JPH1140657A - Sample holding device and scanning-type aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sample-holding device, in which reticle is difficult to be shifted due to an inertial force at the time of acceleration/deceleration of a stage, and the surface of the sample can be fixed and held so as not to deviate. SOLUTION: A reticle is fixed and held by a sample-holding device 60 on a reticle stage 4 of a scanning-type scan aligner. The sample-holding device 60 is provided with a clamper 63, pivotally supported so as to be rotatable for interposing the reticle between the sample-holding device 60 and the stage 4. The clamper 63 is provided with pressurizing devices 70a-70c whose pressurizing force is independently adjustable. Each pressurizing device 70a-70c respectively interposes the different parts of the reticle. Even if undulation or projection and recession is present on the reticle, the reticle is precisely held and fixed on the reticle stage 4. A rotary shaft center 62 of the clamper 63 is made substantially coincident with the surface height of the reticle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample holding apparatus capable of holding, on a stage, a reticle or mask on which a semiconductor circuit pattern or a liquid crystal element pattern is formed, or a photosensitive substrate on which such a pattern is projected and exposed. Related to the device. The present invention also relates to a scanning exposure apparatus that moves a reticle or a mask and a sensitive substrate synchronously with a projection optical system interposed therebetween.

[0002]

2. Description of the Related Art For example, in a scanning type projection exposure apparatus which projects a reticle pattern onto a wafer by moving a reticle stage and a wafer stage in directions opposite to each other at a speed ratio corresponding to a projection reduction ratio, various patterns are formed. The formed reticle is mounted on the reticle stage by vacuum suction,
Wafers and glass substrates are also mounted on the substrate stage by vacuum suction. For example, a reticle is placed on a vacuum pad provided on a reticle stage, and the air above the vacuum pad is sucked by a compressor to attract the reticle to the reticle stage.

[0003]

However, when the stage moving speed is increased in order to improve the throughput, when the reticle is held by vacuum suction, the reticle deviates from a normal position due to the inertia force of the reticle stage. There is a risk that it will. Although it is conceivable to increase the area of vacuum suction in order to secure the suction force, there is not much room for increasing the area, and it is difficult to obtain a suction force sufficient to prevent displacement due to inertial force. And even if the reticle is slightly shifted, the alignment accuracy of the reticle is significantly reduced.

[0004] The present invention provides a sample holding device for holding a sample fixedly so that the surface of the sample is not distorted, and a scanning exposure apparatus provided with the sample holding device, in which the sample is hardly displaced by inertial force when the stage is accelerated and reduced. It is intended to provide a device.

[0005]

Means for Solving the Problems FIGS. 1 to 4 of an embodiment.
The present invention will be described with reference to FIG. (1) The invention of claim 1 is applied to a sample holding device 60 that holds a flat sample 3 placed on a stage 4 that can move in at least one direction. The above-mentioned object is achieved by providing a plurality of pressing devices 70a to 70c which can independently adjust the pressing force of a plurality of portions of the sample 3 and individually hold the pressing force to the stage 4. (2) As in the second aspect of the present invention, it is preferable to additionally provide a vacuum suction device for vacuum-sucking the sample 3. (3) The sample holding device 60 according to the third aspect of the present invention comprises the pressing devices 70a to 70
c, and the sample 3 is held between the stage 4 and the pressing devices 70 a to 70 c via the clamper 63. In this case, the rotation axis 62 of the clamper 63 is adjusted to the surface height of the sample 3. It is almost the same. (4) According to a fourth aspect of the present invention, the reticle 3 on which the pattern is formed is held by the sample holding device 60 according to any one of the first to third aspects, and the sensitive substrate 10 for exposing the pattern is held. Scanning for projecting a pattern onto the sensitive substrate 10 while moving the reticle stage 4 and the substrate stage 13 in synchronization with each other, comprising a substrate stage 13 and a projection optical system 9 for projecting illumination light transmitted through the reticle 3 onto the sensitive substrate 10. Mold exposure apparatus.

