JP2000164504A - Stage apparatus, exposure apparatus, and positioning method using the stage apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To make the moving range of a stage larger than the measuring range of an interferometer for measuring the position of the stage, and to measure the position of the stage with high accuracy. SOLUTION: A wafer stage WST is provided with laser interferometers 15X1, 15X2, 1 on side movable mirrors 22X, 22Y.
When moving from the position where the laser beam from 5Y is not irradiated and entering the measurement range of the laser interferometers 15X1, 15X2, and 15Y, the position of the reference mark MA is measured by the wafer alignment sensor, and based on the measurement result, To correct the measurement values of the laser interferometers 15X1, 15X2, and 15Y. Also, when the measurement stage 14 enters the measurement range of the laser interferometers 15X1, 15X2, and 15Y, the position of the reference mark MB is similarly measured by the wafer alignment sensor, and the laser interference is measured based on the measurement result. The measurement values of a total of 15X1, 15X2, and 15Y are corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stage device for positioning, for example, an object to be processed, and a lithography process provided with the stage device for manufacturing a semiconductor device, a liquid crystal display device, a thin film magnetic head, or the like. The present invention relates to an exposure apparatus used when transferring a mask pattern onto a substrate, and is particularly suitable for use in an exposure apparatus having various mechanisms such as an imaging characteristic measuring mechanism.

[0002]

2. Description of the Related Art High exposure accuracy is required for a batch exposure type (stepper type) or scanning exposure type (step-and-scan type, etc.) exposure apparatus used when manufacturing semiconductor elements and the like. . For this reason, conventionally, in an exposure apparatus, a movable mirror is fixed to a side surface of a reticle stage for mounting and positioning a reticle as a mask or a wafer stage for mounting and two-dimensionally moving a wafer as a substrate. By irradiating the movable mirror with a measurement beam from an interferometer such as a laser interferometer, the amount of movement of the stage is constantly and continuously measured, and the stage can be positioned with high accuracy based on the measured value. You can do it. In such a stage apparatus, displacement measurement with three degrees of freedom, ie, a two-dimensional movement component and a rotation component of the movable stage, is usually realized by a three-axis interferometer.

However, in such a conventional stage device, the measuring beam from each interferometer must be constantly irradiated on the movable mirror in the entire region of the maximum movement range (movable range) of the movable stage. The size of the movable mirror needs to be larger than the movable range so that the measuring beam from each interferometer can be continuously reflected even when the movable stage moves.

[0004] Therefore, in order to expand the movable range of the movable stage, a large moving mirror is required, and the shape of the entire stage must be enlarged accordingly. There arises a problem that it is difficult to move. In addition, processing a large moving mirror with a predetermined flatness involves a great deal of technical difficulty,
Further, it is technically very difficult to fix the large movable mirror to the side surface of the movable stage without causing bending. However, a decrease in the flatness of the movable mirror directly leads to a decrease in the positioning accuracy of the stage by the interferometer, so that a problem arises in that the movable range of the movable stage must be finally limited.

As a stage device for solving such a problem, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 7-253304. The disclosed stage apparatus can reduce the number of degrees of freedom of displacement of the movable stage (for example, three degrees of freedom) by installing more interferometers (for example, four axes) than one interferometer. Even if the measurement beam deviates from the measurement range of the movable mirror, the remaining interferometer can measure the degree of freedom of movement of the stage. Then, when the moving mirror re-enters the measurement range of the one interferometer deviated from the moving mirror, the measurement value of the remaining interferometer is set as the initial value of the one interferometer,
The movement amount of the movable stage can be measured by one of the interferometers, and the size of the movable mirror is made smaller than the movable range of the movable stage.

In these exposure apparatuses, it is necessary to always perform exposure with an appropriate exposure amount and with high image forming characteristics maintained. Therefore, a reticle stage for positioning a reticle or a wafer is positioned. The wafer stage is provided with a measuring device for measuring a state such as illuminance of exposure light and an imaging characteristic such as a projection magnification. For example, as a measurement device provided on a wafer stage, an irradiation amount monitor for measuring incident energy of exposure light to a projection optical system, and a spatial image detection system for measuring a position, a contrast, and the like of a projection image are provided. is there. On the other hand, as a measuring device provided on the reticle stage, for example, there is a reference plate on which an index mark used for measuring the imaging characteristics of the projection optical system is formed.

[0007]

As described above, in the conventional exposure apparatus, the exposure amount can be optimized by using the measuring apparatus provided on the reticle stage or the wafer stage, and the high imaging characteristics can be obtained. Was maintained. On the other hand, recent exposure apparatuses are also required to increase the throughput (productivity) of an exposure process when manufacturing semiconductor elements and the like. As a method for improving the throughput, in addition to the method of increasing the exposure energy per unit time, the driving speed of the stage is increased, the stepping time is reduced in the batch exposure type, and the stepping time and There is a method for reducing the scanning exposure time.

In order to improve the driving speed of the stage, when the stage system has the same size, a driving motor having a larger output may be used. To improve the speed, it is necessary to reduce the size and weight of the stage system. However, if a larger output drive motor is used as in the former case,
The amount of heat generated from the drive motor increases. Such an increased amount of heat may cause delicate thermal deformation of the stage system, so that the high positioning accuracy required by the exposure apparatus may not be obtained. Therefore, in order to prevent the deterioration of the positioning accuracy and improve the driving speed, it is desired to make the stage system as small and light as possible as in the latter case.

In particular, in a scanning exposure type exposure apparatus, the scanning exposure time is shortened by improving the driving speed, the throughput is greatly improved, and the synchronization accuracy between the reticle and the wafer is also improved by downsizing the stage system. There is a great advantage that the imaging performance and the overlay accuracy are also improved. However, when various measuring devices are provided on a reticle stage or a wafer stage as in the related art, it is difficult to reduce the size of the stage.

Further, when the reticle stage or the wafer stage is provided with a measuring device for measuring the state of the exposure light, the imaging characteristics, and the like, the measuring device usually includes a heat source such as an amplifier. At the same time, the temperature of the measuring device gradually increases due to the irradiation of exposure light during the measurement.
As a result, the reticle stage or the wafer stage may be slightly thermally deformed, and the positioning accuracy, the overlaying accuracy, and the like may be deteriorated. At present, the deterioration of the positioning accuracy etc. due to the temperature rise of the measuring device is slight, but
As circuit patterns of semiconductor elements and the like are further miniaturized, it is expected that the necessity of suppressing the influence of temperature rise of the measuring device will increase.

In this regard, the above-mentioned Japanese Patent Application Laid-Open No.
The use of the stage device disclosed in Japanese Patent Publication No. 04-2004 allows the length of the movable mirror to be smaller than the movable range of the movable stage. . Therefore, in order to improve the throughput of the exposure process and to reduce the influence of exposure light irradiation heat, further measures are required.

In an exposure apparatus, particularly a projection exposure apparatus,
Resolution, depth of focus (DOF: DeF)
pth of Forcus) and line width control accuracy.
Is also required. Here, λ is the exposure wavelength, and projection
The numerical aperture of the optical system is N. A. Then, the resolution R is λ /
N. A. And the depth of focus DOF is λ / (NA)
^Two Is proportional to Therefore, the resolution R is improved (R
Simply reduce the exposure wavelength λ
And the numerical aperture N. A. As the depth of focus DOF increases,
It gets too small.

In this regard, in order to manufacture a device, a periodic pattern such as a line and space (L / S) pattern and an isolated pattern such as a contact hole (CH) pattern have been combined. A pattern needs to be formed on the wafer. And recently,
For example, with respect to the periodic pattern,
As disclosed in Japanese Patent Application Publication No. 14, technology for improving resolution without reducing the depth of focus by a so-called modified illumination method has been developed. Also, a phase shift reticle method has been developed. Similarly, for isolated patterns, a technique has been developed to substantially improve the depth of focus and the like by, for example, controlling the coherence factor of illumination light.

Against the background of such technical trends, the double exposure method has been reviewed as a method of improving the resolution without substantially reducing the depth of focus. That is, if the double exposure method is applied, the reticle pattern for a certain layer is divided into a plurality of reticle patterns according to the type, and each is overlapped and exposed under the optimal illumination condition and exposure condition, whereby As a result, a wide depth of focus and a high resolution can be obtained. Recently, this double exposure method has been applied to a projection exposure apparatus using a KrF excimer laser and an ArF excimer laser as exposure light, for example, when the line width is 0.1 mm.
Attempts to expose device patterns, including L / S patterns down to μm, have also been considered.

However, when applying this double exposure method to a projection exposure apparatus having a single wafer stage, it is necessary to repeatedly perform steps such as alignment and exposure serially, which greatly increases throughput. There is a disadvantage of deterioration. In order to increase the throughput, a projection exposure apparatus has been proposed in which a plurality of wafer stages are provided so that alignment and exposure can be performed in parallel. However, when a plurality of wafer stages are provided in this manner, if the position of the movable stage of each wafer stage is simply measured by an interferometer, the measurement beam of the corresponding interferometer is required when each movable stage moves greatly. However, there is an inconvenience that it is difficult to quickly and reproducibly position each movable stage when each movable stage is positioned at an exposure position, for example, alternately.

In view of the above, the present invention provides a stage device having a plurality of functions, in which the movable portion is reduced in size in a state where the plurality of functions can be executed, and the movable portion can be moved at a high speed. It is a first object of the present invention to provide a stage device capable of measuring a position of a section with high accuracy while having reproducibility. Further, the present invention provides a stage device that can quickly position each of the movable portions in a reproducible state at a target position when a plurality of movable portions are provided in order to perform double exposure or the like. This is a second object.

Further, the present invention provides a reticle or a wafer provided with such a stage device while maintaining a function of measuring a characteristic when transferring a reticle pattern or an imaging characteristic of a projection optical system. It is a third object of the present invention to provide an exposure apparatus that can reduce the size of a movable portion for positioning the exposure apparatus. The invention further comprises such a stage device,
A fourth object is to provide an exposure apparatus capable of performing a double exposure method or the like at a high throughput.

Another object of the present invention is to provide a positioning method capable of quickly positioning using such a stage device.

[0019]

A first stage apparatus according to the present invention comprises a plurality of movable stages (WST, 14) arranged movably independently of each other along a predetermined moving surface.
And a first measurement system (15) that measures the position of one of the plurality of movable stages within a predetermined measurement range.
X1, 15X2, 15Y), the amount of displacement of the movable stage from a predetermined reference position within the measurement range of the plurality of movable stages, or the reference position thereof. And a second measurement system (16, 17A, 17B) for measuring the degree of coincidence with, and corrects the measurement value of the first measurement system based on the measurement result of the second measurement system.

According to the first stage apparatus of the present invention, when executing a plurality of functions such as exposure and characteristic measurement, a movable stage is assigned to each function (or each of a plurality of function groups). A plurality of movable stages (movable parts). As a result, each movable stage can be downsized, and can be driven at a high speed. However,
When a plurality of movable stages are simply provided, and a relative displacement measuring system, for example, a uniaxial laser interferometer is provided as the first measuring system, when each movable stage moves greatly, the measurement beam of the laser interferometer is interrupted. In addition, some sort of origin setting operation is required. Therefore, in the present invention, the second measurement system (16, 17A, 17) is used as a kind of absolute value measurement system.
B) was provided.

When one movable stage (WST) of the plurality of movable stages enters the measurement range from outside the measurement range of the first measurement system, the second stage (WST) becomes
A measuring system (absolute value measuring system) measures a displacement amount of the movable stage from a predetermined reference position within the measurement range, and for example, presets the displacement amount to a measurement value of the first measurement system. The measurement value of the first measurement system accurately indicates the position of the movable stage in a reproducible manner. Alternatively, when the second measurement system measures the degree of coincidence (for example, the degree of coincidence between two random patterns), when the degree of coincidence is equal to or higher than a predetermined level, the measurement value of the first measurement system is used. May be reset or preset to a predetermined value. As a result, each movable stage is positioned with high accuracy with quick reproducibility.

Next, the second stage device according to the present invention comprises a plurality of movable stages (WST1, WST2) movably arranged independently of each other along a predetermined moving surface;
A first measurement system (8) that measures the position of one movable stage among the plurality of movable stages within a predetermined first measurement range.
7Y3), wherein the position of each of the plurality of movable stages is continuously measured within a second measurement range that partially overlaps the first measurement range. Two measurement systems (87Y2, 87Y4) and a control system (38) for correcting the measurement results of the two measurement systems based on the measurement results of the first and second measurement systems are provided.

