Abstract: A technique for removing particles from above a semiconductor wafer, particularly particles that are trapped in a plasma chamber during processing of the wafer. Trapped particles are usually not all drawn out with gases exhausted from the chamber, in part because a peripheral focus ring and clamping mechanism impede their flow. In the method of the invention, the focus ring and clamping mechanism are raised on completion of processing, but before radio-frequency (rf) power is disconnected from the process chamber. Trapped particles are then easily flowed from the chamber with an introduced inert gas, and the level of particulate contamination of the wafer is significantly reduced.

Abstract: A method for reducing targeting errors encountered when trying to locate contaminant particles in a high-magnification imaging device, based on estimates of the particle positions obtained from a scanning device. The method of the invention includes scanning a semiconductor wafer in a scanning device, then preferably moving the wafer to a different orientation, and scanning the wafer again, to obtain at least two sets of particle coordinates that may differ slightly because of uncertainties in the scanning process. The multiple sets of coordinates are averaged to reduce the targeting errors, but only after transforming the coordinates to a common coordinate system. The transformation step includes computing transformation parameters for each possible pair of particles detected in at least two scans, averaging the results, and then transforming all of the particle coordinates to the common coordinate system.

Abstract: An improved method of etching or cleaning a cold-wall chemical vapor deposition chamber that is substantially moisture-free at a low chamber temperature and a low chamber pressure while maintaining a satisfactory etch rate by using at least one etchant gas selected from the group consisting of nitrogen trifluoride, chlorine trifluoride, sulfur hexafluoride, carbon tetrafluoride or the like and mixtures thereof.

Abstract: A thermal reaction chamber for semiconductor wafer processing operations comprising:(i) a susceptor for supporting a semiconductor wafer within the chamber and having a plurality of apertures formed vertically therethrough;(ii) displacer means for displacing the susceptor vertically between at least a first and a second position;(iii) a plurality of wafer support elements, each of which is suspended to be vertically moveable within said apertures and each of which extends beyond the underside of the susceptor; and(iv) means for restricting the downward movement of the wafer support elements. As the susceptor is displaced from its first position through an intermediate position before the second position, the means for restricting operate to stop the continued downward movement of the wafer support elements thereby causing the elements to move vertically upwards with respect to the downwardly moving susceptor and separate the wafer from the susceptor.

Abstract: An impregnated cathode comprising three layers: a very thin emitting surface layer of metal such as an alloy of tungsten with a high fraction of an activating metal of the platinum group to provide low workfunction; an underlying, thin buffer layer of porous tungsten alloyed with a fraction of activating metal, to retard diffusion loss of activating metal from the emitting layer; and a substrate of porous tungsten impregnated with barium aluminate.

Abstract: A process and apparatus is disclosed for providing access to the interior of a vacuum deposition chamber in a vacuum deposition apparatus without exposing residues, such as chlorosilane residues, within the chamber to moisture and/or oxygen-containing gases. The process comprises first placing over the upper surface of the vacuum deposition apparatus an enclosure which has a bottom opening large enough to completely cover the top opening to the chamber, and which is capable of being filled with one or more non-reactive gases. One or more non-reactive gases are then flowed into the enclosure to purge moisture and/or oxygen-containing gases from the enclosure. After the enclosure has been mounted on the apparatus and purged by the flow of non-reactive gases therein, the vacuum deposition chamber may be opened, while continuing the flow of non-reactive gases into the enclosure.

Abstract: Particles are repelled from the upper face of a wafer in a plasma chamber by inducing positive or negative charges on the substrate without generating a gas plasma above the substrate. The charges are induced in the substrate by bringing a conductive sheet carrying a DC voltage close to the underside of the substrate. The particle repelling effect may be enhanced by inducing alternating positive and negative charges in the substrate. This can be done by switching the polarity of the DC voltage applied to the conductive sheet, or alternatively by moving an actuator to repetitively ground and isolate the substrate from the chamber.

Abstract: In a chemical-vapor-deposition system, a method of reducing particulate contamination within a reaction chamber. In general, the chemical-vapor-deposition system contains a gas inlet conduit which connects a reaction chamber to a reactive gas source and a gas outlet conduit which connects the reaction chamber to a vacuum pump. The vacuum pump facilitates exhausting gas from the reaction chamber. The method of reducing particulate contamination in the system includes the steps of: filling, via said inlet conduit, the reaction chamber with a reactive gas; exhausting the reactive gas from the reaction chamber using the vacuum pump; isolating the reaction chamber from the vacuum pump to cease exhausting the chamber; backfilling, via the inlet conduit, the reaction chamber with the reactive gas; and preventing, during the backfilling step, generation of eddy currents in a portion of the outlet conduit by providing a particle restrictor within the outlet conduit.

Abstract: A micro-environment load lock for coupling a SMIF-type box containing a stack of semiconductor wafers directly to a wafer processing chamber includes a load lock chamber in communication with at least one wafer processing tool. The load lock also includes a seal operable to accept and sealably couple a SMIF-type box to the load lock chamber such that SMIF-type box becomes an extension of the load lock chamber, and provides a base that is selectably operable to open and close the SMIF-type box and to selectably draw a cassette of wafers from the SMIF-type box through a port in communication with the load lock chamber and into the load lock chamber. The base is also operable to seal the port in the absence of a SMIF-type box. A single robot is provided in conjunction with the load lock chamber for moving one wafer at a time between the cassette of wafers and the process chamber.

Abstract: Disclosed is a method for improving the dynamic resolution of an imaging system. The method employs a dual sampling or exposure technique which samples light from an image intensifier over a long and a short sample interval. When the resulting measurement for the long sample interval exceeds a threshold level, the short sample interval measurement is used, multiplied by a scaling factor. Below the threshold the long sample interval is used.

