.

Large Scale Graphene/Hexagonal Boron Nitride Heterostructure for Tunable Plasmonics

Abstract: Vertical integration of hexagonal boron nitride (h-BN) and graphene for the fabrication of vertical field-effect transistors or tunneling diodes has stimulated intense interest recently due to the enhanced performance offered by combining an ultrathin dielectric with a semi-metallic system. Wafer scale fabrication and processing of these heterostructures is needed to make large scale integrated circuitry. In this work, by using remote discharged, radio-frequency plasma chemical vapor deposition, wafer scale, high quality few layer h-BN films are successfully grown. By using few layer h-BN films as top gate dielectric material, the plasmon energy of graphene can be tuned by electrostatic doping. An array of graphene/h-BN vertically stacked micrometer-sized disks is fabricated by lithography and transfer techniques, and infrared spectroscopy is used to observe the modes of tunable graphene plasmonic absorption as a function of the repeating (G/h-BN)n units in the vertical stack. Interestingly, the plasmonic resonances can be tuned to higher frequencies with increasing layer thickness of the disks, showing that such vertical stacking provides a viable strategy to provide wide window tuning of the plasmons beyond the limitation of the monolayer.