According to the second stage apparatus of the present invention, for example, a plurality of movable stages (WST1, WST2) are provided for performing double exposure. As a result, if, for example, a one-axis laser interferometer as a relative displacement measurement system is used as the first measurement system, when each movable stage is largely moved, it deviates from the measurement beam of the laser interferometer. The problem is how to position each movable stage in a reproducible manner. On the other hand, in the present invention, a single-axis (or a plurality of axes) laser interferometer is used as the first measurement system, for example, as a relative displacement measurement system. Then, when one of the plurality of movable stages enters the second measurement range from the first measurement range side, for example, the first measurement system and the second measurement system simultaneously operate the movable stage. The position of the movable stage is measured, and the value obtained by correcting the measurement value of the first measurement system in accordance with the rotation angle of the movable stage is preset to the measurement value of the second measurement system, thereby obtaining the first measurement system. Is passed to the second measurement system. After that, the movable stage can be positioned with high reproducibility using the second measurement system.

In this case, the first measurement system and the second measurement system respectively have the order (integer) N1, N2 and the phase (r
ad) φ1, φ2 (this corresponds to, for example, the phase difference between the reference signal and the measurement signal in the heterodyne interference method) and the function f (λ) of the wavelength λ of the measurement beam, and f (λ)
{N1 + φ1 / (2π)} and f (λ) {N2 + φ2 /
The position of the movable stage may be measured in the form of (2π)｝. When the position of the movable stage is measured simultaneously by the first measurement system and the second measurement system, the measurement value of the first measurement system and the movable stage Of the interference N2 'and the phase φ2' of the second measurement system from the rotation angle of the second measurement system, the second order is obtained from the order N2 ', the phase φ2' and the phase φ2 measured by the second measurement system. Order N2 of the measurement system
It is desirable to determine the preset value of. Thereafter, the measurement value of the second measurement system is expressed as f (λ) ｛N2 + φ2 / (2
By setting π)｝, the position of the movable stage can be measured with the inherent reproduction accuracy of the second measurement system even if a measurement error of the rotation angle of the movable stage occurs to some extent. Also,
The function f (λ) is, for example, λ using an integer m of 2 or more.
/ M.

Next, a first exposure apparatus according to the present invention is an exposure apparatus provided with the stage apparatus of the present invention, and the plurality of movable stages (RST1, RS1) of the stage apparatus.
A mask (R) in which different patterns are formed on T2)
, R2), and the substrate (W) is positioned while alternately positioning the mask patterns on the plurality of movable stages.
1) Transfer to the top.

According to the first exposure apparatus of the present invention,
Exposure can be performed using the double exposure method, and resolution and depth of focus can be improved. In addition, since the stage device of the present invention is provided, for example, when measuring the position of the movable stage with a laser interferometer, the movable mirror installed on the movable stage should be smaller than the movable range of the movable stage. And the weight of the movable stage can be reduced. Therefore, it is easy to move the movable stage at high speed, and the throughput can be improved.

Next, a second exposure apparatus according to the present invention is an exposure apparatus provided with the stage device of the present invention, wherein the first movable stage of the plurality of movable stages (RST, 5) of the stage device is provided. A mask (R) is mounted on the (RST), and a characteristic measuring device (6) for measuring characteristics when transferring the pattern of the mask is mounted on the second movable stage (5). The pattern of the mask (R) is transferred onto the substrate (W).

According to the second exposure apparatus of the present invention,
The first movable stage (RS) used for the original exposure
T) is provided with only the minimum functions necessary for exposure, so that the size of the first movable stage can be minimized. Therefore, the size and weight of the stage can be reduced to improve the throughput. I can do it. On the other hand, a characteristic measuring device (6) for measuring the characteristic when transferring the pattern of the mask (R) which is not directly necessary for exposure is provided by another second
Since it is mounted on the movable stage (5), it is also possible to measure characteristics when the pattern of the mask is transferred.
In addition, since the stage device of the present invention is provided, the positions of the plurality of movable stages can be measured with high accuracy.

Next, a third exposure apparatus according to the present invention is an exposure apparatus having the stage device of the present invention, and the plurality of movable stages (WST1, WST) of the stage device.
Each substrate (W1, W2) is mounted on T2), and a predetermined mask pattern is alternately exposed on the plurality of substrates while the plurality of movable stages are alternately positioned at exposure positions.

According to the third exposure apparatus of the present invention,
While one of the movable stages (WST1 and WST2) performs the exposure operation on one movable stage (WST1), the other movable stage (WST2) can carry in and carry out the substrate and perform the alignment operation. Improvement can be achieved. In addition, since the stage device of the present invention is provided, the positions of the plurality of movable stages can be measured with high accuracy.

Next, a fourth exposure apparatus according to the present invention is an exposure apparatus including the stage apparatus of the present invention and a projection optical system (PL), and the plurality of movable stages (WST) of the stage apparatus. , 14) of the first movable stage (WS
T), the substrate (W) is placed on the second movable stage (1).
4) A characteristic measuring device (20) for measuring an imaging characteristic of the projection optical system is mounted on the apparatus, and a predetermined mask pattern is formed on the substrate on the first movable stage through the projection optical system. Exposure.

According to the fourth exposure apparatus of the present invention,
The first movable stage (WS) used for the original exposure
By giving T) only the minimum functions necessary for exposure, the first movable stage (WST) can be reduced in size and weight to improve throughput. On the other hand, since the characteristic measuring device (20) for measuring the imaging characteristics of the projection optical system which is not directly required for exposure is mounted on another second movable stage (14), the imaging characteristics are also reduced. Can be measured. In addition, since the stage device of the present invention is provided, the positions of the plurality of movable stages can be measured with high accuracy.

Next, a first positioning method according to the present invention is a positioning method using the stage device of the present invention, wherein one of the plurality of movable stages (WST, 14) is a movable stage (WST). When the movable stage enters the measurement range of the first measurement system, the amount of displacement of the movable stage from a predetermined reference position within the measurement range or the degree of coincidence with the reference position is measured by the second measurement system. Then, the measurement value of the first measurement system is corrected based on the measurement result. According to such a positioning method, the plurality of movable stages can be positioned with high accuracy in a state in which each of the movable stages has reproducibility easily.

Next, a second positioning method according to the present invention is a positioning method using the stage device of the present invention, wherein one of the plurality of movable stages (WST1, WST2) is the second movable stage. When entering the first measurement range from the second measurement range side, the position of the movable stage is simultaneously measured by the first and second measurement systems, and the measurement of the first measurement system is performed based on the measurement result. The result is matched with the measurement result of the second measurement system. According to such a positioning method, the plurality of movable stages can be positioned with high accuracy in a state in which each of the movable stages has reproducibility easily.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the present invention is applied to a step-and-scan projection exposure apparatus. FIG. 1 shows a projection exposure apparatus of the present embodiment,
In FIG. 1, at the time of exposure, light was emitted from an illumination system 1 including an exposure light source, a beam shaping optical system, a fly-eye lens for uniforming the illuminance distribution, a light amount monitor, a variable aperture stop, a field stop, a relay lens system, and the like. The exposure light IL illuminates a slit-shaped illumination area on the pattern surface (lower surface) of the reticle R via the mirror 2 and the condenser lens 3. As the exposure light IL, excimer laser light such as KrF (wavelength 248 nm) or ArF (wavelength 193 nm), Y
Higher harmonics of AG laser or i-line of mercury lamp (wavelength 36
5 nm) can be used. By switching the variable aperture stop in the illumination system 1, the normal illumination method, the annular illumination,
It is configured such that a desired illumination method can be selected from so-called modified illumination and illumination with a small coherence factor (σ value). When the exposure light source is a laser light source, the light emission timing and the like are controlled via a laser power supply (not shown) by a main control system 10 that controls the overall operation of the apparatus.

The image of the pattern of the reticle R in the illumination area 9 (see FIG. 3) by the exposure light IL is projected onto the projection optical system PL.
Is reduced at a projection magnification β (β is １ ／ times, １ ／ times or the like), and is projected onto a slit-shaped exposure region 12 on a wafer W coated with a photoresist. . Hereinafter, the Z axis is taken in parallel with the optical axis AX of the projection optical system PL, and a non-scanning direction orthogonal to the scanning direction of the reticle R and the wafer W at the time of scanning exposure (that is, FIG.
The X axis is taken along the direction perpendicular to the plane of FIG. 1, and the Y axis is taken along the scanning direction (that is, the direction parallel to the plane of FIG. 1).

First, reticle R is mounted on reticle stage R
The reticle stage RST is held on the ST by vacuum suction, and has two guides 4A and 4B arranged in parallel.
It is movably mounted in the Y-direction via an air bearing. Further, in this example, on the guides 4A and 4B,
The measurement stage 5 is mounted movably in the Y direction via an air bearing independently of the reticle stage RST.

FIG. 3 is a plan view showing the reticle stage RST and the measurement stage 5. In FIG.
A reticle stage RST and a measurement stage 5 are mounted along guides 4A and 4B extending in the Y direction (scanning direction) so as to be driven in the Y direction by a linear motor or the like (not shown). The length of the guides 4A and 4B is set to be longer than the moving stroke of the reticle stage RST at the time of scanning exposure by at least the width of the measurement stage 5. The reticle stage RST is
It is configured by combining a coarse movement stage that moves in the Y direction and a fine movement stage whose two-dimensional position can be finely adjusted on the coarse movement stage. Further, on the reticle mark stage RST, a pair of reference mark plates 17C1 and 17C2 is fixed in such a manner that the reticle R is sandwiched in the X direction. Reference marks MC1 and MC2 are formed. The positional relationship between the reference marks MC1 and MC2 and the original pattern of the reticle R is measured with high precision in advance and stored in the storage unit of the main control system 10.

A reference plate 6 made of a glass plate elongated in the X direction is fixed on the measurement stage 5, and a plurality of index marks IM for measuring the imaging characteristics of the projection optical system PL are arranged on the reference plate 6 in a predetermined manner. It is formed with. The reference plate 6 is large enough to cover the slit-shaped illumination area 9 of the exposure light for the reticle R, more precisely, the width in the X direction of the field of view of the projection optical system PL on the reticle R side. By using the reference plate 6, there is no need to prepare a dedicated reticle for measuring the imaging characteristics, and it is not necessary to replace the reticle R for actual exposure with the dedicated reticle.
The imaging characteristics can be measured with high frequency, and it is possible to accurately follow the temporal change of the projection optical system PL. The measurement stage 5 is also provided with a positioning mechanism in a minute range in the X direction (non-measurement direction), and a pair of reference plates 6 is placed on the measurement stage 5 so as to sandwich the reference plate 6 in the X direction. The reference mark plates 17D1 and 17D2 are fixed, and the reference mark plates 17D1 and 17D2 are fixed.
Two-dimensional, for example, cross-shaped reference marks MD1 and MD2 are formed on D1 and 17D2, respectively. Fiducial mark M
The positional relationship between D1 and MD2 and the plurality of index marks IM is also accurately measured in advance and stored in the storage unit of the main control system 10.

As described above, in this embodiment, the measurement stage 5 for the reference plate 6 is provided independently, and no measurement member other than the reticle R is mounted on the original reticle stage RST. That is, the reticle stage RST needs to have only the minimum scanning and positioning functions required for scanning exposure, so that the size of the reticle stage RST can be reduced.
Lighter weight has been realized. Therefore, reticle stage R
Since the ST can be scanned at higher speed, the throughput of the exposure process is improved. In particular, in the case of reduced projection, the scanning speed of the reticle stage RST is 1 / β times (for example, 4 times, 5 times, or the like) the scanning speed of the wafer stage, so the upper limit of the scanning speed is almost determined by the reticle stage. In this case, in this case, in this example, the throughput is particularly greatly improved.

