Abstract: The object of the present invention is to propose an etch channel sealing structure characterized by excellent impermeability to moisture and resistance to temporal change of the diaphragm in the pressure sensor produced according to the sacrificial layer etching technique, and to provide a pressure sensor characterized by excellent productivity and durability. After a very small gap is formed by the sacrificial layer etching technique, silicon oxide film is deposited by the CVD technique or the like, thereby sealing the etch channel. Further, impermeable thin film of polysilicon or the like is formed to cover the oxide film. This allows an etch channel sealing structure to be simplified in the pressure sensor produced according to the sacrificial layer etching technique, and prevents entry of moisture into the cavity, thereby improving moisture resistance. Moreover, sealing material with small film stress reduces temporal deformation of the diaphragm.

Abstract: The present invention relates to a measurement device for fixing to a pipe or a vessel containing a fluid, the device including a pressure sensor surrounded by a wall. The device includes a coating adhering to said wall and suitable for isolating the fluid sensor.

Abstract: A capacitive-type pressure sensor comprising a glass plate having an electrode formed thereon. A diaphragm is formed from a semiconductor material and bonded to the glass substrate to define an enclosed cavity containing at least a portion of the electrode, to thereby define a capacitive element, through which, in use, an electrical signal may be passed to determine a capacitance thereof which is indicative of the pressure to be determined.

Abstract: A method of manufacturing strain-detecting devices is provided. First, plural cylindrical substrates, each of which has one end closed by a diaphragm, are fixedly placed at predetermined positions of a fixing plate. A positioning marker is previously given to the fixing plate. The fixing plate having the substrates is then assembled into a jig. The jig sustains the substrates so that an outer surface of the diaphragm of each substrate is held at the same level. Through positioning the substrates, all the diaphragms are then positioned in place in a plane direction of the fixing plate with reference to the positioning marker. A strain gage portion is simultaneously formed on each of all the diaphragms. The fixing plate is then disassembled from the jig. In this step, the substrates with the strain gage portions, i.e., strain-detecting devices, are separated from the fixing plate.

Abstract: A capacitive sensor is disclosed that includes a variable capacitor transducer that varies its capacitance with changes in an environmental parameter. The present invention is adapted to measure any linear parameter such as pressure, force, or distance. The sensor the present invention is compact, inexpensive to make, and easily fabricated using commonly available components. Furthermore, it is not susceptible to errors caused by vibration, acceleration, and its orientation to the earth's gravitational field. The output of the capacitive sensor does not substantially drift with changes in temperature.

Abstract: A diaphragm-type semiconductor device includes a semiconductor substrate, a surface of which is substantially flat, a diaphragm, which covers a circular pressure reference space located on the surface, and a circular electrode layer, a middle part of which is embedded in the diaphragm. The electrode layer is larger than the space and is coaxial with the space. Therefore, internal stress is balanced between inner and outer sides of the diaphragm, and a step formed at the outer edge of the top electrode layer is separated from the diaphragm. The device also includes a step adjuster around the space on the surface. Therefore, another step formed at the outer edge of the space disappears, and a new step is formed separately from the diaphragm at the outer edge of the step adjuster. With this structure, the diaphragm has a desired flatness.

Abstract: In an electrostatic capacitance sensor, an electrode is formed on a base board. The electrode is covered with a resist. A conductive rubber includes a first face and a second face. The first face has a fist area and is opposed to the resist. The second face is opposed to the first face. The second face has a second area which is larger that the first area. A flexible click rubber is attached to the second face of the conductive rubber for providing pressure contact of the conductive rubber with respect to the resist.

Abstract: A capacitive fluid pressure transducer (10′) has a sensing element (12) received in an electrically conductive cup-shaped shield member (24) which is crimped onto the base of an electrical connector (20′). A conditioning circuit (14) is received in a circuit chamber formed between the sensor element and the connector and is provided with a tab carrying a conductive trace for electrical connection of the shield member with the circuit. The shield member is received in an electrically insulating sleeve (28) which in turn is received in a cavity formed in a metallic, high strength hexport housing so that the shield member is electrically isolated from the hexport housing.

Abstract: A pressure-measuring device with monitoring for diaphragm fracture comprises a housing with a passage whose two openings at the end faces of the housing are closed by a first deformation body and a second deformation body. The passage is completely filled with a transmission liquid in order to transmit the process pressure from the first deformation body to the second deformation body. The device has components for monitoring a material property of the transmission liquid. A change in the material property indicates contamination by the process medium and thus a fracture of the first deformation body. The material property monitored is preferably the relative dielectric constant.

