Laboratoire d’analyse et d’architecture des systèmes
C.ARENAS BUENDIA, J.PHILIPPE, D.HENRY, A.RUMEAU, H.AUBERT, P.PONS
Manifestation avec acte : European Microwave Week ( EuMW ) 2017 du 08 octobre au 13 octobre 2017, Nuremberg (Allemagne), Octobre 2017, 5p. , N° 17268
This communication reports the first experimental results obtained from new type of passive Hydrogen-Pressure Dosimeters for the remote measurement of nuclear radiation. Technological and experimental analyses are performed here to demonstrate the proof-of-concept. Radar measurements of irradiated and non-irradiated passive dosimeters are also reported and confirm the feasibility of the remote reading of such passive sensors. A new design is proposed for minimizing the impact of technological inaccuracies on sensors performances and for facilitating the packaging.
I.PASQUET, H.LE TRONG, V.BACO-CARLES, L.PRESMANES, C.BONNINGUE, V.BAYLAC, P.TAILHADES, V.CONEDERA, P.F.CALMON, D.DRAGOMIRESCU, H.CAMON
CIRIMAT, TEAM, MINC, PHOTO
Revue Scientifique : Journal of the European Ceramic Society, 17p., Septembre 2017, https://doi.org/10.1016/j.jeurceramsoc.2017.03.030 , N° 17162
Films of copper and cobalt-iron oxalates were prepared from suspensions of powders in ethane-1,2-diol deposited on glass or polycarbonate substrates. Two-dimensional structures of oxides, resolved on the scale of less than ten micrometers, were formed by laser insolation of these films, using a photolithography machine. The nature of the constitutive phases of the oxides formed tends to show that the laser heating makes it possible to reach locally, temperatures higher than 1000 °C. The oxides formed are thus sintered. The residual oxalate can be removed by washing or dissolving, leaving the oxide structure on its substrate. In spite of a perfectible sintering, the formed structures could interest different technological applications (electronic or magnetic devices, gas sensors, photovoltaic systems…) requiring the shaping of simple or mixed oxides on a scale close to the micrometer. The process of selective laser decomposition of oxalates, could subsequently be suitable for additive manufacturing of 3D parts.
S.CHARLOT, P.PONS, M.DILHAN, I.VALLET, S.BRIDA
TEAM, MINC, Esterline Sensor Gpe
Manifestation avec acte : Eurosensors 2017 du 03 septembre au 06 septembre 2017, Paris (France), Septembre 2017, 2p. , N° 17266
This paper presents the study of gold/gold thermocompression bonding at silicon wafer level. The first samples contains sealing rings and electrical pads and are characterized on pull and shear test showing bond strength similar to silicon/glass anodic bonding (10MPa-80MPa). A sealed cavity and a piezoresistor on a 30µm-thick silicon membrane are added in the second samples. Helium test, membrane deflection and piezoresistor signal monitoring after aging 14 days at 250°C confirm the vacuum stability inside the cavity after bonding. Motivation and results Several bonding techniques [1-5] exist to ensure hermeticity and protection of sensor inside micro-cavities. The analysis of gold thermo-compression bonding performed here contains both sealing ring and electrical contacts. To qualify our process, two different structures are realized to test bond strength (Figure 1) and hermeticity (Figure 2). For both structures, two 4 inches 500µm-thick, double-sided polished silicon wafers with 200nm-thick thermal SiO2 are used. On each wafer, a diffusion barrier followed by 50nm/500 nm Ti/Au evaporated seed layer is deposited. Then a 3µm-thick electroplating gold is deposited inside a patterned resin mold in order to define sealing rings and electrical pads. For the second structure, a square membrane (30µm-thick and 2000µm-side) and piezoresistors are added. For both structures, we used a SUSS-SB6 bonder to perform the thermocompression bonding (420°C, 5,7MPa, 50 minutes). We include spacers between the wafers during alignment to obtain vacuum inside the cavity (5.10-3 mbar). After bonding and dicing, some dies are polished to observe the gold structure at the interface (Figure 3). No delamination is observed between the different materials showing a complete atomic diffusion at the gold interface bonding. Batches of 20 dies are then selected from different wafer areas for pull and shear tests. Most of the dies exhibit cohesive fracture in silicon with tensile strength comparable or superior to silicon/glass anodic bonding (figure 4). Even if pull tests are often used for the qualification of bond strength, this technique don't give reproducible results compared to shear test. High rate leakage through bonding interface has been evaluated with structure 2 by monitoring the membrane deflection several hours after bonding with a mechanical profiler. Measurements show deflection between 4µm and 5µm for 75% of the cells, which is consistent with simulation and technological process variations. In order to check more precisely the leakage, the dies (after breaking the thin silicon membrane) are glued on a special tool where one side of the die is exposed to He and the other side is connected to vacuum (1.10-9 mbar) detector equipment (Figure 5). The mean leak measured by He detector was 10-8 mbar.l/s for the best dies structure bonded which correspond to an excellent hermeticity. The hermeticity reliability has been characterized by following the response of a piezoresistor placed on the membrane after aging at 250°C during 14 days for 6 cells (Figure 6). The piezoreristance shift is lower than 250 ppm for the best cell which correspond to a 75mbar variation inside the cavity.