A reticle stage R is provided by a laser interferometer 7Y installed in the + Y direction with respect to the guides 4A and 4B.
The movable mirror 24Y on the side surface in the + Y direction of ST is irradiated with a laser beam, and a two-axis laser interferometer 7 installed in the + X direction.
A laser beam is emitted from X1, 7X2 to the movable mirror 24X on the side in the + X direction of the reticle stage RST, and the X, Y, and rotation angles of the reticle stage RST are measured and measured by the laser interferometers 7Y, 7X1, 7X2. The values are supplied to the main control system 10 shown in FIG. 1, and the main control system 10 controls the speed and position of the reticle stage RST via a linear motor or the like based on the measured values. Guide 4
Laser interferometer 8 installed in -Y direction with respect to A and 4B
Moving mirror 25 on the side in −Y direction of measurement stage 5 from Y
Y is irradiated with a laser beam, and the Y coordinate of the measurement stage 5 measured by the laser interferometer 8Y is determined by the main control system 10.
Supplied to The optical axes of the Y-axis laser interferometers 7Y and 8Y pass through the center of the illumination area 9, that is, the optical axis AX of the projection optical system PL along the Y direction, and the laser interferometers 7Y and 8Y respectively Constant reticle stage R
The ST and the position of the measurement stage 5 in the scanning direction are measured.

The orthogonal side surfaces of the reticle stage RST are mirror-finished, and these mirror surfaces are
X and 24Y may be regarded as mirror surfaces of the measuring stage 5 which are orthogonal to each other, and these mirror surfaces are
It may be regarded as 5X, 25Y. Further, in the present embodiment, as shown in FIG. 1, the amount of misalignment between the alignment mark (reticle mark) formed on the reticle R and the corresponding reference mark (not shown) on the wafer stage above the reticle R. Are provided with a pair of reticle alignment microscopes RA and RB for detecting. Straight lines passing through the detection centers of the reticle alignment microscopes RA and RB are parallel to the X axis, and the centers of the detection centers coincide with the optical axis AX. In this example, reticle alignment microscopes RA and RB corresponding to the second measurement system (absolute value measurement system) of the present invention
Are used to detect the positions of the reference marks MC1 and MC2 on the reticle stage RST and the reference marks MD1 and MD2 on the measurement stage 5 shown in FIG.

When measuring the imaging characteristics, the reticle stage RST is retracted in the + Y direction, and the measurement stage 5 is moved in the Y direction so that the reference plate 6 almost covers the illumination area 9, and the laser interferometer 7X1 , 7X2 deviate from the side surface of reticle stage RST and irradiate movable mirror 25X of measurement stage 5 in the + X direction. At this time, the reticle alignment microscope RA,
The amount of displacement from the detection center (center of the visual field) of the reference marks MD1 and MD2 on the reference plate 6 is detected by RB, and the main control system 10 in FIG.
Of the measuring stage 5 such that the centers of the measurement stages 5
Position. Then, in this state, the measurement values of the X-axis laser interferometers 7X1 and 7X2 are reset.
The measured values may be preset to, for example, a predetermined value.

Thereafter, the position of the measurement stage 5 in the X direction and the rotation angle are measured with high reproducibility by the laser interferometers 7X1 and 7X2, and the position of the measurement stage 5 in the Y direction is determined. It is always measured with high precision by the laser interferometer 8Y. Therefore, based on these measured values, the main control system 10 can control the position of the measuring stage 5 with high accuracy via a linear motor or the like. In addition,
Instead of minimizing the amount of misalignment of the reference marks MD1 and MD2 as described above,
The measurement values of the laser interferometers 7X1 and 7X2 may be preset to corresponding values.

On the other hand, during measurement, reticle stage RS
Although the position of T in the non-scanning direction is not measured, when the reticle stage RST reaches below the illumination area 9 for exposure, the laser beams from the laser interferometers 7X1 and 7X2 are again irradiated on the moving mirror 24X of the reticle stage RST. Become so. Then, similarly to the case of the measurement stage 5, the reticle alignment microscopes RA and RB detect the positional deviation amounts of the reference marks MC1 and MC2 on the reticle stage RST, and the main control system 10 detects the positional deviation amounts. The reticle stage R so that
With the ST positioned, the laser interferometers 7X1, 7X
2 is preset to a predetermined value. Thereafter, the position in the X direction and the rotation angle of the reticle stage RST are measured in a reproducible state, and the position in the Y direction is constantly measured by the laser interferometer 7Y. It can be positioned at a desired position with high accuracy. Therefore, there is no disadvantage that the laser beams from the laser interferometers 7X1 and 7X2 are interrupted.

Returning to FIG. 1, wafer W is held on wafer stage WST via a wafer holder (not shown), and wafer stage WST is mounted on surface plate 13 movably in the X and Y directions via an air bearing. Is placed. The wafer stage WST also incorporates a focus / leveling mechanism for controlling the position (focus position) of the wafer W in the Z direction and the tilt angle. Further, a measurement stage 14 provided with various measuring devices movably in the X and Y directions via an air bearing separately from the wafer stage WST is mounted on the surface plate 13. The mechanism for controlling the focus position on the upper surface of the measurement stage 14 is also incorporated.

FIG. 2 is a plan view showing the wafer stage WST and the measurement stage 14. In FIG. 2, for example, a coil array is buried in the surface of the surface plate 13 in a predetermined arrangement. On the bottom surface of the WST and the bottom surface of the measurement stage 14, a magnet row is embedded together with a yoke, and the coil row and the corresponding magnet row constitute a planar motor, respectively. The position of the stage 14 in the X and Y directions and the rotation angle are controlled independently of each other. The plane motor is disclosed in more detail in, for example, Japanese Patent Application Laid-Open No. 8-51756.

The wafer stage WST of this embodiment has only the minimum functions required for exposure. That is, wafer stage WST includes a focus / leveling machine, and a wafer holder (bottom side of wafer W) for holding wafer W by suction and reference mark MA for position measurement of wafer stage WST are provided on wafer stage WST. The formed reference mark plate 17A is provided. A reticle alignment reference mark (not shown) is also formed on the reference mark plate 17A.

As shown in FIG. 1, an off-axis image processing type wafer alignment sensor 16 for alignment of the wafer W is provided adjacent to the projection optical system PL. The detection signal is supplied to an alignment processing system in the main control system 10. The wafer alignment sensor 16 is a sensor for measuring the position of an alignment mark (wafer mark) attached to each shot area on the wafer W. In this example,
Using wafer alignment sensor 16, the position of reference mark MA or the like on wafer stage WST is detected. That is, the wafer alignment sensor 16 corresponds to the second measurement system (absolute value measurement system) of the present invention.

The surface of measurement stage 14 is set at substantially the same height as the surface of wafer W on wafer stage WST. In FIG. 2, on the measurement stage 14, an irradiation amount monitor 18 including a photoelectric sensor for measuring the energy per unit time (incident energy) of the exposure light that has passed through the projection optical system PL, and the projection optics A nonuniform illuminance sensor 19 composed of a photoelectric sensor for measuring an illuminance distribution in a slit-shaped exposure area 12 by the system PL, a measurement plate 20 formed with slits 21X and 21Y for measuring imaging characteristics, and a position reference. Reference mark M
The reference mark plate 17B on which B is formed is fixed.
The positional relationship between the reference mark MB and the uneven illuminance sensor 19 and the like is measured with high precision in advance and stored in the storage unit of the main control system 10 in FIG. The position of the reference mark MB is also measured by the wafer alignment sensor 16.

A condensing lens and a photoelectric sensor are arranged on the bottom side of the X-axis slit 21X and the Y-axis slit 21Y of the measuring plate 20, respectively. It is configured. Note that, instead of the slits 21X and 21Y, edges of a rectangular opening may be used. The light receiving surface of the irradiation amount monitor 18 is formed to have a size that covers the exposure region 12,
The light receiving portion of the uneven illuminance sensor 19 has a pinhole shape, and detection signals from the irradiation amount monitor 18 and the uneven illuminance sensor 19 are supplied to the main control system 10 in FIG.

The detection signal of the photoelectric sensor at the bottom of the measurement plate 20 is supplied to the imaging characteristic calculation system 11 shown in FIG.
In this case, when measuring the imaging characteristics of the projection optical system PL, the reference plate 6 on the measurement stage 5 on the reticle side in FIG. The image is projected on the wafer stage side, and the image is scanned by slits 21X and 21Y on the measurement plate 20 in the X and Y directions, respectively, and the detection signal from the bottom photoelectric sensor is captured by the imaging characteristic calculation system 11. . The imaging characteristic calculation system 11 processes the detection signal to obtain the index mark IM.
The image position, contrast, and the like of the image are detected, and the imaging characteristics such as the curvature of field, distortion, and the best focus position of the projected image are obtained from the detection result and output to the main control system 10. Further, although not shown, a mechanism for driving a predetermined lens in the projection optical system PL to correct an image forming characteristic such as a predetermined distortion is also provided, and the main control system 10 transmits the correction signal via the correction mechanism. The projection optical system PL is configured to be able to correct the imaging characteristics.

In FIG. 2, sensors such as an irradiation amount monitor 18, an illuminance unevenness sensor 19, and a photoelectric sensor at the bottom of the measurement plate 20 provided on the measurement stage 14 are all provided with a heat source such as an amplifier. Power supply and signal cable for communication are connected. Therefore, if those sensors are mounted on the wafer stage WST for exposure, there is a possibility that the positioning accuracy and the like may be degraded by the heat source and the tension of the signal cable attached to the sensors. In addition, thermal energy due to exposure light exposure during measurement of imaging characteristics and the like may cause deterioration of positioning accuracy and the like. On the other hand, in the present example, these sensors are provided on the measurement stage 14 separated from the exposure wafer stage WST, so that the wafer stage WST can be reduced in size and weight, and the measurement sensor 14 There is an advantage that a decrease in positioning accuracy due to a heat source or thermal energy of exposure light during measurement can be prevented. Further, by reducing the size of the wafer stage WST, the wafer stage WS
The moving speed and controllability of T are improved, the throughput of the exposure process is increased, and the positioning accuracy and the like are further improved.

Further, the laser interferometer 15Y installed in the + Y direction with respect to the
The movable mirror 22Y on the side surface in the Y direction is irradiated with a laser beam, and a two-axis laser interferometer 15X installed in the −X direction
The moving mirror 22X on the side surface of the wafer stage WST in the −X direction is irradiated with a laser beam from the laser stage 1, 15X2, and the X, Y, and rotation angles of the wafer stage WST are measured by the laser interferometers 15Y, 15X1, and 15X2. The measured values are supplied to main control system 10 in FIG. 1, and main control system 10 controls the speed and position of wafer stage WST via a planar motor based on the measured values. Similarly, an X-axis movable mirror 23X and a Y-axis movable mirror 23Y are also attached to the side surface of the measurement stage 14. Note that the orthogonal side surfaces of wafer stage WST may be mirror-finished and these mirror surfaces may be regarded as movable mirrors 22X and 22Y, and similarly, the mirror surfaces on the side surfaces of measurement stage 14 may be regarded as movable mirrors 23X and 23Y. Good.

When measuring the incident energy of the exposure light and the like, the position measuring laser beams are applied to the moving mirrors 23X and 23Y of the measuring stage 14. FIG.
Shows an example of the arrangement of the wafer stage WST and the measurement stage 14 at the time of measuring the incident energy of the exposure light and the like. In this manner, the wafer stage WST is retracted to a position away from the exposure region 12 and When the measurement stage 14 is moved so that the laser interferometer 15
The laser beams from X1, 15X2, and 15Y deviate from moving mirrors 22X and 22Y of wafer stage WST, and are irradiated on moving mirrors 23X and 23Y of measurement stage 14. At this time, the measurement stage 14 is moved so that the reference mark MB on the measurement stage 14 falls within the field of view 16a of the wafer alignment sensor 16 in FIG. 1, and the two-axis X-axis laser interferometer 15X1 , 15X2
Measurement stage 14 so that the measured values of
While the rotation angle is controlled, the amount of displacement from the detection center of the reference mark MB is detected. And the main control system 10
Calculates the X component and the Y component of the displacement amount by the laser interferometers 15X1, 15X2 and 15X2, respectively.
Preset to Y measurement value. After that, the position of the measurement stage 14 is measured with high accuracy by the laser interferometers 15X1, 15X2, and 15Y in a reproducible state. The position of the stage 14 can be controlled with high accuracy.