Although the present invention has been described in connection with the embodiments in the section of means for solving the above problems, the present invention is not limited to the embodiments.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A scanning exposure apparatus having a sample holding apparatus to which the present invention is applied will be described with reference to FIGS.

In FIG. 1, illumination light for exposure from a pulse oscillation type light source 1 such as an excimer laser illuminates a reticle 3 as pulse exposure light IL having a uniform illuminance distribution via an illumination optical system 2. The illumination optical system 2 includes a beam shaping optical system,
It consists of a dimming optical system, an optical integrator, a field stop, and a condenser lens. Reticle 3
Is formed with a semiconductor circuit pattern and a liquid crystal element pattern.
Is projected onto the wafer 10. A photoresist is applied to the surface of the wafer 10, and the projected pattern image is exposed on the resist to form a latent image.

The reticle 3 is a reticle holder 3 described later.
The reticle stage 4 is fixedly held on the reticle stage 4 via the reference numerals 0 and 32 by a sample holding device 60 described later, and moves in the XY directions in a plane perpendicular to the optical axis of the projection optical system 9.
At the time of exposure, the reticle 3 is moved in the X direction and the −X direction to scan with the exposure light IL. A movable mirror 6 is fixed on the reticle stage 4, a laser beam from a laser interferometer 7 is applied to the movable mirror 6, and the reflected beam is received by the interferometer 7 to measure the position coordinates of the reticle stage 4 in the X direction. Is done. The X-direction position coordinates are input as a signal S1 to the main control system 8 which controls the entire projection exposure apparatus. Although not shown, a movable mirror and a laser interferometer for measuring the Y direction position coordinates of the reticle stage 4 are also provided, and the Y direction position coordinates are also input to the main control system 8. The main control system 8 controls a position and a moving speed of the reticle 3 by controlling a stage driving source such as a linear motor by a reticle stage control device 4a.

Here, the sample holding device 60 for fixing the reticle 3 on the reticle stage 4 will be described in detail with reference to FIGS.

FIG. 2 showing the reticle stage 4 viewed from above.
2A, which is a front view thereof, reticle holders 30 and 32 are arranged on reticle stage 4 so as to face each other. Reticle holders 30 and 32 are formed of, for example, ceramics, and have a flatness of 0.4 μm or less. The flatness of the reticle 3 is usually 1 to 2 μm.
It is. Reticle holders 30 and 32 are formed with openings 30a and 32a for suctioning vacuum wafers along the longitudinal direction, and reticle 3 is sucked on reticle holders 30 and 32 by vacuum. Further, the reticle 3 is held and fixed between the reticle holders 30 and 32 by the sample holding device 60.

The sample holding device 60 will be described. The sample holding devices 60 are provided on the left and right, respectively.
The configuration is the same, and the sample holding device 60 on the right will be described. A pair of brackets 61 are installed at predetermined intervals outside the reticle holders 30 and 32 in the X direction. An arm 64 of a clamper 63 is rotatably supported by a shaft 62 on the pair of brackets 61. Accordingly, the clamper 63 is rotatably held with respect to the bracket 61. The height position of the axis of the shaft 62 is made to substantially coincide with the height of the surface of the reticle 3. The reason will be described later.

A driving arm 65 is provided at the center of the clamper 63.
The drive arm 65 is driven by a motor 66 with a gear head installed on the reticle stage 4. As shown in FIG. 3, a cam plate 67 is provided on the output shaft 66a of the motor 66, and a cam follower 68 is rotatably provided at one end of the cam plate 67.
The cam follower 68 comes into contact with the lower surface of the arm 65, and the motor 66 swings the cam plate 67 counterclockwise, so that the clamper 63 swings counterclockwise about the shaft 62 as the center of rotation. Arm 65 has clamper 63
Is applied by a spring (not shown) in the clockwise direction. Therefore, when the cam plate 67 is oscillated clockwise by the motor 66, the clamper 63 is oscillated clockwise by the spring force, so that the reticle is put into the reticle insertion position as shown by a two-dot chain line in FIG.

