JP2005026504A - Stage apparatus, exposure apparatus and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stage apparatus capable of enhancing the control performance of a stage. <P>SOLUTION: The stage apparatus is provided with a stage capable of holding and moving an object and a drive mechanism for driving the stage on a vibration isolating stand for isolating vibration, and includes a control means for controlling acceleration / deceleration of the drive mechanism by avoiding the coincidence between a period of the natural vibration of the vibration isolating stand and an acceleration time or a deceleration time of the drive mechanism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stage apparatus and an exposure apparatus, and more particularly, to an exposure apparatus used in a lithography process for manufacturing devices such as a liquid crystal display panel, an integrated circuit, and a thin film magnetic head, and a stage apparatus suitable for the exposure apparatus. The present invention relates to an exposure apparatus and a control method.
[0002]
[Prior art]
Conventionally, in a lithography process for manufacturing a liquid crystal display panel, an integrated circuit, and the like, various exposure apparatuses that transfer a mask pattern onto a substrate have been used. For example, as an exposure apparatus for liquid crystal, a step-and-repeat type static exposure type projection exposure apparatus (so-called liquid crystal stepper), a mask stage and a plate stage are scanned in the same direction with respect to the projection optical system. A projection exposure apparatus such as a batch transfer type scanning exposure apparatus that transfers a mask pattern onto a plate (glass substrate) is mainly used. Recently, in response to the increase in the size of liquid crystal display panels and the accompanying increase in the size of plates, exposure of a plurality of shots is performed on a single plate in the same way as a stepper. A step-and-scan scanning exposure apparatus (scanning stepper) capable of exposure has also been developed (for example, Patent Document 1).
[0003]
[Patent Document 1]
JP 2000-0773313 A
[0004]
[Problems to be solved by the invention]
By the way, when an air damper is used for the vibration isolation table on which the exposure apparatus described in Patent Document 1 is mounted, the frequency of the natural vibration of the vibration isolation table (frequency at which the vibration transmissibility becomes a maximum value) is several Hz. There are many. Further, in a stage control apparatus that controls a stage provided in the exposure apparatus, usually, the acceleration / deceleration of steps or scans is often constant. If the acceleration / deceleration of the step is constant, the acceleration / deceleration period may coincide with the synchronization of the natural vibration of the vibration isolation table depending on the step distance and the maximum speed, the entire surface plate shakes greatly, and the positioning and setting performance of the plate stage and mask stage deteriorates There is a problem of doing. In addition, when the scanning acceleration / deceleration is constant, depending on the scanning speed, the scanning acceleration period may coincide with the natural vibration period of the vibration isolation table, the entire surface plate shakes greatly, and the mask stage is performed using the position of the plate stage as a position command. There is also a problem that the following performance of the camera deteriorates. Further, such a problem is that a XY stage having a two-stage structure in which the Y stage is mounted on the upper part of the X stage via the drive mechanism of the Y stage, or a fine movement stage is mounted on the upper side of the coarse movement stage via the drive mechanism. The same can occur in the control system of a so-called coarse / fine movement reticle stage.
[0005]
The present invention has been made in view of such circumstances, and a first object thereof is to provide a stage apparatus and a stage apparatus control method capable of improving the control performance of the stage.
A second object of the present invention is to provide an exposure apparatus capable of improving throughput and pattern transfer accuracy.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a vibration isolation stage (17a) that removes vibration between a stage (mask stage MST, plate stage PST, etc.) that can move while holding an object and a drive mechanism that drives the stage. 17b) is a stage device provided above, and avoids the coincidence between the natural vibration period of the vibration isolation table and the acceleration time or deceleration time of the drive mechanism (acceleration / deceleration of the drive mechanism (average acceleration including negative values)) The control means (for example, the target value output unit 26) for controlling is provided.
According to the present invention, the acceleration or deceleration time of the stage drive mechanism that may be a vibration source that resonates with the natural frequency of the vibration isolation table is driven so that it does not coincide with the period of the natural frequency of the vibration isolation table. By controlling the acceleration / deceleration of the mechanism, the control performance of the stage can be improved by avoiding the influence of the natural vibration of the vibration isolation table.
[0007]
Further, according to the present invention, the control means associates in advance an instruction value (scanning speed, step moving distance, etc.) relating to stage driving and a driving target value (average acceleration / deceleration, maximum speed, etc.) that avoids the natural vibration period. A data table (target value table shown in FIGS. 5 and 6) is provided, and a drive target value associated with an instruction value given from the host is obtained by referring to the data table, and control of the drive mechanism is performed based on the drive target value. It is characterized by performing.
