Patent ID: 6603131
Filing Date: 2003-08-05
Classification: B82Y,G21K,H01J

Abstract:
A charged-particle-beam (CPB) optical system, comprising:a shaping aperture situated and configured to receive a beam of charged particles propagating along an optical axis from a CPB source, the shaping aperture comprising a conductive thin-film membrane defining an aperture opening that transmits at least a portion of the beam incident on the shaping aperture and forms a shaped beam propagating downstream of the shaping aperture, the thin-film membrane scattering the charged particles of the beam incident on the membrane without absorbing the incident charged particles, such that the shaped beam and scattered charged particles propagate downstream of the shaping aperture; and a screening aperture situated downstream of the shaping aperture at a location at which the shaped beam forms a crossover, the screening aperture comprising a conductive sheet defining an aperture opening having a width dimension corresponding to a width dimension of the crossover so as to allow the shaped beam to pass through the aperture opening, the conductive sheet being sufficiently thick in an optical-axis direction so as to absorb charged particles, including charged particles scattered during transmission through the conductive thin-film membrane of the shaping aperture, incident on the sheet.