On the other hand, at the time of exposure, as shown in FIG.
Laser interferometers 15X1, 15X
The reference marks MA are moved into the field of view 16a of the wafer alignment sensor 16 by irradiating the laser beams from X2 and 15Y, and the laser interferometers 15X1 and 15X are moved.
In the state where the measured values of X2 are matched, the amount of displacement of the reference mark MA is measured, and the measured values of the laser interferometers 15X1, 15X2, and 15Y are preset based on the measured values. Thereafter, positioning of wafer stage WST is performed with high accuracy in a state having reproducibility. In addition, since the position of wafer stage WST and measurement stage 14 can be roughly controlled by driving the planar motor in an open loop, main control system 10 controls wafer stage WST, The position of the measurement stage 14 is driven by an open loop system using a planar motor.

Returning to FIG. 1, an oblique incidence type focus position detection system (AF sensor) for measuring a focus position on the surface of the wafer W is arranged on a side surface of the projection optical system PL, although not shown. Based on the detection result, the surface of the wafer W during the scanning exposure is focused on the image plane of the projection optical system PL. Next, the operation of the projection exposure apparatus of this embodiment will be described.
First, the incident light amount of the exposure light IL to the projection optical system PL is measured using the measurement stage 14 on the wafer stage side. In this case, in order to measure the amount of incident light with the reticle R loaded, in FIG. 1, a reticle R for exposure is loaded on a reticle stage RST, and the reticle R moves on the illumination area of the exposure light IL. I do. Thereafter, as shown in FIG. 4, wafer stage WST is retracted on surface plate 13 in, for example, the + Y direction, and measurement stage 14 moves toward exposure area 12 by projection optical system PL. Then, as described above, the laser interferometers 15X1, 15X2, 1
After presetting the measurement value of 5Y, the measurement stage 14 stops at a position where the light receiving surface of the irradiation amount monitor 18 on the measurement stage 14 covers the exposure region 12, and in this state, the measurement stage 14 passes through the irradiation amount monitor 18. The light amount of the exposure light IL is measured.

The main control system 10 supplies the measured light quantity to the imaging characteristic calculation system 11. At this time, for example, a measurement value obtained by detecting a light beam obtained by branching from the exposure light IL in the illumination system 1 is also supplied to the imaging characteristic calculation system 11. The projection optical system PL is calculated from the amount of light monitored in the illumination system 1 based on the two measurement values.
Is calculated and stored for indirectly calculating the amount of light incident on. During this time, wafer W is loaded on wafer stage WST. Thereafter, as shown in FIG. 2, measurement stage 14 is retracted to a position away from exposure area 12, and wafer stage WST moves toward exposure area 12. When wafer stage WST is retracted, as shown in FIG. 4, laser interferometers 15Y and 15X
Because the laser beam from 1,15X2 is not irradiated,
For example, position control is performed by driving a planar motor in an open loop manner.

Then, the measurement stage 14 is moved to the exposure region 1
2 and retract the wafer stage WST to the exposure region 1
2, and after presetting the measurement values of the laser interferometers 15Y, 15X1, 15X2 as described above, the reference mark member 1 on the wafer stage WST is set.
The center of the reticle reference mark (not shown) on 7A is
Wafer stage WST is moved so as to be located near optical axis AX (the center of exposure area 12). Thereafter, using the reticle alignment microscopes RA and RB, the reticle shown in FIG. By driving the stage RST, alignment of the reticle R is performed. At about the same time, the position of another reference mark MA on the reference mark plate 17A is detected again by the wafer alignment sensor 16 in FIG. 1 so that the distance between the detection center of the sensor and the center of the projected image of the reticle R is obtained. (Baseline amount) is accurately detected.

Next, by detecting the position of a wafer mark attached to a predetermined shot area (sample shot) on the wafer W via the wafer alignment sensor 16, the arrangement coordinates of each shot area of the wafer W are obtained. Can be Thereafter, scanning exposure is performed while aligning the exposure target shot area of the wafer W with the pattern image of the reticle R based on the arrangement coordinates and the above-described baseline amount. At the time of scanning exposure to each shot area on the wafer W, in FIG.
3 (see FIG. 3), the reticle R is scanned at a speed VR in the + Y direction (or -Y direction) via the reticle stage RST, and is synchronized with the exposure region 12 via the wafer stage WST. The wafer W is in the −X direction (or + X
Direction) at a speed β · VR (β is a projection magnification).

Also, during the exposure, for example, the light amount of the light beam branched from the exposure light IL in the illumination system 1 is constantly measured and supplied to the imaging characteristic calculation system 11.
The amount of the exposure light IL incident on the projection optical system PL is calculated based on the measured value of the supplied light amount and a coefficient obtained in advance, and the projection optical system P generated by absorption of the exposure light IL is calculated.
The amount of change in the imaging characteristics (projection magnification, distortion, etc.) of L is calculated, and the calculation result is supplied to the main control system 10.
The main control system 10 corrects the image forming characteristics by, for example, driving a predetermined lens in the projection optical system PL.

The normal exposure has been described above. However, when measuring the state of the projection exposure apparatus of this embodiment for maintenance or the like, the measurement stage 14 is moved to the exposure area 12 to perform the measurement. For example, when measuring the illuminance uniformity in the exposure area 12, after removing the reticle R from the reticle stage RST, the illuminance unevenness sensor 19 is finely moved in the X direction and the Y direction in the exposure area 12 in FIG. Measure the illuminance distribution.

Next, the operation of measuring the image formation measurement of the projection optical system PL using the measurement stage 5 on the reticle stage side and the measurement stage 14 on the wafer stage side will be described. In this case, in FIG. 3, reticle stage RST is retracted in the + Y direction, and reference plate 6 on measurement stage 5 moves into illumination area 9. At this time, the laser interferometers 7X1 and 7X2 in the non-scanning direction are
, And the measurement values are reset (or preset) as described above using the reticle alignment microscopes RA and RB. Thereafter, the measuring stage 5 is positioned with high accuracy based on the measured values of the laser interferometers 7X1, 7X2, 8Y.

At this time, as described above, the images of the plurality of index marks IM are projected on the wafer stage side via the projection optical system PL. In this state, in FIG.
The measurement stage 14 is driven to scan the image of the index mark IM in the X direction and the Y direction with the slit on the measurement plate 20, and the detection signal of the photoelectric sensor at the bottom of the measurement plate 20 is used as the imaging characteristic calculation system 11. , The position and the contrast of those images are obtained. Also, the measuring plate 20
While changing the focus position by a predetermined amount, the position and contrast of those images are obtained. From these measurement results, the imaging characteristic calculation system 11 obtains the fluctuation amount of the imaging characteristics such as the best focus position, the field curvature, and the distortion (including the magnification error) of the projected image of the projection optical system PL. This fluctuation amount is supplied to the main control system 10, and when the fluctuation amount exceeds the allowable range, the main control system 10 corrects the imaging characteristics of the projection optical system PL.

As described above, in the projection exposure apparatus of this embodiment,
Reference mark M by wafer alignment sensor 16
The positions of the wafer stage WST or the measurement stage 14 are detected by the laser interferometers 15X1, 15X2, and 15Y in order to detect the positions of A and MB and preset the laser interferometers 15X1, 15X2, and 15Y based on the position information. Can be measured and controlled with high reproducibility and high accuracy. Similarly, reticle alignment microscopes RA and RB
By detecting the positions of the reference marks MC1, MC2 or MD1, MD2 and resetting the laser interferometers 7X1, 7X2, etc., the position of the reticle stage RST or the measurement stage 5 can be detected with high reproducibility and high accuracy. It can be measured and controlled.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the present invention is applied to a step-and-scan projection exposure apparatus that performs exposure by a double exposure method. FIG. 5 shows a schematic configuration of the projection exposure apparatus of the present example.
The projection exposure apparatus of the present example is a stage apparatus including a plurality of movable stages WST1 and WST2 as a plurality of movable stages that independently hold two wafers W1 and W2 as sensitive substrates and move two-dimensionally. A projection optical system PL1 disposed above the stage device, a reticle driving mechanism for driving a reticle R1 or R2 (see FIG. 6) as a mask above the projection optical system PL1 in a predetermined scanning direction, and reticles R1 and R2. And a control system for controlling these components.
Hereinafter, the Z axis is taken in parallel with the optical axis AX1 of the projection optical system PL1, and the X axis is taken in a plane perpendicular to the Z axis in parallel with the plane of FIG.
The description will be made by taking the Y axis perpendicular to the plane of FIG. In this example,
The direction parallel to the Y axis (Y direction) is the scanning direction.

First, the stage device is floated and supported on a base board 86 via an air bearing (not shown), and is movable independently in the X and Y directions.
T1, WST2 and these wafer stages WST1,
A wafer stage drive system 81W that drives WST2 and an interferometer system that measures the positions of wafer stages WST1 and WST2 are provided.

More specifically, an air pad (not shown) (for example, a vacuum preload type air bearing) is provided at a plurality of locations on the bottom surface of wafer stages WST1 and WST2. In a state where, for example, an interval of several μm is maintained by balance with pressure,
Wafer stages WST1 and WST2 are levitated and supported on base plate 86.

FIG. 7 shows wafer stages WST1 and WST.
2 is shown in FIG. 7, and in FIG.
On the top are two X-axis linear guides 95 extending in the X direction.
A and 95B are provided in parallel. A pair of permanent magnets for a linear motor are fixed along the X-axis linear guides 95A and 95B, respectively, and two movable members 93A, 93C and Two moving members 93B, 9
3D is attached. These four moving members 93
Drive coils (not shown) are attached to the bottom portions of A to 93D so as to surround the X-axis linear guide 95A or 95B from above and from the side, respectively. These drive coils and the X-axis linear guide 95A or 95B Accordingly, a moving coil type linear motor that drives each of the moving members 93A to 93D in the X direction is configured. Therefore, in the following description, for convenience, these moving members 93A
To 93D are referred to as “X-axis linear motors”.

Of these, two X-axis linear motors 93A, 93
3B are provided at both ends of a Y-axis linear guide 94A extending in the Y direction, and the remaining two X-axis linear motors 93C and 93 are provided.
D is also fixed to both ends of a Y-axis linear guide 94B extending in the Y direction. A set of drive coils for a linear motor is fixed to each of the Y-axis linear guides 94A and 94B along the Y direction. Therefore, the Y-axis linear guide 94
A is driven in the X direction along X-axis linear guides 95A and 95B by X-axis linear motors 93A and 93B.
The Y-axis linear guide 94B includes an X-axis linear motor 93C,
Driven in the X direction along the X-axis linear guides 95A and 95B by 93D.

On the other hand, a set of permanent magnets (not shown) surrounding one Y-axis linear guide 94A from above and from the side is provided at the bottom of wafer stage WST1, and this permanent magnet and Y-axis linear guide 94A are provided. Thus, a moving magnet type linear motor that drives wafer stage WST1 in the Y direction is configured. Similarly, a moving magnet type linear motor that drives wafer stage WST2 in the Y direction is constituted by a set of permanent magnets (not shown) provided at the bottom of wafer stage WST2 and Y-axis linear guide 94B.

That is, in this example, the X-axis linear guides 95A and 95B, the X-axis linear motors 93A to 93D,
Y-axis linear guides 94A and 94B and wafer stage W
The wafer stages WST1 and WST2 are independently XY controlled by a permanent magnet (not shown) at the bottom of ST1 and WST2.
A stage system driven two-dimensionally on a plane is configured.
These wafer stages WST1 and WST2 are controlled by stage control device 38 via stage drive system 81W in FIG. The operation of the stage control device 38 is controlled by the main control device 90.

The balance between the thrust of the pair of X-axis linear motors 93A and 93B provided at both ends of the Y-axis linear guide 94A is slightly changed, so that the wafer stage W
It is also possible to generate or remove minute yawing in ST1. Similarly, a pair of X-axis linear motors 93
By slightly changing the thrust balance between C and 93D,
Micro yawing can be generated or removed from wafer stage WST2. Wafers W1 and W2 are fixed on these wafer stages WST1 and WST2 via a wafer holder (not shown) by vacuum suction or the like, respectively. The wafer holder is minutely driven in a Z direction and a θ direction (a rotation direction around the Z axis) by a Z · θ driving mechanism (not shown).

