G.-A. Racine

Microfabricated Lamb wave device based on PZT sol-gel thin film for mechanical transport of solid particles and liquids

The fabrication using silicon micromachining and characterization of an acoustic Lamb wave actuator is presented. The intended use of the device is for mass transport and sensor applications. The device consists of dual interdigitated transducers patterned on a thin-film composite membrane of silicon nitride, platinum, and a sol-gel-derived piezoelectric ceramic (PZT) thin film. The acoustic properties of the device are presented along with preliminary applications to mechanical transport and liquid delivery systems. Improved acoustic signals and improved mass transport are achieved with PZT over present Lamb wave devices utilizing ZnO or AlN as the piezoelectric transducer.

Piezoelectric cantilever beams actuated by PZT sol-gel thin film

The mechanical response of piezoelectric cantilever beams actuated by sol-gel- derived lead zirconium titanate (PZT) thin film is reported. Small multilayered beams are used to analyse the converse piezoelectric effect and to measure the mechanical deflection of the beams with a standard interferometry method. Interferometric displacement measurements, electrical measurements and finite- element simulations are reported to determine the piezoelectric coefficient d(31) of the PZT thin film.

Microfabrication of 3D multidirectional inclined structures by UV lithography and electroplating

A new process for the fabrication of 3D multidirectional inclined structures is presented. Based on a modified W exposure of commercially available thick positive photoresist and electrodeposition, this process can be carried out using common clean room equipment. To realise inclined structures, inclined rotating exposures are performed through two shifted masks integrated in the photoresist layers. By adequate shifts between the apertures of both masks, this new technique allows three dimensional structures inclined in any direction and with different tilt angles to be fabricated on the same substrate. This paper deals with the different fabrication steps and the simulation required for the accurate determination of several of the parameters needed for the masks. These parameters, such as the dimensions of the apertures, the shift angles between them or the thickness of the separation layer between the two masks have to be determined for each different tilt angle of the structures. By this new process, 10/spl deg/ inclined structures with heights up to 120 /spl mu/m and with nearly parallel sidewalls have been fabricated. This technology opens a wide range of new applications. In particular, a first prototype of a new rotor for the Elastic Force Motor (EFM) has been fabricated by electroplating tilted legs on a previously electroplated wheel.

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.

Hybrid ultrasonic micromachined motors

A hybrid ultrasonic motor has been fabricated using silicon micromachining and metallic micromechanical components. The concept of elastic force motors (EFMs) is applied for the conversion of standing waves to mechanical energy. Millimeter-size prototypes (6*6*2 mm) show interesting characteristics. Free rotation speed up to 600 rpm and net torque of 50 nNm are observed. Typical applications are the motorization of electronic watches or the positioning systems in instrumentation.<<ETX>>

Fabrication and characterization of cantilevers with integrated sharp tips and piezoelectric elements for actuation and detection for parallel AFM applications

Abstract We have developed a new process to fabricate arrays of cantilevers with integrated tips for atomic force microscope (AFM) imaging and a piezoelectric layer for vertical actuation and detection. A good homogeneity of the tip shape is obtained thanks to a self-sharpening effect. The cantilevers have been characterized mechanically and electrically.

Ultrasonic flexural Lamb-wave actuators based on PZT thin film

The fabrication and characterization of a microfabricated acoustic Lamb-wave device driven by a piezoelectric PZT (modified lead zirconate titanate Pb(Zr-x,Ti1-x)O-3) sol-gel thin film for use in mass-transport, mass-filtering and fluid-delivery systems are presented. Ultrasonic flexural plate waves (FPWs) at frequencies of the order of megahertz are generated and detected in a thin acoustic composite membrane by using two interdigitated transducers (IDTs) patterned on a 0.75 mu m thick piezoelectric ceramic PZT film, which provides high acoustic power for physical translation of fluid and microparticles