Abstract: A micromechanical differential pressure sensor device for measuring a pressure difference between two mutually separated spaces or media, in which two absolute pressure measuring devices are monolithically integrated on a single support substrate, in particular on a semiconductor chip. The absolute pressure measuring devices are preferably fabricated by surface micromachining.

Abstract: A method for making capacitive silicon pressure sensors and pressure switches with high long-term stability involves fabrication by wafer bonding of a silicon substrate wafer with another silicon wafer where a highly boron-doped diaphragm is defined by a self-aligned doping process through a window defined on an insulating layer. The long-term stability of the device is secured by anisotropically etching the window, e.g. by reactive ion etching, so as to create vertical window walls. The flatness of the diaphragm can be secured by the provision of an insulating film on the backside of the substrate wafer that compensates the stress on the silicon diaphragm created by the insulating layer present between the two wafers. The cavity formed by the window may contain gas or it may be evacuated in which case the fabrication method may also involve a process step facilitating the evacuation of the cavity and sealing the same using metal employed for making electrical connections.

Abstract: The invention concerns a pressure sensor (1), able to operate at high temperature and measure the pressure of a hostile medium, comprising: a sensing element (4) integrating a membrane (8) in monocrystalline silicon carbide, made by micro-machining a substrate in polycrystalline silicon carbide, a first surface of membrane (8) intended to contact said medium, a second surface of membrane (8) comprising membrane deformation detection means (9) connected to electric contacts (10) to connect electric connection means (11), the surfaces of sensing element (4) contacting said medium being chemically inert to this medium; a carrier (5) to support sensing element (4) so that said first surface of membrane (8) may be contacted with said medium and the second surface of membrane (8) may be shielded from said medium, carrier (5) being in polycrystalline silicon carbide; a seal strip (6), in material containing silicon carbide, brazed between carrier (5) and sensing element (4) to protect the second surface of membra

Abstract: A sensor, in particular a humidity sensor, comprises a measuring layer (4), the dielectric properties of which depend on a parameter to be measured, e.g. of the humidity of the environmental air. Electrodes (2, 3) are arranged on a substrate (1) side by side for capacitively measuring the measuring layer (1). A protective layer (8) of a non-oxidizing material, in particular a layer of silicon oxide or gold, is arranged between the electrodes (2, 3) and the measuring layer (4). This layer prevents an oxidation of the electrodes (2, 3) and increases the live time and reliability of the sensor.

Abstract: An in-situ sensor system and method which measures the density of a liquid accurately with pressure sensors by measuring pressure in the liquid at two separate positions defined by a fixed distance. The fixed distance is known accurately to at least the nearest 0.0001 inch by measuring temperature simultaneously with pressure measurements. The temperature is used to correct for temperature-related changes in length of the material to which the pressure sensors are fixed. Because pressure sensors and temperature sensors can be relatively small, the sensor system is small, portable, and can be easily and safely inserted into or removed from tanks through a small opening. A data acquisition system acquires data with a remote telemetry system, provides the data to users through a communications network, and provides density, height, volume, and leak rate of the liquids using one or more data management systems.

Abstract: A capacitor industrial process control transmitter includes a three-phase excitation circuit to charge a sensing capacitor and a compensation capacitor of the transmitter and transfer charges to an integrator. The sensing capacitor is charged during the first phase. During the second phase, the voltage to the sensing capacitor is reversed, and the charge on the sensing capacitor is pumped to the integrator. Also, the compensation capacitor is charged with the reversed voltage during the second phase. During the third phase, the voltage to the compensation capacitor is changed, and the charge on the compensation capacitor is pumped to the integrator.

Abstract: A transducer with at least one variable-area capacitor comprising a flexible electrode with a surface facing a surface of a cooperating rigid electrode and an electret affixed to a portion of one of said surfaces, wherein said surface of said rigid electrode has a contoured region selected to increase a region of substantially fixed capacitance spacing as said flexible electrode deflects in response to an applied stress.

Abstract: A pressure sensor using two capacitors for measuring a pressure stimulus includes a substrate having a diaphragm positioned at a center portion thereof. The diaphragm has a reduced thickness so that the diaphragm displaces upward and downward in response to a pressure stimulus. A first capacitor is provided on the diaphragm and at least a second capacitor is provided on a bulk portion of the substrate so as to be adjacent to the first capacitor. The first and the second capacitor are connected to each other in series, wherein capacitance differs between the first and the second capacitor when the diaphragm moves up and down in response to the pressure stimulus.

