The precise 3D microstructures with a high aspect ratio are needed in many advance applications. This paper describes recent advantages and prospects of precise 3D microfabrication with a high aspect ratio. Especially LIGA process using synchrotron radiation is applied to pattern regist layers with typical thickness from several μm to 2000μm. Here next technical targets of LIGA process are described. And a variety of ultra Precise 3D microstructures process brought LIGA process allows a new diffraction grating for obtaining high-resolution phase data. We developed the fabrication technique composed MEMS process and LIGA process. The line width and the aspect ratio of this grating are 4μm and above 7, respectively. We evaluated the diffraction grating in SPring 8.

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Two-photon microstereolithography can provide complicated three-dimensional microstructures with nearly 100 nm resolution in three-dimensions. This technique is one of promising methods to produce disposable functional biochips. However it needs a long time to fabricate thick microstructures owing to its high depth resolution. To solve this problem, we tried to control the thickness of microstructures by changing the numerical aperture of an objective lens and input laser power. As a result, we succeeded in fabricating microgears whose thickness is from 0.59μm to 1.57μm. We also demonstrated that the optical torque of the thick microgear was higher than that of the thin microgear. Additionally the microgear was stably rotated by the optimization of the clearance between the gear and the shaft. Finally we fabricated engaged cogwheels by making each microgear at different height to avoid sticking of the two microgears.

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Arrays of micro overhanging structures were fabricated with very high uniformity by negative-tone photoresist of SU-8 and novel lithography technique, inclined rotary stage and backside exposure. Conventional chrome mask with an array of apertures was used as a substrate, and photoresist was directly spun on the mask. Rotational symmetric structures of SU-8 were obtained by irradiating through the apertures from the backside of the mask, inclining and rotating the stage. It is also possible to fabricate more elaborate and multilevel structures by using another photomask which partially blocks the rays at desired phase of rotation. In addition, light-guiding device with uniform draft angle was prototyped with this technique by using positive-tone photoresist of PMER P-CA1000PM and molding technique.

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The rapid microminiaturization of LSI chips has encouraged the need for similarly microminiaturizing the probes of probe cards, the parts used to inspect IC chips. In response to this need, a method of producing 3-dimensional microprobes is devised by etching a substrate in advance and then performing X-ray lithography. By examining and optimizing each part of the process, we produced a 3-dimensional microprobe with the desired shape. The microprobe was 18 μm wide and 50 μm thick, with a tip 185 μm high, consisting of both the spring part and the tip. The mechanical and electrical properties of the microprobe were estimated by measuring the contact force and contact resistance. The measurement showed satisfactory results: the contact force allowed a displacement magnitude as large as 80 μm, accompanied by a satisfactory contact force of 0.39 gf. In addition, the contact resistance exhibited low and stable values when contact was formed on an object made of Au exhibiting a contact force of 0.1 gf or more, demonstrating the high potential of the prototyped microprobes.

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This paper proposes a method for fabricating size-varied structures from nanometer scale to millimeter scale on the same wafer precisely. The advancement in nanometer scale lithography and DRIE have enabled us to develop a lot of applications of high aspect ratio nano structures. However, DRIE conditions optimized for nanometer scale openings are often incompatible with large size openings due to the aspect ratio dependence of optimum conditions. Applying DRIE conditions optimized for small openings to large openings results in lots of silicon pillars in trenches. To solve the problem, this paper proposes a two-step etching method: the etching of nano-structures plus contours of large area patterns followed by the etching of the rest with optimum conditions respectively. The contours etching in the first step enabled us precise alignment of nano-patterns to large patterns. Its capability has been shown by successful fabrication of optical switches which are consisted of large etched areas and fine comb-drive actuators on a 4-inch 25 μm SOI wafer.

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An exposure method for realizing fine patterning on three-dimensional samples is described. Three-dimensional sample requires the different viewpoint from that of the proximity patterning. Concave areas can not be geometrically approached to the mask. The fine patterning becomes difficult due to the broadening of the exposure light. In this study, the phase shift mask is combined with the well-collimated mercury lamp. 5 μm-width line pattern is stably obtained on the 200 μm-deep cavity bottom.

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The stability diagram of the Fabry-Perot resonator composed of two spherical mirrors is calculated by the Kirchhoff diffraction integral equation. We have derived the proper equation from the integral and diagonalized it. It has also been calculated the dependence of the stability diagram on the Fresnel number.

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A guiding mechanism for a magnetic levitated conveyor using a high temperature superconductor is reported in this paper. We focused on millimeter and centimeter components size of the superconductor and the levitating magnet. The magnetic guide is formed on the superconductor, which was made by Melt Powder Melt growth (MPMG) method, by partially magnetizing it with the magnets of the stick and ring shapes. Then we put the levitating magnet on the superconductor. The magnet levitated 3mm above the superconductor stably. It was guided successfully along the pre-magnetized path. However, we found a problem that the levitating magnet tends to stay at one or a few points along the magnetic guiding path. We report experimental results and the consideration of this phenomenon.

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We propose an OPtical LEAd Frame (OPLEAF) that serves as the interface between an optical fiber array and high density optical IC. OPLEAF allows significant size reduction of optical IC. Recent advances in the miniaturization of optical ICs have made it possible to realize adjacent optical device spacing of 10μm-order. The OPLEAF converts the pitch from 250μm to 30μm and provides a miniaturized interface between fibers and the optical IC. OPLEAF is unification with tape fiber (fiber array) and connected to the optical IC directly; thus alignment is necessary only at one end. The maximum loss due to the curvature was evaluated to be 1.5dB from optical experiment. The value agrees well with the 1.3dB obtained from Beam Propagation Method (BPM) simulation.

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This paper presents a 5-axis motion sensor that can detect 3-axis acceleration and 2-axis angular rate capacitively. This sensor is fabricated by SOI bulk-micromachining, and is sealed vacuum by anodic bonding and activation of the non-evaporated getters. By applying Z-axis reference vibration of a proof mass with an electrostatic force at resonant frequency, 5-axis motions can be detected capacitively at non-resonant detection mode. How the resonant frequency of driving direction and detection direction of this sensor changed by size of the weight, beam width, beam thickness and beam length, was clarified. Three samples were made by this design method, and acceleration characteristic and angular rate characteristic were measured, and the effectiveness was shown.

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Development of a rapid and precise an onboard speedometer for vehicles is a major concern for emerging Intelligent Transportation System's infrastructure. This paper presents a highly precise speed calibration system for vehicles based on Micro Wave Sensor (MWS) technology. The new system has two invisible antennas which are laid out in a horizontal and a vertical-shape, respectively. The system's architecture includes ultra-low power consumption microcontroller loaded with a software program which has intelligent capabilities such as self and auto- calibration features.

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