Patent ID: 6924494

Claim:
A charged particle beam lithography system for exposing a target comprising: a source of a charged particle beam; a first lens located coaxial to and downstream with regard to a direction of propagation of the beam from the source for directing the beam to the target; a variable axis immersion lens located coaxial to the beam and downstream from the first lens, the variable axis immersion lens comprising: at least two optical axis deflection coils located coaxial to the charged particle beam which optical axis deflection coils are used to shift the optical axis of the charged particle beam to be coincident with a downstream deflected electron beam; an excitation coil that generates a magnetic field, which is a focusing magnetic field; and a magnetically floating field shield located coaxial to the beam and downstream from the deflection coils; and a support for the target downstream from the immersion lens, wherein the magnetically floating field shield is located intermediate the deflection coils and the support, thereby limiting a magnetic field generated by the deflection coils from radiating downstream from the magnetically floating field shield into areas protected by the magnetically floating field shield.