Abstract: The pressure sensor according to the present invention has a sensor chip having a first semiconductor layer that has an opening portion, and a second semiconductor layer, formed on the first semiconductor layer, having a recessed portion that forms a diaphragm and a base, having a pressure guiding hole that is connected to the opening portion, bonded to the sensor chip. The recessed portion in the second semiconductor layer is larger than the opening portion of the first semiconductor layer. The opening portion of the first semiconductor layer has an opening diameter on the second semiconductor layer side that is larger than the opening diameter on the base side.

Abstract: The present invention relates to a CMOS compatible MEMS microphone, comprising: an SOI substrate, wherein a CMOS circuitry is accommodated on its silicon device layer; a microphone diaphragm formed with a part of the silicon device layer, wherein the microphone diaphragm is doped to become conductive; a microphone backplate including CMOS passivation layers with a metal layer sandwiched and a plurality of through holes, provided above the silicon device layer, wherein the plurality of through holes are formed in the portions thereof opposite to the microphone diaphragm, and the metal layer forms an electrode plate of the backplate; a plurality of dimples protruding from the lower surface of the microphone backplate opposite to the diaphragm; and an air gap, provided between the diaphragm and the microphone backplate, wherein a spacer forming a boundary of the air gap is provided outside of the diaphragm or on the edge of the diaphragm; wherein a back hole is formed to be open in substrate underneath the diaph

Abstract: A method of manufacturing a microphone using epitaxially grown silicon. A monolithic wafer structure is provided. A wafer surface of the structure includes poly-crystalline silicon in a first horizontal region and mono-crystalline silicon in a second horizontal region surrounding a perimeter of the first horizontal region. A hybrid silicon layer is epitaxially deposited on the wafer surface. Portions of the hybrid silicon layer that contact the poly-crystalline silicon use the poly-crystalline silicon as a seed material and portions that contact the mono-crystalline silicon use the mono-crystalline silicon as a seed material. As such, the hybrid silicon layer includes both mono-crystalline silicon and poly-crystalline silicon in the same layer of the same wafer structure. A CMOS/membrane layer is then deposited on top of the hybrid silicon layer.

Abstract: A micro-electro-mechanical system (MEMS) pressure sensor includes a silicon spacer defining an opening, a silicon membrane layer mounted above the spacer, a silicon sensor layer mounted above the silicon membrane layer, and a capacitance sensing circuit. The silicon membrane layer forms a diaphragm opposite of the spacer opening, and a stationary perimeter around the diaphragm and opposite the spacer. The silicon sensor layer includes an electrode located above the diaphragm of the silicon membrane layer. The capacitance sensing circuit is coupled to the electrode and the silicon membrane layer. The electrode and the silicon membrane layer move in response to a pressure applied to the diaphragm. The movement of the silicon membrane layer causes it to deform, thereby changing the capacitance between the electrode and the silicon membrane layer by an amount proportional to the change in the pressure.

Abstract: A method manufactures an electronic device comprising a MEMS device overmolded in a protective casing. The MEMS device includes an active surface wherein a portion of the MEMS device is integrated, and is sensitive, through a membrane, to chemical/physical variations of a fluid. Prior to the molding step, at least one resin layer is formed on at least one region overlying the active surface in correspondence with the membrane. After, at least one portion of at least one resin layer is removed from at least one region, so that in the region an opening is formed, through which the MEMS device is activated from the outside of the protective casing.

Abstract: A plurality of Fabry-Perot interferometric sensors are optically coupled in series with each other to form an ordered optical series. Each Fabry-Perot interferometric sensor has a unique signalband and a passband. Each Fabry-Perot interferometric sensor has its unique signalband within the passbands of all of the next higher ordered Fabry-Perot interferometric sensors in the optical series so that a corresponding unique fringe signal from each of the Fabry-Perot interferometric sensors is a multiplexed output from the optical series.

Abstract: An electronic MEMS device is formed by a chip having with a main face and bonded to a support via an adhesive layer. A cavity extends inside the chip from its main face and is closed by a flexible film covering the main face of the chip at least in the area of the cavity. The support has a depressed portion facing the cavity and delimited by a protruding portion facing the main face of the chip. Inside the depressed portion, the adhesive layer has a greater thickness than the projecting portion so as to be able to absorb any swelling of the flexible film as a result of the expansion of the gas contained inside the cavity during thermal processes.