Abstract: The detector of the present invention is suitable for use in a radiation therapy simulator machine. The detector comprises an X-ray image intensifier tube to convert X-rays into photons, a linear array of photodiodes to convert the photons to electrical signals, optical means for coupling the photons to the linear array of photodiodes, and electronic signal processing means for conditioning the signals from the photodiodes. The conditioning includes the use of low noise, phaselocked sampling electronics, implementation of a dual sampling technique for increasing dynamic range, implementation of a linearizing technique for increasing the accuracy of the measurements, and implementation of techniques for adjusting the measurements for point spread and background noise effects.

Abstract: A receiver protector device includes a sealed discharge chamber containing one or more pairs of spaced-apart, conical electrodes and an ionizable gas. A field emission array is mounted in the discharge chamber to provide a source of free electrons which assist in initiating a discharge when an RF input signal exceeds a desired threshold power level. The field emission array includes a substrate, a plurality of generally conical emitters distributed on the substrate, a conductive gate layer for extracting electrons from the emitters and a dielectric layer between the gate layer and the substrate. When a bias voltage is applied to the gate layer, electrons are extracted from the emitters. The field emission array can be mounted adjacent to the electrodes or in a recess in one of the electrodes. The bias voltage can be supplied by a battery mounted on the receiver protector device external to the discharge chamber.

Abstract: A method for producing an ion beam for ion implantation by chemically enhanced bombardment of solids. The method is carried out in a reaction chamber having an anode and cathode and a cathode liner rich in a selected element, namely boron, arsenic, phosphorus or antimony. A non-poisonous feed gas is introduced into the reaction chamber and energy is supplied to the feed gas to generate a plasma in the reaction chamber. The constituents of the plasma react chemically with the selected element in the cathode liner and an electrical potential is established between the anode and the cathode so that ions in the plasma bombard the cathode liner. The chemical reaction and bombardment together generate an ion species in the plasma containing the selected element. A beam of ions containing the selected species is then extracted from the plasma.

Abstract: An improved electroinjection method of introducing a sample having positive and negative ions into a capillary column for CE or CZE process by introducing a short plug of a low concentration buffer before introducing the sample into the column which results in increasing amount of charged ions of the sample introduced in the capillary column due to increasing the electric field at the injection point. A method for efficiently introducing both positive and negative ions is also shown.

Abstract: A photoionization detector for detecting effluents from a gas chromatographic column has a microwave induced helium plasma as the photon source. Since the source plasma may be at atmospheric pressure and need not be sealed, energy loss due to transmission of photons through a window can be eliminated. Use of alternating electromagnetic fields instead of a direct current discharge obviates the problems of anode sputtering.

Abstract: A spectroscopic plasma torch suitable for use at atmospheric pressure is disclosed. The torch utilizes a microwave induced helium plasma confined in a plasma discharge tube. The plasma is suspended and stabilized by a vortex flow of helium. The torch includes a high velocity gas jet for introducing sample materials into the plasma. The design avoids the formation of carbon deposits in the plasma discharge tube caused by the premature pyrolysis of organic materials outside the plasma and prevents other sample materials from being adsorbed on the surface of the plasma tube. Because of these characteristics, the torch is particularly well suited for use as a component in a gas chromatography detector which employs helium as the plasma support gas.

Abstract: A pulse forming network or capacitor load is charged to a precise voltage from an energy storing device with a circuit including a transformer having a primary connected in series with a switch and storage device and a secondary connected in series with the load and a monitor circuit. The monitor circuit develops an output signal indicative of the load voltage and current. In response to the output signal increasing to a predetermined value the switch is opened. The transformer, having a substantial leakage inductance, releases its stored energy when the switch is opened. The transformer stored energy is coupled to the load and to a capacitor connected to the primary. Charge stored in the capacitor after the load requirements have been satisfied is transferred back to the energy storage device.

Abstract: An apparatus and method for switching unpolarized light are provided. The apparatus includes GaInAs/GaAs optical switching devices which can be fabricated using conventional processes on a single wafer in matrix arrangement to provide an n.times.m cross bar switch. Switching is accomplished by shifting the band gap of the GaInAs material of a device using electrical or optical power to heat the material. Each switching device may comprise two-polarity (n/p) or single polarity (n or p) semiconductor materials.

Abstract: A band selector for a klystron includes a cam carrier and a plurality of cam followers. The cam carrier includes a plurality of cams with the cams being arranged in a plurality of rows. Each of the cam followers has a first end adapted to be mounted to a respective one of the plungers in the klystron and a second end. The cam carrier is positionable so that a selected one of the rows aligns with the cam followers. The cam followers are normally biased so that the second end of the cam followers abuts a respective one of the cams. The band selector further includes a first member movable between a first position and a second position. When the first member is in the first position, it is non-interactive with the cam followers. When the first member is moved to its second position, it becomes engageable with the first end of each of the cam followers to remove the second end of the cam followers from abutment with the respective one of the cams.

Abstract: A device for releaseably holding a workpiece includes a resilient collet which is attached to a base by an elastomeric member. Typically, the collet is an annular ring. Several fingers for holding the workpiece extend from the collet. The fingers are pivoted by actuating a member which elastically deforms the collet and causes the fingers to pivot from a position for engaging the workpiece to a position for releasing the workpiece and vice-versa. In one application, the base is a platen for supporting a wafer in a semiconductor processing system, and a plurality of the holding devices are arranged around the periphery of a rotating disk. A counterweight ring is attached to the collet to counterbalance the moment generated by the centrifugal force of the wafer pressing against the fingers as the disk is rotated.