Abstract:
Stress sensitive P-N junction devices are fabricated by forming a porous layer in a semiconductor of a given conductivity, diffusing dopants of the opposite conductivity into the porous layer and forming a non-porous layer on the porous layer. This results in a microporous structure having a plurality of microcrystalline regions extending therethrough, which enhances the quantum confinement of energetic carriers and results in a device which is highly sensitive to stress.
Abstract:
The formation of porous SiC occurs under electrochemical anodization. A sample of SiC is contacted electrically with nickel and placed into an electrochemical cell which cell includes a counter electrode and a reference electrode. The sample is encapsulated so that only a bare semiconductor surface is exposed. The electrochemical cell is filled with an HF electrolyte which dissolves the SiC electrochemically. A potential is applied to the semiconductor and UV light illuminates the surface of the semiconductor. By controlling the light intensity, the potential and the doping level, a porous layer is formed in the semiconductor and thus one produces porous SiC.
Abstract:
A method of bonding a first silicon wafer to a second silicon wafer comprises the steps of diffusing a high conductivity pattern into a surface of a first semiconductor wafer, etching a portion of the surface to raise at least a portion of the pattern, providing a second semiconductor wafer having an insulating layer of a silicon compound disposed thereon, contacting the surface of the pattern to the insulating layer, and bonding the first and second semiconductor wafers at an elevated temperature.
Abstract:
There is disclosed a method of mounting a pressure transducer on a convoluted three-dimensional structure as for example a turbine blade. The method first forms a groove on a surface of a blade. The groove is formed at a given length and depth in order to accommodate a plurality of components. The groove is then filled with a ceramic material so that the top of the groove is aligned with the top surface of the structure. The entire structure is then coated with a first layer of a ceramic material which layer also covers the filled groove. Suitable conductors are then placed on the coated surface so that they span and overlie the groove. The structure is then coated with a second layer of ceramic material and the coating covers the conductors thereby serving to embed the conductors between the first and second layers. A second groove is then formed in the first and second layers which second groove overlies the first groove and which extends into the first groove. The formation of the second groove operates to separate or cut the conductors as overlying the first groove. Then ceramic material from the second layer is removed on each side of the second groove to expose the separated end surfaces of the conductors. The pressure transducer which is an integrated circuit is then placed into the second groove, and one now bonds the component terminals of the pressure transducer to the exposed conductor surfaces. In this manner both the wires leading from the transducer and the transducer itself are beneath the surface of the structure and do not interfere with the surface contours of the structure while further allowing testing of the same in all operating environments.
Abstract:
A semiconductor transducer structure is fabricated by utilizing varying height diffused layers in a sacrificial wafer. A carrier wafer has a dielectric layer on a top surface which includes a layer of glass. The sacarificial wafer, after beign subject to diffusion of highly doped semiconductor material, exhibits a plurality of varying depth regions. These regions manifest the basic transducer structure. By utilizing selective etching, one can thus form a transducer structure on the sacrificial wafer which is bonded to the carrier wafer by means of an electrostatic bond. The resultant method and structure enables one to provide transducers with improved operating characteristics which are adaptable for many different modes of operation.
Abstract:
There is disclosed a gas leak detector employing pressure transducers. In one embodiment the pressure in a vessel is monitored by means of a pressure transducer. The output of the pressure transducer is coupled to an operational amplifier whereby the amplifier has a gain which is proportional to 1/T absolute. In this manner, since the gain is inversely proportional to temperature, the amplifier will produce an output which is independent of temperature but which is capable of providing a pressure indication when there is a gas leak in the container.
Abstract:
A transducer housing consists of a first and a second section. The first section contains an internal hollow into which a transistor header is mounted. The header, as mounted in the first section, is firmly secured within the section by means of a locking ring or other arrangement. Located in the internal hollow of the first section is a printed circuit board which has a plurality of apertures on the surface thereof each of which communicates with an extending tubular post on the opposite surface. Leads from the header are directed through the apertures in the printed circuit board and extend into the tubular posts. The second housing section is emplaced on the first section and contains a series of hollow metal tubular connectors or posts. These are inserted over the metal tubular posts of the header containing the leads and are crimped so that the posts of the transistor header as well as the leads are connected both electrically and mechanically to the tubular posts extending from the second housing section. Based on the above noted configuration, the housing sections serve to hold the transducer as mounted in the header in a firm and fixed position while enabling installation and interconnection of the transistor header in a rapid and simple manner based on the fact that the leads emanating from the header are crimped internally within the housing sections.
Abstract:
A pressure transducer employs a tubular glass structure of a "D" shaped cross section, with the arcuate section of the "D" shaped configuration being substantially thicker than the base section. A sensor array is positioned on the underside of the base section while a pressure conducting fluid is directed through the tubular member to provide deflection of the base to cause the sensor array to provide an output indicative of pressure variations in the fluid medium. The sensor array as positioned on the underside of the base is both electrically and mechanically isolated from the pressure conducting medium.
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 a balancing network for a piezoresistive semiconductor bridge configuration. The balancing network comprises a plurality of series resistors arranged in series with the sensing elements in the bridge configuration. Each resistor differs from the previous one according to a power of two to form a binary ladder arrangement. The individual resistors are associated with terminals to allow the transducer manufacturer to selectively short one or more resistors to provide zero balance compensation. The resistors are located on the nonactive portion of the semiconductor substrate and are fabricated by the same techniques employed for fabrication of the semiconductor piezoresistive sensing elements to assure temperature tracking of the unit with the desired temperature operating range.