Patent ID: 8110799

Claim:
A method of scanning electron beam imaging, the method comprising: generating electrons from an electron source; forming an incident electron beam from the generated electrons; controllably deflecting the incident electron beam in a time-dependent manner so as to cause scanning of a beam spot over an area of a substrate surface; focusing the incident electron beam onto the beam spot on the substrate surface, wherein impingement of the incident electron beam onto the substrate surface causes secondary electrons to be emitted from a region surrounding and including the beam spot; focusing the secondary electrons by a collection electron lens so as to form a secondary electron beam which is focused at a conjugate focal plane; controllably deflecting the secondary electrons so as to counteract an influence of said scanning such that a center portion of the secondary electron beam passes through a pin-hole filter positioned at the conjugate focal plane and a remainder portion of the secondary electron beam is filtered out by the filter; and detecting the portion of the secondary electron beam which passes through the pin-hole filter.