JP4264676B2 - Exposure apparatus and exposure method - Google Patents

Exposure apparatus and exposure method Download PDF

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Publication number
JP4264676B2
JP4264676B2 JP33978998A JP33978998A JP4264676B2 JP 4264676 B2 JP4264676 B2 JP 4264676B2 JP 33978998 A JP33978998 A JP 33978998A JP 33978998 A JP33978998 A JP 33978998A JP 4264676 B2 JP4264676 B2 JP 4264676B2
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Japan
Prior art keywords
stage
measurement
exposure
wafer
reticle
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JP33978998A
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JP2000164504A (en
Inventor
三郎 神谷
哲夫 谷口
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株式会社ニコン
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Priority to JP33978998A priority Critical patent/JP4264676B2/en
Priority claimed from EP98961381A external-priority patent/EP1041357A4/en
Priority claimed from US09/593,800 external-priority patent/US6897963B1/en
Publication of JP2000164504A publication Critical patent/JP2000164504A/en
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    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70Exposure apparatus for microlithography
    • G03F7/70691Handling of masks or wafers
    • G03F7/70716Stages

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes, for example, a stage device for positioning an object to be processed and the stage device, and a mask pattern is formed on a substrate in a lithography process for manufacturing a semiconductor element, a liquid crystal display element, a thin film magnetic head, or the like. The exposure apparatus used for transferring is particularly suitable for use in an exposure apparatus having various mechanisms such as an imaging characteristic measuring mechanism.
[0002]
[Prior art]
High exposure accuracy is required for an exposure apparatus of a batch exposure type (stepper type) or a scanning exposure type (step-and-scan type or the like) used when manufacturing a semiconductor element or the like. Therefore, conventionally, in an exposure apparatus, a movable mirror is fixed to each side of a reticle stage for placing and positioning a reticle as a mask or a wafer stage for placing a wafer as a substrate and moving two-dimensionally. By irradiating the movable mirror with an interferometer such as a laser interferometer, the amount of movement of the stage is continuously measured, and the stage can be positioned with high accuracy based on this measurement value. It can be done. In such a stage apparatus, normally, a three-degree-of-freedom displacement measurement of a movable stage in a two-dimensional direction and a rotational component is realized by a three-axis interferometer.
[0003]
However, in such a conventional stage apparatus, it is necessary that the measurement beam from each interferometer is always irradiated to the movable mirror in all regions of the maximum movable range (movable range) of the movable stage. In order to keep reflecting the measurement beam from each interferometer even if the movable stage is moved, the size thereof needs to be larger than the movable range.
[0004]
For this reason, if the movable range of the movable stage is to be expanded, a large moving mirror is required, and the shape of the entire stage must be increased accordingly, and therefore the stage becomes heavy and moved at high speed. The problem arises that it becomes difficult. In addition, processing a large movable mirror with a predetermined flatness is accompanied by a great deal of technical difficulty, and it is also technically difficult to fix the large movable mirror to the side surface of the movable stage without causing bending. There are difficulties. 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, resulting in a problem that the movable range of the movable stage has to be finally limited.
[0005]
As a stage device for solving such a problem, for example, there is one disclosed in Japanese Patent Laid-Open No. 7-253304. This disclosed stage apparatus can be installed from one interferometer by installing more interferometers (eg, 4 axes) than the number of degrees of freedom (eg, 3 degrees of freedom) of displacement of the movable stage. Even if the measurement beam deviates from the measurement range of the movable mirror, the remaining interferometers can measure the degree of freedom of movement of the stage. Then, once the moving mirror enters the measurement range of the one interferometer that has moved away from the moving mirror, the measurement value of the remaining interferometer is set as the initial value of the one interferometer, thereby The movement amount of the movable stage can be measured by the interferometer, and the size of the movable mirror is made smaller than the movable range of the movable stage.
[0006]
Further, in these exposure apparatuses, since it is necessary to always perform exposure with an appropriate exposure amount and with high imaging characteristics maintained, a reticle stage for positioning a reticle or a wafer stage for positioning a wafer is used. Is provided with a measuring device for measuring the state of exposure light such as the illuminance and the imaging characteristics such as the projection magnification. For example, the measurement apparatus provided in the wafer stage includes an irradiation amount monitor for measuring the incident energy of exposure light to the projection optical system, and an aerial image detection system for measuring the position and contrast of the projection image. is there. On the other hand, as a measuring apparatus provided on the reticle stage, for example, there is a reference plate on which index marks used for measuring imaging characteristics of a projection optical system are formed.
[0007]
[Problems to be solved by the invention]
As described above, in the conventional exposure apparatus, the exposure amount is optimized by using the measurement device provided on the reticle stage or the wafer stage, and high imaging characteristics are maintained. On the other hand, recent exposure apparatuses are also required to increase the throughput (productivity) of the exposure process when manufacturing semiconductor elements and the like. In addition to increasing the exposure energy per unit time as a method for improving the throughput, the stage driving speed is increased to shorten the stepping time in the batch exposure type, and the stepping time and the scanning exposure type in the scanning exposure type. There is a method for shortening the scanning exposure time.
[0008]
In order to improve the drive speed of the stage in this way, if the stage system is the same size, a drive motor with a larger output may be used. In order to achieve this, it is necessary to reduce the size and weight of the stage system. However, if a drive motor with a larger output is used as in the former case, the amount of heat generated from the drive motor increases. The amount of heat that increases in this way may cause subtle thermal deformation of the stage system, making it impossible to obtain the high positioning accuracy required by the exposure apparatus. Therefore, in order to prevent the deterioration of 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.
[0009]
In particular, in a scanning exposure type exposure apparatus, the scanning exposure time is shortened by improving the driving speed, and the throughput is greatly improved, and the miniaturization of the stage system also improves the synchronization accuracy between the reticle and the wafer, thereby forming an image. There is a great advantage that the performance and overlay accuracy are improved. However, when the reticle stage or the wafer stage is provided with various measuring devices as in the prior art, it is difficult to reduce the size of the stage.
[0010]
Furthermore, when the reticle stage or wafer stage is equipped with a measuring device for measuring the state of exposure light, imaging characteristics, etc., the measuring device usually comes with a heat source such as an amplifier, During the measurement, the temperature of the measuring device gradually increases due to the exposure light. As a result, the reticle stage or the wafer stage may be slightly thermally deformed, and the positioning accuracy and overlay accuracy may be deteriorated. At present, the degradation of positioning accuracy and the like due to the temperature rise of the measuring device is slight, but as the circuit pattern of semiconductor elements and the like becomes further miniaturized in the future, there is a need to suppress the influence of the temperature rise of the measuring device. Expected to increase.
[0011]
In this regard, the length of the movable mirror can be made smaller than the movable range of the movable stage by using the stage device disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-253304. It cannot contribute much to the miniaturization of itself. Therefore, in order to improve the throughput of the exposure process and to reduce the influence of the irradiation heat of the exposure light, further ingenuity is required.
[0012]
Further, in an exposure apparatus, particularly a projection exposure apparatus, it is required to improve resolution, depth of focus (DOF: Depth of Forcus), line width control accuracy, and the like in addition to throughput improvement. Here, the exposure wavelength is λ, and the numerical aperture of the projection optical system is N.P. A. Then, the resolution R is λ / N. A. And the depth of focus DOF is λ / (NA)2 Is proportional to For this reason, in order to improve the resolution R (reduce the value of R), the exposure wavelength λ is simply reduced, and the numerical aperture N.P. A. When is increased, the DOF becomes too small.
[0013]
In this regard, in order to manufacture a device, a wafer is formed by combining a periodic pattern such as a line and space (L / S) pattern and an isolated pattern such as a contact hole (CH) pattern. Need to be formed on top. Recently, for example, regarding a periodic pattern, as disclosed in Japanese Patent Laid-Open No. 4-225514, a technique for improving the resolution without reducing the depth of focus by a so-called modified illumination method has been developed. A phase shift reticle method has also been developed. Similarly, with respect to an isolated pattern, for example, a technique for substantially improving the depth of focus by a method such as controlling the coherence factor of illumination light has been developed.
[0014]
Against the background of such technological trends, the double exposure method has been reviewed as a method for improving the resolution without substantially reducing the depth of focus. That is, if the double exposure method is applied, a 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 optimum illumination conditions and exposure conditions, so that the whole 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 further an ArF excimer laser as exposure light, for example, to form a device pattern including an L / S pattern with a line width of up to 0.1 μm. Attempts to expose are also being considered.
[0015]
However, if this double exposure method is applied to a projection exposure apparatus having a single wafer stage, it is necessary to repeatedly execute processes such as alignment and exposure serially, so that the throughput is greatly deteriorated. There is an inconvenience. 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 way, 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 moved when each movable stage moves greatly. For example, when the movable stages are alternately positioned at the exposure positions, it is difficult to quickly position the movable stages in a reproducible state.
[0016]
  In view of the above, the present invention provides a stage apparatus having a plurality of functions.UsingThe movable part can be miniaturized in a state where a plurality of functions can be executed, the movable part can be moved at high speed, and the position of the movable part can be measured with high reproducibility.Exposure method and apparatusIt is a first object to provide
[0017]
  Furthermore, the present invention includes such a stage device, and positions the reticle or wafer while maintaining the function of measuring the characteristics when transferring the pattern of the reticle or the imaging characteristics of the projection optical system. To provide an exposure apparatus capable of downsizing the movable part forSecondObjective.
[0019]
[Means for Solving the Problems]
  The invention according to claim 1 of the present application is an exposure apparatus that forms a predetermined pattern on a substrate (W) using an exposure beam, and is a first stage that holds the substrate and can move in a predetermined region. (WST), a second stage (14) that does not hold the substrate and is movable independently of the first stage, and measures the state of the exposure beam provided on the second stage. Measuring device (20), a first measurement system (15X1, 15X2, 15Y) for measuring positional information of the first stage and the second stage, the first stage and the second stage When the second measurement system (16, 17A, 17B) for measuring the relative positional relationship from a predetermined reference position and the second measurement system is used to control the position of the second stage. 2 measurement system in the second stage A control device (10) for correcting the measurement value of the second stage by the first measurement system using the measurement result obtained in this manner, and measuring the state of the exposure beam using the measurement device; It is what has.
According to a seventh aspect of the present invention, there is provided an exposure method for forming a predetermined pattern on a substrate (W) using an exposure beam, the substrate being held by a first stage (WST) and predetermined. And a step of moving the second stage (14) having a measuring device (20) for measuring the state of the exposure beam without holding the substrate independently of the first stage. Measuring the position information of the first stage and the second stage with the first measurement system (15X1, 15X2, 15Y), and predetermined reference positions of the first stage and the second stage And measuring the relative positional relationship with the second measurement system (16, 17A, 17B), and controlling the position of the second stage using the first measurement system. Seeking for stage 2 Thereby correcting the measured value for that second stage according to a first measuring system using the measurement results, those having the steps of performing a measurement of the state of the exposure beam using the measurement device.
In addition, the following inventions are also described in the embodiments of the present invention. That is,A first stage apparatus according to the present invention includes a plurality of movable stages (WST, 14) arranged to be movable independently of each other along a predetermined moving surface, and one movable stage among the plurality of movable stages. A stage apparatus including a first measurement system (15X1, 15X2, 15Y) that measures a position within a predetermined measurement range, and each of the plurality of movable stages is within the measurement range of the movable stage. And a second measurement system (16, 17A, 17B) for measuring the amount of displacement from a predetermined reference position or the degree of coincidence with the reference position, and the first measurement based on the measurement result of the second measurement system. The measurement value of the system is corrected.
