JP2006246570A - Linear motor and exposure device using linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motor that is reduced in the weight of a movable body, and can reduce the heat generation of a coil. <P>SOLUTION: The linear motor comprises: the movable body arranged with a main-pole permanent magnet, and an auxiliary-pole permanent magnet that collects magnetic fields around the main-pole permanent magnet; and a stator coil that opposes the main-pole permanent magnet. The linear motor generates thrust based on a control current between the main-pole permanent magnet and the stator coil, and also comprises the main-pole permanent magnet that is arranged on a plane opposing the stator coil, and has a first permanent-magnet thickness, and the auxiliary permanent magnet that opposes the stator coil, is arranged on the same plane where the main-pole permanent magnet is arranged, and has a second permanent-magnet thickness. The first and the second permanent-magnet thicknesses satisfy a relation of the first permanent-magnet thickness>the second permanent magnet thickness. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a linear motor and an exposure apparatus using the linear motor.

  For an exposure apparatus that irradiates a glass substrate (hereinafter referred to as a “reticle”) on which a circuit pattern is drawn with exposure light and transfers the circuit pattern onto the wafer through a reduction optical system, a step-and-repeat method is used. Various types of apparatuses such as a reduction projection exposure apparatus (so-called “stepper”) and a step-and-scan scanning projection exposure apparatus (so-called “scanning stepper”) have been studied. Along with the high integration of semiconductors, high integration is also required for the circuit pattern transfer technology in the exposure apparatus. For example, the wafer or reticle to which the circuit pattern is transferred is placed at a predetermined position in a three-dimensional manner with high accuracy. There is a demand for a linear motor that can be positioned in a straight line.

  In addition, from the viewpoint of productivity of the exposure apparatus, a drive mechanism with high exposure processing capability (throughput) is required, and in particular, a linear motor that can be driven at high speed with positioning accuracy is required.

  From the viewpoint of positioning performance and throughput, so-called flat motors (also called flat motors or linear motors) that generate thrust by electromagnetic driving force are linear in the relationship between the current driving the stage and the thrust up to a high band. Excellent controllability in terms of showing the relationship, ensuring stable positioning accuracy in a wide control band, easy downsizing with a simple configuration, and planar motor and planar direction Attention has been drawn to the fact that multi-stage positioning by driving (positioning and attitude control) with six degrees of freedom is possible by combining them so as to generate thrust corresponding to each degree of freedom.

As the above-described prior art, for example, there is one shown in Patent Document 1 below.
Japanese Patent Laid-Open No. 2004-254489

  However, in the case of a linear motor that uses a mover as the part that has a permanent magnet, multiple permanent magnets (complementary poles) that are installed to efficiently collect magnetic fields around the permanent magnet (main pole) that mainly generates thrust are arranged. As a result, there is a problem that the mass of the permanent magnet constituting the mover increases. When the mass of the mover increases, when the mover is driven at high acceleration / deceleration, a large current must be passed through the coil, and the amount of heat generated by the coil also increases. As the current flowing through the coil increases, the power consumption increases, so the motor driver that drives the linear motor is also enlarged. The cost will increase accordingly.

  Further, when the heat generated on the stator side is transmitted to the stage due to an increase in the amount of heat generated by the coil, the stage thermally expands, for example, the wafer pattern on which the circuit pattern is printed from the position measured by a laser interferometer or the like. There is a problem that the distance to the exposure region changes due to thermal expansion, and the positioning accuracy of the exposure region is lowered. Furthermore, when the temperature of the air on the stator rises due to the heat generated by the coil, the atmospheric pressure in that region changes. As a result, the laser beam wavelength of the laser interferometer used to detect the stage position fluctuates as it passes over the stator, and the laser interferometer may not be able to accurately detect the stage position. .

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a linear motor that can reduce the weight of the mover in the linear motor and reduce the heat generation of the coil.

  Alternatively, in an exposure apparatus that employs a linear motor as a stage driving mechanism, an object is to provide an exposure technique that suppresses the influence of the amount of heat generated by a coil and realizes positioning of an exposure area with high accuracy.

  In order to achieve the above object, a linear motor according to the present invention mainly has the following configuration.

That is, it has a mover in which a main pole permanent magnet, an auxiliary pole permanent magnet that collects a magnetic field around the main pole permanent magnet, and a stator coil facing the main pole permanent magnet, The linear motor that generates thrust based on the control current between the pole permanent magnet and the stator coil is
A main pole permanent magnet having a first permanent magnet thickness, disposed in a plane facing the stator coil;
An auxiliary pole permanent magnet having a second permanent magnet thickness, disposed opposite to the stator coil and arranged in the same plane on which the main pole permanent magnet is arranged,
The first and second permanent magnet thicknesses satisfy the following relationship: first permanent magnet thickness> second permanent magnet thickness.

  According to the present invention, it is possible to provide a linear motor that is excellent in positioning accuracy and high-speed driving performance by reducing the heat of the coil by reducing the weight of the mover.

  Alternatively, in an exposure apparatus that employs such a linear motor as a stage drive mechanism, it is possible to suppress the influence of the amount of heat generated by the coil and to achieve highly accurate exposure region positioning.

(First embodiment)
A first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an overall configuration of the linear motor according to the first embodiment, and FIG. 1A is a diagram illustrating a state in which the linear motor in the XY plane is viewed from the Z direction. On the stator 100 including the coils 116a, 116b..., A stage 110 that functions as a mover of the linear motor is disposed. A mechanism (not shown) for holding the wafer is mounted on the stage 110. With the wafer held, the stage 110 is translated and rotated in the XY direction or the Z direction to position the wafer at a predetermined position and posture. Is possible.