Abstract: A method of forming a microphone forms a backplate, and a flexible diaphragm on at least a portion of a wet etch removable sacrificial layer. The method adds a wet etch resistant material, where a portion of the wet etch resistant material is positioned between the diaphragm and the backplate to support the diaphragm. Some of the wet etch resistant material is not positioned between the diaphragm and backplate. The method then removes the sacrificial material before removing any of the wet etch resistant material added during the prior noted act of adding. The wet etch resistant material then is removed substantially in its entirety after removing at least part of the sacrificial material.

Abstract: A bulk GaN layer is on a first surface of a substrate, wherein the bulk GaN layer has a GaN transistor region and a bulk acoustic wave (BAW) device region. A source/drain layer is over a first surface of the bulk GaN layer in the GaN transistor region. A gate electrode is formed over the source/drain layer. A first BAW electrode is formed over the first surface of the bulk GaN layer in the BAW device region. An opening is formed in a second surface of the substrate, opposite the first surface of the substrate, which extends through the substrate and exposes a second surface of the bulk GaN layer, opposite the first surface of the bulk GaN layer. A second BAW electrode is formed within the opening over the second surface of the bulk GaN layer.

Abstract: Disclosed herein is an inertial sensor, which includes a diaphragm having a piezoelectric element or a piezoresistive element formed on one surface thereof, a mass element integrated with the center of the other surface of the diaphragm in which the distal end of the mass element has a larger width than the width of the proximal end in contact with the diaphragm, and a supporter formed along the edge of the other surface of the diaphragm, so that the use of the mass element having the above shape results in decreased spring constant and increased distance from the center of the diaphragm to the center of the mass element, thereby simultaneously realizing a reduction in the size of the inertial sensor and an increase in performance thereof. A method of manufacturing the inertial sensor is also provided.

Abstract: A method for manufacturing a MEMS device, includes: preparing a substrate provided with a first substrate in which a cavity is formed, and a second substrate that is bonded to a side of the first substrate on which the cavity is formed and includes a slit to delimit a movable portion in a position corresponding to the cavity, the second substrate, including a first surface thereof facing the first substrate, being provided with a thermally-oxidized film selectively formed on the first surface in a position corresponding to the movable portion; forming a first electrode layer on a second surface opposite to the first surface on which the thermally-oxidized film for the movable portion is formed; forming a sacrifice layer on the first electrode layer and the second substrate; forming a second electrode layer on the sacrifice layer; and removing the sacrifice layer and the thermally-oxidized film after the second electrode layer is formed.

Abstract: This invention provides a technique whereby, even if a step is produced by splitting a lower electrode into component elements, resistance increase of an upper electrode, damage to a membrane and decrease of dielectric strength between an upper electrode and the lower electrode, are reduced. In an ultrasonic transducer comprising plural lower electrodes, an insulation film covering the lower electrodes, plural hollow parts formed to overlap the lower electrodes on the insulation film, an insulation film filling the gaps among the hollow parts, an insulation film covering the hollow parts and insulation film, plural upper electrodes formed to overlap the hollow parts on the insulation film and plural interconnections joining them, the surfaces of the hollow parts and insulation film are flattened to the same height.

Abstract: A method of modifying stress characteristics of a membrane in one embodiment includes providing a membrane layer, determining a desired stress modification, and forming at least one trough in the membrane layer based upon the determined desired stress modification.

Abstract: A method for manufacturing a micromechanical sound transducer includes depositing successive layers of first and second membrane support material on a first main surface of a substrate arrangement with a first etching rate and a lower second etching rate, respectively. A layer of membrane material is then deposited. A cavity is created in the substrate arrangement from a side of the substrate arrangement opposite to the membrane support materials and the membrane material at least until the cavity extends to the layer of first membrane support material. The layers of first and second membrane support material are etched by applying an etching agent through the cavity in at least one first region located in an extension of the cavity also in a second region surrounding the first region. The etching creates a tapered surface on the layer of second membrane support material in the second region.