Abstract: A sensor having freeze resistant features is disclosed. The sensor includes a sensor die and a buffer member that are assembled for attachment to a process fluid conduit. The buffer member defines an opening in fluid communication with the process fluid. The sensor die has a flexible diaphragm, and a capillary channel establishes fluid communication between the diaphragm area of the sensor die and the opening in the buffer member.

Abstract: A method of manufacturing a transducer of the type having a diaphragm (11) with a predetermined tension. After the transducer has been manufactured with its basic structure the diaphragm is adjusted to have a predetermined tension, which is preferably low in order to obtain a high sensitivity. Two embodiments are disclosed. One embodiment includes heating the transducer to a temperature above the glass transition temperature of the material (12, 14) retaining the diaphragm. Another embodiment includes measuring the actual tension of the diaphragm, which can be used to calculate an adjustment of the thickness of the diaphragm resulting in the desired tension.

Abstract: A pressure measuring device with a housing (21, 53) and a pressure measuring cell is provided, the pressure measuring cell being protected from interference, in particular independently of its installation position in the housing (21, 53), and comprising: a housing (21, 53), a pressure measuring cell, which has at least one pressure-sensitive measuring diaphragm (3, 35, 37), on the outer side of which a pressure (P, P1, P2) acts during operation, which has a transducer for converting a pressure-dependent deflection of the measuring diaphragm (3, 35, 37) into an electrical measured variable and which has free outer circumferential surfaces, which are provided with an electrically conductive coating (31, 61), and an electronic circuit (13, 49) for converting the electrical measured variable into a measuring signal.

Abstract: A pressure sensor is formed by sandwiching a pressure-sensitive dielectric membrane between and in contact with a pair of electrodes. As pressure is applied, the dielectric constant of the pressure-sensitive membrane changes while the distance of separation between the pair of electrodes remains constant. This change in the dielectric constant is detected by a circuit as a change in the electrostatic capacitance between the electrodes to measure the applied pressure. Since the pressure-sensitive dielectric membrane is not required to undergo any elastic deformation for measuring the pressure, the pressure sensor can be made extremely thin.

Abstract: A pressure sensor having a first pole element and a second pole element spaced apart from each other and forming a capacitor. The first pole element includes a substantially flat portion around which the second pole element is bent forming a bent edge portion of the second pole element. The bent edge portion is located at a distance from the substantially flat portion. The length of the distance and, thereby, the capacitance of the sensor, varies as a function of a loading state of the sensor. The sensor is well suited for use as an occupant detector in automotive seating applications.

Abstract: A new type of high-Q variable capacitor includes a substrate, a first electrically conductive layer fixed to the substrate, a dielectric layer fixed to a portion of the electrically conductive layer, and a second electrically conductive layer having an anchor portion and a free portion. The anchor portion is fixed to the dielectric layer and the free portion is initially fixed to the dielectric layer, but is released from the dielectric layer to become separated from the dielectric layer, and wherein an inherent stress profile in the second electrically conductive layer biases the free portion away from the a dielectric layer. When a bias voltage is applied between the first electrically conductive layer and the second electrically conductive layer, electrostatic forces in the free portion bend the free portion towards the first electrically conductive layer, thereby increasing the capacitance of the capacitor.

Abstract: A high-accuracy high-stability capacitor type pressure sensor which eliminates a parasitic capacitance between a reference capacitor and a semiconductor substrate. A capacitor type pressure sensor comprising, on a semiconductor substrate 10, an active capacitor 100 whose capacitance varies as the surrounding pressure varies, a reference capacitor 200 whose capacitance will not vary substantially as the surrounding pressure varies, and a circuit which is electrically connected to both said active and reference capacitors 100 and 200, detects the difference or ratio thereof, and uses the potential of a semiconductor substrate, wherein an electrode 30a of said reference capacitor is formed on the semiconductor substrate 10 with a dielectric 20 therebetween.

