Abstract: A monolithic micro or nano electromechanical transducer device includes a pair of substrates (20, 25) respectively mounting one or more elongate electrical conductors (40) and resilient solid state hinge means (30, 32) integral with and linking the substrates to relatively locate the substrates so that respective elongate electrical conductors (40) of the substrates are opposed at a spacing that permits a detectable quantum tunnelling current between the conductors when a suitable electrical potential difference is applied across the conductors. The solid state hinge means permits relative parallel translation of the substrates transverse to the elongate electrical conductors.

Abstract: Provided are a Micro Electro-Mechanical System (MEMS) package and a method of packaging the MEMS package. The MEMS package includes: a MEMS device including MEMS structures formed on a substrate, first pad electrodes driving the MEMS structures, first sealing parts formed at an edge of the substrate, and connectors formed on the first pad electrodes and the first sealing parts; and a MEMS driving electronic device including second pad electrodes and second sealing parts respectively corresponding to the first pad electrodes and the first sealing parts to be sealed with and bonded to the MEMS device through the connectors to form an air gap having a predetermined width.

Abstract: A fabricating method of integrated circuit is provided. During the fabricating process of an interconnecting structure of the integrated circuit, a micro electromechanical system (MENS) diaphragm is formed between two adjacent dielectric layers of the interconnecting structure. The method of forming the MENS diaphragm includes the following steps. Firstly, a plurality of first openings is formed within any dielectric layer to expose corresponding conductive materials of the interconnecting structure. Secondly, a bottom insulating layer is formed on the dielectric layer and filling into the first openings. Third, portions of the bottom insulating layer located in the first openings are removed to form at least a first trench for exposing the corresponding conductive materials. Then, a first electrode layer and a top insulating layer are sequentially formed on the bottom insulating layer, and the first electrode layer filled into the first trench and is electrically connected to the conductive materials.

Abstract: A method of manufacturing an MEMS device includes: forming a covering structure having an MEMS structure and a hollow portion, which is located on a periphery of the MEMS structure and is opened to an outside, on a substrate; and performing surface etching for the MEMS structure in a gas phase by supplying an etching gas to the periphery of the MEMS structure from the outside.

Abstract: A method produces electronic components in particular electronic sensors for pressure and differential pressure measurement. Firstly, the semiconductor structure of the electronic components is produced on a wafer. An insulating oxide layer is then applied. A protective metal layer is subsequently applied. The metal layer is applied in sections only in those regions of the wafer in which no splitting, for example by mechanical separation, occurs later. The electronic components thus formed in the wafer are then divided up into individual elements.

Abstract: A micro-electro-mechanical transducer (such as a cMUT) is disclosed. The transducer has a base, a spring layer placed over the base, and a mass layer connected to the spring layer through a spring-mass connector. The base includes a first electrode. The spring layer or the mass layer includes a second electrode. The base and the spring layer form a gap therebetween and are connected through a spring anchor. The mass layer provides a substantially independent spring mass contribution to the spring model without affecting the equivalent spring constant. The mass layer also functions as a surface plate interfacing with the medium to improve transducing performance. Fabrication methods to make the same are also disclosed.

Abstract: An embodiment of a method is provided that includes providing a substrate having a frontside and a backside. A CMOS device is formed on the substrate. A MEMS device is also formed on the substrate. Forming the MEMS device includes forming a MEMS mechanical structure on the frontside of the substrate. The MEMS mechanical structure is then released. A protective layer is formed on the frontside of the substrate. The protective layer is disposed on the released MEMS mechanical structure (e.g., protects the MEMS structure). The backside of the substrate is processed while the protective layer is disposed on the MEMS mechanical structure.

Abstract: An integrated differential pressure sensor includes, in a monolithic body of semiconductor material, a first face and a second face, a cavity extending at a distance from the first face and delimited therewith by a flexible membrane formed in part by epitaxial material from the monolithic body and in part by annealed epitaxial material from the monolithic body, an access passage in fluid communication with the cavity, and in the flexible membrane at least one transduction element configured so as to convert a deformation of the flexible membrane into electrical signals. The cavity is formed in a position set at a distance from the second face and is delimited at the second face with a portion of the monolithic body.