[0020]
According to the first stage apparatus of the present invention, when a plurality of functions such as exposure and characteristic measurement are executed, a movable stage is assigned to each function (or each of a plurality of function groups), and a plurality of functions are assigned. A movable stage (movable part) is provided. As a result, each movable stage can be miniaturized and can be driven at a high speed. However, when a plurality of movable stages are simply provided and a relative displacement measurement system, for example, a uniaxial laser interferometer, is provided as the first measurement system, if each movable stage moves greatly, the measurement beam of the laser interferometer is changed. In order to be interrupted, some origin setting operation is required. Therefore, in the present invention, the second measurement system (16, 17A, 17B) is provided as a kind of absolute value measurement system.
[0021]
When one movable stage (WST) of the plurality of movable stages enters the measurement range from the outside of the measurement range of the first measurement system, the second measurement system (absolute value measurement system) ) To measure the amount of displacement of the movable stage from a predetermined reference position within the measurement range, and for example, by presetting the amount of displacement to the measurement value of the first measurement system, The measured value 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 becomes a predetermined level or more, the measurement value of the first measurement system May be reset or preset to a predetermined value. As a result, each movable stage is positioned with high accuracy in a rapidly reproducible state.
[0022]
Next, a second stage apparatus according to the present invention includes a plurality of movable stages (WST1, WST2) that are movably arranged independently of each other along a predetermined moving surface, and one of the plurality of movable stages. A stage device including a first measurement system (87Y3) for measuring the position of a movable stage within a predetermined first measurement range, and the first measurement range for each of the plurality of movable stages. A second measurement system (87Y2, 87Y4) that continuously measures a position within a second measurement range partially overlapping with the two measurement systems based on the measurement results of the first and second measurement systems And a control system (38) for correcting the measurement result.
[0023]
According to the second stage apparatus of the present invention, a plurality of movable stages (WST1, WST2) are provided for performing double exposure, for example. As a result, if, for example, a uniaxial laser interferometer as a relative displacement measurement system is used as the first measurement system, it will deviate from the measurement beam of the laser interferometer when each movable stage is moved greatly. The problem is how to position each movable stage in a reproducible manner. On the other hand, in the present invention, for example, a single-axis (or multiple-axis) laser interferometer as a relative displacement measurement system is used as the first measurement system. When one movable stage 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 By measuring the position of the movable stage and presetting the measured value of the first measurement system in accordance with the rotation angle of the movable stage, the measured value of the second measurement system is preset. Is transferred to the second measurement system. Thereafter, the movable stage can be positioned with high accuracy in a reproducible state using the second measurement system.
[0024]
In this case, the first measurement system and the second measurement system have interference orders (integers) N1, N2 and phases (rad) φ1, φ2 (this is, for example, a phase difference between a reference signal and a measurement signal in the heterodyne interference method). And a function f (λ) of the wavelength λ of the measurement beam, f (λ) {N1 + φ1 / (2π)} and f (λ) {N2 + φ2 / (2π)} The position may be measured. When the measurement of the second measurement system becomes possible and the position of the movable stage is simultaneously measured by the first measurement system and the second measurement system, the measurement value of the first measurement system and the movable stage are measured. Of the second measurement system is estimated from the rotation angle of the second measurement system, and the second order is calculated from the second order N2 ′, the phase φ2 ′, and the phase φ2 measured by the second measurement system. It is desirable to determine a preset value of the order N2 of the measurement system. Thereafter, the measurement value of the second measurement system is set to f (λ) {N2 + φ2 / (2π)}, so that the second measurement can be performed even if a measurement error of the rotation angle of the movable stage occurs to some extent. The position of the movable stage can be measured with the inherent reproduction accuracy of the system. The function f (λ) is λ / m using an integer m of 2 or more as an example.
[0025]
Next, the first exposure apparatus according to the present invention is an exposure apparatus provided with the stage apparatus of the present invention, in which different patterns are formed on the plurality of movable stages (RST1, RST2) of the stage apparatus. (R1, R2) is placed, and the mask patterns on the plurality of movable stages are transferred onto the substrate (W1) while being alternately positioned.
[0026]
According to the first exposure apparatus of the present invention, exposure can be performed using the double exposure method, and the resolution and the depth of focus can be improved. Further, since the stage apparatus of the present invention is provided, for example, when the position of the movable stage is measured by a laser interferometer, the movable mirror installed on the movable stage should be made smaller than the movable range of the movable stage. And the weight of the movable stage can be reduced. Therefore, it becomes easy to move the movable stage at high speed, and throughput can be improved.
[0027]
Next, a second exposure apparatus according to the present invention is an exposure apparatus provided with the stage apparatus of the present invention, and the first movable stage (RST) of the plurality of movable stages (RST, 5) of the stage apparatus. A mask (R) is placed thereon, and a characteristic measuring device (6) for measuring the characteristics when the mask pattern is transferred is placed on the second movable stage (5). The pattern R) is transferred onto the substrate (W).
[0028]
According to the second exposure apparatus of the present invention, the first movable stage (RST) used for the original exposure is provided with only a minimum function necessary for the exposure, thereby providing the first exposure stage. Since the size of the movable stage can be minimized, it is possible to improve the throughput by reducing the size and weight of the stage. On the other hand, the characteristic measurement device (6) for measuring the characteristics when transferring the pattern of the mask (R) is not directly required for exposure, and is mounted on another second movable stage (5). The characteristics when the mask pattern is transferred can also be measured. Moreover, since the stage apparatus of the present invention is provided, the positions of the plurality of movable stages can be measured with high accuracy.
[0029]
Next, a third exposure apparatus according to the present invention is an exposure apparatus provided with the stage apparatus of the present invention, and the substrates (W1, W2) are respectively disposed on the plurality of movable stages (WST1, WST2) of the stage apparatus. The predetermined mask pattern is alternately exposed on the plurality of substrates while the plurality of movable stages are alternately positioned at the exposure position.
[0030]
According to the third exposure apparatus of the present invention, an exposure operation is performed on one of the plurality of movable stages (WST1, WST2) while the other movable stage (WST2) is a substrate. Loading / unloading and alignment operations can be performed, and throughput can be improved. Moreover, since the stage apparatus of the present invention is provided, the positions of the plurality of movable stages can be measured with high accuracy.
[0031]
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, 14) of the stage apparatus. A characteristic measuring device (20) for placing the substrate (W) on the first movable stage (WST) and measuring the imaging characteristics of the projection optical system on the second movable stage (14). A predetermined mask pattern is placed on the substrate on the first movable stage and exposed through the projection optical system.
[0032]
According to the fourth exposure apparatus of the present invention, the first movable stage (WST) used for the original exposure is provided with only the minimum functions necessary for the exposure, so that the first Throughput can be improved by reducing the size and weight of the movable stage (WST). On the other hand, the characteristic measurement device (20) for measuring the imaging characteristics of the projection optical system is not directly required for exposure, and is mounted on another second movable stage (14). It can be measured. Moreover, since the stage apparatus of the present invention is provided, the positions of the plurality of movable stages can be measured with high accuracy.
[0033]
Next, a first positioning method according to the present invention is a positioning method using the stage apparatus of the present invention, and one movable stage (WST) among the plurality of movable stages (WST, 14) is the first. When entering the measurement range of one 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. Based on the measurement result, the measurement value of the first measurement system is corrected. According to such a positioning method, the plurality of movable stages can be positioned with high accuracy in a state where each of the movable stages is easily reproducible.
[0034]
Next, a second positioning method according to the present invention is a positioning method using the stage apparatus of the present invention, and one of the plurality of movable stages (WST1, WST2) is subjected to the second measurement. When entering the first measurement range from the range side, the position of the movable stage is simultaneously measured by the first and second measurement systems, and the measurement result of the first measurement system is calculated based on the measurement result. It matches 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 where each of the movable stages is easily reproducible.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described below with reference to FIGS. In this example, the present invention is applied to a step-and-scan type projection exposure apparatus.
FIG. 1 shows a projection exposure apparatus of this example. In FIG. 1, during exposure, an exposure light source, a beam shaping optical system, a fly-eye lens for uniforming illuminance distribution, a light amount monitor, a variable aperture stop, a field stop, and The exposure light IL emitted from the illumination system 1 including a relay lens system or the like illuminates the 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), harmonics of YAG laser, or i-line (wavelength 365 nm) of a mercury lamp can be used. By switching the variable aperture stop in the illumination system 1, it is possible to select a desired illumination method among normal illumination methods, annular illumination, so-called modified illumination, illumination with a small coherence factor (σ value), and the like. Has been. When the exposure light source is a laser light source, its light emission timing and the like are controlled by a main control system 10 that controls the overall operation of the apparatus via a laser power source (not shown).
[0036]
The image of the pattern in the illumination area 9 (see FIG. 3) of the reticle R by the exposure light IL is projected at the projection magnification β (β is 1/4 times, 1/5 times, etc.) via the projection optical system PL. The image is reduced and 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 in the plane perpendicular to the Z-axis, the non-scanning direction (that is, in FIG. A description will be given by taking the X axis along the direction perpendicular to the paper surface and taking the Y axis along the scanning direction (that is, the direction parallel to the paper surface of FIG. 1).
[0037]
First, reticle R is held on reticle stage RST by vacuum suction, and reticle stage RST is placed on two guides 4A and 4B arranged in parallel so as to be movable in the Y direction via air bearings. ing. Furthermore, in this example, the measurement stage 5 is mounted on the guides 4A and 4B so as to be movable in the Y direction via an air bearing independently of the reticle stage RST.
[0038]
FIG. 3 is a plan view showing the reticle stage RST and the measurement stage 5. In FIG. 3, Y guides 4 A and 4 B extending in the Y direction (scanning direction) are respectively provided by a linear motor (not shown). Reticle stage RST and measurement stage 5 are placed so as to be driven in the direction. The lengths of the guides 4A and 4B are set to be longer by at least the width of the measurement stage 5 than the movement stroke of the reticle stage RST during scanning exposure. In addition, reticle stage RST is configured by combining a coarse movement stage that moves in the Y direction and a fine movement stage that can finely adjust a two-dimensional position on the coarse movement stage. Further, on the reticle mark stage RST, a pair of reference mark plates 17C1 and 17C2 are fixed in such a positional relationship that the reticle R is sandwiched in the X direction, and each of the reference mark plates 17C1 and 17C2 has, for example, a two-dimensional cross shape. 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 in advance with high accuracy and stored in the storage unit of the main control system 10.
[0039]
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 formed in a predetermined arrangement on the reference plate 6. ing. The reference plate 6 is large enough to cover the slit-shaped illumination region 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, it is not necessary to prepare a dedicated reticle for measuring the imaging characteristics, and the time required for exchanging the reticle R for actual exposure with the dedicated reticle is not required. The characteristics can be measured with high frequency, and the temporal change of the projection optical system PL can be accurately followed. The measurement stage 5 is also provided with a positioning mechanism in a very small range with respect to the X direction (non-measurement direction), and a pair of reference plates 6 are sandwiched in the X direction on the measurement stage 5. The reference mark plates 17D1, 17D2 are fixed, and two-dimensional, for example, cross-shaped reference marks MD1, MD2 are formed on the reference mark plates 17D1, 17D2, respectively. The positional relationship between the reference marks MD1 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.
