Bernard Legrand

Bernard Legrand
Laboratory for Analysis and Architecture of Systems | LAAS · Department of Nano Bio Technologies (MNBT)

PhD

About

198
Publications
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5,529
Citations

Publications

Publications (198)
Article
Atomic force spectroscopy and microscopy are invaluable tools to characterize nanostructures and biological systems. State-of-the-art experiments use resonant driving of mechanical probes, whose frequency reaches MHz in the fastest commercial instruments where cantilevers are driven at nanometer amplitude. Stiffer probes oscillating at tens of pico...
Article
Full-text available
Atomic force microscopy (AFM) has been consistently supporting nanosciences and nanotechnologies for over 30 years and is used in many fields from condensed matter physics to biology. It enables the measurement of very weak forces at the nanoscale, thus elucidating the interactions at play in fundamental processes. Here, we leverage the combined be...
Article
Silicon ring-shaped micro-electro-mechanical resonators have been fabricated and used as probes for dynamic atomic force microscopy (AFM) experiments. They offer resonance frequency above 10 MHz, which is notably greater than that of usual cantilevers and quartz-based AFM probes. On-chip electrical actuation and readout of the tip oscillation are o...
Article
Full-text available
Semiconductor quantum boxes (QB's) are well suited to cavity quantum electrodynamic experiments in the solid state because of their sharp emission. We study by time-resolved photoluminescence InAs QB's placed in the core of small-volume and high-finesse GaAs/AlAs pillar microresonators. A spontaneous emission rate enhancement by a factor of up to 5...
Conference Paper
Full-text available
We report the simulation, design, fabrication and performance assessment of capacitive MEMS, carrying out contactless electromechanical computing with ultra-low-power consumption. The novel concept is implemented on silicon using on-purpose differential comb-drive actuators. This shift in the paradigm allows near-zero power dissipation by asymptoti...
Preprint
Atomic force microscopy (AFM) has been constantly supporting nanosciences and nanotechnologies for over 30 years, being present in many fields from condensed matter physics to biology. It enables measuring very weak forces at the nanoscale, thus elucidating interactions at play in fundamental processes. Here we leverage the combined benefits of mic...
Article
One prerequisite for high-speed imaging in dynamic-mode atomic force microscopy (AFM) is the fast demodulation of the probe signal. In this contribution, we present the amplitude and phase estimation method based on the acquisition of four points per oscillation, with the sampling frequency being phase-locked on the probe actuation. The method is i...
Preprint
Atomic force spectroscopy and microscopy (AFM) are invaluable tools to characterize nanostructures and biological systems. Most experiments, including state-of-the-art images of molecular bonds, are achieved by driving probes at their mechanical resonance. This resonance reaches the MHz for the fastest AFM micro-cantilevers, with typical motion amp...
Article
Full-text available
We show that nanometer-scale dielectric thin films can act as efficient electromechanical transducers to simultaneously drive and sense the vibration of the first flexural mode of micro/nano-cantilevers. Here, 16 μm-long, 5 μm-wide and 350 nm-thick cantilevers are actuated by a 15 nm-thick silicon nitride layer, and electrically detected by charge...
Article
Full-text available
In this work, we use the micro-masonry technique to fabricate nanoplate resonators with integrated electrostatic actuation and capacitive detection in a few steps. Our approach is an alternative solution to the current fabrication methods used to create membranes and plates that usually rely on the selective etching of a sacrificial layer. Highly d...
Conference Paper
We show that a nanometer-thick high-K material can be used as an electromechanical transducer to actuate the flexural mode of micro/nanoresonators. In this study, a 15 nm silicon nitride layer is employed on top of 320 nm thick silicon beams. The devices, smaller by 2 orders of magnitude than in previous studies [1], are successfully driven into vi...
Conference Paper
We propose a method for the experimental determination of the effective mass and stiffness of a micro mechanical resonator using optical interferometry in a Fabry-Perot configuration. The method relies on the spectral analysis of the photodiode signal, which is ruled by the Jacobi-Anger expansion, allowing the absolute calibration of the vibration...
Article
We show that the capacitive transduction of a MEMS device using a setup based on a microwave detection scheme achieves the measurement of the thermomechanical noise spectrum of a high-frequency (>10 MHz) high-stiffness (>105 N/m) resonator, reaching the outstanding displacement resolution of 1 fm/√Hz. This result paves the way for vibrating sensors...
