US 4,966,457 A · Inspecting apparatus for determining presence and location of foreign particles on reticles or pellicles

Abstract

A defect inspecting apparatus for determining the presence of a defect element adhering to either of the front and back surfaces of a thin film-like object to be inspected (the object having a light-transmitting property) applies two light beams of different wavelengths to a surface of the object and varies the incident angle of the light beams. A first photoelectric detector receives light of the two light beams reflected by or transmitted by the object, and a second photoelectric detector receives light of the two light beams scattered by the defect element. A discriminator determines the surface of the object to which the defect element adheres based on detection outputs of the photoelectric detectors.

Claims13

Dependent claims

A defect inspecting apparatus for determining the presence of a defect element adhering to either of the front and back surfaces of a thin film-like object to be inspected having a light-transmitting property, comprising:

applying means for applying two light beams of different wavelengths to one surface of said object to be inspected along an optical path leading to said object;
incident angle varying means for varying the incident angle of said two light beams onto said one surface;
first photoelectric detector means for receiving light of said two light beams reflected by or transmitted by said object to be inspected;
second photoelectric detector means for receiving light of said two light beams scattered by said defect element;
and discriminating means for discriminating the surface of said object to be inspected to which said defect element adheres on the basis of a detection output of said first photoelectric detector means and a detection output of said second photoelectric detector means.

2 more elements

a pair of laser sources emitting light beams of different wavelengths, respectively, light beam switching means for alternately selecting said two light beams of different wavelengths, applying means for obliquely applying each light beam selected by said light beam switching means to a position on one surface of said object to be inspected at a predetermined angle;
photoelectric detector means for receiving light of each selected light beam scattered by said defect element, driving means for displacing said photoelectric detector means angularly about said position on said object to be inspected;
and discriminating means for discriminating the surface of said object to be inspected to which said deflect element adheres on the basis of two detection outputs of said photoelectric detector means produced in response to the alternate reception of scattered light of said two light beams of different wavelengths.

Dependencies are inferred from the claim text.

Inspecting apparatus for determining presence and location of foreign particles on reticles or pellicles

Life of this patent

Inspecting apparatus for determining presence and location of foreign particles on reticles or pellicles

Life of this patent

Abstract

Claims13