[0040]
As described above, in this example, 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 only needs to have the minimum necessary scanning and positioning functions for scanning exposure, and thus the reticle stage RST is reduced in size and weight. Accordingly, the reticle stage RST can be scanned at a higher speed, so that the throughput of the exposure process is improved. Particularly in the case of reduction projection, the scanning speed of reticle stage RST is 1 / β times (for example, 4 times, 5 times, etc.) 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, the throughput is particularly improved in this example.
[0041]
Further, the laser interferometer 7Y installed in the + Y direction with respect to the guides 4A and 4B irradiates the movable mirror 24Y on the side surface in the + Y direction of the reticle stage RST with a laser beam, and biaxial laser interference installed in the + X direction. The laser beam is irradiated from the total 7X1, 7X2 to the movable mirror 24X on the side surface in the + X direction of the reticle stage RST, and the X coordinate, Y coordinate, and rotation angle of the reticle stage RST are measured by the laser interferometers 7Y, 7X1, 7X2. Measurement values are supplied to the main control system 10 of 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 measurement values. Further, the laser interferometer 8Y installed in the −Y direction with respect to the guides 4A and 4B is irradiated with a laser beam onto the movable mirror 25Y on the side surface in the −Y direction of the measurement stage 5, and is measured by the laser interferometer 8Y. The Y coordinate of the measurement stage 5 is supplied to the main control system 10. 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, respectively. The laser interferometers 7Y and 8Y are respectively The positions of the reticle stage RST and the measurement stage 5 in the scanning direction are always measured.
[0042]
Note that the side surfaces orthogonal to the reticle stage RST may be mirror-finished, and these mirror surfaces may be regarded as the movable mirrors 24X and 24Y. The side surfaces orthogonal to the measurement stage 5 are mirror-finished, and these mirror surfaces are The movable mirrors 25X and 25Y may be considered.
Further, in this example, as shown in FIG. 1, the amount of misalignment between the alignment mark (reticle mark) formed on the reticle R and the reference mark (not shown) on the corresponding wafer stage above the reticle R. A pair of reticle alignment microscopes RA and RB are arranged for detecting. A straight line passing through the detection centers of the reticle alignment microscopes RA and RB is parallel to the X axis, and the center of these detection centers coincides with the optical axis AX. In this example, using the reticle alignment microscopes RA and RB corresponding to the second measurement system (absolute value measurement system) of the present invention, the reference marks MC1 and MC2 on the reticle stage RST shown in FIG. The positions of the upper reference marks MD1, MD2 are detected.
[0043]
When the imaging stage is measured, when 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 substantially covers the illumination area 9, the laser interferometers 7X1 and 7X2 Laser beam deviates from the side surface of the reticle stage RST and is irradiated onto the + X direction movable mirror 25X of the measurement stage 5. At this time, the reticle alignment microscopes RA and RB respectively detect the amount of displacement from the detection center (field center) of the reference marks MD1 and MD2 on the reference plate 6, and the main control system 10 in FIG. , MD2 are positioned so that the centers of MD2 are symmetrical with respect to the corresponding detection centers and the amount of displacement is minimized. In this state, the measurement values of the X-axis laser interferometers 7X1 and 7X2 are reset. In addition, you may preset those measured values to a predetermined value, for example.
[0044]
Thereafter, the laser interferometers 7X1 and 7X2 measure the position of the measurement stage 5 in the X direction and the rotation angle with high reproducibility, and the position of the measurement stage 5 in the Y direction is determined by the laser interferometer. It is always measured with high accuracy by 8Y. Therefore, based on these measurement values, the main control system 10 can control the position of the measurement stage 5 with high accuracy via a linear motor or the like. Instead of minimizing the positional deviation amounts of the reference marks MD1 and MD2 as described above, the measurement values of the laser interferometers 7X1 and 7X2 are preset to corresponding values based on the positional deviation amounts. May be.
[0045]
On the other hand, during measurement, the position of reticle stage RST in the non-scanning direction is not measured. However, if reticle stage RST reaches under illumination area 9 for exposure, the laser beam from laser interferometers 7X1 and 7X2 is again emitted from the reticle. The moving mirror 24X of the stage RST is irradiated. Then, as in the case of the measurement stage 5, the positional deviation amounts of the reference marks MC 1 and MC 2 on the reticle stage RST are detected using the reticle alignment microscopes RA and RB, and the main control system 10 detects the positional deviation amounts. In a state where the reticle stage RST is positioned so as to be symmetrical and the smallest, the measurement values of the laser interferometers 7X1 and 7X2 are preset to predetermined values. Thereafter, the position of the reticle stage RST in the X direction and the rotation angle 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 inconvenience that the laser beams from the laser interferometers 7X1 and 7X2 are interrupted.
[0046]
Returning to FIG. 1, wafer W is held on wafer stage WST via a wafer holder (not shown), and wafer stage WST is placed on surface plate 13 movably in the X and Y directions via air bearings. Yes. Wafer stage WST also incorporates a focus / leveling mechanism for controlling the position (focus position) and tilt angle of wafer W in the Z direction. Further, on the surface plate 13, a measurement stage 14 provided with various measurement devices is mounted separately from wafer stage WST via an air bearing so as to be movable in the X direction and the Y direction. The measurement stage 14 also incorporates a mechanism for controlling the focus position on the upper surface.
[0047]
FIG. 2 is a plan view showing wafer stage WST and measurement stage 14. In FIG. 2, a coil array is embedded in the surface of surface plate 13 in a predetermined arrangement, for example, and the bottom surface of wafer stage WST. A magnet array is embedded in the bottom surface of the measurement stage 14 together with the yoke, and a planar motor is constituted by the coil array and the corresponding magnet array, respectively. The planar motor is used to form the wafer stage WST and the measurement stage 14. The position in the X direction, the Y direction, and the rotation angle are controlled independently of each other. The flat motor is disclosed in more detail in, for example, Japanese Patent Application Laid-Open No. 8-51756.
[0048]
Wafer stage WST of this example has only the minimum functions necessary for exposure. That is, wafer stage WST includes a focus / leveling machine, and a wafer holder (bottom side of wafer W) for attracting and holding wafer W and reference mark MA for measuring the position of wafer stage WST are mounted on wafer stage WST. The formed reference mark plate 17A is installed. A reference mark (not shown) for reticle alignment is also formed on the reference mark plate 17A.
[0049]
Further, as shown in FIG. 1, an off-axis type image processing type wafer alignment sensor 16 for wafer W alignment is provided adjacent to the projection optical system PL, and a detection signal of the wafer alignment sensor 16 is received. It is supplied to the 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, the position of the reference mark MA and the like on the wafer stage WST is detected using the wafer alignment sensor 16. That is, the wafer alignment sensor 16 corresponds to the second measurement system (absolute value measurement system) of the present invention.
[0050]
Further, the surface of measurement stage 14 is set to be substantially the same height as the surface of wafer W on wafer stage WST. In FIG. 2, a measurement stage 14 includes an irradiation amount monitor 18 including a photoelectric sensor for measuring all energy (incident energy) per unit time of exposure light that has passed through the projection optical system PL, projection optics, and the like. Illuminance unevenness sensor 19 composed of a photoelectric sensor for measuring the illuminance distribution in slit-shaped exposure region 12 by system PL, measurement plate 20 on which slits 21X and 21Y for measuring imaging characteristics are formed, and a position reference The reference mark plate 17B on which the reference mark MB is formed is fixed. The positional relationship between the reference mark MB and the illuminance unevenness sensor 19 or the like is measured in advance with high accuracy 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.
[0051]
A condenser lens and a photoelectric sensor are arranged on the bottom surface side of the X-axis slit 21X and the Y-axis slit 21Y of the measurement plate 20, respectively, and an aerial image detection system is configured by the measurement plate 20, the photoelectric sensor, and the like. Yes. Instead of the slits 21X and 21Y, an edge of a rectangular opening may be used. The light receiving surface of the dose monitor 18 is formed to have a size that covers the exposure region 12, and the light receiving portion of the illuminance unevenness sensor 19 has a pinhole shape. The detection signal is supplied to the main control system 10 of FIG.
[0052]
Further, the detection signal of the photoelectric sensor at the bottom of the measurement plate 20 is supplied to the imaging characteristic calculation system 11 of FIG. In this case, at the time of 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. 3 is moved to the illumination region 9, and the index mark IM formed on the reference plate 6 is changed. The image is projected on the wafer stage side, and the detection signal from the photoelectric sensor at the bottom is captured by the imaging characteristic calculation system 11 while scanning the image in the X direction and Y direction by the slits 21X and 21Y on the measurement plate 20, respectively. . The imaging characteristic calculation system 11 processes the detection signal to detect the position and contrast of the image of the index mark IM. Based on the detection result, the image surface curvature, distortion, best focus position, and the like are determined. Image characteristics are obtained 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 imaging characteristics such as a predetermined distortion is also provided, and the main control system 10 passes through this correction mechanism. The imaging characteristic of the projection optical system PL can be corrected.
[0053]
In FIG. 2, a sensor such as a dose monitor 18, an illuminance unevenness sensor 19, and a photoelectric sensor at the bottom of the measurement plate 20 provided in the measurement stage 14 all have a heat source such as an amplifier, a power source and a communication. A signal cable is connected. Therefore, when these sensors are mounted on the wafer stage WST for exposure, the positioning accuracy and the like may deteriorate due to the heat source accompanying the sensors and the tension of the signal cable. In addition, thermal energy due to exposure light exposure during measurement of imaging characteristics and the like may also cause deterioration in positioning accuracy. In contrast, in this example, since these sensors are provided on the measurement stage 14 separated from the wafer stage WST for exposure, the wafer stage WST can be reduced in size and weight, and the sensor for measurement can be reduced. There is an advantage that a decrease in positioning accuracy due to the heat energy of the heat source and exposure light during measurement can be prevented. Further, the downsizing of wafer stage WST improves the moving speed and controllability of wafer stage WST, increases the exposure process throughput, and further improves the positioning accuracy and the like.
[0054]
Further, a laser beam is irradiated from the laser interferometer 15Y installed in the + Y direction to the surface plate 13 to the movable mirror 22Y on the side surface in the + Y direction of the wafer stage WST, and biaxial laser interference installed in the −X direction. The laser beam is irradiated from the total 15X1, 15X2 to the movable mirror 22X on the side surface in the −X direction of the wafer stage WST, and the X coordinate, the Y coordinate, and the rotation angle of the wafer stage WST are measured by the laser interferometers 15Y, 15X1, 15X2. The measured values are supplied to the main control system 10 of FIG. 1, and the main control system 10 controls the speed and position of the wafer stage WST via the 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 moving mirrors 22X and 22Y. Similarly, the mirror surfaces on the side surfaces of measurement stage 14 may be regarded as moving mirrors 23X and 23Y. Good.
[0055]
When measuring the incident energy of the exposure light or the like, the laser beams for position measurement are applied to the movable mirrors 23X and 23Y of the measurement stage 14.
