BACKGROUND

Stage assemblies are commonly used to position and move a device during manufacturing, testing, or inspection operation. A typical stage assembly includes a stage base, a stage that retains the device and a stage mover assembly (“mover”) that precisely positions the stage and the device. In many applications, such as semiconductor wafer processing, the precise positioning of the wafer is critical to the manufacturing of high density, semiconductor wafers.

Recently, planar motors have been used in the stage mover assembly. Unfortunately, the planar motors are difficult to control and position accurately.

SUMMARY

A method for moving a stage relative to a base from a measured position to a desired position includes coupling a magnet assembly to the stage; coupling an array of coils to the base; and directing current to at least one of the coils with a control system that includes a processor to generate a force that levitates the stage relative to the base and moves the stage relative to the base. In one embodiment, the control system generates at least one current command that levitates and moves the stage while inhibiting the excitation of a first targeted flexible mode.

As alternative, non-exclusive examples, the targeted flexible mode can be flexible mode one, flexible mode two, flexible mode three, flexible mode four, flexible mode five, or flexible mode six.

Additionally, the method can include the step identifying first force constants for the first targeted flexible mode. In this embodiment, the step of directing current includes the step of utilizing the first force constants in the active damping control of the first targeted flexible mode.

Moreover, the step of directing current can include the control system generating at least one current command that levitates and moves the stage while inhibiting the excitation of a second targeted flexible mode. In this embodiment, the method can include identifying second force constants for the second targeted flexible mode; and the step of directing current includes the step of utilizing the second force constants in the active damping control of the second targeted flexible mode.

Further, the step of directing current can include the control system generating at least one current command that levitates and moves the stage while inhibiting the excitation of a third targeted flexible mode. In this embodiment, the method can include identifying third force constants for the third targeted flexible mode; and the step of directing current includes the step of utilizing the third force constants in the active damping control of the third targeted flexible mode.

Moreover, the step of directing current can include the control system including a flexible mode feedback controller that uses phase correction to reduce the influence of phase lag on the flexible mode control.

In one embodiment, the control system utilizes a pseudo inverse based commutation to generate at least one current command that accounts for a rigid body mode of the stage and at least one flexible mode of the stage.

In certain embodiments, one or more flexible mode sensors are coupled to the stage that generates flexible mode information. For example, the first force constants for the first targeted flexible mode can be identified using the flexible mode information.

The present invention is directed to a stage mover assembly, an exposure apparatus, a method for making a semiconductor wafer, and a method for moving and positioning a device.

