The paper presents a technique to obtain an electrically-tunable matching between the series and ... more The paper presents a technique to obtain an electrically-tunable matching between the series and parallel resonant frequencies of a piezoelectric MEMS acoustic transducer to increase the effectiveness of acoustic emission/detection in voltage-mode driving and sensing. The piezoelectric MEMS transducer has been fabricated using the PiezoMUMPs technology, and it operates in a plate flexural mode exploiting a 6 mm × 6 mm doped silicon diaphragm with an aluminum nitride (AlN) piezoelectric layer deposited on top. The piezoelectric layer can be actuated by means of electrodes placed at the edges of the diaphragm above the AlN film. By applying an adjustable bias voltage Vb between two properly-connected electrodes and the doped silicon, the d31 mode in the AlN film has been exploited to electrically induce a planar static compressive or tensile stress in the diaphragm, depending on the sign of Vb, thus shifting its resonant frequency. The working principle has been first validated throug...
The Journal of the Acoustical Society of America, 2017
This work presents a lumped parameters equivalent model of condenser microphone based on analogie... more This work presents a lumped parameters equivalent model of condenser microphone based on analogies between acoustic, mechanical, fluidic, and electrical domains. Parameters of the model were determined mainly through analytical relations and/or finite element method (FEM) simulations. Special attention was paid to the air gap modeling and to the use of proper boundary condition. Corresponding lumped-parameters were obtained as results of FEM simulations. Because of its simplicity, the model allows a fast simulation and is readily usable for microphone design. This work shows the validation of the equivalent circuit on three real cases of capacitive microphones, including both traditional and Micro-Electro-Mechanical Systems structures. In all cases, it has been demonstrated that the sensitivity and other related data obtained from the equivalent circuit are in very good agreement with available measurement data.
With the rapid development of system-on-chip (SoC) applications, containing digital and analogue ... more With the rapid development of system-on-chip (SoC) applications, containing digital and analogue parts, the need for fast and reliable on-chip testing methods has become obvious. We present a method for a fast and accurate broadband determination of the behaviour of analogue and mixed-signal circuits. This technique is based on impulse response (IR) evaluation using pseudo-random Maximum-Length Sequences (MLS). This approach provides a large dynamic range and is thus an optimal solution for measurements in noisy environments and for low-power test signals. We will show the algorithms of the MLS generation and of the impulse response calculation which can be easily implemented on-chip.
5th IEEE International Workshop on Advances in Sensors and Interfaces IWASI, 2013
In this work, we will present results showing a feasibility of a MEMS microphone, based on AMS 0.... more In this work, we will present results showing a feasibility of a MEMS microphone, based on AMS 0.35 µm CMOS standard process, with only one step of a sacrificial SiO maskless etching on the substrate front-side. The microphone design, modeling and simulated performance will be stud Fabrication of test structures obtained with a SiO shown as well as characterizations of these test structures.
2011 4th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI), 2011
ABSTRACT Some industrial areas as oil, automotive and aerospace industries, require electromechan... more ABSTRACT Some industrial areas as oil, automotive and aerospace industries, require electromechanical systems working in harsh environments. A solution is to use III-V materials alloys having semiconductor, piezoelectric and pyroelectric properties. These materials, particularly nitrides such as GaN or AlN, enable advanced design of devices suitable for harsh environment. A micromechanical structure based on AlGaN/GaN/AlN cantilevers coupled with a High Electron Mobility Transistor (HEMT) is stress-sensitive and can act as a mechanical sensing device suited to harsh environments. The study of stress distribution after the structure release is necessary to assess its possible influence on the HEMT output. In this article, we propose a method to evaluate these stresses that is based on topology measurements. By coupling numerical modelling and laser interferometry measurements, both intrinsic and residual stresses, respectively the stress before and after release, are calculated. These results are then corroborated by stress measurements using MicroRaman spectroscopy. A residual stress distribution ranging from 140 MPa to 260 MPa is obtained in the HEMT area. However, the influence of this stress can be neglected against the influence of spontaneous polarization in GaN alloys.
