JP2001267220A - Stage device and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To swing a table at a high speed without making the setting time longer at the swinging time. SOLUTION: Stators 22b, 23b, and 24b of voice coil motors 22-24 are fixed to three sets of supporting pillars 21A-21C erected on a pedestal 21 and the needles 22a, 23a, and 24a of the motors 22-24 are fixed to a substrate table 12. The table 12 is supported by connecting the front ends of the pillars 21A-21C to the front end sections of the needles 22a, 23a, and 24a through plate springs 25-27. The position of the center of gravity of the table 12 along the Z-axis direction is nearly coincident with the position of the exposure surface of a wafer placed on the table 12 (the focal position of a projection optical system 9). The table 12 is swingingly driven around the center of gravity of the table 12 by means of the motors 22-24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stage device capable of changing a tilt angle by swinging a table on which a substrate such as a wafer is placed, and an exposure apparatus having the stage device.

[0002]

2. Description of the Related Art In a manufacturing process of a transparent substrate or a semiconductor element used for a liquid crystal display device, a photolithography technique using an exposure device is used. The exposure apparatus has an illumination optical system that illuminates a pattern of a mask, and a projection optical system that projects an image of the illuminated pattern onto a substrate to be exposed (hereinafter, a substrate). The substrate is the above-described wafer or transparent substrate, and a photoresist is applied on the exposure target. In such an exposure apparatus, a substrate stage on which a substrate is mounted is required to have high responsiveness in swing position control as described below.

The substrate is formed by sputtering or CVD.
In some cases, the film is exposed to a high temperature during a film forming process or the like. At this time, the substrate may be warped or undulated, and the exposure apparatus needs to perform exposure so as to reduce the influence of the warped or undulated.

For example, in an exposure system called a so-called scan exposure system, a part of a mask pattern is projected onto a substrate by a projection optical system, and the mask and the substrate are synchronously scanned relative to the projection optical system. The substrate is exposed with the entire image of the mask pattern. At this time, if the substrate has the aforementioned undulation or warpage, the orthogonality between the projection optical system and the exposure surface of the substrate cannot be maintained, and the line width of the pattern formed on the substrate may be varied.

[0005] In order to solve the above-mentioned problem, a technique called "chip leveling" has been conventionally used. For example, in the case of performing scan exposure, the above-described warpage or undulation of the substrate is measured in real time while performing scan exposure, and the table provided on the substrate stage is driven to swing in accordance with the measurement result. That is, even if the exposure surface is inclined due to the warpage or undulation of the substrate, the substrate table is driven to swing so that the exposure surface and the optical axis of the projection optical system are always orthogonal. At this time, the deviation in the optical axis direction between the focal position of the projection optical system and the exposure surface position on the substrate caused by the above-described substrate warpage or undulation is also corrected by driving the substrate table in the optical axis direction of the projection optical system. Is done.

In scan exposure, when the synchronous scanning speed of the mask and the substrate is slow to some extent, the above-described control of chip leveling is easy. However, the exposure apparatus is required to have a higher throughput year by year, and accordingly, the synchronous scanning speed is also increasing.

[0007]

However, as described above, the synchronous scanning speed is increased, and as the swinging speed at the time of swinging the substrate table for chip leveling is increased, the speed of the substrate table is increased. In some cases, the responsiveness of the swing position control is reduced, and it may be difficult to control the chip leveling with sufficient accuracy. Also, since the pivot axis of rotation of the substrate table is different from the image forming position of the projection optical system, when the substrate table is leveled, the exposure surface is shifted from the image forming position, and in some cases, the desired image forming performance cannot be obtained. There is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stage device having high responsiveness of swing position control and capable of high-speed and high-precision positioning. It is another object of the present invention to provide an exposure apparatus in which an exposure surface does not deviate from an image forming position of a projection optical system even when leveling is performed.

[0009]