Further, the side surfaces of wafer stage WST1 in the −X direction and the + Y direction are mirror-finished reflecting surfaces 8.
4X, 84Y (see FIG. 6). Similarly, the side surfaces of the wafer stage WST2 in the + X direction and the + Y direction are:
The mirror surfaces are reflection surfaces 85X and 85Y. These reflecting surfaces correspond to moving mirrors, and measurement beams 92X2 composed of laser beams from respective laser interferometers constituting an interferometer system described later are provided on these reflecting surfaces.
92X5, 92Y1 to 92Y are projected, and the reflected light is received by each laser interferometer, so that a reference mirror is disposed on a reference surface of each reflecting surface (generally, a reference mirror is arranged on the side of the projection optical system or the side of the alignment optical system, and Is set as a reference plane), whereby the wafer stage WST1,
The two-dimensional position of WST2 is measured. The configuration of the interferometer system will be described later in detail.

In FIG. 5, as the projection optical system PL1, a refraction optical system composed of a plurality of lens elements having a common optical axis in the Z direction and having a predetermined reduction magnification, for example, 1/5, both-side telecentric is used. Have been. Note that a catadioptric system or a reflective system may be used as the projection optical system PL1. On both sides of the projection optical system PL1 in the X direction, as shown in FIG. 5, an off-axis type alignment system 88 having the same function as each other.
A and 88B are located at the same distance from the optical axis AX1 (coincident with the center of the projected image of the reticle pattern) of the projection optical system PL1. These alignment systems 88A and 88B are an LSA (Laser Step Alignment) system using a slit-like laser beam, an image processing FIA (Field Image Alignment) system, for example, an LIA that detects diffracted light of two heterodyne beams.
It has three types of (Laser Interferometric Alignment) type alignment sensors, and can measure the position of the reference mark on the reference mark plate and the alignment mark on the wafer in two-dimensional directions (X direction and Y direction).
In this example, these three types of alignment sensors are properly used according to the purpose, so-called search alignment for detecting the positions of three one-dimensional marks on the wafer and measuring the approximate position of the wafer, and various types of alignment sensors on the wafer. Fine alignment and the like for accurate measurement of the position of the shot area are performed.

In this case, one alignment system 88A
Is a wafer W1 held on wafer stage WST1.
It is used for measuring the position of the upper alignment mark. The other alignment system 88B is connected to the wafer stage W
It is used for position measurement of an alignment mark on the wafer W2 held on ST2. The detection signals from the respective alignment sensors constituting these alignment systems 88A and 88B are supplied to an alignment control device 80, and the alignment control device 80 converts the supplied detection signals into A / A signals.
D (analog / digital) conversion and digitized waveform signals are arithmetically processed to detect mark positions. The detection result is sent to the main controller 90, and the main controller 90 outputs the position correction information at the time of exposure to the stage controller 38 in accordance with the detection result.

Although not shown, the projection optical system PL
1 and alignment systems 88A and 88B each have an auto-focus / auto-leveling measurement mechanism (hereinafter referred to as “AF / AF”) for detecting the defocus amount from the best focus position on the exposure surface of the wafer W1 (or W2).
AL system). Among them, a so-called oblique incidence type multipoint AF system is used as the AF / AL system of the projection optical system PL1. A similar AF / AL system is provided for the alignment systems 88A and 88B. That is, in this example, the AF / AL used in the alignment sequence is used for the measurement area substantially the same as the AF / AL system used for detecting the defocus amount at the time of exposure.
It is configured so that the detection beam can be irradiated depending on the system. For this reason, even during the alignment sequence using the alignment systems 88A and 88B, the position of the alignment mark can be measured with high accuracy with the same focusing accuracy as that at the time of exposure. In other words, an offset (error) due to the posture of the stage does not occur between the time of exposure and the time of alignment.

Next, the reticle driving mechanism will be described with reference to FIGS. This reticle drive mechanism
XY while holding reticle R1 on reticle base board 79
Reticle stage RST that can move in two-dimensional directions on a plane
1, a reticle stage RST2 capable of holding a reticle R2 along the same moving surface and moving in a two-dimensional direction, a linear motor (not shown) for driving these reticle stages RST1 and RST2, and a reticle stage RS
A reticle interferometer system for managing the positions of T1 and RST2.

More specifically, as shown in FIG. 6, these reticle stages RST1 and RST2 are arranged in series in the scanning direction (Y direction), and the reticle base RST is connected to a reticle base via an air bearing (not shown). The reticle stage drive mechanism 81R (see FIG. 5) is configured to perform a minute drive in the X direction, a minute rotation in the θ direction, and a scan drive in the Y direction. The reticle stage drive mechanism 81R uses a linear motor similar to the wafer stage device as a drive source, but is shown as a simple block in FIG. 5 for convenience of explanation. Therefore, reticle stages RST1, RST
The reticles R1 and R2 on the second wafer 2 are selectively used, for example, in the case of double exposure, so that any of the reticles R1 and R2 can be scanned synchronously with the wafers W1 and W2.

These reticle stages RST1 and RS
On T2, a reticle stage RS is provided on the side surface in the + X direction.
Moving mirrors 82A and 82B made of the same material (for example, ceramics) as T1 and RST2 are respectively extended in the Y direction, and a laser interferometer (hereinafter referred to as a laser interferometer) is directed toward the + X direction reflecting surfaces of these moving mirrors 82A and 82B. (Hereinafter simply referred to as “interferometer”) 83X1 to 83X5 are irradiated with measurement beams 91X1 to 91X5 each formed of a laser beam.
In 1 to 83X5, the positions of the reticle stages RST1 and RST2 in the X direction are measured by receiving the reflected light and measuring the relative displacement with respect to a predetermined reference plane.
Here, the measurement beam 91X3 from the interferometer 83X3 is
Actually, each of the reticle stages RST1 and RST2 has an X-direction position and a yawing amount (around the Z-axis) based on these two measured values, which have two measurement beams separated in the Y-direction that can independently measure displacement. Angle of rotation).

In this example, the measurement beams 91X1 to 91X5
Are set shorter than the widths of the moving mirrors 82A and 82B in the Y direction.
A and 82B always include one of the measurement beams 91X1 to 91X.
X5 has been irradiated. Also, at a certain time, two adjacent measurement beams (for example, 91X1 and 91X2) are simultaneously irradiated on the same movable mirror (for example, 82B),
In this state, it can be considered that the corresponding interferometers 83X1 and 83X2 partially overlap the measurement range. As a result, the measurement values of the interferometers 83X1 to 83X4 can be sequentially transferred to the measurement values of the interferometers 83X2 to 83X5 with high accuracy, as described later. The measurement values of the interferometers 83X1 to 83X5 are supplied to the stage control device 38 shown in FIG. Rotation control of reticle stages RST1 and RST2 and position control in the X direction are performed via drive mechanism 81R.

On the other hand, in FIG. 6, at the end of the first reticle stage RST1 in the −Y direction along the scanning direction,
Corner cube 89A, 89B as a pair of movable mirrors
Is installed. Then, these corner cubes 89 are obtained from a pair of double-pass interferometers (not shown).
A and 89B are irradiated with measurement beams 91Y1 and 91Y2 (represented by one measurement beam in FIG. 6) each composed of two laser beams, and predetermined by a pair of interferometers (not shown). Is measured relative to reticle stage RST1 in the Y direction. A pair of corner cubes 89C and 89D are also provided at the + Y direction ends of the second reticle stage RST2, and a pair of double-pass interferometers 83Y3 and 83Y4 are provided.
The measurement beams 91Y3 and 91Y4 (actually, two laser beams each) are emitted to these corner cubes 89C and 89D from the interferometer 83Y.
Reticle stage RST by 3,83Y4
2, the displacement in the Y direction is measured.

The measured values of these double-pass interferometers are also supplied to the stage controller 38 shown in FIG. 5, and the Y values of the reticle stages RST1 and RST2 are determined based on the measured values.
The position of the direction is controlled. That is, in this example, the interferometers 83X1 to 83X5 having the measurement beams 91X1 to 91X5 are used.
And measurement beams 91Y1, 91Y2 and measurement beam 91
An interferometer system for a reticle stage is composed of two pairs of double-pass interferometers having Y3 and 91Y4. The interferometers 83X1 to 83X5 are represented by the interferometer 83 in FIG. 5, and the movable mirrors 82A and 82B and the measurement beams 91X1 to 91X5 are respectively shown in FIG.
2 and the measurement beam 91X.

Next, wafer stages WST1, WST2
An interferometer system that manages the position of the image will be described with reference to FIGS. As shown in FIGS. 5 to 7, the wafer passes along the axis parallel to the X axis passing through the center (optical axis AX1) of the projection image of the projection optical system PL1 and the respective detection centers of the alignment systems 88A and 88B. The measurement beam 92X2 composed of a three-axis laser beam is emitted from the interferometer 87X2 to the reflection surface 84X on the side surface in the −X direction of the stage WST1. Similarly, interferometer 87X5 irradiates measurement beam 92X5 composed of a three-axis laser beam to reflective surface 85X on the side in the + X direction of wafer stage WST2. The interferometers 87X2 and 87X5 measure the relative displacement of each reflection surface in the X direction from the reference position by receiving the reflected light.

In this case, as shown in FIG. 6, the measurement beams 92X2 and 92X5 are three-axis laser beams capable of performing displacement measurement independently of each other.
Corresponding interferometers 87X2 and 87X5 measure the positions of wafer stages WST1 and WST2 in the X direction, respectively, and also tilt angles (rotation angles around Y axis) of each stage.
Measurement and yawing angle (rotational angle around the Z axis) can be measured. In this case, the wafer stage W of the present example
In ST1 and WST2, as shown in FIG. 6, Z leveling stages LS1 and LS2 for performing minute driving in the Z direction, tilt angle driving, and rotational driving around the Z axis, respectively, as shown in FIG. Provided, but Z
The leveling stages LS1 and LS2 are actually located below the reflecting surfaces 84X and 85X. Therefore, the driving amounts for the tilt angle control and the yawing angle control of the wafers W1 and W2 are all the interferometers 87X2 and 87X5.
Can be monitored.

The X-axis measurement beams 92X2, 92X
Numeral 5 always irradiates the reflecting surfaces 84X and 85X of the wafer stages WST1 and WST2 in the entire movement range of the wafer stages WST1 and WST2. Therefore, in the X direction, the X of the wafer stages WST1 and WST2 can be set at any time such as at the time of exposure using the projection optical system PL1 or at the time of using the alignment systems 88A and 88B.
The position in the direction is managed based on measurement values using the measurement beams 92X2 and 92X5.

As shown in FIGS. 6 and 7, the + Y-direction side surfaces of wafer stages WST1 and WST2 are processed into reflecting surfaces 84Y and 85Y as movable mirrors, and optical axis AX1 of projection optical system PL1 is moved. The measurement beam 92Y3 parallel to the Y axis passes from the interferometer 87Y3 to the reflecting surfaces 84Y and 85.
Y is irradiated. Also, alignment systems 88A, 8A
8Y respectively having measurement beams 92Y1 and 92Y5 parallel to the Y-axis passing through the respective detection centers of 8B.
1,87Y5 is also provided. In the case of this example, wafer stages WST1, WST during exposure using projection optical system PL1
In the position measurement in the Y direction in ST2, the measurement value of the interferometer 87Y3 having the measurement beam 92Y3 is used, and the wafer stage WST when the alignment system 88A or 88B is used.
For the position measurement in the Y direction of 1 or WST2, the measurement value of the interferometer 87Y1 or 87Y5 is used, respectively.

Therefore, the measurement beams of the Y-axis interferometers 87Y1, 87Y3, and 87Y5 may deviate from the reflecting surfaces 84Y and 85Y of the wafer stages WST1 and WST2 depending on each use condition. Therefore, in this example, the interferometer 87X
Measuring beam 92Y2 parallel to the Y axis between 1 and 87Y3
87Y2 having an interferometer 87Y3 and 87
By providing an interferometer 87Y4 having a measurement beam 92Y4 parallel to the Y axis between Y5, wafer stage WST
1, the measurement surfaces from at least one interferometer are always irradiated on the reflection surfaces 84Y and 85Y of the WST2. For this reason, assuming that the width in the X direction of the reflecting surfaces 84Y and 85Y as the movable mirror is DX1, the measurement beam 92
The distance DX2 in the X direction between Y1, 92Y2,..., 92Y5 is set smaller than the width DX1. As a result, two adjacent measurement beams among the measurement beams 92Y1 to 92Y5 always irradiate the reflecting surfaces 84Y and 85Y at the same time (they have a partially overlapping measurement range). In this state, the measurement values are transferred from the first interferometer to the second interferometer. Thus, wafer stages WST1 and WST2 are positioned with high reproducibility and high accuracy even in the Y direction.

