JP2009088018A - Stage control method, stage control apparatus, exposure method, exposure apparatus, and device manufacturing method - Google Patents

Abstract

Control of the surface position and posture of a substrate is maintained with high accuracy.
A stage WTB driven in a first direction by a first drive signal and driven in a second direction intersecting the first direction by a second drive signal is controlled. A correction step of correcting the first drive signal based on the second drive signal is provided.
[Selection] Figure 4

Description

  The present invention relates to a stage control method, a stage control apparatus, an exposure method, an exposure apparatus, and a device manufacturing method.

  In a photolithography process provided as one of manufacturing processes of an image sensor such as a semiconductor element, a liquid crystal display element, a CCD (Charge Coupled Device), a thin film magnetic head, and other various devices, a mask or a reticle (hereinafter, these are collectively referred to) In some cases, an exposure apparatus is used that transfers a pattern formed on a mask) to a substrate such as a glass plate or a wafer coated with a photoresist via a projection optical system.

  In this type of exposure apparatus, by moving the holder that holds the substrate while the substrate stage is supported, the vibration caused by the movement is settled (settling) after the substrate is moved to a preset exposure position. After reaching the state, the mask pattern is transferred by irradiating the mask with exposure light.

When the substrate stage is moved using a driving device such as a linear motor, the position in the substrate surface direction or the posture (tilt) of the substrate may change due to the mechanical characteristics of the substrate stage. When such a change occurs, the positional relationship of the substrate surface with respect to the image plane of the projection optical system changes according to the position in the substrate, and thus the pattern may not be transferred faithfully. Therefore, Patent Document 1 discloses a technique for controlling the surface position and posture of a substrate by driving a holder (that is, a substrate) with six degrees of freedom with respect to the substrate stage.
JP-A-2-35709

However, the following problems exist in the conventional technology as described above.
When the substrate stage is moved using the driving device, a force may be generated in the optical axis direction of the projection optical system due to the leakage thrust of the motor.
In this case, when the force due to the leakage thrust is applied as a disturbance, an error occurs in the surface position and posture of the substrate described above, and the pattern transfer accuracy may decrease.

  The present invention has been made in consideration of the above points, and provides a stage control method, a stage control apparatus, an exposure method, an exposure apparatus, and a device manufacturing method capable of maintaining the control of the substrate surface position and orientation with high accuracy. The purpose is to provide.

In order to achieve the above object, the present invention adopts the following configuration corresponding to FIGS. 1 to 7 showing the embodiment.
The stage control method of the present invention is a stage control for controlling a stage (WST) driven in a first direction by a first drive signal and driven in a second direction intersecting the first direction by a second drive signal. The method includes a correction step of correcting the first drive signal based on the second drive signal.

The stage controller of the present invention controls a stage (WST) driven in the first direction by the first drive signal and driven in the second direction intersecting the first direction by the second drive signal. The stage control device includes a correction unit (72) that corrects the first drive signal based on the second drive signal.
Therefore, in the stage control method and the stage control apparatus of the present invention, when the stage (WST) is driven in the second direction, the force in the first direction applied to the stage is calculated based on the second drive signal. By correcting the first drive signal according to the result, the stage (WST) can be driven in the first direction so as to cancel the disturbance even when a force such as a leakage thrust is applied due to the disturbance. .

The exposure method of the present invention is characterized by using the stage control method described above.
Furthermore, the exposure apparatus of the present invention is characterized by including the stage control device described above.
Therefore, in the exposure method and exposure apparatus of the present invention, the surface of the substrate (W) held on the stage (WST) can be controlled to a predetermined position and posture, and the pattern transfer accuracy is maintained with high accuracy. can do.

And the device manufacturing method of this invention uses the stage control method described previously, It is characterized by the above-mentioned.
Therefore, in the device manufacturing of the present invention, it is possible to manufacture a high-quality device in which the pattern is transferred to the substrate with high accuracy.

  In order to explain the present invention in an easy-to-understand manner, the description has been made in association with the reference numerals of the drawings showing one embodiment, but it goes without saying that the present invention is not limited to the embodiment.

  In the present invention, the control of the surface position and posture of the substrate can be maintained with high accuracy, and the pattern transfer accuracy can be improved.

Embodiments of a stage control method, a stage control apparatus, an exposure method, an exposure apparatus, and a device manufacturing method according to the present invention will be described below with reference to FIGS.
Here, for example, description will be made assuming that the present invention is applied to a batch exposure type projection exposure apparatus such as a stepper. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

(Outline of exposure equipment)
FIG. 1 is a block diagram showing functional units constituting the projection exposure apparatus of this example. In FIG. 1, the chamber for housing the projection exposure apparatus is omitted.
In FIG. 1, a laser light source 1 composed of a KrF excimer laser (wavelength 248 nm) or an ArF excimer laser (wavelength 193 nm) is used as a light source for exposure. As the light source for the exposure, other F2 lasers (wavelength 157 nm) such as those emitting laser light in the ultraviolet region at the oscillation stage, laser light in the near infrared region from a solid-state laser light source (such as YAG or semiconductor laser) It is also possible to use a lamp that emits high-frequency laser light in the vacuum ultraviolet region obtained by converting the wavelength of the above, or a mercury discharge lamp that is often used in this type of exposure apparatus.

