Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
2001-08-06
2004-04-13
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C355S053000
Reexamination Certificate
active
06720680
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a planar motor unit and its driving method, a stage unit and its driving method, an exposure apparatus and exposure method, and a device and device manufacturing method, and more specifically to a planar motor unit that generates a driving force and its driving method, a stage unit that drives a stage by the use of the planar motor unit and its driving method, an exposure apparatus and exposure method that perform exposure while controlling position of a body mounted on the stage by the use of the stage unit, and a device manufactured by using the exposure apparatus and manufacturing method.
BACKGROUND ART
In a lithography process for manufacturing semiconductor devices, liquid crystal display devices, or the like, an exposure apparatus has been used that transfers a pattern formed on a mask or reticle (both referred to as a “reticle” hereinafter) onto a wafer or a substrate such as a glass plate (referred to as a “substrate” or “wafer” hereinafter, as needed), which is coated with a resist, through a projection optical system. As such an exposure apparatus, a stationary-exposure-type projection exposure apparatus, e.g. a so-called stepper, and a scanning-exposure-type projection exposure apparatus, e.g. a so-called scanning-stepper, are mainly used. These projection exposure apparatuses comprise a stage unit, which is movable in two dimensions while holding a wafer, so as to transfer a pattern formed on a reticle onto a plurality of shot areas on the wafer sequentially.
Such a stage unit needs to have the capability of highly accurately positioning a wafer for accurate exposure and also the capability of positioning a wafer at high speed for high throughput of exposure. In these needs, stage units have been developed which accurately position a wafer at higher speed without being affected by mechanical precision of the guide surface, etc., while driving the table, on which the wafer is mounted, in non-contact and in two dimensions so as to avoid mechanical friction and to prolong the life. With respect to the driving source of such a stage unit, a stage unit using a planar-motor having two linear pulse motors, of a variable-magnetic-reluctance driving method, each for an axis, and a stage unit using a planar motor as a driving unit employing an electromagnetic-force driving method disclosed in, for example, Japanese-Patent Laid-Open No. 58-175020 and U.S. Pat. No. 5,196,745 have been suggested.
The electromagnetic-force driving method has the advantages that theoretical design on the basis of the Lorentz force can be easily performed, and that the linearity between a current and a thrust is good up to a high frequency, and is also excellent in controllability because the variation of the thrust is small if using no iron core. Meanwhile, it has been difficult to obtain a driving force equivalent to that of the variable-magnetic-reluctance driving method. However, due to recent remarkable development of high-performance permanent magnets, a permanent magnet of which the energy product is more than 3×10
5
[T.A/m] (about 4×10
7
[G.Oe]) is available in the market, and the electromagnetic-force driving method is attracting attention.
Such a planar motor of the electromagnetic-force driving method, which can generate a force of large magnitude, comprises a magnetic pole unit having magnets and an armature unit having armature coils, and generates a driving force of electromagnetic interaction by supplying currents to the armature coils of the armature unit facing an alternating magnetic field which is generated by the magnetic pole unit and which is periodic in space. Upon supplying currents to the armature unit, the relative position and speed between the armature unit and the magnetic pole unit are controlled by supplying, for example, sine-wave currents each having a different phase, according to the positional relation between the armature unit and the magnetic pole unit. Therefore, the detection of the positional relation between the armature unit and the magnetic pole unit is indispensable, and at least three position-detection means are necessary to control translational movement on a movement plane (movement in a X-direction and Y-direction) and rotation (&thgr;) or yaw about an axis (Z axis) perpendicular to the movement plane.
As such a position-detection means, exposure apparatuses employ, for example, a laser interferometer system including a plurality of laser interferometers, which system can achieve high resolution in non-contact. Such a laser interferometer is provided on a fixed side and obtains position of a stage as a movable side by making a laser beam incident on a movable mirror provided on the stage and detecting the reflected beam. Therefore, the X-Y position and yaw &thgr; of the stage can be detected with high resolution. However, because in the laser interferometer the position of sending out the laser beam and the position of receiving the reflected beam are fixed, the yaw angle of the stage that can be detected is restricted by the detection limits of the reflected light. Therefore, when the yaw of the stage greatly changes because of malfunction or external disturbance, the position and yaw of the stage cannot be detected; the position control of the stage (including the yaw control) has to be suspended, and manual intervention is necessary to resume the position control of the stage.
The present invention has been made in such circumstances. A first object of the present invention is to provide a planar motor unit that can detect the position and yaw of a mover with respect to a stator regardless of the positional relation between the mover and the stator.
Furthermore, a second object of the present invention is to provide a stage unit that can detect its position and yaw regardless of variation amount of the yaw of the stage, and driving method thereof.
Moreover, a third object of the present invention is to provide an exposure apparatus and method that can detect the position and yaw of the stage unit regardless of variation amount of the yaw of the stage and control position of the stage for exposure operation.
Additionally, a fourth object of the present invention is to provide a device having a fine pattern accurately formed thereon, and manufacturing method thereof.
DISCLOSURE OF INVENTION
According to a first aspect of this invention, there is provided a first planar motor comprising: a stator having a coil; and a mover having a magnetic flux generator, the planar motor moving the mover on a movement plane, further comprising: a controller that detects position information of the mover based on information concerning an inductance of the coil, the inductance varying in accordance with the relative-position relation between the stator and the mover. The “magnetic flux generator” may be a magnet, a magnet module or the like that actively generates a magnetic field and that is equivalent to the above magnetic unit.
According to this, the controller detects position information of the mover based on information concerning an inductance of the coil, the inductance varying in accordance with the relative-position relation between the stator and the mover. Therefore, even if the position and yaw of the mover relative to the stator greatly change due to malfunction or external disturbances, the position information of the mover relative to the stator can be successively detected.
There is provided a planar motor according to the first planar motor, wherein the stator comprises a plurality of coils, and wherein the controller detects position information of the mover based on an inductance distribution with respect to the plurality of coils, the inductance distribution being generated in accordance with the relative-position relation between the stator and the mover.
In addition, in the first planar motor, the stator may comprise a coil-supporting member that is made of a magnetic material and that supports the plurality of coils. In this case, because a magnetic circuit
Jones Judson H.
Mullins Burton S.
Nikon Corporation
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