Patent ID: 6011268
Filing Date: 2000-01-04
Classification: H01J

Abstract:
A projection-optical system for projecting an image of a mask pattern region, irradiated by an electron beam, onto a substrate, the projection-optical system comprising from mask-wise to substrate-wise on an optical axis:(a) a first projection lens comprising a pole piece, a main coil for conducting electrical current to cause the pole piece to generate a magnetic field extending along the optical axis, a magnetic shield, and an auxiliary lens, the main coil being concentric with the pole piece, the magnetic shield being axially coextensive with the main coil and being situated radially interiorly to an inside diameter of the main coil, and the auxiliary lens comprising at least one coil and being axially coextensive with the main coil, the auxiliary lens being situated radially interiorly to the magnetic shield;(b) a second projection lens comprising a pole piece, a main coil for conducting electrical current to cause the pole piece to generate a magnetic field extending along the optical axis, a magnetic shield, and an auxiliary lens, the main coil being concentric with the pole piece, the magnetic shield being axially coextensive with the main coil and being situated radially interiorly to an inside diameter of the main coil, and the auxiliary lens comprising at least one coil and being axially coextensive with the main coil, the auxiliary lens being situated radially interiorly to an inside diameter of the magnetic shield; and(c) the second projection lens being dimensioned relative to the first projection lens according to a demagnification ratio of the projection-optical system.