Abstract: A method for fabricating a micro-electro-mechanical device (such as a cMUT) is disclosed. The method combines a substrate, a middle spring layer and a top plate using wafer bonding technology or sacrificial technology. A cavity is formed on either the top of the substrate or the bottom of the middle spring layer. A connector is formed on either the top of the middle spring layer or the bottom of the top plate. Upon joining the three layers, the connector defines a transducing space between the top plate and the middle spring layer. The connector is horizontally distanced from the sidewall to define a cantilever anchored at the sidewall. The cantilever and the cavity allow a vertical displacement of the connector, which transports the top wafer in a piston-like motion to change the transducing space. Multiple device elements can be made on the same substrate.

Abstract: According to the present invention, a micro-electro-mechanical system (MEMS) device comprises: a thin film structure including at least a metal layer and a protection layer deposited in any order; and a protrusion connected under the thin film structure. A preferred thin film structure includes at least a lower protection layer, a metal layer and an upper protection layer. The MEMS device for example is a capacitive MEMS acoustical sensor.

Abstract: This patent discloses an integrated electronic and optical MEMS (micro-electro-mechanical systems) based sensor wherein the same embossed diaphragm is used as the sensing element of both integrated parts. The optical part of the sensor is based on a Fabry-Perot cavity and the electronic part of the sensor is based on the piezoresistive effect. The signal output obtained from the electronic part of the sensor will be used to assist the fabrication of the Fabry-Perot cavities and as a reference to establish the quiescence point (Q-point) of the signal output from the optical part of the sensor. The invention includes sensors for detecting mechanical movements, such as those caused by pressure, sound, magnetic fields, temperature, chemical reaction or biological activities.

Abstract: In a method for manufacturing a micromechanical component, a cavity is produced in the substrate from an opening at the rear of a monocrystalline semiconductor substrate. The etching process used for this purpose and the monocrystalline semiconductor substrate used are controlled in such a way that a largely rectangular cavity is formed.

Abstract: A method for fabricating a sensor is disclosed that in one embodiment bonds a first device wafer to an etched second device wafer to create a suspended structure, the flexure of which is determined by an embedded sensing element that is in electrical communication with an outer surface of the sensor through an interconnect embedded in a device layer of the first device wafer. In one embodiment the suspended structure is enclosed by a cap and the sensor is configured to measure absolute pressure.

Abstract: A method for manufacturing a MEMS sensor and a thin film thereof includes steps of etching a top surface of a single-crystal silicon wafer in combination of a deposition process, an isotropic DRIE process, a wet etching process and a back etching process in order to form a pressure-sensitive single-crystal silicon film, a cantilever beam, a mass block, a front chamber, a back chamber and trenches connecting the front and the back chambers. The single-crystal silicon film is prevented from etching so that the thickness thereof can be well controlled. The method of the present invention can be used to replace the traditional method which forms the back chamber and the pressure-sensitive single-crystal silicon film from the bottom surface of the silicon wafer.

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.

Abstract: A method of fabricating a MEMS microphone includes: first providing a substrate having a first surface and a second surface. The substrate is divided into a logic region and a MEMS region. The first surface of the substrate is etched to form a plurality of first trenches in the MEMS region. An STI material is then formed in the plurality of first trenches. Subsequently, the second surface of the substrate is etched to form a second trench in the MEMS region, wherein the second trench connects with each of the first trenches. Finally, the STI material in the first trenches is removed.

Abstract: A method of forming Monolithic CMOS-MEMS hybrid integrated, packaged structures includes the steps of providing: providing at least one semiconductor substrate having a CMOS device area including dielectric layers and metallization layers; applying at least one protective layer overlying the CMOS device area; forming at least one opening on the protective layer and patterning the dielectric and metallization layers to access the semiconductor substrate; forming at least one opening on the semiconductor substrate by etching the dielectric and metallization layers; applying at least one filler layer in the at least one opening on the semiconductor substrate; positioning at least one chip on the filler layer, the chip including a prefabricated front face and a bare backside; applying a first insulating layer covering the front face of the chip providing continuity from the semiconductor substrate to the chip; forming at least one via opening on the insulating layer covering the chip to access at least one contac

Abstract: A method for fabricating MEMS device includes: providing a single crystal substrate, having first surface and second surface and having a MEMS region and an IC region; forming SCS mass blocks on the first surface in the MEMS region; forming a structural dielectric layer over the first surface of the substrate, wherein a dielectric member of the structural dielectric layer is filled in spaces surrounding the SCS mass blocks in the MEMS region, the IC region has a circuit structure with an interconnection structure formed in the structural dielectric layer; patterning the single crystal substrate by an etching process on the second surface to expose a portion of the dielectric member filled in the spaces surrounding the SCS mass blocks; performing isotropic etching process at least on the dielectric portion filled in the spaces surrounding the SCS mass blocks. The SCS mass blocks are exposed to release a MEMS structure.

