L. Dellmann

Applications of SOI-based optical MEMS

After microelectromechanical systems (MEMS) devices have been well established, components of higher complexity are now developed. Particularly, the combination with optical components has been very successful and have led to optical MEMS. The technology of choice for us is the silicon-on-insulator (SOI) technology, which has also been successfully used by other groups. The applications presented here give an overview over what is possible with this technology. In particular, we demonstrate four completely different devices: (a) a 2 /spl times/ 2 optical cross connector (OXC)with an insertion loss of about 0.4 dB at a switching time of 500 /spl mu/s and its extension to a 4 /spl times/ 4 OXC, (b) a variable optical attenuators (VOA), which has an attenuation range of more than 50 dB (c) a Fourier transform spectrometer (FTS) with a spectral resolution of 6 nm in the visible, and (d) an accelerometer with optical readout that achieves a linear dynamic range of 40 dB over /spl plusmn/6 g. Except for the FTS, all the applications utilized optical fibers, which are held and self-aligned within the MEMS component by U-grooves and small leaf springs. All devices show high reliability and a very low power consumption.

Advanced deep reactive ion etching: a versatile tool for microelectromechanical systems

Advanced deep reactive ion etching (ADRIE) is a new tool for the fabrication of bulk micromachined devices. Different sensors and actuators which use ADRIE alone or combined with other technologies such as surface micromachining of silicon are presented here. These examples demonstrate the potential and the design freedom of this tool, allowing a large number of different shapes to be patterned and new smart devices to be realized.

Fabrication process of high aspect ratio elastic and SU-8 structures for piezoelectric motor applications

We report on recent advances in micro fabrication technology using micromolding and high aspect ratio structuring of photopolymer. The direct application is the realization of components for millimeter-size, ultrasonic piezoelectric motors. A new fabrication process using a thick epoxy-based material (SU-8) and the electroplating of nickel is demonstrated. Photopolymer structures have also been realized and released using a positive tone resist as sacrificial layer. The main advantages over past fabrication methods are better design flexibility, simplicity of the fabrication process, the capability to combine metallic materials (Ni) with polymeric materials ( SU-8), and the use of positive tone resist as a sacrificial layer

High aspect ratio UV photolithography for electroplated structures

This paper describes single and two layer processes to realize thick resist moulds (40 and 80 µm) with a good reproducibility. The patterning of a thick AZ 4562 photoresist layer is performed with standard photolithography equipment. Different problems related to thick photoresist patterning (edge bead, resist cracking, ...) are discussed and solutions are proposed. Side walls are characterized after nickel electrodeposition and mould dissolution in acetone. Results, process limitations and applications are presented.

Fabrication process of high aspect ratio elastic structures for piezoelectric motor applications

Briefly reports on advances in the fabrication technology of components for millimeter size ultrasonic piezoelectric motors. A very large height to width aspect ratio with good lateral patterning resolution is required for the active component in acoustic mode conversion. A new fabrication process using a thick epoxy-based material (SU-8) and the electroplating of nickel is demonstrated. The main advantages over past fabrication methods are better flexibility in the design, simplicity of the fabrication process and the combination of metallic materials (Ni) with polymeric materials (SU-8). The mechanical properties of SU-8 have been measured using free cantilever beam structures.

4X4 matrix switch based on MEMS switches and integrated waveguides

We present the development of a 4×4 matrix of optical switches based on silicon microfabricated switches and integrated waveguides. The device consists of two chips connected together by flip-chip bonding. The first chip has 16 latched silicon switches with micro-mirrors, while the second one contains the integrated waveguides and ensures the electrical connection of the 16 switches. The incorporation of integrated waveguides, patterned using a SU-8 mask and deep reactive ion etching, in our switch devices allows both the size and the packaging complexity to be reduced, and a technology for higher order matrices to be developed.

Microsystems for diverse applications using recently developed microfabrication techniques

The continuous progress in micro- and nano-system technologies has allowed the successful development of many innovative products in process control, environmental monitoring, healthcare, automotive and aerospace as well as information processing systems. In this paper on overview will be given of current progress in micro- and nanofabrication process technologies, such as deep reactive ion etching, micro-electro discharge machining, thick photoresistant processing and plating. The availibility of these micro- and nanofabrication processes will be illustrated with examples of new generations of silicon-based sensors, actuators and Microsystems with a particular emphasis on real applications of these components and systems.

Patterned thick photoresist layers for protection of protruding structures during wet and dry etching processes

Thick photoresist (about 40 m) was patterned and used as a protective layer for protruding structures (sharp, high aspect ratio atomic force microscope tips) in wet (buffered hydrofluoric acid) and dry (reactive ion etching) etching. The process and results of its use are discussed, and some applications are proposed.

Micromachined piezoelectric elastic force motor (EFM)

This paper will focus on the fabrication and characterization of two types of piezoelectric motors based on the elastic force motor principle. The initial motivation for this work was the development of a motor for wristwatch applications, combining high torque (1 /spl mu/m) with low power consumption (10 /spl mu/W) and small dimensions. Previously reported motors were based on a hybrid assembly of a copper-beryllium rotor, obtained by laser cutting, and a stator consisting of a circular membrane, clamped along its border. The membrane was anisotropically etched in silicon and covered with either ZnO or PZT. We report on an improved and further miniaturized version with fully microfabricated rotors and a new stator design.

4x4 non-blocking matrix switch based on MOEMS

We present the design and characterization of a new 4 X 4 switch based on the previously developed 2 X 2 fiber switch. The switching principle uses plasma etched vertical mirrors that can be moved in and out of two pairs of optical fibers with the integrated electrostatic actuator. The 4 X 4 switch is built by connecting 16 individual 2 X 2 switches in a common package (100 X 50 X 35 mm). Instead of integrating the 16 switch elements on the same chip, we preferred assembling the switches by fusion splicing. The insertion loss is less than 1.8 dB for each state.