Linear motors and stages comprising same that produce reduced magnetic fields at an optical axis for charged-particle-beam lithography

A stage assembly for a CPB lithographic exposure system, comprising:

• a stage extending in an X-Y plane perpendicular to an optical axis, the stage being configured for holding a reticle or substrate and for moving the reticle or substrate in a movement direction in the X-Y plane;
• and
• a moving-coil type linear motor operatively coupled to the stage, the linear motor comprising first and second linear-motor portions that are disposed in respective positions that are symmetric with respect to a plane including the optical axis and extending perpendicularly to the X-Y plane and parallel to the movement direction of the stage, each linear-motor portion comprising a respective permanent magnet split into multiple respective magnet subunits, wherein the magnet subunits of the first linear-motor portion are disposed relative to the magnet subunits of the second linear-motor portion in a point-symmetrical manner with respect to a point at which the X-Y plane intersects the optical axis.

A stage assembly for a CPB lithographic exposure system, comprising:

• a stage configured for holding a reticle or substrate, the stage extending in an X-Y plane perpendicular to an optical axis that is parallel to a Z axis;
• and
• a moving-magnet type of linear motor operatively coupled to the stage for moving and positioning the stage in a movement direction in the X-Y plane, the linear motor comprising multiple permanent-magnet subunits and multiple corresponding dummy permanent-magnet subunits, wherein the magnet subunits and the dummy-magnet subunits are arranged so as to move symmetrically with respect to a plane that is perpendicular to the movement direction and that includes the optical axis.

In a method for performing lithographic exposure of a pattern onto a substrate using a charged particle beam passing through a charged-particle-beam (CPB) optical system of a CPB lithographic exposure apparatus that includes a stage extending in an X-Y plane and driven in an X-axis or Y-axis direction by a linear motor, a method for reducing the magnitude of a magnetic field produced by the linear motor at an optical axis of the CPB optical system, the optical axis being perpendicular to the X-Y plane, the method comprising:

• configuring the linear motor with multiple permanent-magnet subunits arranged symmetrically with respect to a plane that is perpendicular to the X-Y plane, wherein at least two magnetic fields produced by respective subunits cancel at least a portion of each other at the optical axis;
• and
• driving the stage in the X-axis or Y-axis direction using the linear motor.

In a method for performing lithographic exposure of a pattern onto a substrate using a charged particle beam passing through a charged-particle-beam (CPB) optical system of a CPB lithographic exposure apparatus that includes a stage extending in an X-Y plane and driven in an X-axis or Y-axis movement direction by a moving-coil linear motor, a method for reducing the magnitude of a magnetic field produced by the linear motor at an optical axis of the CPB optical system, the optical axis being perpendicular to the X-Y plane, the method comprising:

• configuring the linear motor with first and second linear-motor portions and disposing the first and second linear-motor portions in respective positions that are symmetric with respect to a plane including the optical axis and extending perpendicularly to the X-Y plane and parallel to the movement direction;
• and
• configuring each linear-motor portion with a respective permanent magnet split into multiple respective magnet subunits, and disposing the magnet subunits of the first linear-motor portion relative to the magnet subunits of the second linear-motor portion in a point-symmetrical manner with respect to a point at which the X-Y plane intersects the optical axis.

In a method for performing lithographic exposure of a pattern onto a substrate using a charged particle beam passing through a charged-particle-beam (CPB) optical system of a CPB lithographic exposure apparatus that includes a stage extending in an X-Y plane and driven in an X-axis or Y-axis movement direction by a moving-magnet linear motor, a method for reducing the magnitude of a magnetic field produced by the linear motor at an optical axis of the CPB optical system, the optical axis being perpendicular to the X-Y plane, the method comprising:

• configuring the linear motor with multiple permanent-magnet subunits and multiple corresponding dummy permanent-magnet subunits;
• and
• arranging the magnet subunits and the dummy-magnet subunits so as to move symmetrically with respect to a plane that is perpendicular to the movement direction and that includes the optical axis.