JP2002134392A - Apparatus and method for measuring position, aligner and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for measuring positions, capable of obtaining high measuring accuracy without lowering the throughput, to provide an aligner capable of accurately superposing and to further provide a method for manufacturing a device using the aligner. SOLUTION: The apparatus for measuring the position comprises at least four plate alignment sensors 20a to 20d, provided corresponding to first to forth quadrants R1 to R4 partitioned by a straight line L1, extending in the X-axis direction and a straight line L2, extending in the Y-axis direction through a center of a plate P to measure positional information of corresponding marks AM1 to AM4 based on lights obtained by illuminating the corresponding marks AM1 to AM4. with a detection light. The apparatus simultaneously measures the positional information of the X-axis direction and the Y-axis direction of the marks AM1 to AM4 formed in the first to fourth quadrants R1 to R4, by using four plate alignment sensors 20a to 20d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring device and method, an exposure device, and a device manufacturing method, and particularly to a micro device such as a semiconductor device, an image pickup device, a liquid crystal display device, or a thin film magnetic head in a lithography process. Position measuring apparatus and method used in manufacturing, exposure apparatus,
And a device manufacturing method.

[0002]

2. Description of the Related Art Semiconductor devices, imaging devices, liquid crystal display devices,
Alternatively, in the manufacture of a micro device such as a thin film magnetic head, an image of a pattern formed on a mask or a reticle (hereinafter, referred to as a mask) is referred to as a wafer or a glass plate (hereinafter, these are collectively referred to as a substrate). An exposure device for transferring the image to the substrate is used. For example, a liquid crystal display element (LC
When manufacturing D), a so-called step-and-repeat type exposure apparatus (hereinafter, referred to as a stepper) is often used. This stepper exposes a pattern of an LCD formed on a mask to a predetermined area of a glass plate (hereinafter, referred to as a plate) as a substrate, and then steps the stage on which the plate is mounted by a predetermined distance. Then, by exposing another area of the plate again and repeating this operation for all the areas set on the plate, an apparatus for transferring the image of the pattern formed on the mask to the entire plate. is there.

When transferring an image of a pattern formed on a mask onto a plate, it is necessary to precisely match the position of the plate with the position of the image of the pattern. In recent years, with the miniaturization of the pattern formed on the plate, high alignment accuracy between the mask and the plate has been required. Alignment accuracy is required. For this reason, marks for position measurement are formed on the mask and the plate, and the exposure apparatus includes a position measurement device that measures the position information of these marks with high accuracy.

A major type of position measuring device that measures position information using position measuring marks formed on a plate is classified into LSA (Lase) from the viewpoint of measurement principle.
r Step Alignment (FIA) method or FIA (Field Image Alignment)
ent) method. The LSA type position measurement device is a position measurement device that irradiates a laser beam onto a mark of a dot row formed on a plate and measures position information of the mark by using diffracted / scattered light. An FIA type position measuring device illuminates a mark using a light source having a wide wavelength band such as a halogen lamp, converts an image of the obtained mark into an image signal, and performs image processing to obtain position information of the mark. Is a position measuring device for determining the asymmetric mark formed on the aluminum layer or the plate.

[0005] The above-described position measuring apparatus of the LSA system needs to irradiate a laser beam to a dot row mark, and therefore needs to have an optical system for shaping a laser beam emitted from a laser light source into an elongated rectangular shape. . Further, in order to measure the position information of the mark, it is necessary to scan the mark formed on the substrate to be measured with the irradiated laser light, so that the stage must be moved. Normally, an orthogonal coordinate system (XY) set for the stage
Since it is necessary to measure the position information of the mark in the rectangular coordinate system), it is necessary to scan the stage by moving the stage in the X-axis direction and the Y-axis direction. On the other hand, since the FIA type position measuring device uses a light source having a wide wavelength bandwidth such as a halogen lamp as described above, it has an advantage that the influence of resist interference can be reduced. Further, since the image of the mark is captured using an image sensor such as a CCD (Charge Coupled Device) and the obtained image signal is subjected to image processing to obtain the position information of the mark, the position information of the LSA method is obtained. Unlike the measuring device, it is not necessary to move the stage when measuring the position information of the mark, and the measurement is performed while the stage is stationary.

