Jean-Paul Gilles

Permalloy electroplating through photoresist molds

Abstract Electrodeposited Ni 80 Fe 20 magnetic films are used in storage devices and are usually used for MEMS. In this paper, we present some fundamental results concerning the influence of electrodeposition conditions on the films characteristics. In the first step, permalloy electrodeposition has been studied on copper evaporated films without resist patterns. The growth rate varies linearly as function of the current density (typically 120 nm min −1 for 10 mA cm −2 ). The variation of the alloy composition with deposition parameters is consistent with the so-called anomalous deposition effect, i.e., a preferential deposition of iron. The composition is the same for films with thickness in the range 0.6–20 μm and the Fe concentration decreases with current density. An alloy Ni 80 Fe 20 with a density close to the bulk value is obtained for a current density of 14.5 mA cm −2 . Characterization of magnetic properties with a vibrating magnetometer shows that good properties can be obtained (coercivity=0.35 Oe for a thickness of 600 nm). These results are applied to the patterning of permalloy by electrodeposition through photoresist molds.

Effects of direct and pulse current on copper electrodeposition through photoresist molds

In this paper, electrodeposition of copper films and copper lines with direct and pulse currents is compared. In the first step, electrical and physicochemical characterizations of the copper films are realized, and the optimized electrodeposition parameters are so determined. The use of pulse reverse current is also investigated. In the second step, these parameters are applied to micromolding. Copper lines are electro-deposited and compared in order to determine the more suitable current mode for micromolding.

Development of a short pulsed corona discharge ionization source for ion mobility spectrometry

The development of a pulsed corona discharge ionization source and its use in ion mobility spectrometry (IMS) is presented. In a point-plane electrode geometry, an electrical pulse up to 12 kV, 150 ns rise time and 500 ns pulse width was used to generate a corona discharge in air. A single positive high voltage pulse was able to generate about 1.6×1010 ions at energy consumption of 22μJ. Since the temporal distribution of ions is in a pulsed form, the possibility of removal the ion gate has been investigated. By purposely arranging the interface between discharge field and drift field, nearly 107 positive ions were drawn into the drift region with absence of the ion gate after every single discharge. The positive spectrum of acetone dimer (working at room temperature) was obtained with a resolving power of 20 by using this configuration. The advantages of this new scheme are the low power consumption compared with the dc method as well as the simplicity of the IMS cell structure.

Effects of a loop array layer on a micro-inductor for future RF MEMS components

Tunable micro-inductors can be designed controlling magnetic coupling coefficient. This paper presents the inductance variation produced by loops strongly magnetically coupled with a micro-inductor. A compact lumped element model, based on the geometry, gives result in good agreement with measurements in the RF frequency range. Then, this model will be applied to the study of the tunable MEMS inductor described below.

RF MEMS: Silicon micro-mechanical capacitive structures

The general study is dedicated to Wireless Sensor Networks. The idea is to associate micro-mechanical and microwave communication functions to exchange information between a remote sensor and a base station [1]. A specific part of this project concerns the conception, realisation, and characterisation of a passive microwave frequency shifter used for back-modulation around 2 GHz. The interesting point was to develop this function with an integrated silicon micro-mechanical rotating structure. The paper describes the prototype of the RF MEMS already developed in ESIEE laboratory. And we insist on the microwave measurements performed and the associated equivalent models.

RIBE of thick aluminum films for microelectromechanical devices

A low-temperature etching process of thick aluminum films is proposed. A reactive ion beam etching (RIBE) process with pure chlorine has provided the basis for this investigation. An etch rate of about and nearly vertical sidewalls have been obtained. The method can be useful to define small local patterns in addition to other elaboration processes such as electrodeposition.