As shown in FIG. 2 (a), the pressing devices 70a, 70b, 70c
Is provided. Both have the same configuration,
This will be described with reference to FIG. 4 showing a cross section taken along the line IV-IV. Clamper 6
A cross-shaped pressing member 71 is accommodated in a columnar hole 63 a formed in 3, and a tip portion of the pressing member 71 protrudes from a lower surface of the clamper 63 by a spring force of a spring 72. The upper portion of the hole 63a is closed by a screw cover 73, and the screwing position of the screw cover 73 is adjusted to adjust the spring force by the spring 72, thereby adjusting the reticle pressing force by the pressing tool 71. The sample holding devices 60 are disposed on the left and right sides of the reticle 3, respectively, and fix both sides of the reticle 3 at three locations. At this time, the pressing force of each pressing tool 71 is individually applied to the spring 7.
Adjusted by 2. The reticle pressing force of the pressing tool 71 is determined by the moving speed (or acceleration) of the reticle stage 4.
You may decide according to. For example, when the moving speed (or acceleration) of the reticle stage 4 is high, the reticle pressing force may be increased, and when the moving speed (or acceleration) is low, the reticle pressing force may be reduced. As the material of the pressing tool 71, it is preferable to use a light material such as aluminum or plastic.

Further, each of the pressing devices 70a to 70c is provided with a limit switch (not shown) which closes when each spring 72 is bent by a predetermined amount or more. A control circuit (not shown) for stopping the rotation of the motor 66 when all the limit switches are closed is provided.

In FIG. 1, a reticle blind 5 having a rectangular opening 5a is provided on the lower surface of the reticle stage 4. Opening 5a of reticle blind 5
Thereby, a rectangular slit-shaped illumination area is substantially set on the reticle 3.

Through the projection optical system 9 disposed below the reticle blind 5, a pattern image of an illumination area limited by the opening 5a of the reticle blind 5 among the patterns drawn on the reticle 3 is formed on the wafer 10. Projected to That is, a region conjugated with respect to the projection optical system 9 and the illumination region on the reticle 3 limited by the opening 5 a of the reticle blind 5 is a rectangular exposure region on the wafer 10.

The wafer 10 is held on a Z leveling stage 12 via a wafer holder (not shown). The Z leveling stage 12 is mounted on an XY stage 13 via three actuators movable in the Z direction.
The displacement of each actuator is measured by an associated encoder. As the actuator, a method in which a cam is driven by a rotary motor to linearly move in the Z direction, a method in which a laminated piezoelectric element expands and contracts and linearly moves in the Z direction, and the like are used. An optical encoder or a capacitance encoder is used. The Z-direction displacement signal of the leveling encoder is input to the position detection device 17, and the Z-direction position, the tilt angle around the X axis, and the tilt angle around the Y axis of the wafer 10 are calculated from the measured values of the three fulcrums in the Z direction. I do. The main control system 8 controls the Z leveling actuator by the wafer stage drive circuit 16 to control the position and the tilt angle of the wafer 10 in the Z direction. If the three Z-leveling actuators are displaced by the same amount, the position in the Z-direction can be adjusted. If the three Z-leveling actuators are individually displaced, the inclination angles of the Z-leveling stage 12 around the X axis and the Y axis can be adjusted.

The XY stage 13 includes an X stage that scans the wafer 10 in the X direction and a Y stage that scans the wafer 10 in the Y direction. 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.