J.PHILIPPE, C.ARENAS BUENDIA, D.HENRY, A.COUSTOU, A.RUMEAU, H.AUBERT, P.PONS
Manifestation avec acte : Eurosensors 2017 du 03 septembre au 06 septembre 2017, Paris (France), Septembre 2017, 3p. , N° 17264
A new millimetre-wave passive and chipless packaged sensor for wireless pressure monitoring in harsh environment is proposed. This sensor uses a planar microstrip resonator coupled with a high resistivity silicon membrane. The remote interrogation of this sensor is performed from a Frequency-Modulated Continuous-Wave (FMCW) radar. Prototypes have been designed and fabricated using photoresist intermediate layer for the silicon membrane bonding. Radar measurements on two sensors validate a 6dB full-scale response for 1.4 bar overpressure. Depression measurements demonstrate the transducer hermeticity and a measured sensitivity of 1.6% per bar on the millimetre-wave resonant frequency.
I.ARDI, H.CARFANTAN, S.LACROIX, A.MONMAYRANT
PHOTO, IRAP, RIS
Manifestation avec acte : Colloque GRETSI sur le traitement du signal et des images ( GRETSI ) 2017 du 05 septembre au 08 septembre 2017, Juan les pins (France), Septembre 2017, 4p. , N° 17225
Nous nous intéressons à la reconstruction d'images hyperspectrales (HS) à partir d'un nouveau dispositif d'imagerie pilotable. La reconstruction de l'image à partir d'un faible nombre d'acquisitions pour des configurations différentes de l'imageur permet d'éviter l'acquisition de toute l'image HS par balayage. Notre objectif à terme est de rendre ce dispositif adaptatif en fonction de l'objet observé, ce qui nécessite de disposer de méthodes de reconstruction à faible coût calculatoire. Nous nous focalisons ici sur la reconstruction à l'aide de méthodes de pénalisation quadratique, permettant une résolution directe à faible coût, grâce au caractère très creux des matrices. Abstract – We consisder the problem of hyperspectral image reconstruction with a new controlable imaging system. The reconstruction with a small number of images acquired with different configurations of the imager avoids a complete scanning of the hyperspectral cube. Our objective is to exploit this imager along an adaptive scheme, which requires the ability to reconstruct images in near real-time. We focus here on a quadratic penalty reconstruction approach, which provides a fast direct resolution thanks to the high sparsity of the involved matrices.