  Illumination light (exposure light) IL for exposure as an exposure light source from the laser light source 1 is a uniformizing optical system 2 composed of a lens system and a fly-eye lens system, a beam splitter 3, and variable dimming for light amount adjustment. The reticle blind 7 is irradiated with a uniform illuminance distribution through the device 4, the mirror 5, and the relay lens system 6. Illumination light IL limited to a predetermined shape (for example, a quadrangle for the batch exposure type, for example, a slit shape for the scanning exposure type) by the reticle blind 7 is irradiated onto the reticle R as a mask via the imaging lens system 8 and is thus used. An image of the opening of the reticle blind 7 is formed on R. The illumination optical system 9 includes the homogenizing optical system 2, the beam splitter 3, the variable light dimmer 4 for adjusting the light amount, the mirror 5, the relay lens system 6, the reticle blind 7, and the imaging lens system 8. .

  Of the circuit pattern region (pattern) formed on the reticle R, the image of the portion irradiated with the illumination light is a two-sided telecentric substrate (a sensitive substrate or a photoreceptor) via a projection optical system PL with a projection magnification β of a reduction magnification. ) Is imaged and projected onto a wafer (substrate) W coated with a photoresist. Although the projection optical system PL is a refractive system, a catadioptric system or the like can also be used. In addition to the wafer W, a glass substrate for liquid crystal, a ceramic substrate for magnetic head, and the like can be applied. Hereinafter, the Z-axis is taken in parallel to the optical axis AX of the projection optical system PL, the X-axis is parallel to the plane of FIG. 1 in the plane perpendicular to the Z-axis, and the Y-axis is perpendicular to the plane of FIG. Take and explain. Although the projection exposure apparatus in the present embodiment is a collective type, in the case of the scanning exposure type, the direction along the Y axis (Y direction) is the scanning direction of the reticle R and the wafer W during scanning exposure, and the reticle. The illumination area on R has an elongated shape in a direction (X direction) along the X axis that is a non-scanning direction.

  The reticle R arranged on the object plane side of the projection optical system PL is held on the reticle stage RST (mask stage) by vacuum suction or the like. The movement coordinate position (X-direction, Y-direction position, and rotation angle around the Z-axis) of reticle stage RST is fixed to reticle moving mirror Mr fixed to reticle stage RST and the upper side surface of projection optical system PL. Measurement is performed sequentially with the reference mirror (not shown) and the reticle laser interferometer system 10 arranged to face the reference mirror. The reticle laser interferometer system 10 actually constitutes a triaxial laser interferometer having at least one axis in the X direction and two axes in the Y direction.

  In addition, movement of reticle stage RST is performed by reticle drive system 11 including a linear motor, a fine actuator, and the like. Measurement information of the reticle laser interferometer system 10 is supplied to a stage control unit 14, which in turn controls the measurement information and control information (input information) from a main control system 20 comprising a computer that controls the overall operation of the apparatus. ) To control the operation of the reticle drive system 11.

  On the other hand, wafer W arranged on the image plane side of projection optical system PL is held on wafer stage (stage) WST by vacuum suction or the like. Wafer stage WST includes a wafer table WTB (details will be described later) for attracting and holding wafer W, and a Z drive device for controlling the focus position (position in the Z direction) of wafer W and the inclination angles around the X and Y axes. 30a to 30c (details will be described later). (In FIG. 1, wafer stage WST is simply illustrated).

  In the case of the collective exposure type, wafer stage WST moves stepwise on guide surface Ja of surface plate J in the X and Y directions. In the case of the scanning exposure type, wafer stage WST is placed on guide surface Ja so that it can move at a constant speed in at least the Y direction and can move stepwise in the X and Y directions during scanning exposure. The movement coordinate position of wafer stage WST (the position in the X direction, the Y direction, and the rotation angle around the Z axis) includes a reference mirror Mf fixed to the lower part of projection optical system PL, and reflection surface Mw of wafer stage WST. The laser interferometer system 12 arranged so as to face this is sequentially measured. The reflecting surface Mw, the reference mirror Mf, and the laser interferometer system 12 actually constitute a three-axis laser interferometer having at least two axes in the X direction and one axis in the Y direction. The laser interferometer system 12 also actually includes a biaxial laser interferometer for measuring rotation angles (yawing and pitching) around the X axis and the Y axis.