The following invention will be described with reference to the drawings showing one embodiment. (1) A stage device according to the first aspect of the present invention has a table 12 on which a sample 10 is placed, a plurality of actuators 22 to 24, a swing device for swinging the table 12, and a table 12 And the control means 8 for controlling the plurality of actuators 22 to 24 so that the swinging rotation axis of the table 12 passes near the center of gravity of the table 12 when the actuators 22 to 24 are driven to swing. Achieve the above objectives. (2) According to a second aspect of the present invention, in the stage device according to the first aspect, the swing device has a plurality of leaf springs 25 to 27 connected to the plurality of actuators 22 to 24. I do. (3) The invention according to claim 3 is the stage device according to claim 1 or 2, wherein the plurality of actuators 22 are provided.
-24 are movable elements 22a-2 provided on the table 12.
4a and a stator 2 cooperating with its movers 22a to 24a
2b to 24b. (4) In an exposure apparatus for exposing the pattern of the mask 3 onto the substrate 10, the projection optical system 9 having a predetermined imaging characteristic and projecting the pattern onto the substrate 10 is provided.
And a substrate table 12 on which the substrate 10 is placed, so that the position of the center of gravity of the substrate table 12 and the image forming position of the projection optical system 9 substantially match each other, thereby achieving the object described above. (5) The invention according to claim 5 is the exposure apparatus according to claim 4, comprising a plurality of actuators 22 to 24,
A swinging device for swinging and driving the substrate table; and a control means for controlling a plurality of actuators to so that the swinging rotation axis of the substrate table passes near the center of gravity of the substrate table. It is characterized by. (6) According to a sixth aspect of the present invention, in the exposure apparatus according to the fifth aspect, the swing device has a plurality of leaf springs 25 to 27, and the center of the thickness of the plurality of leaf springs 25 to 27 is projected. It is characterized by being substantially coincident with the image forming position of the optical system 9.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used for easy understanding of the present invention. However, the present invention is not limited to this.

[0011]

FIG. 1 shows a schematic structure of an exposure apparatus having a stage device according to the present invention. An exposure apparatus that exposes a wafer with a reticle pattern image will be described below. It should be noted that the X axis in the horizontal direction of FIG.
The Z axis is taken in the vertical direction, and the Y axis is taken in the direction perpendicular to the plane of the paper. The directions along these coordinate axes are defined as X, Y, and Z directions, respectively. The directions in which the coordinate values increase are defined as the plus X direction, the plus Y direction, and the plus Z direction, and the directions in which the coordinate values decrease are defined as the minus X direction, the minus Y direction, and the minus Z direction. Further, directions around a rotation axis parallel to these axes are defined as directions around an X axis, directions around a Y axis, and directions around a Z axis.

In FIG. 1, illumination light for exposure emitted from a pulse oscillation type light source 1 such as an excimer laser is incident on an illumination optical system 2. The illumination optical system 2 converts the incident illumination light into exposure light IL having a uniform illuminance distribution, and the exposure light IL illuminates the reticle 3. The illumination optical system 2 includes a beam shaping optical system, a dimming optical system, an optical integrator, a field stop, a condenser lens, and the like. A semiconductor circuit pattern, a liquid crystal element pattern, and the like are formed on the reticle 3, and transmitted light transmitted through the pattern is projected onto a wafer 10 by a projection optical system 9. Wafer 10
Is coated with a photoresist, and the resist is exposed with the projected pattern image to form a latent image.

The reticle 3 is held and fixed on a mask stage 4, and the mask stage 4 has an optical axis AX of a projection optical system 9.
Are movable in the ± X direction and the ± Y direction in a plane perpendicular to the plane. During exposure, the reticle 3 is moved by the mask stage 4 in the plus X direction and the minus X direction. A movable mirror 6 is fixed on the mask stage 4, a laser beam emitted from a laser interferometer 7 is applied to the movable mirror 6, and the reflected beam is received by the interferometer 7, and the coordinate position of the mask stage 4 in the X direction is received. Is measured. The X-direction position coordinates are input as a signal S1 to a main control system 8 which controls the entire exposure apparatus. Although not shown, a moving mirror and a laser interferometer for measuring the Y-direction position coordinates of the mask stage 4 are also provided, and the Y-direction position coordinates are also stored in the main control system 8.
Is input to The main control system 8 is a mask stage controller 4
The position and the moving speed of the reticle 3 are controlled by controlling a stage drive source such as a linear motor via a.

On the lower surface of the mask stage 4, a reticle blind 5 having a rectangular opening 5a is provided.
By the opening 5a of the reticle blind 5, a rectangular illumination area is set on the reticle 3. The reticle blind 5 may be provided on the upper surface of the mask stage 4.

[0015] Of the patterns drawn on the reticle 3 through the projection optical system 9 disposed below the reticle blind 5, a pattern image in the illumination area limited by the opening 5a of the reticle blind 5 is formed on the wafer 10. Projected above.
That is, at any time, the reticle blind 5
A region located at a position conjugate with respect to the projection optical system 9 with respect to the position of the illumination region on the reticle 3 limited by the opening 5a is a rectangular exposure region on the wafer 10.