J.RIONDET, A.COUSTOU, H.AUBERT, P.PONS, M.LAVAYSSIERE, J.LUC, A.LEFRANCOIS
MINC, I2C, CEA-DAM
Manifestation avec acte : Micromechanics and Microsystems Europe workshop ( MME ) 2017 du 23 août au 25 août 2017, Uppsala (Suède), Août 2017, 6p. , N° 17265
Available commercial piezoelectric pressure sensors are not able to accurately reproduce the ultra-fast transient pressure occurring during an air blast experiment. In this communication a new pressure sensor prototype based on a miniature silicon membrane and piezoresistive gauges is reported for significantly improving the performances in terms of time response. Simulation results indicate that it is possible to design a pressure transducer having a fundamental resonant frequency almost ten times greater than the commercial piezoelectric sensors one. 1. Introduction The typical pressure over time during an explosion is shown in Figure 1 [1-2]. First of all, the pressure increases abruptly (with a rise time between 10 ns and 100 ns) from atmospheric pressure to reach the overpressure peak Pmax (several tens of bar depending on the explosive load and the distance from the load). Then the pressure returns back to the atmospheric pressure during a positive phase in 500 µs followed by a negative phase. In order to validate the hydrocode, i.e. numerical simulations describing the shockwave discontinuity, an accurate measurement of the overpressure peak Pmax is required , involving the use of pressure sensors presenting a short time response (<< 1µs). Moreover, the high temperature environment during the explosion (> 1000 °C) makes the real-time dynamic pressure measurement of the blast very challenging. The sensors used for the dynamic measurement of the pressure in harsh environment are usually piezoelectric pressure sensors (Table 1). Air blast experiments were performed at CEA-Gramat center using many piezoelectric sensors mounted on pencil probes to measure the incident pressure, ie with sensor surface parallel to the shock wave propagation (Figure 2). A typical example of the response of such sensors is illustrated in Figure 3. It can be observed that the time response is too long to provide an accurate estimation of the overpressure peak Pmax. The high cutoff frequency of such sensors is approximately 20 % of the resonant frequency. This bandwidth is also degraded by the large dimensions of the sensing part (between 78 mm² and 450 mm²). Moreover typical piezoelectric sensors have a low cutoff frequency (> 0.5 Hz at-5 %) which is too high to follow the overpressure decrease. The objective of this work is to achieve a device with a bandwidth at least ten times greater than the bandwidth of the available commercial piezoelectric sensors. In order to overcome the above-mentioned limitations of these sensors, we report here the design of a new piezoresistive pressure sensor based on a silicon membrane and silicon gauges. The piezoresitive detection has been chosen because it provides a better signal-to-noise ratio than their capacitive counterpart .
Rapport LAAS N°17167, Août 2017
R.KHAYATZADEH, V.AUROUX, A.FERNANDEZ , O.LLOPIS
Manifestation avec acte : Joint conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum ( IFCS-EFTF ) 2017 du 10 juillet au 13 juillet 2017, Besançon (France), Juillet 2017, 4p. , N° 17254
In this paper, a coupled optoelectronic oscillator (COEO) is phase locked to a low noise RF oscillator in order to reduce the phase noise close to the carrier. Biasing current of the optical semiconductor amplifier (SOA) and a varactor diode in the RF part of the COEO are used as two different actuators to perform phase locking. The lock on the optical device is finally simpler and more efficient than the lock on the RF loop. In the second part of this paper, phase noise of the COEO is reduced by more than 15 dB using a chirped Bragg filter that compensates the dispersion of the optical loop.
D.CHAUDY, O.LLOPIS, B.MARCILHAC, O.D'ALLIVY KELLY, J.M.HODE
MOST, UMP Thalès, Thales Airborne Systems
Manifestation avec acte : Joint conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum ( IFCS-EFTF ) 2017 du 10 juillet au 13 juillet 2017, Besançon (France), Juillet 2017, 4p. , N° 17244
Several silicon-germanium bipolar transistors have been measured at cryogenic temperature regarding their gain and phase noise performance. The electrical model of the chosen device has been extracted. Using this model, the phase noise performance of a cryogenic superconductor oscillator has been simulated. The results are very promising, with a phase noise level of-155 dBc/Hz at 1 kHz offset from of a 1 GHz carrier.
O.D'ALLIVY KELLY, Y.LEMAITRE, B.MARCILHAC, D.CHAUDY, J.M.HODE, O.LLOPIS
UMP Thalès, Thales Airborne Systems, MOST
Manifestation avec acte : Joint conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum ( IFCS-EFTF ) 2017 du 10 juillet au 13 juillet 2017, Besançon (France), Juillet 2017, 2p. , N° 17243
High-temperature superconductors (HTS) have shown their potential for analog signal processing at microwave frequencies; they provide high Q resonators, the most critical component of an efficient low phase noise oscillator. Thus, a strategy to outperform state of art quartz oscillators could consist in integrating, in a monolithic block, a planar HTS resonator and a cryo-compatible transistor to build a 1 GHz oscillator. However, mobile systems may require reducing hardware size, weight and power consumption while meeting high performances, controlled costs and reliability needs. We discuss these questions and present our approach to validate the integration of HTS based oscillators into embedded systems.