Abstract: An electro-acoustic transducer includes an insulative flexible substrate, a base, and a magnetic field generator. The base includes a cavity and a magnetic portion disposed below the cavity. The insulative flexible substrate is configured to cover the cavity. The magnetic field generator can be disposed on the insulative flexible substrate and corresponds to the cavity. The magnetic field generator can produce a magnetic field and a reverse magnetic field to cause the magnetic field generator and the magnetic portion of the base to attract and repel each other, thereby vibrating the insulative flexible substrate.

Abstract: A method of manufacturing a capacitive microphone comprises providing a substrate having at least one cavity. The method further comprises forming a backplate on the substrate, wherein the backplate has a plurality of holes, and forming a diaphragm on the backplate, wherein there are a first distance and a second distance between the diaphragm and the backplate. The method still further comprises forming an air gap between the backplate and the diaphragm through the first distance, and fastening the diaphragm to the backplate through the second distance.

Abstract: An element of an ultrasonic transducer includes a first substrate, at least one cell of the ultrasonic transducer arranged above the first substrate, and a second substrate arranged under the first substrate, in which a first power supply for applying an electric signal to the first substrate is formed.

Abstract: A handheld computing device is disclosed. The handheld computing device includes a seamless housing formed from an extruded metal tube. The extruded tube includes open ends and internal rails which serve as a guide for slidably assembling an operational assembly through the open ends of the extruded tube, a reference surface for positioning the operational assembly relative to an access opening in the seamless housing, and a support structure for supporting the operational assembly during use.

Abstract: MEMS resonators containing a first material and a second material to tailor the resonator's temperature coefficient of frequency (TCF). The first material has a different Young's modulus temperature coefficient than the second material. In one embodiment, the first material has a negative Young's modulus temperature coefficient and the second material has a positive Young's modulus temperature coefficient. In one such embodiment, the first material is a semiconductor and the second material is a dielectric. In a further embodiment, the quantity and location of the second material in the resonator is tailored to meet the resonator TCF specifications for a particular application. In an embodiment, the second material is isolated to a region of the resonator proximate to a point of maximum stress within the resonator. In a particular embodiment, the resonator includes a first material with a trench containing the second material.

Abstract: An ultrasound transducer includes an array of PZT elements mounted on a non-recessed distal surface of a backing block. Between each element and the backing block is a conductive region formed as a portion of a metallic layer sputtered onto the distal surface. Traces on a longitudinally extending circuit board—preferably, a substantially rigid printed circuit board, which may be embedded within the block—connect the conductive region, and thus the PZT element, with any conventional external ultrasound imaging system. A substantially “T” or “inverted-L” shaped electrode is thereby formed for each element, with no need for soldering. At least one longitudinally extending metallic member mounted on a respective lateral surface of the backing block forms a heat sink and a common electrical ground. A thermally and electrically conductive layer, such as of foil, transfers heat from at least one matching layer mounted on the elements to the metallic member.

Abstract: A microphone assembly, in which a microphone component and an ear set component are formed on the same printed circuit board, and a method of manufacturing the microphone assembly. In the microphone assembly, one electrode of a power supplier is connected to a diaphragm assembly through a grounding pattern of the PCB and a mike cell case and the other electrode of the power supplier is supplied to a back electrode plate through a conductive member to charge two electrodes. When an acoustic signal is input to the mike cell unit, the diaphragm assembly vibrates, and thus, an electrostatic capacity of the mike cell unit changes. The acoustic signal is transmitted to a field effect transistor (FET) mounted outside the mike cell unit along a signal pattern of the PCB and is processed by the FET.

Abstract: A method of manufacturing a resonant transducer having a vibration beam includes: (a) providing an SOI substrate including: a first silicon layer; a silicon oxide layer on the first silicon layer; and a second silicon layer on the silicon oxide layer; (b) forming a first gap and second gap through the second silicon layer by etching the second silicon layer using the silicon oxide layer as an etching stop layer; (c) forming an impurity diffusion source layer on the second silicon layer; (d) forming an impurity diffused layer in a surface portion of the second silicon layer; (e) removing the impurity diffusion source layer through etching; and (f) removing at least a portion of the silicon oxide layer through etching such that an air gap is formed between the first silicon layer and a region of the second silicon layer surrounded by the first and second gaps.