The wafer 10 is held and fixed on a table 12 of a substrate stage ST via a wafer holder (not shown). The substrate table 12 has voice coil motors (VCM) 22, 23, 24 capable of generating thrust in the ± Z direction.
(The VCM 24 disposed at a position on the back side of the paper is not shown), and is fixed to the base 21. The pedestal 21 is fixed on an XY stage 13 that can move in the X and Y directions. The VCMs 22, 23, and 24 are controlled by the stage controller 16. The substrate table 12
Is fixed to the pedestal 21 via the VCMs 22, 23 and 24 will be described later in detail.

The XY stage 13 includes an X stage for scanning the substrate table 12 in the X direction together with the pedestal 21 and a Y stage for scanning in the Y direction (both are not shown). The X stage and the Y stage are held by air bearings, and are provided on a base so as to move in both X and Y directions by a linear motor, for example.

On the substrate table 12, a movable mirror 1 for the X axis is provided.
A moving mirror (not shown) for 2 m and the Y axis is fixed, and a laser beam from an interferometer 15 fixed to the base is radiated toward the moving mirror 12 m, and the reflected beam is transmitted to the interferometer 15.
Receives light and measures the position of the substrate table 12 in the X direction.
The Y direction position of the substrate table 12 is measured similarly.
The X- and Y-direction position coordinates of the substrate table 12 thus measured are also input to the main control system 8. The main control system 8 controls a stage drive source 13M such as a linear motor via the wafer stage control device 16 and controls the drive of the XY stage 13 to control the position and the moving speed of the wafer 10.

Referring to FIGS. 2 and 3, substrate table 1 will be described.
The mounting structure 2 will be described in detail. FIG. 2 shows the substrate stage S
3A is a plan view of the substrate stage ST, FIG. 3B is a plan view of the pedestal 21, and FIG. 3C is a plan view of the substrate table 12. Z of the circular substrate table 12
The position of the center of gravity in the direction is determined so as to substantially coincide with the exposure surface of the wafer 10 placed on the substrate table 12.
A thick portion 12a is formed on the outer peripheral edge of the substrate table 12, and this shape is determined so that the position of the center of gravity of the substrate table 12 has the above-described positional relationship.

As shown in FIG. 3B, the pedestal 21
A support column 21A including a pair of columns 21a, a support column 21B including a pair of columns 21b, and a support column 21C including a pair of columns 21c are provided upright. These three sets of support columns 21A to 21C are arranged on a predetermined circumference at intervals of 120 degrees. As shown in FIG. 3 (b), a pair of columns 2
The stator 22b of the VCM 22 is provided between 1a. Similarly, a stator 23b of the VCM 23 is provided between the pair of columns 21b, and a VCM2 is provided between the pair of columns 21c.
Four stators 24b are provided. As can be seen from FIG. 2, the movers 22 are attached to the stators 22b, 23b and 24b.
a, 23a and 24a are respectively held. VCM
By applying a current of a predetermined polarity and a predetermined value to the VCMs 22 to 24, a repulsive force or an attractive force is generated from the VCMs 22 to 24 to the table 12 along the Z direction. VCM22-2
4 is controlled by the stage controller 16 (FIG. 1).

As shown in FIG. 3C, the substrate table 1
In FIG. 2, round holes 122a, 123a, 124a and a pair of rectangular holes 122b, 123b, 124b are opened at positions that divide the circumference of a predetermined radius around the center of gravity G into three equal parts. The shaft portions of the above-described VCM movers 22a, 23a, 24a (24a is not shown) are fitted into the round holes 122a, 123a, 124a. Rectangular hole 122b,
123b and 124b are provided with the above-described three pairs of columns 21a to 21b.
21c is loosely fitted. Therefore, the substrate table 1
2 is held by VCM movers 22a, 23a and 24a,
The position and inclination of the VCMs 22 to 24 in the Z direction are controlled by the position control in the Z axis direction.

As shown in FIGS. 2 and 3 (a), both ends of a leaf spring 25 are respectively connected to the tips of a pair of columns 21a, and the center of the leaf spring 25 contacts the tip of the mover 23a. (Consolidated). Similarly, both ends of the leaf spring 26 are connected to the tips of the pair of columns 21b, respectively, and the center of the leaf spring 26 contacts (couples) to the tip of the mover 23b. Furthermore, both ends of the leaf spring 27 are connected to the ends of the pair of columns 21c, respectively, and the central portion of the leaf spring 27 is in contact with (is connected to) the end of the mover 23c. In this way, the substrate table 12 is supported by the support columns 21A, 21B, 21C via the leaf springs 25, 26, 27. At this time, the position of the center of gravity of the substrate table 12 along the Z direction and the center of the thickness of the leaf springs 25, 26, 27 are Z
The dimensions of the support, the mover, and the like are determined so as to substantially match in the direction. That is, the image forming position of the projection optical system 9 and the center of the thickness of the leaf springs 25, 26, and 27 match in the Z direction.

