Massachusetts Institute of Technology

Varian Semiconductor Equipment Associates, Inc.

Checkpoint Systems, Inc.

Jentek Sensors, Incorporated

Kevin G Rhoads

Neil J Goldfine

Donald Robert Sadoway

Karen E Walrath

David C Clark

Naomi A Fried

Susan L Schiefelbein

A system for electrically contacting a semiconductor wafer during implanting of the wafer includes one or more pairs of closely spaced contacts located adjacent the semiconductor wafer and a driving circuit connected to the contacts to provide a discharge from one contact to the semiconductor wafer and from the semiconductor wafer to the other contact of each pair of contacts. The contacts can be spaced apart from the wafer and the tips of the contacts closest to the wafer may have sharp points to aid in the establishment of corona at lower drive voltages. Alternately, the contacts may be rounded and may contact the wafer. The driving circuit may be adapted from a pulsed discharge circuit, such as a Kettering ignition circuit, a capacitance discharge ignition circuit, or a blocking oscillator circuit. Alternately, the driving circuit may be adapted from a continuous discharge circuit, such as a Tesla coil circuit.

Active method and system of establishing electrical contact

A system for characterizing coatings and substrates of a material under test. A sensor is positioned against a coated sample which is to be measured to obtain phase and magnitude measurements. Penetration depth of the magnetic waves of the sensor is a function of frequency. Measurements are made at each of a plurality of signal frequencies. The measured phase and magnitude data is applied with respect to a frequency independent parameter, such as conductivity, using a grid method. The conductivities of the coating and the substrate are determined by the limits of conductivity with respect to frequency. With the assumed conductivities of the coating and substrate, the sensor is once again placed over the material, and coating thickness and lift-off are determined. By examining the coating thickness versus frequency the accuracy of the measurement can be determined, since actual coating thickness does not vary with frequency in the material. Through iterative approximations, conductivity can then be accurately determined.

Method for characterizing coating and substrates

A security tag used with an electronic security system comprises a dielectric substrate having first and second opposite principal surfaces and a resonant circuit capable of resonating at a frequency within a detection frequency range. The resonant circuit is formed, in part, by a first conductive area on the first substrate surface and a second conductive area on the second substrate surface, the two conductive areas being generally aligned with one another to establish a capacitor with the substrate therebetween forming the capacitor dielectric. A third conductive area is provided on one of the principal substrate surfaces proximate to but not electrically connected to one of the two capacitor plates. The third conductive area is electrically connected to the other capacitor plate. A portion of the third conductive area is spaced from a portion of the one capacitor plate by a predetermined minimum distance whereby upon the application of electromagnetic energy to the tag at a frequency generally corresponding to the resonant frequency of the resonant circuit and at or above a predetermined minimum energy level, an electric arc extends between the spaced portions of the third conductive area and the one capacitor plate creating a persistent conductive bridge which connects the two plates of the capacitor in a short circuit.

Surface deactivateable tag

An apparatus and method for measuring electrical parameters of a medium such as electrical conductivity and dielectric constant between a pair of electrodes are disclosed. The medium can be a liquid, gas, powder, etc., and the electrodes can be coaxial metallic circular cylinders. To compute electrical conductivity, the device is immersed in the medium to an immersion depth and the conductance across the electrodes is determined. The measurement is repeated at at least one additional immersion depth. By obtaining a differential conductance measurement with respect to the immersion depth, the effects of fringe conductances are eliminated from the measurement. The device can also be used to determine dielectric constant of the material by obtaining a differential capacitance measurement with respect to immersion depth. The device need not be calibrated by performing resistance measurements in a known standard solution. Also, because the electrodes can be purely metallic and include no dielectric material, the device can be used to perform measurements in highly corrosive media whose compositions would be altered upon contact with dielectric materials.

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Andover, MA, United States of America

Kevin G Rhoads