Abstract: A method for fabrication of single crystal silicon micromechanical resonators using a two-wafer process, including either a Silicon-on-insulator (SOI) or insulating base and resonator wafers, wherein resonator anchors, a capacitive air gap, isolation trenches, and alignment marks are micromachined in an active layer of the base wafer; the active layer of the resonator wafer is bonded directly to the active layer of the base wafer; the handle and dielectric layers of the resonator wafer are removed; viewing windows are opened in the active layer of the resonator wafer; masking the single crystal silicon semiconductor material active layer of the resonator wafer with photoresist material; a single crystal silicon resonator is machined in the active layer of the resonator wafer using silicon dry etch micromachining technology; and the photoresist material is subsequently dry stripped.

Abstract: A method of manufacturing a boundary acoustic wave device includes the steps of forming an electrode on a first medium layer, forming a second medium layer so as to cover the electrode on the first medium layer, and forming a sound absorbing layer on an external surface of the second medium layer. The sound absorbing layer has an acoustic velocity of transverse waves that is lower than an acoustic velocity of transverse waves of the second medium layer.

Abstract: An ultrasonic transducer for use in a fluid medium. The ultrasonic transducer includes at least one housing and at least one transducer core at least partially accommodated in the housing. The transducer core includes at least one acoustic-electric transducer element. At least one damping material is also accommodated in the housing. The damping material includes at least one matrix material, at least one first filler introduced into the matrix material, and at least one second filler introduced into the matrix material. The first filler has a lower specific gravity than the matrix material. The second filler has a higher specific gravity than the matrix material.

Abstract: An electret accelerometer is provided in which a diaphragm, an electret, a back plate and an electronic circuit are placed in a casing and the casing is sealed to isolate the diaphragm from external acoustic signals.

Abstract: An electrostatic loudspeaker includes: a first electrode; a second electrode which is opposed to the first electrode; and a vibrating member which is disposed between the first electrode and the second electrode and in which an insulation membrane and a conductive membrane are stacked, the insulation membrane being disposed on both end faces of the vibrating member in a direction of the stacking.

Abstract: Provided is a method and shield for shielding a behind-the-ear hearing aid. A Mu metal shielding material is bonded to the external or internal surface of the behind-the-ear hearing aid, the shielding providing effective shielding of electromagnetic radiation in the frequency range of 0.78 Hz to 20 KHz and effective sound shielding in the audio frequency range of 20 Hz to 20,000 Hz.

Abstract: A micro-electro-mechanical microphone and manufacturing method thereof are provided in the invention. The micro-electro-mechanical microphone comprises: a diaphragm, which is formed on a surface of one side of a semiconductor substrate, exposed to the outside surroundings, and can vibrate freely by sensing the pressure generated by sound waves; an electrode plate with air holes, which is under the diaphragm; an isolation structure for fixing the diaphragm and the electrode plate; an air gap cavity between the diaphragm and the electrode plate, and a back cavity under the electrode plate and in the semiconductor substrate; a second cavity formed on the surface of the same side of the semiconductor substrate and in an open manner; the air gap cavity is connected with the back cavity through the air holes of the electrode plate; the back cavity is connected with the second cavity through an air groove formed in the semiconductor substrate.

Abstract: Earpieces and methods of forming earpieces for radio frequency (RF) mitigation are provided. An earpiece is configured to be inserted in an ear canal. The earpiece includes an insertion element and a sealing section disposed on the insertion element and configured to conform to the ear canal. The sealing section is configured to substantially mitigate radio frequency (RF) transmission and to substantially isolate the ear canal from an ambient environment.

Abstract: A movable device of acceleration sensors and a vibration device of a gyroscope are formed on the same sensor wafer spaced apart from each other by a wall. A cap wafer having gaps corresponding to the movable mechanical components of the acceleration sensors and gyroscope is provided for the wafer and an adsorbent divided into a plurality of divisional portions is disposed in the gap for the gyroscope. After the sensor wafer and the cap wafer have been bonded together at a temperature of inactivation of the adsorbent and in an atmospheric pressure ambience of noble gas and activated gas, the adsorbent divisional portions are activated in sequence to adsorb the activated gas so as to adjust the pressure inside the gyroscope, thus manufacturing a combined sensor wafer.