Abstract: A micromechanical component placed on a substrate face includes at least one cell. A counter-electrode of a cell capacitor is placed under a cavity. The counter-electrode can be made from a first part of a lower conductive layer. An optionally circular membrane used as an electrode of the capacitor is placed above the cavity. The membrane is homogeneous, has a substantially uniform thickness, and can be part of an upper conductive layer preferably supported by a second part of the lower conductive layer. A caustic channel used to remove the sacrificial coating in order to form the cavity is laterally connected thereto. The channel has a vertical dimension equal to the vertical dimension of the cavity. A closure is adjacent to the channel and disposed outside the membrane. The component can be used as a pressure sensor, and can have several cells each adjacent to six other cells. A process for fabricating a micromechanical component is also provided.

Abstract: The method for producing a micromechanical component includes the following steps: producing a semi-finished micromechanical component; producing openings and forming a cavity; sealing the opening with sealing lids; removing material on the top surface of the first membrane layer, the surface of the first membrane layer being exposed and planarized. The invention also relates to a micromechanical component which can be produced according to the above method and to its use in sensors such as pressure sensors, microphones, or acceleration sensors.

Abstract: A capacitive pressure sensor for measuring a pressure applied to an elastic member includes a capacitive plate disposed adjacent to the elastic member so as to define a gap between a planar conductive surface of the elastic member and a corresponding planar surface of the capacitive plate. The gap, capacitive plate and elastic member together define a capacitor having a characteristic capacitance. The sensor further includes an elongated electrical conductor characterized by an associated inductance value. The conductor is fixedly attached to and electrically coupled with the capacitive plate. The gap between the capacitive plate and the elastic member varies as a predetermined function of the pressure applied to the elastic member so as to vary the characteristic capacitance. The capacitor and the electrical conductor together form an electrical resonator having a characteristic resonant frequency. Varying the capacitance of this tank circuit varies the resonant frequency of the tank circuit.

Abstract: A method for the formation of a region of silicon dioxide on a substrate of monocrystalline silicon. The epitaxial growth of a silicon layer, the opening of holes in the silicon layer above the silicon dioxide region, and the removal of the silicon dioxide which constitutes the region by means of chemical attack through the holes until a silicon diaphragm, attached to the substrate along the edges and separated therefrom by a space, is produced. In order to form an absolute pressure microsensor, the space has to be sealed. To do this, the method provides for the holes to have diameters smaller than the thickness of the diaphragm and to be closed by the formation of a silicon dioxide layer by vapor-phase deposition at atmospheric pressure.

Abstract: Manufacturing all-silicon force sensors, such as capacitive pressure sensors (100, 200) that have long term stability and good linear sensitivity, and can be built into of a pneumatic tire. The sensors include buried electrical feedthrough (112b) to provide an electrical connection into a sealed silicon cavity (108). The buried feedthrough consists of a conductor (112b) in a shallow groove (106) in a substrate (102), communicating between the sensing cavity (108) and an external contact area (110). The sensor designs also feature a method for forming a silicon-to-silicon fusion bond (SFB) wherein at least one of the two surfaces (152, 252) to be has a tough silicon surface unsuitable for good SFB joints because it was bonded heavily boron-doped by means of diffusion. The method of this invention includes preparing each doped surface (152, 252) for SFB by polishing the surface with a Chemical-Mechanical Polishing (CMP) process.

Abstract: A micro electro-mechanical systems device having variable capacitance is controllable over the full dynamic range and not subject to the “snap effect” common in the prior art. The device features an electrostatic driver (120) having a driver capacitor of fixed capacitance (121) in series with a second driver capacitor of variable capacitance (126). A MEMS variable capacitor (130) is controlled by applying an actuation voltage potential to the electrostatic driver (120). The electrostatic driver (120) and MEMS variable capacitor (130) are integrated in a single, monolithic device.

Abstract: A MEM capacitor having a capacitance plate nearer a movable plate than a separate bias plate. Voltage potential between the bias plate and movable plate determines the value of capacitance between the movable plate and the capacitance plate. In a preferred MEM capacitor, the movable plate is suspended over two fixed plates, a bias plate and a capacitance plate. The movable plate is disposed opposite both the bias plate and the capacitance plate. A distance between opposing surfaces of the capacitance plate and the movable plate is less than a distance between the bias plate and the capacitance plate. Preferably, the relative difference in distances between the plates is accomplished by a mechanically suspended movable plate that is shaped to have portions in at least two separate planes.