Abstract: Method of manufacturing a MEMS device integrated in a silicon substrate. In parallel to the manufacturing of the MEMS device passive components as trench capacitors with a high capacitance density can be processed. The method is especially suited for MEMS resonators with resonance frequencies in the range of 10 MHz.

Abstract: A process for manufacturing a component is described. In a first manufacturing step a base structure having a substrate, a diaphragm, and a cavern region is provided. The diaphragm is oriented substantially parallel to a main plane of extension of the substrate. The cavern region is situated between the substrate and the diaphragm, and has an access opening. In a second manufacturing step, a first conductive layer is provided at least partially in the cavern region, in particular on a second side of the diaphragm facing the substrate, perpendicularly to the main plane of extension.

Abstract: A process for making a latching zip-mode actuated mono wafer MEMS switch especially suited to capacitance coupled signal switching of microwave radio frequency signals is disclosed. The single wafer fabrication process used for the switch employs sacrificial layers and liquid removal of these layers in order to also provide needed permanent physical protection for an ultra fragile switch moving arm member. Latched operation of the achieved MEMS switch without use of conventional holding electrodes or magnetic fields is also achieved. Fabrication of a single MEMS switch is disclosed however large or small arrays may be achieved. A liquid removal based fabrication process is disclosed.

Abstract: Disclosed are one-port and two-port microelectromechanical structures including variable capacitors, switches, and filter devices. High aspect-ratio micromachining is used to implement low-voltage, large value tunable and fixed capacitors, and the like. Tunable capacitors can move in the plane of the substrate by the application of DC voltages and achieve greater than 240 percent of tuning. Exemplary microelectromechanical apparatus comprises a single crystalline silicon substrate, and a conductive structure laterally separated from the single crystalline silicon substrate by first and second high aspect ratio gaps of different size, wherein at least one of the high aspect ratio gaps has an aspect ratio of at least 30:1, and is vertically anchored to the single crystalline silicon substrate by way of silicon nitride.

Abstract: An MEMS element (A1) includes a substrate (1), and a first electrode (2) formed on the substrate (1). The MEMS element (A1) further includes a second electrode (3) including a movable portion (31) spaced from the first electrode (2) and facing the first electrode. The movable portion (31) is formed with a plurality of through-holes (31a). Each of the through-holes (31a) may have a rectangular cross section.

Abstract: A method for manufacturing separated micromechanical components situated on a silicon substrate includes the following steps of a) providing separation trenches on the substrate via an anisotropic plasma deep etching method, b) irradiating the area of the silicon substrate which forms the base of the separation trenches using laser light, the silicon substrate being converted from a crystalline state into an at least partially amorphous state by the irradiation in this area, and c) inducing mechanical stresses in the substrate. In one specific embodiment, cavities are etched simultaneously with the etching of the separation trenches. The etching depths can be controlled via the RIE lag effect.

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 method of forming a sensor with an embedded cavity can include forming at least one cavity (50) in a substrate (52). The cavity (50) can include at least one membrane wall (54) having a plurality of holes (64) in the membrane wall (54), the plurality of holes (64) being formed in a two-dimensional array. A piezoresistive system (58) can be mechanically associated with the membrane wall (54). The method can be a front-side or back-side process for forming the cavity (50). The membrane (54) simultaneously acts as a diaphragm and a fluid passage into the cavity (50). Such sensors can be suitable as pressure sensors, chemical sensors, flow sensors and the like.

Abstract: A closure comprising a top wall with an annular side wall depending there from. An induction foil is proximate an inner surface of the top wall and may have a ring or circular configuration. An RFID device is affixed or is integral with the closure a minimum distance from and/or orientation with the induction foil as to prevent damage to the RFID device during an induction sealing process and to reduce adverse operational effects of the RFID from the foil. The RFID may be active or passive and may be proximate or integral with the top wall or integral with the side wall of the closure. The RFID may be contained within a film wherein a portion of the film is inductively sealed to the closure.