Abstract: Low temperature, multi-layered, planar microshells for encapsulation of devices such as MEMS and microelectronics. The microshells include a planar perforated pre-sealing layer, below which a non-planar sacrificial layer is accessed, and a sealing layer to close the perforation in the pre-sealing layer after the sacrificial material is removed. In an embodiment, the pre-sealing layer has perforations formed with a damascene process to be self-aligned to the chamber below the microshell. The sealing layer may include a nonhermetic layer to physically occlude the perforation and a hermetic layer over the nonhermetic occluding layer to seal the perforation. In a particular embodiment, the hermetic layer is a metal which is electrically coupled to a conductive layer adjacent to the microshell to electrically ground the microshell.

Abstract: Disclosed herein is a microelectromechanical device and a process for manufacturing same. One or more embodiments may include forming a semiconductor structural layer separated from a substrate by a dielectric layer, and opening a plurality of trenches through the structural layer exposing a portion of the dielectric layer. A sacrificial portion of the dielectric layer is selectively removed through the plurality of trenches in membrane regions so as to free a corresponding portion of the structural layer to form a membrane. To close the trenches, the wafer is brought to an annealing temperature for a time interval in such a way as to cause migration of the atoms of the membrane so as to reach a minimum energy configuration.

Abstract: A method for manufacturing a micromachine is provided which can remove a sacrifice layer and can perform sealing without using a specific packaging technique. In a method for manufacturing a micromachine (1) including an oscillator (4), a step of forming a sacrifice layer around a movable portion of the oscillator (4); a step of covering a sacrifice layer with an overcoat film (8), followed by the formation of a penetrating hole (10) reaching the sacrifice layer in the overcoat layer (8); a step of performing sacrifice-layer etching for removing the sacrifice layer using the penetrating hole (10) in order to form a space around the movable portion; and a step of performing a film-formation treatment at a reduced pressure following the sacrifice-layer etching so as to seal the penetrating hole (10).

Abstract: Provided is a high-sensitivity MEMS-type z-axis vibration sensor, which may sense z-axis vibration by differentially shifting an electric capacitance between a doped upper silicon layer and an upper electrode from positive to negative or vice versa when center mass of a doped polysilicon layer is moved due to z-axis vibration. Particularly, since a part of the doped upper silicon layer is additionally connected to the center mass of the doped polysilicon layer, and thus an error made by the center mass of the doped polysilicon layer is minimized, it may sensitively respond to weak vibration of low frequency such as seismic waves. Accordingly, since the high-sensitivity MEMS-type z-axis vibration sensor sensitively responds to a small amount of vibration in a low frequency band, it can be applied to a seismograph sensing seismic waves of low frequency which have a very small amount of vibration and a low vibration speed.

Abstract: The present invention provides a MEMS device, be implemented on many MEMS device, such as MEMS microphone, MEMS speaker, MEMS accelerometer, MEMS gyroscope. The MEMS device includes a substrate. A dielectric structural layer is disposed over the substrate, wherein the dielectric structural layer has an opening to expose the substrate. A diaphragm layer is disposed over the dielectric structural layer, wherein the diaphragm layer covers the opening of the dielectric structural layer to form a chamber. A conductive electrode structure is adapted in the diaphragm layer and the substrate to store nonvolatile charges.

Abstract: A piezoelectric device includes a piezoelectric thin film formed by separating and forming a piezoelectric single crystal substrate, an inorganic layer formed on a back surface of the piezoelectric thin film, an elastic body layer disposed on a surface opposite to the piezoelectric thin film of the inorganic layer, and a support pasted to a surface opposite to the inorganic layer of the elastic body layer. In a membrane structure portion, the inorganic layer and the elastic body layer are disposed on the piezoelectric thin film through a gap layer. The elastic body layer reduces a stress caused by pasting the piezoelectric thin film including the inorganic layer and the support and has a certain elastic modulus. The inorganic layer is formed with a material having an elastic modulus higher than that of the elastic body layer and suppresses damping caused by disposing the elastic body layer.

Abstract: A piezo speaker pressure sensor that includes a bladder and a piezo speaker element. The bladder abuts the piezo speaker element. A pressure may be sensed from the piezo speaker element proportional to a pressure exerted on the bladder in a direction of the piezo speaker element. The piezo speaker element functions as a speaker when audio signals are received by the piezo speaker element.

Abstract: An efficient deposition process is provided for fabricating reliable RF MEMS capacitive switches with multilayer ultrananocrystalline (UNCD) films for more rapid recovery, charging and discharging that is effective for more than a billion cycles of operation. Significantly, the deposition process is compatible for integration with CMOS electronics and thereby can provide monolithically integrated RF MEMS capacitive switches for use with CMOS electronic devices, such as for insertion into phase array antennas for radars and other RF communication systems.