The measurement beam 9 for position measurement in the Y direction
Since the 2Y1, 92Y3, and 92Y5 are composed of two-axis laser beams that can perform position measurement independently of each other in the Z direction, the corresponding interferometers 87Y1, 87Y3,
87Y5 are reflection surfaces 84Y and 85Y of the measurement target, respectively.
In addition to the position in the Y direction, a tilt angle (tilt angle) around the X axis can be measured. In this example, the interferometer 87
A total of seven interferometers X2, 87X5, 87Y1 to 87Y5 constitute an interferometer system for managing the two-dimensional coordinate position of wafer stages WST1 and WST2. In this example, as described later, wafer stage WST
1 and WST2 perform an exposure sequence while the other performs a wafer exchange and a wafer alignment sequence. At this time, in order to prevent mechanical interference between both stages, each interferometer The stage control device 38 controls the position and speed of the wafer stages WST1 and WST2 based on the measured values.

Next, the illumination system and the control system of this embodiment will be described.
A description will be given based on FIG. In FIG. 5, exposure light composed of pulse laser light emitted from a light source unit 40 including an excimer laser light source such as an exposure light source such as KrF, ArF, or F ₂ and a dimming system (a dimming plate or the like) is applied to a shutter 4.
After passing through the second lens 2, the light is deflected by a mirror 44, shaped into an appropriate beam diameter by beam expanders 46 and 48, and is incident on a first fly-eye lens 50. The exposure light emitted from the first fly-eye lens 50 is
2. The light enters the second fly-eye lens 58 via the vibration mirror 54 and the lens 56. This second fly-eye lens 5
Exposure light emitted from 8 passes through a lens 60 and reaches a fixed blind 62 installed at a position conjugate with the reticle R1 (or R2), where its cross-sectional shape is defined in a predetermined shape. The light passes through the movable blind 64 disposed at a position slightly defocused from the conjugate plane of the reticle R, passes through the relay lenses 66 and 68, and becomes a light having a uniform illuminance distribution. The illumination area IA (see FIG. 6) is illuminated.

Next, the control system of the present embodiment is mainly composed of
The exposure control unit 70 and the stage control unit 38 which are under the control of 0. For example, when exposing the pattern of the reticle R1 to the wafer W1, the exposure control device 70 instructs the shutter driving device 72 to start the shutter driving before the synchronous scanning of the reticle R1 and the wafer W1 is started. The shutter 74 is opened by driving the unit 74.

Thereafter, the reticle R1 and the wafer W are
1, ie, reticle stage RST1 and wafer stage W
Synchronous scanning (scan control) with ST1 is started. The synchronous scanning is performed by measuring beams 92Y3 and 92X2 of the interferometer system for the wafer stage and measuring beams 91Y1, 91Y2 and 91Y2 of the interferometer system for the reticle stage.
While monitoring the measurement value of 91X3, the stage control device 3
8 by controlling the stage drive system 81W and the reticle stage drive mechanism 81R.

When the two stages RST1 and WST1 are driven at a constant speed with the projection magnification ratio as the speed ratio within a predetermined synchronization error, the exposure control unit 70 instructs the laser control unit 76 to output a pulse. Light emission is started. Thus, the rectangular illumination area IA (see FIG. 6) of reticle R1 is illuminated by the exposure light, and the image of the pattern in the illumination area IA is reduced to 1/5 by projection optical system PL1.
The wafer W1 is reduced by a factor of two and projected onto a wafer W1 having a surface coated with a photoresist. Here, as is clear from FIG. 6, the width of the illumination area IA in the scanning direction is narrower than the pattern area on the reticle R1, and the entire area of the pattern area is scanned by synchronously scanning the reticle R1 and the wafer W1. Are sequentially transferred to the shot area on the wafer. At the time of this exposure, the exposure control device 70 controls the mirror driving device 78
To drive the vibrating mirror 54 to reduce uneven illuminance due to interference fringes generated by the two fly-eye lenses 50 and 58.

Further, the reticle R1 is controlled so that the exposure light passing outside the pattern area on the reticle R1 (outside the light-shielding band) does not leak near the edge of each shot area on the wafer W1 during the scanning exposure. The movable blind 64 is driven and controlled by the blind control device 39 in synchronization with the scanning of the wafer and the wafer W1, and a series of these synchronous operations are managed by the stage control device. Further, the main controller 90 corrects the start position of the reticle stage and the wafer stage, which perform synchronous scanning during scanning exposure, for example, by correcting the stage position with respect to the stage controller 38 which controls the movement of each stage. Indicate the value.

Next, as described above, reticle stages RST1 and RST2 and wafer stage WST1
A plurality of interferometers whose measurement ranges partially overlap each other are arranged in WST2, and are configured so that the measurement values of the interferometers are sequentially transferred. Hereinafter, wafer stage WST2 of FIG. 7 and two Y-axis interferometers 87 will be described.
Taking Y3 and 87Y4 as an example, the operation of passing the measurement values of the interferometer, that is, the operation of presetting the measurement values of the interferometer will be described with reference to FIGS.

First, the wafer stage W at the position shown in FIG.
When ST2 moves in the -X direction, measurement beam 92Y4 stops entering reflecting surface 85Y as a moving mirror of wafer stage WST2 during this movement. Conversely, when wafer stage WST2 moves in the + X direction, measurement beam 92Y3 stops entering reflecting surface 85Y during this movement. Therefore, the measurement values are transferred between the interferometers 87Y4 and 87Y3 with high accuracy, and
It is necessary to measure the Y coordinate of wafer stage WST2 using any one of 4, 87Y3 in a state having reproducibility.
For this reason, in this example, the following measures are taken.

FIG. 8A shows the wafer stage WS of FIG.
FIG. 8A is a plan view showing T2. In FIG. 8A, the displacement of wafer stage WST2 in the X direction is measured by X-axis interferometer 87X5 and in Y direction of wafer stage WST2.
The displacement in the direction is measured by two interferometers 87Y3 and 87Y4. The distance DX2 between the measurement beams 92Y3 and 92Y4 of the interferometers 87Y3 and 87Y4 in the X direction is the width DX1 of the reflection surface 85Y of the wafer stage WST2 in the X direction.
It is narrower.

Here, the interferometers 87Y4 and 87Y3 of this example
Are each a laser interferometer of a heterodyne interference system, and a common not-shown two-frequency oscillation laser (for example, a Zeeman effect type He-Ne laser light source with a wavelength of 633 nm) is used as a measurement beam light source. From this two-frequency oscillation laser, first and second light beams having polarization directions orthogonal to each other and having a predetermined frequency difference Δf (for example, about 2 MHz) are emitted coaxially as a heterodyne beam. For example, 1/10
A reference signal SR having a frequency Δf is generated by photoelectrically converting the interference light that has been branched to a certain extent and mixed by the analyzer, and this reference signal SR is used as the phase comparator 26 in the interferometers 87Y4 and 87Y3 (see FIG. 9). ).

The first and second heterodyne beams obtained by branching the above heterodyne beam by about 1/10 are supplied to the interferometers 87Y3 and 87Y4, and the interferometer 87Y4 outputs the second heterodyne beam. One of the two light beams whose polarization directions are orthogonal to each other is measured as a measurement beam 92Y4.
The other beam is referred to as a reference beam (not shown), and the reference beam is reflected by a reference mirror (not shown). Then, the reflected reference beam and the measurement beam 9 reflected by the reflection surface 85Y
By performing photoelectric conversion of interference light obtained by mixing 2Y4 with an analyzer, a measurement signal S2 having a frequency Δf and a phase change is generated and supplied to the phase comparator 26 shown in FIG. The phase difference φ2 between the reference signal SR and the measurement signal S2 is a predetermined resolution (for example, 2π / 100 (r
ad)) and supplied to the integrator 27.

At this time, measurement beams 92Y3, 92Y4
Where λ is the wavelength of the reflection surface 8 and the integer m is 1 or more.
When 5Y moves in the Y direction by λ / m (m = 2 in the single-pass system as in this example, m = 4 in the double-pass system), the phase difference φ2 changes by 2π (rad). The range of the phase difference φ2 is 0 ≦ φ2 <2π,
In the integrator 27 of FIG. 9, when the phase difference φ2 crosses 2π in the + direction, a predetermined integer (corresponding to the order of interference) N2 is 1
And when the phase difference φ2 crosses 0 in the negative direction, 1 is subtracted from the integer N2. During the measurement, the integrator 2
7 sends the measured value P2 obtained by multiplying {N1 + φ2 / (2π)} by λ / m to the stage controller 38 as the absolute position of the wafer stage WST2 in the Y direction.

Similarly, also in the interferometer 87Y3, the phase difference φ1 between the measurement signal S1 obtained from the measurement beam 92Y3 and the above-mentioned reference signal SR, and the integer N1 which increases and decreases each time this phase difference φ1 crosses 2π or 0 , And the measurement value P1 calculated from λ / m is sent to the stage control device 38. That is, interferometers 87Y3 and 87Y4 each measure the position of wafer stage WST2 in the Y direction as an absolute position within a width of λ / m.

The X-axis interferometer 87X5 of the present example is
As shown in FIG. 6, since two laser beams separated in the Y direction are provided, the rotation angle θW2 of wafer stage WST2 can be measured from the difference between the measured values of the X coordinate of reflection surface 85X by these two laser beams. . Therefore, in the "initial state" in which the wafer stage WST2 is stationary so that the rotation angle θW2 becomes 0 in the state of FIG. 8A, the integers N2 and N1 in the interferometers 87Y4 and 87Y3 are reset to 0 and Then, the measured values (initial values) P20 and P10 obtained by multiplying the measured phase differences φ2 and φ1 by {1 / (2π)} (λ / m) are taken into the stage controller 38.

Then, the stage controller 38 sets the offsets of the measured values of the interferometers 87Y4 and 87Y3 to -P20 and -P10, respectively.
The value obtained by adding the offset (−P20, −P10) to the measured values P2 and P1 supplied from the 87Y3 is used as the interferometer 8
7Y4 and 87Y3 are actually measured values P2 ′ and P1 ′. That is, the measured values P2 'and P1' accurately represent the amount of displacement of wafer stage WST2 from the initial state in the Y direction. The initial value of the measured value (P20,
P10) is stored.

Now, in FIG. 8A, it is assumed that wafer stage WST2 further moves in the -X direction and reaches the position shown in FIG. 8B. In FIG. 8B, the interferometer 87Y
The measurement beam 92Y4 of No. 4 has a reflecting surface 85Y as a movable mirror.
Is out of order. In this state, wafer stage WST
It is assumed that the Y coordinate of 2 is measured by the interferometer 87Y3. From this state, wafer stage WST2 starts moving in the + X direction again toward the position shown in FIG.
When the light beam enters the irradiation range (measurement range) of No. 4, the interferometer 87
The measurement value of Y4 is set (preset) as follows.

First, the measurement beam 92X5 (two laser beams) of the X-axis interferometer 87X5 is used to rotate the wafer stage WST2 at a rotation angle θW2 (a minute amount (ra
d)) is measured. In this state, in FIG. 8A, the measured value P1 of the Y coordinate by the interferometer 87Y3 using the measurement beam 92Y3 is obtained. However, this measured value P
1 is a direct measurement value before performing offset correction.
Then, for example, the stage controller 38 obtains an estimated value of the order N2 (N2 is an integer) of the interference of the interferometer 87Y4 and the fraction ε2 / (2π) from the measured value P1. The fraction ε2 is a value corresponding to the above φ2.

That is, the arithmetic unit in the stage controller 38 calculates the interval DX2 between the measurement beams 92Y3 and 92Y4, the measured value θW2 of the rotation angle of the wafer stage WST2, the interferometer 8
From the difference (= P20−P10) between the measured value P1 of 7Y3 and the initial value of the measured values of the interferometers 87Y4 and 87Y3, the estimated value P of the measured value P2 of the interferometer 87Y4 before the offset correction is obtained.
2 ′ is calculated as follows. P2 '= P1 + DX2.theta.W2 + (P20-P10)

For example, when the measurement accuracy of the measured value θW2 of the rotation angle is high, the estimated value P2 ′ is directly used as the interferometer 87.
It may be preset as the value of the current measurement value P2 of Y4. However, since the measurement value θW2 may include a certain measurement error, the operation unit uses the fact that the interferometer 87Y4 can measure the absolute position in the unit of the width λ / m, and P2 ′ is decomposed into an integer part and a fraction part. Therefore, the estimated value P2 ′ of the measurement value of the interferometer 87Y4
Are the remaining values of N2 times the length λ / m are fractions ε2 / (2
π). That is, the stage control device 38 calculates (estimates) the integer N2 and the fraction ε2 as follows.