Abstract: In a transistor and a method of manufacturing the same, the transistor includes a channel layer arranged on a substrate, a source electrode and a drain electrode formed on the substrate so as to contact respective ends of the channel layer, a gate insulating layer surrounding the channel layer between the source electrode and the drain electrode, and a gate electrode surrounding the gate insulating layer.

Abstract: A capacitive sensor includes a substrate, at least one first electrode, at least one second electrode, a sensing device, at least one anchor base, at least one movable frame, and a plurality of spring members. The first and second electrodes are disposed on the substrate, and the anchor base surrounds the first and second electrodes and is disposed on the substrate. The movable frame surrounds the sensing device. Some of the spring members connect the movable frame and the sensing device, and the other spring members connect the movable frame and the anchor base. The sensing device and the first electrode are both sensing electrodes. The movable frame is disposed above the second electrode, and cooperates with the second electrode to act as a capacitive driver.

Abstract: A capacitive microphone transducer integrated into an integrated circuit includes a fixed plate and a membrane formed in or above an interconnect region of the integrated circuit. A process of forming an integrated circuit containing a capacitive microphone transducer includes etching access trenches through the fixed plate to a region defined for the back cavity, filling the access trenches with a sacrificial material, and removing a portion of the sacrificial material from a back side of the integrated circuit.

Abstract: A method for manufacturing a micromechanical diaphragm structure having access from the rear of the substrate includes: n-doping at least one contiguous lattice-type area of a p-doped silicon substrate surface; porously etching a substrate area beneath the n-doped lattice structure; producing a cavity in this substrate area beneath the n-doped lattice structure; growing a first monocrystalline silicon epitaxial layer on the n-doped lattice structure; at least one opening in the n-doped lattice structure being dimensioned in such a way that it is not closed by the growing first epitaxial layer but instead forms an access opening to the cavity; an oxide layer being created on the cavity wall; a rear access to the cavity being created, the oxide layer on the cavity wall acting as an etch stop layer; and the oxide layer being removed in the area of the cavity.

Abstract: A method includes growing a first oxide region concurrently with a second oxide region in a substrate and forming an inlet path to the first oxide region, the inlet path exposing a first surface of the first oxide region. The method also includes removing the first oxide region to form a chamber, forming a first MOS transistor adjacent the second oxide region, and forming a second MOS transistor separated from the first MOS transistor by the second oxide region.

Abstract: An integrated circuit having a semiconductor sensor device including a sensor housing partly filled with a rubber-elastic composition is disclosed. One embodiment has a sensor chip with sensor region arranged in the interior of the housing. The sensor housing has an opening to the surroundings which is arranged in such a way that the sensor region faces the opening. The sensor chip is embedded into a rubber-elastic composition on all sides in the interior of the housing. The sensor housing has a sandwich-like framework having three regions arranged one above another, including an intermediate region with the rubber-elastic composition.

Abstract: A RF system which includes a silicon substrate formed with at least one via-hole filled with conductive material so that both sides of the silicon substrate are electrically connected with one another; at least one flat device formed on one side of the silicon substrate; and at least one RF MEMS device formed on the other side of the silicon substrate.

Abstract: The invention provides a flow sensor structure for sealing the surface of an electric control circuit and a part of a semiconductor device via a manufacturing method capable of preventing occurrence of flash or chip crack when clamping the semiconductor device via a mold. The invention provides a flow sensor structure comprising a semiconductor device having an air flow sensing unit and a diaphragm formed thereto, and a board or a lead frame having an electric control circuit for controlling the semiconductor device disposed thereto, wherein a surface of the electric control circuit and a part of a surface of the semiconductor device is covered with resin while having the air flow sensing unit portion exposed.

Abstract: A semiconductor pressure sensor comprises: a substrate having a through-hole; a polysilicon film provided on the substrate and having a diaphragm above the through-hole; an insulating film provided on the polysilicon film; first, second, third, and forth polysilicon gauge resistances provided on the insulating film and having a piezoresistor effect; and polysilicon wirings connecting the first, second, third, and forth polysilicon gauge resistances in a bridge shape, wherein each of the first and second polysilicon gauge resistances is disposed on a central portion of the diaphragm and has a plurality of resistors connected in parallel, a structure of the first polysilicon gauge resistance is same as a structure of the second polysilicon gauge resistance, and a direction of the first polysilicon gauge resistance is same as a direction of the second polysilicon gauge resistance.

