Abstract:
Method for making an electromechanical component on a plane substrate and comprising at least one structure vibrating in the plane of the substrate and actuation electrodes. The method comprises at least the following steps in sequence: formation of the substrate comprising one silicon area partly covered by two insulating areas, formation of a sacrificial silicon and germanium alloy layer by selective epitaxy starting from the uncovered part of the silicon area, formation of a strongly doped silicon layer by epitaxy, comprising a monocrystalline area arranged on said sacrificial layer and two polycrystalline areas arranged on insulating areas, simultaneous formation of the vibrating structure and actuation electrodes, by etching of a predetermined pattern in the monocrystalline area designed to form spaces between the electrodes and the vibrating structure, elimination of said sacrificial silicon and germanium alloy layer by selective etching.
Abstract:
The resonator comprises a piezoelectric layer arranged between two electrodes. An electrical heating resistor is arranged in thermal contact with at least one of the electrodes. Temporary heating of the electrode enables the material constituting the electrode to be partially evaporated, so as to thin the electrode and thus adjust the resonance frequency. Measurement of the resonance frequency in the course of evaporation enables the heating to be interrupted when the required resonance frequency is obtained. One of the electrodes can be arranged on a substrate formed by an acoustic Bragg grating. The resonator can comprise a substrate comprising a cavity whereon one of the electrodes is at least partially arranged.
Abstract:
A process for manufacturing a resonator including the steps of: forming on an insulating substrate a first portion of a conductive material and a second portion of another material on the first portion; forming an insulating layer having its upper surface flush with the upper part of the second portion; forming by a succession of depositions and etchings a beam of a conductive material above the second portion, the beam ends being on the insulating layer on either side of the second portion, the upper surface of the second portion being exposed on either side of the beam, a third portion of a piezoelectric material on the beam and a fourth portion of a conductive material on the third portion above the beam portion located above the second portion; and removing the second portion.
Abstract:
A support 7 for an acoustic resonator 4 includes at least one bilayer assembly having a layer of high acoustic impedance material 11 and a layer of low acoustic impedance material 12 made of material having a low electrical permittivity.
Abstract:
The resonator comprises a piezoelectric layer arranged between two electrodes. An electrical heating resistor is arranged in thermal contact with at least one of the electrodes. Temporary heating of the electrode enables the material constituting the electrode to be partially evaporated, so as to thin the electrode and thus adjust the resonance frequency. Measurement of the resonance frequency in the course of evaporation enables the heating to be interrupted when the required resonance frequency is obtained. One of the electrodes can be arranged on a substrate formed by an acoustic Bragg grating. The resonator can comprise a substrate comprising a cavity whereon one of the electrodes is at least partially arranged.
Abstract:
A process is disclosed to detect a water condensation risk on a surface in contact with a wet air volume, which uses the steps of (a) placing a sensitive element on the surface, which initially takes a temperature corresponding to that of the surface, (b) by means of a heating device on this sensitive element, initiating a first heating phase until a temperature higher than the surface temperature is reached, (c) by means of a cooling device having the same thermal power as the heating device, initiating a cooling phase until a temperature lower than the surface temperature is provoked on the sensitive element, and (d) a comparison is made between the ratio of the first heating phase time to the temperature rise during heating and the ratio of cooling phase time to the temperature decrease during the cooling, a noticeable difference between these two ratios indicating a significant risk of condensation on the surface.
Abstract:
A Peltier effect device which detects in particular a condensation risk, includes a substrate and semiconducting bands disposed on the upper face of the substrate. The junctions connecting said bands which make up a series circuit are formed by semiconducting bands of N-type and P-type. Junctions of the same type, i.e., N-P type are situated on the central zone of the upper face of the substrate and defines a detection zone of the device. Semiconducting bands of one type are placed on one side of the upper face of the substrate and bands of the other type are placed on the other side of the upper face of the substrate. The substrate also includes at the peripheral zone of each band, except for a frontmost N-type band and a rearmost P-type band, a plated hole extending through the substrate to a lower face of the substrate and to a plating of the lower face such that a plated hole situated at an end of the P-type band is connected to a plated hole situated at an end of a next N-type band.