Proceedings of the Design Automation & Test in Europe Conference, 2006
Sequence (IRS) that proves better immunity to noise and distortion than MLS. Next, we will illust... more Sequence (IRS) that proves better immunity to noise and distortion than MLS. Next, we will illustrate the application of these techniques for weakly nonlinear, purely nonlinear and strongly nonlinear devices.
17th International Conference on VLSI Design. Proceedings.
... Understanding the sources of the problems can lead to an improvement or the study of device r... more ... Understanding the sources of the problems can lead to an improvement or the study of device reliability, an improvement of fabrication ... This pointer will be next used by the fault simulator to obtain the different faulty design representations required for simulation. ...
2006 International Conference on Advanced Semiconductor Devices and Microsystems, 2006
In this paper, we present the design considerations and the technology process of SAW (surface ac... more In this paper, we present the design considerations and the technology process of SAW (surface acoustic wave) chemical sensors based either on GaAs or GaN structures. These sensors can be used for identifying environmental contaminants and chemical or biological agents in large applications scale; in this study, we aimed at the measurement of low concentrations of gaseous mercury. We describe
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2008
Many medical and biological applications require custom integrated hardware. Infrastructures for ... more Many medical and biological applications require custom integrated hardware. Infrastructures for the design of CMOS and MEMS hardware allow the education and commercialization at a low cost and in a short time. This paper is reviewing the most recent developments at CMP for the manufacturing of ICs and MEMS. These custom hardware vehicles allow to target many medical and biological applications. Examples are provided through the paper. Such infrastructures may help the Medical and Biological community the same way they helped the Microelectronics community at the time of the VLSI revolution.
2010 Fifth IEEE International Symposium on Electronic Design, Test & Applications, 2010
In order to envision fault-tolerant SiPs and SoCs containing RF MEMS switches, this paper studies... more In order to envision fault-tolerant SiPs and SoCs containing RF MEMS switches, this paper studies easily embedded low frequency tests for capacitive switches. The correlation between high frequency (S parameters) and low frequency (envelope of the high frequency signal) responses of a capacitive RF MEMS switch is analysed. This has been done by modeling both the electromechanical and RF behaviours
This paper describes the design of a micromachined ultrasound transducer (MUT). This microsystem ... more This paper describes the design of a micromachined ultrasound transducer (MUT). This microsystem is used in a pulseecho application and it can work as emitter and receiver of ultrasonic signal. The device is fabricated in a 0.8_m CMOS bulk micromachining process, integrating in the same chip a suspended membrane and the associated interface electronics. The membrane is thermally actuated at its resonance frequency (40 kHz) during emission. During reception, a piezoresistive bridge placed on the membrane is used for monitoring the membrane deflections. The resonance frequency of the MEMS is tuned to the emitted frequency by keeping the membrane at the same temperature, achieving then maximum sensitivity. The advantage of this design with respect to capacitive transducers is given by its simplicity: the employment of only one element of the dynamic structure simplifies the design considerations in terms of mechanical stability and membrane damping as well as the fabrication process.
International audienceThis paper presents different transduction principles used in the developme... more International audienceThis paper presents different transduction principles used in the development of micromachined electroacoustic and ultrasonic transducers. These principles are demonstrated through two different devices designed for a silicon compatible technology with post-CMOS MEMS device process. One of them, designed for the narrow frequency band centered at 40 kHz, is based on electro-thermal conversion for the membrane actuation and on the piezoresistive effect for the membrane movement detection. The other device is a microphone based on the electrostatic conversion covering the audible frequency range. We have chosen a low stress cantilever as the microphone movable electrode. Such a solution avoids the residual stress that is often present in typical membranes clamped on edges and allows high microphone sensitivity
ABSTRACT This paper presents a micromachined vibration sensor working in the audible frequency ra... more ABSTRACT This paper presents a micromachined vibration sensor working in the audible frequency range [1-5] kHz that is intended to be used during an ORL (Oto-Rhino-Laryngology) surgery. The sensor must give the surgeon feed back on his intervention related with the middle ear acoustic transmission properties by measuring the ossicles vibration amplitude. Since vibration amplitudes of the lightweight ossicles are very low (from 10 nm to 100 nm), high sensitivity and low mechanical impedance are required. The hand-held device will be easy to position on small middle-ear ossicles (millimeter scale). The use of such a device could be extended to other types of hand-held vibration measuring tools where a low mechanical impedance and high sensitivity are required. An electromechanical equivalent model is used to predict the influence of the sensor on the ossicular chain behaviour. A strain gauge that is suitable for this type of sensor is discussed. Finally, sensor dimensions and mechanical properties are optimised, taking into account specific constraints imposed by the human middle ear on the sensor dynamic behaviour.
