Lionel Buchaillot

Silicon nitride thin films Young's modulus determination by an optical non destructive method

The purpose of our study is to determine the Youngs modulus of silicon nitride ( Si3N4) thin films. With respect to the experimental material, we use commercially available atomic force microscopy (AFM) microcantilevers. The novelty lies in the procedure used to compare and therefore to validate the experimental results. First, the fundamental mode of Si3N4 thin film microcantilevers is detected by means of the optical beam deflection (OBD) method. The resulting resonant frequency is subsequently introduced into the mechanical theoretical model to extract the value of the Youngs modulus. A numerical modal analysis is performed to validate the experimental results using the same approach as that of the experiment. Finally, the Youngs modulus obtained in this study is compared with those of other studies. The outcome shows that we have obtained a reliable protocol for Youngs modulus estimation.

In-Plane Silicon-On-Nothing Nanometer-Scale Resonant Suspended Gate MOSFET for In-IC Integration Perspectives

A 14-MHz in-plane nanoelectromechanical resonator based on a resonant-suspended-gate (RSG) MOSFET principle and integrated in a front-end process is demonstrated. The devices are in-plane flexural vibration mode beams (L = 10 mum, w = 165 nm, and h = 400 nm) with 120-nm gaps. This letter details the design and process flow fabrication steps. Then, the electrical device characteristics are demonstrated, comprising static and dynamic studies around the resonant frequency. Devices enable the comparison of a pure capacitive detection with the RSG-MOSFET-based detection on the same component, showing a 4.3-dB-huge peak. Due to its output signal amplification and in-IC integration potentialities, the RSG-MOSFET-based detection is ideal for any type of nanoelectromechanical structure displacement detection.

A large stepwise motion electrostatic actuator for a wireless microrobot

An original large stepwise motion electrostatic microactuator for a wireless microrobot using a distributed Ciliary Motion System (CMS) [1] is presented. Coventorware/sup TM/ cosolver simulations have shown x-displacement of 240 nm for one actuation step. Design of the antennas for inductive powering has been optimized in order to maximize the energy transfer. 24 /spl mu/m gold electroplated hollow micro-coils have been fabricated on an epoxy substrate as receiver antennas. Q-factor of 29 at 13.56 MHz and induced voltage up to 100 V on a 1 k/spl Omega/ load has been obtained. Remote actuation of an array of actuators supporting a 0.25 mm/sup 2//380 /spl mu/m-thick piece of silicon has been successfully demonstrated with a pull-in voltage of 80 V.

Ultra-Sensitive Capacitive Detection Based on SGMOSFET Compatible With Front-End CMOS Process

Capacitive measurement of very small displacement of nano-electro-mechanical systems (NEMS) presents some issues that are discussed in this article. It is shown that performance is fairly improved when integrating on a same die the NEMS and CMOS electronics. As an initial step toward full integration, an in-plane suspended gate MOSFET (SGMOSFET) compatible with a front-end CMOS has been developed. The device model, its fabrication, and its experimental measurement are presented. Performance obtained with this device is experimentally compared to the one obtained with a stand-alone NEMS readout circuit, which is used as a reference detection system. The 130 nm CMOS ASIC uses a bridge measurement technique and a high sensitive first stage to minimize the influence of any parasitic capacitances.

Complete System for Wireless Powering and Remote Control of Electrostatic Actuators by Inductive Coupling

This paper proposes a successful asynchronous remote powering and control of electrostatic microactuators, organized in two distributed micro motion systems (DMMS) with the aim of realizing a wireless microrobot. Remote powering of the integrated circuit (IC) and the microelectromechanical systems (MEMS) components is obtained by inductive coupling at 13.56 MHz, and the digital transmission is created by modulating the carrier amplitude by 25%. The system includes a high-voltage controller IC. It provides a link between the power and data on the receiver antenna on one side, and the actuators of the microrobot on the other. The micromachined antenna is designed to optimize the inductive coupling. The main IC building blocks, such as the received signal rectifier/amplifier, the integrated digital processing and the DMMS actuation voltage generation are given in detail. The demonstrator has successfully achieved the remote control and asynchronous operation under 100 V of two arrays of 1700 electrostatic actuators, having a capacity of 2 nF each

