Flat motor device and its driving method, stage device and its driving method, exposure apparatus and exposure method, and device and its

Claims

What is claimed is:

1. A 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 by electromagnetic force which is generated between the coil and the magnetic flux generator, 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.

2. A planar motor according to claim 1,

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.

3. A planar motor according to claim 2,

wherein the stator comprises a coil-supporting member that is made of a magnetic material and that supports the plurality of coils.

4. A planar motor according to claim 1,

wherein the position information of the mover includes at least one of a piece of position information with respect to a first axis direction and a second axis direction that define the movement plane, and a piece of position information with respect to rotation about a third axis perpendicular to the first axis direction and the second axis direction.

5. A planar motor according to claim 1,

wherein the controller controls an electric current supplied to the coil based on a detection result of position information of the mover.

6. A planar motor according to claim 1,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction almost perpendicular to the movement plane.

7. A planar motor according to claim 6,

wherein the magnetic flux generator further comprises a magnet-supporting member that is made of a magnetic material and that supports the plurality of magnets.

8. A planar motor according to claim 1,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction not perpendicular to the movement plane.

9. A planar motor according to claim 1, further comprising:

an inductance measurement unit to measure an inductance of the coil.

10. A planar motor comprising: a stator having a coil; and a mover having a magnet, the planar motor moving the mover on a movement plane by eletromagnetic force which is generated between the coil and the magnet, further comprising:

a controller that controls position 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.

11. A planar motor according to claim 10,

wherein the stator comprises a plurality of coils, and

wherein the controller controls position 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.

12. A planar motor according to claim 10, further comprising:

an inductance measurement unit to measure an inductance of the coil.

13. A stage unit comprising:

a planar motor according to claim 1; and

a stage member connected with the mover.

14. An exposure apparatus comprising:

an illumination system sending out illumination light for exposure; and

a stage unit according to claim 13 on which an object to be arranged in a path of the illumination light is mounted.

15. A device on which a predetermined pattern is formed, and which is manufactured by using an exposure apparatus according to claim 14.

16. A stage unit comprising:

a stage member moving on a movement plane;

a driving unit comprising: a mover that has a magnetic flux generator and that is provided on the stage member and a stator having a plurality of coils, the driving unit driving the stage member by electromagnetic force which is generated between the coils and the magnetic flux generator;

an inductance measurement unit to measure inductances of the coils; and

a controller to control respective electric currents supplied to the plurality of coils based on measurement results by the inductance measurement unit.

17. A stage unit according to claim 16,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction almost perpendicular to the movement plane.

18. A stage unit according to claim 17,

wherein the stage member is made of a non-magnetic material, and

wherein the magnetic flux generator further comprises a magnet-supporting member that is made of a magnetic material and that supports the plurality of magnets.

19. A stage unit according to claim 16,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction not perpendicular to the movement plane.

20. A stage unit according to claim 16,

wherein the stator comprises a coil-supporting member that is made of a magnetic material and that supports the plurality of coils.

21. A stage unit according to claim 20, further comprising:

a position detection unit to detect position of the stage member, and

wherein the controller controls respective electric currents supplied to the plurality of coils based on at least one of a detection result by the position detection unit and a set of measurement results by the inductance measurement unit.

22. A stage unit according to claim 21,

wherein when the position detection unit can detect position of the stage member, the controller controls position of the stage member by controlling respective electric currents supplied to the plurality of coils based on a detection result by the position detection unit, and

wherein when the position detection unit cannot detect position of the stage member, the controller controls position of the stage member by controlling respective electric currents supplied to the plurality of coils based on measurement results by the inductance measurement unit.

23. An exposure apparatus comprising:

an illumination system sending out illumination light for exposure; and

a stage unit according to claim 16, on which an object to be arranged in a path of the illumination light is mounted.

24. An exposure apparatus according to claim 23,

wherein the object is a substrate which is exposed by the illumination light, and onto which a predetermined pattern is transferred.

25. An exposure apparatus comprising:

an illumination system sending out illumination light for exposure; and

a stage unit according to claim 21, on which an object to be arranged in a path of the illumination light is mounted.

26. An exposure apparatus according to claim 25,

wherein the object is a substrate which is exposed by the illumination light, and onto which a predetermined pattern is transferred.