According to the present invention, acceleration time or deceleration time of a stage drive mechanism that may become a vibration source that resonates with the natural frequency of the vibration isolation table by determining the drive target value with reference to the data table. Because the acceleration / deceleration of the drive mechanism can be controlled so that does not coincide with the natural frequency period of the vibration isolation table, the influence of the natural vibration of the vibration isolation table can be avoided and the stage control performance can be improved. .
[0008]
Further, the present invention is characterized in that the acceleration time or the deceleration time is a time that excludes a frequency cycle in which the vibration transmissibility of the vibration isolation table exceeds a half value of the maximum value.
According to the present invention, not only the maximum value of the vibration transmissibility, but also the frequency period and the acceleration / deceleration time that are greatly influenced by resonance do not coincide with each other, so that the control performance of the stage can be further improved.
[0009]
The present invention also provides an exposure apparatus (10) for transferring a predetermined pattern onto a substrate, comprising the stage apparatus (for example, plate stage PST) according to any one of claims 1 to 3, wherein the substrate is mounted on the stage. Is placed.
According to the present invention, since the stage apparatus capable of improving the control performance of the stage is provided, it is possible to improve throughput and pattern transfer accuracy.
[0010]
Further, the present invention is an exposure apparatus that synchronously moves a mask and a substrate to transfer a mask pattern onto the substrate, wherein a master stage (plate stage PST) on which the substrate is placed, and the mask are placed, And a slave stage (mask stage MST) following the master stage, wherein the master stage is the stage apparatus according to any one of claims 1 to 3.
According to the present invention, throughput and pattern transfer accuracy can be improved.
[0011]
The present invention also relates to a method for controlling a stage apparatus including a movable stage holding an object and a drive mechanism for driving the stage on a vibration isolation table for removing vibrations. It has a control process for controlling the acceleration / deceleration of the drive mechanism while avoiding the coincidence between the natural vibration period and the acceleration time or deceleration time of the drive mechanism.
According to the present invention, the acceleration or deceleration time of the stage drive mechanism that may be a vibration source that resonates with the natural frequency of the vibration isolation table is driven so that it does not coincide with the period of the natural frequency of the vibration isolation table. By controlling the acceleration / deceleration of the mechanism, the control performance of the stage can be improved by avoiding the influence of the natural vibration of the vibration isolation table.
[0012]
Further, the present invention is characterized in that the acceleration time or the deceleration time is a time excluding a frequency cycle in which the vibration transmissibility of the vibration isolation table exceeds a half value of the maximum value.
According to the present invention, not only the maximum value of the vibration transmissibility, but also the frequency period and the acceleration / deceleration time that are greatly influenced by resonance do not coincide with each other, so that the control performance of the stage can be further improved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of an exposure apparatus 10 according to an embodiment. The exposure apparatus 10 includes a mask M on which a liquid crystal display element pattern is formed and a glass plate (hereinafter referred to as “plate”) P as a substrate (and an object) held on a plate stage PST as a first stage. By performing relative scanning in the same direction at the same speed along the first direction with respect to the projection optical system PL, that is, a predetermined scanning direction (here, the X-axis direction in FIG. The scanning exposure apparatus for liquid crystal of the same size batch transfer type that transfers the pattern formed on the mask M onto the plate P. The exposure apparatus 10 illuminates a predetermined slit-shaped illumination area (a rectangular area or an arc-shaped area elongated in the Y-axis direction (perpendicular to the plane of FIG. 1) on the mask M with the exposure illumination light IL. The system IOP, the mask stage MST as a second stage that moves in the X-axis direction while holding the mask M on which the pattern is formed, and the exposure illumination light IL transmitted through the illumination area portion of the mask M are projected onto the plate P A main body column 12 for holding the projection optical system PL, a vibration isolator 17 for removing vibration from the floor, a control device 11 for controlling both the stages MST and PST, and the like are provided.
[0014]
The illumination system IOP includes, for example, a light source unit, a shutter, a secondary light forming optical system, a beam splitter, a condensing lens system, a field stop (blind), and a picture image as disclosed in JP-A-9-320956. The slit illumination area on the mask M, which is composed of a lens system and the like (both not shown) and is placed and held on the mask stage MST described below, is illuminated with uniform illuminance.