FIG. 4 shows the above-mentioned leaf spring 25 (26, 2).
FIG. 4A is a view showing the appearance of FIG. 4A, and FIG. 4A shows a plan view thereof, and FIG. 4B shows a cross section BB of FIG. 4A. Since the leaf springs 25 to 27 all have the same appearance, the leaf spring 25 will be described. As shown in FIGS. 4A and 4B, the constricted portion N
Is provided. The constricted portion N is provided along both the plate width direction and the plate thickness direction as shown in FIGS. 4A and 4B. While the compliance of the leaf spring 25 is appropriately increased by the constricted portion N, a sufficient thickness and a plate width are secured at a joint portion between the pair of columns 21a, 21a and the mover 22a. Strength can be increased.

A total of four through holes 25a are provided at two locations on both sides of the leaf spring 25, and four through holes 25b are provided at the center. These through holes 25a and 25
b is a fixing hole for attaching the leaf spring 25 to the distal end portions of the pair of columns 21a and the mover 22a. Board table 1
When the plate 2 is driven to swing, the leaf spring 25 is deformed, but due to the shape of the leaf spring 25 described above, generation of an unnecessary large reaction force from the leaf spring 25 is suppressed.

Referring again to FIG. 1, below the projection optical system 9, there are provided oblique incidence type multi-point focal point detecting devices 19, 20 each comprising a light projecting device 19 and a light receiving device 20. ing. The light projecting device 19 projects a plurality of spot patterns, slit patterns, and other images obliquely with respect to the optical axis AX toward the exposure surface of the wafer 10 placed on the substrate table 12. The light receiving device 20 has a photoelectric sensor (not shown), and a reflected light beam from an image projected on the wafer 10 by the light projecting device 19 forms an image on the photoelectric sensor. The positions of at least three points in the Z direction on the surface of the wafer 10 are detected by the above-described focus position detection devices 19 and 20.

The scanning exposure performed by the exposure apparatus having the above-described configuration will be described. For example, when the projection optical system 9 is configured to project an inverted image at the projection magnification β, the reticle 3 scans the illumination area via the mask stage 4 in the + X direction or the −X direction at a speed VR. In synchronization with this, the wafer 10 is scanned via the X stage in the -X direction or + X direction, that is, in the direction opposite to the reticle 3 at the speed VW. Here, the wafer speed VW
Is represented by (1 / β) · VR.

The mask stage 4 during scan exposure
And the moving speed of the XY stage 13 on the wafer 10 side is:
The amount of pattern exposure light IL irradiated onto the reticle 3,
It is determined by the sensitivity of the photoresist applied to the opening 5a of the reticle blind 5 and the wafer 10, and the like. In other words, the movement of the mask stage 4 causes the pulse light transmitted through the pattern on the reticle 3 to cross the opening 5a of the reticle blind 5 within the time required for the wafer 10 to move.
The stage speed is determined and controlled so that the upper photoresist is sufficiently exposed.

At the time of the above-described scan exposure, the multipoint focus detecting devices 19 and 20
Of the exposure target area with respect to the optical axis AX and ± Z
Measure the position in the direction in real time. Then, information based on the measurement result is output to the arithmetic unit 18. The arithmetic unit 18 moves the substrate table 12 in the Z direction, which is necessary for making the exposure surface of the wafer 10 coincide with the focal position of the projection optical system 9 and making the optical axis AX orthogonal to the exposure surface. The direction and the swing angle (tilt amount) are obtained. The arithmetic unit 18 outputs to the main control system 8 information relating to the amount of movement of the substrate table 12 in the Z direction and the amount of tilt determined as described above.

The main control system 8 provides thrust generated by each of the VCMs 22 to 24 to the stage control device 16 based on information relating to the amount of movement of the substrate table 12 in the Z direction and the amount of tilt output from the arithmetic device 18. The command value corresponding to is output. At this time, the main control system 8 controls the substrate table 1
2 is tilted (oscillating drive), the substrate table 12
A command value corresponding to the thrust of each of the VCMs 22 to 24 is determined so that the thrust always swings around the center of gravity, and is output to the stage controller 16. The stage control device 16 independently controls a current flowing through each of the VCMs 22 to 24 based on a command value output from the main control system 16. Therefore, since the substrate table 12 of this embodiment is driven to swing around the center of gravity, the responsiveness of the swing position control is improved, and a stable swinging motion can be performed even when the swing speed increases. it can.