  Also, oblique incidence type multi-point autofocus sensors 23A and 23B are fixed to the lower side surface of the projection optical system PL. The stage control unit 14 calculates defocus amounts from the image plane of the projection optical system PL at the plurality of measurement points using information on the lateral shift amounts of the slit images, and these defocus amounts are controlled in a predetermined manner during exposure. The Z driving devices 30a to 30c in wafer stage WST are driven by an autofocus method so as to be within accuracy.

  The stage control unit 14 also includes a reticle-side control circuit that optimally controls the reticle drive system 11 based on measurement information from the reticle laser interferometer system 10, and a wafer based on measurement information from the laser interferometer system 12. And a wafer-side control circuit that optimally controls the drive system 13 (details will be described later). Further, the main control system 20 exchanges commands and parameters with each control circuit in the stage control unit 14 and executes optimum exposure processing according to a program designated by the operator. For this purpose, an operation panel unit (not shown) (including an input device and a display device) that provides an interface between the operator and the main control system 20 is provided.

  Furthermore, it is necessary to align the reticle R and the wafer W in advance for exposure. Therefore, the projection exposure apparatus of FIG. 1 includes a reticle alignment system (RA system) 21 for setting the reticle R at a predetermined position and an off-axis alignment system 22 for detecting marks on the wafer W. Is provided.

  In FIG. 1, in the case of the batch exposure type, an operation of projecting the pattern of the reticle R onto one shot area on the wafer W via the projection optical system PL under the illumination light IL, and the wafer stage WST. The operation of stepping and moving the wafer W in the X and Y directions is repeated by the step-and-repeat method, and the pattern image of the reticle R is transferred to all shot areas on the wafer W.

  FIG. 2 is a plan view showing a schematic configuration of wafer stage WST, and FIG. 3 is a front view of wafer stage WST. As shown in FIGS. 2 and 3, wafer stage WST is a moving stage 41 as a Y coarse movement stage, and a fine movement stage that holds wafer W and is supported by movement stage 41 via Z driving devices 30 a to 30 c. Wafer table WTB. The moving stage 41 is placed on the guide surface Ja so as to be movable in the X direction and the Y direction via an air bearing 42 provided on the bottom surface.

  As shown in FIG. 2, the Z driving devices 30 a to 30 c are arranged at three positions at the apexes of the triangle between the moving stage 41 and the wafer table WTB. Each of the Z driving devices 30 a to 30 c is provided on the moving stage 41. It is constituted by a voice coil motor including a stator 43a and a movable element 43b provided on the wafer table WTB and driven in the Z direction with respect to the stator 43a. Each mover 43b is driven independently under the control of the stage control unit 14. Therefore, by driving the mover 43b in the Z drive devices 30a to 30c by the same amount, the wafer table WTB (that is, the wafer W) can be moved in the Z direction, and the mover 43b in the Z drive devices 30a to 30c can be moved. By varying the drive amount, wafer table WTB (that is, wafer W) can be moved in the θX direction (rotation direction around the X axis) and θY direction (rotation direction around the Y axis).

  Height sensors 31a to 31c that can measure the displacement amount of the Z driving devices 30a to 30c in the focus direction (Z direction) with a resolution of, for example, about 0.01 μm are attached in the vicinity of the Z driving devices 30a to 30c, respectively. It has been. The measurement results of the height sensors 31 a to 31 c are output to the stage control unit 14.

  The wafer stage WST includes an X driving device 44X that drives the wafer table WTB in the X direction relative to the moving stage 41, and Y driving devices 44Y and 44Y that drive the wafer table WTB in the Y direction relative to the moving stage 41. (Y driving device 44Y is not shown in FIG. 3). The X driving device 44X is a voice coil comprising a stator 45a provided on the moving stage 41 and a mover 45b that protrudes from the side surface on the + X side of the wafer table WTB and is driven in the X direction with respect to the stator 45a. Consists of a motor. Similarly, each Y drive unit 44Y protrudes from the stator 46a provided on the moving stage 41 and the side surface on the −Y side of the wafer table WTB (see FIG. 2), and in the Y direction with respect to the stator 46a. It is comprised by the voice coil motor which consists of the needle | mover 46b to drive, and is arrange | positioned at intervals in the X direction.

  Accordingly, by driving the mover 45b in the X drive unit 44X, the wafer table WTB (that is, the wafer W) can be moved in the X direction, and the mover 46b in the Y drive units 44Y and 44Y is driven by the same amount. Thus, wafer table WTB (that is, wafer W) can be moved in the Y direction. Furthermore, the wafer table WTB (that is, the wafer W) can be moved in the θZ direction (the rotation direction around the Z axis) by changing the drive amount or drive direction of the mover 46b in the Y drive devices 44Y and 44Y.

