Abstract: A high dose rate, high impedance plasma ion implantation method and apparatus to apply high voltage pulses to a target cathode within an ionization chamber to both sustain a plasma in the gas surrounding the target, and to implant ions from the plasma into the target during at least a portion of each pulse. Operating at voltages in excess of 50 kV that are too high for the reliable formation of a conventional glow discharge, the plasma is instead sustained through a beam-plasma instability interaction between secondary electrons emitted from the target and a background pulsed plasma. The voltage pulses are at least about 50 kV, and preferably 100 kV or more. Pulse durations are preferably less than 8 microseconds, with a frequency in the 50-1,000 Hz range. The preferred gas pressure range is 1.times.10.sup.-4 -1.times.10.sup.

Abstract: A plasma switch is provided which can limit fault currents to a range that is elecrostatically interruptible by a control grid. The switch includes magnets that generate a first magnetic vector which cooperates with an electric field to generate a plasma, the density of which is a function of the magnitude of the first magnetic vector. A stalling coil is arranged to generate a second magnetic vector that opposes and cancels a portion of the first magnetic vector in response to a fault current through the switch. This establishes a stalling condition in which the plasma density falls and a plasma potential gradient is set up in the switch. In this unstable condition, the plasma current is interruptible by the control grid.

Abstract: Plasma-cathode electron gun structures capable of operation in low-pressure, e.g., <5.times.10.sup.-3 Torr, ionizable gas environments are disclosed. They utilize a thermionic emitter within an enclosure with a partially transparent electrode defining a plasma face. Spaced anodes are disposed adjacent the electrode to extract an electron beam from the plasma face. A magnetic system forms an inward directed field, and a portion of the plasma electrons are directed through this field to enhance ionization efficiency.

Abstract: A CROSSATRON plasma switch has a peak current capability in excess of 10kA and a switching speed of at least 1.times.10.sup.11 A/sec, making it compatible with the requirements of excimer and CO.sub.2 gas laser switches, and yet is small enough to be mechanically integrated with such lasers. It employs an axially corrugated cathode with a body diameter on the order of 10 cm and shallow corrugations whose depths are about 1.0-1.5 times the distance between corrugations, together with a reduced diameter anode (of about 2.5 cm diameter for an excimer laser and about 1.25 cm diameter for a CO.sub.2 laser), to obtain a plasma volume of about 50-100 cm.sup.3 for rapid switching. A magnet assembly around the cathode uses only two stacked magnets, but has an overall greater axial length and surface magnetic strength than in prior switches. The magnet design produces a high field strength near the cathode, but without a significant extension of the field into the anode region.

Abstract: A high dose rate, high impedance plasma ion implantation method and apparatus to apply high voltage pulses to a target cathode within an ionization chamber to both sustain a plasma in the gas surrounding the target, and to implant ions from the plasma into the target during at least a portion of each pulse. Operating at voltages in excess of 50 kV that are too high for the reliable formation of a conventional glow discharge, the plasma is instead sustained through a beam-plasma instability interaction between secondary electrons emitted from the target and a background pulsed plasma. The voltage pulses are at least about 50 kV, and preferably 100 kV or more. Pulse durations are preferably less than 8 microseconds, with a frequency in the 50-1,000 Hz range. The preferred gas pressure range is 1.times.10.sup.-4 -1.times.10.sup.

Abstract: A CROSSATRON switch is capable of operating with voltages in excess of 100 kV by the use of a deuterium gas fill to increase the Paschen breakdown voltage, axial molybdenum cathode corrugations to provide a higher current capability, and a Paschen shield that is formed from molybdenum. The terminal curvature of the Paschen shield and of the adjacent portion of the anode are selected to establish a voltage stress at the curved Paschen shield surface within the approximate range of 90-150 kV/cm in response to a 100 kV differential.

Abstract: An object which is to be implemented with ions is enclosed in a container. A plasma is generated in a chamber which is separate from, and opens into the container. The plasma diffuses from the chamber into the container to surround the object with uniform density. High voltage negative pulses are applied to the object, causing the ions to be accelerated from the plasma toward, and be implanted into, the object. Line-of-sight communication between a plasma generation source located in the chamber and the object is blocked, thereby eliminating undesirable effects including heating of the object by the source and transfer of thermally discharged material from the source to the object. Two or more chambers may be provided for generating independent plasmas of different ion species which diffuse into and uniformly mix in the container. The attributes of the different plasmas may be individually selected and controlled in the respective chambers.

Abstract: An object (14) which is to be implanted with ions is enclosed in a container (12). A plasma (44) is generated in a chamber (26) which is separate from, and opens into the container (12). The plasma diffuses from the chamber (26) into the container (12) to surround the object (14) with uniform density. High voltage negative pulses are applied to the object (14), causing the ions to be accelerated from the plasma (44) toward, and be implanted into, the object (14). Line-of-sight communication between a plasma generation source (30) located in the chamber (26) and the object (14) is blocked, thereby eliminating undesirable effects including heating of the object (14) by the source (30) and transfer of thermally discharged material from the source (30) to the object (14). Two or more chambers (26,34) may be provided for generating independent plasmas (44,46) of different ion species which diffuse into and uniformly mix in the container (12).

Abstract: A capacitor is charged to a high potential or voltage from a power source. A plasma switch, preferably a CROSSATRON modulator switch, is periodically closed and opened to discharge the capacitor into an object for implantation with ions from a plasma in a plasma source ion implantation apparatus. The periodic discharge results in the application of high voltage negative pulses to the object, causing ions from the plasma to be accelerated toward, and implanted into the object. A pulse transformer is preferably provided between the plasma switch and capacitor, and the object to step up the voltage of the pulses and enable the plasma switch to operate at lower voltage levels. The plasma switch enables high duty factor and power operation, and may be combined with arc detection and suppression circuitry to prevent arcing between the object and plasma.

Abstract: A diverging magnetic field is established between the cathode and control electrode of a hollow cathode plasma switch to expand the plasma at a passageway through the control electrode, thus significantly increasing the switch's current handling capability. Preferred ranges of magnetic field strength, gas pressure, spacing between the hollow cathode and control electrode, and the mesh aperture size for the control grid are described.

Abstract: An apparatus to apply materials to a substrate disposed in a vacuum chamber is disclosed. A separate generator chamber containing an electron emitter is connected to the vacuum chamber by a process chamber so that a plasma of controllable cross-sectional shape and large area is formed and guided by magnets toward a target system. Positive ions may be accelerated against the target by applying an adjustable negative voltage.

Abstract: A lanthanum hexaboride element, typically of cylindrical configuration, is mounted within a high plasma density cathode enclosure. An inlet is provided to supply gas to the cathode enclosure in the vicinity of the lanthanum hexaboride cathode element, and the element is heated to electron-emitting temperature. A plasma utilization chamber is coupled to receive an electron or plasma stream from the cathode enclosure through an aperture of a suitable size to maintain a relatively high plasma density within the cathode enclosure. The plasma density within the cathode enclosure is preferably above the critical level required for high current emission from the lanthanum hexaboride cathode structure. For example this may be in the order of 3.5 times 10.sup.12 electrons per cubic centimeter for a current density of 10 amperes per square centimeter. The lanthanum hexaboride cathode element is supported on notched graphite rings, and the cathode enclosure is made of tungsten.