Abstract: A manufacturing method for a micromechanical component, a corresponding composite component, and a corresponding micromechanical component are described.

Abstract: Provided is a method of manufacturing a capacitive electromechanical transducer, including: forming a lower electrode layer on a substrate; forming a sacrificial layer on the lower electrode layer; forming by application a resist layer on the sacrificial layer to form a cavity pattern; forming an insulating layer above regions including a region that contains the resist layer used to form the cavity pattern, and then removing a part of the insulating layer that is formed above the resist layer along with the resist layer, thereby leaving the insulating layer in the other regions than the region where the cavity pattern has been formed; forming a vibrating film above the region where the cavity pattern has been formed and the regions where the insulating layer remains; and removing the sacrificial layer to form a cavity.

Abstract: A capacitance type pressure sensor includes a semiconductor substrate having a reference pressure compartment formed therein, a diaphragm formed of a portion of the semiconductor substrate and formed in a surface layer portion of the semiconductor substrate to define the reference pressure compartment, the diaphragm having a through-hole communicating with the reference pressure compartment, fillers arranged within the through-hole, and an isolation insulating layer surrounding the diaphragm to isolate the diaphragm from the remaining portion of the semiconductor substrate.

Abstract: The present invention relates to integrating an inertial mechanical device on top of a CMOS substrate monolithically using IC-foundry compatible processes. The CMOS substrate is completed first using standard IC processes. A thick silicon layer is added on top of the CMOS. A subsequent patterning step defines a mechanical structure for inertial sensing. Finally, the mechanical device is encapsulated by a thick insulating layer at the wafer level. Comparing to the incumbent bulk or surface micromachined MEMS inertial sensors, the vertically monolithically integrated inertial sensors have smaller chip size, lower parasitics, higher sensitivity, lower power, and lower cost.

Abstract: Embodiments of embedded MEMS sensors and related methods are described herein. Other embodiments and related methods are also disclosed herein.

Abstract: Embodiments of displays with embedded MEMS sensors and related methods are described herein. Other embodiments and related methods are also disclosed herein.

Abstract: Embodiments are directed to the formation of multi-layer three-dimensional structures by forming and attaching a plurality of layers where each of the plurality of layers comprises at least one structural material forming a pattern and where at least one of the plurality of layers comprises at least one sacrificial material. In one embodiment, the formation of a multi-layer three-dimensional structure comprises (1) forming a plurality of individual layers and (2) attaching at least the formed plurality of individual layers together. In another embodiment, the formation of a multi-layer three-dimensional structure comprises (1) attaching an individual layer onto a substrate or onto a previously formed layer; (2) processing the attached individual layer to form a new layer comprising at least one material forming a pattern; and (3) repeating the steps of (1) and (2) one or more times.

Abstract: A method for manufacturing a micromechanical component and the micromechanical component produced thereby. This component is preferably a diaphragm or a diaphragm layer which is independently produced for the purpose of subsequent assembly with other components.

Abstract: Embodiments show a method for fabricating a cavity structure, a semiconductor structure, a cavity structure for a semiconductor device and a semiconductor microphone fabricated by the same. In some embodiments the method for fabricating a cavity structure comprises providing a first layer, depositing a carbon layer on the first layer, covering at least partially the carbon layer with a second layer to define the cavity structure, removing by means of dry etching the carbon layer between the first and second layer so that the cavity structure is formed.

Abstract: A solar device is provided, comprising a substrate structure having a surface region, a flexible and conformal material comprising a polymer material affixing the surface region, and one or more solar cells spatially provided by one or more films of materials characterized by a thickness dimension of 25 microns and less and mechanically coupled to the flexible and conformal material. The one or more solar cells have a flexible characteristic. The flexible characteristic maintains each of the solar cells substantially free from any damage or breakage thereto when the one or more films of materials is subjected to bending.