When the position measuring devices are classified from the viewpoint of an observation method in position measurement, a TTL (through-the-lens) for measuring position information of a mark on a plate via a projection optical system is used.
The lens) system, a TTM (through-the-lens) system that simultaneously observes a mark formed on a plate and a mark formed on a mask via a projection optical system and detects a relative positional relationship between the two.
The mask) system, and an off-axis system that directly measures position information of a mark on a plate without using a projection optical system. In the manufacture of a liquid crystal display element, an off-axis type position measuring device is generally used to handle a large plate. An exposure apparatus used when manufacturing a liquid crystal display element is usually used for the following reasons.
An off-axis type LSA type position measuring device is provided.

[0007] As described above, the LSA type position measuring device measures the position information of a mark by moving the stage while irradiating the mark with laser light and scanning the mark to be measured with the laser light. However, when measuring the position information of the mark, even if the mark is arranged with a large deviation from the position irradiated with the laser beam, the position information of the mark is measured by increasing the moving distance of the stage. be able to. On the other hand, in the FIA type position measurement device, since the image of the mark is captured by the image sensor, it is difficult to widen the measurement field of view while maintaining the measurement accuracy. Therefore, when measuring the position information of the mark, if the mark to be measured is placed at a position out of the measurement visual field,
Mark position information cannot be measured.

In order to solve this problem, the magnification of the optical system is set to be high, the field of view is set to be narrow, and the magnification of the optical system is set to be low, and the magnification of the optical system is set to be low.
A FIA type position measurement device including a low magnification system in which a measurement field of view is set wide at the expense of measurement error has also been put to practical use. When measuring the position information of a mark using this position measuring device, first, the rough position of the mark is measured using a low magnification system, and based on the measurement result, the mark is aligned with the position measuring device, and the high magnification is measured. Switch to the system and measure the position information of the mark with high accuracy. As described above, in the position measuring device including the low-magnification system and the high-magnification system, it is possible to solve the problem that the position information of the mark cannot be measured even when the mark is arranged outside the measurement field of view of the high-magnification system. However, in order to provide a high magnification system and a low magnification system,
There is a problem that the configuration becomes complicated and the cost increases.

Further, since a large plate is used in the liquid crystal display element, the plate surface may be undulated, or the plate surface and the back surface may not be formed parallel (tapered). In order to measure the position information of a plurality of marks formed on a plate having such characteristics with high accuracy using an off-axis type position measuring device, the position information must be within the depth of focus of the optical system provided in the position measuring device. It is necessary to control so that the mark of is arranged. On the other hand, LS
The A-type alignment sensor measures position information using light (diffraction / scattered light) obtained by irradiating a mark with laser light, and therefore has a substantial depth of focus.
The measurement can be performed with respect to the IA type position measurement device almost without considering the position deviation of the mark in the direction orthogonal to the plate surface. For the reasons explained above, the conventional stepper is of the off-axis type and has
An SA type position measurement device is provided.

In an exposure apparatus equipped with an off-axis position measuring device, a measurement field of view is set outside a projection area of a projection optical system that irradiates a plate with an image of a pattern formed on a mask. The measurement center of the measurement device and the center of the projected image of the pattern formed on the mask (center of exposure)
It is necessary to obtain a baseline amount, which is an interval between the two, in advance. The measurement of the baseline amount is performed using a reference mark provided on a stage on which the plate is placed.

Conventionally, when measuring the baseline amount, first, the stage is moved to dispose the reference mark at a predetermined position in the projection area of the projection optical system, and the reference mark is formed on the reference mark and the mask via the projection optical system. The center of the projected image of the pattern formed on the mask (exposure center) is obtained by simultaneously observing the position measurement marks. Next, the stage is moved to dispose the reference mark within the measurement field of view of the position measurement device, and the position measurement device measures the position information of the reference mark to determine the measurement center of the position measurement device. Then, the distance between the exposure center and the measurement center is obtained based on the obtained exposure center and measurement center, and the stage position when the exposure center and the measurement center are obtained, thereby obtaining the baseline amount. In an exposure apparatus equipped with an LSA type position measurement device, it is necessary to scan the reference mark with laser light to measure the position information of the reference mark even when obtaining the baseline amount.

When performing the exposure process, after the plate is conveyed on the stage, the mark formed on the plate is measured by the position measuring device, the deviation amount of the mark from the measurement center is obtained, and this deviation amount is used as a base. After the plate is moved by the distance corrected by the line amount, the relative position between the plate and the mask is accurately aligned, and then the mask is irradiated with exposure light to expose the image of the pattern formed on the mask via the projection optical system. Transfer to plate.