When the center of gravity of the substrate table does not coincide with the center of oscillation, when the substrate table is swung by the VCM, the substrate table vibrates according to the distance between the center axis of oscillation of the substrate table and the center of gravity. I do. Therefore, desired responsiveness cannot be obtained with respect to the swing position control, and a high positioning accuracy may not be obtained as the swing speed increases. In this regard, in the stage device according to the present embodiment, since the center of gravity of the substrate table and the center of swing are matched,
The vibration is suppressed, and the responsiveness regarding the noise position control can be improved.

Therefore, in the scanning exposure apparatus provided with the stage device according to the present invention, the speed of the scanning exposure can be increased, and high-speed and high-precision exposure can be performed. Therefore, even if the pattern formed on the substrate is miniaturized, it is possible to improve the throughput of the exposure apparatus while maintaining high exposure accuracy. Also, in the exposure apparatus of the batch exposure method, the positioning accuracy can be improved and the time required for the vibration of the substrate table to stabilize can be shortened, and the number of processed wafers per unit time can be increased.

In the above-described stage apparatus, since the focal plane of the projection optical system 9 and the position of the center of gravity of the substrate table coincide with each other, the X position of the exposure position generated when the substrate table is driven to swing around the center of gravity. , Y, and Z are minimized. Therefore, the time required for positioning the substrate table can be reduced, and the throughput of the exposure apparatus can be improved.

In the above, an example in which the stage apparatus according to the present invention is applied to a scanning type exposure apparatus has been described. However, a charged particle beam exposure apparatus, a batch exposure type exposure apparatus, an overlay accuracy measuring apparatus, a liquid crystal display panel, The present invention can be applied to various devices such as a so-called liquid crystal stepper that exposes a circuit pattern on a transparent substrate for a plasma display panel.

In the correspondence between the above-described embodiment and the claims, the wafer 10 is a sample and a substrate, the substrate table 12 is a table, the VCMs 22, 23, and 24 are actuators, and the main control system 8 is a control means. , Reticle 3 constitute a mask.

[0035]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first to third aspects of the present invention, when the table is oscillated by the plurality of actuators, the plurality of actuators are drive-controlled so that the oscillating rotation axis of the table passes near the center of gravity of the table. Therefore, the responsiveness of the swing position control is improved, and the swing drive speed of the table can be increased. (2) According to the fourth aspect of the present invention, since the position of the center of gravity of the substrate table and the image forming position of the projection optical system are substantially matched,
The amount of relative displacement between the substrate and the image of the pattern that occurs when the substrate table is swung can be minimized, and the imaging characteristics can be improved. (3) According to the fifth and sixth aspects of the present invention, the swing driving speed can be increased for the same reason as in the first to third aspects of the present invention. Can be completed in a short time, so that the processing capability of the exposure apparatus can be increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus having a stage device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a stage device according to the embodiment of the present invention.

3A is a longitudinal sectional view of a substrate stage, FIG. 3B is a plan view of a base, and FIG. 3C is a plan view of a table.

4A and 4B are diagrams for explaining the shape of a leaf spring, wherein FIG. 4A is a plan view and FIG.

[Explanation of symbols]

9 Projection optical system 10 Wafer 12 Substrate table 13 XY stage 21 Pedestal 21A-21C Support pillar 21a-21c Support pillar 22-24 VCM 22a, 23a, 24a Mover 22b, 23b, 23d Child 25, 26, 27 ... leaf spring

Claims (6)

[Claims] A swinging device having a table on which a sample is placed, a plurality of actuators for swinging the table, and swinging the table when the table is swingably driven by the actuator. Control means for controlling the plurality of actuators so that the rotation axis passes near the position of the center of gravity of the table. 2. The stage device according to claim 1, wherein the swing device has a plurality of leaf springs connected to the plurality of actuators. 3. The stage device according to claim 1, wherein the plurality of actuators include a mover provided on the table and a stator cooperating with the mover. Stage equipment. 4. An exposure apparatus for exposing a pattern of a mask onto a substrate, comprising: a projection optical system having a predetermined imaging characteristic and projecting the pattern onto the substrate; and a substrate table on which the substrate is mounted. An exposure apparatus, wherein a position of a center of gravity of the substrate table substantially coincides with an image forming position of the projection optical system. 5. An exposure apparatus according to claim 4, further comprising a plurality of actuators for swinging and driving said substrate table, wherein a swing rotation axis of said substrate table is near a center of gravity of said substrate table. Control means for controlling the plurality of actuators so as to pass through the exposure apparatus. 6. An exposure apparatus according to claim 5, wherein said oscillating device has a plurality of leaf springs, and a center of a thickness of said plurality of leaf springs substantially coincides with an image forming position of said projection optical system. An exposure apparatus.