Abstract:
A transducer structure is disclosed which comprises a single crystal semiconductor diaphragm dielectrically isolated by a layer of silicon dioxide from a single crystal gage configuration. The methods depicted employ high dose oxygen which is ion implanted into a monocrystalline wafer to form a buried layer of silicon dioxide with the top surface of the wafer being monocrystalline silicon. An additional layer of silicon is epitaxially grown on the top surface of the wafer to enable the etching or formation of a desired gage pattern.
Abstract:
Compensating apparatus for a shear gage transducer employing a piezoresistor. The shear gage transducer or sensor is of a cross-shaped planar configuration where a lack of symmetry in structure or in fabrication undesirably provides offsets at the output terminals associated with the horizontal cross arm. The compensating apparatus includes a series chain of resistors positioned between selected terminals of said sensor to provide a desired null output voltage over a temperature operating range. Further embodiments depict a shear sensor having a unique contact configuration to enable resistive compensation of undesired offsets.
Abstract:
A circuit for linearizing the output of a differential pressure transducer includes first and second operational amplifiers. Each amplifier is associated with threshold devices as diodes so that one amplifier will be active for one condition of output polarity while the other amplifier will be active for the other condition of output polarity. The output of the amplifiers are connected to a common terminal which provides a compensating biasing voltage to the transducer. The voltage varies in a "V" shaped characteristic to enable one to achieve a linear output voltage from the transducer for both positive and negative pressure differences.
Abstract:
There is disclosed a rectangular diaphragm employing a quasi rectangular active area. The diaphragm as configured has an aspect ratio which is the length to width ratio of greater than 3:1. The active area of the diaphragm, which is the area which most readily deflects upon application of a force to the diaphragm, is formed by an anisotropic etching technique to provide steep vertical sidewalls. The diaphragm structure thus described exhibits as a response to an applied force or pressure, a maximum longitudinal stress and a minimum transverse stress and can accommodate piezoresistive elements located within the active area of the diaphragm.
Abstract:
There is disclosed an electromechanical transducer of the type employing a semiconductor diaphragm. The diaphragm is associated with an active area upon which is mounted at least one force responsive element. Surrounding the active area of the diaphragm is an annular ridge which is located on a surface opposite that containing the element. A cylindrical housing having a central aperture is secured to the diaphragm on the same surface as the element and with its aperture coaxially aligned with the active diaphragm area. The aperture in the housing being larger than the aperture of the annular ridge and underlies the same to provide an exposed area about the periphery of the element's active area. This area is used for the deposition or location of terminals which are coupled to the element. The area is insensitive to applied force due to relative size of the ridge and housing and thus conducting leads attached to the terminals do not interfere with the specifications associated with the transducer.
Abstract:
A transducer assembly comprises a thin diaphragm of silicon having at least one piezoresistive element located in a central active area of the diaphragm. The diaphragm has a metal ring containing terminal accommodating apertures about the periphery thereof. The metal ring bounds the outermmost portion of the diaphragm designated as a non-active area. An annular housing fabricated from a high dielectric material has a series of wire accommodating grooves in a side wall thereof each one aligned with a predetermined one of said terminal accommodating apertures. The metal ring is secured to the annular housing with the active area of the diaphragm surrounded by a central aperture of the annular housing. The metal ring is secured to the housing by an electrostatic glass bond.
Abstract:
An oil-filled pressure transducer having reduced back pressure, comprising an alignment plate having a sensor accommodating aperture, a sensor module inserted into the sensor accommodating aperture, a header surrounding the alignment plate, the header having a protruding top surface, and a diaphragm disposed on the protruding top surface to create a relatively small oil accommodating region between the diaphragm and the sensor. This configuration reduces the oil volume required for operation, which ultimately reduces the back pressure applied against the diaphragm.
Abstract:
A dual diaphragm pressure transducer, or sensor, with compensation for non-pressure effects is disclosed. The pressure sensor can include two pressure transducers located on separate portions of a chip. The first pressure transducer can be a differential pressure transducer, which produces a signal proportional to one or more applied pressures and includes other non-pressure effects. The second pressure transducer can be sealed in a hermetic chamber and thus can produce a signal proportional only to non-pressure effects. The signals can be combined to produce a signal proportional to the applied pressures with no non-pressure effects. The first and second pressure transducers can be physically and/or electrically isolated to improve sealing between the two pressure transducers and prevent pressure leaks therebetween.
Abstract:
A piezoresistive sensor device and a method for making a piezoresistive device are disclosed. The sensor device comprises a silicon wafer having piezoresistive elements and contacts in electrical communication with the elements. The sensor device further comprises a contact glass coupled to the silicon wafer and having apertures aligned with the contacts. The sensor device also comprises a non-conductive frit for mounting the contact glass to a header glass, and a conductive non-lead glass frit disposed in the apertures and in electrical communication with the contacts. The method for making a piezoresistive sensor device, comprises bonding a contact glass to a silicon wafer such that apertures in the glass line up with contacts on the wafer, and filling the apertures with a non-lead glass frit such that the frit is in electrical communication with the contacts. The use of a lead free glass frit prevents catastrophic failure of the piezoresistive sensor and associated transducer in ultra high temperature applications.
Abstract:
A piezoresistive sensor device and method for making the same are disclosed. The device comprises a silicon wafer having piezoresistive elements and contacts in electrical communication with the elements. The device further comprises a contact glass coupled to the silicon wafer and having apertures aligned with the contacts. The device also comprises a non-conductive frit for mounting the contact glass to a header glass, and a conductive non-lead glass frit disposed in the apertures and in electrical communication with the contacts. The method for making the device comprises bonding a contact glass to a silicon wafer such that apertures in the glass line up with contacts on the wafer, and filling the apertures with a non-lead glass frit such that the frit is in electrical communication with the contacts. The use of a lead free glass frit prevents catastrophic failure of the device in ultra high temperature applications.