We present results for full-electrical characterization of a 64 MHz silicon bulk acoustic resonat... more We present results for full-electrical characterization of a 64 MHz silicon bulk acoustic resonator with quality factor (Q) of 10 4 and achieving an insertion loss of -35dB without depending on sub-micron capacitive gaps. The high transduction results from using thermal actuation in addition to piezoresistive sensing. In contrast to typical capacitive bulk acoustic resonators, both transduction and Q increase when reducing the device thickness. To this effect, our s had 23dB less insertion loss than ones that were 25 thick, with the same lateral dimensions. We also present an equivalent circuit model which we show to be capable of providing a close fit to our experimental measurements.
ABSTRACT This article presents a technique for nonlinear devices characterization and testing by ... more ABSTRACT This article presents a technique for nonlinear devices characterization and testing by identification of the Volterra kernels. After presenting the concept of Volterra modeling, we present a CAT tool based on the Volterra modeling technique. Then we apply the technique for the case-studies of a nonlinear system and a purely nonlinear MEMS cantilever. By finding the Volterra kernels of each of the case-studies we show how they can be used for characterization and test. Through this work, we introduce and discuss the multi-level MLS stimulus generation and response processing necessary to calculate the Volterra kernels. The multi-level stimulus can be generated easily on-chip and the response processing can also be simplified to be implemented on-chip for the purpose of BIST. The use of pseudorandom testing for MEMS characterization has never been addressed in the past to the best of our knowledge.
The paper presents a technique to obtain an electrically-tunable matching between the series and ... more The paper presents a technique to obtain an electrically-tunable matching between the series and parallel resonant frequencies of a piezoelectric MEMS acoustic transducer to increase the effectiveness of acoustic emission/detection in voltage-mode driving and sensing. The piezoelectric MEMS transducer has been fabricated using the PiezoMUMPs technology, and it operates in a plate flexural mode exploiting a 6 mm × 6 mm doped silicon diaphragm with an aluminum nitride (AlN) piezoelectric layer deposited on top. The piezoelectric layer can be actuated by means of electrodes placed at the edges of the diaphragm above the AlN film. By applying an adjustable bias voltage Vb between two properly-connected electrodes and the doped silicon, the d31 mode in the AlN film has been exploited to electrically induce a planar static compressive or tensile stress in the diaphragm, depending on the sign of Vb, thus shifting its resonant frequency. The working principle has been first validated throug...
The Journal of the Acoustical Society of America, 2017
This work presents a lumped parameters equivalent model of condenser microphone based on analogie... more This work presents a lumped parameters equivalent model of condenser microphone based on analogies between acoustic, mechanical, fluidic, and electrical domains. Parameters of the model were determined mainly through analytical relations and/or finite element method (FEM) simulations. Special attention was paid to the air gap modeling and to the use of proper boundary condition. Corresponding lumped-parameters were obtained as results of FEM simulations. Because of its simplicity, the model allows a fast simulation and is readily usable for microphone design. This work shows the validation of the equivalent circuit on three real cases of capacitive microphones, including both traditional and Micro-Electro-Mechanical Systems structures. In all cases, it has been demonstrated that the sensitivity and other related data obtained from the equivalent circuit are in very good agreement with available measurement data.