  The position and orientation of the stage 110 are, for example, a position measurement unit such as a laser interferometer attached to a certain measurement standard (1320 (ac), orientation measurement unit (1330 (ac) (see FIG. 13)). It is possible to measure with.

  FIG. 1B is a diagram illustrating a state in which the linear motor is viewed from the side (the XZ plane is in the Y-axis direction). The stage 110 (hereinafter also referred to as “mover unit”) includes a rectangular parallelepiped top plate 112 and permanent magnet arrays arranged at positions facing the coil array 116a on the stator 100 side. 114.

  The stator 100 includes a base 118 and a laminated coil array 116 including six layers of coil arrays fixed on the base 118. Here, as shown in FIG. 1A and FIG. 2, the laminated coil array 116 includes a coil array arranged so that the longitudinal direction of the coil is parallel to the Y-axis direction, and the longitudinal direction of the coil is the X-axis. Six coil arrays arranged so as to be parallel to the direction are alternately stacked. The force generated by each coil array is a propulsive force of at least one degree of freedom of the stage 110, and the position and posture of the stage 110 are controlled by the propulsive force of six degrees of freedom by stacking the six coil arrays. .

<Description of control system>
FIG. 13 is a block diagram of a control circuit for controlling the driving of the stage 110. The current control unit 1300 supplies a control current for controlling the position and orientation by driving the stage 110 to the A-phase coil (1302). ), -A phase coil (1304), B phase coil (1306), and -B phase coil (1308). The current control unit 1300 includes a control command value 1370 output from the device control unit 1310 that controls the entire device, and position detection information 1350 (ac) of the stage 110 detected by the position measurement unit 1320 (ac). ) And attitude information 1360 (ac) of the stage 110 detected by the attitude measuring unit 1330 (ac), a control current 1380 (ad) is applied to the coil selected in each coil array. Can be output. In FIG. 13, for the sake of simplicity, only the control current for one coil array is shown. The current control unit 1300 generates a control current for each coil in six coil arrays, and a coil unit (for example, an A-phase coil and a -B-phase coil (coil 7 and coil in FIG. 4) formed by a combination of adjacent coils. The control current is applied to the -A phase coil and the B phase coil (the combination of the coil 9 and the coil 10 in FIG. 4). Thereby, the current control unit 1300 generates a thrust in the translation direction (X, Y, Z direction) and a thrust in the rotation direction (ωx, ωy, ωz direction), and controls the position and posture of the stage 110.

<Structure of stator>
FIG. 1B is a diagram illustrating a state in which the linear motor is viewed from the XZ plane. The stator 100 includes a base 118 and a laminated coil array 116 in which six coil arrays are stacked. FIG. 2 shows an enlarged view of the laminated coil array 116 while focusing on the A portion showing the stator 100. Referring to FIG. 2, the coil arrays 1, 3, and 5 are arranged so that the longitudinal direction of the coil is parallel to the Y-axis direction, and the coils are arranged so that the longitudinal direction of the coil is parallel to the X-axis direction. Rows 2, 4, and 6 are alternately arranged.

  In FIG. 2, the coil array 1 is a coil array for driving the stage 110 in the X-axis direction, and the coil array 2 is disposed under the coil array 1 via an insulating sheet (not shown). The coil array 2 is a coil array for driving the stage 110 in the Y direction, and the coil array 3 is disposed under the coil array 2 via an insulating sheet. The coil array 3 is a coil array for driving the stage 110 in the Z direction, and the coil array 4 is disposed under the coil array 3 via an insulating sheet.

  The coil arrays 1 to 3 are used to generate a thrust force for driving the stage 110 in the translation direction (X, Y, Z axis directions).

  Next, the coil array 4 is a coil array for rotationally driving the stage 110 around the Z axis, and the coil array 5 is disposed under the coil array 4 via an insulating sheet. The coil array 5 is a coil array for rotationally driving the stage 110 around the Y axis, and the coil array 6 is disposed under the coil array 5 via an insulating sheet. The coil array 6 is a coil array for rotationally driving the stage 110 around the X axis, and the base member 100 is disposed under the coil array 6 via an insulating sheet.

  The coil arrays 4 to 6 are used to generate a thrust force for driving the stage 110 in the rotation direction (ωz, ωy, ωx).

  Note that the configuration of the laminated coil 116 that uses one coil array as a drive source for generating thrust for realizing one degree of freedom of movement is not limited to that shown in FIG. As for the stacking order, the coil arrays 1, 3, and 5 may be used for driving in the rotational direction, and the coil arrays 2, 4, and 6 may be configured to drive in the translation direction.

<Description of stage 110>
FIG. 3 is a diagram showing a configuration of the permanent magnet row 114 provided on the mover 110. A permanent magnet row 114 composed of a plurality of permanent magnets (115a to f in FIG. 3B) is formed below the top plate 112. The permanent magnet array 114 includes a magnet magnetized upward in the Z direction, a magnet magnetized downward in the Z direction (corresponding to 115a and 115b in FIG. 3B), and a 45 degree direction with respect to the X direction. , 135 degrees direction, −135 degrees direction, −45 degrees direction magnets (corresponding to 115c, d, e, and f in FIG. 3B) are composed of six types of permanent magnets.

