Kevin J Rhoads

US Patent:

6377039, Apr 23, 2002

Filed:

Nov 13, 1998

Appl. No.:

09/191668

Inventors:

Neil J. Goldfine - Newton MA
Kevin G. Rhoads - Andover MA
Karen E. Walrath - Arlington MA
David C. Clark - Arlington MA

Assignee:

Jentek Sensors, Incorporated - Waltham MA

International Classification:

G01N 2772

US Classification:

324232, 32420717, 324227, 324230, 324233, 324239

Abstract:

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.

US Patent:

7166853, Jan 23, 2007

Filed:

Sep 11, 2002

Appl. No.:

10/241307

Inventors:

Kevin G. Rhoads - Andover MA, US

Assignee:

Varian Semiconductor Equipment Associates, Inc. - Gloucester MA

International Classification:

G05F 3/04

US Classification:

25049221, 323355, 323305, 118723 R, 257357, 257355, 257356, 438212, 438223

Abstract:

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.

US Patent:

20020114124, Aug 22, 2002

Filed:

Nov 2, 2001

Appl. No.:

10/001025

Inventors:

Kevin Rhoads - Andover MA, US
Grant Larsen - Gloucester MA, US

Assignee:

Varian Semiconductor Equipment Associates, Inc.

International Classification:

H01H001/00

US Classification:

361/234000

Abstract:

A method for electrostatic clamping of a high resistivity workpiece includes the steps of positioning a high resistivity workpiece on a clamping surface of an electrostatic clamp, the electrostatic clamp including electrodes underlying and electrically isolated from the clamping surface, and applying AC clamping voltages to the electrodes for electrostatically clamping the workpiece in a fixed position on the clamping surface. The AC clamping voltages have a frequency in a range of about 0.00175 Hz to 10 Hz and more preferably have a frequency in a range of about 1 Hz to 6 Hz.

US Patent:

54898498, Feb 6, 1996

Filed:

Mar 14, 1994

Appl. No.:

8/212478

Inventors:

Donald R. Sadoway - Belmont MA
Kevin G. Rhoads - Andover MA
Naomi A. Fried - Cambridge MA
Susan L. Schiefelbein - Boston MA

Assignee:

Massachusetts Institute of Technology - Cambridge MA

International Classification:

G01N 2702

US Classification:

324447

Abstract:

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.

US Patent:

55107702, Apr 23, 1996

Filed:

Mar 30, 1994

Appl. No.:

8/220089

Inventors:

Kevin G. Rhoads - Andover MA

Assignee:

Checkpoint Systems, Inc. - Thorofare NJ

International Classification:

G08B 13187

US Classification:

340572

Abstract:

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.