Abstract:
A method of epitaxially depositing onto a semiconductor substrate by planarizing the deposition surface of the substrate substantially parallel to a predetermined crystallographic plane, forming a deposition mask which exposes a predetermined site on the surface of the substrate, and epitaxially depositing semiconductor material in a preferred growth direction at the exposed site to produce a monocrystalline structure. A plurality of sites may be exposed through the deposition mask to permit formation of a plurality of discrete monocrystalline structures having predetermined spacing. Layers of different conductivity types can be formed in the structures by selective doping during deposition. Monocrystalline structures formed by the above method may be coated with a dielectric material and further processed to produce semiconductor devices for use in integrated circuits. If the monocrystalline structures are suitably arrayed and of a different conductivity type than the substrate, thus yielding semiconductor diodes, they can be utilized as a target in a vidicon tube.
Abstract:
The stainless steel surface of a strip of composite, rollbonded, stainless steel-aluminum laminate material is characterized by a matte finish and by considerable surface roughness but is shown to be provided with a high quality surface finish in an economical manner by advancing the metal laminate over spaced supporting rolls under substantial tension, by providing a series of buffing rolls formed of fabrics of moderate abrading properties and by rotating these buffing rolls in the direction of advance of the laminate on roll axes disposed normal to said direction of advance while oscillating the buffing rolls to a controlled limited extent along the roll axes and while pressing the buffing rolls against the stainless steel surface between the support rolls with substantial force for obtaining a selected degree of wrap of the laminate against surfaces of the buffing rolls to provide a substantial area of buffing engagement between the strip surface and the rolls, and by intermittently projecting abrasive particles of moderate abrading properties free of a gaseous carrier medium at a force in excess of 600 psi, substantially radially onto surfaces of the buffing rolls for penetrating the buffing rolls with the abrasive particles to a significant extent so that the abrasive particles are carried by the buffing rolls over the entire area of buffing engagement between the strip surface and the rolls, thereby to obtain an extensive degree of a moderate type of surface abrasion for achieving the desired high quality surface finish while using only limited quantities of expendable buffing and abrasive materials.
Abstract:
Disclosed is a method which utilizes an insulated gate fieldeffect semiconductor device having a gate isolation comprised of at least two different gate isolation materials as a programmable non-volatile memory. Writing into the memory is accomplished by increasing the threshold voltage from its intrinsic device level to a second more positive level by trapping charges of one polarity in the gate isolation layers. Erasing the memory is accomplished by injecting into the gate isolation layers charges of opposite polarity, thereby neutralizing the previously stored charge and causing the modified device threshold voltage to return to substantially the intrinsic value.
Abstract:
This disclosure relates to a semiconductor device structure defining an interdigitated P-N junction diode, wherein a plurality of raised protuberances forming elevated mesas are provided on a semiconductor substrate of one conductivity type. The mesas respectively include a semiconductor region of the other conductivity type forming the top portion thereof so as to define a plurality of parallel elongated fingers in spaced apart relation to each other of the conductivity type opposite from that of the substrate and the remaining portions of the mesas. The elongated fingers of the semiconductor region are interlaced alternately with surface portions of the substrate to define an interdigitaed arrangement therebetween. Electrically conductive contact members are respectively fixedly mounted on the fingers defining the semiconductor region of the other conductivity type and the surface of the substrate, with the electrically conductive contact members having respective configurations conforming to the elongated fingers of the semiconductor region and the surface portions of the substrate. Thus, the electrically conductive contact members provide an interdigitated arrangement between alternating contact fingers thereof, with each electrically conductive contact member including a web portion joining the contact fingers thereof and concluding in a conductor portion extending away from the interdigitaed arrangement. In a particular application, a plurality of such semiconductor devices are serially joined by the conductor portions of the electrically conductive contact members which define beam leads. Parasitic lead inductance is reduced by the beam leads and also by the interdigitated arrangement of the several P-N junctions. The structure provides a series diode array having particular application in microwave integrated circuits as a frequency multiplier for microwave frequencies in phased array radar modules.
Abstract:
Method and means for providing a relatively constant ambient for temperature sensitive devices is disclosed. The method includes the steps of forming an enclosure, in which the controlled ambient will lbe effected, at least partially, of a positive temperature coefficient of resistance (hereinafter referred to as PTC) material and applying a voltage to the PTC material. The material acts as a heater and also as its own temperature regulator. The enclosure is formed, at least partially, by various structures or means including a single hollow cylindrical element, a stack of annular discs and two or more pieces of PTC material. Another embodiment discloses a design particularly useful with transistor-type devices while yet another is particularly useful with diode-type devices. Several materials are disclosed which exhibit a PTC characteristic.
