Method and apparatus for inspecting sample surface

Abstract

Provided is a method and an apparatus for inspecting a sample surface with high accuracy. Provided is a method for inspecting a sample surface by using an electron beam method sample surface inspection apparatus, in which an electron beam generated by an electron gun of the electron beam method sample surface inspection apparatus is irradiated onto the sample surface, and secondary electrons emanating from the sample surface are formed into an image toward an electron detection plane of a detector for inspecting the sample surface, the method characterized in that a condition for forming the secondary electrons into an image on a detection plane of the detector is controlled such that a potential in the sample surface varies in dependence on an amount of the electron beam irradiated onto the sample surface.

1 . A method for inspecting a sample surface by using a sample surface inspection apparatus, in which an electron beam generated by an electron gun of the sample surface inspection apparatus is irradiated onto the sample surface, and secondary electrons emanating from the sample surface are formed into an image toward an electron detection plane of a detector for inspecting the sample surface, the method characterized in that:
 a condition for forming the secondary electrons into an image on the detection plane of the detector is controlled such that a potential in the sample surface varies in dependence on an amount of the electron beam irradiated onto the sample surface.   
   
   
       2 . A method for inspecting a sample surface in accordance with  claim 1 , characterized in that a method for controlling the condition for forming the secondary electrons into an image is provided by modifying a sample voltage or a retarding voltage in dependence on an amount of the electron beam irradiated onto the sample surface. 
   
   
       3 . A method for inspecting a sample surface in accordance with  claim 1  or  2 , characterized in that the detector is an EB-CCD. 
   
   
       4 . A sample surface inspection apparatus, comprising: an electron gun for generating an electron beam to be irradiated onto a sample surface; a primary optical system for guiding the electron beam onto the sample surface; a detector for detecting secondary electrons emanating from the sample surface; and a secondary optical system for guiding the secondary electrons onto the detector, the apparatus characterized in further comprising a voltage adjustment mechanism for modifying a potential in the sample surface in dependence on an amount of the electron beam. 
   
   
       5 . A sample surface inspection apparatus in accordance with  claim 4 , characterized in that the voltage adjustment mechanism has a means for modifying a sample voltage or a retarding voltage in dependence on an amount of the electron beam irradiated onto the sample surface. 
   
   
       6 . A sample surface inspection apparatus in accordance with  claim 4  or  5  characterized in that the detector is an EB-CCD. 
   
   
       7 . An inspection method for inspecting a pattern formed in a sample by using an electron beam, the method characterized in that a stage holding a sample thereon is moved at a frequency in synchronism with an operating frequency of a sensor during inspection of a pattern to be inspected, and a moving speed of the stage is controlled so that a time required for movement is minimized during the stage being moved to another pattern to be inspected. 
   
   
       8 . An inspection method in accordance with  claim 7  characterized in that the pattern to be inspected includes two or more patterns consisting of different sectional structures or different materials, and a plurality of patterns are inspected concurrently. 
   
   
       9 . An inspection apparatus for inspecting a pattern formed in a sample by using an electron beam, characterized in comprising:
 a holding mechanism for holding the sample;   a stage with the holding mechanism mounted thereon and adapted to be movable in at least one direction;   an electron beam source for generating electrons for irradiation of the electron beam directed to the sample;   a first electro-optical system for guiding the electron beam generated from the electron beam source onto the sample for irradiation of the electron beam to the sample;   a detector for detecting electrons emanating from the sample;   a second electro-optical system for guiding the electrons to the detector; and   a control unit to provide a control so that the stage is moved at a speed in synchronism with an operating speed of the detector during inspection of the pattern, and the stage is accelerated when being moved to another pattern on the sample.   
   
   
       10 . An inspection apparatus in accordance with  claim 9 , characterized in that the pattern to be inspected includes two or more patterns consisting of different sectional structures or different materials, and a plurality of patterns are inspected concurrently. 
   
   
       11 . An inspection apparatus for inspecting a pattern formed on a sample by using an electron beam, characterized in comprising:
 a holding mechanism for holding the sample;   a stage with the holding mechanism mounted thereon and adapted to be movable in at least one direction;   an electron beam source for generating electrons for irradiation of the electron beam directed to the sample;   a first electro-optical system for guiding the electron beam generated from the electron beam source onto the sample for irradiation of the electron beam to the sample;   a detector for detecting electrons emanating from the sample; and   a second electro-optical system for guiding the electrons to the detector,   wherein an irradiation geometry of the electron beam to the pattern defines an elongated irradiation geometry that is longer than a length of the pattern along the moving direction of the stage during the stage being moved serially for inspecting the pattern so that the pattern could have been previously subject to the irradiation of electrons.   
   
   
       12 . An inspection apparatus for inspecting a pattern formed on a sample by using an electron beam, characterized in comprising:
 a holding mechanism for holding the sample;   a stage with the holding mechanism mounted thereon and adapted to be movable in at least one direction;   an electron beam source for generating electrons for irradiation of the electron beam directed to the sample;   a first electro-optical system for guiding the electron beam generated from the electron beam source onto the sample for irradiation of the electron beam to the sample;   a detector for detecting electrons emanating from the sample;   a second electro-optical system for guiding the electrons to the detector; and   a control unit for controlling an irradiation geometry of the electron beam in association with an operation of the stage so that the irradiation geometry of the electron beam onto the pattern allows the pattern to be previously subject to the irradiation of electrons during the stage being moved serially for inspecting the pattern.   
   
   
       13 . An inspection apparatus in accordance with  claim 11  or  12 , characterized in that the pattern to be inspected includes two or more patterns consisting of different sectional structures or different materials, and a plurality of patterns are inspected concurrently. 
   
   
       14 . An inspection method for inspecting a pattern on a sample while irradiating an electron beam onto the sample and moving the sample serially, the method characterized in that an irradiation area of the electron beam onto the pattern is controlled, for inspecting the pattern, to have a desired size so that a desired amount of the electron beam is irradiated to the pattern. 
   
   
       15 . An inspection method in accordance with  claim 14 , characterized in that the pattern includes two or more patterns consisting of different sectional structures or different materials, and a plurality of patterns are inspected concurrently.