JP2003177186A - Stage driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out an origin positioning of the main shaft of a non-reaction stage without using an absolute position sensor or a commutation sensor. <P>SOLUTION: A stage and a moving magnet linear motor are individually arranged on a plane guide. A second linear motor group for positioning servo for the linear motor is shaken. An abutting surface and an abutting piece for the origin positioning of an X-axis and a θ-axis are provided. An approximate position in the direction of the main shaft of the stage is derived by calculation based on an operating amount of the second linear motor, and after setting a laser interferometer, a commutation is carried out by a value of the laser interferometer and a movement in the direction to the origin is made. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an initial position driving method for a non-reaction stage which does not generate a reaction force on a support. In recent years, the need for a stage that does not generate a reaction force has been gradually increasing. A typical example is a semiconductor exposure apparatus. In these apparatuses, the movement time of the exposure target is required to be shortened in order to increase the productivity, and the speed of the movable part is increased and the acceleration is increased in order to realize the movement. In these devices, the reaction force generated by the movement of the movable portion has conventionally been transmitted to the floor supporting the device. For this reason, when the rigidity of the floor is insufficient, the reaction force transmitted to the floor shakes itself or an adjacent device, and there is a concern that the setting time and accuracy may be adversely affected. In view of this, it has been proposed to provide a counter-reaction stage that moves in the direction opposite to the stage movable section and provides a counterweight having the same product of the moving speed and the mass as the stage. A motor that uses a linear motor stator for the counterweight has the advantage that a motor for driving the counterweight is not required, but the stator itself moves in the opposite direction to the stage, so its movement is stable. There is a need. Therefore, the guide of the stator uses the flat static pressure guide. The position is synchronously controlled to a position that balances with the stage position, thereby providing a complete reactionless stage. The largest vibration factor in the semiconductor exposure apparatus is the reticle stage. The reticle stage has a lens projection magnification (4
Doubled stroke), speed, acceleration / deceleration. Therefore, a stable guide mechanism at high speed operation is required. Recently, a linear motor is also configured in a direction (X axis) orthogonal to the driving direction (Y axis) to realize non-contact guide in the Y axis. The driving reaction force on the Y-axis side of the reticle stage is transmitted to the linear motor stator. The above-described X-axis linear motor stator is also configured in the linear motor stator. When the reticle stage is driven in the Y axis, a reaction force is generated on the linear motor stator. In an ideal state where the disturbance force such as mounting and the viscous resistance of the guide surface are not considered, the linear motor stator fits in the position that balances with the reticle stage position without doing anything. Due to disturbance factors, the position is shifted from the balanced position. To return it, XYθ is added to the linear motor stator.
An actuator and a sensor are provided so that the three axial directions can be observed and controlled. In order to minimize the above-mentioned disturbance factors, the linear motor stator is also configured on a flat static pressure guide, and the actuator uses a non-contact linear motor. Further, in order to minimize the influence of heat on the reticle stage, a moving magnet type is used for the Y-axis linear motor. In this case, a magnet is configured on the movable reticle stage, and a coil is configured on the stator side. Since the reticle stage has a long stroke, the efficiency of a single coil is low, so that the coil is divided and only the coil under the magnet is excited, so-called coil switching drive (Japanese Patent Application Laid-Open No. H11-341853). In order to perform the coil switching drive, it is necessary to know on which position of the divided coil the magnet is located. In the moving coil system, the approximate position of the mover is known by detecting the magnetic field of the magnet using a Hall element or the like, and hardware commutation is performed. [0004] Means for knowing the precise position of the reticle stage by using a laser interferometer or the like is separately prepared, but they have a relative position detecting function.
Until initialization is performed at the reference position, it cannot be handled as absolute coordinates. Further, if an absolute position sensor such as an ultrasonic sensor is separately provided, not only the structure becomes complicated, but also a function used only at the time of initial position driving, causing an increase in cost. In the moving coil system, if the phase relationship between the coil and the magnet is known, the driving direction can be determined.
Initialization is possible, but in the moving magnet method, since it is necessary to know on which position the magnet is positioned on the divided coil, the approximate position of the mover can be determined by a simple method such as a Hall element. I can't know. For this reason, some kind of absolute position detection has been required, but if a sensor is provided on the mover side, the wiring must be taken into consideration, which may cause a reduction in reliability or disturbance, which may lower the stage performance. there were. An object of the present invention is to provide a stage driving method which does not require the absolute position sensor as described above. [0008] In order to achieve the above object, the present invention provides a stage which moves on a planar guide surface in the XY directions, the X direction being shorter than the Y direction, A first linear motor that generates a force for driving the stage in the X and Y directions and moves on a guide surface parallel to the guide surface; and a first drive motor that generates a force for driving the first linear motor from the guide surface. And a second linear motor for positioning the XYθ axis from the guide surface of the linear motor. The position of the stage is determined based on the amount of operation on the second linear motor when the first linear motor generates a driving force when pressed against the second linear motor. A method for calculating the position of the stage will be described below. The second linear motor has two X motors on the X side and Y motors on the Y side.