Abstract: A structure with an integrated circuit (IC) and a silicon condenser microphone mounted thereon includes a substrate having a first area and a second area. The IC is fabricated on the first area in order to form a conducting layer and an insulation layer. Both the conducting layer and the insulation layer further extend to the second area. The insulation layer is removed under low temperature in order to expose the conducting layer on which the silicon condenser microphone is fabricated. The silicon condenser microphone includes a first film layer, a connecting layer and a second film layer under a condition that the connecting layer connects the first and the second film layers. The first film layer and the second film layer act as two electrodes of a variable capacitance.

Abstract: A method for manufacturing a measuring apparatus for capacitive determining and/or monitoring of at least the fill level of a medium. The measuring apparatus has a probe unit and an electronics unit. During a measurement, the electronics unit supplies the probe unit with an exciter signal and receives from the probe unit a received signal, from which the electronics unit ascertains a capacitance value. The probe unit is coated with an insulation layer, the coated probe unit is connected with the electronics unit and inserted into a container containing a calibration medium, the coated probe unit is covered completely by the calibration medium and an associated received signal is gained, and, with the associated received signal, at least one adjustable component of the electronics unit is set.

Abstract: A MEMS microphone has a base, a backplate, and a backplate spring suspending the backplate from the base. The microphone also has a diaphragm forming a variable capacitor with the backplate.

Abstract: A microphone is formed to have a diaphragm that is configured to improve signal to noise ratio. To that end, the microphone has a backplate having a hole therethrough, and a diaphragm movably coupled with the backplate. The diaphragm has a bottom surface (facing the backplate) with a convex portion aligned with the hole in the backplate.

Abstract: A catheter for use in a patient's body lumen, having a shaft section configured to minimize ultrasonic image artifacts and the direct ultrasonic image brightness of the shaft surface and its internal components, and to produce its image at a wide range of imaging angles, preferably with an intensity not substantially different than surrounding tissue of the body lumen under ultrasound visualization. The shaft section is operative for the desired use of the catheter, yet is also configured to facilitate accurately imaging the shape and location of the shaft section, and easily differentiate it from the surrounding anatomy without unduly obscuring the images of the adjacent anatomy using an ultrasound imaging system.

Abstract: A method for fabricating electrostatic transducers and arrays electrically separates the substrate segments of the transducer elements from each other using a technique involving two cutting steps, in which the first step forms a patterned opening in the substrate to make a partial separation of substrate segments, and the second step completes the separation after the substrate segments have been secured to prevent instability of the substrate segments upon completion of the second step. The securing of the substrate segments may be accomplished by filling a nonconductive material in the partial separation or securing the transducer array on a support substrate. When the substrate is conductive, the separated substrate segments serve as separate bottom electrodes that can be individually addressed. The method is especially useful for fabricating ID transducer arrays.

Abstract: Method, source and seismic vibro-acoustic source element configured to generate acoustic waves under water. The seismic vibro-acoustic source element includes an enclosure having first and second openings; first and second pistons configured to close the first and second openings; an actuator system provided inside the enclosure and configured to actuate the first and second pistons to generate a wave having first frequency; and a pressure mechanism attached to the enclosure and configured to control a pressure of a fluid inside the enclosure such that a pressure of the fluid is substantially equal to an ambient pressure of the enclosure.

Abstract: A method for fabricating an acoustic sensor according to an exemplary embodiment of the present disclosure includes: forming an acoustic sensor unit by forming a lower electrode on an upper portion of a substrate, forming etching holes on the lower electrode, forming a sacrifice layer on an upper portion of the lower electrode, and coupling a diaphragm to an upper portion of the sacrifice layer; coupling a lower portion of the substrate of the acoustic sensor unit to a printed circuit board on which a sound pressure input hole is formed so as to expose the lower portion of the substrate of the acoustic sensor unit to the outside through the sound pressure input hole; attaching a cover covering the acoustic sensor unit on the printed circuit board; etching the substrate of the acoustic sensor unit to form an acoustic chamber; and removing the sacrifice layer.

Abstract: A toy apparatus having a lower base, an upper base and a doll cover for the upper base where the lower base and the upper base attach and detach with an easy twisting motion. The lower base encloses a flywheel on a shaft, and a passageway for a rack and includes a cover with an outside screw thread. The upper base is either empty or encloses three switches, a sound generator, a light source, a controller printed circuit board, and a battery chamber and includes a cover with an inside screw thread that mates with the screw thread of the lower base. The toy apparatus has two primary play modes, a first mode where the lower base, the upper base and the cover are connected and a user uses the rack to spin the flywheel.