Abstract:
The disclosure relates to a mask for use in X-ray lithography wherein a window is provided for X-rays, a pattern being placed over the window which absorbs the X-rays along the pattern, thereby providing a mask to the X-rays in accordance with the pattern and causing the X-rays to strike a mask on a device at all points except where the X-rays have been masked. Photoresist systems which are responsive to X-rays are well known, these including polymethylmethacrylate. The mask is formed from a thin layer of silicon carbide with a ring of material supporting the silicon carbide, preferably silicon. The desired pattern is then formed on the silicon carbide, using a material which absorbs Xrays, such as gold. The mask is formed by utilizing a starting substrate such as silicon and depositing a thin layer of silicon carbide thereon. The silicon is then etched down to the silicon carbide at all points except for the perimeter of the silicon carbide or in segments such as quadrants to provide a support for the silicon carbide. The silicon carbide is thin and acts as a window to Xrays. An X-ray absorbing mask is then formed on the silicon carbide window to provide the final X-ray lithograph mask.
Abstract:
A relay which is operable at very low power levels and which is highly versatile in its applications is shown to be characterized by high gain and high reliability and by simplicity of structure. The relay comprises a first terminal mounted on a base of electrically insulating material and a second electrically conductive member having a terminal portion secured to the base, having a contact arm movable between an open circuit position spaced from the first terminal and a closed circuit position engaging the first terminal, and having integral spring portions connecting the contact arm and terminal portion of the second member for normally biasing the contact arm to one of the noted circuit positions. The relay also includes an actuator wire secured between the base and the contact arm of the second member. The actuator wire is formed of a nickel-titanium alloy and is adapted to be deformed from an original length to a second length as the contact arm is moved to the one circuit position in response to the noted spring bias while the wire material displays a relatively low modulus of elasticity below a transition temperature. The actuator wire is also adapted to abruptly return to its original length and to display a relatively higher modulus of elasticity to move the contact arm to the other circuit position against the spring bias when the wire material is heated above its transition temperature. Means are provided for electrically self-heating the actuator wire to its transition temperature when relay operation is desired.
Abstract:
A strip of composite metal laminate material embodying a thin inner layer of stainless steel sandwiched between and metallurgically bonded to two relatively thicker outer layers of low carbon steel is subjected to a brief, high temperature heat treatment followed by a relatively much longer heat treatment at much lower temperature for substantially eliminating the yield point in the laminate and for maximizing formability, of the laminate while permitting some reduction in the corrosion resistance properties of the stainless steel layer of the laminate. The composite strip material is then readily formed into two, concentrically disposed convolutions of the strip material while the laminate material is in this highly formable condition. The convolutions of the strip material are then brazed together to provide a double-walled tubing, the brazing procedure being regulated to effect selected heat treatment of the formed composite material for substantially restoring the corrosion resistance properties of the stainless steel layer of the laminate within the finished tubing.
Abstract:
A manually set magnetic relay is utilized to override an electrical interlock in a one-time operation. Once the relay has been utilized, it automatically disables itself and must be manually set again for another operation. The relay includes an electromagnetic coil which closes a load switch connected in parallel with the electrical interlock. A secondary circuit for energizing the coil includes a second switch formed by a pair of flexible conductors at least one being flexible. A flexible latch engages one of the conductors of the second switch as the coil is energized and closes the load switch. The latch continues to hold the second switch in the latched and open condition when the coil is de-energized. To close the second switch and make energization of the coil possible, a manually actuated plunger engages the flexible latch and displaces it away from the one of the flexible conductors which then moves from the latched position to a position in contact with the other conductor of the second switch. The plunger also holds the load switch open during the unlatching operation to provide trip-free operation of the relay.
Abstract:
A monopulse direction finding receiver/processor system is described utilizing a three dimensional conformal antenna array, such as a circular cylindrical array, which generates a broad elevation, narrow azimuth beam therefrom. Both even and odd excitations are applied to the aperture of the antenna to simultaneously generate a monopulse pair of patterns. The azimuth complex sum ( Sigma ) and difference ( Delta ) returns from the array antenna are coupled to a phase/amplitude receiver which incorporates parallel receiver channels. The output from the phase/amplitude receiver produces a signal on each channel, one related to the ratio of the magnitude of Delta and Sigma , (namely Delta / Sigma ) and the other channel related to the phase diference between Delta and Sigma (namely