N2 = g {P2 ′ / (λ / m)} (1) ε2 = {P2 ′ / (λ / m) −N2} (2π) (2) where g {X} is X A function that gives the largest integer that does not exceed. As will be described in detail later, the stage controller 38
Then, the integer (order) of the interferometer 87Y4 is obtained from the estimated value (N2, ε2) of the interference order and fraction obtained from the measurement value P1 and the phase difference (absolute phase) φ2 actually measured by the interferometer 87Y4. Determine the preset value of N2.

FIG. 9 shows a part of the stage controller 38 and a part of the interferometer 87Y4 of the present embodiment. As shown in FIG. 9, the interferometer 87Y4 has a reference signal SR output from a laser light source, for example. And a measurement signal S2 (a photoelectric conversion signal of interference light between the measurement beam and the reference beam). The phase comparator 26 receives the reference signal SR
The phase difference φ2 between the phase difference φ2 and the measurement signal S2 is detected, and the detected phase difference φ2 is output to the integrator 27 and also to the calculation processing device 28 in the stage control device 38.
The other interferometers each include a phase comparator 26 and an integrator 27.

At the time of measurement, the integrator 27 integrates the integer N2 from the change in the phase difference φ2 as described above, and ｛N2 +
The measurement value P2 obtained by multiplying φ2 / (2π)｝ by (λ / m) is output to the stage control device 38 as information indicating the movement amount of the movable mirror (in this example, the reflecting surface 85Y). However, when the measured values are transferred as in the present case, the calculation processing device 28 calculates the phase difference φ2 input from the phase comparator 26 and the estimated value ε of the fraction input from the arithmetic unit.
Compare with 2. In this comparison, when the estimated value ε2 of the estimated phase difference is close to 0 (zero) or 2π, there is a possibility that the integer N2 indicating the estimated order of the interference is shifted within a range of ± 1, and therefore, the verification is performed. To do for you. The operation of this comparison will be described with reference to FIG. For convenience, FIG.
At 0, the estimated value of N2 is the order N.

In FIGS. 10A to 10C, the horizontal axis represents the phase difference between the reference signal and the measurement signal, and particularly the order k of the interference.
= N-1, k = N, and k = N + 1. The phase difference changes by 2π within one order. FIG. 10A shows the actual phase difference φ2 and the estimated value ε2 of the phase difference.
Is smaller than π (| φ2−ε2 | <π)
Shows the case. In this case, since the actual phase difference φ2 is within the order N as shown in the figure, the order of the interference is N as the estimated value.
And the order preset value N ′ = N. FIG.
(B) shows a case where the value obtained by subtracting the estimated phase value ε2 from the actual phase difference φ2 is larger than π (φ2−ε2> π). In this case, the actual phase difference φ2 is the order N as shown in the figure.
−1, the preset value N ′ is N ′ = N−1
And FIG. 10C shows that the value obtained by subtracting the estimated phase value ε2 from the actual phase difference φ2 is smaller than −π (φ2-
ε2 <−π). In this case, since the actual phase difference φ2 is within the order N + 1 as shown, N ′ = N
+1.

The calculation processing device 28 outputs the preset value N ′ obtained as described above as the preset value RE to the integrator 27 in FIG. In the integrator 27, the preset value RE (that is, N ′) is set as a preset value of the integer N2, and the measured value P2 of the Y coordinate is obtained from the phase difference φ2 from the phase comparator 26 and the integer N ′ as follows. The calculated value is supplied to the stage control device 38, after which a normal measurement operation is performed. P2 = (λ / m) · N ′ + (λ / m) (φ2 / π) (3) As a result, the measured value P2 of the interferometer 87Y4 has substantially returned to the original value. Interferometer 87Y3
Is accurately passed to the interferometer 87Y4.

As described above, in this example, when setting the preset value in the first interferometer in which the reflected light from the mirror surface can be obtained again, the measured value of the other second interferometer is used. The calculated measurement is referred to as the order of interference of the first interferometer (N
1 or N2) as an estimate to determine
Based on the estimated interference order and the phase difference (absolute phase) φ measured by the first interferometer, a preset value of the interference order (N1 or N2) of the first interferometer, and thus the interference The preset value of the measurement value of the meter is determined. At this time, the order N2 or N1 of the interference is unknown because the measurement beam is once off the mirror surface, but the order of the interference is obtained by calculation from the measurement values of the other interferometers. The preset value can be set with the accuracy unique to the interferometer.

Note that, when the apparatus is started or when a measurement error is mixed in all the measured values for some reason and it becomes necessary to reset the measured values of all the interferometers, the calculation processing apparatus shown in FIG. It is necessary to send the order N2 = 0 to 28 and to set the output (preset value) RE (= 0) of the calculation processing device 28 in the integrator 27 in the same manner. In this case, after all, only the value corresponding to the phase difference (absolute phase) φ2 is set in the integrator 27 (interferometer 87Y4). Similarly, the initial value of the interferometer 87Y3 is also the phase difference φ
This is a value corresponding to 1.

The output P2 of the integrator 27 may be fed back to the calculation processing device 18 as needed. In this case, for example, after resetting the integrator 27,
The preset value can be set in the integrator 27 including the amount of displacement of the wafer stage until the reset value is set in the integrator 27 from the calculation processing device 28.
At this time, a more precise initial value is set in consideration of the amount of displacement of the wafer stage from when the reflected light from the wafer stage can be received until the preset value RE2 is set in the integrator 27. Will be able to do.

In this example, when wafer stage WST2 moves, side surface 85Y of wafer stage WST2 moves.
Is required to be irradiated with any one of the measurement beams from the interferometers 87Y3 to 87Y5. Therefore, in this example, the interval between the measurement beams (for example, FIG.
DX2) between the measurement beams 92Y3 and 92Y4 shown in FIG.
However, the interferometer is arranged so as to be shorter than the width DX1 of the wafer stage WST2 in the X direction.

Further, reticle stage RST1, FIG.
Interferometers 83X1-83 for measuring the position of RST2
At X5, the initial value (preset value) of the interferometer is set in the same manner, and the measurement value is transferred based on this. Next, in the projection exposure apparatus of this example, first and second transfer systems for exchanging wafers with wafer stages WST1 and WST2 are provided.

As shown in FIG. 11, the first transfer system exchanges wafers with wafer stage WST1 at the wafer loading position on the left, as will be described later. The first transport system includes a first transport system extending in the Y-axis direction.
Loading guide 96A, and first and second sliders 97 that move along the loading guide 96A.
A, 97C, an unload arm 98A attached to the first slider 97A, a load arm 98C attached to the second slider 97C, and the like.
And a first center-up 9 comprising three vertically moving members provided on wafer stage WST1.
9.

The operation of exchanging wafers by the first transfer system will be briefly described. Here, as shown in FIG. 11, a case where wafer W1 'on wafer stage WST1 at the left wafer loading position and wafer W1 carried by the first wafer loader are exchanged will be described. First, in the main controller 90,
The vacuum suction of the wafer holder (not shown) on wafer stage WST1 is turned off to release the suction of wafer W1 '. Next, main controller 90 raises center-up 99 by a predetermined amount via a center-up drive system (not shown). Thereby, the wafer W1 'is lifted to a predetermined position. In this state, main controller 90 moves unload arm 98A directly below wafer W1 'via a wafer loader controller (not shown). In this state, main controller 90 lowers center-up 99 to a predetermined position, transfers wafer W1 'to unload arm 98A, and then starts vacuum suction of unload arm 98A. Next, the main controller 90 causes the wafer loader controller to retract the unload arm 98A and load arm 98A.
Instruct the start of movement of C. This causes the unload arm 98A to start moving in the −Y direction in FIG. 11, and the load arm 98C holding the wafer W1 moves
When the wafer W comes above ST1, the vacuum suction of the load arm 98C is released by the wafer loader control device, and then the center-up 99 is driven upward to transfer the wafer W1 onto the wafer stage WST1.

Further, as shown in FIG. 12, the second transfer system for transferring a wafer to and from wafer stage WST2 is symmetrical to the first transfer system, and has a second loading guide 96B and a second transfer guide 96B. , The sliders 97B and 97D moving along the loading guide 96B, the unload arm 98B attached to the third slider 97B, the load arm 98D attached to the fourth slider 97D, and the like. The load arm 98D holds a wafer W2 ′ to be exposed next.

Next, the parallel processing by the two wafer stages WST1 and WST2 of the projection exposure apparatus of this embodiment will be described with reference to FIGS. FIG. 11 shows a projection optical system PL1 on wafer W2 on wafer stage WST2.
FIG. 11 is a plan view showing a state in which a wafer is being exchanged between the wafer stage WST1 and the first transfer system at the left loading position as described above while the exposure is being performed via. I have. In this case, the wafer stage WS
On T1, an alignment operation is performed following the wafer exchange as described later. In FIG. 11, the position control of wafer stage WST2 during the exposure operation is performed based on the measurement values of measurement beams 92X5, 92Y3 of the interferometer system, and the position of wafer stage WST1 at which the wafer exchange and the alignment operation are performed. Control is
The measurement is performed based on the measurement values of the measurement beams 92X2 and 92Y1 of the interferometer system. For this reason, main controller 9 in FIG.
At 0, the stage controller 38 is instructed to set an initial value (preset) of a measurement value of an interferometer, which will be described later, before performing wafer exchange and alignment operation.

Subsequent to the wafer exchange and the initial value setting of the interferometer, search alignment is performed. The search alignment performed after the wafer exchange is a pre-alignment performed again on wafer stage WST1 because a positional error is large only by the pre-alignment performed during transfer of wafer W1. Specifically, stage W
The positions of three search alignment marks (not shown) formed on wafer W1 mounted on ST1 are measured using an LSA-based sensor of alignment system 88A in FIG. 5, and based on the measurement results. The wafer W1 is aligned in the X, Y, and θ directions. The operation of each unit during the search alignment is controlled by main controller 90.

After completion of the search alignment, fine alignment for obtaining the arrangement of each shot area on the wafer W1 by the EGA (Enhanced Global Alignment) method is performed. More specifically, the wafer stage WST1 is sequentially moved based on the designed shot array data (alignment mark position data) while controlling the position of the wafer stage WST1 by an interferometer system (measurement beams 92X2, 92Y1). A predetermined shot area (sample shot) on the wafer W1
The position of the alignment mark of FIG.
All the shot array data are calculated by a least square method statistical calculation based on the measurement result and the shot array design coordinate data based on the measurement by the FIA system sensor A or the like. The operation of each unit at the time of this EGA type fine alignment is controlled by main controller 90 in FIG.
The above calculation is performed by main controller 90.

While the wafer exchange and alignment operations are being performed on wafer stage WST1,
On wafer stage WST2 side, two reticles R1,
Using R2, changing the exposure condition continuously
Double exposure is performed by the AND scan method. More specifically, E is set in advance in the same manner as the wafer W1 described above.
Fine alignment by GA method is performed,
After sequentially moving the shot areas on the wafer W2 below the optical axis of the projection optical system PL1 based on the shot arrangement data on the wafer W2 obtained as a result, the reticle in FIG. Stage RST1 (or R
Scan exposure is performed by synchronously scanning ST2) and wafer stage WST2 in the scanning direction. Exposure to all shot areas on the wafer W2 is performed continuously even after the reticle is replaced. As a specific exposure sequence of the double exposure, after sequentially performing scanning exposure on each shot area of the wafer W2 using the reticle R2, the reticle stages RST1 and RST2 are moved by a predetermined amount in the + Y direction to advance the reticle R1. After setting the start position, scanning exposure is performed. At this time, since the reticle R2 and the reticle R1 have different exposure conditions (illumination conditions such as annular illumination and deformed illumination, and exposure amount) and transmittance, it is necessary to change each condition in advance based on exposure data and the like. There is. The operation of each part of the wafer W2 during the double exposure is also controlled by the main controller 90.