Patent
A system for detecting responses of a MEMS resonator device includes first and second signal sources, a signal divider and a frequency mixer. The first signal source provides a first signal and the second signal source provides a second signal that electrostatically drives the MEMS resonator device, causing mechanical vibration. The signal divider...
Article
In order to effectively prompt the resonance frequency and the quality factor of atomic force microscope (AFM) probes simultaneously, a novel oscillating probe based on a I2 shaped MEMS resonator was conceived, designed, fabricated and evaluated. To further improve the imaging capability of this kind of probe, structure design and measurement impro...
Article
Full-text available
Advantages of using nanoscale membrane and plate resonators over more common cantilever shapes include higher quality factor (Q factor) for an equivalent mass and better suitability to mass sensing applications in fluid. Unfortunately, the current fabrication methods used to obtain such membranes and plates are limited in terms of materials and thi...
Article
Full-text available
In order to effectively increase the resonance frequency and the quality factor of atomic force microscope (AFM) probes, a novel oscillating probe based on a dog-bone shaped MEMS resonator was conceived, designed, fabricated and evaluated. The novel probe with 400 μm in length, 100 μm in width and 5 μm in thickness was enabled to feature MHz resona...
Article
Full-text available
We present a method to characterize sub-10 nm capacitors and tunnel junctions by interferometric scanning microwave microscopy (iSMM) at 7.8 GHz. At such device scaling, the small water meniscus surrounding the iSMM tip should be reduced by proper tip tuning. Quantitative impedance characterization of attofarad range capacitors is achieved using an...
Conference Paper
Most of commercial Atomic Force Microscope (AFM) oscillating probes use micrometric cantilevers that can make measurement with piconewton force resolution under vacuum. However, the flexure vibration cantilevers suffer from a degradation of both resonance frequency and quality factor when operating in liquids. Moreover, the additional laser set-up...
Article
Nous présentons une façon de caractériser quantitativement des capacités sous échelle de 10 nm à l'aide d'un scanning-microwave-microscope modifié avec un interféromètre (iSMM). Des milliers de capacités à l'échelle nanométrique (nanoplots) et un kit de capacités de calibrages sont intégrés et scanné simultanément. Ceci permet la génération d'histo...
Article
The design of Micro Electro Mechanical Systems (MEMS) is often based on the use of costly trial and error method which depends highly on the technical skills of the involved engineers. The drawback of such a procedure is to lead to sub-optimal designs and poor performance at the end. Some research works on dedicated optimization tools have begun a...
Article
We report on an adjustable interferometric set-up for Scanning Microwave Microscopy. This interferometer is designed in order to combine simplicity, a relatively flexible choice of the frequency of interference used for measurements as well as the choice of impedances range where the interference occurs. A vectorial calibration method based on a mo...
Article
Microwave reflectometry is proposed as an effective technique to detect the vibration of capacitively transduced microelectromechanical resonators. The transducer capacitor is probed by an incident wave, which is reflected being modulated by the time variations of the resonator displacement. Calculations demonstrate that the sensitivity of the tech...
Article
n° de priorité : FR20120050066 20120104 ; également publié en tant que : US2013169341 (A1) 2013-07-04 ; GB2498251 (A) 2013-07-10
Conference Paper
The paper proposes a novel technique for measuring the vibration of capacitive microelectromechanical resonators. Based on microwave reflectometry in the gigahertz range, the technique offers signal-to-noise ratio greater than 100 dB for the studied device and it rejects any parasitic crosstalk due to stray capacitances. Experiments demonstrate tha...
Article
Scanning probe microscopes (SPMs) allow scientists to image, characterize and even manipulate material structures at exceedingly small scales including features of atomic dimensions. Although most microelectronics devices operate at high frequency, SPMs have mainly been used with electrical excitation at DC (Conducting Atomic Force Microscope) or k...
Article
Full-text available
A new concept of atomic force microscope (AFM) oscillating probes using electrostatic excitation and piezoresistive detection is presented. The probe is characterized by electrical methods in vacuum and by mechanical methods in air. A frequency-mixing measurement technique is developed to reduce the parasitic signal floor. The probe resonance frequ...
Conference Paper
Full-text available
In order to effectively increase the resonance frequency and the quality factor of atomic force microscope (AFM) probes, a novel oscillating probe based on a dog-bone shaped MEMS resonator was conceived, designed, fabricated and evaluated. The novel probe with 400 μm in length, 100 μm in width and 5 μm in thickness was enabled to feature MHz resona...
Article
Electrical impedance characterization at the nanoscale is a challenge for beyond CMOS investigations and for understanding the electronic properties of nanomaterials. Among the various scanning probe microscopes, Scanning Microwave Microscope (SMM) is of particular interest because it combines nanometric lateral resolution of atomic force microscop...
