Patent Number: 
Section: abstract

Charged-particle-beam (CPB)-optical systems, and CPB microlithography systems including such CPB-optical systems, are disclosed that exhibit improved shielding against external stray magnetic fields. For example, the systems and apparatus exhibit improved shielding against stray magnetic fields from peripheral conductors or moving conductors, such as linear motors used to drive the reticle stage and/or substrate stage. To such end, a magnetic shield can be attached to the downstream-facing edge of a vacuum wall covering the downstream-facing surface of the wafer-side projection lens. Similarly, a magnetic shield can be attached to the upstream-facing edge of a vacuum wall covering the upstream-facing surface of the reticle-side projection lens. The axis-facing surface of the magnetic shield can have a conical profile, and the magnetic shield can be situated just outside a zone for passage of a light beam for a Z-position sensor.