In recent years, the size of a plate for performing exposure processing has been increased. From the viewpoint of suppressing an increase in cost required for exposure processing and preventing a decrease in accuracy, it is necessary to minimize the size of the stage. For this reason, a reference mark that moves up and down is provided at the position where the plate is placed, and the baseline amount is measured using the reference mark that moves up and down. Also, with the increase in the size of the plate, an exposure apparatus that exposes the entire plate using a plurality of masks has been used. For example, 4
When a single mask is used, the reference mark is moved upward in a state where the plate is not placed on the stage, and the reference pattern is moved approximately to the plate surface position when the plate is placed on the stage. It is necessary to dispose them at the same position and measure the exposure center for each mask in order to determine the base line amount for each mask.

A method for measuring the positional information of each mask is described in Japanese Patent Application Laid-Open No. Sho 61-143760, for example, by using a reference mark provided on a stage and a light receiving sensor provided below the reference mark. The relative position between the formed position detection mark and the reference mark is detected, and the slit mark formed as the reference mark is emitted from below (stage side) and projected as in JP-A-63-284814. There is a method of detecting a relative position with respect to a slit mark formed on a mask via an optical system by a light receiving sensor provided in the illumination optical system.

[0015]

In recent years, in the production of liquid crystal display devices, TFTs formed in liquid crystal display devices are formed by forming finer patterns.
(Response) of elements such as (Thin Film Transistor) and the density of pixels per unit area have been improved. Conventionally, liquid crystal display elements have often been manufactured according to a process rule of 3 μm, but recently, 2 μm
It is being manufactured with the following process rules. In order to cope with such a situation, it is necessary to improve the resolution in an exposure apparatus used for manufacturing a liquid crystal display element.

Now, let us consider a case where the resolving power is improved by a factor of 1.5 while the exposure area that can be exposed at one time by the exposure apparatus remains the same. When the resolution is improved, the depth of focus of the projection optical system provided in the exposure apparatus necessarily decreases. For example, the resolution of 1.times.
A five-fold improvement reduces the depth of focus to 1 / 2.25. As described above, when the depth of focus is reduced, the plate surface needs to be kept within the depth of focus over the entire surface of the plate, so that the warpage, undulation, and taper of the plate become problems. For this reason, it is necessary to improve the flatness of the plate, and a liquid crystal display device is being manufactured using a plate having a high flatness.

Further, it is necessary to increase the overlay accuracy as the resolution increases. For this purpose, it is necessary to measure the position information of the mark formed on the plate with high accuracy, and it is also necessary to improve the accuracy of the alignment. In the case of a liquid crystal display device, since the exposure area is larger than that in the manufacture of a semiconductor device, improvement in throughput (the number of plates that can be processed in a unit time) has been most important. Therefore, a decrease in throughput must be avoided even when the overlay accuracy is improved.

The conventional exposure apparatus includes the off-axis type LSA type position measuring apparatus as described above. When measuring the position information of a mark with an LSA type position measuring device, it was necessary to move a large stage and scan the mark with laser light. In addition, since it is necessary to scan in two directions, the X-axis direction and the Y-axis direction, it takes time to measure the position information of the mark, which is one of the factors that deteriorates the throughput. Further, as the number of times of measurement of the mark is increased in order to improve the alignment accuracy, the number of times of movement of the large stage is increased, and there is a problem that the throughput is further decreased and the throughput is reduced. Further, the LSA type position measuring apparatus is an apparatus of a type that scans a mark with laser light as described above. Therefore, the detection accuracy largely depends on the measurement accuracy of the laser interference system that measures the position information of the stage.
Therefore, if the fluctuation or vibration of the stage occurs while measuring the position information of the mark, there is a problem that the measurement accuracy is greatly affected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a position measuring apparatus and method capable of obtaining high measurement accuracy without lowering the throughput. It is an object of the present invention to provide an exposure apparatus that can perform the above-described steps, and further provide a method for manufacturing a device using the exposure apparatus.