FIG. 4 shows an example of the arrangement of wafer stage WST and measurement stage 14 during measurement of the incident energy of exposure light, and the like, by exposing wafer stage WST to a position away from exposure area 12 in this way. When the measurement stage 14 is moved so as to cover the region 12, the laser beams from the laser interferometers 15X1, 15X2, and 15Y come off the movable mirrors 22X and 22Y of the wafer stage WST, and the movable mirrors 23X and 23Y of the measurement stage 14 are moved. Will be irradiated. At this time, the measurement stage 14 is moved so that the reference mark MB on the measurement stage 14 is within the field of view 16a of the wafer alignment sensor 16 of FIG. 1, and the two-axis X-axis laser interferometer 15X1 is moved. , 15X2 with the rotation angle of the measurement stage 14 controlled so that the measurement values of the measurement mark 14 are the same, the amount of positional deviation from the detection center of the reference mark MB is detected. Then, the main control system 10 presets the X component and the Y component of this positional deviation amount to the measured values of the laser interferometers 15X1 and 15X2 and the laser interferometer 15Y, respectively. Thereafter, the position of the measurement stage 14 is measured with high accuracy in a reproducible state by the laser interferometers 15X1, 15X2, and 15Y, and the main control system 10 performs measurement via the planar motor based on the measured values. The position of the stage 14 can be controlled with high accuracy.
[0056]
On the other hand, at the time of exposure, as shown in FIG. 2, the measurement stage 14 is retracted so that the laser mirrors 15X1, 15X2, and 15Y are irradiated with the movable mirrors 22X and 22Y of the wafer stage WST. The reference mark MA is moved into the field of view 16a of the wafer alignment sensor 16, and the positional deviation amount of the reference mark MA is measured in a state in which the measured values of the laser interferometers 15X1 and 15X2 are made to coincide with each other. Then, the measurement values of the laser interferometers 15X1, 15X2, and 15Y are preset. Thereafter, wafer stage WST is positioned with high accuracy in a reproducible state. Note that the position of wafer stage WST and measurement stage 14 can also be roughly controlled by driving the planar motor in an open loop. Therefore, in a state where the laser beam is not irradiated, main control system 10 has wafer stage WST, And the position of the measurement stage 14 is driven by an open loop method using a planar motor.
[0057]
Returning to FIG. 1, although not shown, an oblique incidence type focus position detection system (AF sensor) for measuring the focus position of the surface of the wafer W is arranged on the side surface of the projection optical system PL, and this detection is performed. Based on the result, the surface of the wafer W during scanning exposure is focused on the image plane of the projection optical system PL.
Next, the operation of the projection exposure apparatus of this example will be described. First, the incident light quantity of the exposure light IL with respect 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, the reticle R for exposure is loaded on the reticle stage RST, and the reticle R moves onto the illumination area of the exposure light IL. To do. Thereafter, as shown in FIG. 4, wafer stage WST is retracted, for example, in the + Y direction on surface plate 13, and measurement stage 14 moves toward exposure area 12 by projection optical system PL. Thereafter, after the measurement values of the laser interferometers 15X1, 15X2, and 15Y are preset as described above, the measurement stage 14 is positioned at a position where the light receiving surface of the dose monitor 18 on the measurement stage 14 covers the exposure region 12. In this state, the amount of exposure light IL is measured via the irradiation amount monitor 18.
[0058]
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. Based on the two measured values, a coefficient for indirectly calculating the amount of light incident on the projection optical system PL from the amount of light monitored in the illumination system 1 is calculated and stored. During this time, wafer W is loaded onto 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, the laser beams from laser interferometers 15Y, 15X1, and 15X2 are not irradiated. Therefore, for example, position control is performed by driving a planar motor in an open loop manner. It has been broken.
[0059]
Then, the measurement stage 14 is retracted from the exposure area 12, the wafer stage WST is moved to a position over the exposure area 12, and the measurement values of the laser interferometers 15Y, 15X1, and 15X2 are preset as described above. Thereafter, the wafer stage WST is moved so that the center of the reticle reference mark (not shown) on the reference mark member 17A on the wafer stage WST is positioned near the optical axis AX (the center of the exposure region 12). . Thereafter, using the reticle alignment microscopes RA and RB, the reticle shown in FIG. 1 is set so that the positional deviation amount between the reticle mark on the reticle R and the corresponding reference mark on the reference mark plate 17A is within a predetermined allowable range. The reticle R is aligned by driving the stage RST. At substantially the same time, the position of another reference mark MA on the reference mark plate 17A is again detected by the wafer alignment sensor 16 in FIG. 1, whereby the distance between the detection center of the sensor and the center of the projection image of the reticle R is detected. (Baseline amount) is accurately detected.
[0060]
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 on the wafer W are obtained. Thereafter, scanning exposure is performed while aligning the shot area to be exposed on the wafer W and the pattern image of the reticle R based on the array coordinates and the above-described baseline amount. At the time of scanning exposure to each shot area on the wafer W, in FIG. 1, the reticle R is in the + Y direction (or -Y direction) via the reticle stage RST with respect to the illumination area 9 (see FIG. 3) of the exposure light IL. In synchronization with scanning at the speed VR, the wafer W is scanned in the −X direction (or + X direction) at the speed β · VR (β is the projection magnification) with respect to the exposure region 12 via the wafer stage WST. The
[0061]
Further, during 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 exposure light IL incident on the projection optical system PL is calculated based on the measured value and a predetermined coefficient, and the imaging characteristics (projection magnification, distortion, etc.) of the projection optical system PL generated by the absorption of the exposure light IL are calculated. ) And the calculation result is supplied to the main control system 10. The main control system 10 corrects its imaging characteristics by driving a predetermined lens in the projection optical system PL, for example.
[0062]
The above is the normal exposure, but when the apparatus state is measured for maintenance of the projection exposure apparatus of this example, the measurement stage 14 is moved to the exposure region 12 side to perform the measurement. For example, when measuring the illuminance uniformity in the exposure region 12, after removing the reticle R from the reticle stage RST, the illuminance unevenness sensor 19 is finely moved in the X and Y directions in the exposure region 12 in FIG. Measure the illuminance distribution.
[0063]
Next, an operation for measuring the imaging 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 measurement stage 5 is also irradiated with a laser beam from the laser interferometers 7X1 and 7X2 in the non-scanning direction, and the measurement values are reset (or as described above) using the reticle alignment microscopes RA and RB. Preset). Thereafter, the measurement stage 5 is positioned with high accuracy based on the measurement values of the laser interferometers 7X1, 7X2, and 8Y.
[0064]
At this time, as already described, images of a plurality of index marks IM are projected on the wafer stage side via the projection optical system PL. In this state, in FIG. 4, the measurement stage 14 is driven, the image of the index mark IM is scanned in the X direction and the Y direction by the slit on the measurement plate 20, and the photoelectric sensor at the bottom of the measurement plate 20 is detected. By processing the signals by the imaging characteristic calculation system 11, the position and contrast of those images are obtained. Further, the position and contrast of the images are obtained while changing the focus position of the measurement plate 20 by a predetermined amount. From these measurement results, the imaging characteristic calculation system 11 obtains a variation amount of imaging characteristics such as the best focus position, curvature of field, distortion (including magnification error) of the projection 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.
[0065]
As described above, in the projection exposure apparatus of this example, the positions of the reference marks MA and MB are detected by the wafer alignment sensor 16, and the laser interferometers 15X1, 15X2, and 15Y are preset based on the position information. Laser interferometers 15X1, 15X2, and 15Y can measure and control the position of wafer stage WST or measurement stage 14 with high reproducibility and high accuracy. Similarly, the positions of the reference marks MC1, MC2 or MD1, MD2 are detected by the reticle alignment microscopes RA, RB, and the laser interferometers 7X1, 7X2 are reset, so that the reticle stage RST or the measurement stage 5 is detected. The position can be measured and controlled with high reproducibility and high accuracy.
[0066]
Next, a second embodiment of the present invention will be described with reference to FIGS. In this example, 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 this example. In FIG. 5, the projection exposure apparatus of this example holds wafers W1 and W2 each having a base board 86 as a sensitive substrate and independently 2 Stage device including wafer stages WST1 and WST2 as a plurality of movable stages moving in the dimension direction, projection optical system PL1 disposed above the stage device, reticle R1 or R2 as a mask above projection optical system PL1 A reticle driving mechanism that drives (see FIG. 6) in a predetermined scanning direction, an illumination system that illuminates reticles R1 and R2 from above, and a control system that controls these units are provided. In the following description, the Z axis is taken in parallel to the optical axis AX1 of the projection optical system PL1, the X axis is taken in parallel to the paper surface of FIG. 5 within the plane perpendicular to the Z axis, and the Y axis is taken perpendicular to the paper surface of FIG. To do. In this example, the direction parallel to the Y axis (Y direction) is the scanning direction.
[0067]
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 direction and the Y direction, and these wafer stages WST1, WST1, and WST1, respectively. A wafer stage drive system 81W for driving WST2 and an interferometer system for measuring the positions of wafer stages WST1 and WST2 are provided.
[0068]
More specifically, air pads (not shown) (for example, vacuum preload type air bearings) are provided at a plurality of locations on the bottom surfaces of wafer stages WST1 and WST2, and the air ejection force and the vacuum preload between the air pads are reduced. For example, the wafer stages WST1 and WST2 are levitated and supported on the base board 86 while maintaining an interval of, for example, several μm due to the balance.
[0069]
FIG. 7 shows a drive mechanism for wafer stages WST1 and WST2. In FIG. 7, two X-axis linear guides 95A and 95B extending in the X direction are provided in parallel on base board 86. A set of permanent magnets for the linear motor is fixed along the X-axis linear guides 95A and 95B, respectively, and two moving members 93A and 93C and movably along the X-axis linear guides 95A and 95B, respectively. Two moving members 93B and 93D are attached. Drive coils (not shown) are respectively attached to the bottom surfaces of these four moving members 93A to 93D so as to surround the X-axis linear guide 95A or 95B from above and from the sides. A moving coil type linear motor that drives each of the moving members 93A to 93D in the X direction is configured by the guide 95A or 95B. Therefore, in the following description, for the sake of convenience, these moving members 93A to 93D are referred to as “X-axis linear motors”.
[0070]
Two of the X-axis linear motors 93A and 93B are provided at both ends of the Y-axis linear guide 94A extending in the Y direction, and the remaining two X-axis linear motors 93C and 93D are also the Y-axis linear guide 94B extending in the Y direction. It is fixed at both ends. A set of drive coils for the linear motor is fixed to the Y-axis linear guides 94A and 94B along the Y direction. Therefore, the Y-axis linear guide 94A is driven in the X direction along the X-axis linear guides 95A and 95B by the X-axis linear motors 93A and 93B, and the Y-axis linear guide 94B is driven by the X-axis linear motors 93C and 93D. It is driven in the X direction along the linear guides 95A and 95B.
[0071]
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 the wafer is formed by this permanent magnet and Y-axis linear guide 94A. A moving magnet type linear motor is configured to drive the stage WST1 in the Y direction. Similarly, a moving magnet type linear motor for driving 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.