[0015]
The mask stage MST is levitated and supported above the upper surface of the upper surface plate 12a constituting the main body column 12 by a not-shown air pad via a clearance of about several μm, and is driven in the X-axis direction by the drive mechanism 14. The
[0016]
Since a linear motor is used here as the drive mechanism 14 for driving the mask stage MST, this drive mechanism is hereinafter referred to as a linear motor 14. The stator 14a of the linear motor 14 is fixed to the upper part of the upper surface plate 12a and extends along the X-axis direction. The mover 14b of the linear motor 14 is fixed to the mask stage MST. The position of the mask stage MST in the X-axis direction is determined by a mask stage position measuring laser interferometer (hereinafter referred to as “mask interferometer”) 18 fixed to the main body column 12 with reference to the projection optical system PL. It is constantly measured with a resolution, for example, a resolution of about several nm. The X-axis position information S3 of the mask stage MST measured by the mask interferometer 18 is supplied to the control device 11 (see FIG. 2).
[0017]
The projection optical system PL is disposed below the upper surface plate 12 a of the main body column 12 and is held by a holding member 12 c constituting the main body column 12. Here, as the projection optical system PL, an apparatus that projects an equal-size erect image is used. Therefore, when the slit illumination area on the mask M is illuminated by the exposure illumination light IL from the illumination system IOP, an equal-magnification image (partial upright image) of the circuit pattern of the illumination area is displayed on the plate P. It is projected onto the exposure area conjugate to the illumination area. For example, as disclosed in Japanese Patent Application Laid-Open No. 7-57986, the projection optical system PL may be configured by a plurality of sets of equal-magnification projection optical system units.
[0018]
The plate stage PST is disposed below the projection optical system PL, and is levitated and supported by a not-shown air pad above the upper surface of the lower surface plate 12b constituting the main body column 12 via a clearance of about several μm. Yes. The plate stage PST is driven in the X-axis direction by a linear motor 16 as a drive mechanism. The stator 16a of the linear motor 16 is fixed to the lower surface plate 12b and extends along the X-axis direction. A movable element 16b as a movable part of the linear motor 16 is fixed to the bottom of the plate stage PST. The plate stage PST includes a moving table 22 as a first portion to which the mover 16b of the linear motor 16 is fixed, a Z / θ driving mechanism 20 mounted on the moving table 22, and the Z / θ driving mechanism. The second part placed on the upper part of 20 is placed and fixed by suction via a vacuum chuck (not shown). The substrate table 19 is finely driven in the vertical direction and the rotational direction by a Z / θ drive mechanism 20.
[0019]
The position of the substrate table 19 in the X-axis direction is a predetermined resolution with respect to the projection optical system PL as a reference by a plate interferometer 25 as a first position measuring device fixed to the main body column 12, for example, about several nm. Always measured with resolution. As the plate interferometer 25, here, two length measuring beams in the X-axis direction separated by a predetermined distance L in the Y-axis direction orthogonal to the X-axis direction (the direction orthogonal to the paper surface in FIG. 1) are used as the substrate table 19. A two-axis interferometer that irradiates the light is used, and the measurement values of each measurement axis are supplied to the control device 11 (and a main control device (not shown) via this). When the measured values of the length measuring axes of the plate interferometer 25 are X1 and X2, the position of the substrate table 19 in the X-axis direction is obtained by X = (X1 + X2) / 2, and θ = (X1-X2) / L The amount of rotation of the substrate table 19 around the Z-axis can be obtained. However, in the following description, the X described above is used as the X position information S1 of the substrate table 19 from the plate interferometer 25 unless otherwise required. Shall be output.
[0020]
Further, in the present embodiment, a focus position detection system (not shown) that measures the position of the plate P in the Z direction, for example, a grazing incidence light focus position detection system is fixed to the holding member 12c that holds the projection optical system PL. The Z position information of the plate P from the focal position detection system is supplied to a main controller (not shown). The main controller, for example, uses the Z / θ drive mechanism 20 based on the Z position information during scanning exposure. An autofocus operation is performed to match the Z position of the plate P with the imaging plane of the projection optical system PL.
[0021]
In the main controller, the rotation of the plate P during scanning exposure is controlled via the Z · θ drive mechanism 20 based on the above θ (rotation amount around the Z axis), or the mask M and the plate P The rotation of the plate P is controlled via the Z · θ drive mechanism 20 based on the rotation error of both obtained from the alignment result.
[0022]
Next, with reference to FIGS. 2 and 3, a stage control device mainly composed of the control device 11 and a control system equivalent to the stage control device will be described. FIG. 2 is a block diagram showing a configuration of a stage control device configured with the control device 11 as a center, and FIG. 3 is a control block diagram showing a configuration of a control system equivalent to the stage control device.