  That is, by controlling the driving of the Z driving devices 30a to 30c, the X driving device 44X, and the Y driving device 44Y, the wafer table WTB (that is, the wafer W) is moved in the Z direction, the X direction, and the Y direction with respect to the moving stage 41. , ΘX direction, θY direction, and θZ direction can be finely driven with six degrees of freedom.

  Wafer stage WST is provided so as to be movable in the Y-axis direction along Y-axis guide 47 that penetrates between wafer table WTB and moving stage 41 in the Y-axis direction. Wafer stage WST is composed of a stator provided on Y-axis guide 47 and a mover provided on wafer stage WST, for example, by a moving magnet type Y-axis linear motor 48 in the Y-axis direction. Move with a long stroke. Wafer stage WST is made up of, for example, a moving coil type X-axis linear motor 50 including a stator 49a extending in the X-axis direction and movers 49b provided at both ends of Y-axis guide 47. Then, it moves with a long stroke in the X-axis direction via the Y-axis guide 47. At this time, by making the movement amount and the movement direction of the movers 49b and 49b the same, the wafer table WTB (that is, the wafer W) can be moved in the X-axis direction, and the movement amount or movement of the movers 49b and 49b. By making the directions different, wafer table WTB (ie, wafer W) can be moved in the θZ direction.

The driving of the Y-axis linear motor 48 and the X-axis linear motor 50 is also controlled by the stage control unit 14.
The Z drive devices 30a to 30c, the X drive device 44X, the Y drive device 44Y, the Y axis linear motor 48, and the X axis linear motor 50 constitute a drive system 13.

  The mirror-processed side surface MwX of wafer table WTB is irradiated with two laser beams separated in the Y direction from laser interferometer 12X, and the mirror-processed side surface MwY of wafer table WTB in the + Y direction is irradiated. Is irradiated with a laser beam from the laser interferometer 12Y, and the X-direction and Y-direction coordinates of the wafer table WTB and the rotation angle around the Z-axis are measured by the laser interferometers 12X and 12Y. Laser interferometers 12X and 12Y correspond to the laser interferometer system 12 of FIG.

  Based on the measurement information of the laser interferometers 12X and 12Y, the stage control unit 14 shown in FIG. 1 has a coarse movement mechanism (Y-axis linear motor 48, X-axis linear motor 50) and fine movement mechanism (Z drive devices 30a to 30c, The drive system 13 including the X drive device 44X and the Y drive device 44Y) is driven. The former coarse movement mechanism can be used for the step movement of the wafer table WTB in the batch exposure type and the scanning exposure type, and can further be used for the constant speed movement of the wafer table WTB during the synchronous scanning in the scanning exposure type. The latter fine movement mechanism can be used to correct the positioning error of the wafer table WTB in the batch exposure type and the scanning exposure type, and is further used to correct the synchronization error of the wafer table WTB in the scanning exposure type. You can also

  FIG. 4 is a block diagram of a control system related to driving in the Z direction according to wafer stage WST. As shown in FIG. 4, the control system for controlling the position and orientation of wafer table WTB in the Z direction includes a feedback control unit 70, a feedforward control unit 71, an XY drive correction unit (correction unit) 72, and a target position generator 73. These are roughly divided into operation units 80 to 82. The feedback control unit 70 includes a low-pass filter, a calculation unit, a PI (Proportional Integral) controller, and the like. In the present embodiment, description will be made assuming that feedback control and feedforward control are performed using detection results of the autofocus sensors 23A and 23B and the height sensor 31 (31a to 31c), but only one of the detection results is detected. You may perform feedback control using.

  Target position generator 73 outputs a reference signal that gives a target value of the position and orientation of wafer stage WST (wafer table WTB) in the Z direction (first direction). This target position generator 73 is provided in the main control system 20. The calculation unit 80 returns the reference signal output from the target position generator 73 and the feedback from the sensors (hereinafter, the autofocus sensors 23A and 23B and the height sensor 31 (31a to 31c) are referred to as “sensor 32”). An error signal corresponding to the difference from the signal is calculated.

  The feedback control unit 70 generates a control signal (first drive signal) for driving the Z drive devices 30a to 30c based on the control signal output from the calculation unit 80, and for example, the surface shape of the wafer W In order to prevent excessive control from being performed due to an abrupt change, a filtering process for cutting a high-frequency component of a signal output from the calculation unit 80 is performed.

The calculation unit 81 calculates a control signal obtained by adding the control signal output from the feedforward control unit 71 to the control signal output from the feedback control unit 70.
The feedforward control unit 71 completes the exposure of the wafer stage WST during exposure caused by the step movement in the X direction of the wafer stage WST performed when the exposure process for the next shot area is performed after the exposure process for one shot area is completed. A correction amount for correcting the position in the Z direction is generated. This is because there is a possibility that the position of the wafer W in the Z direction fluctuates due to vibration caused by the step movement and an autofocus error occurs.
This correction amount is set according to the step length, and details thereof are described in Japanese Patent Application No. 2004-200317.

