David W Doerr

US Patent:

6864457, Mar 8, 2005

Filed:

Jan 21, 2003

Appl. No.:

10/347533

Inventors:

Dennis R. Alexander - Lincoln NE, US
Brian W. Milulka - Lincoln NE, US
David W. Doerr - Lincoln NE, US

Assignee:

The Board of Regents of the University of Nebraska - Lincoln NE

International Classification:

B23K015/00

US Classification:

21912111, 2191216

Abstract:

Disclosed are systems and methods for reducing the adverse effects of particles which become dislodged by scribing and laser machining of materials, which dislodged particles otherwise accumulate on laser machined material surfaces and cause adverse effects.

US Patent:

55045820, Apr 2, 1996

Filed:

Nov 14, 1994

Appl. No.:

8/339834

Inventors:

Blaine D. Johs - Lincoln NE
Shakil A. Pittal - Lincoln NE
Steven E. Green - Lincoln NE
John A. Woollam - Lincoln NE
David W. Doerr - Lincoln NE
Reed A. Christenson - Lincoln NE

Assignee:

J. A. Woollam Co. Inc. - Lincoln NE

International Classification:

G01N 2121

US Classification:

356369

Abstract:

An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a stationary compensator, positioned between an analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The use of a light fiber to carry light from a source thereof, to a polarization state generator, is also disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.

US Patent:

55217060, May 28, 1996

Filed:

Jun 24, 1994

Appl. No.:

8/265325

Inventors:

Steven E. Green - Lincoln NE
Shakil A. Pittal - Lincoln NE
Blaine D. Johs - Lincoln NE
John A. Woollam - Lincoln NE
David W. Doerr - Lincoln NE
Reed A. Christenson - Lincoln NE

Assignee:

J. A. Woollam Co. Inc. - Lincoln NE

International Classification:

G01N 2121

US Classification:

356369

Abstract:

An ellipsometer system which includes a pivotal dispersive optics positioned to receive polychromatic light from an analyzer thereof, without further focusing after reflection from a substrate system, is presented. In addition, a rotating compensator, positioned between the analyzer and the dispersive optics, which serves to reduce detector element polarization dependent sensitivity to light entering thereto after it interacts with the dispersive optics, is disclosed. The method of the present invention can include application of mathematical correction factors to, for instance, substrate system characterizing PSI and DELTA values, or Fourier ALPHA and BETA coefficients.

US Patent:

53733592, Dec 13, 1994

Filed:

Sep 18, 1992

Appl. No.:

7/947430

Inventors:

John A. Woollam - Lincoln NE
Blaine D. Johs - Lincoln NE
David W. Doerr - Lincoln NE
Reed A. Christenson - Lincoln NE

Assignee:

J. A. Woollam Co. - Lincoln NE

International Classification:

G01J 3447
G01N 2121

US Classification:

356328

Abstract:

To sense characteristics of a sample, an ellipsometer includes a pivotal diffraction grating positioned to receive white light from the analyzer without further focusing of the light after the light leaves the sample. The diffraction grating is focused on the sensor at a predetermined angle with a precision of at least plus or minus one-half degree using an alignment-sensing means positioned between the analyzer and diffraction grating. The sensor includes an aperture through which the incident beam of light is transmitted, light-sensitive areas on opposite sides of said sensor and a comparator for comparing the signal from said light-sensitive areas. Equality of the light from the light-sensitive areas indicates that the incident beam of light is perpendicular to the diffraction grating. A second diffraction grating and a second sensing means may receive the specularly reflected white light from a first diffraction grating and reflect it to another diffraction grating to investigate another spectrum of light. A spectroscopic ellipsometer uses a stacked photodiode in which the first photodiode and second photodiode have overlapping spectral ranges.