  FIG. 3B is a diagram illustrating a state in which the stage 110 is viewed from the back side (the surface side on which the permanent magnet row 114 is disposed). The permanent magnet row 114 includes a permanent magnet (115b) having a polarity in the direction facing the stator 100 (-Z direction) and a permanent magnet (115a) having a polarity in the opposite direction (+ Z direction) Poles) and permanent magnets (115c, 115d, 115e, 115f) (referred to as “complementary poles”) arranged so that their polar directions repel each other between them. . A permanent magnet having a polarity in the direction facing the stator 100 (−Z direction) is indicated by writing “•” in “○” (115b), and a permanent magnet having a polarity in the opposite direction (+ Z direction). “X” is written in “○” (115a). Similarly, the polarity direction of the complementary pole is shown using arrows.

  The permanent magnets (115a to 115f) are regularly arranged with a period L in the X direction, the X direction, and the Y direction. Since the permanent magnets are regularly arranged in this manner, the magnetic field is efficiently collected on the stator 100 side. The Z component of this magnetic field is distributed so as to be a pseudo sine wave with a period L in the X and Y directions, and has a peak under the main pole. Similarly, the X component and Y component of the magnetic field are distributed so as to be substantially sinusoidal with a period L in the X and Y directions, and have a peak under the complementary pole.

<Description of driving method>
FIG. 4 is a diagram illustrating a state where the back side of the stage 110 (the surface side on which the permanent magnet row 114 is disposed) is viewed from the coil row disposed in parallel with the Y-axis direction. The interval between the longitudinal portions of the coil units constituting the coil array is a magnet period L / 2. Moreover, the space | interval of adjacent coil units is arrange | positioned at (3/4) * L period. That is, with respect to the magnet period L, the phases of the adjacent coils are shifted by 270.

  In addition, in the state of FIG. 4, the coils on the stator side 100 side that overlap the permanent magnet row 114 on the stage 110 side are numbered 1 to 16. Here, the control currents flowing through the coils are the following four groups corresponding to the positional relationship between the coils (1 to 16) and the permanent magnet array 114, and groups of A-phase coils (coils 3, 7, 11, 15). -A phase coil group (coils 5, 9, 13), B phase coil group (coils 2, 6, 10, 14), -B phase coil group (coils 4, 8, 12, 16) ).

  Here, with respect to the two-phase control currents of the A-phase and the B-phase, the negative-direction control currents of the -A-phase and the -B-phase flow if a control current in the opposite direction to the control currents of the A-phase and the B-phase flows A thrust in the same direction as the A-phase and B-phase control currents is generated for the stage 110. When the A-phase and B-phase control currents are determined, the -A-phase and -B-phase currents are automatically determined. The Z component of the magnetic field is distributed so as to be a pseudo sine wave with a period L in the X and Y directions and has a peak below the main pole. Similarly, the X and Y components of this magnetic field are also in the X direction. , Distributed in the Y direction so as to be almost sinusoidal with a period L, and has a peak under the complementary pole. Therefore, if the sine wave control is performed so that a current having the same phase as the magnetic flux density distribution in the vertical direction flows through each coil, the position Regardless, a thrust proportional to the sine wave amplitude of the current is generated.

  When a unit current (1 [A]) is passed through the coil of each phase in a state where the position of the stage 110 shown in FIG. 4 is set to X = 0 and the position of the stage 110 is changed by X, the horizontal direction acting on the stage 110 will be described. The thrust f_h is expressed as follows.

A phase coil: f_h = HDF × cos ((X / L) × 2 × π) (1)
B phase coil: f_h = HDF × sin ((X / L) × 2 × π) (2)
-Phase A coil: Thrust opposite to phase A (3)
-B phase coil: Thrust reverse to B phase (4)
Here, “HDF” represents a horizontal thrust (horizontal thrust constant) acting on the stage 110 when the stage 110 passes a current of 1 [A] through the A-phase coil at the position of X = 0. .

At this time, if the following current (formulas (5) to (8)) is passed through the coils of each phase, sin ² ((X / L) × 2 × π) + cos ² ((X / L) × 2 × π) ) = 1, a uniform thrust can be applied regardless of the value of X.

Phase A current: IA = Ic × cos ((X / L) × 2 × π) (5)
B phase current: IB = Ic × sin ((X / L) × 2 × π) (6)
-A phase has a current opposite to that of phase A (7)
-Current in B phase is opposite to B phase (8)
However, Ic (the maximum value of the current flowing through one coil) is arbitrary.

  The vertical thrust f_v acting on the stage 110 when a unit current (1 [A]) is passed through the coils of each phase is expressed as follows.

A phase coil: f_v = VDF × sin ((X / L) × 2 × π) (9)
B phase coil: f_v = VDF × cos ((X / L) × 2 × π) (10)
-Phase A coil: Thrust in phase opposite to phase A (11)
-B phase coil: Thrust of B phase and opposite phase (12)
However, VDF represents the vertical thrust (vertical thrust constant) acting on the stage when a current of 1 [A] is passed through the B-phase coil at the position where X = 0.

  When it is desired to apply a thrust in the Z direction to the stage 110, a uniform thrust is applied regardless of the value of X when the following currents (Equations (13) to (16)) are passed through the coils of each phase. Can do.

Phase A current: IA = Ic × cos ((X / L) × 2 × π + (π / 2))
= Ic × sin ((X / L) × 2 × π) (13)
B phase current: IB = Ic × sin ((X / L) × 2 × π + (π / 2))
= Ic × cos ((X / L) × 2 × π) (14)
-A phase has a current opposite to that of phase A (15)
-Current in B phase opposite to B phase (16)
However, Ic (the maximum value of the current flowing through one coil) is arbitrary.