Conference Paper
A new concept of Atomic Force Microscope (AFM) oscillating probes using electrostatic excitation and piezo-resistive detection is presented. The probe is characterized by electrical methods in a vacuum chamber and by mechanical methods in air. The frequency-mixing measurement technique is developed to reduce the parasitic signal level. These probes...
Article
We present electron-beam lithography results on an AznLOF2020 UV negative tone resist. This study aims to define electron-beam lithography parameters compatible with microelectromechanical systems/nanoelectromechanical systems fabrication. Usually, one of the properties of the resist material is improved to the detriment of another. Resist properti...
Article
My research activities have covered since 1996 the fields of nanosciences, semi-conductor physics, micro and nanotechnologies and MEMS/NEMS (Micro/NanoElectroMechanical Systems). In particular, I joined the Silicon Microsystems department of IEMN in October 2000 and I worked on electromechanical microresonators for applications in signal processing...
Article
Full-text available
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...
Article
For the first time, 100nm side DNA origami squares have been imaged using 10.9MHz laserless AFM MEMS probe. This sensor takes advantage of the high resonance frequency of a silicon bulk mode resonator integrating a nano-tip fabricated in batch process. After integration in a commercially available AFM set-up with a modified probe holder, the AFM ME...
Article
A new concept of Atomic Force Microscope (AFM) oscillating probes using electrostatic excitation and piezoresistive detection is presented. The probe is characterized by electrical methods in vacuum chamber and by mechanical methods in air. The frequency-mixing measurement technique is developed to reduce the parasitic signal level. These probes re...
Article
Habilitation à diriger des recherches en Sciences Physiques, Université de Lille 1, 8 juin
Article
The history of MEMS resonators other than comb-drive is fairly short, 15 years at most. At the beginning, researchers together with engineers had the dream to replace quartz by silicon and they started working on resonators designed for filter application in cell phones. Today, MEMS resonators are surpassed by bulk acoustic wave technology and conf...
Conference Paper
This paper reports on the description of a new high force-resolution microgripper with large jaw displacement, electrostatically actuated by a comb-drive and instrumented with an integrated differential capacitive displacement sensor. This microgripper has been non-intuitively designed using a multi-objective optimization method, to reach the best...
Article
This paper presents the optimization of polysilicon doping and metallization to form ohmic contact with etching resistance. Indeed, polysilicon doped by ion implantation and ohmic contacts are an important and interesting part of integrated circuit technology or MEMS and NEMS. LPCVD-polysilicon doping parameters, such as ion energy, dose, and annea...
Conference Paper
We report here on high resonance frequency AFM probes based on MEMS bulk mode resonators. They consist on silicon ring resonators with capacitive transducers vibrating in the in-plane elliptic mode. Nano-tips placed at the maximum of vibration are fabricated in batch process. After electrical and optical characterizations, chips supporting the reso...
Conference Paper
A new concept of Atomic Force Microscope (AFM) oscillating probes using electrostatic excitation and piezo-resistive detection is presented. The probe is characterized by electrical methods in vacuum chamber and by mechanical methods in air. The mixer measurement technique is developed to reduce the parasitic signal level. These probes resonance fr...
Article
In this letter, we present a materials selection based on the Ashby’s methodology to optimise the choice of bridge’s material in radio-frequency applications. Two material indices are defined to minimize the intrinsic residual stress due to sputtering deposition process and to maximize the quality factor, respectively. The selection procedure gives...
Article
We present a lithography process using electron beam lithography with an optical resist AZnLOF 2020 for pattern transfer. High-resolution 100keV electron beam lithography in 400nm layers of negative resist AZnLOF 2020 diluted 10:4 with PMGEA is realized. After the electron beam lithography process, the resist is used as a mask for reactive ion etch...
Article
This paper presents the correlation between the optical properties and the chemical and electrical properties of amorphous silicon nitride (SiNX:H) films prepared by reactor Plasma-Enhanced Chemical Vapor Deposition (PECVD). The effects of temperature and mixture of gases (NH3/SiH4/N2) on these dielectric films are investigated in this study. Silan...
Article
Full-text available
Atomic force microscopy (AFM) is a powerful imaging tool with high-resolution imaging capability. AFM probes consist of a very sharp tip at the end of a silicon cantilever that can respond to surface artefacts to produce an image of the topography or surface features. They are intrinsically passive devices. For imaging soft biological samples, and...
