Patent ID: 6635891
Filing Date: 2003-10-21
Classification: H01J

Abstract:
A hollow-beam aperture for a charged-particle-beam (CPB) microlithography apparatus, comprising:a first member, multiple second members, and a circular center member made of a CPB-absorbing material, the circular member having a radius; the center member being supported relative to the first member by support bars extending radially from the first member to the center member; the second members being situated between the support bars and the first member, and the second members being displaceable relative to the first member radially toward the center member; the second members each having a distal edge, the distal edges being configured to engage the support bars whenever the second members are displaced maximally toward the center member; and the distal edges each defining a cutout having a respective edge configured as an arc having a radius greater than the radius of the center member such that, whenever the second members are displaced maximally toward the center member, a substantially annular aperture is defined between the center member and the cutouts.