Method of and apparatus for detecting foreign substances
AssigneeHitachi, Ltd.
InventorsMitsuyoshi Koizumi, Yoshimasa Ohshima, Minoru Tanaka
Life of this patent
Estimating the term…
Abstract
The present invention provides a method for detecting foreign substances which detects a foreign substance with a first photoelectric conversion element by emphasizing the foreign substance and detects a background on the object with a second photoelectric conversion element by emphasizing the background and detects a foreign substance detection signal obtained from the first photoelectric conversion element by emphasizing the signal with a detection signal obtained from the second photoelectric conversion element.
Claims9
A method for detecting foreign substances on a patterned-background on an object, comprising the steps of:
- illuminating a surface of the object with at least a linear polarized laser beam at an angle inclined with respect to the surface of the object;
- detecting the foreign substance with a first photoelectric conversion element providing an output indicative of scattered light from the foreign substance;
- detecting the patterned-background on the object with a second photoelectric conversion element providing an output indicative of light reflected from an edge of the patterned-background;
- forming a foreign substance indicating signal by non-additively processing the output of the first and second photoelectric conversion elements;
- and
- detecting the foreign substance in accordance with the foreign substance indicating signal.
A method for detecting foreign substances on a patterned-background on an object, comprising the steps of:
- illuminating at least a surface of the object with a linear polarized laser beam at an angle inclined with respect to the surface of the object;
- optically converging a scattered light from the surface of the object with an object lens;
- scanning by effecting relative movement between the object and the object lens;
- transmitting a scattered light of the foreign substance from the scattered light without transmitting reflected light from an edge of the patterned-background utilizing an analyzer having a transmission axis parallel to a direction of the laser beam illumination;
- detecting the foreign substance on the object utilizing a semiconductor solid pickup element array arranged in a line transverse to a movement direction of the scanning;
- and
- detecting the foreign substance in accordance with a foreign substance detection signal obtained from the semiconductor solid pickup element array.
An apparatus for detecting foreign substances on a patterned-background on an object, comprising:
- means for illuminating a surface of the object with at least a linear polarized laser beam at an angle inclined with respect to the surface of the object;
- first detecting means for detecting the foreign substance on the ojbect with a first photoelectric conversion element for providing an output indicative of scattered light from the foreign substance, the first detecting means detecting the patterned-background on the object with a second photoelectric conversion element for providing an output indicative of light reflected from an edge of the patterned-background;
- means for forming a foreign substance indicating signal by non-additively processing the outputs of the first and second photoelectric conversion elements;
- and
- means for detecting the foreign substance in accordance with the foreign substance indicating signal.
An apparatus for detecting foreign substances on a patterned-background on an object, comprising:
- means for illuminating a surface of the object with at least a linear polarized laser beam at an angle inclined with respect to the surface of the object;
- converging means including an object lens for optically converging a scattered light from the surface of the object;
- scanning means for effecting relative movement between the object and the object lens;
- analyzing means for transmitting a scattered light of the foreign substance from the scattered light from the object without transmitting reflected light from an edge of the patterned-background, the analyzer means having a transmission axis parallel to a direction of the laser illumination;
- a semiconductor solid pickup element array responsive to the analyzer means for detecting the scattered light of the foreign substance, the semiconductor solid pickup element array being aranged in a line transverse to a moving direction of the scanning means;
- and
- means for detecting the foreign substance by a foreign substance signal obtained from the semiconductor solid pickup element array.
Dependencies are inferred from the claim text.