[0023]
The control device 11 includes a target value output unit 26 that outputs a target position Pref, a command speed Vref, and a command acceleration αref, a target position Pref output from the target value output unit 26, and plate interferometer information S1, that is, a substrate table 19. A subtractor 28 for calculating a difference (positional deviation) from the current position in the X direction, and a plate stage to which an output from the subtracter 28 and a command speed Vref input from the target value output unit 26 are input. The servo calculation unit 32, an adder 55 for adding the output of the plate stage calculation unit 32 and the control amount corresponding to the command acceleration αref fed forward from the target value output unit 26, and the output of the adder 55 A plate stage drive amplifier 36 which converts the plate stage drive signal S2 to be applied to the linear motor 16; And a differentiator 40 for subtracting the information S1 and inputting it to the plate stage servo calculation unit 32. The differencer 40 obtains the time change rate of the position information S1, that is, the speed of the substrate table 19, by dividing the difference between the value at the previous sampling and the value at the current sampling by the sampling clock interval.
[0024]
Further, the control device 11 inputs the X position information S1 output from the plate interferometer 25 and the X position information S3 output from the mask interferometer 18, and the substrate table 19 and the mask stage which are the difference between the two are input. A subtractor 44 for calculating the positional deviation in the X-axis direction from the MST, a mask stage servo calculation unit 46 to which an output from the subtractor 44 is input, and an output of the mask stage servo calculation unit 46 as a mask stage drive signal And a mask stage drive amplifier 48 which converts the signal into S4 and applies it to the linear motor 14.
[0025]
For example, as shown in FIG. 3, the plate stage servo calculation unit 32 performs a (proportional) control operation using the position deviation from the subtractor 28 as an operation signal, and is output from the P controller 50. A subtractor 52 for calculating a speed deviation which is a difference between the speed command value and the output of the integrator 56 of FIG. 3 corresponding to the output of the subtractor 40 of FIG. 2, that is, the current speed of the substrate table 19, and the subtractor 52 And a PI controller 54 that performs a control operation combining (proportional + integral) control operation (PI control operation) and phase advance compensation control using the speed deviation output from the adder 53 as an operation signal. And can be configured.
Note that the PI controller 54 includes a phase advance compensation circuit, for example, a CR circuit.
[0026]
In the present embodiment, the plate stage shown in FIG. 3 by the plate interferometer 25, subtractor 28, subtractor 40, plate stage servo calculation unit 32, plate stage drive amplifier 36 and linear motor 16 shown in FIG. A multiplex having a position control loop LLI that performs proportional control of the position of the PST, and a speed control loop LL2 that performs a control operation combining the PI control operation and the phase advance compensation control that constitute the inner loop (minor loop). A loop control system L1 is configured. The multiple loop control system L1 constitutes a plate stage position / speed control system L1 as a first stage control system. Here, the reason why the plate stage position / speed control system L1 is a multi-loop control system is to improve the steady speed deviation, for example.
[0027]
For example, as shown in FIG. 3, the mask stage servo calculation unit 46 can be configured by a PI controller that performs a PI control operation using the position deviation from the subtractor 44 as an operation signal.
[0028]
In this embodiment, the mask interferometer 18, the subtractor 44, the mask stage servo calculation unit 46, the mask stage drive amplifier 48, and the linear motor 14 shown in FIG. A mask stage position control system L2 is configured as a second stage control system for controlling the position of the mask stage MST by regarding the X position information S1 of the substrate table 19 as a target value. By this mask stage position control system L2, follow-up control of the mask stage MST with respect to the plate stage PST is performed using the X position information S1 of the substrate table 19 as a target value input. For the same reason as described above, the mask stage control system may be a multi-loop control system similar to the plate stage position / speed control system L1.
[0029]
Of course, the control device 11 may be constituted by a microcomputer, and the functions of the respective units in FIG. 2 may be realized by software or firmware of the microcomputer.
[0030]
Here, a specific control operation of the plate stage position / speed control system L1 will be described with reference to FIG. When a signal of the target position Pref of the plate stage PST is output from the target value output unit 26, the difference between the target position Pref and the X position information S1 from the first substrate stage interferometer 25 is obtained by the subtractor 28. The position deviation is calculated, and the P controller 50 performs a proportional control operation using the position deviation as an operation signal. As a result, the speed command value is given from the P controller 50 to the subtractor 52.
[0031]
In the subtractor 52, the speed command value and the current speed of the substrate table 19 which is the output of the integrating circuit 56 in FIG. 3 (actually the previous sampling value of the position of the substrate table 19 calculated by the differencer 40 in FIG. 2). The speed deviation, which is the difference between the substrate table speeds obtained by the sampling value difference this time, is calculated, the adder 53 adds the speed deviation and the command speed Vref, and the speed deviation obtained by adding the command achievement Vref is obtained. As an operation signal, the PI controller 54 performs a control operation combining the PI control operation and the phase advance compensation control. As a result, a predetermined thrust command value (control amount) is output from the PI controller 54 to the adder 55.
