Patent ID: 6894291
Filing Date: 2005-05-17
Classification: B82Y,H01J

Abstract:
1. In a charged-particle-beam (CPB) microlithography apparatus, a CPB optical system, comprising: an illumination-optical system situated and configured to direct a charged-particle illumination beam onto a selected region of a reticle defining a pattern to be transferred to a sensitive substrate, the reticle being configured with relatively low-scattering regions and relatively high-scattering regions that collectively define the pattern, the low-scattering regions being transmissive to the illumination beam while causing little to no scattering of charged particles of the beam, and the high-scattering regions being transmissive to the illumination beam while causing comparatively large scattering, relative to the low-scattering regions, of charged particles of the beam; and a projection-optical system situated downstream of the illumination-optical system and configured to direct a patterned beam, formed by passage of the illumination beam through the selected region on the reticle and carrying an aerial image of a respective portion of the pattern defined in the selected region, to a corresponding location on a sensitive substrate, the projection-optical system comprising a first projection lens situated axially closer to the reticle and having a back focal plane, a second projection lens situated axially closer to the substrate, and a cutoff-plate assembly situated between the reticle and the back focal plane, the cutoff-plate assembly defining an aperture configured to block downstream propagation of at least 90% of the patterned beam scattered from the high-scattering regions of the reticle.