Article
A new approach for the fabrication of large contour-mode single-crystal silicon resonators has been demonstrated without the use of SOI substrates. Twenty-four-megahertz disk resonators have been built thanks to industrial facilities dedicated to the integration of passive components on silicon and exhibit a good compromise between the quality fact...
Article
We report here on results of AFM microscopy using laserless MEMS based probes. This new concept of atomic force microscope (AFM) probes using bulk-mode silicon resonators was previously presented [1]. They consist on silicon ring resonators with capacitive transducers and integrated sensing nanotip. We have also demonstrated that these probes are s...
Article
We present an integrated force probe based on a silicon bulk-mode MEMS resonator. This device uses a silicon ring with symmetrical tips vibrating in the elliptic vibration mode. The tips enable us to make mechanical interactions with surfaces or external objects. Both excitation and detection of the resonator are integrated thanks to electrostatic...
Conference Paper
A new approach for the fabrication of large contour-mode single-crystal silicon resonators has been demonstrated without the use of SOI substrates. 24-MHz-disk resonators have been built thanks to industrial facilities dedicated to the integration of passive components on silicon. They exhibit a good compromise between the quality factor Q higher t...
Article
Full-text available
Here we describe a simple and effective approach to make silicon-based-nanowires structured materials which can be utilized in a range of high technology electronic devices. The strategy for achieving this objective is to create platforms by lithographic patterning on which the diffusion length of reactive species is controlled during the subsequen...
Article
We have previously reported on a new concept of atomic force microscope (AFM) probes using bulk-mode silicon resonators. We report here measurements of interaction between a surface and the vibrating tip of the resonator. In particular, the tip oscillation amplitude versus the probe-sample distance has been acquired for various surface materials. T...
Article
In this paper, we present the design, fabrication, and operation of a two-dimensional (2-D) microconveyance system. Conceptually, this system was designed as a mechanical part of an autonomous decentralized system composed of integrated micro actuator-sensor-controller cells. The presented system is a 2-D ciliary motion system (2-D CMS) composed of...
Article
n° de priorité : FR20070003161 20070502 ; également publié en tant que : WO2008148951 (A1) 2008-12-11 ; EP2150799 (A1) 2010-02-10 ; JP2010526284 (A) 2010-07-29 ; US2010205698 (A1) 2010-08-12 ; US8091143 (B2) 2012-01-03 ; FR2915803 (B1) 2012-06-08 ; JP5208201 (B2) 2013-06-12
Article
We describe electrostatically actuated silicon nanotweezers which are intended for the manipulation and characterization of filamentary molecules. The microelectromechanical system consists of a pair of opposing tips whose distance can be accurately adjusted by means of an integrated differential capacitive sensor. The fabrication process is based...
Conference Paper
The resonant sensing technique is highly sensitive, has the potential for large dynamic range, good linear-ity, low noise and potentially low power. The detection principle is based on frequency change that is induced by rigidity changes in the resonator. In order to compensate the loss of performances when scaling sensors down to NEMS, it proves c...
Article
Full-text available
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,...
Conference Paper
Full-text available
The paper reports on in-plane nanometer scale resonators fabricated on 8 inch industrial tools, with a process based on the advanced CMOS Front End Silicon On Nothing Technology. The aim is to propose totally integrated time reference functions realized by small size NEMS resonators. The measurement set-up, simulation and experimental results in th...
Article
Full-text available
This paper presents results about fabrication and operation of electrostatic actuators in liquids with various permittivities. In the static mode, we provide experimental and theoretical demonstration that the pull-in effect can be shifted beyond one third of the initial gap and even be eliminated when electrostatic actuators are operated in liquid...
Article
Silicon microtechnology is used to fabricate microcantilever based nanoelectrospray emitter chips. The chips are composed of beam-based microcantilevers which form a microfluidic capillary slot terminating in a tip having micrometric dimensions. An original combined microfluidic and micromechanical analysis takes into account microfluidic capillary...
Article
Full-text available
This paper presents an original piezoresistive strain gauge architecture based on two polysilicon layers able to sense in-plane strain. These gauges are electrically isolated from the external environment in order to be used in liquids. The presented design is based on three optimization keypoints, which one of these allows the reduction of the bea...
Article
Single-molecule micromanipulations have provided information that has been awaited for a long time. However, these experiments relying on optical tweezers (OT) or magnetic tweezers (MT) have a low throughput since the molecular preparation is done one at a time. In order to move towards systematic biological or medical analysis, micro-nano-electrom...
Article
Full-text available
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...