Abstract: A process for fabricating a piezoactuated storage device having a tip array and a memory media, which includes but is not limited to: etching the regions on the surface of the silicon wafer to produce substantially pyramidal etch pits by anisotropic etching or chemical etching with potassium hydroxide (KOH); growing an oxide layer on a top surface of the silicon wafer and in the substantially pyramidal etch pits to produce oxidation sharpening of the substantially pyramidal etch pits; forming an array of conductive tips of a nanocarbon film of nanostructured carbon material by deposition, wherein the nanostructured carbon material is ultrananocrystalline diamond (UNCD), ta-C, or diamond-like carbon films; and forming an oxygen diffusion barrier layer by deposition of a TiAl, TaAl, or any other oxygen diffusion barrier layer material on the nanocarbon film.

Abstract: A method and an article of manufacture are disclosed for creating a speaker with a diaphragm of a desired size and shape by joining the frames and cones of two or more speakers together using a straight or V-shaped bridge between each adjacent pair. The compound multi-speaker makes it possible to achieve the increased diaphragm area needed for large sound systems without increasing the number of diaphragms, thus avoiding phase cancellation problems.

Abstract: This microphone unit includes a vibrating portion converting a sound to an electric signal, a substrate having a first surface where the vibrating portion is set and a second surface opposite to the first surface and including a hollow portion transmitting a sound therein, and a coating layer formed on an inner surface of the hollow portion of the substrate. The substrate further includes a first substrate sound hole portion provided on the first surface for causing the hollow portion and the vibrating portion to communicate with each other, a second substrate sound hole portion provided on the first surface for causing the hollow portion and the exterior to communicate with each other, and a coating liquid draining hole portion provided on the second surface for causing the hollow portion and the exterior to communicate with each other.

Abstract: Provided is a method for fabricating a duplexer. The method includes fabricating an embedded PCB having an isolation part built therein and forming pads on certain areas of an upper side of the embedded PCB to connect with an external terminal. Further, a first filter and a second filter are separately fabricated, each having at least one film bulk acoustic resonator which is fabricated by depositing a lower electrode, a piezoelectric layer, and an upper electrode in this respective order. Thereafter, the first and second filters are bonded onto the pads formed on the embedded PCB. The entire surface of the embedded PCD is packaged at a predetermined distance from the first and second filters.

Abstract: A method for assembling an ultrasonic surgical device includes the steps of providing a proximal end of an ultrasonic waveguide at an ultrasonic surgical handle body, removably coupling an ultrasonic-movement-generator assembly having a ultrasonic-driving-wave-signal generating circuit to the ultrasonic surgical handle body, mechanically coupling an ultrasonic transducer rotationally freely and substantially longitudinally fixedly to the ultrasonic surgical handle body to place an ultrasonic-movement-producing distal end of the ultrasonic transducer opposite and adjacent the proximal end of the ultrasonic waveguide, and rotating the waveguide and the ultrasonic transducer with respect to one another to removably fixedly couple the waveguide to the ultrasonic-movement-producing distal end of the ultrasonic transducer and to electrically couple the ultrasonic-driving-wave-signal generating circuit to the ultrasonic surgical handle body.

Abstract: An electrostatic loudspeaker comprises a membrane structure and an electrode structure. The membrane structure comprises a central membrane portion and a circumferential membrane portion. The electrode structure is configured to electrostatically interact with the membrane structure for causing a movement of the membrane structure along an axis of movement. The electrode structure comprises a circumferential electrode portion and an opening, the circumferential electrode portion being substantially aligned to the circumferential membrane portion and the opening being substantially aligned to the central membrane portion with respect to a direction parallel to the axis of movement. In an end position of the movement of the membrane structure, the central membrane portion is configured to extend at least partially through the opening. A method for operating an electrostatic loudspeaker and a method for manufacturing an electrostatic loudspeaker are also described.

Abstract: Disclosed is an auditory comprehension and audibility device that assists users in hearing and comprehending auditory signals. The auditory comprehension and audibility device includes a magnetostrictive pad and a multi-turn coil that is disposed on the magnetostrictive pad. The multi-turn coil is electrically isolated from other devices, such as a speaker. An optional permanent magnet can also be placed on the magnetostrictive pad, which may help increase audibility of said auditory signals. The auditory comprehension and audibility device can be used in mobile phone covers, head phones, hearing aids and other devices that are used for hearing.