  When the stage 110 is shifted to the (X +) plus side from the position of X = 0 (0 <X <(3/4) × L), when the stage 110 is driven in the X direction, the current control unit 1300 In the coil array 1, for example, a control current that applies a thrust in the horizontal direction to the stage 110 may be supplied using the coil units (7, 8), (9, 10) and the coil units (11, 12).

  Under the control of the apparatus control unit 1310, the current control unit 1300 can perform switching control of the coil unit in order to drive the stage 110 in the translation direction and the rotation direction according to the position of the stage 110. The current control unit 1300 selects and switches the coil unit in the coil array, and drives each of the coils in order to drive the stage 110 in the translation direction and the rotation direction for each of the coil arrays 1 to 6 shown in FIG. It is possible to control the stage 110 to a predetermined position and posture by controlling the application of the control current to the unit.

  When driving the stage 110 in the Z direction, the current control unit 1300, for example, includes the coil units (6, 7), (8, 9), (10, 11) and the coil units (12, 13) of the coil array 3. The control current that applies the thrust in the vertical direction to the stage may be sent using

  When applying a rotational force around the Y axis to the stage, the current control unit 1300, for example, includes the coil units (6, 7), (8, 9) and the coil units (10, 11) in the coil array 5; Using (12, 13), a control current may be passed through the stage 110 so that vertical thrusts in opposite directions act on each other.

  When the stage position change X is in the range of (3/4) × L ≦ X <2 × (3/4) × L, the coil unit described above is changed to a coil unit having a higher number. It only has to be switched. For example, in this case, the current control unit 1300 can switch the coil unit by switching the coil unit (3, 4) to (4, 5) and the coil unit (6, 7) to (7, 8). Is possible.

  Furthermore, even when the stage 110 is driven in a range of 2 × (3/4) × L or more, the current control unit 1300 can perform similar switching of the coil units. In the region where the coil unit is disposed on the stator 100 side, the current control unit 1300 generates a thrust for driving the stage 110 by applying a control current for driving the stage 110 to the coil unit. It is possible to make it.

  Further, when the stage 110 is shifted to the minus side from the position of X = 0 (− (3/4) × L <X <0), when the stage 110 is driven in the X direction, the current control unit 1300 In the coil array 1, for example, a control current for applying a horizontal thrust to the stage 110 may be supplied using the coil units (6, 7), (8, 9) and the coils (10, 11).

  Furthermore, when the change X in the position of the stage 110 is in the range of −2 × (3/4) × L <X ≦ − (3/4) × L, the current control unit 1300 is one than the coil unit described above. It is possible to switch the coil unit by switching to the coil unit having the lower number. For example, the current control unit 1300 may switch the coils (2, 3) to (1, 2) and the coils (5, 6) to (4, 5).

  The current control unit 1300 can perform the same coil switching even when the stage 110 is driven in a minus direction range further than −2 × (3/4) × L. Even when moving in the minus direction, if the coil unit is disposed in the stator 100 side, the current control unit 1300 applies a control current for driving the stage 110 to the coil unit, and the stage It is possible to generate a thrust for driving 110.

  FIG. 5 is a diagram showing a state in which the back side of the stage 110 (the surface side on which the permanent magnet row 114 is arranged) is viewed from the coil row arranged in parallel with the X-axis direction. The interval between the longitudinal portions of the coils constituting the coil array is the magnet cycle L / 2 as in the configuration described with reference to FIG. 4, and the interval between adjacent coils is (3/4) × L cycle. ing. In the state of FIG. 5, the coils on the stator 100 side that overlap with the permanent magnet row 114 on the stage 110 side are numbered 1 to 16 as in FIG. The current control unit 1300 determines the coil number to which the control current is applied according to the position of the stage 110 and the driving direction (translation direction and rotation direction), performs switching, and controls the A-phase and B-phase control currents to the coil. By applying to the unit, the thrust in the Y direction (coil array 2), the rotational force around the Z axis (coil array 4), and the rotational force around the X axis (coil array 6) are applied to the stage 110 as in FIG. be able to.

<Description of permanent magnet array 114>
FIG. 6 is an enlarged view of FIG. 3A, and is a view showing a cross section of the stage 110 broken at the AA-AA portion in FIG. 3B. In the same figure, 112 is a top plate, 115a and 115b are permanent magnets of the main pole constituting the permanent magnet row 114, 115d and 115f are permanent magnets of the complementary pole constituting the permanent magnet row 114, Each has the same polarity as the permanent magnets 115a, 115b, 115d, and 115f described in FIG.

  A mover (stage 110) in which a main pole permanent magnet (115a and 115b) and a supplementary pole permanent magnet (115d and 115f) that collects a magnetic field around the main pole permanent magnet are disposed, and the main pole permanent magnet is opposed. A linear motor having a stator coil and generating a thrust based on a control current between the main pole permanent magnet and the stator coil is a stator coil facing the mover (for example, 116a and 116b in FIG. 1). A linear motor including a control circuit (FIG. 13) that controls the driving and positioning of the mover by generating a thrust between the first permanent magnet and the first permanent magnet. A main pole permanent magnet having a thickness (hereinafter referred to as “main pole magnet thickness (t1)”) and a stator coil are disposed on the same plane where the main pole permanent magnet is disposed, facing the stator coil. Permanent magnet thickness (hereinafter referred to as “magnet of complementary pole” A first permanent magnet thickness> the second permanent magnet thickness (the thickness (t2) "). It satisfies t1> t2).