27. An exposure apparatus according to claim 25,

wherein when the position detection unit can detect position of the stage member, the controller controls position of the stage member by controlling respective electric currents supplied to the plurality of coils based on a detection result by the position detection unit, wherein when the position detection unit cannot detect position of the stage member, the controller controls position of the stage member by controlling respective electric currents supplied to the plurality of coils based on measurement results by the inductance measurement unit, and

wherein upon exposure, when it is judged that the reason why the position detection unit cannot detect position of the stage member is the stage member being out of a range over which the position detection unit can detect position thereof, the controller restores the stage member to within the detection range of the position detection unit based on measurement results by the inductance measurement unit.

28. An exposure apparatus according to claim 27,

wherein after restoration of the stage member, the controller continues to control position of the stage member for exposure based on a detection result by the position detection unit.

29. An exposure apparatus according to claim 27,

wherein after restoration of the stage member, the controller moves the stage member to an initial position based on a detection result by the position detection unit.

30. An exposure apparatus according to claim 27,

wherein when the position detection unit can detect position of the stage member, the controller controls position of the stage member by controlling respective electric currents supplied to the plurality of coils based on a detection result by the position detection unit, wherein when the position detection unit cannot detect position of the stage member, the controller controls position of the stage member by controlling respective electric currents supplied to the plurality of coils based on measurement results by the inductance measurement unit, and

wherein upon exposure, when the position detection unit cannot detect position of the stage member, the controller controls position of the stage member for exposure based on measurement results by the inductance measurement unit.

31. A device on which a predetermined pattern is formed, and which is manufactured by using an exposure apparatus according to claim 23.

32. A device on which a predetermined pattern is formed, and which is manufactured by using an exposure apparatus according to claim 25.

33. A driving method that drives a planar motor comprising: a stator having a coil; and a mover having a magnetic flux generator, so as to move the mover on a movement plane by electromagnetic force which is generated between the coil and the magnetic flux generator,

wherein position information of the mover is detected 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.

34. A driving method of a planar motor according to claim 33,

wherein the stator comprises a plurality of coils, and

wherein position information of the mover is detected 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.

35. A driving method of a planar motor according to claim 34,

wherein the stator comprises a coil-supporting member that is made of a magnetic material and that supports the plurality of coils.

36. A driving method of a planar motor according to claim 34,

wherein inductances of the plurality of coils are measured individually.

37. A driving method of a planar motor according to claim 33,

wherein the position information of the mover includes at least one of a piece of position information with respect to a first axis direction and a second axis direction that define the movement plane, and a piece of position information with respect to rotation about a third axis perpendicular to the first axis direction and the second axis direction.

38. A driving method of a planar motor according to claim 33,

wherein an electric current supplied to the coil is controlled based on a detection result of position information of the mover.

39. A driving method of a planar motor according to claim 33,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction almost perpendicular to the movement plane.

40. A driving method of a planar motor according to claim 39,

wherein the magnetic flux generator further comprises a magnet-supporting member that is made of a magnetic material and that supports the plurality of magnets.

41. A driving method of a planar motor according to claim 33,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction not perpendicular to the movement plane.

42. A driving method that drives a stage unit comprising a planar motor which comprises a stator having a coil and a mover having a magnetic flux generator, and which moves the mover on a movement plane, and a stage member moving as one entity with the mover,

wherein upon moving the stage member is used a driving method of a planar motor according to claim 33.

43. An exposure method comprising the steps of sending out illumination light for exposure and, by driving a stage unit on which an object is mounted, moving the object relative to a path of the illumination light,

wherein upon driving the stage unit is used a driving method of a stage unit according to claim 42.

44. A device manufacturing method including a lithography process, wherein the lithography process uses an exposure method according to claim 43.

45. A driving method that drives a planar motor comprising: a stator having a coil; and a mover having a magnet, so as to move the mover on a movement plane by electromagnetic force which is generated between the coil and the magnet,

wherein position of the mover is controlled 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.

46. A driving method of a planar motor according to claim 45,

wherein the stator comprises a plurality of coils, and

wherein position of the mover is controlled 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.

47. A driving method of a planar motor according to claim 46,

wherein inductances of the plurality of coils are measured individually.

48. A driving method that drives a stage unit comprising a stage member moving on a movement plane and a driving unit comprising a mover which has a magnetic flux generator and which is provided on the stage member and a stator having a plurality of coils and driving the stage member by electromagnetic force which is generated between the coils and the magnetic flux generator,

wherein respective electric currents supplied to the plurality of coils are controlled based on results of measuring inductances of the plurality of coils.

49. A driving method of a stage unit according to claim 48,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction almost perpendicular to the movement plane.

