Abstract: A method and apparatus for controlling the leveling table of a wafer stage is described. More generally, the invention includes control circuitry for controlling motion of a stage, where the stage is adapted to support a workpiece. The control circuitry measures position in a vicinity of the workpiece. Based upon the measured position, the control circuitry drives the stage toward a target position while accounting for nonlinear dynamics of the stage. The nonlinear dynamics may include inertia, in which case the control circuitry adaptively estimates the inertia of the stage. The nonlinear dynamics may also include tilt due to acceleration or deceleration of the stage, in which case the circuitry adaptively estimates the tilt of the stage. The stage may generally travel in a plane, and the circuitry measures position in a direction orthogonal to the plane. The circuitry may measure the position of the workpiece itself, or the position of an upper surface of the stage.

Abstract: A positioning method in which a system performs operations relative to areas on a substrate by a series of relative movements between the system and substrate scanning exposures. The method includes the steps of disposing a first area relative to a system performing an operation relative to the first area, and moving the substrate from a first position where the first operation relative to the first area has finished to a second position where a second operation relative to a second area is to start, and synchronously moving the system from a third position where the first operation relative to the first area has finished to a fourth position where the second operation relative to the second area is to start. An acceleration of the substrate during movement from the first position to the second position and an acceleration of the system during movement from the third position to the fourth position continually have absolute values greater than zero.

Abstract: A pair of complementary magnetic actuators controls a stage in a high-precision positioning instrument in a single coordinate direction. Additional pairs of complementary magnetic actuators can be used to provide control of the stage in other coordinate directions. A small current through the windings of both magnetic actuators provides a zero net force on the fine stage, thus maintaining the position of the fine stage. The small current used to control the fine stage minimizes the RMS power gain. By increasing the current in one magnetic actuator while decreasing the current in the other, a net force is generated for large accelerations of the stage. Control of the magnetic actuators is simplified by simultaneously increasing and decreasing the current through the windings of the complementary magnetic actuators prior to accelerating the stage. Additionally, a feedforward command can control the magnetic actuators to decrease the settling time of the system.

Abstract: A fine stage control system for use for instance in a semiconductor lithography machine, uses a pair of opposing (push-pull) E/I core actuators to move the stage with high precision along an axis. The paired actuators are coupled together mathematically in terms of their control characteristics and controlled as a single entity, thereby providing a more efficient control scheme and improved system performance.

Abstract: A position control apparatus for synchronously controlling the movement of fine stages in a high-precision scanning positioning instrument. The position control apparatus uses actuators to adjust the fine stages with six degrees of freedom. By adjusting the fine stages, any synchronous errors between the fine stages during scanning may be dynamically corrected. Further, the fine stages may be adjusted during periods of acceleration and deceleration to reduce the settling time and consequently increasing throughput. Encoders directly attached to the actuators produce signals that are used in a velocity feedback loop. The locations of the fine stages are measured by interferometers. The position control apparatus uses a position control circuit to control the actuators to compensate for synchronous error.

Abstract: An improvement in the performance characteristics of a controller for a high precision positioning system, by continuously updating a variable parameter in the controller transfer function in response to, and as a continuously monotonically decreasing function of, the measured position error signal, with a small error cutoff. The error convergence, noise, and stability characteristics of the controller are improved over that of a constant-parameter controller. The variable parameter can also be tailored to prevent saturation of the amplifier that is driven by the controller and which drives the mechanical system whose position is being controlled.

Abstract: A voice coil motor has a flux return housing with at least one magnet and a soft iron cantilevered core. A coil holder, including an electrical coil spaced from magnet, is telescoped over the core with an air gap between the sides of the coil holder and the sides of core. The coil holder has an open end and a closed end forming with the distal end of the core a pressurized air bellows, which can vertically support a payload such as a Z-axis motion stage. The coil holder is telescopically movable with respect to the core along the air gap supplied with pressurized air through longitudinal air ducts in the core and through transverse orifices extending from the ducts to the air gap. A regulator is connected to a core central bore for adjusting pressure in a bellows chamber between the coil holder closed end and the distal end of the core for supporting the payload.