Abstract: An integrated circuit is protected from reverse engineering by connecting doped circuit elements of like conductivity with a doped implant in the substrate, rather than with a metallized interconnect. The doped circuit elements and their corresponding implant interconnections can be formed in a common fabrication step with common implant masks, such that they have an integral structure with similar dopant concentrations. The metallization above the substrate surface can be designed to provide further masking of the interconnects, and microbridges can be added to span strips of transistor gate material in the interconnect path.

Abstract: A method and apparatus for protecting semiconductor integrated circuits from reverse engineering. Semiconductor active areas are formed on a substrate. A silicide layer is formed both over at least one active area of the semiconductor active areas and over a selected substrate area for interconnecting the at least one active area with another area through the silicide area formed on the selected substrate area. In a preferred embodiment a silicide layer formed on a first active area is interconnectingly merged laterally with a silicide layer formed on a second active area through the silicide layer formed on the selected substrate area.

Abstract: An integrated digital circuit is protected from reverse engineering by fabricating all transistors of like conductivity with a common size and geometric layout, providing a common layout for different logic cells, connecting doped circuit elements of like conductivity with electrically conductive doped implants in the substrate rather than metalized interconnections, and providing non-functional apparent interconnections that are interrupted by non-discernable channel stops so that all cells falsely appear to have a common interconnection scheme. The camouflage is enhanced by providing a uniform pattern of metal leads over the transistor array, with a uniform pattern of heavily doped implant taps from the transistors for connection to the leads; undesired tap-lead connections are blocked by channel stops.

Abstract: Connections between implanted regions in a semiconductor substrate, such as the sources or drains of adjacent transistors, are made by buried conductive implants rather than upper level metalizations. The presence or absence of a connection between two implanted regions is camouflaged by implanting a conductive buried layer of the same doping conductivity as the implanted regions when a connection is desired, and a field implant of opposite conductivity to the implanted regions when no connection is desired, and forming steps into the substrate at the boundaries of the buried layer or field implant that mask the steps formed between different conductivity regions during a selective etch by a reverse engineer. The masking steps are preferably formed by field oxide layers that terminate at the boundaries of the buried layers and field implants.

Abstract: An integrated digital circuit is protected from reverse engineering by fabricating all transistors of like conductivity with a common size and geometric layout, providing a common layout for different logic cells, connecting doped circuit elements of like conductivity with electrically conductive doped implants in the substrate rather than metalized interconnections, and providing non-functional apparent interconnections that are interrupted by non-discernable channel stops so that all cells falsely appear to have a common interconnection scheme. The camouflage is enhanced by providing a uniform pattern of metal leads over the transistor array, with a uniform pattern of heavily doped implant taps from the transistors for connection to the leads; undesired tap-lead connections are blocked by channel stops.

Abstract: A binary, boron-based alloy as a source for field-emission-type, ion-beam generating devices, wherein boron predominates in the alloy, preferably with a presence of about 60 atomic percent. The other constituent in the alloy is selected from the group of elements consisting of nickel, palladium and platinum. Predominance of boron in these alloys, during operation, promotes combining of boron with trace impurities of carbon in the alloys to form B.sub.4 C and thus to promote wetting of an associated carbon support substrate.

Abstract: An integrated circuit is protected from reverse engineering by connecting doped circuit elements of like conductivity with a doped implant in the substrate, rather than with a metallized interconnect. The doped circuit elements and their corresponding implant interconnections can be formed in a common fabrication step with common implant masks, such that they have an integral structure with similar dopant concentrations. The metallization above the substrate surface can be designed to provide further masking of the interconnects, and microbridges can be added to span strips of transistor gate material in the interconnect path.

Abstract: An integrated digital circuit is protected from reverse engineering by fabricating all transistors of like conductivity with a common size and geometric layout, providing a common layout for different logic cells, connecting doped circuit elements of like conductivity with electrically conductive doped implants in the substrate rather than metalized interconnections, and providing non-functional apparent interconnections that are interrupted by non-discernable channel stops so that all cells falsely appear to have a common interconnection scheme. The camouflage is enhanced by providing a uniform pattern of metal leads over the transistor array, with a uniform pattern of heavily doped implant taps from the transistors for connection to the leads; undesired tap-lead connections are blocked by channel stops.

Abstract: The present invention is a suspension unit having active and passive modes, for a vehicle suspension system, having a fluid source for providing a pressurized fluid. The suspension unit comprises a fluid actuator, a fluid spring, and fluid connecting means for coupling the fluid source to the fluid actuator. The suspension unit further includes mode selection means coupled to the fluid connecting means for responsively selecting the mode of the suspension unit, first valve means coupled to the mode selection means for providing fluid communication between the fluid spring and the fluid actuator in the active mode, and second valve means coupled to the fluid connecting means between the fluid spring and the fluid actuator in the active mode for providing fluid communication between the fluid spring and the fluid actuator in the passive mode.