A movable mirror 14 for the X axis and a movable mirror (not shown) for the Y axis are fixed on the Z leveling stage 12, and a laser beam from a laser interferometer 15 fixed to the base is moved by the movable mirror 14. The reflected beam is received by the interferometer 15 and the position of the Z leveling stage 12 in the X direction is measured. The Y direction is measured similarly. The X and Y direction position coordinates are also input to the main control system 8. The main control system 8 controls a stage drive source such as a linear motor by a wafer stage drive circuit 16 to control the XY stage 13.
To control the position and moving speed of the wafer 10.

For example, when the projection optical system 9 projects an inverted image at a projection magnification β (for example, １ ／), the reticle 3 is moved via the reticle stage 4 to the illumination area in the + X direction.
Alternatively, in synchronization with scanning at the speed VR in the -X direction,
The wafer 10 is moved in the −X direction or +
Scanning is performed in the X direction at a speed VW. Here, the wafer speed V
W is represented by (1 / β) · VR.

The moving speed of the reticle stage 4 and the XY stage 13 on the wafer side during the slit scan exposure is such that the amount of the pattern exposure light IL irradiated onto the reticle 3 is applied to the opening 5a of the reticle blind 5 and the wafer 10. It is determined by the sensitivity of the photoresist and the like. That is, by the movement of the reticle stage 4, the pattern on the reticle 3 is changed to the opening 5 a of the reticle blind 5.
The stage speed is controlled so that the photoresist on the wafer 10 is sufficiently exposed to light within the time required to cross.

In FIG. 1, multipoint focus detection devices 19 and 20 are provided on both sides of the projection optical system 9 in the X direction. The multipoint focus detection devices 19 and 20
The height of the surface of the focus signal S2 is measured.
Is supplied to the arithmetic unit 18. Based on the focus signal S2 read in advance, the arithmetic unit 18 adjusts the height and inclination (the target height and the target height) to be set by the Z leveling stage 12 with respect to the exposure area to be exposed in the next exposure area. The information on the target height and the target inclination is supplied to the main control system 8. The main control system 8 controls the operation of the Z leveling stage 12 via the stage control device 16 based on this information.

In such an exposure apparatus, the reticle 3 is mechanically fixed and held on the reticle stage 4 by the sample holding device 60 provided on the reticle stage 4 and shown in FIGS. Therefore, the following operation and effect can be obtained. (1) Even if the scanning speed of the reticle stage 4 is increased by mechanically fixed holding, it is possible to reliably prevent the position from being shifted by inertial force during acceleration / deceleration as compared with the conventional vacuum suction system. Therefore, the moving speed between the reticle stage 4 and the X stage can be increased, so that the exposure time can be shortened and the throughput of the scanning type exposure apparatus can be improved. (2) In addition to the mechanical fixed holding by the clamper 63,
Since the reticle 3 is fixed even by vacuum suction similar to the conventional one, the reticle holding force can be further increased. In this case, the reticle 3 is moved by the loader to the reticle holder 3.
When the reticle 3 is mounted on the reticle 3, the reticle 3 is fixed by vacuum suction, and then the reticle 3 is fixed by the clamper 63.
This can prevent the reticle 3 from shifting when the pressing tool 71 contacts the reticle 3. That is, when the reticle 3 is placed on the reticle holders 30 and 32 by the loader, the position of the reticle 3 is rough-aligned. In that case, it is necessary to perform rough alignment again. By fixing the reticle 3 by vacuum suction in advance before mechanically fixing the reticle 3 as in the present embodiment, displacement is prevented, and re-execution of rough alignment is prevented. It is also possible to hold and fix only the clamper 63 without performing vacuum suction.

(3) Since the center of rotation of the clamper 63 is made to substantially coincide with the surface height of the reticle 3, the tip of the pressing tool 71 abuts the reticle 3 perpendicularly when the surface of the reticle 3 is pressed by the clamper 63. There is no slippage, the positioning accuracy is improved, and the possibility that dust is generated due to friction is reduced.

