Continental Automotive Systems Corporation

Motorola Corporation

Vitesco Technologies Usa, LLC

Temic Automotive of North America, Inc.

Shiuh-Hui Steven Chen

Jen-Huang Albert Chiou

Carl A Ross

Robert Charles Kosberg

Joe Pin Wang

Raymond Garza

Stefan Turalski

Marc Kenneth Chason

Xiaoyi Ding

Jeffrey J Frye

Donald L Hughes, Jr

Joseph P Tomase

Didier Lefebvre

Yanling Kang

Gregory D Stamm

Anita G Brandes

Cheryl B Field

Sut-Mui Tang

Roseann M Tomasello

Arthur J Edwards

Daniel Roy Empen

Carl Ross

A pressure sensing element, including a substrate, a device layer coupled to the substrate, a diaphragm being part of the device layer, and a plurality of piezoresistors coupled to the diaphragm. A plurality of bond pads is disposed on the device layer, and an electrical field shield is bonded to the top of device layer and at least one of the bond pads. At least one stress adjustor is part of the electrical field shield, where the stress adjustor is a cut-out constructed and arranged to reduce thermal hysteresis of the pressure sensing element caused by stress relaxation of the electrical field shield during a cooling and heating cycle. The stress adjustor may be a thin film deposited on top of the electrical field shield, which may apply residual stress to the piezoresistors. The pressure sensing element may include a cavity integrally formed as part of the substrate.

Mems pressure sensing element with stress adjustors to minimize thermal hysteresis induced by electrical field

A pressure sensing element includes a supporting substrate including a cavity. A device layer is bonded to the supporting substrate, with a diaphragm of the device layer covering the cavity in a sealed manner. A plurality of piezoresistors is coupled to the diaphragm. A plurality of metal stress equalizers is disposed on the device layer such that each stress equalizer is generally adjacent to, but separated from, a corresponding piezoresistor. A plurality of metal bond pads is disposed on the device layer. The plurality of stress equalizers are constructed and arranged to reduce thermal hysteresis of the pressure sensing element caused by stress relaxation of the metal bond pads during a cooling and heating cycle of the pressure sensing element.

CSOI MEMS pressure sensing element with stress equalizers

An improved microelectromechanical system (MEMS) pressure sensing device has an extended shallow polygon cavity on a top side of a silicon supporting substrate. A buried silicon dioxide layer is formed between the top side of the supporting substrate and a bottom side of a device layer. Piezoresistors and bond pads are formed and located on a top side of the device layer and produce measureable voltage changes responsive to a fluid pressure applied to the device layer. The purpose of the extend shallow polygon cavity is to improve the sensitivity or increase the span while keep a low pressure nonlinearity during shrinking the die size of the MEMS pressure sensing device die with corner metal bond pads having a keep-out distance to prevent a wire bonder from breaking the thin diaphragm.

Cavity with silicon on insulator MEMS pressure sensing device with an extended shallow cross-shaped cavity

Suspending a microelectromechanical system (MEMS) pressure sensing element inside a cavity using spring-like corrugations or serpentine crenellations, reduces thermally-mismatched mechanical stress on the sensing element. Overlaying the spring-like structures and the sensing element with a gel further reduces thermally-mismatched stress and vibrational dynamic stress.

Stress-isolated absolute pressure sensor

The voltage output span and sensitivity from a MEMS pressure sensor are increased and pressure nonlinearity is reduced by thinning a diaphragm and forming the diaphragm to include anchors that are not connected to or joined to diaphragm-stiffening beams or thickened regions of the diaphragm.

Pressure sensor device with anchors for die shrinkage and high sensitivity

In a microelectromechanical system (MEMS) pressure sensor, thin and fragile bond wires that are used in the prior art to connect a MEMS pressure sensing element to an application specific integrated circuit (ASIC) for the input and output signals between these two chips are replaced by stacking the ASIC on the MEMS pressure sensing element and connecting each other using conductive vias formed in the ASIC. Gel used to protect the bond wires, ASIC and MEMS pressure sensing element can be eliminated if bond wires are no longer used. Stacking the ASIC on the MEMS pressure sensing element and connecting them using conductive vias enables a reduction in the size and cost of a housing in which the devices are placed and protected.

3D stacked piezoresistive pressure sensor

Electrical and mechanical noise in a microelectromechanical system (MEMS) pressure sensor are reduced by the symmetrical distribution of bond pads, conductive vias and interconnects and by the elimination of bond wires used in the prior art to connect a MEMS pressure sensing element to an application specific integrated circuit (ASIC). The bond wires are eliminated by using conductive vias to connect an ASIC to a MEMS pressure sensing element. Extraneous electrical noise is suppressed by conductive rings that surround output signal bond pads and a conductive loop that surrounds the conductive rings and bond pads. The conductive rings and loop are connected to a fixed voltage or ground potential.