[0032]
In the adder 55, the command acceleration αref is converted by the action of the gain Mp / K1 (this is a gain corresponding to a value obtained by dividing the mass Mp of the plate stage PST by a thrust conversion gain K1 described later). The command value (control amount) is input. The adder 55 adds the output from the gain Mp / K1 and the output of the plate stage servo calculation unit 32. Then, the control amount (thrust command value) that is the output of the adder 55 is converted into the force F by the thrust conversion gain K1. As apparent from FIG. 3, this force F is the thrust conversion value of the output of the plate stage servo calculation unit 32 and the thrust conversion value (Mp · αref) of the command acceleration αref fed forward from the target value output unit 26. ).
[0033]
Here, the correspondence between the operation of the thrust conversion gain K1 and the actual phenomenon will be described. The thrust command value from the adder 55 is given to the plate stage drive amplifier 36 in FIG. This is equivalent to the drive signal S2 being given to the linear motor 16 and the linear motor 16 generating the thrust F.
[0034]
Then, the plate stage PST is driven in the X-axis direction with an acceleration α corresponding to the thrust (F). In other words, this phenomenon of driving the plate stage PST is equivalent to the above-described thrust F being converted into the acceleration α by the action of the gain (1 / Mp) corresponding to the reciprocal of the mass of the plate stage PST. In this sense, the gain (1 / Mp) is shown as a component of the control system in FIG.
[0035]
Then, the acceleration α is sequentially converted into speed and position by the integrators 56 and 58, the speed information is fed back to the subtractor 52, and the position information S1 is fed back to the subtractor 28. The position / velocity of the plate stage PST such that the position deviation, which is the difference between the target position Pref and the position information S1 from the first substrate table interferometer 25, becomes zero by the plate stage position / speed control loop L1. Control is performed.
[0036]
As described above, in this embodiment, in addition to the target position Pref, the command speed Vref and the command acceleration αref are fed forward to the plate stage position / speed control system L1 (see FIG. 3). This is because the control performance of the entire system including the plate stage PST is improved by controlling the plate stage PST by feeding forward speed and acceleration in addition to the feedback loop of the position of the plate stage, and the plate stage by the control device 11 This is intended to further improve the controllability of the PST, for example, the position control response.
[0037]
The integrators 56 and 58 in FIG. 3 do not actually exist, the speed signal that is the output of the integrator 56 is the output of the difference unit 40, and the output S 1 of the integrator 58 is the output of the interferometer 25. In FIG. 3, the integrators 56 and 58 are illustrated in accordance with the convention of writing a control block diagram.
[0038]
Next, a specific control operation of the mask stage position control system L2 will be described based on FIG. 3 with reference to FIG. 2 as appropriate. When the position information S1 is input from the plate interferometer 25 to the subtractor 44, the subtractor 44 calculates a position deviation which is a difference between the position information S1 and the X position information S3 from the mask interferometer 18. Next, the PI controller 46 performs a PI control operation using the position deviation as an operation signal, and as a result, a predetermined control amount (a control amount corresponding to the mask stage drive signal S4 in FIG. 2) is output from the PI controller 46. . Then, this control amount is converted into a force F ′ by the thrust conversion gain K2. Explaining the correspondence between the operation of the thrust conversion gain K2 and the actual phenomenon, a predetermined control amount is given from the PI controller 46 to the mask stage drive amplifier 48 of FIG. 2, and the mask stage drive signal S4 from the amplifier 48 is obtained. This is equivalent to the linear motor 14 generating a thrust F ′.
[0039]
Then, the mask stage MST is driven in the X-axis direction with β corresponding to the thrust (F ′). In other words, this phenomenon of driving the mask stage MST is equivalent to the above-described thrust F ′ being converted into the acceleration β by the action of the gain (1 / Mm) corresponding to the reciprocal of the mass of the mask stage MST. In this sense, FIG. 3 shows the gain (1 / Mm) as a component of the control system.
[0040]
Then, the acceleration β is sequentially converted into a speed and a position by the integrators 60 and 62, and the position information S3 is fed back to the subtractor 44. In this manner, the mask stage position control loop L2 causes the plate The follow-up control of the mask stage MST with respect to the plate stage PST is performed so that the position deviation, which is the difference between the position information S1 from the interferometer 25 and the position information S3 from the mask interferometer 18, becomes zero.