[0072]
That is, in this example, the wafer stage is constituted by the X-axis linear guides 95A and 95B, the X-axis linear motors 93A to 93D, the Y-axis linear guides 94A and 94B, the permanent magnets (not shown) at the bottom of the wafer stages WST1 and WST2, and the like. A stage system is configured to drive WST1 and WST2 independently two-dimensionally on the XY plane. Wafer stages WST1 and WST2 are controlled by stage controller 38 via stage drive system 81W in FIG. The operation of the stage controller 38 is controlled by the main controller 90.
[0073]
Note that slight yawing can be generated or removed from wafer stage WST1 by slightly changing the thrust balance of the pair of X-axis linear motors 93A and 93B provided at both ends of Y-axis linear guide 94A. It is. Similarly, by slightly changing the balance of the thrusts of the pair of X-axis linear motors 93C and 93D, slight yawing can be generated or removed from wafer stage WST2. On these wafer stages WST1, WST2, wafers W1, W2 are respectively fixed by vacuum suction or the like via a wafer holder (not shown). The wafer holder is finely driven in the Z direction and θ direction (rotation direction around the Z axis) by a Z / θ drive mechanism (not shown).
[0074]
Further, the −X direction and + Y direction side surfaces of wafer stage WST1 are reflecting surfaces 84X and 84Y (see FIG. 6) that are mirror-finished, and similarly, the + X direction and + Y direction side surfaces of wafer stage WST2 Are reflective surfaces 85X and 85Y that have been mirror-finished. These reflecting surfaces correspond to movable mirrors, and measurement beams 92X2, 92X5, 92Y1 to 92Y made of laser beams are projected on these reflecting surfaces from laser interferometers that constitute an interferometer system described later. By receiving the reflected light with each laser interferometer, displacement from the reference surface of each reflecting surface (generally, a reference mirror is arranged on the side surface of the projection optical system or the alignment optical system and used as the reference surface). Thus, the two-dimensional positions of wafer stages WST1 and WST2 are respectively measured. The configuration of the interferometer system will be described in detail later.
[0075]
In FIG. 5, as the projection optical system PL1, a refracting optical system composed of a plurality of lens elements having a common optical axis in the Z direction and having a predetermined reduction magnification, eg, 1/5, is telecentric on both sides. . 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, off-axis type alignment systems 88A and 88B having the same functions are disposed on the optical axis of the projection optical system PL1. They are installed at the same distance from AX1 (which coincides with the center of the projected image of the reticle pattern). These alignment systems 88A and 88B are an LSA (Laser Step Alignment) system using a slit-shaped laser beam, an FIA (Field Image Alignment) system using an image processing system, for example, an LIA (detecting diffracted light of two heterodyne beams). Laser Interferometric Alignment) 3 types of alignment sensors are provided, and the position of the reference mark on the reference mark plate and the alignment mark on the wafer in the two-dimensional direction (X direction and Y direction) can be measured. In this example, these three types of alignment sensors are properly used according to the purpose, so-called search alignment in which the position of three one-dimensional marks on the wafer is detected to measure the approximate position of the wafer, Fine alignment is performed to accurately measure the position of the shot area.
[0076]
In this case, one alignment system 88A is used for measuring the position of the alignment mark on wafer W1 held on wafer stage WST1. The other alignment system 88B is used for measuring the position of the alignment mark on wafer W2 held on wafer stage WST2. Detection signals from the alignment sensors constituting the alignment systems 88A and 88B are supplied to the alignment control device 80. The alignment control device 80 performs A / D (analog / digital) conversion on the supplied detection signals, and performs digital processing. The mark position is detected by calculating the processed waveform signal. This detection result is sent to the main controller 90, and position correction information at the time of exposure is output from the main controller 90 to the stage controller 38 in accordance with the detection result.
[0077]
Although not shown, each of the projection optical system PL1 and alignment systems 88A and 88B has an auto focus / auto for detecting the defocus amount from the best focus position of the exposure surface of the wafer W1 (or W2). A leveling measurement mechanism (hereinafter referred to as “AF / AL system”) is provided. Among them, a so-called oblique incidence type multi-point AF system is used as the AF / AL system of the projection optical system PL1. The alignment systems 88A and 88B are also provided with a similar AF / AL system. That is, in this example, the detection beam can be irradiated to the same measurement area as the AF / AL system used for detecting the defocus amount at the time of exposure by the AF / AL system used during the alignment sequence. ing. For this reason, even during the alignment sequence using the alignment systems 88A and 88B, it is possible to measure the position of the alignment mark with high accuracy with the same focusing accuracy as during exposure. In other words, an offset (error) due to the posture of the stage does not occur between exposure and alignment.
[0078]
Next, the reticle driving mechanism will be described with reference to FIGS. This reticle drive mechanism holds reticle R1 on reticle base board 79 and can move in the two-dimensional direction of the XY plane, and reticle R2 moves in the two-dimensional direction along the same moving plane. It includes a possible reticle stage RST2, a linear motor (not shown) that drives the reticle stages RST1 and RST2, and a reticle interferometer system that manages the positions of the reticle stages RST1 and RST2.
[0079]
More specifically, as shown in FIG. 6, these reticle stages RST1 and RST2 are installed in series in the scanning direction (Y direction), and on the reticle base board 79 via an air bearing (not shown). The reticle stage drive mechanism 81R (see FIG. 5) is configured to perform fine drive in the X direction, fine rotation in the θ direction, and scan drive in the Y direction. 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. For this reason, reticles R1 and R2 on reticle stages RST1 and RST2 are selectively used, for example, in double exposure, and any reticle R1 and R2 can be scanned synchronously with wafers W1 and W2. Yes.
[0080]
On these reticle stages RST1 and RST2, movable mirrors 82A and 82B made of the same material (for example, ceramics) as reticle stage RST1 and RST2 are extended in the Y direction on the side surfaces in the + X direction. Laser interferometers (hereinafter simply referred to as “interferometers”) 83X1 to 83X5 irradiate measurement beams 91X1 to 91X5 composed of laser beams toward the reflecting surfaces in the + X direction of the movable mirrors 82A and 82B. The position of reticle stages RST1 and RST2 in the X direction is 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 actually has two measurement beams separated in the Y direction that can be independently measured for displacement. From these two measurement values, the reticle stages RST1, RST2 The position in the X direction and the yawing amount (rotation angle around the Z axis) can be measured.
[0081]
In this example, the interval between the measurement beams 91X1 to 91X5 in the Y direction is set to be shorter than the width in the Y direction of the movable mirrors 82A and 82B, so that one of the measurement beams 91X1 is always applied to the movable mirrors 82A and 82B. ˜91 × 5 is irradiated. In addition, two adjacent measurement beams (for example, 91X1 and 91X2) are simultaneously irradiated to the same movable mirror (for example, 82B) at a certain time, and the interferometers 83X1 and 83X2 corresponding to this state partially It can be considered that the measurement ranges overlap. 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 will be described later. The measurement values of the interferometers 83X1 to 83X5 are supplied to the stage control device 38 in FIG. 5, and the stage control device 38 corrects the synchronization error with the wafer stages WST1 and WST2 based on these measurement values. Rotation control of reticle stages RST1 and RST2 and position control in the X direction are performed via drive mechanism 81R.
[0082]
On the other hand, in FIG. 6, corner cubes 89 </ b> A and 89 </ b> B as a pair of movable mirrors are installed at the end portion in the −Y direction along the scanning direction of the first reticle stage RST <b> 1. Then, from a pair of double-pass interferometers (not shown), these corner cubes 89A and 89B are each measured with two measurement beams (represented by one measurement beam in FIG. 6). 91Y1 and 91Y2 are irradiated, and relative displacement in the Y direction of reticle stage RST1 is measured with respect to a predetermined reference plane by a pair of interferometers (not shown). In addition, a pair of corner cubes 89C and 89D are also installed at the end of the second reticle stage RST2 in the + Y direction, and measurement is performed on these corner cubes 89C and 89D from the pair of double-pass interferometers 83Y3 and 83Y4. Beams 91Y3 and 91Y4 (actually each composed of two laser beams) are irradiated, and the displacement of reticle stage RST2 in the Y direction is measured by interferometers 83Y3 and 83Y4, respectively.
[0083]
The measurement values of these double-pass interferometers are also supplied to the stage controller 38 of FIG. 5, and the positions of the reticle stages RST1 and RST2 in the Y direction are controlled based on the measurement values. In other words, in this example, an interferometer system for a reticle stage includes interferometers 83X1 to 83X5 having measurement beams 91X1 to 91X5 and two pairs of double-pass interferometers having measurement beams 91Y1 and 91Y2 and measurement beams 91Y3 and 91Y4. Is configured. In FIG. 5, the interferometers 83X1 to 83X5 are represented by the interferometer 83, and the movable mirrors 82A and 82B and the measurement beams 91X1 to 91X5 are represented by the movable mirror 82 and the measurement beam 91X, respectively, in FIG.
[0084]
Next, an interferometer system for managing the positions of wafer stages WST1 and WST2 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 through the center (optical axis AX1) of the projection image of the projection optical system PL1 and the detection centers of the alignment systems 88A and 88B. A measurement beam 92X2 composed of a triaxial laser beam is irradiated from the interferometer 87X2 to the reflection surface 84X on the side surface in the −X direction of the stage WST1. Similarly, a measurement beam 92X5 composed of a triaxial laser beam is irradiated from the interferometer 87X5 to the reflection surface 85X on the side surface in the + X direction of wafer stage WST2. The interferometers 87X2 and 87X5 receive the reflected light to measure the relative displacement in the X direction from the reference position of each reflecting surface.
[0085]
In this case, as shown in FIG. 6, the measurement beams 92X2 and 92X5 are triaxial laser beams capable of measuring displacement independently of each other, and therefore the corresponding interferometers 87X2 and 87X5 are respectively connected to the wafer stage WST1. In addition to measuring the position of WST2 in the X direction, it is possible to measure the tilt angle (rotation angle about the Y axis) and yaw angle (rotation angle about the Z axis) of each stage. In this case, the wafer stages WST1 and WST2 of this example are for performing minute driving in the Z direction, driving of the tilt angle, and rotational driving about the Z axis, respectively, as shown in FIG. Although the Z leveling stages LS1 and LS2 are provided, the Z leveling stages LS1 and LS2 are actually in a portion lower than the reflecting surfaces 84X and 85X. Therefore, the driving amounts for tilt angle control and yawing angle control of wafers W1 and W2 can all be monitored by these interferometers 87X2 and 87X5.
[0086]
The X-axis measurement beams 92X2 and 92X5 are always applied to the reflecting surfaces 84X and 85X of the wafer stages WST1 and WST2 over the entire moving range of the wafer stages WST1 and WST2. Therefore, with respect to the X direction, the position of wafer stages WST1 and WST2 in the X direction is the measurement beams 92X2 and 92X5 regardless of whether exposure is performed using projection optical system PL1 or alignment systems 88A and 88B are used. It is managed based on the measured value using.
[0087]
Further, as shown in FIGS. 6 and 7, the side surfaces in the + Y direction of wafer stages WST1 and WST2 are processed into reflecting surfaces 84Y and 85Y as moving mirrors, and pass through optical axis AX1 of projection optical system PL1 to Y axis. A measurement beam 92Y3 parallel to is radiated from the interferometer 87Y3 to the reflecting surfaces 84Y and 85Y. In addition, interferometers 87Y1 and 87Y5 having measurement beams 92Y1 and 92Y5 passing through the respective detection centers of alignment systems 88A and 88B and parallel to the Y axis are also provided. In the case of this example, the measurement value of the interferometer 87Y3 having the measurement beam 92Y3 is used for the position measurement in the Y direction of the wafer stages WST1 and WST2 at the time of exposure using the projection optical system PL1, and the alignment system 88A or 88B is used. The measured values of the interferometers 87Y1 and 87Y5 are used for measuring the position of the wafer stage WST1 or WST2 in the Y direction during use.