Abstract: In a method of manufacturing a semiconductor pressure sensor, a multilayer structure including a polysilicon diaphragm, a polysilicon gauge resistor formed on a side of a space which is to serve as a vacuum chamber below the polysilicon diaphragm, and a group of insulating films containing the polysilicon diaphragm and the polysilicon gauge resistor and having an etching solution introduction hole in contact with a sacrificial layer is formed on the sacrificial layer. Then, an etching solution is supplied through the etching solution introduction hole and the sacrificial layer is etched with the etching solution, to thereby obtain a diaphragm body formed of the multilayer structure, which functions on the vacuum chamber, and a surface of a silicon substrate below a first opening of a first insulating film is etched to thereby form the space which is to serve as the vacuum chamber and a diaphragm stopper disposed in the space, protruding toward near the center of the diaphragm body.

Abstract: A microphone package structure is provided, including an integrated circuit (IC) structure and a microphone structure disposed thereover and electrically connected therewith. The IC structure includes a first semiconductor substrate with opposite first and second surfaces, and a first through hole disposed in and through the first semiconductor substrate. The microphone structure includes: a second semiconductor substrate with opposite third and fourth surfaces, wherein the third surface faces to the second surface of the first semiconductor substrate; a second through hole disposed in and through the second semiconductor substrate; an acoustic sensing device embedded in the second through hole and adjacent to the third surface; and a sealing layer disposed over the fourth surface of the second semiconductor substrate, defining a back chamber with the sealing layer, wherein the first through hole allows acoustic pressure waves to penetrate and pass therethrough to the acoustic sensing device.

Abstract: A microphone arrangement comprises a stack arrangement (1) which comprises a first semiconductor body (10) having a microphone structure (13) and a second semiconductor body (80). The second semiconductor body (80) comprises a first main face (81) on which an integrated circuit (83) is arranged and a second main face (82) which faces the first semiconductor body (10).

Abstract: A device includes a first device structure having a semiconductor platform, and a second device structure having a microstructure spaced from the semiconductor platform. The device further includes a cable having a plurality of beams to couple the microstructure to the first device structure. Each beam of the plurality of beams has a polymer coating and a serpentine-shaped region.

Abstract: A method for producing oblique surfaces in a substrate, comprising a formation of recesses on both surfaces of the substrate, until the recesses are so deep that the substrate is perforated by the two recesses. One recess is produced going out from a first main surface in the region of a first surface, and the other recess is produced going out from the second main surface in the region of a second surface, so that the first surface and the second surface do not coincide along a surface normal of the main surfaces of the substrate. Subsequently, flexible diaphragms are attached over the recesses on each of the main surfaces. If a vacuum pressure is then produced inside the recesses, the flexible diaphragms each curve in the direction of the recesses until their surfaces facing the substrate come into contact with one another, generally in the center of the recesses.

Abstract: A capacitive sensor is configured for collapsed mode, e.g. for measuring sound or pressure, wherein the moveable element is partitioned into smaller sections. The capacitive sensor provides increased signal to noise ratio.

Abstract: In a method for manufacturing a micromechanical membrane structure, a doped area is created in the front side of a silicon substrate, the depth of which doped area corresponds to the intended membrane thickness, and the lateral extent of which doped area covers at least the intended membrane surface area. In addition, in a DRIE (deep reactive ion etching) process applied to the back side of the silicon substrate, a cavity is created beneath the doped area, which DRIE process is aborted before the cavity reaches the doped area. The cavity is then deepened in a KOH etching process in which the doped substrate area functions as an etch stop, so that the doped substrate area remains as a basic membrane over the cavity.

Abstract: A method for producing a device including at least one integrated circuit and at least one N/MEMS. The method produces the N/MEMS in at least one upper layer arranged at least above a first section of a substrate, produces the integrated circuit in a second section of the substrate and/or in a semiconductor layer arranged at least above the second section of the substrate, and further produces a cover encapsulating the N/MEMS from at least one layer used for production of a gate in the integrated circuit and/or for producing at least one electrical contact of the integrated circuit.

Abstract: A method for fabricating MEMS device includes providing a substrate having a first side and a second side. Then, a structural dielectric layer is formed over the substrate at the first side, wherein a structural conductive layer is embedded in the structural dielectric layer. A multi-stage patterning process is performed on the substrate from the second side, wherein a plurality of regions of the substrate with different levels is formed and a portion of the structural dielectric layer is exposed. An isotropic etching process is performed from the second side of the substrate or from the both side of the substrate to etch the structural dielectric layer, wherein a remaining portion of the structural dielectric layer comprises the structural conductive layer and a dielectric portion enclosed by the structural conductive layer.

