Patent ID: 6906788
Filing Date: 2005-06-14
Classification: G03F

Abstract:
1. A lithographic projection apparatus comprising: a radiation system to transmit a beam of radiation emitted from a radiation source; a support structure constructed to hold a patterning structure to be irradiated by the beam of radiation, said patterning structure adapted to pattern the beam; a substrate holder constructed to hold a substrate; a projection system constructed and arranged to project an irradiated portion of the patterning structure onto a target portion of the substrate; a first screen positioned in a path of the beam of radiation between the radiation source and an optical element to be screened from positively charged particles, the first screen being substantially transparent to the beam of radiation, and a positive voltage being applied to the first screen to repel at least a portion of the positively charged particles away from the optical element; and a second screen positioned in the path of the beam of radiation on at least one side of the first screen, a negative voltage being applied to the second screen to repel negative particles away from the first screen.