Defect inspecting apparatus using multiple color light to detect defects
AssigneeNikon Corporation
InventorsFuminori Hayano, Sunao Murata
Life of this patent
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Abstract
A defect inspecting apparatus for discriminating one of two surfaces of a flat transparent object such as a pericle. The flat object is irradiated with a beam of light which is supplied from a light source and which is multiple-color light having predetermined wavelength ranges or white light of a broad band, scattered light from the defect is received by an optical element having wavelength selectivity, and scattered lights thereby separated with respect to the particular wavelength ranges are photoelectrically detected. The intensities of photoelectric signals thereby obtained are compared with each other.
Claims14
An apparatus for inspecting surfaces of a flat transparent object, comprising:
- means for directing multiple-color light having an intensity distribution through a predetermined wavelength range to one of the surfaces of the flat object to illuminate same;
- detection means for detecting scattered light produced by a defect existing on one of the surfaces of the flat object with respect to a plurality of different wavelength ranges, and for producing a plurality of outputs corresponding to the intensities of scattered light of the plurality of wavelength ranges;
- and
- means for discriminating the surface of the flat object on which the defect exists based on the comparison between the plurality of outputs from said detection means.
An apparatus for inspecting surfaces of a flat transparent object, comprising:
- irradiation means for directing multiple-color light having an intensity distribution through a predetermined wavelength range to one of the surfaces of the flat object to illuminate same;
- first detection means for detecting the quantities of multiple-color light from said illumination means with respect to a plurality of wavelength ranges and for producing corresponding outputs;
- second detection means for detecting the quantities of scattered light produced by a defect existing on one of the surfaces of the flat object with respect to a plurality of different wavelength ranges generally equal to the wavelength ranges with which said first detection means effects the detection, and for producing corresponding outputs;
- and
- comparison means for comparing the outputs from said first and second detection means with respect to the plurality of wavelength ranges.
An apparatus for inspecting surfaces of a flat transparent object, comprising:
- irradiation means for directing multiple-color light having an intensity distribution through a predetermined wavelength range to one of the surfaces of the flat object to illuminate same;
- a first light receiving system for receiving scattered light produced by a defect existing on one of the surfaces of the flat object in a direction at a predetermined angle to the surface of the flat object;
- a second light receiving system for receiving the scattered light in a direction at a angle to the surface of the flat object different from the angle at which said first light receiving system receives the scattered light;
- first detection means for detecting the quantity of scattered light received by said first light receiving system with respect to wavelength ranges according to predetermined spectral characteristics, and for outputting corresponding outputs;
- second detection means for detecting the quantity of scattered light received by said second light receiving system with respect to wavelength ranges according to substantially the same spectral characteristics as said first detection means;
- and
- comparison means for obtaining the ratio of the output from said first detection means and the output from said second detection means with respect to the plurality of wavelength ranges.
Dependencies are inferred from the claim text.