[0020]

In order to solve the above-mentioned problems, a position measuring apparatus according to the present invention is directed to a straight line (X-axis direction) extending through a central portion of a position detection target (P) and extending in a first direction (X-axis direction). L
1) and each of the first quadrant (R1) to the fourth quadrant (R4) divided by a straight line (L2) extending in a second direction (Y-axis direction) orthogonal to the first direction (X-axis direction). The marks (AM1 to AM4) are provided corresponding to the respective marks (AM1 to AM4), and the corresponding marks (AM1 to AM4) are irradiated with the detection light (IL1).
AM4) at least four sensor units (20a to 20d) for measuring position information, and the marks (AM1 to AM4) formed in each of the first quadrant (R1) to the fourth quadrant (R4).
A control system (15) for simultaneously measuring position information in the first direction (X-axis direction) and the second direction (Y-axis direction) of AM4) using at least the four sensor units (20a to 20d). It is characterized by having. According to the present invention, the marks formed in each of the first to fourth quadrants are irradiated with the detection light almost simultaneously, and the position information of each mark is obtained based on the light obtained by irradiating each of the marks with the detection light. At almost the same time. Therefore, unlike the conventional measurement, when measuring the position information of the mark, the movement of the stage is not involved, so that the position information of the mark can be measured without lowering the throughput. Also, the first quadrant ~
Since the position information of each mark formed in the fourth quadrant is measured, the position information of the mark required to calculate the distortion of the position detection object is uniformly obtained over the entire position detection object. Therefore, the position information of the position detection target can be obtained with high accuracy. Further, in the position measuring device of the present invention, the mark (AM1 to AM4) obtained by irradiating the mark (AM1 to AM4) with the detection light (IL1) by the at least four sensor units (20a to 20d) may be used. AM1 to AM
4) The images (Im1 to Im4) are captured on the imaging surfaces (FP, FP1 to FP1)
FP4) is provided with an image sensor (52) for receiving and imaging an image.
The control system (15) controls the imaging planes (FP, FP1 to FP).
P4) The central measurement area (SC) set including the central part
1, SC2) (AM1 to AM2)
4) based on the image (Im1 to Im4).
M1 to AM4) Each position is measured simultaneously. Further, the position measuring device of the present invention includes a stage (PS) movable with the position detection object (P) mounted thereon, and the control system (15) includes the imaging system (FP, FP1 to FP1). FP4), the images (Im1 to Im4) of the marks (AM1 to AM4) formed in the peripheral measurement areas (W11, W12, W21, W22) set in the peripheral portion.
4), the approximate position information of the marks (AM1 to AM4) is measured, and based on the measurement result, the stage (PS) is moved, and the central measurement area (SC) is moved.
1, SC2). According to these inventions, among the images of the mark included in the light obtained by irradiating the mark with the detection light, based on the image formed on the peripheral measurement area set in the peripheral portion of the imaging surface of the image sensor. The approximate position information of the mark is measured, the position detection target is moved based on the measurement result, and the position of each mark is determined based on the image formed in the central measurement area set including the central part of the imaging surface. Information is obtained almost simultaneously. Therefore, before the position information is measured based on the image formed in the central measurement area, the position of the position detection object is adjusted based on the rough position information of the mark. Even if the mark is displaced from the part, the position information of each mark can be measured at high speed. In addition, since the mark for measuring rough position information and the mark for measuring high-precision position information are the same mark, the number of marks formed on the position detection target can be reduced. Furthermore, there is no need to switch the optical system (for example, switching the magnification) between the case where rough position information is measured and the case where high-precision position information is measured, so that high-speed measurement can be performed. Here, when measuring the approximate position information of the mark, measuring the position information of at least two marks of the marks formed in each of the first to fourth quadrants can prevent a decrease in throughput. This is preferable from the viewpoint of maintaining the measurement accuracy. In the peripheral measurement area, there are two first sensors along the first direction.
A measuring unit (W11, W12) and two second measuring units (W21, W22) along the second direction are set, and one of the first measuring unit and one of the first measuring unit is used for measuring rough position information of the mark. Switching to another first measuring unit or another second measuring unit, or another first measuring unit and another second measuring unit according to the measurement result obtained by using the second measuring unit. Is preferably performed. Further, it is preferable that, prior to the measurement of the position information of each mark, the position detection object is arranged such that each mark is arranged at a position shifted by a predetermined amount with respect to each sensor unit. Further, the exposure apparatus of the present invention includes an exposure light source (2) for emitting exposure light, and irradiates the exposure light onto a mask to convert an image of a pattern formed on the mask (M1 to M4) to a substrate (P). In the exposure apparatus, the substrate (P) is used as the position detection object.
The stage (PS) is moved based on the measurement result of the position measuring device, and the mask (M1-M4) is provided. M4) and positioning means (1) for performing relative positioning between the substrate (P).
5, 16X, 16Y). Further, in the device manufacturing method of the present invention, the substrate (P) is moved to the position detection object (P) by using the above-described position measurement method.
A position measurement step of measuring position information of marks (AM1 to AM4) formed on the substrate; and a relative position between the mask (M1 to M4) and the substrate (P) based on a measurement result in the position measurement step. A positioning step of performing positioning, and a transferring step of irradiating the mask (M1 to M4) with exposure light and transferring an image of a pattern formed on the mask (M1 to M4) onto the substrate (P). And a developing step of developing the transferred substrate.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a position measuring apparatus and method, an exposure apparatus, and a device manufacturing method according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG.
FIG. 1 is a perspective view illustrating an overall configuration of an exposure apparatus according to an embodiment of the present invention including a position measuring device according to an embodiment of the present invention. In the present embodiment, a case where a pattern of a liquid crystal display element is formed as the masks M1 to M4 is used and an image of the pattern is transferred to the plate P by an exposure apparatus of a step-and-repeat method is described as an example. Will be explained. In the following description, X shown in FIG.
An YZ orthogonal coordinate system is set, and the positional relationship of each member will be described with reference to the XYZ orthogonal coordinate system. The XYZ orthogonal coordinate system is set so that the X axis and the Y axis are parallel to the stage PS, and set in a direction orthogonal to the Z axis stage PS (a direction parallel to the optical axis of the projection optical system PL). ing. In the XYZ coordinate system in the figure, the XY plane is actually set as a plane parallel to the horizontal plane, and the Z axis is set vertically upward.