  Specifically, in FIG. 6, the thickness of the permanent magnet of the main pole (115a, 115b) is t1, and the thickness of the permanent magnet of the auxiliary pole (115d, 115f) is t2. The relationship between the thicknesses of the permanent magnets is the same as in FIG. 3, where the magnet thicknesses of the main poles (115a, 115b) are t1, and the magnet thicknesses of the complementary poles (115c, 115d, 115e, 115f) are t2. To do. 3 and 6, a relationship of t1> t2 is established between the magnet thickness (t1) of the main pole and the magnet thickness (t2) of the complementary pole.

  In the permanent magnet array 114 in the stage 110, the surface of the permanent magnets (115a, 115b) of the main pole facing the stator 100 and the permanent magnets of the complementary poles (115c, 115d, 115e, 115f) face the stator 100. The plane is assumed to be arranged in the XY plane so that no step is generated (FIGS. 3 and 6). The main and auxiliary permanent magnets are arranged so that no step is generated on the surface facing the stator 100, so that the main electrode (115 a) is interposed between the auxiliary electrode (115 d, 115 f) and the top plate 112. 115b), a gap 117 corresponding to the difference in thickness (= t1-t2) is formed.

  In the configuration of the permanent magnet array 114, the main pole mainly generates a magnetic field that exerts thrust on the stage 110, and the auxiliary pole assists in efficiently collecting the magnetic field that exerts thrust on the stage 110 on the stator side. Permanent magnet that plays a central role. In the arrangement of the permanent magnets of the main pole and the complementary pole shown in FIG. 3, the number of complementary poles is provided nearly twice as many as the number of main poles. If the magnet thickness (t1) of the main pole and the magnet thickness (t2) of the complementary pole are the same (t1 = t2) as in the conventional flat motor, the mass of the stage 110 corresponds to (t1-t2). Since the load increases as the mass), the current control unit 1300 needs to control current to flow a large current to each layer coil in order to move the stage 110 at high acceleration / deceleration, which is generated in each layer coil. Heat generation increases and power consumption increases.

  On the other hand, if the magnet thickness t2 of the supplementary pole is made thinner than the magnet thickness t1 of the main pole, the thrust constant decreases accordingly, but the permanent magnet of the supplementary pole is smaller than the permanent magnet of the main pole. Since the number is nearly double, the effect of reducing the stage mass due to the reduction in the magnet thickness of the auxiliary pole is greater than the reduction in thrust.

  The number of coil units (combination of adjacent coils) used when driving the stage 110 is U, and the horizontal acceleration required for the stage 110 is α.

  In the case of t1 = t2, the mass of the stage 110 is M, the horizontal thrust constant is HDF, and the maximum value of the current passed through one coil unit is Ic.

  In the case of t1> t2, the mass of the stage 110 is M ′, the horizontal thrust constant is HDF ′, and the maximum value of the current passed through one coil unit is Ic ′.

  When the reduction rate of the thrust constant due to the reduction of the thickness of the permanent magnet of the supplementary pole is k and the reduction rate of the mass is K, the relationship between the horizontal direction thrust constants is HDF ′ = HDF (1-k), and the stage The mass relationship of 110 is M ′ = M (1−K).

  When the horizontal thrust in one coil unit (combination of adjacent coils (for example, A phase coil and -B phase coil)) acting on the stage 110 is calculated by the equations (1) to (8), the equation (17) It becomes like this.

(1) Formula x (5) Formula + (2) Formula x (6) Formula = Ic · HDF (17)
Ic: Maximum value of current flowing through one coil HDF: Horizontal thrust constant.

  Then, in order to drive the stage 110 from the relationship of (17), the horizontal thrust when using a plurality of coil units U is U · Ic · HDF, and the thickness of the permanent magnet of the complementary pole is reduced. The thrust in this case is U · Ic ′ · HDF ′. As the equations of motion when using a plurality of coil units U, the relationships of equations (18) and (19) are established.

When t1 = t2: U · Ic · HDF = M · α (18)
When t1> t2: U · Ic ′ · HDF ′ = M ′ · α (19)
When Ic ′ is expressed by Ic, k, K, the relationship of (20) is established.

Ic ′ = (1-K) / (1-k) × Ic (20)
In a configuration in which the thickness of the permanent magnets (115d, f, etc.) of the auxiliary pole is reduced, the maximum current Ic ′ flowing through one coil is the current when the thickness of the permanent magnet of the auxiliary pole and the main pole is the same. In order to be smaller than the maximum value Ic (Ic ′ <Ic), the relationship of mass reduction rate (K)> thrust constant reduction rate (k) may be satisfied.

  The second permanent magnet thickness (t2) is a reduction in thrust acting on the mover (stage 110) based on the difference between the first permanent magnet thickness (t1) and the second permanent magnet thickness (t2). The relationship that the mass reduction rate (mass reduction rate (K)) of the mover is larger than the rate (thrust constant reduction rate (k)) is satisfied. That is, if the thickness of the magnet t2 is set so that the ratio (K) in which the mass of the stage decreases is larger than the ratio (k) in which the thrust acting on the stage 110 decreases, the stage 110 becomes t1. = The control current to be supplied to the coil when driving at the same acceleration as that when driving at t2 can be reduced.

  When Joule heat generated in the coil unit used when driving the stage 110 is Q, U is the number of coil units to be used, Ic is the maximum value of current flowing through one coil, and R is the resistance of one coil, The relationship of equation (21) is established.

