M. Dilhan

University of Toulouse, Tolosa de Llenguadoc, Midi-Pyrénées, France

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Publications (26)22.16 Total impact

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    ABSTRACT: The BPN is a negative photoresist, sensitive in the UV at 365 nm and was previously dedicated for Wafer Level Packaging applications. This photoresist offers the advantage of forming thick layers; however, it suffers from low aspect ratio (2:1 declared by the supplier). This work reports the BPN’s technological process that allows forming 200–800 μm thick molds for electroplating purposes. Our results revealed an aspect ratio as high as 17:1 while having vertical sidewalls using conventional photolithography.
    Microsystem Technologies 10/2014; 20(10-11). · 0.83 Impact Factor
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    ABSTRACT: The integration of passive components on silicon for future dc-dc converter applications is still a challenging area of research. This paper reports the microfabrication of a fully integrated filter containing a spiral inductor on top of a 3-D capacitor. A thin magnetic shielding layer is introduced between the two components demonstrating that losses caused by the inductor in the capacitor area are reduced, thus increasing the maximum working frequency of the whole component. The fabricated filter was characterized in a test circuit (buck-type converter).
    IEEE Transactions on Power Electronics 09/2011; · 5.73 Impact Factor
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    ABSTRACT: This work deals with recent advances in the microfabrication process technology for medium to high-aspect ratio structures fabricated by UV photolithography using different kinds of photoresists. The resulting structures were used as molds and will be transformed into metal structures by electroplating. Two types of photoresists are compared: epoxy-based (negative) SU-8 and acrylate-based (negative) Intervia BPN. This work was prompted by the need to find an alternative to SU-8 photoresist which is difficult to process and remove after electroplating. The results presented in this paper open up new possibilities for low-cost processes using electroplating in MEMS applications.
    Proc SPIE 03/2011;
  • LIN J, BOURRIER D, DILHAN M, DURU Paul
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    ABSTRACT: The objective of the present work is to investigate experimentally the deposition of micron-sized particles onto the surface of a microsieve membrane, which consists in a thin screen with patterned circular holes. A dilute suspension of spherical, monodisperse, polystyrene particles flows at an imposed flow rate through the membrane, in a frontal filtration mode i.e., the flow direction is perpendicular to the membrane. The particle-to-pore diameter ratio is inferior to one. The particle and flow Reynolds numbers are both smaller than 0.1 for the flow regimes investigated in the present study. The particles are non-Brownian, inertialess, and their buoyancy is negligible. Direct visualizations of the membrane are made using video microscopy. A statistical analysis of the particle deposition locations, based on an automatic processing of video images of the membrane surface recorded during the experiment, is made possible by the periodicity of the pore distribution. Experiments show the existence of two preferential locations for particle deposition, for the whole range of flow rates investigated in the present study and the three microsieve patterns used. This puzzling result is discussed in the light of earlier theoretical and numerical simulations works, dealing with the low Reynolds number motion of a single particle in the vicinity of a pore, in the presence of physicochemical interactions between the particle and the membrane surface.
    Physics of Fluids 01/2009; · 1.94 Impact Factor
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    ABSTRACT: In this work, we present the results of our investigations of an RF nanoswitch device based on nanowires array. The nanowires are used to make a DC contact between the signal line of a CPW line and its ground. Silicon is used as a substrate. The switch is formed by the nanowire and the pillar.The design of a RF NEMS based on vertical metallic nanowires array shows a good performance up to 27 GHz.
    Semiconductor Device Research Symposium, 2007 International; 01/2008
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    ABSTRACT: For applications such as computers, cellular telephones and Microsystems, it is essential to reduce the size and the weight of DC-DC converters. To miniaturize passive components, micromachining techniques provide solutions based on low-temperature process compatible with active part of the converter. This paper deals with the integration on silicon of "spiral-type" inductor topology. Electroplating techniques are used to achieve the copper conductor and the CoNiFe laminated magnetic core and several investigations on the electroplating bath's parameters have been realized in order to obtain the adequate magnetic properties. Finally, a 1muH micro-inductor prototype has been characterized.
