Patent ID: 6960766
Filing Date: 2005-11-01
Classification: H01J

Abstract:
1. An immersion lens system or focusing a primary particle beam and moving the focused primary particle beam on a specimen to be examined and collecting a plurality of secondary electrons and back-scattered electrons generated by the primary beam colliding with the specimen, the system comprising: a lens adapted to generate a magnetic field in a vicinity of the specimen to focus the particles of the particle beam on the specimen, the lens having a central bore through which the particle beam travels; an electrode having a potential adapted to provide a retarding field to the particle beam near and at the specimen to reduce an energy of the particle beam when the particle beam collides with the specimen; a deflection system including at least one deflection unit along a beam axis for deflecting the particle beam to allow scanning of the specimen, at least one deflection unit located in a retarding field of the beam, and at least one deflection unit located within the central bore of the lens; an annular detection unit within the central bore and located within a vicinity of where the primary particle beam enters the central bore; and an aperture within the annular detection unit, the aperture being characterized by a size ranging from about 0.3 mm to 2 mm in diameter.