Q = U · Ic ² · R (21)
When the maximum value (Ic) of the current flowing through one coil is reduced, the Joule heat (Q) generated in the coil unit is also reduced. That is, if the thickness of the permanent magnet t2 of the supplementary pole is set so that the ratio (K) at which the mass of the stage decreases is larger than the ratio (k) at which the thrust acting on the stage 110 decreases, Joule heat (Q) generated in the coil unit when the stage 110 is driven in the horizontal direction at the same acceleration as when t1 = t2 can be reduced.

  That is, when the thickness of the permanent magnet of the supplemental pole satisfying the relationship of mass reduction rate (K)> thrust constant reduction rate (k) is set to t2, it is generated in the coil unit without reducing the horizontal acceleration. Joule heat can be reduced.

  The above description is not limited to the thrust in the horizontal direction, but also holds when the thrust is generated in the vertical direction or when the thrust is generated in the rotational direction.

  According to the present embodiment, it is possible to provide a linear motor that is excellent in positioning accuracy and high-speed drive performance by reducing the heat generation of the coil by reducing the weight of the mover.

  Further, in addition to the reduction of Joule heat (Q), the gap portion 117 can suppress the Joule heat from being transmitted to the top plate 112 and can cool the top plate 112. When the top plate 112 is heated, for example, a mechanism for holding a wafer (not shown) provided on the top plate 112 is heated, and the gap portion 117 is deformed due to the influence of the heat. Can be eliminated.

  In addition, it is possible to suppress the occurrence of position measurement errors due to the thermal expansion and deformation of the top plate 112.

  Even if the adhesion area of the permanent magnet is reduced due to the formation of the gap 117 between the auxiliary permanent magnets (115d, 115f) and the top plate (112) described in the present embodiment, A member made of a lightweight material different from the permanent magnet and the permanent magnet of the supplementary pole can be provided in the gap 117 to prevent the adhesive strength from being lowered.

  As a lightweight material having a smaller density than the permanent magnets (115a to 115f) provided in the gap 117, for example, a porous material such as ceramics, a honeycomb member, a hollow member, or the like can be used.

  With this configuration, it is possible to reduce the weight of the (movable element) 110 in the linear motor and to prevent the adhesive strength of the permanent magnet of the complementary pole from decreasing.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 7 is a diagram showing a stage system in which a linear motor 119 movable in the X direction and a linear motor 120 movable in the Y direction are combined, and the stage 701 is driven two-dimensionally to position in the XY plane. is there. As the control circuit for driving the linear motors 119 and 120 and positioning them at a predetermined position, the control circuit of FIG. 13 described in the first embodiment can be used.

  FIG. 8 is a cross-sectional view illustrating the structure of the mover and the stator in the linear motor 119, and is a view of the (CC-CC)-(BB-BB) cross section of FIG. 7 as viewed in the direction of the arrow. . It is assumed that the same arrangement as that described in the first embodiment is adopted for the arrangement of the permanent magnets constituting the mover 122 in the second embodiment.

  In the mover 122, the permanent magnets (121a, 121b) of the main pole are arranged so that the polarities are alternately different via the permanent magnets (121c, 121d) of the complementary pole. The complementary permanent magnets (121c, 121d) disposed between the permanent magnets of the main pole have polarities in the X direction and the -X direction, and the respective polarities sandwich the permanent magnet of the main pole and face each other. Are arranged to be.

  The main pole permanent magnets (121 a, 121 b) and the complementary pole permanent magnets (121 c, 121 d) are arranged so that there is no step on the surface facing the stator 123.

  126 is a top plate made of a magnetic or non-magnetic material, and the permanent magnets (121a, 121b) of the main pole are fixed in a state of being attached to the top plate 126. As in the first embodiment, the thickness of the permanent magnet in this embodiment is t1, where the thickness of the main pole permanent magnet (121a, 121b in FIG. 8) is t1, and the thickness of the permanent magnet (FIG. 8). 121c and 121d) are assumed to be t2, and the relationship between both thicknesses is that t1> t2. Further, due to the difference in thickness of the permanent magnets, a structure in which a gap portion 125 is provided between the complementary permanent magnets (121c, 121d) and the top plate 126 is employed.

  FIG. 9 is a view showing a modification of FIG. 8 showing the relationship between the mover and the stator constituting the linear motor. In the configuration of FIG. 9, the movable element 132 is sandwiched between the stator 133 and the upper and lower parts. Also in the configuration of FIG. 9, the same configuration as that described in the first embodiment is adopted for the arrangement of the permanent magnets configuring the mover 132.

  In the mover 132 in FIG. 9, the permanent magnets (131a, 131b) of the main pole are arranged so that the polarities are alternately different via the permanent magnets (131c, 131d) of the supplementary pole. The complementary permanent magnets (131c, 131d) arranged between the permanent magnets of the main pole have polarities in the X direction and the -X direction, and the respective polarities sandwich the main permanent magnet between them. Are arranged to be. The main pole permanent magnets (131 a, 131 b) and the complementary pole permanent magnets (131 c, 131 d) are arranged so that there is no step on the surface facing the stator 133.

  Reference numeral 136 denotes a top plate made of a magnetic or non-magnetic material, and the permanent magnets (131 a and 131 b) of the main pole are fixed while being attached to the top plate 126. The thickness of the permanent magnet in FIG. 9 is also the same as that described in the first embodiment, where the thickness of the permanent magnet of the main pole (131a, 131b in FIG. 9) is t1, and the permanent magnet of the complementary pole (FIG. 9). It is assumed that the thickness of 131c, 131d) is t2, and the relationship between both thicknesses is t1> t2. Further, due to the difference in thickness of the permanent magnets, a structure in which a gap portion 135 is provided between the complementary permanent magnets (131 c and 131 d) and the top plate 136 is employed.