    Proc SPIE 01/2008;
  • 2008 MRS Fall Meetin; 01/2008
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    ABSTRACT: This paper deals with the development of a micro-interconnection technology suitable for the elaboration of RF-NEMS (Nano-ElectroMechanical Systems) varactors. It aims to present an extension of RF MEMS concept into nano-scale domain by using multi-walled carbon nanotubes (MWCNT) as movable part instead of micrometric membranes into reconfigurable passive circuits for microwave applications. For such a study, horizontal configuration of the NEMS varactors has been chosen and is commented. The technology is established to fulfill several constraints, technological and microwave ones. As far as technological requirements are concerned, specific attentions and tests have been carried out to satisfy: • Possible and later industrialization. No e-beam technique has been selected for RF NEMS varactor elaboration. Lateral MWCNT growth performed on a Ni catalyst layer, sandwiched between two SiO2 layers, showed feasibility of suspended MWCNT beam. • High thermal budget, induced by the MWCNT growth by CVD (Chemical Vapor Deposition), at least to 600°C. All the dielectric and metallic layers, required to interlink the nano world with the micrometric measurements one, have been studied accordingly. Consequently, the order of the technological steps has been identified. About microwave and actuation specifications (targeted close to 25V), the minimization of losses and actuation voltage implies large layer's thicknesses compared to the CNT diameter. Several specific technological issues are presented in this paper, taking care of both technological and microwave compatibility to go toward RF NEMS varactor's elaboration.
    01/2008: chapter Proc. SPIE 7037, Carbon Nanotubes and Associated Devices: pages 3719-3719;
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    ABSTRACT: This paper investigate the dielectric charging mechanisms in Si<sub>3</sub>N<sub>4</sub> thin films versus different elaboration conditions and different characterization method. Transient currents measurements in PECVD SiNx were performed versus electrical field, temperature and time. These results suggest a dominant conduction mechanism and allow to predict the amount of charge injected into the dielectric and the charge/discharging kinetics processes. The deposition parameters effects, evaluated by FTIR, in order to identify the chemical bond in the dielectric, can explain the charging behavior. Injection and detection of electrical charges by atomic force microscopy at the nanometer scale can be used for studying the dynamic and the propagation of the deposited charges. This observation coupled to transient currents measurements, and FTIR,-can give rules for the best dielectric choice for this particular application.
    Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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    ABSTRACT: Liquid crystalline thin films elastomers that are able to bind pesticides have been developed. The synthesis involves grafting mesogen and crosslinkable groups on a polysiloxane chain in the presence of a template molecule. The molecular imprinted material is obtained after thin film deposition, UV crosslinking and washing. Experiments of readsorption of pesticide are presented. Development of a multisensor platform based on thermal and capacitive sensors is described and tests of deposition of the polymer film are presented.
    Talanta 06/2006; 69(3):757-62. · 3.50 Impact Factor
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    ABSTRACT: We present in this paper trends and technologies for the integration of inductors for DC-DC microconverters. In particular, we present the fabrication steps of different structures as a function of the application: planar inductors for low power consumption, and 3D magnetic inductors for higher power. These devices are achieved using low temperature fabrication processes based in photolithography or and electroplating techniques.
    Industry Applications Conference, 2005. Fourtieth IAS Annual Meeting. Conference Record of the 2005; 11/2005
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    ABSTRACT: This paper describes the fabrication steps of a spiral-type inductor designed for power electronics conversion. Realized on silicon wafer and using photolithography and electroplating techniques, this microinductor is composed of a copper spiral conductor sandwiched between two iron-nickel laminated magnetic layers. Furthermore, specific devices have been realized in order to characterize the magnetic material
    Power Electronics and Applications, 2005 European Conference on; 01/2005
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    ABSTRACT: The market of portable instruments is growing more and more. For applications such as computers, cellular phones and microsystems, it is essential to reduce size and weight of electronic devices, including power unit supplies associated with these products. This evolution will require high efficiency on-chip DC-DC converters providing low voltage for the various Ics. Therefore, fabrication of magnetic components dedicated to power conversion becomes necessary. To miniaturize inductors, the micromachining techniques provide solutions based on low-temperature process compatible with active part of the converter. In this paper, a "spiral type" inductor topology designed for power electronics application is investigated. Thick resist molds photolithography and electroplating techniques are used to achieve the copper conductor and the NiFe laminated magnetic core.
    Proc SPIE 01/2004;
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    ABSTRACT: In the fast growth context of micro-electromechanical systems (MEMS) applications, an important improvement of power supplies "power-to-weight" ratio can be obtained through the integration of magnetic storage elements with their associated electronic environment. These components are usually used to transfer and store high energy densities with high magnetic flux. But up until now, integrated devices with these inductive elements were mainly limited by low inductance and current values. To make optimised new designs and achieve realisation of such inductive elements, we propose a new complete methodology, illustrated through a micro-machined square planar inductor. Indeed, after defining specifications (power, inductance value, frequency, geometrical dimensions), a mathematical method is used to define a first geometrical parameters set. To achieve it, several simulations are conducted with CAD tools dedicated to MEMS technology. Our method is based on a new specific last nano-imprint technology we have developed in our laboratory and adapted, in parallel, to our application
    Circuits and Systems, 2002. ISCAS 2002. IEEE International Symposium on; 02/2002
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    ABSTRACT: Compactness, complexity of the interconnections and specific packaging, which are characteristics of Microsystems (MEMS), rule out the use of statistical procedure to assess reliability in space applications. Predictable reliability is the method recommended in this paper that uses a similar approach as CALCE already did for hybrid and microelectronic circuits. This method based on a failure mechanism approach is recalled at first and an example to illustrate this procedure based on the evolution of material crystal properties under radiation is presented.