[0088]
Accordingly, the measurement beams of the Y-axis interferometers 87Y1, 87Y3, 87Y5 may deviate from the reflecting surfaces 84Y, 85Y of the wafer stages WST1, WST2 depending on the use conditions. Therefore, in this example, an interferometer 87Y2 having a measurement beam 92Y2 parallel to the Y axis is provided between the interferometers 87X1 and 87Y3, and an interferometer having a measurement beam 92Y4 parallel to the Y axis is provided between the interferometers 87Y3 and 87Y5. By providing 87Y4, the measurement surfaces from at least one interferometer are always irradiated to the reflecting surfaces 84Y and 85Y of wafer stages WST1 and WST2. For this reason, if the width in the X direction of the reflecting surfaces 84Y and 85Y as moving mirrors is DX1, the distance DX2 in the X direction of the measurement beams 92Y1, 92Y2,..., 92Y5 is set to be narrower than the width DX1. As a result, the two adjacent measurement beams in the measurement beams 92Y1 to 92Y5 always irradiate the reflecting surfaces 84Y and 85Y at the same time (having partially overlapping measurement ranges). In the state, the measurement value is 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.
[0089]
Note that the measurement beams 92Y1, 92Y3, and 92Y5 for position measurement in the Y direction are each composed of a biaxial laser beam that can perform position measurement independently in the Z direction, and therefore the corresponding interferometers 87Y1, 87Y3. 87Y5 can also measure the tilt angle (tilt angle) around the X axis in addition to the Y-direction positions of the reflecting surfaces 84Y and 85Y to be measured. In this example, an interferometer system that manages the two-dimensional coordinate positions of wafer stages WST1 and WST2 is configured by a total of seven interferometers 87X2, 87X5, 87Y1 to 87Y5. In this example, as will be described later, while one of the wafer stages WST1 and WST2 is executing an exposure sequence, the other is performing a wafer exchange and wafer alignment sequence. The stage controller 38 controls the position and speed of the wafer stages WST1 and WST2 based on the measurement values of the interferometers so that there is no significant interference.
[0090]
Next, the illumination system and control system of this example will be described with reference to FIG. In FIG. 5, the exposure light source KrF, ArF, or F2Exposure light consisting of pulsed laser light emitted from a light source unit 40 comprising an excimer laser light source and a light reduction system (such as a light reduction plate) passes through a shutter 42 and is then deflected by a mirror 44 to be a beam expander. The beam is shaped into an appropriate beam diameter by 46 and 48 and enters the first fly-eye lens 50. The exposure light emitted from the first fly-eye lens 50 is incident on the second fly-eye lens 58 via the lens 52, the vibrating mirror 54, and the lens 56. The exposure light emitted from the second fly-eye lens 58 passes through the lens 60 and reaches the fixed blind 62 installed at a position conjugate with the reticle R1 (or R2), where the cross-sectional shape is defined in a predetermined shape. Then, the light passes through the movable blind 64 disposed at a position slightly defocused from the conjugate plane with the reticle, passes through the relay lenses 66 and 68, and has a predetermined shape on the reticle R1 as light having a uniform illuminance distribution. Here, a rectangular slit-shaped illumination area IA (see FIG. 6) is illuminated.
[0091]
Next, the control system of this example is composed of an exposure control device 70, a stage control device 38, and the like under the control of the main control device 90, with a main control device 90 controlling the entire device in a centralized manner. ing. For example, when exposing the pattern of the reticle R1 onto the wafer W1, the exposure amount controller 70 instructs the shutter driver 72 to drive the shutter prior to the synchronous scanning of the reticle R1 and the wafer W1 being started. The unit 74 is driven to open the shutter 42.
[0092]
Thereafter, the stage controller 38 starts synchronous scanning (scanning control) between the reticle R1 and the wafer W1, that is, the reticle stage RST1 and the wafer stage WST1, in accordance with an instruction from the main controller 90. This synchronous scanning is performed by the stage controller 38 while monitoring the measurement values of the measurement beams 92Y3 and 92X2 of the interferometer system for the wafer stage and the measurement beams 91Y1, 91Y2 and 91X3 of the interferometer system for the reticle stage. This is performed by controlling the drive system 81W and the reticle stage drive mechanism 81R.
[0093]
When both stages RST1 and WST1 are driven at a constant speed with the projection magnification ratio being within a predetermined synchronization error, the exposure control device 70 instructs the laser control device 76 to start pulse emission. Let As a result, the rectangular illumination area IA (see FIG. 6) of the reticle R1 is illuminated by the exposure light, and the image of the pattern in the illumination area IA is reduced to 1/5 times by the projection optical system PL1, and the surface is exposed to photo Projection exposure is performed on the wafer W1 coated with a resist. As is apparent 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 image of the entire pattern area is obtained by synchronously scanning the reticle R1 and the wafer W1. Are sequentially transferred to the shot area on the wafer. During this exposure, the exposure control device 70 instructs the mirror driving device 78 to drive the vibrating mirror 54, thereby reducing illuminance unevenness due to interference fringes generated by the two fly-eye lenses 50 and 58. .
[0094]
In addition, the reticle R1 and the wafer W1 are prevented from leaking exposure light that has passed through the outside of the pattern area on the reticle R1 (outside the light shielding band) in the vicinity of the edge of each shot area on the wafer W1 during scanning exposure. The movable blind 64 is driven and controlled by the blind control device 39 in synchronism with the scanning with, and a series of these synchronous operations are managed by the stage control device 38. Further, the main controller 90 corrects the stage position with respect to the stage controller 38 that controls movement of each stage, for example, when correcting the approach start position of the reticle stage and wafer stage that perform synchronous scanning during scanning exposure. Indicate the value.
[0095]
Next, as described above, a plurality of interferometers whose measurement ranges partially overlap are arranged on reticle stages RST1 and RST2 and wafer stages WST1 and WST2 in this example, and the measurement values of the interferometers Are sequentially delivered. Hereinafter, taking wafer stage WST2 of FIG. 7 and two Y-axis interferometers 87Y3 and 87Y4 as an example, the interferometer measurement value delivery operation, that is, the interferometer measurement value preset operation will be described with reference to FIGS. This will be described with reference to FIG.
[0096]
First, when wafer stage WST2 in the position of FIG. 7 moves in the −X direction, measurement beam 92Y4 does not enter incident 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 does not enter reflection surface 85Y during this movement. Therefore, measurement values are transferred between the interferometer 87Y4 and the interferometer 87Y3 with high accuracy, and the Y coordinate of the wafer stage WST2 is measured in a reproducible state using either of the interferometers 87Y4 and 87Y3. Need to do. For this reason, in this example, the following measures are taken.
[0097]
FIG. 8A is a plan view showing wafer stage WST2 in FIG. 7. In FIG. 8A, the displacement of wafer stage WST2 in the X direction is changed by X-axis interferometer 87X5, and the wafer stage. The displacement of WST2 in the Y direction is measured by two interferometers 87Y3 and 87Y4. The distance DX2 in the X direction between the measurement beams 92Y3 and 92Y4 of the interferometers 87Y3 and 87Y4 is narrower than the width DX1 in the X direction of the reflecting surface 85Y of the wafer stage WST2.
[0098]
Here, each of the interferometers 87Y4 and 87Y3 of this example is a heterodyne interferometer type laser interferometer, which is a common two-frequency oscillation laser (not shown) having a wavelength of 633 nm, for example, He-Ne as a light source for the measurement beam. Laser light source) is used. 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 heterodyne beams. For example, the reference signal SR having the frequency Δf is generated by photoelectrically converting the interference light branched by about 1/10 and mixed by the analyzer, and the reference signal SR is generated by the phase comparator 26 in each of the interferometers 87Y4 and 87Y3. (See FIG. 9).
[0099]
Further, the first and second heterodyne beams obtained by branching the above heterodyne beam by about 1/10 are supplied to interferometers 87Y3 and 87Y4, and the interferometer 87Y4 performs polarization of the second heterodyne beam. One of the two light beams whose directions are orthogonal to each other is used as a measurement beam 92Y4 and the other is used as a reference beam (not shown), and the reference beam is reflected by a reference mirror (not shown). Then, the interference signal obtained by mixing the reflected reference beam and the measurement beam 92Y4 reflected by the reflecting surface 85Y with the analyzer is photoelectrically converted to generate the measurement signal S2 having the frequency Δf and the phase changing. Is supplied to the phase comparator 26 in FIG. 9, and the phase comparator 26 detects the phase difference φ2 between the reference signal SR and the measurement signal S2 with a predetermined resolution (for example, 2π / 100 (rad)) and integrates it. Is supplied to the container 27.
[0100]
At this time, the wavelength of the measurement beams 92Y3 and 92Y4 is λ, and the reflection surface 85Y is λ / m in the Y direction using an integer m equal to or greater than 1 (m = 2 in the single path method as in this example, In the double-pass method, when m = 4), 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. When the phase difference φ2 crosses 0 in the − direction, 1 is subtracted from the integer N2. During measurement, the integrator 27 sends a measurement value P2 obtained by multiplying {N1 + φ2 / (2π)} by λ / m to the stage controller 38 as an absolute position in the Y direction of wafer stage WST2.
[0101]
Similarly, in the interferometer 87Y3, the phase difference φ1 between the measurement signal S1 obtained from the measurement beam 92Y3 and the reference signal SR, the integer N1 that increases or decreases every time the phase difference φ1 crosses 2π or 0, and λ The measured value P1 calculated from / m is sent to the stage controller 38. That is, interferometers 87Y3 and 87Y4 measure the position of wafer stage WST2 in the Y direction as an absolute position within a width of λ / m.
[0102]
Since the X-axis interferometer 87X5 of this example includes two laser beams separated in the Y direction as shown in FIG. 6, the measurement value of the X coordinate of the reflecting surface 85X by these two laser beams is measured. From the difference, the rotation angle θW2 of wafer stage WST2 can be measured. Therefore, in the “initial state” in which wafer stage WST2 is stopped in advance so that its rotation angle θW2 becomes 0 in the state of FIG. 8A, integers N2 and N1 in interferometers 87Y4 and 87Y3 are reset to 0. 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.
[0103]
In the stage control device 38, the offsets of the measured values of the interferometers 87Y4 and 87Y3 are set to −P20 and −P10, respectively, and thereafter, the offsets (−P20 , −P10) is added as the actual measurement values P2 ′ and P1 ′ of the interferometers 87Y4 and 87Y3. That is, the measured values P2 'and P1' accurately represent the amount of displacement of wafer stage WST2 in the Y direction from the initial state. The initial values (P20, P10) of the measured values are stored.
[0104]
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 measurement beam 92Y4 of the interferometer 87Y4 deviates from the reflecting surface 85Y as a moving mirror. In this state, it is assumed that the Y coordinate of wafer stage WST2 is measured by interferometer 87Y3. From this state, wafer stage WST2 starts moving in the + X direction again toward the position shown in FIG. 8A, and when reflecting surface 85Y enters within the irradiation range (measurement range) of measurement beam 92Y4 of interferometer 87Y4. The measurement value of the interferometer 87Y4 is set (preset) as follows.
