This paper proposes a concept of a concurrent configuration of radio-frequency (RF) micromachined and micro-electro-mechanical-system (MEMS) devices. The devices are fabricated on an originally developed dielectric-air-metal (DAM) structure that suits for fabrication of various devices all together. The DAM structure can propose membrane-supported hollow elements embedded in a silicon wafer by creating cavities in it. Even though the devices have different cavity depths, they are processed by just one planarization. In addition, since the structure is worked only from the front side of the wafer, no flipping process as well as no wafer bonding process is required, and the fact realizes low-cost concurrent integration. As applications of the DAM structures, a hollow grounded co-planar waveguide, lumped element circuitries, and an MEMS switch are demonstrated.

A historical overview of microoptomechatronics technologies is presented for positioning of microoptomechatronics, accompanied with a future view based on the current state of art nanotechnologies. How the technologies have been developed for realizing practical precision and information devices based on optics or photonics is also mentioned, citing a few examples.

The relation between resonant frequency of micromirror with vertical combdrives and applied voltage between the upper and lower comb teeth was analyzed. Resonant frequency of the micromirror was controlled by stiffness of the torsion hinge. Resonant frequency of the mirror was proportional to the applied voltage between the upper and lower comb teeth at the same tilt angle.

The lithography process on the deep trench pattern above the large cavity is proposed to fabricate the MEMS structure. Generally, bubbles generated on the trench patterns when it was baked after coating resist. The probability of the generation of bubbles was reduced by decreasing the backing rate. The fast scanning micromirror with 50.8 kHz resonant frequency was fabricated by controlling the backing rate.

Photovoltaic devices capable of generating more than 200 volts with an area of 1 cm2 have been developed for directly driving microactuators such as piezoelectric or electrostatic actuators. The micro-devices interconnect 285 micro cells (unit cell size: about 0.5 mm 2.0 mm) in series, and have an open circuit voltage (Voc) of 207 volts, a short circuit current (Isc) of 36.6 µA, a maximum output power (Pmax) of 4.65 mW and a fill factor (F.F.) of 0.615 under AM (Air Mass) 1.5 and 100 mW/cm2 illumination. This voltage is the highest in the world for the area of 1 cm2. The series connection is precisely processed by a focused laser beam, thereby significantly reducing the area needed for device connections. It has been confirmed that a piezoelectric polymer can be directly driven by the electrical output in evaluating the potential of the devices to be used as a microactuator's power source.

Micromechanisms and actuators which are 10-100 micrometers in size are studied by research groups in universities, national research institutes, and private industries in Japan. Some of them belong to a "Micromachine Technology" project lead by MITI (Ministry of International Trade and Industries). Microfabrication technologies based on both IC-compatible processes and mechanical machining are under development. Application-oriented devices in automobile, communication and information industries are also investigated. The research goal is to build a smart micro system through the integration of moving mechanisms, sensors and electronics on a chip; this is the fusion of mechanics and electronics in the microscopic world. This paper reviews recent activities in MEMS research in Japan.

The present paper describes a novel approach to interconnecting and assembling components of MEMS at room temperature. The main drawback of the conventional bonding methods is their rather high process temperatures. The new method, which is referred as the surface activated bonding (SAB), utilizes the phenomena of the adhesion between two atomically clean solid surfaces to enable the bonding at lower temperature or even at room temperature. In the bonding procedure, the surfaces to be bonded are merely brought into contact after sputter-cleaning by Ar fast atom in ultrahigh vacuum conditions. TEM observations of the bonded interfaces show that a direct bonding in atomic scale is achieved in the interface between the micro-components. Based on the concept of this new bonding technology, a micro-assembly system was developed. The micro-assembly system is operated by means of a virtual manipulation system in which 3D model of the micro-components are manipulated virtually in a computer graphics constructed in the world wide web (WWW) scheme. The micro-assembly system will provide a new design tool of three dimensional MEMS by combining the possibility of the flexible assembly and the intuitive operations.