Eric Cattan

Lamb wave and plate mode in ZnO/silicon and AlN/silicon membrane: Application to sensors able to operate in contact with liquid

Abstract Lamb waves, especially the A 0 mode, can be used to build sensors able to operate in contact with liquid. Nevertheless, some difficulties remain for practical devices. First, we discuss the relevance of the electromechanical coefficient. We present the element of choice of the device characteristics and the piezoelectric material. We compare two kinds of devices, the first is a classical delay line device and the second a resonant device. The behavior of these devices has been controlled using optical visualization of vibration modes. Furthermore, the performance of the devices is experimentally tested and advantages of the resonant device are shown.

Piezoelectric properties of PZT films for microcantilever

The investigation of piezoelectric properties of materials in the thin layer form has become an important task because of the increased range of their applications as actuators and sensors. The sensor magnitude, is a direct function of the e31 piezoelectric constant. Pb(Zr,Ti)O3 thin films and the modified compositions have attracted great attention in recent years as promising for use in microelectromechanical systems. To determine this constant we use an unusual experimental method. A remanent piezoelectric constant of −4.7 C/m2 was obtained. The parameters as, coercive field, saturation field, curve of first polarization, and self polarization of the remanent piezoelectric hysteresis loop are presented for 1.6 μm thick PZT thin film. We will associate also dielectric results. To show the possible integration of the piezoelectric films in microelectromechanical systems, we have deposited PZT thin film on a 100 μm long, 20 μm wide, 1 μm thick silicon oxide beam to control the z actuation.

PMNT films for integrated capacitors

Abstract This article investigates the sputter deposition of thin films in the solid solution of lead magnesium niobate with lead titanate (PMNT) by sputter deposition. The study was aimed at characterizing post-deposition annealed films at various temperatures. We proved full perovskite crystallization from 400 to 750 °C. From dielectric measurements, it is shown that the quality of the material improves gradually in this temperature range to reach a maximum of dielectric characteristics at 700 °C annealing. Dielectric constant reaches 2300 at dielectric maximum for this last film. Materials of different thickness were processed and low temperature annealing was specially studied for possible application in integrated capacitors. Structural, dielectric and ferroelectric characteristics are detailed for PMNT films with 30% lead titanate.

Detection of gold colloid adsorption at a solid/liquid interface using micromachined piezoelectric resonators

Microfabricated piezoelectric resonators have been used in a liquid environment for real time detection of gold colloid adsorption at a solid/liquid interface. Negatively charged gold colloids in suspension in a buffer solution adsorb on the surface of the piezoelectric microresonator passivated with a silicon dioxide layer that has been functionalized with an amino-silane self-assembled monolayer. The mass loading induced by adsorption on the surface of the piezoelectric resonator leads to a change in resonant frequency. Measured frequency shift as a function of time incubation in a colloidal suspension was observed and correlated with the mass of adsorbed gold colloids.

Dry Etching Process on a Conducting Interpenetrating Polymer Network Actuator for a Flapping Fly Micro Robot

In this paper we report on conducting polymer micro-actuators which have been fully patterned using photolithography and plasma dry etching processes. The interpenetrating polymer network (IPN) architecture used in this work resolves interface and adhesion problems which have been reported for traditional conducting polymer-based actuators. Actuator films 17 μm thick can be obtained and then patterned using microfabrication technologies. IPN-actuators were etched to obtain 2*5mm2 beams operating in air. These micro-sized actuators are potential candidates in numerous low frequency applications, including micro-valves, micro-optical instrumentation and micro-robotics. Moreover, due to the rapid response of our IPN architecture, this material has been considered as the main actuator for the flapping wings of an artificial insect.Copyright

REMANENT PIEZOELECTRIC CONSTANT OF PZT THIN FILMS

Abstract The investigation of piezoelectric properties of materials in the thin layer form has become an important task because of the increased range of their applications as actuators and sensors. Pb(Zr, Ti)O3 thin films and the modified compositions have attracted great attention in recent years as promising for use in micro-electro-mechanical systems. The actuator magnitude, is an indirect function of the e31 piezoelectric constant. To determine this constant we use an unusual experimental method. A remanent piezoelectric constant of -4.7 C/m2 was obtained. To show the possible integration of the piezoelectric films in flat silicon ultrasonic micromotors, we have deposited a 3.5 μm thick PZT on square membranes by rf magnetron sputtering. Self polarisation, remanent piezoelectric constant and dielectric permittivity are presented as function of the PZT thickness.

Compositional and microstructural characterization of rfmagnetron-sputtered lead zirconate titanate thin films

Abstract The growth of ferroelectric lead zirconate titanate (PZT) films by rfmagnetron-sputtering using a Pb(Zr,Ti)O3 target is described. This study has been focused on producing perovskite thin (<200nm) films on different substrates. Depositions were perfomed at room temperature and the process gas is pure argon (0·5–3 Pa). The effects of deposition and post-annealing conditions on film composition and microstructure were evaluated using Rutherford Backscattering Spectroscopy (RBS), Nuclear Reaction Analysis (NRA), null ellipsometry and X-ray diffraction. Optimization of process conditions is discussed in terms of stoichiometry, structure and their reproducibility.

Combined polarizing interferometer and optical beam deflection system for MEMS characterization

A potential application for ferroelectric thin films is micro positioning and actuation, as in MEMS devices. The amount of actuation possible is determined by a number of factors: the piezoelectric coefficient d31, geometric factors and the compliance of both the actuator and cantilever and the electric field across the film. It is important for their realization as devices in applications that these micro-actuators are characterized. One such means is to use optical beam deflection (OBD). However, whilst extremely simple to implement, optical beam deflection does not provide an absolute measure of displacement. For absolute displacement measurement, with directional determination, a dual-beam normal incidence polarization interferometer is required. Based upon an interferometer developed in our laboratory to measure the flying height or head-disk spacing in a hard disk drive, an optical system is proposed which enables both an OBD and a polarization interferometer to be combined in one compact system. Details of both systems and are presented and the combined system described.