Optical system for charged-particle-beam microlithography apparatus exhibiting reduced third- and fifth-order aberrations

摘要

Charged-particle-beam (CPB) optical systems are disclosed, especially for use in CPB microlithography apparatus. A typical such system preferably includes first and second projection lenses (preferably in a Symmetric Magnetic Doublet configuration) and an aberration-correcting deflector system preferably comprising first and second deflector groups. Each deflector group preferably comprises multiple (e.g., three) deflectors displaced in an axial direction in association with the respective projection lenses. One or more deflectors in each group can comprise multiple micro-deflectors linearly arranged in an optical axis direction. The micro-deflectors can extend fully between the object surface and aperture surface of the projection lens and/or between the aperture surface and image surface of the projection lens. The deflectors in each group collectively form a deflection field that corrects off-axis third-order aberrations and on-axis third-order aberrations of the projection lenses substantially equally. The deflectors can also be configured to also minimize fifth-order blur generated by the deflection.