Back to results
US 9,804,087 B2Granted
Hemispherical scanning optical scatterometer
AssigneeScatterMaster LLC
InventorsEric Loren Hegstrom, John Clyde Stover
Life of this patent
Estimating the term…
Abstract
A hemispherical scanning optical scatterometer and method for its use for measuring scattered radiation, with a reflected scatter measurement laser, and/or a transmitted scatter measurement laser, an array of optical detectors, a computer controlled system to rotate the array of optical detectors, an electronic system, a computer interface and a computer for processing the signal.
Claims20
A hemispherical scanning optical scatterometer for measuring scattered radiation, the scatterometer comprising:
- one or more scatter measurement lasers, located on one or more source arms and directing laser light at a sample at one or more incident angles;
- an array of optical detectors located on a measurement arm and measuring an intensity of a signal from the laser light scattered by the sample in either reflectance or transmission;
- a first computer controlled system to rotate the source arm or arms through a complete or partial sphere about an axis horizontal to the sample;
- a second computer controlled system to rotate the measurement arm of optical detectors on fixed paths about the axis horizontal to the sample so that a specular beam and a complete scattering hemisphere can be adequately sampled, with the optical detectors remaining perpendicular to scattered rays being measured through an entire hemispherical scan, with the source arm rotating in a same direction as the measurement arm and with the source arm rotating through a larger radius than the measurement arm;
- electronic systems for signal processing of each optical detector that include amplification and/or logarithmic conversion;
- a computer interface for conversion of the signal from analog to digital form;
- and
- a computer for processing the signal.
5 more elements
A method for measuring scattered radiation with a hemispherical scanning optical scatterometer, comprising:
- directing one or more lasers at a sample at one or more incident angles from a scatter measurement laser located on one or more source arms, rotating through a complete or partial sphere, about an axis horizontal to the sample;
- measuring intensities of the laser light scattered by the sample in either reflectance or transmission with an array of optical detectors located on a measurement arm;
- rotating the array of optical detectors on fixed paths about the axis horizontal to the sample with a first computer controlled system so that a specular beam and a complete scattering hemisphere can be adequately sampled, rotating the optical detectors perpendicular to scattered rays being measured through an entire hemispherical scan, rotating the source arm in a same direction as the measurement arm and rotating the source arm through a larger radius than the measurement arm;
- rotating the scatter measurement laser or lasers with a second computer controlled system through a plurality of incident angles;
- measuring repeatedly at the plurality of incident angles;
- performing processing of the signals from the detectors that include logarithmic conversion and/or amplification with an electronic system;
- converting the signal from analog to digital form with a computer interface;
- and
- processing the signal with a computer.
6 more elements
Dependencies are inferred from the claim text.