Abstract: The present disclosure relates to a method of fabricating a micromachined CMOS-MEMS integrated device as well as the devices/apparatus resulting from the method. In the disclosed method, the anisotropic etching (e.g., DRIE) for isolation trench formation on a MEMS element is performed on the back side of a silicon wafer, thereby avoiding the trench sidewall contamination and the screen effect of the isolation beams in a plasma etching process. In an embodiment, a layered wafer including a substrate and a composite thin film thereon is subjected to at least one (optionally at least two) back side anisotropic etching step to form an isolation trench (and optionally a substrate membrane). The method overcomes drawbacks of other microfabrication processes, including isolation trench sidewall contamination.

Abstract: A latching zip-mode actuated mono wafer MEMS switch especially suited to capacitance coupled signal switching of microwave radio frequency signals is disclosed. The single wafer fabrication process used for the switch employs sacrificial layers and liquid removal of these layers in order to also provide needed permanent physical protection for an ultra fragile switch moving arm member. Latched operation of the achieved MEMS switch without use of conventional holding electrodes or magnetic fields is also achieved. Fabrication of a single MEMS switch is disclosed however large or small arrays may be achieved.

Abstract: The present invention relates to using an insulator layer between two metal layers of a semiconductor die to provide a micro-electromechanicalsystems (MEMS) device, such as an ohmic MEMS switch or a capacitive MEMS switch. In an ohmic MEMS switch, the insulator layer may be used to reduce metal undercutting during fabrication, to prevent electrical shorting of a MEMS actuator to a MEMS cantilever, or both. In a capacitive MEMS switch, the insulator layer may be used as a capacitive dielectric between capacitive plates, which are provided by the two metal layers. A fixed capacitive element may be provided by the insulator layer between the two metal layers. In one embodiment of the present invention, an ohmic MEMS switch, a capacitive MEMS switch, a fixed capacitive element, or any combination thereof may be integrated into a single semiconductor die.

Abstract: A micro-electro-mechanical system (MEMS) device includes a substrate, having a first side and second side, the second side has a cavity and a plurality of venting holes in the substrate at the second side with connection to the cavity. However, the cavity is included in option without absolute need. A structural dielectric layer has a dielectric structure and a conductive structure in the dielectric structure. The structural dielectric layer has a chamber in connection to the cavity by the venting holes. A suspension structure layer is formed above the chamber. An end portion is formed in the structural dielectric layer in fix position. A diaphragm has a first portion of the diaphragm fixed on the suspension structure layer while a second portion of the diaphragm is free without being fixed.

Abstract: A micro electro mechanical system (MEMS) structure is disclosed. The MEMS structure includes a backplate electrode and a 3D diaphragm electrode. The 3D diaphragm electrode has a composite structure so that a dielectric is disposed between two metal layers. The 3D diaphragm electrode is adjacent to the backplate electrode to form a variable capacitor together.

Abstract: A method of forming an inertial sensor provides 1) a device wafer with a two-dimensional array of inertial sensors and 2) a second wafer, and deposits an alloy of aluminum/germanium onto one or both of the wafers. The alloy is deposited and patterned to form a plurality of closed loops. The method then aligns the device wafer and the second wafer, and then positions the alloy between the wafers. Next, the method melts the alloy, and then solidifies the alloy to form a plurality of conductive hermetic seal rings about the plurality of the inertial sensors. The seal rings bond the device wafer to the second wafer. Finally, the method dices the wafers to form a plurality of individual, hermetically sealed inertial sensors.

Abstract: A method for manufacturing a vibration sensor including forming a sacrifice layer at one part of a front surface of a semiconductor substrate of monocrystalline silicon with a material isotropically etched by an etchant for etching the semiconductor substrate, forming a thin film protective film with a material having resistance to the etchant on the sacrifice layer and the front surface of the semiconductor substrate at a periphery of the sacrifice layer, forming a thin film of monocrystalline silicon, polycrystalline silicon, or amorphous silicon on an upper side of the sacrifice layer, opening a backside etching window in a back surface protective film having resistance to the etchant for etching the semiconductor substrate formed on a back surface of the semiconductor substrate, forming a through-hole in the semiconductor substrate by etching the semiconductor substrate anisotropically by using crystal-oriented etching by applying the etchant from the back surface window, then etching the sacrifice layer