A three-dimensional shape memory alloy loop actuator

Shape Memory Alloy (SMA) actuators can produce large displacement/force and are robust against external overload. Their structure is simple because an SMA element serves as both structural and functional parts. This paper deals with deposition of thin films, heat treatment and patterning of titanium-nickel (TiNi) SMA. Microactuators have been fabricated by this process. Typical dimensions of the actuator were 10 /spl mu/m in thickness, 30 /spl mu/m in width and 800 /spl mu/m in length. They produced large displacement up to 300 /spl mu/m, and large force of more than 5 mN was generated thanks to the intrinsic recovery stress of the SMA. A three-dimensional SMA loop actuator unit composed of two SMA cantilevers is widely described. The dimensions of the loop actuator were 1000 /spl mu/m in length and 600 /spl mu/m in height. The loop actuator has been successfully operated. It features repeatable motion up to 20 Hz. The three-dimensional loop actuator is found to be very attractive to perform external work for MicroElectroMechanical Systems (MEMS).

Ultimate technology for micromachining of nanometric gap HF micromechnical resonators

We demonstrate in this paper a fabrication process for the realization of nanometric lateral gap micromechanical resonators. This two-masks self-aligned process relies on surface micromachining of silicon to achieve high aspect ratio lateral capacitive gaps between a mobile resonator and its fixed electrodes down to 60nm. Two structural materials were used for the vibrating parts : Single crystal silicon and disilane-based LPCVD polysilicon. Thanks to this process, resonating devices have been demonstrated, among which lateral clamped-clamped beam resonators, impact-driven resonators, and paralleled identical resonators structures, with resonance frequency ranging from 5MHz to 35MHz.

MEMS Ring Resonators for Laserless AFM With Sub-nanoNewton Force Resolution

A concept of atomic force microscopy (AFM) oscillating sensors using electromechanical silicon microresonators is presented, and imaging capabilities are demonstrated. The microresonators are designed to feature MHz resonance frequencies, and they are batch fabricated using standard silicon microtechnologies. Integrated capacitive transducers allow to drive the resonator and to sense its vibration amplitude. A nanotip is located at a maximum of displacement for sensing near-field forces when interacting with a surface. The device has been mounted on a commercial AFM setup through a dedicated probe holder and a preprocessing electronic circuit. Experiments show that intermittent contact AFM is possible with a tip vibration amplitude of a few nanometers. AFM images have been acquired on silicon micro and nanopatterns. A force resolution of 0.2 nN/√Hz is deduced from the measurements.

High-frequency high-Q micro-mechanical resonators in thick epipoly technology with post-process gap adjustment

This paper presents high-Q high-frequency lateral-mode clamped-clamped beam micro-resonators driven by parallel-plate electrostatic transducers fabricated in a thick epipoly micromachining technology. An innovative approach is employed to reduce an intrinsically high transducer gap value of more then 3.0 /spl mu/m (determined by the need of 15 /spl mu/m thickness structural layer etching) down to 0.2-0.4 /spl mu/m after the fabrication. This is achieved by employing an electrostatic motor that approaches actuating and sensing electrodes close to the resonator. The electrode motor is driven with 30 V DC voltage, without any DC current consumption. Two resonators having a resonance frequency of 10 MHz have been fabricated with gap values of respectively 0.2 and 0.4 /spl mu/m. A comparative analysis of performances of the two resonators is given in the paper.

Totally free-flexible membrane for low voltage MEMS metal contact switch

This paper presents results concerning an electromechanical DC-contact shunt switch based on a patented totally free-flexible metal membrane combined with an associated low temperature surface micromachining fabrication process. The electrostatic actuation enables an average measured actuation voltage of 9.2V for a 5 mum out-of-plane membrane deflection. The switch exhibits low insertion loss (0.32 dB @ 10GHz) with good isolation (>30dB @ 10GHz).