Abstract: The invention is concerned with a pressure sensor which avoids temperature hysteresis effects caused on account of heat-induced expansions as a result of stresses between a ceramic pressure-measuring cell and a metallic housing. The inventive pressure sensor (100) for determining the pressure of a process medium comprises a metallic housing (110), which is open to a process medium and has a continuous hole (111) for accommodating the ceramic pressure-measuring cell (120), the pressure-measuring cell (120) comprising a ceramic base body (122) and a ceramic diaphragm (121), which is fitted thereon and is exposed to the process medium, and also suitable means (124a, 124b, 130), which supply an electrical signal which can be picked off and corresponds to the process pressure acting on the diaphragm (121).

Abstract: Structures and methods are disclosed in conjunction with the fabrication of electrical lead transfer feedthroughs with respect to a sealed cavity. In some applications such as capacitive pressure sensing, the cavity may include an outer wall, in which case the electrically insulating barrier is preferably U-shaped, with the ends of the U terminating at the outer wall. The feedthrough section may alternatively take the form of an island of conductive material surrounded by the electrically insulating barrier, thus assuming an O-shape. The cavity may be evacuated or filled with specific gases at specific pressures. As such, the invention finds application in the packaging (vacuum or controlled environment) and production of a variety of transducers including but not limited to pressure sensors, flow sensors, optical devices (e.g., infrared detectors, ccd camera, and flat-panel displays) and resonating devices, such as gyroscopes, accelerometers, yaw sensors, telecommunication devices, etc.

Abstract: These capacitive pressure sensor cells have joints between substrates and diaphragms being both pressure and/or tension-proof and high-vacuum-tight and long-term-stable. The sensor cell comprises a ceramic substrate (1) having a cylindrical surface (11), a major surfaces (12, 13). The major surface (12) includes a concave central area (121) merging, in the direction of and up to said cylindrical surface (11), into a convex surface (124) having a vertex line (125) and forming a planar ring surface (126) in its area. An electrode (122) is located in the concave area (121). An electrical connection (123) extends from electrode (122) through the substrate (1) to surface (13). A ceramic diaphragm (5) has a planar inner surface (51) on which an electrode (52) is located and which rests on the ring surface (126) of the substrate (1).

Abstract: A capacitive pressure sensor includes a housing element, a first electrode assembly and a second electrode assembly. The first electrode assembly includes a deformable elastic member, and a plurality of petal electrodes. The petal electrodes are attached to the elastic member and extend from the elastic member in a direction which is substantially perpendicular to the surface of the elastic member. The elastic member of the first electrode assembly is secured at its perimeter to the housing element at an aperture in the housing, so that the petal electrodes are enclosed within the housing. The second electrode assembly is also enclosed within the housing and is surrounded by the elongated electrodes. The spatial relationship between the petal electrodes and the second electrode assembly is directly related to the capacitance measured between them.

Abstract: A capacitance-type pressure sensor unit capable of being assembled without applying a pressure at an increased level to a circuit board. A connector body (6) has a base (6b) received in a peripheral wall section (13b) of a receiving casing (13) constituting a main body of the casing (13) and fixed to an end (13e) of the peripheral wall section (13b) by caulking. A pressure sensor element (3) constituted of a first insulating substrate (1) and a second insulating substrate (2) is arranged in a bottom wall section (13a) of the receiving casing (13) and a fluid chamber (15) into which pressure measured fluid is introduced is defined between a rear surface of the first insulating substrate (1) and the bottom wall section (13a).

Abstract: A semiconductor component (31) and a method for coupling a semiconductor device (36) to a substrate (81). The semiconductor component (31) includes a saddle (34) and the semiconductor device (36). The saddle (34) has a plurality of sides (51, 52, 53, 54, 55) that form a semiconductor device receiving area (58). The semiconductor device (36) is inserted into the semiconductor device receiving area (58) and secured in the semiconductor device receiving area (58) using tabs (66, 67). The saddle (34) is coupled to the substrate (81) by fasteners (82,83).

Abstract: In a capacitance type pressure sensor, a diaphragm is formed of a fragile material using an impurity-diffused monocrystal silicon and constitutes a stable pressure-responsive structure which does not undergo a plastic deformation. Between the diaphragm and a movable electrode is formed an oxide film to diminish stray capacitance between the movable electrode and a substrate and also between the movable electrode and a impurity-diffused layer. The oxide film and the movable electrode are each divided into plural regions so that the divided regions of the movable electrode are formed on the divided regions of the oxide film, thereby diminishing stress strain induced by a difference in therm expansion coefficient among the diaphragm, oxide film and movable electrode.