    Proc SPIE 08/1999;
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    ABSTRACT: The objective of the MICROMED CNRS project is the design of a complete microsystem usable in the treatment in vivo of hypertensives. The microsystem which corresponds with this objective includes different elements such as pressure sensors, a drug reservoir, a monitoring chip and a drug delivery system that necessitates the use of a dosing micropump able to deliver daily does of few microliters in several shots. We will focus here on the micropump:microfabrication technology, assembly and test. The fact that the fluid actuating membrane, the input and output fluid gates, and the two passive microvalues are together on a single silicon chip of 1 cm3 area makes this pump original. The fabrication technology combines the techniques of microelectronics and MEMS: micromachining for the square membrane and the fluid gates, sacrificial oxide layers and LPCVD polysilicon deposition for the microvalves. The assembly of the different parts is based on existing techniques like anodic bonding, gluing with adhesive films...we have investigated the fabrication of the micro pump with an electrostatic actuation. Tests are in progress for the first prototypes on a specific experimentation set- up in order to: (i) study the flowing of different fluids into the pump, (ii) study the directionality of the valves by plotting the flow rate/pressure (Phi) (P) diagram, (iii) study the pump functionality.
    Proc SPIE 03/1999;
  • V Conédéra, N Fabre, M Dilhan
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    ABSTRACT: The fabrication of micro electro mechanical systems by electrodeposition inside resist moulds has provided much interest in recent years. In this paper, we propose a method to optimize the lithography process of a thick positive photoresist. This technique is based on the variation of transparency of the photoresist during exposure. During exposure the absorption of the light-sensitive compound decreases due to its conversion into indene carboxylic acid. A very good aspect ratio (height:width) of up to 10:1 and high edge steepness has been obtained from one coat and one UV exposure.
    Journal of Micromechanics and Microengineering 12/1998; 7(3):118. · 1.79 Impact Factor
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    ABSTRACT: The surface contamination was known to affect the roughening during anisotropic etching. We studied the role of the initial surface states of silicon after different cleaning treatments (hydrogen-saturated, fluorine-saturated) over the way the etching proceeds. We investigated three types of ultimate-cleaning solutions after the standard RCA treatment: HF:H<sub>2</sub>O 1:10 (followed by DI water rinsing and drying), HF:C<sub>2</sub>H<sub>5</sub>OH 1:10 (dried without any further rinsing), and 10% HCl in HF:H<sub>2</sub>O 1:1 (also dried without rinsing). Since atomic scale roughness variations, as well as contamination affect the gate oxide integrity, we have correlated these results with electrical parameters extracted from C-V characteristics
    Semiconductor Conference, 1998. CAS '98 Proceedings. 1998 International; 11/1998
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    ABSTRACT: This paper presents a new technological process to implement efficient millimetre-wave passive circuits on a silicon substrate. This process associates a thick positive photoresist acting as a mould for the realization of thick conductors (several microns) with an ultra-thin dielectric membrane using only two layers (SiO2/Si2N3.8) in order to reduce both dielectric and ohmic losses in the coplanar millimetre-wave circuits. Coplanar transmission lines and a band-pass filter in the 30 GHz range, featuring respectively transmission losses lower than 0.2 and 1 dB, illustrate some potentialities of this process.
    Sensors and Actuators A: Physical. 01/1998;
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    ABSTRACT: An experimental study is made to establish if the roughness of the etched surface attains a saturation value during the KOH etching of silicon, as predicted by the atomic scale simulators. We showed there is a stable saturation roughness specific to the orientation of the wafer, but much greater than the values predicted by the simulators. The same saturation roughness is reached independent on the initial roughness of the surface. Surfactants dissolved in small concentrations in the etchant were shown to reduce drastically the saturation value of the roughness and rise the etching rates, without affecting noticeable the anisotropy diagrams
    Semiconductor Conference, 1997. CAS '97 Proceedings., 1997 International; 11/1997