Abstract: A high value, precision resistor (10) includes a doped region (18) having a boustrophedonic (folded or meandering) shape formed in a substrate (12). At least one section of the doped region (18) is formed by implantation using a focused ion beam. Where the entire doped region (18) is formed by the focused ion beam, the length thereof is selected to be large (10 to 100 times the width of the boustrophedonic shape) to maximize the accuracy of the resistor (10) by averaging over variations in grain size and implant dose. Alternatively, a probe resistor (32) and a plurality of similar unconnected doped sections (28) may be formed by means such as photolithography and flood ion implantation. The probe resistor (32) is measured at the desired operating temperature to determine the ratio of the measured resistance to the desired design resistance value.

Abstract: An ion evaporation source for tin ions is prepared by coating a source element with a wettability enhancing gallium coating, and then loading the source with tin. The tin may be the naturally occurring tin, but can be an enriched tin containing a higher concentration of Sn.sup.120. The source produces a beam having a high fraction of Sn.sup.+ and Sn.sup.++ ions, and a small amount of the ionized wettability coating material. All but the desired ions are readily separated from the beam.

Abstract: A charge-coupled device (CCD) is provided with a dopant implant gradient, lateral channel stops and blocking implants by means of a focused ion beam (FIB). The FIB is repeatedly scanned across each cell of the CCD as a succession of overlapping but discrete implant scans. The doping levels of the FIB implants accumulate to a stepwise approximation of a desired dopant density profile, the widths of the steps being no greater than about half the widths of the discrete FIB implants. With a FIB pixel of about 750-1,500 Angstroms, the widths of the steps are preferably about 250-500 Angstroms; the dimension of the cells in the dopant gradient direction can be made less than about 5 microns. The lateral channel stops and back blocking implants can be as narrow as single FIB pixel widths, thus freeing up more of the cell for charge carrying capacity.

Abstract: A liquid metal ion source and alloy, wherein the species to be emitted from the ion source is contained in a congruently vaporizing alloy. In one embodiment, the liquid metal ion source acts as a source of arsenic, and in a source alloy the arsenic is combined with palladium, preferably in a liquid alloy having a range of compositions from about 24 to about 33 atomic percent arsenic. Such an alloy may be readily prepared by a combustion synthesis technique. Liquid metal ion sources thus prepared produce arsenic ions for implantation, have long lifetimes, and are highly stable in operation.

Abstract: A process for enhancing the wettability of evaporation elements, such as substrates and metal reservoirs used in liquid metal ion sources, and the elements so produced wherein a coating material is wettably coated onto the evaporation element at a coating temperature greater than the ion source operating temperature. The coated element is cooled to the operating temperature, and then contacted with the molten ion source alloy. The coating material is selected to wet the substrate or reservoir at the coating temperature, but to be itself wet by the ion source alloy at the ion source operating temperature. The preferred coating metal is gold, which is first applied by electrodeposition onto the evaporation element, and the evaporation element and coating are heated to a coating temperature of about 800.degree. C. to complete the coating step. The coated evaporation element is cooled to the source operating temperature of 200.degree. C.-300.degree. C.

Abstract: A liquid metal ion source and alloy for the simultaneous ion evaporation of arsenic and boron, arsenic and phosphorus, or arsenic, boron and phosphorus. The ionic species to be evaporated are contained in palladium-arsenic-boron and palladium-arsenic-boron-phosphorus alloys. The ion source, including an emitter means such as a needle emitter and a source means such as U-shaped heater element, is preferably constructed of rhenium and tungsten, both of which are readily fabricated. The ion sources emit continuous beams of ions having sufficiently high currents of the desired species to be useful in ion implantation of semiconductor wafers for preparing integrated circuit devices. The sources are stable in operation, experience little corrosion during operation, and have long operating lifetimes.

Abstract: A liquid metal ion source alloy for high vapor pressure metalloids, wherein the alloy composition is chosen to have a low melting point so that the vapor pressure of the volatile constituents is low, even in the liquid state. Specifically, the ion source alloy is an alloy selected from the group of (Pb.sub.0.7-1.0 Au.sub.0.3-0).sub.0.7-0.99 (As+Sb).sub.0.3-0.01 and Pb.sub.0.20-0.30 Au.sub.0.45-0.55 (As+Sb).sub.0.20-0.30. The melting points of these alloys are about 200.degree. C.-300.degree. C., and the alloys may be maintained molten in contact with the emission elements for long periods of time without significant loss of the volatile species or reactivity with typical substrate materials used for emission elements.

Abstract: Two lens focused ion beam column (10) has an accelerating lens (20) which carries a potential to focus an image of the liquid metal ion source (14) on the mass analyzer slit (26) with a magnification of about unity. Munro lens (36) accelerates the beam of selected ion species and demagnifies the image through a long working distance to provide an ion writing spot of less than about 1000 .ANG. size.