Linear motor magnetic shield apparatus for lithographic systems

摘要

A magnetic shield having non-magnetic gaps provides reduced magnetic cross-talk for a linear motor array in a precision positioning system. Redirecting the leakage flux limits the cross-talk and associated deleterious effects. Such preferred magnetic circuit paths for the leakage are affixed to the moving magnet system of the linear motor. Embodiments of the preferred flux leakage paths are realized by providing a ferromagnetic shield separated by a non-magnetic gap between the permanent magnets and the back-irons. In another embodiment, the ferromagnetic shield separation includes diamagnetic materials.

主权项

1. A device manufacturing method, comprising:
projecting a patterned beam of radiation toward a substrate stage; positioning the substrate stage using a linear motor, the linear motor comprising:
a first back iron and a second back iron extending in a first direction;a first plurality of magnetized poles arranged with alternating polarity to each other in the first direction, wherein the first plurality of magnetized poles are coupled to the first back iron;a second plurality of magnetized poles arranged with alternating polarity to each other in the first direction, wherein the second plurality of magnetized poles are coupled to the second back iron and wherein the second plurality of magnetized poles are arranged opposite to the first plurality of magnetized poles;a coil disposed within a gap between the first plurality of magnetized poles and the second plurality of magnetized poles;a first shield comprising a first part and a second part detached from the first part, wherein the first shield is disposed in a first leakage flux pathway and is separated from the first plurality of magnetized poles and the first back iron; anda second shield comprising a third part and a fourth part detached from the third part, wherein the second shield is disposed in a second leakage flux pathway and is separated from the second plurality of magnetized poles and the second back iron,wherein the first back iron is located between the first part and the second part, the second back iron is located between the third part and the fourth part, and the third and the fourth parts of the second shield are detached from the first and second parts of the first shield.