  In both FIG. 8 and FIG. 9, the permanent magnets of the auxiliary poles are arranged at both ends of the permanent magnet of the main pole in the mover, and the number of permanent magnets of the auxiliary poles is larger than that of the main pole.

  Accordingly, even in a linear motor that can move in one dimension, the thickness t2 of the permanent magnet of the supplementary pole is less than the rate (k) at which the thrust acting on the mover 122 is reduced (K). The linear motor driven in the one-dimensional direction can obtain the same effect as that of the linear motor movable in three dimensions.

  According to the present embodiment, it is possible to provide a linear motor that is excellent in positioning accuracy and high-speed drive performance by reducing the heat generation of the coil by reducing the weight of the mover.

  Further, by setting the thickness t2 of the permanent magnet of the supplementary pole so as to satisfy the above-described relationship, when driving at the same acceleration as when driving the permanent magnet with the thickness t1 = t2, the coil unit The generated Joule heat (Q) can also be reduced. When the thickness of the permanent magnet of the auxiliary pole satisfying the relationship of mass reduction rate (K)> thrust constant reduction rate (k) is set to t2, Joule heat generated in the coil unit without reducing the horizontal acceleration. Can be reduced.

  In addition, the adhesion area of a permanent magnet reduces by the space | gap part (125, 135) of the permanent magnet (121c, d, 131c, d) of an auxiliary pole demonstrated in this embodiment, and a top plate (126, 136). Even when the adhesive strength decreases, the thickness of the permanent magnet of the supplementary pole is such that the rate of decrease in the stage mass (K) is greater than the rate of decrease in the thrust acting on the mover (k). It is also possible to arrange a light material having a lower density than the permanent magnet for the purpose of setting the length t2 and increasing the bonding area of the permanent magnet. In this case, as the material having a low density, for example, a porous material such as ceramics, a honeycomb member, a hollow member, or the like can be used.

(Third embodiment)
Next, a third embodiment according to the present invention will be described with reference to FIG. FIG. 10 is a diagram showing an example in which the linear motor according to the first or second embodiment is applied to an exposure apparatus. As shown in FIG. 10, the exposure apparatus 1000 includes an illumination device 201, a reticle stage 202 on which a reticle is mounted, a projection optical system 203, and a wafer stage 204 on which a wafer is mounted. The exposure apparatus 1000 projects and exposes a circuit pattern formed on a reticle (not shown) onto a wafer, and is a step-and-repeat reduction projection exposure apparatus or a step-and-scan scanning projection exposure apparatus. It may be.

The illumination device 201 illuminates a reticle on which a circuit pattern is formed, and includes a light source unit and an illumination optical system. The light source unit uses, for example, a laser as a light source. As the laser to be used, for example, an ArF excimer laser with a wavelength of about 193 nm, a KrF excimer laser with a wavelength of about 248 nm, an F ₂ excimer laser with a wavelength of about 153 nm can be used, but the type of laser is not limited to an excimer laser. For example, a YAG laser may be used, and the number of lasers is not limited.

  When a laser is used as the light source, it is preferable to use a light beam shaping optical system that shapes the parallel light beam from the laser light source into a desired beam shape and an incoherent optical system that makes the coherent laser light beam incoherent. The light source that can be used in the light source unit is not limited to a laser, and one or a plurality of lamps such as a mercury lamp and a xenon lamp can be used.

  The illumination optical system is an optical system that illuminates the reticle, and includes a lens, a mirror, a light integrator, a diaphragm, and the like.

  The projection optical system 203 includes an optical system composed only of a plurality of lens elements, an optical system having at least one concave mirror (catadioptric optical system), a plurality of lens elements, and at least one kinoform. An optical system having a diffractive optical element, an all-mirror optical system, or the like can be used. Such an exposure apparatus can be used for manufacturing a semiconductor device such as a semiconductor integrated circuit or a device on which a fine pattern such as a micromachine or a thin film magnetic head is formed.

  The linear motor described in the first or second embodiment can be used as the driving mechanism for the reticle stage 202 for mounting the reticle or the wafer stage 204 for mounting the wafer. By adopting a drive mechanism for the exposure apparatus, it is possible to reduce the weight of the stage serving as the movable part, and the relationship is as follows: the thickness t1 of the permanent magnet of the main pole> the thickness t2 of the permanent magnet of the complementary pole. If the thickness (t2) of the permanent magnet of the auxiliary pole is set so that the rate (K) at which the mass of the stage decreases is greater than the rate (k) at which the thrust acting on the stage decreases, t1 = Joule heat (Q) generated in the coil unit when driving at the same acceleration as when driving at t2 can be reduced.

  Further, in addition to the reduction of Joule heat (Q), the gap portion can suppress the Joule heat from being transmitted to the top plate, and can cool the top plate. When the top plate is heated, for example, a reticle or wafer holding mechanism (not shown) provided on the top plate is heated, and the gap portion is deformed due to the influence of the heat. The influence on the wafer can be suppressed.

  In addition, it is possible to suppress the occurrence of position measurement errors in the exposure region due to the top plate being thermally expanded and deformed. Further, by suppressing the change in the atmospheric pressure due to the temperature change in the exposure region, the position of the laser interferometer in the position measurement unit (1320a, b, c: see FIG. 13) and the posture measurement unit (1330a, b, c) is reduced. It becomes possible to suppress the fluctuation of the wavelength and realize the positioning of the exposure area with high accuracy.

