Method and Apparatus for Observing and Inspecting Defects

Abstract

A defect inspecting apparatus includes a sample mounting device for mounting a sample; lighting and detecting apparatus for illuminating a patterned sample mounted on a mount and detecting the optical image of the reflected light obtained therefrom. Also included is a display for displaying the optical image detected by this lighting and detecting apparatus; an optical parameter setting device for setting and displaying optical parameters for the lighting and detecting apparatus on the display; and optical parameter adjusting apparatus for adjusting optical parameters set for the lighting and detecting apparatus according to the optical parameters set by the optical parameter setting apparatus; a storage device for storing comparative image data; and a defect detecting device for detecting defects from patterns formed on the sample by comparing the optical image detected by the optical image detecting apparatus with the comparative image data stored in the storage.

1 . An apparatus for inspecting a specimen, comprising:
 an illuminating unit which perpendicularly illuminates a specimen with incident polarized ultraviolet light that emanates from an ultraviolet light source and passes through a polarizer and a lens;   a detecting unit having a sensor which detects light reflected from the specimen due to illumination of the specimen by the polarized ultraviolet light, the light reflected from the specimen passing through the lens and an analyzer; and   a signal processing unit which processes a signal produced by the detector due to detection of the light reflected from the specimen to detect defects on the specimen,   wherein a polarization state of the light reflected from the specimen is set so that a signal to noise ratio of a signal output of the sensor is increased.   
   
   
       2 . An apparatus according to  claim 1 , further comprising a polarized beam splitter which separates the optical path of the incident polarized ultraviolet light from the optical path of the light reflected from the specimen. 
   
   
       3 . An apparatus according to  claim 1 , wherein the polarizer is disposed in the optical path of ultraviolet light emanating from the ultraviolet light source, wherein the polarization state of the light detected by the detecting unit is variably arranged by the polarizer. 
   
   
       4 . An apparatus according to  claim 2 , wherein the analyzer is disposed in the optical path of the light reflected from the specimen which passes through the polarized beam splitter, wherein the polarization state of the light detected by the detecting unit is variably arranged by the analyzer. 
   
   
       5 . An apparatus for inspecting a specimen, comprising:
 an illuminating unit which perpendicularly illuminates a specimen with incident polarized ultraviolet light emanating from an ultraviolet light source and passing through a lens;   a detecting unit which detects light reflected from the specimen due to illumination thereof by the polarized light, the light reflected from the specimen passing through the lens; and   a signal processing unit which processes a signal output from the detector resulting from detection of the light reflected from the specimen to detect defects on the specimen,   wherein a polarization state of the light reflected from the specimen and detected by the detecting unit is so arranged that a defect detection sensitivity at the signal processing unit is increased.   
   
   
       6 . An apparatus according to  claim 5 , further comprising a polarized beam splitter which separates an optical path of the light reflected from the specimen by the illumination of the polarized ultraviolet light from an optical path of the incident polarized ultraviolet light. 
   
   
       7 . An apparatus according to  claim 5 , wherein the polarization state of the light is variably arranged by the polarizer, the polarizer being disposed in the an optical path of ultraviolet light emitted from the ultraviolet light source. 
   
   
       8 . An apparatus according to  claim 6 , wherein the polarization state of the light detected by the detecting unit is variably arranged by the analyzer, the analyzer being disposed in the optical path of the light reflected from the specimen and passing through the polarized beam splitter. 
   
   
       9 . A method of inspecting a specimen, comprising steps of:
 illuminating a specimen with a polarized ultraviolet light through a polarizer and a lens;   detecting with a detector light reflected from the specimen due to illumination by the polarized light and passing through the lens and an analyzer; and   processing a signal output from the detector resulting from detection of the reflected light by using a reference signal stored in a memory to detect a defect on the specimen,   wherein in the step of detecting, a polarization state of the light detected by the detector is so arranged by at least the polarizer or the analyzer such that a signal to noise ratio of a signal output from the detector is increased.   
   
   
       10 . A method according to  claim 9 , wherein the optical path of the light reflected from the specimen by the illumination of the polarized ultraviolet light is separated from the optical path of the polarized ultraviolet light illuminating the specimen by a polarized beam splitter. 
   
   
       11 . A method according to  claim 9 , wherein the polarization state of the light detected by the detector is variably arranged by the polarizer which is disposed in the optical path of the ultraviolet light illuminating the specimen. 
   
   
       12 . A method according to  claim 9 , wherein the polarization state of the light detected by the detector is variably arranged by the analyzer which is disposed in the optical path of the light reflected from the specimen and passed through the polarized beam splitter. 
   
   
       13 . A method according to  claim 11 , wherein in the step of illuminating the specimen is illuminated with elliptically polarized ultraviolet light. 
   
   
       14 . A method of inspecting a specimen, comprising steps of:
 illuminating a specimen with a polarized light through a polarizer and a lens;   detecting light reflected from the specimen by the illumination of the polarized light and passed through the lens and an analyzer with a detector; and   processing a signal output from the detector by the detection of the reflected light by using a reference signal stored in a memory to detect a defect on the specimen,   wherein in the step of detecting, a polarization state of the light detected by the detector is so arranged by the polarizer and/or the analyzer that a defect detection sensitivity at the signal processing unit is increased.   
   
   
       15 . A method according to  claim 14 , wherein an optical path of the light reflected from the specimen by the illumination of the polarized ultraviolet light is separated from an optical path of the polarized ultraviolet light illuminating the specimen by a polarized beam splitter. 
   
   
       16 . An apparatus according to  claim 14 , wherein said polarization state of the light detected by the detector is variably arranged by the polarizer set in an optical path of the ultraviolet light illuminating the specimen. 
   
   
       17 . An apparatus according to  claim 14 , wherein said polarization state of the light detected by the detecting unit is variably arranged by the analyzer set in an optical path of the light reflected from the specimen and passed through the polarized beam splitter. 
   
   
       18 . A method according to  claim 14 , wherein in the step of illuminating, said specimen is illuminated with an elliptically polarized ultraviolet light.