Symmetrical piezoresistive pressure sensor with stacking ICs

The voltages output from a low-pressure MEMS sensor are increased by increasing the sensitivity of the sensor. Sensitivity is increased by thinning the diaphragm of the low pressure sensor device. Nonlinearity increased by thinning the diaphragm is reduced by simultaneously creating a cross stiffener on the top side of the diaphragm. An over-etch of the top side further increases sensitivity.

Piezoresistive pressure sensor device

The voltages output from a low-pressure MEMS sensor are increased by increasing the sensitivity of the sensor. Sensitivity is increased by thinning the diaphragm of the low pressure sensor device with corner trench. Nonlinearity increased by thinning the diaphragm is reduced by simultaneously creating a cross stiffener to the bottom side of the diaphragm. A rim, anchors, and a stiffener pad can also be added to further stiffen the thinner diaphragm and further reduce pressure nonlinearity.

Pressure sensor device with high sensitivity and high accuracy

In a MEMS PRT having a diaphragm that is located offset from the center of the die, thermally-induced thermal noise in the output of a Wheatstone bridge circuit is reduced by locating the Wheatstone bridge circuit away from the largest area of the die and supporting pedestal.

Piezoresistive transducer with low thermal noise

An MEMS pressure sensor is designed to reduce or eliminate thermal noise, such as temperature offset voltage output. The pressure sensor includes a pressure sensing element having a diaphragm, and a cavity formed as part of the pressure sensing element, where the cavity receives a fluid such that the diaphragm at least partially deflects. The pressure sensing element also includes a plurality of piezoresistors, which are operable to generate a signal based on the amount of deflection in the diaphragm. At least one trench is integrally formed as part of the pressure sensing element, and an adhesive connects the pressure sensing element to the at least one substrate such that at least a portion of the adhesive is attached to the trench and redistributes thermally induced stresses on the pressure sensing element such that the thermally induced noise is substantially eliminated.

Semiconductor sensing device to minimize thermal noise

In a pressure sensing element made of piezoresistors formed into a silicon substrate, thermally-induced stresses on the piezoresistors and thermally-induced voltage offsets can be reduced by thinning the substrate prior to forming the resistors and then forming the resistors into the thinned-out recess. Forming a circular or disk-shaped recess in the substrate and then forming the resistors therein is believed to cause thermally-induced stresses to be evenly distributed and/or cancelled out on all four piezoresistors of a Wheatstone bridge circuit.

Robust design of high pressure sensor device

Dual piezoresistive transducers formed into a single silicon die, are anodically bonded to a pedestal. Two separate pressure ports extend through a plastic housing. The port openings inside the housing are surrounded by a groove having a shape and size that accepts the pedestal. A thin, liquid adhesive is deposited into the groove and allowed to level out. The pedestal is placed into the adhesive and embeds itself therein. Adhesive overflow into the ports is avoided by dimensioning the groove and depositing an amount of adhesive that will fill the groove but not overflow when the pedestal is placed therein. Once the adhesive cures, the adhesive bond strength is greater due to the adhesive being in shear relative to the groove side walls and pedestal sidewalls. The grooved structure provides an apparatus and methodology for precise die mounting and media sealing.

Grooved structure for die-mount and media sealing

Pressure non-linearity in a low pressure sensor device formed from a silicon diaphragm with an embedded piezoresistive transducer is reduced by using a shallow boss or thin stiffener on an ultra-thin diaphragm while the pressure sensitivity of the device is increased with corner trenches.

Low pressure sensor device with high accuracy and high sensitivity

An accelerometer or accelerator switch and its method of manufacture are disclosed. The device is fabricated from two substrates: a top substrate having a moveable mass, and a bottom substrate having at least one conductive plate. The top substrate is preferably a SOI substrate, and the mass and its suspending beams are formed in the silicon layer under which the insulator layer has been removed. The bottom substrate is preferably oxide. In one embodiment, the capacitance is formed using the mass as the first capacitor plate the conductive plate as the second plate. As the mass moves, the capacitance is detected to indicate the magnitude of the acceleration, or whether acceleration is above or below a threshold indicting an open or closed switch. The beams which suspend the mass can be serpentines, which make the device compact and render the mass more flexible. Alternatively, the bottom conductive plate can be split into two plates each coupling to the mass. Depending on the capacitance between the two split plates, this configuration allows for the formation of either a normally-open or normally-close acceleration switch.

Growing community of inventors

Lake Zurich, IL, United States of America

Shiuh-Hui Steven Chen