Fabrication

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

Fabrication of silicon oxide microneedles from macroporous silicon

Abstract: This paper presents a novel technique for silicon dioxide (SiO2) microneedle fabrication. Microneedles are hollow microcapillaries with tip diameters in the range of micrometers. They can be used in the fabrication of microsyringes. These structures can be of high interest in medical and biological applications, such as DNA injection, antibody manipulation and drug delivery, and cell manipulation. Fabrication process is based on electrochemical etching of n-type silicon in hydrofluoric acid (HF) solutions. Basic process flow and etching conditions that ensure a stable pore growth are described. These conditions also determine the geometry of the resulting microneedle structure. Microneedle arrays of different dimensions can be fabricated in a single run on the same wafer. In this work, microneedle arrays with pore diameters ranging from 2 to 5 µm, pore lengths from 30 to 140 µm and wall thicknesses in the range of 70–110 nm are reported.

Fabrication and characterization of reactive nanoscale multilayer systems for low-temperature bonding in microsystem technology

Abstract: Reactive bonding is a still new low-temperature joining process that is based on reactive nanoscale multilayer systems. The heat required for the bonding process is generated by a self-propagating exothermic reaction within the multilayer system while the adhesive interconnect is supported by solder films. For microsystem applications, the approach is particularly useful if temperature-sensitive components and materials with high differences in coefficient of thermal expansion have to be joined. In this paper, this is successfully demonstrated for bonding a quartz strain gauge onto a stainless steel membrane and an IR-emitter onto a covar socket by using commercially available nickel/aluminum NanoFoils©. The quality of the bond interface of both demonstrators was investigated by scanning electron microscopy and the strength was determined by a tensile test. On the other hand, integrated microsystem applications beyond die attachment require patterned bond structures, e.g. to form bond frames. Thus, alternative materials were additionally considered that can be directly deposited on silicon substrates by magnetron sputtering, such as aluminum/titanium as well as titanium/amorphous silicon (Ti/a-Si) bilayer systems. The properties of these basic multilayer systems and their reaction products were characterized by differential scanning calorimetry and high-resolution electron microscopy. It is shown that specifically the Ti/a-Si system has substantial potential for direct microsystem technology integration provided the remaining open technological issues can be addressed during future research. In general, the results obtained in this study demonstrate the high potential of the reactive bonding process as a new advantageous assembly technology for the fabrication of future microsystems.

Ideally Ordered Anodic Porous Alumina Mask Prepared by Imprinting of Vacuum-Evaporated Al on Si : Instrumentation, Measurement, and Fabrication Technology

Abstract: Application of imprinting of vacuum-evaporated Al on a Si substrate using an SiC mold with an ordered array of hexagonally arranged convexes and subsequent anodization yielded an ideally ordered porous alumina mask on the substrate. The obtained alumina mask has sufficient adhesion to a Si substrate, and was used as a mask for vacuum evaporation of metal and ion milling of the Si substrate.

Design, fabrication and characterization of stacked layers planar broadband metamaterial absorber at microwave frequency

Abstract: The design, simulation, fabrication, and measurement of an ultra-wide spectral band metamaterial absorber were investigated in this paper. The unit cell consisting of three loop copper layers were printed on FR-4 epoxy dielectric substrate, and the top layer was Teflon. By stacking a number of one-layer structures on top of each other, a multi-layered structure was generated with a thickness of 3.7 mm. Results of the recursive method and the simulations showed a high absorption for wide angle of incidence up to 60° at TM and TE modes. The absorption at normal incidence was strong in the frequency range of 5.64–21.16 GHz numerically. The proposed structure was fabricated. The experimental results showed a good correspondence with the simulated results. Importantly, the design can be extended to other frequencies, such as terahertz, infrared, and optical frequencies.

Free standing single-crystal silicon microstructures

Abstract: Micromachined structures of single-crystal silicon have been fabricated with a view to developing them for a number of potential uses. The structures which are fabricated in (111) orientation silicon are undoped thus permitting the incorporation of active circuit elements in the structures themselves. Moreover no high temperatures, applied voltages or long etch times are used in the fabrication sequence, thereby simplifying the task of integration with circuit processes. The potential uses of these structures include photodiodes with high speed and efficiency, accelerometers, or structures for stress or thermal isolation.