50. A driving method of a stage unit according to claim 49,

wherein the stage member is made of a non-magnetic material, and

wherein the magnetic flux generator further comprises a magnet-supporting member that is made of a magnetic material and that supports the plurality of magnets.

51. A driving method of a stage unit according to claim 48,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction not perpendicular to the movement plane.

52. A driving method of a stage unit according to claim 48,

wherein the stator comprises a coil-supporting member that is made of a magnetic material and that supports the plurality of coils.

53. A driving method of a stage unit according to claim 52,

wherein the stage unit further comprises a position detection unit to detect position of the stage member, and

wherein respective electric currents supplied to the plurality of coils are controlled based on at least one of a detection result by the position detection unit and a set of measurement results of the inductances.

54. A driving method of a stage unit according to claim 53,

wherein when the position detection unit can detect position of the stage member, position of the stage member is controlled by controlling respective electric currents supplied to the plurality of coils based on the result of detecting position, and

wherein when the position detection unit cannot detect position of the stage member, position of the stage member is controlled by controlling respective electric currents supplied to the plurality of coils based on measurement results of the inductances.

55. An exposure method comprising the steps of sending out illumination light for exposure and, by driving a stage unit on which an object is mounted, moving the object relative to a path of the illumination light,

wherein upon driving the stage unit is used a driving method of a stage unit according to claim 48.

56. An exposure method according to claim 55, wherein the object is a substrate which is exposed by the illumination light, and onto which a predetermined pattern is transferred.

57. An exposure method comprising the steps of sending out illumination light for exposure and, by driving a stage unit on which an object is mounted, moving the object relative to a path of the illumination light,

wherein upon driving the stage unit is used a driving method of a stage unit according to claim 53.

58. An exposure method according to claim 57,

wherein the object is a substrate which is exposed by the illumination light, and onto which a predetermined pattern is transferred.

59. An exposure method according to claim 57,

wherein when the position detection unit can detect position of the stage member, position of the stage member is controlled by controlling respective electric currents supplied to the plurality of coils based on the result of detecting position, and wherein when the position detection unit cannot detect position of the stage member, position of the stage member is controlled by controlling respective electric currents supplied to the plurality of coils based on measurement results of the inductances, and

wherein upon exposure, when it is judged that the reason why the position detection unit cannot detect position of the stage member is the stage member being out of a range over which the position detection unit can detect position thereof, the stage member is restored to within the detection range of the position detection unit based on measurement results of the inductances.

60. An exposure method according to claim 59,

wherein after restoration of the stage member, position of the stage member continues to be controlled for exposure based on a detection result by the position detection unit.

61. An exposure method according to claim 59,

wherein after restoration of the stage member, the stage member is moved to an initial position based on a detection result by the position detection unit.

62. An exposure method according to claim 57,

wherein when the position detection unit can detect position of the stage member, position of the stage member is controlled by controlling respective electric currents supplied to the plurality of coils based on a result of detecting position of the stage member, wherein when the position detection unit cannot detect position of the stage member, position of the stage member is controlled by controlling respective electric currents supplied to the plurality of coils based on measurement results of the inductances, and

wherein upon exposure, when the position detection unit cannot detect position of the stage member, position of the stage member is controlled for exposure based on measurement results of the inductances.

63. A device manufacturing method including a lithography process, wherein the lithography process uses an exposure method according to claim 55.

64. A device manufacturing method including a lithography process, wherein the lithography process uses an exposure method according to claim 57.

65. A stage unit comprising:

a planar motor according to claim 10; and

a stage member connected with the mover.

66. A driving method that drives a stage unit comprising a planar motor which comprises a stator having a coil and a mover having a magnetic flux generator, and which moves the mover on a movement plane, and a stage member moving as one entity with the mover,

wherein upon moving the stage member is used a driving method of a planar motor according to claim 45.

67. A 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,

wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction not perpendicular to the movement plane,

and the planar motor 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.

68. A stage unit comprising:

a stage member moving on a movement plane;

a driving unit comprising: a mover that has a magnetic flux generator comprising a plurality of magnets magnetized in a direction not perpendicular to the movement plane and that is provided on the stage member, and a stator having a plurality of coils, the driving unit driving the stage member by electromagnetic force;

an inductance measurement unit to measure inductances of the coils; and

a controller to control respective electric currents supplied to the a plurality of coils based on measurement results by the inductance measurement unit.