(Example of device manufacturing method)
Next, a semiconductor device manufacturing process using the exposure apparatus of the third embodiment will be described. FIG. 11 is a diagram showing a flow of an entire manufacturing process of a semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask fabrication), a mask is fabricated based on the designed circuit pattern.

  On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by using the above-described exposure apparatus and lithography technology using the above-described mask and wafer. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and is an assembly process (dicing, bonding), packaging process (chip encapsulation), etc. Process. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes, and is shipped in Step 7.

  As shown in FIG. 12, the wafer process in step 4 includes an oxidation step (step 11) for oxidizing the wafer surface, a CVD step (step 12) for forming an insulating film on the wafer surface, and depositing electrodes on the wafer. An electrode forming step to be formed (step 13), an ion implantation step for implanting ions into the wafer (step 14), a resist processing step for applying a photosensitive agent to the wafer (step 15), and a resist pattern processing step (step 15) Step 15) An exposure step (Step 16) for transferring to the wafer after the development, a development step (Step 17) for developing the wafer exposed in the exposure step, and an etching step (Step 18) for scraping off portions other than the resist image developed in the development step. Is no longer needed after etching And having a resist stripping step (step 19) to remove the resist. By repeating these steps, multiple circuit patterns can be formed on the wafer.

It is a figure which shows the whole structure of the linear motor concerning 1st Embodiment. It is the figure which expanded and illustrated the laminated coil row | line | column 116 in 1st Embodiment. It is a figure which shows the structure of the permanent magnet row | line | column 114 provided in the needle | mover 110. FIG. It is a figure which shows the state which looked at the back side (surface side in which the permanent magnet row | line | column 114 is arrange | positioned) of the stage 110 from the coil row | line | column arrange | positioned in parallel with the Y-axis direction. It is a figure which shows the state which looked at the back side (surface side in which the permanent magnet row | line | column 114 is arrange | positioned) of the stage 110 from the coil row | line | column arrange | positioned in parallel with the X-axis direction. FIG. 3B is a diagram showing a cross section of the stage 110 broken at the AA-AA portion in FIG. It is a figure which shows the stage system which drives the stage 701 two-dimensionally and positions in an XY plane. It is sectional drawing explaining the structure of the needle | mover and stator in a linear motor. It is a figure which shows the modification of FIG. 8 which shows the relationship between the needle | mover and stator which comprise a linear motor. It is a figure which shows the example which applied the linear motor concerning 1st or 2nd embodiment to exposure apparatus. It is a figure which shows the flow of the whole manufacturing process of a semiconductor device. It is a figure explaining the wafer process of step 4 in detail. 2 is a block diagram of a control circuit for controlling the driving of a stage 110. FIG.

Claims (7)

A main pole permanent magnet, a complementary pole permanent magnet that collects a magnetic field around the main pole permanent magnet, a mover, and a stator coil facing the main pole permanent magnet, the main pole permanent A linear motor that generates a thrust based on a control current between a magnet and a stator coil,
A main pole permanent magnet having a first permanent magnet thickness, disposed in a plane facing the stator coil;
An auxiliary pole permanent magnet having a second permanent magnet thickness, disposed opposite to the stator coil and arranged in the same plane on which the main pole permanent magnet is arranged,
The linear motor according to claim 1, wherein the thicknesses of the first and second permanent magnets satisfy the following relationship: first permanent magnet thickness> second permanent magnet thickness. The thickness of the second permanent magnet is smaller than the rate of reduction of the thrust acting on the mover due to the difference between the thickness of the first permanent magnet and the thickness of the second permanent magnet. The linear motor according to claim 1, wherein a relationship in which a decrease rate of the linear motor is increased is satisfied. The linear motor according to claim 1, wherein a gap is formed in a region corresponding to a difference between the first permanent magnet thickness and the second permanent magnet thickness. The region corresponding to the difference between the first permanent magnet thickness and the second permanent magnet thickness is provided with a member having a material different from that of the main pole permanent magnet and the complementary permanent magnet. The linear motor according to claim 1 or 2. The linear motor according to claim 4, wherein the different material includes a porous material, a honeycomb member, and a hollow member. An exposure apparatus that illuminates a reticle on which a circuit pattern is formed and projects and exposes the circuit pattern on a wafer.
A reticle stage on which the reticle is mounted;
A wafer stage on which the wafer is mounted;
A linear motor that drives and positions the reticle stage or wafer stage, and a mover in which a main pole permanent magnet and an auxiliary pole permanent magnet that collects a magnetic field around the main pole permanent magnet are disposed, and the main motor The linear motor having a stator coil facing the pole permanent magnet and generating a thrust based on the control current between the main pole permanent magnet and the stator coil,
A main pole permanent magnet having a first permanent magnet thickness, disposed in a plane facing the stator coil;
An auxiliary pole permanent magnet having a second permanent magnet thickness, disposed opposite to the stator coil and arranged in the same plane on which the main pole permanent magnet is arranged,
The exposure apparatus according to claim 1, wherein the first and second permanent magnet thicknesses satisfy the following relationship: first permanent magnet thickness> second permanent magnet thickness. A device manufacturing method comprising:
An exposure step of exposing the substrate with the exposure apparatus according to claim 6;
A device manufacturing method comprising: a developing step of developing the substrate.

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