[0041]
Here, with reference to FIG. 4, the vibration transfer characteristics of the vibration isolation tables 17a and 17b shown in FIG. 1 will be briefly described. FIG. 4 is a diagram showing the vibration transmission characteristics of the vibration isolation tables 17a and 17b using the air damper. As shown in FIG. 4, the vibration isolation tables 17a and 17b have a maximum vibration transmissibility near the vibration frequency of 3 [Hz], and this frequency becomes the natural frequency of the vibration isolation tables 17a and 17b. When a vibration corresponding to this natural frequency is externally applied to the vibration isolation table, the vibration may be excited (amplified). If a vibration source having a frequency in the vicinity of the natural frequency can be eliminated, adverse effects caused by excitation (amplification) of vibration can be prevented.
[0042]
In the exposure apparatus 10 of the present embodiment, during scanning exposure, a constant stage control of the plate stage PST (master stage) and a mask stage MST (slave) for the plate stage PST are performed by a stage control apparatus equivalent to the control system of FIG. Stage) follow-up control is performed based on the target position (corresponding to the acceleration command) from the target value output unit 26. At this time, the target value output unit 26 determines and outputs the acceleration / deceleration so that the acceleration / deceleration time when the plate stage PST as the master stage is driven does not coincide with the natural vibration period of the vibration isolation bases 17a and 17b. If this is performed, the influence of vibration can be minimized.
[0043]
The target value output unit 26 determines the acceleration / deceleration time according to the target acceleration output when driving the plate stage PST as the master stage according to the vibration transfer characteristics of the vibration isolation tables 17a and 17b to be used. Within the range of the frequency (0.5 to 0.25 [s]) of the frequency of the vibration transmissibility exceeding the half value of the maximum transmissibility (approximately 2 to 4 [Hz] in the example shown in FIG. 4) By avoiding this, target value output that minimizes the influence of vibration is performed.
[0044]
At that time, when the scanning speed given from the upper level is 250 [mm / s] or more, the average acceleration at acceleration (deceleration) is 500 [mm / s. ² ] Fixed. When the scanning speed given from the upper level is less than 250 [mm / s], the average acceleration during acceleration (deceleration) is set to a value twice the scanning speed value. This value is determined by referring to a target value table provided in advance in the target value output unit 26. FIG. 5 shows an example of the table structure of the target value table when the instruction value given from the host is the scan speed. FIG. 5 shows an example in which the average acceleration / deceleration value is divided depending on whether the scan speed is 250 or more. This value of “250” is an average acceleration / deceleration (500 [mm / s in this example) that can maximize the capability of the mechanism that drives each stage. ² ]), The lower limit value of the frequency cycle of the vibration transmissibility exceeding 0.5 times the maximum value of the vibration transmissibility of the vibration isolation table (here, 0.5 [s]) ). In FIG. 5, the upper limit value of the scan speed is 300 [mm / s], which is the maximum value that the drive mechanism has.
[0045]
By doing in this way, the scanning speed is 250 [mm / s] or more, and the average acceleration during acceleration (decreasing) is 500 [mm / s. ² ], The acceleration (deceleration) speed time is 0.5 [s] or more, and therefore the frequency period (0.5 to 0.25 [s]) is in the vicinity of the natural frequency of the vibration isolation table. It does not excite the natural vibration of the vibration isolation table. Further, when the scanning speed is 200 [mm / s] less than 250 [mm / s], the average acceleration during acceleration (deceleration) is a value twice the scanning speed value (400 [mm / s). ² ]), The acceleration (deceleration) acceleration time is fixed to 0.5 seconds, and is not in the range of the frequency period (0.5 to 0.25 [s]) near the natural frequency of the vibration isolation table. And does not excite the natural vibration of the vibration isolation table.
[0046]
Further, in the exposure apparatus 10 of the present embodiment, during the step movement, the stage control device equivalent to the control system described above performs PTP control (point-to-point control) of the plate stage PST and tracking of the mask stage with respect to the plate stage PST. Control is performed based on the target position (corresponding to the acceleration command) from the target value output unit 26.
[0047]
At this time, when the step moving distance given from the upper level is 360 [mm] or more, the maximum speed is fixed at 600 [mm / s], and the average acceleration at acceleration (deceleration) is 1000 [mm / s. ² ] Fixed. When the step movement distance is less than 360 mm, the maximum speed is obtained by dividing the value of the step movement distance by 0.6, and the average acceleration during acceleration (deceleration) is multiplied by 0.833. Value. This value is determined by referring to a target value table provided in advance in the target value output unit 26. FIG. 6 shows an example of the table structure of the target value table when the instruction value given from the host is the step movement distance. Also in this example, the case is divided depending on whether the step moving distance is 360 or more. This value is the acceleration / deceleration time 1 / of the maximum vibration transmissibility of the vibration isolation table when driving at the maximum speed and average acceleration / deceleration that can maximize the capabilities of the mechanism that drives each stage. It is a value determined so as not to be in the range of the frequency cycle of vibration transmissibility exceeding the value of 2.