  The calculation unit 82 calculates a control signal obtained by adding the control signal output from the XY drive correction unit 72 to the control signal (first drive signal) output from the calculation unit 81. The XY drive correction unit 72 is generated when the wafer table WTB is driven in the X direction and the Y direction with respect to the moving stage 41 by the X drive device 44X and the Y drive device 44Y (referred to collectively as the drive device 44 as appropriate). A control signal (second drive signal) for correcting the thrust in the direction (so-called leakage thrust) is output.

  This leakage thrust is generated by a relationship expressed by a linear function with respect to an acceleration profile (time change of acceleration) when the driving device 44 drives the wafer table WTB.

FIG. 5 shows a thrust profile (that is, an acceleration profile) when the wafer table WTB is driven in the X-axis direction by the X driving device 44X.
FIG. 6 is a thrust profile (that is, an acceleration profile) in the Z direction applied to wafer table WTB when wafer table WTB is driven in the X-axis direction by X driving device 44X.

As shown in FIGS. 5 and 6, the profile during driving in the X-axis direction and the profile in the Z-axis direction have a first-order correlation.
Further, the profile shown in FIG. 6 differs depending on the position of wafer table WTB in the Z direction.
Therefore, the acceleration profile Fz in the Z direction of the wafer table WTB accompanying the driving of the X driving device 44X is expressed by the following equation using the acceleration profile Fx in the X axis direction and the position Tz in the Z direction of the wafer table WTB. The
Fz = a × Fx × Tz + b (1)
a and b are constants

The above constants a and b are obtained by measuring the thrust (acceleration) in the Z-axis direction when the wafer table WTB is driven in the X-axis direction by the X driving device 44X in advance by changing the Z position of the wafer table WTB. Set and memorize.
Then, the XY drive correction unit 72 controls to cancel this acceleration (thrust) according to the Z position of the wafer table WTB measured by the sensor 32 and the acceleration profile Fz obtained based on the equation (1). The signal is output to the calculation unit 82.

The control signal calculated by the calculation unit 82 is output to wafer stage WST (wafer table WTB, Z driving devices 30a to 30c), and the Z position and posture of wafer table WTB are controlled.
In the above description, the thrust in the Z direction generated in the wafer table WTB as the X drive device 44X is driven has been described, but actually, the XY drive correction unit 72 is accompanied by the drive of the Y drive device 44Y. Similarly, the thrust in the Z direction generated in the wafer table WTB is obtained in the same manner, and a control signal for canceling this thrust is output.

The configuration of the control system for correcting the position of the wafer stage 37 in the Z direction has been described above. Next, the operation during exposure will be briefly described.
First, when starting the exposure process, the main control system 20 controls the drive system 13 to move the wafer stage WST stepwise in the XY plane, so that the shot area to be exposed is directly below the projection optical system PL (projection area). And the surface of the wafer W is made to coincide with the image plane of the projection optical system PL. Actually, in this embodiment, the step movement of the wafer stage WST is mainly performed in the X-axis direction by driving the X-axis linear motor 50, and the wafer table WTB in the X-axis direction is positioned with high precision (fine). Alignment) is performed by driving the X driving device 44X.

  During step movement of wafer stage WST, target position generator 73 outputs a reference signal that gives a target value for the position and orientation of wafer W in the Z direction. The reference signal output from the target position generator 73 is input to the calculation unit 80, and an error signal corresponding to the difference from the feedback signal from the sensor is calculated in the calculation unit 80 and output to the feedback control unit 70.

  When a control signal is input to the feedback control unit 70, a control signal for driving the Z driving devices 30a to 30c is generated based on the control signal, and is output to the calculation unit 81 after low-pass filtering processing is performed. .

  At this time, the feedforward control unit 71 generates a correction amount for correcting the position in the Z direction of wafer stage WST (wafer table WTB) accompanying step movement (for example, step movement in the X direction), and inputs the correction amount to calculation unit 81. Let And in the calculating part 81, the control signal (correction amount) which the feedforward control part 71 outputs is added (correction | amendment) to the control signal for driving Z drive device 30a-30c output from the feedback control part 70. And output to the calculation unit 82.

  The control signal output from the XY drive correction unit 72 is added to the control signal input to the calculation unit 82. The control signal output from the XY drive correction unit 72 is expressed by the above equation (1) according to the position in the Z direction of the wafer W measured by the sensor 32 and the acceleration profile during driving of the X drive unit 44X. As a signal for correcting the obtained acceleration profile in the Z direction, the signal is output to the calculation unit 82 by feedforward.