Abstract: A method of formation of a microelectromechanical system (MEMS) resonator or filter which is compatible with integration with any analog, digital, or mixed-signal integrated circuit (IC) process, after or concurrently with the formation of the metal interconnect layers in those processes, by virtue of its materials of composition, processing steps, and temperature of fabrication is presented. The MEMS resonator or filter incorporates a lower metal level, which forms the electrodes of the MEMS resonator or filter, that may be shared with any or none of the existing metal interconnect levels on the IC. It further incorporates a resonating member that is comprised of at least one metal layer for electrical connection and electrostatic actuation, and at least one dielectric layer for structural purposes. The gap between the electrodes and the resonating member is created by the deposition and subsequent removal of a sacrificial layer comprised of a carbon-based material.

Abstract: An accurate and low cost macro pressure sensor is described. The pressure sensor includes an array of capacitive sensing elements formed at the intersections of sets of conductors. A lower set of conductors is supported by a substrate and an upper set of conductors is supported on a flexible polymer membrane. Capacitive sensing elements are formed where a conductor in the upper set overlaps a spacer in the lower set. Separators hold the membrane away from the substrate with a separation that, because of deflection of the membrane, varies in relation to the pressure applied to the membrane. As a result, the separation of conductors, and therefore capacitance, in each cell varies in response to the applied pressure. By attaching the membrane to the separators and optionally using slits in the membrane between capacitive sensing elements, measurements made in each capacitive sensing element can be mechanically decoupled.

Abstract: A manufacturing method for producing a micromechanical sensor element which may be produced in a monolithically integrable design and has capacitive detection of a physical quantity is described. In addition to the manufacturing method, a micromechanical device containing such. a sensor element, e.g., a pressure sensor or an acceleration sensor, is described.

Abstract: A capacitive ultrasonic transducer includes a first electrode, an insulating layer formed on the first electrode, at least one support frame formed on the insulating layer, and a second electrode formed space apart from the first electrode, wherein the first electrode and the second electrode define an effective area of oscillation of the capacitive ultrasonic transducer, and the respective length of the first electrode and the second electrode defining the effective area of oscillation is substantially the same.

Abstract: A pressure sensor (e.g., a condenser microphone) includes a plate having a fixed electrode, a diaphragm having a moving electrode positioned opposite to the fixed electrode, and a support, wherein the diaphragm is subjected to displacement due to pressure variations applied thereto, and the support has a first interior wall forming a first cavity, in which the end portions of the plate are fixed, and a second interior wall, in which a step portion is formed in the thickness direction of the diaphragm in relation to the first interior wall and which forms a second cavity whose cross-sectional area is larger than the cross-sectional area of the first cavity in the plane direction of the diaphragm. The first and second cavities can be redesigned to communicate with each other via a passage, whereby it is possible to improve both of low-frequency characteristics and high-frequency characteristics in the pressure sensor.

Abstract: A mechanical component production method of a MEMS/NEMS structure from a monocrystalline silicon substrate includes forming anchoring zones in one face of the substrate. A lower protective layer, non-silicon, obtained by epitaxy from the face of the substrate is formed on the face. A silicon layer obtained by epitaxy from the lower protective layer is formed on the lower protective layer. An upper protective layer is formed on the silicon layer. The upper protective, silicon and lower protective layers are etched according to a pattern defining the component, until the substrate is reached, providing access routes to the substrate. A protective layer is formed on the walls formed by the etching in the epitaxied silicon layer. The component is released by isotropic etching of the substrate from the access routes, wherein the isotropic etching does not attack the lower and upper protective layers and the protective layer of the walls.

Abstract: A method of fabricating a micro-electrical-mechanical system (MEMS) transducer comprises the steps of forming a membrane (5) on a substrate (3), and forming a back-volume in the substrate. The step of forming a back-volume in the substrate comprises the steps of forming a first back-volume portion (7a) and a second back-volume portion (7b), the first back-volume portion (7a) being separated from the second back-volume portion (7b) by a step in a sidewall of the back-volume. The cross-sectional area of the second back-volume portion (7b) can be made greater than the cross-sectional area of the membrane (5), thereby enabling the back-volume to be increased without being constrained by the cross-sectional area of the membrane (5). The back-volume may comprise a third back-volume portion. The third back-volume portion enables the effective diameter of the membrane to be formed more accurately.