Abstract: In one embodiment, a mobile device including a magnet unit that is thermally coupled to the heat sink portion of a housing of the mobile device is disclosed. The mobile device comprises a speaker driver that includes a magnet unit, a housing having a heat sink portion that is made of a material having a high thermal conductivity, and a thermal component. The heat sink portion has a first face that is coupled to the speaker driver and a second face that is exposed to the exterior of the mobile device. The thermal component binds the speaker driver to the first face of the heat sink portion to create a cooling path from the magnet unit to the exterior of the mobile device. Other embodiments are also described.

Abstract: An acoustic transducer and method of making the acoustic transducer is disclosed. A transducer element for converting a signal between one of an electrical signal and an acoustic signal and the other of the electrical signal and the acoustic signal is provided. A backing to the transducer is additively fabricated to a side of the transducer element. The backing includes an electrically conductive path therein for conducting the electrical signal.

Abstract: A method for manufacturing an ultrasonic transducer for use in a fluid medium is described. The ultrasonic transducer includes at least one transducer core having at least one acoustic-electric transducer element. The ultrasonic transducer furthermore includes at least one housing which at least partially surrounds the transducer core and which has at least one opening facing the fluid medium. In the method, at least one sealing film is stretched and connected to the housing in the stretched state in such a way that the sealing film at least partially seals the opening.

Abstract: Open-air earbuds and methods for making the same are disclosed. The earbud has a neck, which is open to the ambient environment in order to improve bass response. In order to prevent debris from entering the interior of the earbud, a filter is incorporated into the neck.

Abstract: According to one embodiment, an ultrasonic probe includes a plurality of piezoelectric elements, a first electrode, a plurality of second electrodes, a plurality of stacked flexible printed circuit boards, and a plurality of connection portions. The plurality of piezoelectric elements are arrayed. The first electrode is provided on the emitting surface side of the plurality of piezoelectric elements. The plurality of second electrodes are respectively provided on the rear surface sides of the plurality of piezoelectric elements. The plurality of stacked flexible printed circuit boards respectively include a plurality of terminals. The plurality of connection portions electrically connect the second electrodes to the terminals. At least one of the flexible printed circuit boards extends longer than the flexible printed circuit board serving as an upper layer.

Abstract: An electromechanical transducer includes a vibration membrane provided with a first electrode, a substrate provided with a second electrode, and a support member adapted to support the vibration membrane in such a manner that a gap is formed between the vibration membrane and the substrate, with the first and second electrodes being arranged in opposition to each other, wherein a part of the vibration membrane and a part of the substrate are in contact with each other at a contact region, and another region of the vibration membrane other than the contact region is able to vibrate; an overlap region is provided between the first electrode and second electrode in the contact region, and at least one of these electrodes has a through portion formed therethrough in at least a part of the overlap region, and a plurality of protrusions formed within the gap and on at least one of the vibration member and the support member, wherein the contact region is surrounded by the plurality of protrusions.

Abstract: An ultrasound probe includes a backing member, inorganic piezoelectric elements arranged on a top surface of the backing member, an acoustic matching layer disposed on and extending over the inorganic piezoelectric elements, and organic piezoelectric elements arranged on the acoustic matching layer.

Abstract: Seamless headsets and related systems and methods of manufacture are provided. In this regard, a representative headset includes: an earpiece assembly having a ribbon cable portion and an earpiece portion; the ribbon cable portion having a body and multiple elongated conductors, the body being formed of electrically insulating material; the earpiece portion extending from a distal end of the body, the earpiece portion being configured as a contiguous extension of the insulating material of the body such that the earpiece assembly exhibits a seamless transition from the ribbon cable portion to the earpiece portion.

Abstract: The present application provides a multilayer lateral mode coupling method for phased array construction and transducer devices built accordingly. This disclosure describes and demonstrates that the electrical impedance of a phased array can be substantially reduced and readily controlled to be close to the source impedance. The fabrication process is relatively simple and inexpensive. In addition, the elements are robust for use in 1.5, 2, 3 or other dimensional configurations, over an extended period of operation, without structural failure, and providing a high power output required for imaging and/or medical therapy applications.

Abstract: A method of adjustment on manufacturing of a monolithic oscillator including circuit elements and a BAW resonator, this method including the steps of: a) forming the circuit elements and the resonator and electrically connecting them; b) covering the resonator with a frequency adjustment layer; c) measuring the output frequency of the oscillator; d) modifying the thickness of the frequency adjustment layer to modify the output frequency of the oscillator.