  In the control signal calculated and corrected by the calculation unit 82, disturbance factors such as thrust in the Z direction applied when the X driving device 44X is driven as the wafer stage WST is moved stepwise are corrected in advance by feedforward. Even after the disturbance D (see FIG. 4) is actually applied, the Z driving devices 30a to 30c are driven by the driving signal that eliminates (cancels) the adverse effects caused by these disturbance factors, and the wafer table WTB (ie, wafer W) The position and orientation in the Z direction are controlled.

  The above control is performed every time the step movement to the shot area on the wafer W is performed, and also when the step movement moves not only in the X direction but also in the Y direction or both the X direction and the Y direction. Thus, it is possible to prevent the vibration caused by the step movement from adversely affecting the autofocus.

  As described above, in the present embodiment, the Z drive device 30a is a drive signal obtained by correcting a disturbance factor such as a leakage thrust generated when the wafer stage WST is moved stepwise by feedforward based on the acceleration information of the wafer stage WST. Since ~ 30c (wafer table WTB) is driven, positioning of the wafer W can be performed in a state where errors due to disturbance are eliminated, and control of the surface position and orientation of the wafer W can be maintained with high accuracy. . Therefore, in the present embodiment, the pattern transfer accuracy to the wafer W can be maintained with high accuracy.

In the present embodiment, since the Z driving devices 30a to 30c are driven using the correction amount corresponding to the position in the Z direction of wafer table WTB, an error that differs for each Z position of wafer table WTB is accurately corrected. Can do.
In particular, in the present embodiment, since the correction amount is expressed by a linear function with respect to the Z position of the wafer table WTB, the correction amount can be easily set and the correction amount can be set with high accuracy. Is possible.

Next, a second embodiment of the stage control method will be described with reference to FIG.
In the second embodiment, a disturbance compensator using a disturbance observer is added to the control block diagram shown in FIG. 4 to cancel disturbance factors such as fluctuations in the friction characteristics of the linear bearing guide.
In this figure, the same components as those of the first embodiment shown in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted.

In the disturbance compensator 90 shown in FIG. 7, first, a control signal for driving the Z driving devices 30a to 30c output from the feedback control unit 70 and added with the control signal output from the feedforward control unit 71, Filtering is performed using a transfer function Q (s) by a filter 91 formed of a second-order low-pass filter.
On the other hand, the measurement result of the sensor 32 to which the measurement error n is added is input to the filter 92. The filter 92 includes an inverse model (transfer function Pn (s)) of a transfer function P (s) and a second-order low-pass filter (Q (s)) for the wafer stage WST (wafer table WTB) to be controlled. The actual thrust value command value applied to the controlled object is estimated from the measurement result of the sensor 32 to which the measurement error n is added.

  And the calculating part 93 estimates the disturbance force currently applied to the wafer table WTB which is a control object as a disturbance estimation part by taking the difference of the filters 91 and 92 (disturbance estimation step), and generates a disturbance compensation signal Output to the arithmetic unit 94 as a unit. The calculation unit 94 adds the estimated disturbance force to the control signal output from the calculation unit 81 to generate a disturbance compensation signal that compensates for the control signal for driving the Z driving devices 30a to 30c (disturbance compensation signal generation). Step).

As described above, in this embodiment, in addition to obtaining the same operation and effect as those in the first embodiment, a disturbance observer (air) associated with driving of the wafer stage WST is added by adding a disturbance observer to the control block. It is possible to estimate and compensate the guide friction of the bearing 42, and to suppress disturbance factors particularly in the low frequency range. In this disturbance observer, since the input to the filter 91 is a signal before correction by the XY drive correction unit 72, the correction by the XY drive correction unit 72 is not compensated as a disturbance, and is surely caused by a true disturbance factor. Adverse effects can be suppressed.
Therefore, in this embodiment, it is possible to maintain the control of the surface position and posture of the wafer W held on the wafer table WTB with higher accuracy.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above-described embodiment, the Z-axis direction thrust generated when the wafer table WTB is moved in the X-axis direction is corrected based on the acceleration information in the X-axis direction. Correction method based on acceleration information when moving in the axial direction (third direction) by the third drive signal, and when moving in both the X-axis direction and the Y-axis direction, the X-axis direction and the Y-axis direction It is good also as a system which correct | amends based on both acceleration information of these. Furthermore, in the above embodiment, the thrust applied in the Z-axis direction has been described as being corrected. However, the present invention is not limited to this. For example, based on acceleration information when moving the wafer table WTB in the X-axis direction, A configuration in which thrust generated in the Y-axis direction is corrected, or a configuration in which thrust generated in the Y-axis direction and thrust generated in the X-axis direction are corrected based on acceleration information when moving in the Z-axis direction may be employed. That is, the present invention is based on a drive signal (acceleration information thereof) when moving to at least one of the first axis and the second axis of a stage movable in three axis directions. It is possible to correct the thrust generated along the three axes.

