Abstract:
An acoustic wave device comprising at least one surface acoustic wave filter and one bulk acoustic wave filter, the device including, on a substrate comprising a second piezoelectric material: a stack of layers including a first metal layer and a layer of a first monocrystalline piezoelectric material, wherein the stack of layers is partially etched so as to define a first area in which the first and second piezoelectric materials are present and a second area in which the first piezoelectric material is absent; a second metallization at the first area for defining the bulk acoustic wave filter integrating the first piezoelectric material, and a third metallization at the second area for defining the surface acoustic wave filter integrating the second piezoelectric material.
Abstract:
An apparatus for converting vibratory mechanical energy into electrical energy includes a mobile mass, a support, first and second beams, the second being piezoelectric, and a junction element. The first beam extends longitudinally between the support and the mass, each of which has a beam end embedded therein. The second beam links the support and the mobile mass. Its elongation stiffness is lower than that of the first beam. The junction element extends between the beams. A first assembly, with a first bending stiffness, comprises the first beam, the second beam, and the junction element. A second assembly consists of the first assembly minus the second beam. Its bending stiffness is less than or equal to half of that of the first assembly.
Abstract:
An electromechanical device having a resonator using acoustic waves propagating laterally within a piezoelectric plane resonant structure and electrodes on a face of said structure. The resonant structure comprises: a transduction region having a transduction length and generating acoustic waves; a free propagation region for the acoustic waves, adjacent to the transduction region and defined the plane of the transduction region; the resonant structure length being equal to an integer number of half-wavelengths, the resonance frequency of said resonator equaling the average propagation velocity of the wave within the structure divided by said wavelength, to adjust the quality factor of the resonator fixed by the length of the resonant structure and the coupling coefficient fixed by the ratio of the transduction length over the length of the resonant structure; the resonant structure defined by the assembly of the transduction region and the propagation region being laterally bounded by reflection regions.
Abstract:
Acoustic resonator comprising an electret, and method of producing said resonator, application to switchable coupled resonator filters.The resonator comprises: at least one piezoelectric layer (30); electrodes (24, 26) on either side of this layer; and at least one electret layer (32) between the electrodes, to apply a permanent electric field to the piezoelectric layer. The intensity of this electric field is determined to shift the resonance frequency of the resonator by a desired value. The piezoelectric layer may contain electrical charges to itself constitute the electret layer.
Abstract:
In a process for fabricating a membrane, including, on a substrate, a thin-film multilayer including a film of piezoelectric material placed between a top electrode film and a bottom electrode film and an elastic film supporting said piezoelectric film, the process includes: determining at least one concavity/convexity curvature of said membrane along an axis parallel to the plane of the films so that at least one inflection point is defined, said point allowing a first region and a second region, corresponding to a concave part and a convex part or vice versa, to be isolated; depositing, on the surface of the substrate, a thin-film multilayer including at least one film of piezoelectric material, one bottom electrode film and one top electrode film; and structuring at least one of the electrode films to define at least said first membrane region, in which an electric field perpendicular to the plane of the films may be applied, and at least said second region, in which an electric field parallel to the plane of the films may be applied.
Abstract:
The invention provides a method of fabricating and electromechanical device having an active element on at least one substrate, the method having the steps of: a) making a heterogeneous substrate having a first portion, an interface layer, and a second portion, the first portion including one or more buried zones sandwiched between first and second regions formed in a first monocrystalline material, the first region extending to the surface of the first portion, and the second region extending to the interface layer, at least one said buried zone being made at least in part out of a second monocrystalline material so as to make it selectively attackable relative to the first and second regions; b) making openings from the surface of the first portion and through the first region, which openings open out to at least one said buried zone; and c) etching at least part of at least one buried zone to form at least one cavity so as to define at least one active element that is at least a portion of the second region between said cavity and said interface layer; wherein the first and second portions of the substrate are constituted respectively from first and second substrates that are assembled together by bonding, at least one of them including at least one said interface layer over at least a fraction of its surface.
Abstract:
A device for detecting elements in a fluid environment includes at least one acoustic resonator having a surface designed for fixing of elements. The resonator is configured for generating and measuring Lamb waves fostering generation of symmetrical Lamb waves. The device analyzes the resonance frequency of the resonator to determine the variation of the resonance frequency of the symmetrical Lamb waves representative of the presence of the elements.
Abstract:
A micro or nano electromechanical transducer device formed on a semiconductor substrate comprises a movable structure which is arranged to be movable in response to actuation of an actuating structure. The movable structure comprises a mechanical structure comprising at least one mechanical layer having a first thermal response characteristic and a first mechanical stress response characteristic, at least one layer of the actuating structure, the at least one layer having a second thermal response characteristic different to the first thermal response characteristic and a second mechanical stress response characteristic different to the first mechanical stress response characteristic, a first compensation layer having a third thermal response characteristic and a third mechanical stress characteristic, and a second compensation layer having a fourth thermal response characteristic and a fourth mechanical stress response characteristic. The first and second compensation layers are arranged to compensate a thermal effect produced by the different first and second thermal response characteristics of the mechanical structure and the at least one layer of the actuating structure such that movement of the movable structure is substantially independent of variations in temperature and to adjust a stress effect produced by the different first and second stress response characteristics of the mechanical structure and the at least one layer of the actuating structure such that the movable structure is deflected a predetermined amount relative to the substrate when the electromechanical transducer device is in an inactive state.
Abstract:
A device comprises at the input a first component (PA) having a first output impedance (Z1), at the output a second component (ANT) having a second input impedance (Z2), and an impedance-matching network between said first and second components. Because the first and/or the second impedance vary/varies, said impedance-matching network comprises a filter (Fadp), with an impedance that is matchable to the first and second impedances, located between said first and second components and comprising at least two acoustic wave coupled resonators. At least one of the resonators comprises a perovskite type material and means for applying a voltage to said resonator, which enable the permittivity and the impedance thereof to be varied.
Abstract:
The invention relates to a method of making a component from a heterogeneous substrate comprising first and second portions in at least one monocrystalline material, and a sacrificial layer constituted by at least one stack of at least one layer of monocrystalline Si situated between two layers of monocrystalline SiGe, the stack being disposed between said first and second portions of monocrystalline material, wherein the method consists in etching said stack by making: e) at least one opening in the first and/or second portion and the first and/or second layer of SiGe so as to reach the layer of Si; and f) eliminating all or part of the layer of Si.