In the exposure sequence and the wafer exchange / alignment sequence performed in parallel on the two wafer stages WST1 and WST2 shown in FIG. 11, the previously completed wafer stage enters a waiting state, and both operations are performed. Is completed, the movement of wafer stages WST1 and WST2 is controlled to the position shown in FIG. Then, wafer W2 on wafer stage WST2, for which the exposure sequence has been completed, is replaced at the right loading position, and wafer W1, on wafer stage WST1, for which the alignment sequence has been completed, undergoes an exposure sequence under projection optical system PL1. Is At the right loading position shown in FIG. 12, the above-described wafer exchange operation and the alignment sequence are executed similarly to the left loading position.

As described above, in this example, while the two wafer stages WST1 and WST2 are independently moved in the two-dimensional direction, the exposure sequence and the wafer exchange / alignment sequence are performed on the wafers W1 and W2 on each wafer stage. Are performed in parallel to improve the throughput. However, when two operations are simultaneously performed using two wafer stages, the operation performed on one wafer stage may affect the operation performed on the other wafer stage as a disturbance factor. Conversely, there are operations in which operations performed on one wafer stage do not affect operations performed on the other wafer stage. Therefore, in this example, of the operations that are performed in parallel, the operations that do not become operations that cause disturbances are divided into
The timing of each operation is adjusted so that operations that cause disturbance or operations that do not cause disturbance are performed simultaneously.

For example, during the scanning exposure, since the wafer W1 and the reticles R1 and R2 are synchronously scanned at a constant speed, it does not become a disturbance factor, and it is necessary to eliminate other disturbance factors as much as possible. Therefore, during the scanning exposure on one wafer stage WST1, the timing is adjusted so as to be stationary in the alignment sequence performed on wafer W2 on the other wafer stage WST2. That is, since the measurement in the alignment sequence is performed while the wafer stage WST2 is stationary, the mark measurement can be performed in parallel during the scanning exposure without causing disturbance in the scanning exposure. On the other hand, also in the alignment sequence, high-precision measurement can be performed during scanning exposure because the movement is at a constant speed and no disturbance occurs.

The same can be considered when exchanging wafers. In particular, vibration and the like generated when the wafer is transferred from the load arm to the center-up can be a disturbance factor. The transfer of the wafer may be performed according to the following. These timing adjustments are performed by the main controller 90.
Done by

Further, in this example, since double exposure is performed using a plurality of reticles, high resolution and DOF (depth of focus) can be improved. However, in this double exposure method, since the exposure step must be repeated at least twice, when a single wafer stage is used, the exposure time becomes long and the throughput is greatly reduced. However, by using the projection exposure apparatus having the two wafer stages according to the present embodiment, the throughput can be greatly improved, and the high resolution and the DOF can be improved.

Note that the scope of application of the present invention is not limited to this, and the present invention can be suitably applied even when exposure is performed by a single exposure method. By using two wafer stages, it is possible to obtain almost twice as high throughput as in a case where the single exposure method is performed using one wafer stage. Note that, in the second embodiment, as in the first embodiment, a measurement stage for measuring the state of the exposure light or the imaging characteristics may be further provided. Further, in this example, the wafer stage is driven by a combination of a one-dimensional motor, but may be two-dimensionally driven by a plane motor as in the first embodiment.

The projection exposure apparatus of the present embodiment has a reticle stage RST (RST1, RST)
ST2), wafer stage WST (WST1, WST)
2) is assembled, and the optical adjustment of the projection optical system PL (PL1) including a plurality of lenses is performed.
It can be manufactured by comprehensive adjustment (electrical adjustment, operation confirmation, etc.). It is desirable that the projection exposure apparatus be manufactured in a clean room in which temperature, cleanliness, and the like are controlled.

In the above embodiment, the step
The present invention is applied to an AND-scan type projection exposure apparatus, but the present invention is not limited to this. A step-and-repeat type projection exposure apparatus, a proximity type exposure apparatus, or EUV light such as X-rays Exposure device that uses as an exposure beam or electron beam (energy beam) as a light source (energy beam)
The same can be applied to the charged particle beam exposure apparatus described above. Further, the present invention may be used not only in an exposure apparatus but also in an inspection apparatus using a stage for positioning a wafer or the like, a repair apparatus, or the like.

Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

[0134]

According to the first stage apparatus of the present invention,
By providing a movable stage for each individual function or for each of a plurality of predetermined function groups, each movable stage can be downsized and driven at high speed and with high accuracy. In addition, each of the plurality of movable stages can be moved in a range larger than the measurement range of the first measurement system. Further, when each movable stage enters the measurement range of the first measurement system, the first stage is moved to the first measurement system. The measuring system can measure the position of the movable stage with high reproducibility and high accuracy.

Next, according to the second stage apparatus of the present invention, the positions of the plurality of movable stages can be measured in a wide measurement range with high reproducibility and high accuracy. Also,
The position of the movable stage can be measured with high accuracy by the first measurement system only by matching the measurement result of the first measurement system with the measurement result of the second measurement system, so that the throughput can be improved.

Next, according to the first exposure apparatus of the present invention,
Since the stage device of the present invention is provided, for example, when measuring the position of the movable stage with an interferometer, the movable mirror can be made smaller than the movable range of the movable stage, and the weight of the movable stage can be reduced. Can be smaller. Therefore, it is easy to move the movable stage at high speed, exposure can be performed using a double exposure method or the like with high throughput, and resolution and depth of focus can be improved.

Next, according to the second exposure apparatus of the present invention,
Since the first movable stage used for the original exposure has only the minimum functions necessary for the exposure, the size of the first movable stage can be minimized. In addition, the weight can be reduced and the throughput can be improved. On the other hand, since the characteristic measuring device that is not directly required for exposure and measures the characteristic when transferring the pattern of the mask is mounted on another second movable stage, the characteristic measuring device is used for transferring the pattern of the mask. Can also be measured. In addition, since the stage device of the present invention is provided, the positions of the plurality of movable stages can be measured with high accuracy.

Next, according to the third exposure apparatus of the present invention,
For example, while the exposure operation is being performed on one of the plurality of movable stages, the loading and unloading of the substrate and the alignment operation can be performed on another movable stage, so that the throughput can be improved. Next, according to the fourth exposure apparatus of the present invention, the first movable stage used for the original exposure is provided with only the minimum function necessary for the exposure. Can be reduced in size and weight to improve throughput. On the other hand, since the characteristic measuring device for measuring the imaging characteristics of the projection optical system is not directly required for exposure and is mounted on another second movable stage, the imaging characteristics can also be measured.

Next, according to the first positioning method of the present invention, the positions of the plurality of movable stages can be quickly measured and positioned with high accuracy. Similarly, according to the second positioning method of the present invention, the positions of the plurality of movable stages can be quickly measured and positioned with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a projection exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a wafer stage WST and a measurement stage 14 of FIG.

FIG. 3 is a plan view showing a reticle stage RST and a measurement stage 5 of FIG.

FIG. 4 is a plan view for describing a case where the state of exposure light and the like are measured using a measurement stage in the first embodiment.

FIG. 5 is a schematic configuration diagram of a projection exposure apparatus according to a second embodiment of the present invention.

FIG. 6 shows two wafer stages W in the embodiment of FIG.
ST1, WST2 and two reticle stages RST
1 is a perspective view showing a positional relationship among RST2, a projection optical system PL1, and alignment systems 88A and 88B.

FIG. 7 is a plan view showing a configuration of a drive mechanism of the wafer stage in FIG. 5;

FIG. 8 is a diagram for explaining a measurement value setting of an interferometer performed in a second embodiment of the present invention.

FIG. 9 is a diagram illustrating a schematic configuration of a part of a signal processing system used in an interferometer system according to a second embodiment of the present invention.

FIG. 10 is a diagram illustrating an example of signal processing in an interferometer system according to a second embodiment of the present invention.

FIG. 11 shows two wafer stages WST1 and WST2.
FIG. 9 is a plan view showing a state in which a wafer exchange / alignment sequence and an exposure sequence are performed by using FIG.

FIG. 12 is a diagram showing a state where switching between the wafer exchange / alignment sequence and the exposure sequence in FIG. 11 is performed.

[Explanation of symbols]

MA, MB, MC1, MC2, MD1, MD2: Reference mark, R, R1, R2: Reticle, RA, RB: Reticle alignment microscope, RST, RST1, RST2 ...
Reticle stage, W, W1, W2 ... wafer, WST,
WST1, WST2: wafer stage, 5: measurement stage, 7X1, 7X2, 7Y, 8Y, 15X1, 15X
2, 15Y laser interferometer, 10 main control system, 11 imaging characteristic calculation system, 13 base plate, 14 measurement stage, 1
6 wafer alignment sensor, 26 phase comparator, 2
7: Integrator, 28: Calculation processing device, 38: Stage control device, 83X1 to 83X5, 83Y1 to 83Y4, 87
X2, 87X5, 87Y1 to 87Y5 ... interferometer, 88
A, 88B: alignment system, 90: main controller

Continued on the front page F term (reference) 2H097 AA12 BA01 KA03 KA28 KA38 LA10 5F046 AA13 CC01 CC02 CC13 CC16 CC17 DB05 DB10 DC05 DC12

Claims (9)

[Claims] 1. A plurality of movable stages movably arranged independently of each other along a predetermined moving surface, and a position of one of the plurality of movable stages is measured within a predetermined measurement range. A first measurement system, comprising: a displacement amount from a predetermined reference position within the measurement range of the movable stage with respect to each of the plurality of movable stages; The second to measure the degree of match
A stage device comprising: a measurement system; and correcting a measurement value of the first measurement system based on a measurement result of the second measurement system. 2. A plurality of movable stages movably arranged independently of each other along a predetermined moving surface; and a position of one of the plurality of movable stages within a predetermined first measurement range. A first measurement system for measuring with
A stage device comprising: a first device for each of the plurality of movable stages;
A second measurement system that continuously measures the position within a second measurement range that partially overlaps the measurement range of the first and second measurement systems; and a measurement of the two measurement systems based on the measurement results of the first and second measurement systems. A stage device comprising: a control system for correcting a result. 3. The stage apparatus according to claim 2, wherein the first measurement system is an interferometer, and the second measurement system is a plurality of interferometers having measurement ranges that partially overlap each other. A stage device characterized by the above-mentioned. 4. An exposure apparatus comprising the stage device according to claim 1, 2 or 3, wherein a mask on which patterns different from each other are formed is placed on the plurality of movable stages of the stage device. An exposure apparatus for transferring a mask pattern on a plurality of movable stages onto a substrate while alternately positioning the pattern. 5. An exposure apparatus comprising the stage device according to claim 1, 2 or 3, wherein a mask is placed on a first movable stage of the plurality of movable stages of the stage device, and 2. An exposure apparatus, wherein a characteristic measuring device for measuring characteristics when transferring the pattern of the mask is mounted on the movable stage 2, and the pattern of the mask is transferred onto a substrate. 6. An exposure apparatus comprising the stage device according to claim 1, 2 or 3, wherein a substrate is placed on each of the plurality of movable stages of the stage device, and An exposure apparatus, wherein a predetermined mask pattern is alternately exposed on the plurality of substrates while being alternately positioned at an exposure position. 7. An exposure apparatus comprising: the stage device according to claim 1, 2, or 3, and a projection optical system, wherein the stage device has a plurality of movable stages on a first movable stage. A substrate is mounted, and a characteristic measuring device for measuring an imaging characteristic of the projection optical system is mounted on a second movable stage, and a predetermined mask pattern is formed on the substrate on the first movable stage. An exposure apparatus that performs exposure via the projection optical system. 8. A positioning method using the stage device according to claim 1, wherein when one of the plurality of movable stages enters a measurement range of the first measurement system, The amount of displacement of the movable stage from the predetermined reference position within the measurement range, or the degree of coincidence with the reference position, is measured by the second measurement system, and the measurement value of the first measurement system is measured based on the measurement result. A positioning method using a stage device, wherein correction is performed. 9. A positioning method using the stage device according to claim 2, wherein one of the plurality of movable stages is configured to perform the first measurement from a side of the second measurement range. When entering the range, the position of the movable stage is simultaneously measured by the first and second measurement systems, and the first
A positioning method using a stage device, wherein a measurement result of the measurement system is matched with a measurement result of the second measurement system.