[0105]
First, the rotation angle θW2 (substantially close to 0 (rad)) of wafer stage WST2 is measured by measurement beam 92X5 (two laser beams) of X-axis interferometer 87X5. In this state, in FIG. 8A, the Y coordinate measurement value P1 by the interferometer 87Y3 using the measurement beam 92Y3 is obtained. However, the measurement value P1 is a direct measurement value before offset correction is performed. Then, for example, in the stage controller 38, the estimated value of the interference order N2 (N2 is an integer) and the fraction ε2 / (2π) of the interferometer 87Y4 is obtained from the measurement value P1. This fraction ε2 is a value corresponding to the above φ2.
[0106]
That is, the calculation unit in the stage control device 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 measured value P1 of the interferometer 87Y3, and the measured values of the interferometers 87Y4 and 87Y3. From the difference between the initial values (= P20−P10), an estimated value P2 ′ of the measurement value P2 before the offset correction of the interferometer 87Y4 is calculated as follows.
P2 ′ = P1 + DX2 · θW2 + (P20−P10)
[0107]
For example, if the measurement accuracy of the rotation angle measurement value θW2 is high, the estimated value P2 ′ may be preset as the current measurement value P2 of the interferometer 87Y4. However, since the measurement value θW2 may include a certain amount of measurement error, the calculation unit uses the specified value by utilizing the fact that the interferometer 87Y4 can measure the absolute position in units of width λ / m. P2 ′ is decomposed into an integral part and a fractional part. Therefore, the remaining value of N2 times the length λ / m in the estimated value P2 ′ of the measurement value of the interferometer 87Y4 is the fraction ε2 / (2π). That is, the stage control device 38 calculates (estimates) the integer N2 and the fraction ε2 as follows.
[0108]
N2 = g {P2 '/ (λ / m)} (1)
[epsilon] 2 = {P2 '/ ([lambda] / m) -N2} (2 [pi]) (2)
Here, g {X} is a function that gives a maximum integer not exceeding X. As will be described in detail later, the stage controller 38 estimates the interference order and fractional values (N2, ε2) obtained from the measurement value P1, and the phase difference (absolute phase) φ2 actually measured by the interferometer 87Y4. From this, the preset value of the integer (order) N2 of the interferometer 87Y4 is determined.
[0109]
FIG. 9 shows a part of the stage control device 38 of this example and a part of the interferometer 87Y4. As shown in FIG. 9, the interferometer 87Y4 includes, for example, a reference signal SR and a measurement signal output from a laser light source. A phase comparator 26 to which S2 (a photoelectric conversion signal of interference light between the measurement beam and the reference beam) is input is provided. The phase comparator 26 detects the phase difference φ2 between the reference signal SR and the measurement signal S2, 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. It is output. The other interferometers also include a phase comparator 26 and an integrator 27, respectively.
[0110]
At the time of measurement, the accumulator 27 accumulates the integer N2 from the change in the phase difference φ2 as described above, and multiplies {N2 + φ2 / (2π)} by (λ / m) to obtain a measured value P2 obtained by moving the moving mirror. (In this example, the reflection surface 85Y) is output to the stage controller 38 as information indicating the amount of movement. However, when the measurement value is transferred as in the present case, the calculation processing device 28 compares the phase difference φ2 input from the phase comparator 26 with the estimated fraction value ε2 input from the arithmetic unit. . In this comparison, when the estimated value ε2 of the estimated phase difference is 0 (zero) or close to 2π, there is a possibility that the integer N2 indicating the estimated order of interference may be shifted within a range of ± 1. Is something to do for. The comparison operation will be described with reference to FIG. For convenience, in FIG. 10, the estimated value of N2 is the order N.
[0111]
10A to 10C, the horizontal axis represents the phase difference between the reference signal and the measurement signal, and in particular, shows the phase difference in the range of the order of interference k = N−1, k = N, k = N + 1. Show. The phase difference changes by 2π within one order. FIG. 10A shows a case where the absolute value of the difference between the actual phase difference φ2 and the estimated phase difference value ε2 is smaller than π (| φ2−ε2 | <π). In this case, since the actual phase difference φ2 is within the order N as shown in the figure, the order of interference is N as the estimated value, and the order preset value N ′ = N. FIG. 10B 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, as shown in the figure, since the actual phase difference φ2 is within the order N−1, the preset value N ′ is set to N ′ = N−1. FIG. 10C shows a case where 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.
[0112]
The calculation processing device 28 outputs the preset value N ′ obtained as described above as the preset value RE for the integrator 27 in FIG. In the accumulator 27, the preset value RE (that is, N ′) is set as a preset value of an integer N2, and the measured value P2 of the Y coordinate is calculated from the phase difference φ2 from the phase comparator 26 and the integer N ′ as follows. It is calculated and supplied to the stage control device 38, and thereafter the normal measurement operation is performed.
P2 = (λ / m) · N ′ + (λ / m) (φ2 / 2π) (3)
As a result, the measured value P2 of the interferometer 87Y4 is substantially restored to the original value, and the measured value of the interferometer 87Y3 is accurately transferred to the interferometer 87Y4.
[0113]
As described above, in this example, when setting a preset value for the first interferometer in which the reflected light from the mirror surface can be obtained again, the preset value is calculated from the measured values of the other second interferometers. The measured value is used as an estimated value for determining the order of interference (N1 or N2) of the first interferometer, and the estimated order of interference and the phase difference (absolute) measured by the first interferometer Based on (phase) φ, the preset value of the interference order (N1 or N2) of the first interferometer, and hence the preset value of the measurement value of the interferometer, is determined. At this time, since the measurement beam has once deviated from the mirror surface, the interference order N2 or N1 is unknown, but since the interference order is calculated from the measurement values of other interferometers, The preset value can be set with accuracy specific to the interferometer.
[0114]
It should be noted that when the apparatus is started up or when measurement errors are mixed into all measurement values for some reason and it is necessary to reset the measurement values of all interferometers, in FIG. It is necessary to send N2 = 0 and 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 a 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 a value corresponding to the phase difference φ1.
[0115]
Further, the output P2 of the integrator 27 may be fed back to the calculation processing device 18 as necessary. In this case, after the integrator 27 is reset, for example, the amount of wafer stage displacement until the reset value is set in the integrator 27 from the calculation processing device 28 is set in the integrator 27 as a preset value. Can do. In this case, a more accurate 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 accumulator 27. Will be able to do.
[0116]
In this example, when wafer stage WST2 moves, one of the measurement beams from interferometers 87Y3 to 87Y5 needs to be irradiated to side surface 85Y of wafer stage WST2. Therefore, in this example, the interferometer is arranged so that the interval between the measurement beams (for example, the interval DX2 between the measurement beams 92Y3 and 92Y4 shown in FIG. 8) is shorter than the width DX1 of the wafer stage WST2 in the X direction. ing.
[0117]
Further, in the interferometers 83X1 to 83X5 for measuring the positions of the reticle stages RST1 and RST2 in FIG. 6, the initial values (preset values) of the interferometers are set in the same manner, and the measurement values are transferred based on the settings. Is done.
Next, the projection exposure apparatus of this example is provided with first and second transfer systems for exchanging wafers with wafer stages WST1 and WST2, respectively.
[0118]
As shown in FIG. 11, the first transfer system performs wafer exchange with wafer stage WST1 at the left wafer loading position as described later. The first transport system includes a first loading guide 96A extending in the Y-axis direction, first and second sliders 97A and 97C moving along the loading guide 96A, and an unloader attached to the first slider 97A. A first wafer loader configured to include a load arm 98A, a load arm 98C attached to the second slider 97C, and the like, and a first center up composed of three vertical movement members provided on wafer stage WST1 99.
[0119]
The operation of exchanging wafers by the first transfer system will be briefly described. Here, as shown in FIG. 11, a case will be described where wafer W1 'on wafer stage WST1 at the left wafer loading position and wafer W1 transferred by the first wafer loader are exchanged.
First, main controller 90 turns off the vacuum suction of a wafer holder (not shown) on wafer stage WST1 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). As a result, 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 drives center-up 99 down to a predetermined position to deliver wafer W1 'to unload arm 98A, and then starts vacuum suction of unload arm 98A. Next, main controller 90 instructs the wafer loader controller to retract the unload arm 98A and start moving the load arm 98C. As a result, when the unload arm 98A starts moving in the -Y direction in FIG. 11 and the load arm 98C holding the wafer W1 comes above the wafer stage WST1, the wafer loader control device vacuum-sucks the load arm 98C. Is released, and then the center up 99 is driven upward to transfer the wafer W1 onto the wafer stage WST1.
[0120]
In addition, as shown in FIG. 12, the second transfer system that transfers the wafer to and from wafer stage WST2 is symmetrical with the first transfer system, and has a second loading guide 96B and the second loading guide. The sliders 97B and 97D move along 96B, an unload arm 98B attached to the third slider 97B, a load arm 98D attached to the fourth slider 97D, and the like. The load arm 98D holds a wafer W2 'to be exposed next.
[0121]
Next, parallel processing by the two wafer stages WST1 and WST2 of the projection exposure apparatus of this example will be described with reference to FIGS.
In FIG. 11, while the wafer W2 on the wafer stage WST2 is being exposed via the projection optical system PL1, the left stage loading position between the wafer stage WST1 and the first transfer system as described above. The top view of the state in which the exchange of the wafer is performed is shown. In this case, an alignment operation is performed on wafer stage WST1 as described later following the wafer exchange. 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 and 92Y3 of the interferometer system, and the position of wafer stage WST1 where the wafer replacement and alignment operations are performed. The control is performed based on the measurement values of the measurement beams 92X2 and 92Y1 of the interferometer system. For this reason, the main controller 90 in FIG. 5 instructs the stage controller 38 to set initial values (presets) of interferometer measurement values, which will be described later, before performing wafer replacement and alignment operations. .
[0122]
Search alignment is performed following the wafer exchange and initial value setting of the interferometer. The search alignment performed after the wafer exchange is a pre-alignment performed again on wafer stage WST1 because the position error is large only by the pre-alignment performed during transfer of wafer W1. Specifically, the positions of three search alignment marks (not shown) formed on wafer W1 placed on stage WST1 are measured using an LSA sensor or the like of alignment system 88A in FIG. Based on the measurement result, the wafer W1 is aligned in the X direction, the Y direction, and the θ direction. The operation of each part during this search alignment is controlled by main controller 90.
[0123]
After the search alignment is completed, fine alignment is performed in which the arrangement of each shot area on the wafer W1 is obtained by an EGA (enhanced global alignment) method. Specifically, the wafer stage WST1 is sequentially moved based on the design shot arrangement data (alignment mark position data) while managing the position of the wafer stage WST1 by the interferometer system (measurement beams 92X2 and 92Y1). In the meantime, the alignment mark position of a predetermined shot area (sample shot) on the wafer W1 is measured by an FIA sensor or the like of the alignment system 88A in FIG. 5, and the minimum is determined based on this measurement result and the design coordinate data of the shot arrangement. All shot arrangement data is calculated by statistical calculation using the square method. Note that the operation of each part during the EGA fine alignment is controlled by the main controller 90 in FIG. 5, and the above calculation is performed by the main controller 90.