Abstract: A semiconductor sensor of which the thickness may be reduced and a method of manufacturing a sensor body for the semiconductor sensor are provided. A total length L1 of a weight portion 5 and an additional weight portion 3 as measured in an extending direction of a centerline C is determined to be shorter than a length L2 of a support portion 7 as measured in the extending direction of the centerline C. The weight portion 5 and the additional weight portion 3 are received within a space 15 defined, being surrounded by the support portion 7. Then, dimensions and shapes of the weight portion 5 and the additional weight portion 3 are determined to allow the weight portion 5 and the additional weight portion 3 to move within the space 15.

Abstract: Method for manufacturing a semiconductor pressure sensor, wherein, in a silicon substrate, trenches are dug and delimit walls; a closing layer is epitaxially grown, that closes the trenches at the top and forms a suspended membrane; a heat treatment is performed so as to cause migration of the silicon of the walls and to form a closed cavity underneath the suspended membrane; and structures are formed for transducing the deflection of the suspended membrane into electrical signals.

Abstract: A micromechanical component having at least two caverns is provided, the caverns being delimited by the micromechanical component and a cap, and the caverns having different internal atmospheric pressures. The micromechanical component and cap are hermetically joined to one another at a first specifiable atmospheric pressure, then an access to at least one cavern is produced, and subsequently the access is hermetically closed off at a second specifiable atmospheric pressure.

Abstract: In a manufacturing method of a semiconductor device, a substrate including single crystalline silicon is prepared, a reformed layer that continuously extends is formed in the substrate, and the reformed layer is removed by etching. The forming the reformed layer includes polycrystallizing a portion of the single crystalline silicon by irradiating the substrate with a pulsed laser beam while moving a focal point of the laser beam in the substrate.

Abstract: A method for etching a diaphragm pressure sensor based on a hybrid anisotropic etching process. A substrate with an epitaxial etch stop layer can be etched utilizing an etching process in order to form a diaphragm at a selective portion of the substrate. The diaphragm can be oriented at an angle (e.g., 45 degree) with respect to the substrate in order to avoid an uncertain beveled portion in a stress/strain field of the diaphragm. The diaphragm can be further etched utilizing an etch finishing process to create an anisotropic edge portion on the major areas of the diaphragm and optimize the thickness and size of the diaphragm. Such an approach provides an enhanced diaphragm structure with respect to a wide range of pressure sensor applications.

Abstract: A method of forming a microphone having a variable capacitance first deposits high temperature deposition material on a die. The high temperature material ultimately forms structure that contributes to the variable capacitance. The method then forms circuitry on the die after depositing the deposition material. The circuitry is configured to detect the variable capacitance.

Abstract: Provided is an acoustic sensor. The acoustic sensor includes: a substrate including sidewall portions and a bottom portion extending from a bottom of the sidewall portions; a lower electrode fixed at the substrate and including a concave portion and a convex portion, the concave portion including a first hole on a middle region of the bottom, the convex portion including a second hole on an edge region of the bottom; diaphragms facing the concave portion of the lower electrode, with a vibration space therebetween; diaphragm supporters provided on the lower electrode at a side of the diaphragm and having a top surface having the same height as the diaphragm; and an acoustic chamber provided in a space between the bottom portion and the sidewall portions below the lower electrode.

Abstract: A cost-effective technology for implementing a micromechanical component is provided, whose layer construction includes at least one diaphragm on the upper side and at least one counter-element, a hollow space being formed between the diaphragm and the counter-element, and the counter-element having at least one through hole to a back volume. This back volume is formed by a sealed additional hollow space underneath the counter-element and is connected to the upper-side of the layer construction by at least one pressure equalization opening. This component structure permits the integration of the micromechanical sensor functions and evaluation electronics on one chip and is additionally suitable for mass production.

Abstract: A method for producing a device with at least one suspended membrane, including the following steps: Producing a trench through a first sacrificial layer and a second layer deposited on the first sacrificial layer, the trench completely surrounding at least a portion of the first sacrificial layer and at least a portion of the second layer, filling all or a portion of the trench with at least one material capable of resisting at least one etching agent, and etching the portion of the first sacrificial layer with the etching agent through at least one opening made in the second layer, the portion of the second layer forming at least one portion of the suspended membrane.