Patent ID: 6717143
Filing Date: 2004-04-06
Classification: H01J

Abstract:
A method for imaging a surface of a sample with an apparatus which directs a beam of charged particles at the surface and includes an objective lens and an electrostatic lens for controlling the particle beam to minimize at least one adverse effect induced by changes in operating parameters of the apparatus, the objective and electrostatic lenses forming a compound lens having an axis, comprising:deflecting the beam with at least one deflector toward a second deflector; deflecting the beam with the second deflector toward the sample surface; determining an optimum location in a plane within the second deflector from which the beam can be deflected by the second deflector to substantially travel along the axis of the compound lens; setting the at least one deflector to align the beam with said optimum location; and setting the second deflector to align the beam with the axis of the compound lens.