[0124]
Then, while wafer exchange and alignment operations are being performed on wafer stage WST1, the wafer stage WST2 side uses two reticles R1 and R2 to continuously perform step-and-step while changing exposure conditions. Double exposure is performed by a scanning method.
Specifically, fine alignment by the EGA method is performed in advance in the same manner as on the wafer W1 side described above, and shots on the wafer W2 are sequentially formed based on the shot arrangement data on the wafer W2 obtained as a result. After the area is moved below the optical axis of the projection optical system PL1, the reticle stage RST1 (or RST2) of FIG. 6 and the wafer stage WST2 in FIG. Exposure is performed. Such exposure for all the shot areas on the wafer W2 is continuously performed even after reticle replacement. As a specific exposure sequence of 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 to the start position, scanning exposure is performed. At this time, since the exposure conditions (illumination conditions such as annular illumination, modified illumination, and exposure amount) and the transmittance are different between the reticle R2 and the reticle R1, it is necessary to change each condition based on exposure data and the like in advance. There is. The operation of each part during double exposure of the wafer W2 is also controlled by the main controller 90.
[0125]
In the above-described exposure sequence and wafer exchange / alignment sequence performed in parallel on the two wafer stages WST1 and WST2 shown in FIG. 11, the wafer stage that has been completed first is in a waiting state, and both operations are completed. At the time, wafer stages WST1 and WST2 are controlled to move to the positions shown in FIG. Then, wafer W2 on wafer stage WST2 for which the exposure sequence has been completed is exchanged at the right loading position, and wafer W1 on wafer stage WST1 for which the alignment sequence has been completed is subjected to the exposure sequence under projection optical system PL1. Is called. In the right loading position shown in FIG. 12, the wafer exchange operation and the alignment sequence described above are executed as in the left loading position.
[0126]
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 in parallel for the wafers W1 and W2 on each wafer stage. By doing so, throughput is improved. 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 is an operation in which an operation performed on one wafer stage does not affect an operation performed on the other wafer stage. Therefore, in this example, among the operations that are processed in parallel, the operations that do not become disturbance factors are divided into the operations that cause disturbances, or the operations that do not cause disturbances are performed simultaneously. Timing adjustment is achieved.
[0127]
For example, during scanning exposure, since the wafer W1 and the reticles R1 and R2 are synchronously scanned at a constant speed, it is not a disturbance factor and it is necessary to eliminate other disturbance factors as much as possible. For this reason, during scanning exposure on one wafer stage WST1, timing adjustment is performed so as to be stationary in an alignment sequence performed on wafer W2 on the other wafer stage WST2. That is, since the measurement in the alignment sequence is performed in a state where wafer stage WST2 is stationary, it is not a disturbance factor for scanning exposure, and mark measurement can be performed in parallel during scanning exposure. On the other hand, even in the alignment sequence, during scanning exposure, since the motion is constant, it is possible to perform high-precision measurement without causing disturbance.
[0128]
The same thing can be considered at the time of wafer exchange. In particular, vibration generated when the wafer is transferred from the load arm to the center up can be a disturbance factor. Therefore, before scanning exposure or during acceleration / deceleration before and after synchronous scanning is performed at a constant speed (disturbance factor) The wafer may be delivered according to the above. These timing adjustments are performed by the main controller 90.
[0129]
Furthermore, in this example, since double exposure is performed using a plurality of reticles, an effect of improving high resolution and DOF (depth of focus) can be obtained. However, in this double exposure method, since the exposure process must be repeated at least twice, when a single wafer stage is used, the exposure time becomes longer and the throughput is significantly reduced. However, by using the projection exposure apparatus including the two wafer stages of this example, the throughput can be greatly improved, and the high resolution and the effect of improving the DOF can be obtained.
[0130]
Note that the scope of application of the present invention is not limited to this, and the present invention can also be suitably applied to exposure by a single exposure method. By using two wafer stages, it is possible to obtain a throughput that is almost twice as high as when a single exposure method is performed using one wafer stage.
In the second embodiment, a measurement stage for measuring the state of exposure light or imaging characteristics may be further provided as in the first embodiment. In this example, the wafer stage is driven by a combination of one-dimensional motors, but it may be driven two-dimensionally by a planar motor as in the first embodiment.
[0131]
The projection exposure apparatus of the present embodiment assembles a reticle stage RST (RST1, RST2) and wafer stage WST (WST1, WST2) made up of a number of mechanical parts, and a projection optical system PL (PL1) composed of a plurality of lenses. ) Optical adjustment and further comprehensive adjustment (electrical adjustment, operation check, etc.).
The projection exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.
[0132]
In the above embodiment, the present invention is applied to the step-and-scan type projection exposure apparatus. However, the present invention is not limited to this, and the step-and-repeat type projection exposure apparatus and the proximity-type projection exposure apparatus. The present invention can also be applied to an exposure apparatus, an exposure apparatus that uses EUV light such as X-rays as an exposure beam, and a charged particle beam exposure apparatus that uses an electron beam (energy beam) as a light source (energy beam). Further, not only the exposure apparatus but also an inspection apparatus using a stage for positioning a wafer or the like, a repair apparatus, or the like may be used.
[0133]
In addition, this invention is not limited to the above-mentioned embodiment, Of course, a various structure can be taken in the range which does not deviate from the summary of this invention.
[0134]
【The invention's effect】
  The present inventionAccordingly, by providing a stage for each individual function or for each of a plurality of predetermined function groups, each stage can be miniaturized and driven at high speed and with high accuracy. In addition, each of the plurality of stages can be moved within a range larger than the measurement range of the first measurement system, and when each stage enters the measurement range of the first measurement system, the first measurement system Therefore, the position of the stage can be measured with high reproducibility and high accuracy.
[0135]
  next,The present inventionAccordingly, the positions of the plurality of stages can be measured with high accuracy with a wide measurement range and high reproducibility. Further, since the stage position can be measured with high accuracy by the first measurement system simply by matching the measurement result of the first measurement system with the measurement result of the second measurement system, the throughput can be improved.
[0137]
  next,The present inventionAccording to the present invention, since the first stage used for the original exposure has only the minimum functions necessary for exposure, the size of the first stage can be minimized. Throughput can be improved by reducing size and weight. On the other hand, the measuring device for measuring the characteristics when transferring the mask pattern, which is not directly required for the exposure, is mounted on another second stage, and therefore the characteristics when transferring the mask pattern. Can also be measured. Further, the positions of the plurality of stages can be measured with high accuracy.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a projection exposure apparatus according to a first embodiment of the present invention.
2 is a plan view showing wafer stage WST and measurement stage 14 in FIG. 1. FIG.
3 is a plan view showing reticle stage RST and measurement stage 5 in FIG. 1. FIG.
FIG. 4 is a plan view for explaining the case of measuring the state of exposure light using the measurement stage 14 in the first embodiment.
FIG. 5 is a schematic block diagram of a projection exposure apparatus according to a second embodiment of the present invention.
6 is a perspective view showing a positional relationship between two wafer stages WST1, WST2, two reticle stages RST1, RST2, projection optical system PL1, and alignment systems 88A, 88B in the embodiment of FIG. 5; .
7 is a plan view showing a configuration of a drive mechanism for the wafer stage of FIG. 5. FIG.
FIG. 8 is a diagram for explaining measurement value setting of an interferometer implemented in a second embodiment of the present invention.
FIG. 9 is a diagram showing 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 the interferometer system according to the second embodiment of the present invention.
FIG. 11 is a plan view showing a state where a wafer exchange / alignment sequence and an exposure sequence are performed using two wafer stages WST1 and WST2.
12 is a view showing a state where the wafer exchange / alignment sequence and the exposure sequence in FIG. 11 are switched.
[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, 15X1,15X2,15Y ... laser interferometer, 10 ... main control system, 11 ... imaging characteristic calculation system, 13 ... surface plate, DESCRIPTION OF SYMBOLS 14 ... Measurement stage, 16 ... Wafer alignment sensor, 26 ... Phase comparator, 27 ... Accumulator, 28 ... Calculation processing device, 38 ... Stage control device, 83X1-83X5, 83Y1-83Y4, 87X2, 87X5, 87Y1-87Y5 ... Interferometer, 88A, 88B ... Alignment system, 90 ... Main controller

Claims (7)

  1. An exposure apparatus that forms a predetermined pattern on a substrate using an exposure beam ,
    A first stage that holds the substrate and is movable in a predetermined area ;
    A second stage that does not hold the substrate and is movable independently of the first stage;
    A measuring device provided on the second stage for measuring the state of the exposure beam ;
    A first measurement system for measuring positional information of the first stage and the second stage ;
    A second measurement system for measuring a relative positional relationship from a predetermined reference position of the first stage and the second stage;
    When the position of the second stage is controlled using the first measurement system, the measurement result obtained by the second measurement system for the second stage is used for the first measurement system. An exposure apparatus comprising: a control device that corrects a measurement value related to the second stage and measures the state of the exposure beam using the measurement device.
  2. 2. The exposure apparatus according to claim 1, wherein when the exposure beam is irradiated on the substrate, the position of the first stage is controlled by the first measurement system.
  3. The exposure apparatus according to claim 1 , further comprising an optical member that projects the pattern onto the substrate, wherein the measurement device measures an imaging characteristic of the optical member .
  4. The exposure apparatus according to any one of claims 1 to 3, further comprising a planar motor that drives the first stage and the second stage, respectively.
  5. 5. The exposure apparatus according to claim 1, wherein the substrate is loaded onto the first stage during measurement of the state of the exposure beam. 6. .
  6. When measuring the state of the exposure beam,
      6. The exposure apparatus according to claim 1, wherein the second stage is position-controlled such that the measurement apparatus is positioned at an irradiation position of the exposure beam.
  7. An exposure method for forming a predetermined pattern on a substrate using an exposure beam ,
    Holding the substrate on a first stage and moving a predetermined area;
    Moving the second stage having a measuring device for measuring the state of the exposure beam without holding the substrate independently of the first stage ;
    Measuring position information of the first stage and the second stage with a first measurement system ;
    Measuring a relative positional relationship from a predetermined reference position of the first stage and the second stage with a second measurement system ;
    Position control of the second stage is performed using the first measurement system, and the second measurement system uses the measurement result obtained by the second measurement system for the second stage. And a step of correcting a measurement value related to the stage and measuring the state of the exposure beam using the measurement apparatus.
JP33978998A 1998-11-30 1998-11-30 Exposure apparatus and exposure method Expired - Fee Related JP4264676B2 (en)

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JP33978998A JP4264676B2 (en) 1998-11-30 1998-11-30 Exposure apparatus and exposure method
EP98961381A EP1041357A4 (en) 1997-12-18 1998-12-17 Stage device and exposure apparatus
KR1020007006488A KR20010033118A (en) 1997-12-18 1998-12-17 Stage device and exposure apparatus
PCT/JP1998/005705 WO1999031462A1 (en) 1997-12-18 1998-12-17 Stage device and exposure apparatus
AU16828/99A AU1682899A (en) 1997-12-18 1998-12-17 Stage device and exposure apparatus
US09/593,800 US6897963B1 (en) 1997-12-18 2000-06-15 Stage device and exposure apparatus

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