Lowering internal impedance, i.e., stray capacitance and resistance, is essential to enhance the output power of microelectromechanical system (MEMS) vibrational energy harvesters particularly when the structure is made of a silicon-on-insulator (SOI) wafer which has a distributed stray capacitance across the buried oxide (BOX) layer. Instead of using silicon as a material for electrical interconnection, we used an out-of-plane aluminum bonding wire to complete the on-chip electrical interconnection between the contact pads on the chip frame and the suspended movable electrodes. Compared with the conventional design using silicon-based interconnections, the maximum deliverable power has been enhanced almost six-fold because of the reduced stray capacitance between the SOI layer and the substrate, as well as reduced internal electrical resistance. The mechanical stability of the bonded wire during the excitation vibration has also been experimentally confirmed. A typical power density of 763 µW/cm³ is obtained when excited by 0.5 G (1 G = 9.8 m/s²) sinusoidal vibrations at 157 Hz.

Metal deposition is one of the important fabrication process for the electrical wires as well as bonding pads in micrelectromechanical systems (MEMS). For the development of MEMS devices, especially in university, common facilities are sometimes used. The machine conditions in such the facility are uncontrollable, therefore the properties of deposited film are unstable. In this paper, problems of contact resistance as well as adhesion using the shared machine were reported. Finally, a method to improve the film quality using such the machine was proposed. This information is important for the MEMS device development using the hand-on facilities.

Three-dimensional force distribution based on magnetic resonance in microsamples can be obtained by Si nanomechanical cantilevers with a magnet. Highly sensitive magnetic sensors require operation under high-Q, high-vacuum conditions. To overcome the limitation of operation in vacuum conditions, a force sensor for magnetic resonance detection with a vacuum-sealed magnetic cantilevers was developed. A silicon-based cantilever with a magnet particle was enclosed in a vacuum chamber using anodic-bonding and direct metal (Sn-Al) bonding. The proposed vacuum sealed magnet-based cantilever has confirmed the high feasibility of magnetic resonance force detection within a non-hermetic environment. The fabrication process of mounting the magnets one by one is undesirable in terms of manufacturing cost. Compared to other deposition methods, the electroplating method of magnetic material can produce thicker magnetic films and lower production costs. On the other hand, force detection with sensors with high Q-factor has a long response time. In order to reduce the measurement time, we proposed a two-dimensional force transducer with Si thin wires assembled on a glass trench and a bridge resonator including a field-effect transistor.

Character Projection (CP) method and variable-shaped beam (VSB) are very unique and powerful drawing methods for high-throughput electron Beam (EB) lithography system. These methods have much interests to the industries due to the wafer scale exposure capability and time effective in the order of magnitude. However, the tradeoff of the exposure quality according to the EB exposure pattern approximation methods has not yet been comprehensively studied. Our study is essential for photonics because target patterns are curbed waveguide. We propose 100 nm octangular CP sleeving methods with several overlap parameters for the optical racetrack resonator test structure. Two approximation techniques were tried such as 100 nm octagonal CP and fine variable-shaped rectangles. Optical measurement clearly revealed quality differences between these methods, and this method is very useful for the curved structure and time effective technique.

This paper proposes a patterning method for color filters using a method to introduce fluids of uncured color inks into capillaries with rectangular cross sections. Flat surface of color filter patterns can be obtained owing to the flat ness of top and bottom surfaces of the PDMS mold replicated from SU-8 photoresist patterns. In addition, the plural color filter patterns can automatically be formed by filling inks with capillary force. Mixing ratio of additive and solvent (dye, heptane, PVA and PDMS) were varied in order to decrease capillary filling time in consideration of capillary theory for viscous fluid.

This paper reports a Lorentz force frequency modulated (FM) MEMS magnetometer using superposed clockwise (CW) and counter clockwise (CCW) modes on a degenerated quad mass resonator. Sensing currents synchronous to the oscillation generate Lorentz forces which modify the modal stiffnesses, eventually resonant frequencies. Sensing currents correspond to both modes have the same amplitudes but opposite directions, thus the frequencies of CW and CCW modes could be shifted in the opposite direction by the applied magnetic field. In this paper, the principle of magnetometer was introduced using theoretical model. The whole system including the MEMS resonator, CW/CCW mode separators, feedback controllers were modelled and numerically simulated. The degenerated CW and CCW modes could be successfully separated and independently controlled. The frequencies of these modes were modulated by the magnetic field as predicted by the theory. The estimated sensitivity was 4.91Hz/mT. The MEMS resonator for the proposed system was designed, fabricated and the basic functions of transducers in the device were evaluated. Both the electrostatic and electromagnetic transducers worked as designed. The resonant frequency was 8.1kHz and the Q factor was 26,000.

In this paper, we have fabricated surface acoustic wave (SAW) devices with six sets of interdigital transducers (IDTs) on half-inch wafers of quartz with deposited thin films of aluminum nitride (AlN). Firstly, AlN thin films have been deposited by reactive sputtering in Ar-N₂ gas mixture at 400°C with the high power impulse magnetron sputtering (HiPIMS) system which was developed for microfabrication process in the localized clean environment with half-inch wafer (Minimal Fab). After that, IDTs of Al thin films have been prepared on the AlN thin films. The X-ray diffraction (XRD) pattern of the AlN thin films shows that the AlN films have c-axis (002) orientation. Furthermore, the frequency responses have been measured with four paired IDTs of the SAW devices, which were selected from six sets of IDTs as an input electrode and an output electrode. These results show device properties responding to the design of the IDTs and also suggest the potential of the fabricated SAW devices as the 4-paralleled frequency filter and/or sensing system.