69. A stage unit comprising:

a stage member moving on a movement plane;

a driving unit comprising: a mover that has a magnetic flux generator and that is provided on the stage member and a stator having a plurality of coils, the driving unit driving the stage member by electromagnetic force;

an inductance measurement unit to measure inductances of the coils;

a position detection unit to detect position of the stage member; and

a controller to control respective electric currents supplied to the plurality of coils based on at least one of a detection result by the position detection unit and a set of measurement results by the inductance measurement unit.

70. An exposure apparatus comprising:

an illumination system sending out illumination light for exposure; and

a stage unit according to claim 69, on which an object to be arranged in a path of the illumination light is mounted.

71. A driving method that drives a planar motor comprising: a stator having a coil; and a mover having a magnetic flux generator, so as to move the mover on a movement plane, wherein the magnetic flux generator comprises a plurality of magnets magnetized in a direction not perpendicular to the movement plane, and

wherein position information of the mover is detected 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.

72. A driving method that drives a stage unit comprising a stage member moving on a movement plane and a driving unit comprising a mover which has a magnetic flux generator comprising a plurality of magnets magnetized in a direction not perpendicular to the movement plane and which is provided on the stage member, and a stator having a plurality of coils and driving the stage member by electromagnetic force,

wherein respective electric currents supplied to the plurality of coils are controlled based on results of measuring inductances of the plurality of coils.

73. A driving method that drives a stage unit comprising: a stage member moving on a movement plane and a driving unit comprising a mover which has a magnetic flux generator and which is provided on the stage member and a stator having a plurality of coils and driving the stage member by electromagnetic force,

wherein the stage unit further comprises a position detection unit to detect position of the stage member, and

wherein respective electric currents supplied to the plurality of coils are controlled based on at least one of a detection result by the position detection unit and a set of measurement results of the inductances.

74. An exposure method comprising the steps of sending out illumination light for exposure and, by driving a stage unit on which an object is mounted, moving the object relative to a path of the illumination light,

wherein upon driving the stage unit is used a driving method of a stage unit according to claim 73.

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.times.10.sup.5 [T.A/m] (about 4.times.10.sup.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 (.theta.) 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 .theta. 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 is formed through the coil-supporting member made of a magnetic material, the magnetic circuit has low magnetic reluctance and is stable, and the inductances of the coils can greatly vary according to the relative-position relation between the stator and the mover. Accordingly, position information of the mover can be easily detected based on the inductance distribution.

Furthermore, there is provided a planar motor according the first planar motor, wherein the position information of the mover includes at least one of a piece of position information with respect to a first axis direction and a second axis direction that define the movement plane, and a piece of position information with respect to rotation about,a third axis perpendicular to the first axis direction and the second axis direction. That is, position information of the mover to be detected may be position information with respect to at least one of three degrees of freedom in a plane parallel to the movement plane.

Moreover, in the first planar motor of this invention, the controller may control an electric current supplied to the coil based on a detection result of position information of the mover. In this case, by the controller controlling an electric current supplied to the coil based on a detection result of position information of the mover, a Lorentz force generated in the coil can be controlled, and thus the reaction against the Lorentz force, which reaction is a driving force to the mover, can be controlled. Therefore, by controlling the driving force to the mover according to the position of the mover, the position of the mover can be accurately controlled.

In addition, in the first planar motor of this invention, the magnetic flux generator may comprise a plurality of magnets magnetized in a direction almost perpendicular to the movement plane. Also, the magnetic flux generator may further comprise a magnet-supporting member that is made of a magnetic material and that supports the plurality of magnets. In this case, because a magnetic circuit is formed through the magnet-supporting member made of a magnetic material, the magnetic circuit has low magnetic reluctance and is stable, and the inductances of the coils can greatly vary according to the positional relation between the magnet-supporting member and the coils. Accordingly, position information of the mover can be easily detected based on the inductance distribution.

Moreover, in the first planar motor of this invention, the magnetic flux generator may comprise a plurality of magnets magnetized in a direction not perpendicular to the movement plane. In this case, because no magnetic member is needed to constitute the stable magnetic circuit, the mover becomes lightweight.

It is noted that the magnetic flux generator may comprise a plurality of magnets magnetized in a direction almost perpendicular to the movement plane, and a plurality of magnets magnetized in a direction not perpendicular to the movement plane, needless to say.

Furthermore, the first planar motor of this invention may further comprise an inductance measurement unit to measure an inductance of the coil. In this case, by the inductance measurement unit measuring an inductance of the