[0048]
Even in this case, the acceleration (deceleration) speed time is fixed to 0.6 seconds, and the frequency period (0.5 to 0.25 [s]) in the vicinity of the natural frequency of the vibration isolation table is not within the range. And does not excite the natural vibration of the vibration isolation table.
[0049]
In this way, since the natural vibration of the vibration isolation table is prevented from being excited during acceleration / deceleration of the scanning operation or step operation, the overshoot and undershoot after the plate stage acceleration / deceleration is completed can be reduced. Follow-up performance and settling performance can be improved. The target value table may be appropriately set based on the capability of the drive mechanism or the like even when further dividing the case or changing the threshold value.
[0050]
When the plate stage PST that is the master stage and the mask stage MST that is the slave stage operate synchronously, when performing exposure at the same magnification, the acceleration / deceleration time of the master stage matches the period of the natural frequency. As a result, the acceleration / deceleration time of the slave stage does not coincide with the natural frequency cycle, so that the target value described above can be obtained only when outputting the target value of the plate stage as the master stage. You can refer to the table.
[0051]
On the other hand, when the master stage and the slave stage operate synchronously, when performing exposure that is not the same size (for example, 4 times), control is performed so that the acceleration / deceleration time of the master stage does not coincide with the period of the natural frequency. If this is done, there is a possibility that the acceleration / deceleration time of the slave stage matches the period of the natural frequency. In this case, a plurality of target value tables for equal magnification, a target value table for four times,..., A target value table for magnification are prepared in advance, and can be selected and used according to a request given from the host. Good.
In the case of performing reduced exposure (for example, 1/4 times or 1/2 times), it is the same that the control is performed so that the cycle of each drive mechanism does not coincide with the cycle of the natural frequency.
[0052]
In the above description, the control of the XY stage has been described. However, when the instruction value given from the host is the step movement amount of the θ stage, the target value in which the step movement amount, the maximum speed, and the average acceleration / deceleration are associated with each other. If a table is provided in the target value output unit 26 and the maximum speed and average acceleration / deceleration obtained by referring to the target value table are set as target values, the present invention can also be applied to the control of the θ stage. Furthermore, this control method is applicable not only to the stage drive mechanism but also to any drive mechanism on the vibration isolation table. That is, if the acceleration / deceleration time of the drive mechanism is controlled so that the acceleration / deceleration is adjusted within a possible range so that it does not coincide with the natural frequency of the vibration isolation table, the follow-up performance and settling of the drive mechanism can be achieved without amplifying vibration Performance can be improved.
[0053]
In the above embodiment, the exposure apparatus in which the mask stage MST and the plate stage PST are fixed to the main body column 12 has been described as an example. However, each of the mask stage MST and the plate stage PST is mounted on an independent vibration isolation table. The above-described method for controlling the stage apparatus can be applied even to the exposure apparatus placed. FIG. 7 is a schematic view of an exposure apparatus in which each of the mask stage MST and the plate stage PST is placed on an independent vibration isolation table. In the exposure apparatus shown in FIG. 7, a mask stage MST that holds and moves a mask M is placed on vibration isolation tables 17 c and 17 d installed on a main body column 12, and a plate stage that holds and moves a plate P. The PST is placed on the vibration isolation tables 17e and 17f installed on the floor. The projection optical system PL is also placed on the vibration isolation tables 17g and 17h. In the exposure apparatus having such a configuration, since the mask stage MST and the plate stage PST are mounted on different vibration isolation tables, a target value to be output when each stage is driven is determined. Sometimes, a different target value table is prepared for each vibration isolation table, and if the output target value is determined with reference to this target value table, the generated vibration of each stage is not amplified. It is possible to perform drive control.
[0054]
Further, only the range of the cycle to be avoided (for example, the cycle of the frequency of the vibration transmissibility exceeding the half value of the maximum value of the vibration transmissibility) is held in the target value output unit 26, and the target value When the target value obtained in the output unit 26 matches the cycle to be avoided, the average acceleration / deceleration, the maximum speed, etc. are changed within a possible range, and the acceleration / deceleration time does not match the cycle to be avoided. Thus, the average acceleration / deceleration and the maximum speed may be calculated internally.