It is assumed that the first linear motor is servo-controlled so that the first linear motor remains at a predetermined position by the action of the linear motors. The Y-axis plus side of the X-side linear motor is called MXf, and the Y-axis minus side of the X-side linear motor is called MXb. The force generated by the first linear motor is FXM
The generation force of Xf is Fxf, and the generation force of MXb is Fxb,
Assuming that the position of MXb is the origin of the Y axis and the coordinate at which FX occurs, that is, the Y coordinate of the stage is LY, and the distance between MXf and MXb is L, the sum in the X direction is zero. FX + Fxf + Fxb = 0 Is also zero, FX × LY + Fxf × L = 0 By solving the above simultaneous equations, LY = Fxf ÷ (−Fxb−Fxf) × L. FIG. 1 is a drawing showing the features of the present invention best, and shows a characteristic portion of FIG. 3 which is a specific drawing. In the figure, Stage is a stage that is a movable object, CMYL is a linear motor stator for driving the stage, MagXL is an X-axis mover magnet, CoilXL is an X-axis stator coil, MXLF,
MXLB is a linear motor, RefBar is an abutment surface of the X-axis origin, RefPiece is an abutment piece of the X-axis origin,
It is. First, the linear motors MXLF and MXLB
Are servo-controlled so that the linear motor stator CMYL stays at a predetermined position. A current is applied to CoilXL from a control circuit (not shown) to generate a magnetic field. The force FX is generated by the action of the magnetic field and the magnet MagXL.
Push “stage” to the right of the drawing. The two RefPieces are configured on the Stage, and divide the force FX equally and press the abutment surface RefBar. Butt surface RefBar
Is fixed to a stage base not shown, and as a result, the FX is transmitted to the stage base. On the other hand, the stator coil Co
A reaction force FX is generated in ilXL. This power is 2
To the two linear motors MXLF and MXLB. Since the linear motor acts to keep the linear motor stator CMYL at the same position, the component force Fxf, Fx of the force FX is set so that the resultant force on the linear motor stator CMYL becomes zero.
A reaction force of the same magnitude as b results. The linear motors MXLF and MXLB are fixed to the stage base like the abutment surface RefBar, and the reaction forces cancel each other out on the stage base. In this state, the control circuit (not shown) obtains the forces Fxf and Fxb applied to the linear motors MXLF and MXLB from the motor current and the like. From this, LY = Fxf ÷ (−Fxb−Fxf) × L is calculated to obtain LY. Based on the obtained LY, it is determined on what order the magnet is located above the divided coil, and switching drive is performed so as to excite the coil. As described above, according to the present invention,
While servoing the linear motor stator to a predetermined position,
Determining the position of the stage based on the amount of servo operation when the stage is pressed against the abutment in the X direction eliminates the need for absolute position sensors, commutation sensors, and wiring, and provides a low-cost and highly reliable stage can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing the concept of an embodiment of a stage according to the present invention. FIG. 2 is a view showing the concept of an embodiment of the stage according to the present invention, and shows a state in which the stage position is at the front. FIG. 3 is a top view showing one embodiment of the stage of the present invention. FIG. 4 is a side view showing one embodiment of the stage of the present invention. FIG. 5 is a view showing a conventional stage having an ultrasonic displacement sensor. FIG. 6 is a diagram showing a conventional motor having a commutation sensor. [Description of Signs] AirGuide Static Pressure Bearing Pad Base Stage Surface Plate CMYL Left X-axis Linear Motor Stator Support Case CMYR Right X-Axis Linear Motor Stator Support Case CoilRL Right Y-axis Linear Motor Stator Coil Group CoilYL Left Y-axis Linear Motor Stator coil group ComSensor Commutation sensor ComScale Commutation scale ComCable Commutation sensor cable IFMXX Axis interferometer IFMYL Y axis left interferometer IFMYR Y axis right interferometer Mirror Reflector mirror for interferometer MYL Left stator support Y axis linear motor MXLF Left Rear stator supporting X-axis linear motor MXLB Left front stator supporting X-axis linear motor MagYL Left Y-axis linear motor mover magnet group MagXL Left X-axis Linear motor mover magnet group MYR Right stator support Y-axis linear motor MXRF Right back stator support X-axis linear motor MXRB Right front stator support X-axis linear motor MagYR Right Y-axis linear motor mover magnet group MagXR Right X-axis Linear motor mover magnet group RefBar abutment surface RefPiece abutment piece Stage

Continuation of front page    F term (reference) 2F078 CA02 CB04 CB13 CC02                 5F031 CA07 HA53 KA06 KA08 LA08                       MA27                 5F046 CC03 CC18 DB04 DC14                 5H303 AA06 DD04 DD19 DD30 FF07                       FF08 FF16 FF20 QQ01 QQ07

Claims (1)

1. A stage which moves on a planar guide surface in the XY directions, generates a stage in which the X direction is shorter than the Y direction, and a force for driving the stage in the XY directions from the left and right sides of the stage. A first linear motor that moves on a guide surface parallel to the guide surface, and a force that drives the first linear motor from the guide surface; and positions the XYθ axis from the guide surface with the first linear motor. A second linear motor to be driven and an abutment reference serving as an absolute coordinate origin of the stage in the X direction. Knowing the approximate position of the stage based on the amount of operation on the second linear motor when a driving force is generated on the first linear motor when pressed against the abutment reference Stage drive system which is characterized.