Abstract: An oscillator device manufacturing method includes: placing an oscillator provided with electrodes on a convex pedestal provided on an assembly table; arranging, on the assembly table, a frame member including an opening surrounded by a frame thereof and provided with electrode pads on the frame such that the opening is positioned at the pedestal; connecting the electrode pads to the electrodes of the oscillator placed on the pedestal via wires, while the frame member is arranged on the assembly table; removing the frame member from the assembly table together with the oscillator after the connecting, and bonding the frame member connected to the oscillator to a substrate. By using the method, the oscillator device including the oscillator suspended in air above the substrate can be efficiently manufactured. In stead of using the frame member, a frame body in which frame members are arrayed can be employed.

Abstract: A surface acoustic wave device includes a surface acoustic wave element including a plurality of electrode pads, and a mount substrate. The surface acoustic wave element is flip-chip mounted on a die-attach surface of the mount substrate by bumps made of Au. The mount substrate includes at least one resin layer including via-holes, a plurality of mount electrodes provided on the die-attach surface of the mount substrate, and via-hole conductors. The mount electrodes are bonded to the electrode pads via the bumps. The via-hole conductors are provided in the via-holes. At least one of each of the electrode pads and each of the mount electrodes includes a front layer made of Au. At least one of the via-hole conductors is located below the corresponding bump.

Abstract: Embodiments provide an amplifier and a method for using and manufacturing said amplifier that incorporate an impedance matching stage, a feedback circuit, and a gain stage. The impedance matching stage is coupled to the feedback circuit wherein the feedback circuit provides a compensated operating voltage for the impedance matching stage. The output of the impedance matching stage is used to set an input bias voltage for both the impedance matching stage and the gain stage. The output of the impedance matching stage is also used, together with the output of the gain stage, to produce an output of the amplifier.

Abstract: In a method of making an ultrasonic transducer, a piezoelectric ceramic material that is at least partially covered by metal plating is provided. A plurality of substantially parallel cuts is formed in the plating so as to define a plurality of transducer elements and a ground element. A plurality of conductors is provided. An end portion of each conductor is operatively connected, such as by ultrasonic bonding, to a respective one of the transducer elements or the ground element. Next, a backing material is bonded to the plurality of transducer elements and the ground element such that the end portion of each conductor is sandwiched between the backing material and a respective one of the transducer elements or the ground element. The conductors are bent to allow for operative connection to an ultrasound system. The operative connection between the conductors and the transducer elements is maintained during the bending step.

Abstract: A method of forming a micromechanical resonator includes forming a resonator body anchored to a substrate by at least a first anchor. This resonator body may include a semiconductor or other first material having a negative temperature coefficient of elasticity (TCE). A two-dimensional array of spaced-apart trenches are provided in the resonator body. These trenches may be filled with an electrically insulating or other second material having a positive TCE. The array of trenches may extend uniformly across the resonator body, including regions in the body that have relatively high and low mechanical stress during resonance. This two-dimensional array (or network) of trenches can be modeled as a network of mass-spring systems with springs in parallel and/or in series with respect to a direction of a traveling acoustic wave within the resonator body during resonance.

Abstract: A method of manufacturing a boundary acoustic wave device includes the steps of forming an electrode on a first medium layer, forming a second medium layer so as to cover the electrode on the first medium layer, and forming a sound absorbing layer on an external surface of the second medium layer. The sound absorbing layer has an acoustic velocity of transverse waves that is lower than an acoustic velocity of transverse waves of the second medium layer.

Abstract: An ultrasonic transducer fabrication method including: depositing a conductive material on an insulating layer, partially etching the conductive material to form lower electrodes; depositing an insulating material to cover the lower electrodes to form a first insulating layer and depositing a sacrificial material thereon, performing etching, to create cavities and a channel-shaped sacrificial layer to communicate the cavities; depositing an insulating material on the first insulating layer to form a second insulating layer; partially etching the second insulating layer to form holes; etching and removing the sacrificial layer through the holes to form the cavities and channels; depositing a conductive material on the second insulating layer to plug the holes and form a conductive film; partially etching the conductive film to form upper electrodes and sealing portions which plug the holes; and forming a protective film on the second insulating layer to cover the upper electrodes and the sealing portions.