With the rapid development of system-on-chip (SoC) applications, containing digital and analogue ... more With the rapid development of system-on-chip (SoC) applications, containing digital and analogue parts, the need for fast and reliable on-chip testing methods has become obvious. We present a method for a fast and accurate broadband determination of the behaviour of analogue and mixed-signal circuits. This technique is based on impulse response (IR) evaluation using pseudo-random Maximum-Length Sequences (MLS). This approach provides a large dynamic range and is thus an optimal solution for measurements in noisy environments and for low-power test signals. We will show the algorithms of the MLS generation and of the impulse response calculation which can be easily implemented on-chip.
5th IEEE International Workshop on Advances in Sensors and Interfaces IWASI, 2013
In this work, we will present results showing a feasibility of a MEMS microphone, based on AMS 0.... more In this work, we will present results showing a feasibility of a MEMS microphone, based on AMS 0.35 µm CMOS standard process, with only one step of a sacrificial SiO maskless etching on the substrate front-side. The microphone design, modeling and simulated performance will be stud Fabrication of test structures obtained with a SiO shown as well as characterizations of these test structures.
2011 4th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI), 2011
ABSTRACT Some industrial areas as oil, automotive and aerospace industries, require electromechan... more ABSTRACT Some industrial areas as oil, automotive and aerospace industries, require electromechanical systems working in harsh environments. A solution is to use III-V materials alloys having semiconductor, piezoelectric and pyroelectric properties. These materials, particularly nitrides such as GaN or AlN, enable advanced design of devices suitable for harsh environment. A micromechanical structure based on AlGaN/GaN/AlN cantilevers coupled with a High Electron Mobility Transistor (HEMT) is stress-sensitive and can act as a mechanical sensing device suited to harsh environments. The study of stress distribution after the structure release is necessary to assess its possible influence on the HEMT output. In this article, we propose a method to evaluate these stresses that is based on topology measurements. By coupling numerical modelling and laser interferometry measurements, both intrinsic and residual stresses, respectively the stress before and after release, are calculated. These results are then corroborated by stress measurements using MicroRaman spectroscopy. A residual stress distribution ranging from 140 MPa to 260 MPa is obtained in the HEMT area. However, the influence of this stress can be neglected against the influence of spontaneous polarization in GaN alloys.
Proceedings of the Design Automation & Test in Europe Conference, 2006
Sequence (IRS) that proves better immunity to noise and distortion than MLS. Next, we will illust... more Sequence (IRS) that proves better immunity to noise and distortion than MLS. Next, we will illustrate the application of these techniques for weakly nonlinear, purely nonlinear and strongly nonlinear devices.
17th International Conference on VLSI Design. Proceedings.
... Understanding the sources of the problems can lead to an improvement or the study of device r... more ... Understanding the sources of the problems can lead to an improvement or the study of device reliability, an improvement of fabrication ... This pointer will be next used by the fault simulator to obtain the different faulty design representations required for simulation. ...
2006 International Conference on Advanced Semiconductor Devices and Microsystems, 2006
In this paper, we present the design considerations and the technology process of SAW (surface ac... more In this paper, we present the design considerations and the technology process of SAW (surface acoustic wave) chemical sensors based either on GaAs or GaN structures. These sensors can be used for identifying environmental contaminants and chemical or biological agents in large applications scale; in this study, we aimed at the measurement of low concentrations of gaseous mercury. We describe
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2008
Many medical and biological applications require custom integrated hardware. Infrastructures for ... more Many medical and biological applications require custom integrated hardware. Infrastructures for the design of CMOS and MEMS hardware allow the education and commercialization at a low cost and in a short time. This paper is reviewing the most recent developments at CMP for the manufacturing of ICs and MEMS. These custom hardware vehicles allow to target many medical and biological applications. Examples are provided through the paper. Such infrastructures may help the Medical and Biological community the same way they helped the Microelectronics community at the time of the VLSI revolution.