(4) FIGS.
As shown in FIG. 4, three pressing devices 70a to 70c are provided, and each pressing tool 71 can independently adjust its pressing force by a spring 72, and thus the reticle 3 has undulations and irregularities. Even in this case, it is possible to prevent a one-sided contact as in the case where one side of the reticle is pressed and fixed with one pressing tool as in the related art. As a result, the reticle 3 follows the plane of the reticle holders 30 and 32 having better flatness, and the flatness of the reticle 3 held is better than the flatness of the reticle 3 not held. Further, there is no possibility that an undesired load acts on the reticle 3, and no distortion is caused by the load. Furthermore, since the drive of the motor 66 is stopped when each spring 72 bends by a predetermined amount or more, if the spring constant of the spring 72 is reduced,
The pressing force of each of the pressing devices 70a to 70c can be controlled to be substantially constant.

In the above description, the reticle 3 is fixedly held by six pressing devices, but may be fixed and held by seven or more pressing devices. Although the clamper 63 is oscillated by the motor 66, it may be driven by another actuator such as an air cylinder, or the motion of the actuator may be converted into the oscillating motion of the clamper by a link instead of a cam. Alternatively, the shaft 62 may be rotationally driven by a motor to swing the clamper 63.

In the above description, the apparatus for holding the reticle 3 has been described. However, when the moving speed of the wafer is further increased, the present invention can be applied to an apparatus for fixing and holding the wafer on the Z-leveling stage. it can. further,
Although the projection exposure apparatus using an excimer laser has been described, the present invention irradiates a charged particle beam such as an electron beam onto a stencil mask or the like on which a pattern is formed, as well as a projection exposure apparatus using an x-ray. The present invention can also be applied to a charged particle beam projection exposure apparatus for projecting and exposing a pattern on a sensitive substrate by using a deflector or a deflector.

[0029]

As described above, according to the present invention, when a sample is mechanically fixedly held on a stage, the pressing force can be adjusted independently and a plurality of points on the sample can be individually adjusted. Since the pressing device for pressing is provided, the sample is reliably fixed and held even when the moving speed of the stage increases, and therefore, the effect is particularly large for the scanning exposure apparatus in which the stage moves at a high speed. In addition, the sample can be fixed and held on the stage with high accuracy without being affected by the undulation or unevenness of the sample. If vacuum suction is used together, the holding performance is further improved. If the vacuum suction is performed before the sample is held by the pressing device, there is no displacement of the sample when the sample is fixed by the pressing device.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an exposure apparatus according to an embodiment of the present invention.

FIG. 2A is a plan view of a sample holding device according to the present invention,
(B) is the front view

3A is an enlarged view of the sample holding device as viewed from the direction of line III-III, and FIG. 3B is a side view thereof.

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 2 showing the pressing device.

[Explanation of symbols]

 Reference Signs List 3 reticle 4 reticle stage 60 sample holding device 62 shaft 63 clamper 66 motor 67 cam plate 70a-70c pressing device 71 pressing device 72 spring 73 screw cap

Claims (4)

[Claims] 1. A sample holding device for holding a flat sample placed on a stage movable in at least one direction, wherein a plurality of portions of the sample can be adjusted in pressure independently. A sample holding device, comprising: a plurality of pressing devices that are individually held on a stage. 2. The sample holding device according to claim 1, wherein said stage is further provided with a vacuum suction device for vacuum suctioning said sample. 3. The sample holding device according to claim 1, wherein each of the pressing devices is provided on a clamper that is rotatably supported to hold the sample between the stage and the stage. A sample holding device, wherein a rotation axis is substantially equal to a surface height of the sample. 4. A reticle stage for fixedly holding a reticle on which a pattern is formed by a sample holding device according to claim 1, a substrate stage for holding a sensitive substrate for exposing the pattern, and a reticle. A projection optical system for projecting the transmitted illumination light onto the sensitive substrate, and projecting the pattern onto the sensitive substrate while moving the reticle stage and the substrate stage in synchronization with each other. .