[0055]
In the above embodiment, the case where the present invention is applied to a scanning exposure apparatus for liquid crystal of the same size batch transfer type has been described. However, the present invention is not limited to this, and is not limited to this. The present invention can be suitably applied not only to scanning scanning steppers for wave crystals, but also to exposure apparatuses such as semiconductor manufacturing steppers and scanning steppers. The present invention can also be applied to a vertical exposure apparatus that holds the mask M and the plate P along the vertical direction.
[0056]
As described above, according to the stage apparatus according to the present invention, the position control performance of the substrate stage can be improved. Therefore, the present invention is applied particularly to a sequential movement type exposure apparatus such as a stepper and a scanning stepper. In this case, it is possible to improve throughput and positioning performance even during stepping between shots and when moving to an alignment position.
[0057]
In addition to the above, in addition to exposure apparatuses such as an electron beam exposure apparatus and an X-ray exposure apparatus, the stage apparatus according to the present invention also includes an apparatus including a substrate stage that holds and moves a substrate, such as a laser repair apparatus. Applicable.
[0058]
A program for realizing the function of the target value output unit 26 shown in FIG. 2 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. Control processing of the stage device may be performed. The “computer system” here includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.
[0059]
The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.
[0060]
【The invention's effect】
As described above, according to the present invention, the acceleration time or deceleration time of the stage drive mechanism that may become a vibration source that resonates with the natural frequency of the vibration isolation table is the period of the natural frequency of the vibration isolation table. By controlling the acceleration / deceleration of the drive mechanism so as not to coincide with the above, it is possible to avoid the influence of the natural vibration of the vibration isolation table and improve the stage control performance.
In addition, according to the present invention, since the stage apparatus capable of improving the control performance of the stage is provided, an effect that the throughput and the pattern transfer accuracy can be improved can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing the arrangement of an exposure apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a stage control device configured around the control device shown in FIG. 1;
FIG. 3 is a control block diagram showing a control system equivalent to the stage control device shown in FIG. 2;
FIG. 4 is a diagram illustrating vibration transfer characteristics of a vibration isolation table.
FIG. 5 is an explanatory diagram showing a table structure of a target value table provided in the target value output unit 26 shown in FIG. 2;
6 is an explanatory diagram showing a table structure of a target value table provided in the target value output unit 26 shown in FIG. 2. FIG.
FIG. 7 is a schematic view showing the arrangement of another exposure apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus, 17a, 17b ... Vibration isolator, 26 ... Target value output part, PST ... Plate stage (first stage), L1 ... Plate stage position / speed control system (first stage control system), MST ... Mask stage (second stage), L2 ... Mask stage position control system (second stage control system), P ... Plate (object, substrate), M ... Mask

Claims (7)

A stage apparatus comprising a stage capable of holding and moving an object and a drive mechanism for driving the stage on a vibration isolation table for removing vibrations,
A stage apparatus comprising control means for controlling the acceleration / deceleration of the drive mechanism while avoiding coincidence between the natural vibration period of the vibration isolation table and the acceleration time or deceleration time of the drive mechanism. The control means includes
A data table in which an instruction value related to driving of the stage and a drive target value for avoiding the natural vibration period are associated in advance;
2. The stage according to claim 1, wherein a drive target value associated with an instruction value given from a host is obtained by referring to the data table, and the drive mechanism is controlled based on the drive target value. apparatus. The acceleration time or deceleration time is
The stage apparatus according to claim 1, wherein the vibration removal rate of the vibration isolation table is a time period that excludes a period of a frequency that exceeds a half value of the maximum value. An exposure apparatus for transferring a predetermined pattern onto a substrate,
An exposure apparatus comprising the stage apparatus according to claim 1, wherein the substrate is placed on the stage. An exposure apparatus that synchronously moves a mask and a substrate to transfer a pattern of the mask onto the substrate,
A master stage on which the substrate is placed;
A slave stage on which the mask is mounted and follows the master stage;
With
An exposure apparatus, wherein the master stage is the stage apparatus according to any one of claims 1 to 3. A method for controlling a stage apparatus comprising a stage capable of holding and moving an object and a drive mechanism for driving the stage on a vibration isolation table for removing vibrations,
A control method for a stage apparatus, comprising: a control process for controlling acceleration / deceleration of the drive mechanism while avoiding coincidence between a natural vibration period of the vibration isolation table and an acceleration time or a deceleration time of the drive mechanism. The acceleration time or deceleration time is
7. The method for controlling a stage apparatus according to claim 6, wherein the period is a time for excluding a frequency cycle in which the vibration transmissibility of the vibration isolation table exceeds a half value of the maximum value.

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