  The substrate (object) in each of the above embodiments is not limited to a semiconductor wafer for manufacturing a semiconductor device, but a glass substrate for a display device, a ceramic wafer for a thin film magnetic head, or a mask or reticle used in an exposure apparatus. The original plate (synthetic quartz, silicon wafer) or the like is applied.

  As the exposure apparatus, in addition to a step-and-repeat type projection exposure apparatus (stepper) that collectively exposes the pattern of the reticle R while the reticle R and the wafer W are stationary, and sequentially moves the wafer W stepwise, the reticle The present invention can also be applied to a step-and-scan type scanning exposure apparatus (scanning stepper) that scans and exposes the pattern of the reticle R by synchronously moving R and the wafer W. The present invention can also be applied to a step-and-stitch type exposure apparatus that partially transfers at least two patterns on the wafer W.

  The type of exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor element that exposes a semiconductor element pattern on the wafer W, but is an exposure apparatus for manufacturing a liquid crystal display element or a display, a thin film magnetic head, an image sensor (CCD). Alternatively, it can be widely applied to an exposure apparatus for manufacturing a reticle or a mask.

The light source of the exposure apparatus to which the present invention is applied includes not only KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ laser (157 nm), but also g-line (436 nm) and i-line (365 nm). ) Can be used. Further, the magnification of the projection optical system may be not only a reduction system but also an equal magnification or an enlargement system. In the above embodiment, the catadioptric projection optical system is exemplified, but the present invention is not limited to this, and the optical axis (reticle center) of the projection optical system and the center of the projection area are set at different positions. It can also be applied to a refraction type projection optical system.

  Further, the present invention is applied to a so-called immersion exposure apparatus in which a liquid is locally filled between the projection optical system and the substrate, and the substrate is exposed through the liquid. It is disclosed in the publication No. 99/49504 pamphlet. Further, in the present invention, the entire surface of the substrate to be exposed as disclosed in JP-A-6-124873, JP-A-10-303114, US Pat. No. 5,825,043 and the like is in the liquid. The present invention is also applicable to an immersion exposure apparatus that performs exposure while being immersed.

  The present invention can also be applied to a twin stage type exposure apparatus provided with a plurality of substrate stages (wafer stages). The structure and exposure operation of a twin stage type exposure apparatus are described in, for example, Japanese Patent Laid-Open Nos. 10-163099 and 10-214783 (corresponding US Pat. Nos. 6,341,007, 6,400,441, 6,549). , 269 and 6,590,634), JP 2000-505958 (corresponding US Pat. No. 5,969,441) or US Pat. No. 6,208,407. Furthermore, the present invention may be applied to the wafer stage disclosed in Japanese Patent Application No. 2004-168482 filed earlier by the present applicant.

  An exposure apparatus to which the present invention is applied assembles various subsystems including the constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

Next, an embodiment of a manufacturing method of a micro device using the exposure apparatus and the exposure method according to the embodiment of the present invention in the lithography process will be described. FIG. 8 is a flowchart showing a manufacturing example of a microdevice (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, or the like).
First, in step S10 (design step), function / performance design (for example, circuit design of a semiconductor device) of a micro device is performed, and pattern design for realizing the function is performed. Subsequently, in step S11 (mask manufacturing step), a mask (reticle) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S12 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.
Next, in step S13 (wafer processing step), using the mask and wafer prepared in steps S10 to S12, an actual circuit or the like is formed on the wafer by lithography or the like, as will be described later. Next, in step S14 (device assembly step), device assembly is performed using the wafer processed in step S13. This step S14 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary. Finally, in step S15 (inspection step), inspections such as an operation confirmation test and a durability test of the microdevice manufactured in step S14 are performed. After these steps, the microdevice is completed and shipped.

FIG. 9 is a diagram illustrating an example of a detailed process of step S13 in the case of a semiconductor device.
In step S21 (oxidation step), the surface of the wafer is oxidized. In step S22 (CVD step), an insulating film is formed on the wafer surface. In step S23 (electrode formation step), an electrode is formed on the wafer by vapor deposition. In step S24 (ion implantation step), ions are implanted into the wafer. Each of the above steps S21 to S24 constitutes a pre-processing process at each stage of the wafer processing, and is selected and executed according to a necessary process at each stage.
At each stage of the wafer process, when the above pre-process is completed, the post-process is executed as follows. In this post-processing process, first, in step S25 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step S26 (exposure step), the circuit pattern of the mask is transferred to the wafer by the lithography system (exposure apparatus) and the exposure method described above. Next, in step S27 (development step), the exposed wafer is developed, and in step S28 (etching step), exposed members other than the portion where the resist remains are removed by etching. In step S29 (resist removal step), the resist that has become unnecessary after the etching is removed. By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the wafer.

  Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., from mother reticles to glass substrates and The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a silicon wafer or the like. Here, in an exposure apparatus using DUV (deep ultraviolet), VUV (vacuum ultraviolet) light, or the like, a transmission type reticle is generally used. As a reticle substrate, quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride or quartz is used. In proximity-type X-ray exposure apparatuses, electron beam exposure apparatuses, and the like, a transmissive mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate. Such an exposure apparatus is disclosed in WO99 / 34255, WO99 / 50712, WO99 / 66370, JP-A-11-194479, JP-A2000-12453, JP-A-2000-29202, and the like. .

It is a figure which shows schematic structure of the projection exposure apparatus of embodiment. It is a top view which shows schematic structure of wafer stage WST. It is a front view of wafer stage WST. It is a block diagram of the control system regarding the drive to the Z direction of 1st Embodiment. It is a thrust profile at the time of driving a wafer table to an X-axis direction. This is a thrust profile in the Z direction applied to the wafer table when the wafer table is driven in the X-axis direction. It is a block diagram of the control system regarding the drive to the Z direction of 2nd Embodiment. It is a flowchart which shows an example of the manufacturing process of the microdevice of this invention. It is a figure which shows an example of the detailed process of step S13 in FIG.

Explanation of symbols

  Ja ... Guide surface, R ... Reticle (mask), W ... Wafer (substrate), WST ... Wafer stage (stage), 72 ... XY drive correction unit (correction unit), 93 ... Calculation unit (disturbance estimation unit), 94 ... Calculation unit (disturbance compensation signal generator)

Claims (19)

A stage control method for controlling a stage driven in a first direction by a first drive signal and driven in a second direction intersecting the first direction by a second drive signal,
A stage control method comprising a correction step of correcting the first drive signal based on the second drive signal. The stage control method according to claim 1,
A stage control method for correcting the first drive signal using a correction amount corresponding to the position of the stage in the first direction. The stage control method according to claim 2, wherein
A stage control method in which the correction amount and the position of the stage in the first direction can be expressed by a linear function. In the stage control method according to any one of claims 1 to 3,
A stage control method for correcting the first drive signal by using acceleration information of the stage included in the second drive signal. In the stage control method according to any one of claims 1 to 4,
A stage control method including a step of feeding forward information based on the second drive signal to the first drive signal to drive the stage in the first direction. In the stage control method according to any one of claims 1 to 5,
A disturbance estimation step of estimating a disturbance applied to the stage based on information obtained by driving the stage in the first direction;
A disturbance compensation signal generating step for generating a disturbance compensation signal in which the first drive signal is compensated based on the estimated disturbance obtained in the disturbance estimating step;
And a stage control method in which the stage is driven based on the disturbance compensation signal and the second drive signal. In the stage control method according to any one of claims 1 to 6,
The stage moves along a guide surface including the second direction;
The stage control method, wherein the first direction is a direction substantially orthogonal to the guide surface. The stage control method according to claim 7, wherein
The stage is driven by a third drive signal in a third direction intersecting the second direction within the guide surface,
A stage control method comprising a step of correcting the first drive signal based on the third drive signal.   An exposure method using the stage control method according to claim 1.   A device manufacturing method using the stage control method according to claim 1. A stage control device that controls a stage driven in a first direction by a first drive signal and driven in a second direction that intersects the first direction by a second drive signal,
A stage control apparatus comprising: a correction unit that corrects the first drive signal based on the second drive signal. The stage control device according to claim 11, wherein
The correction unit is a stage control device that corrects the first drive signal using a correction amount corresponding to the position of the stage in the first direction. The stage control apparatus according to claim 12, wherein
The stage control apparatus in which the correction amount and the position of the stage in the first direction can be expressed by a linear function. In the stage control device according to any one of claims 11 to 13,
The correction unit is a stage control device that corrects the first drive signal using acceleration information of the stage included in the second drive signal. In the stage control device according to any one of claims 11 to 14,
A stage controller that feeds information based on the second drive signal to the first drive signal to drive the stage in the first direction. In the stage control device according to any one of claims 11 to 15,
A disturbance estimation unit that estimates a disturbance applied to the stage based on information obtained by driving the stage in the first direction;
A disturbance compensation signal generation unit that generates a disturbance compensation signal that compensates for the first drive signal based on the estimated disturbance obtained by the disturbance estimation unit;
A stage control device for driving the stage based on the disturbance compensation signal and the second drive signal. In the stage control device according to any one of claims 11 to 16,
The stage moves along a guide surface including the second direction;
The stage control device, wherein the first direction is a direction substantially orthogonal to the guide surface. The stage control apparatus according to claim 17, wherein
The stage is driven by a third drive signal in a third direction intersecting the second direction within the guide surface,
The correction unit is a stage control device that corrects the first drive signal based on the third drive signal.   An exposure apparatus comprising the stage control device according to any one of claims 11 to 18.

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