2010 Fifth IEEE International Symposium on Electronic Design, Test & Applications, 2010
In order to envision fault-tolerant SiPs and SoCs containing RF MEMS switches, this paper studies... more In order to envision fault-tolerant SiPs and SoCs containing RF MEMS switches, this paper studies easily embedded low frequency tests for capacitive switches. The correlation between high frequency (S parameters) and low frequency (envelope of the high frequency signal) responses of a capacitive RF MEMS switch is analysed. This has been done by modeling both the electromechanical and RF behaviours
This paper describes the design of a micromachined ultrasound transducer (MUT). This microsystem ... more This paper describes the design of a micromachined ultrasound transducer (MUT). This microsystem is used in a pulseecho application and it can work as emitter and receiver of ultrasonic signal. The device is fabricated in a 0.8_m CMOS bulk micromachining process, integrating in the same chip a suspended membrane and the associated interface electronics. The membrane is thermally actuated at its resonance frequency (40 kHz) during emission. During reception, a piezoresistive bridge placed on the membrane is used for monitoring the membrane deflections. The resonance frequency of the MEMS is tuned to the emitted frequency by keeping the membrane at the same temperature, achieving then maximum sensitivity. The advantage of this design with respect to capacitive transducers is given by its simplicity: the employment of only one element of the dynamic structure simplifies the design considerations in terms of mechanical stability and membrane damping as well as the fabrication process.
International audienceThis paper presents different transduction principles used in the developme... more International audienceThis paper presents different transduction principles used in the development of micromachined electroacoustic and ultrasonic transducers. These principles are demonstrated through two different devices designed for a silicon compatible technology with post-CMOS MEMS device process. One of them, designed for the narrow frequency band centered at 40 kHz, is based on electro-thermal conversion for the membrane actuation and on the piezoresistive effect for the membrane movement detection. The other device is a microphone based on the electrostatic conversion covering the audible frequency range. We have chosen a low stress cantilever as the microphone movable electrode. Such a solution avoids the residual stress that is often present in typical membranes clamped on edges and allows high microphone sensitivity
ABSTRACT This paper presents a micromachined vibration sensor working in the audible frequency ra... more ABSTRACT This paper presents a micromachined vibration sensor working in the audible frequency range [1-5] kHz that is intended to be used during an ORL (Oto-Rhino-Laryngology) surgery. The sensor must give the surgeon feed back on his intervention related with the middle ear acoustic transmission properties by measuring the ossicles vibration amplitude. Since vibration amplitudes of the lightweight ossicles are very low (from 10 nm to 100 nm), high sensitivity and low mechanical impedance are required. The hand-held device will be easy to position on small middle-ear ossicles (millimeter scale). The use of such a device could be extended to other types of hand-held vibration measuring tools where a low mechanical impedance and high sensitivity are required. An electromechanical equivalent model is used to predict the influence of the sensor on the ossicular chain behaviour. A strain gauge that is suitable for this type of sensor is discussed. Finally, sensor dimensions and mechanical properties are optimised, taking into account specific constraints imposed by the human middle ear on the sensor dynamic behaviour.
We present results for full-electrical characterization of a 64 MHz silicon bulk acoustic resonat... more We present results for full-electrical characterization of a 64 MHz silicon bulk acoustic resonator with quality factor (Q) of 10 4 and achieving an insertion loss of -35dB without depending on sub-micron capacitive gaps. The high transduction results from using thermal actuation in addition to piezoresistive sensing. In contrast to typical capacitive bulk acoustic resonators, both transduction and Q increase when reducing the device thickness. To this effect, our s had 23dB less insertion loss than ones that were 25 thick, with the same lateral dimensions. We also present an equivalent circuit model which we show to be capable of providing a close fit to our experimental measurements.
ABSTRACT This article presents a technique for nonlinear devices characterization and testing by ... more ABSTRACT This article presents a technique for nonlinear devices characterization and testing by identification of the Volterra kernels. After presenting the concept of Volterra modeling, we present a CAT tool based on the Volterra modeling technique. Then we apply the technique for the case-studies of a nonlinear system and a purely nonlinear MEMS cantilever. By finding the Volterra kernels of each of the case-studies we show how they can be used for characterization and test. Through this work, we introduce and discuss the multi-level MLS stimulus generation and response processing necessary to calculate the Volterra kernels. The multi-level stimulus can be generated easily on-chip and the response processing can also be simplified to be implemented on-chip for the purpose of BIST. The use of pseudorandom testing for MEMS characterization has never been addressed in the past to the best of our knowledge.
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Papers by Libor Rufer