At the first focal position of the elliptical mirror 1, a light source 2 such as an ultra-high pressure mercury lamp for supplying exposure light of g-line (436 nm) and i-line (365 nm) is arranged. Is condensed by the elliptical mirror 1 and reflected by the mirror 3 and then converged to the second focal position of the elliptical mirror 1. Then, the light enters the collector lens 4 and is converted into a parallel light flux. A light-reducing filter 5 is disposed between the mirror 3 and the collector lens 4 so as to be able to advance and retreat with respect to the optical path. The neutral density filter 5 suppresses the amount of exposure light reflected by the mirror 3, and is provided, for example, to adjust the amount of light detected by the photoelectric detector 19b. Although not shown, it is preferable to provide a wavelength selection filter in the optical path between the mirror 3 and the collector lens 4 that allows only the exposure light of a predetermined wavelength to pass.

The exposure light transmitted through the collector lens 4 is converted into a light beam having a uniform illuminance distribution by a fly-eye integrator 6. The fly-eye integrator 6 is composed of a large number of positive lens elements, and forms a light source image having the same number of positive lens elements on its exit side to form a substantial surface light source. Although not shown in FIG. 1, the exit surface of the fly-eye integrator 6 has a σ value for determining the illumination condition (on the pupil plane with respect to the aperture diameter of the pupil of the projection optical system PL described later). The aperture member for setting the ratio of the aperture of the light source image at the point (a) is disposed.

A light beam from a large number of light source images formed by the fly-eye integrator 6 is passed through a half mirror 7 and a lens 8 to increase or decrease the size of an opening S to form a blind 9 for adjusting the irradiation range of exposure light. Irradiate. Exposure light having passed through the opening S of the blind 9 passes through a lens 10 and is reflected by a mirror 11 to enter a condenser lens (not shown).
Is formed on the mask M1 placed on the mask stage MS, and a desired range of the mask M1 is illuminated. The replacement of the mask placed on the mask stage MS is performed by a mask changer (not shown). still,
The elliptical mirror 1, the light source 2, the mirror 3, the collector lens 4, the neutral density filter 5, the fly-eye integrator 6, the half mirror 7, the lens 8, the blind 9, the lens 10, the mirror 11, and the condenser lens (not shown) are illumination optics. Form a system.

The image of the pattern existing in the illumination area of the mask M1 is transferred via a projection optical system PL onto a plate P serving as a position detection object (substrate) mounted on a stage PS. The projection optical system PL is provided with a lens controller (not shown) that controls optical characteristics such as imaging characteristics to be constant in response to environmental changes such as temperature and atmospheric pressure. still,
In FIG. 1, the plate P is indicated by a broken line, which indicates a state when the plate P is mounted on the stage PS. The stage PS includes an XY stage for moving the plate P in the XY plane, a Z stage for moving the plate P in the Z-axis direction, a stage for slightly rotating the plate P in the XY plane, and an XY plane in which the angle with respect to the Z axis is changed. And the like, which adjusts the inclination of the plate P with respect to. At one end of the upper surface of the stage PS, movable mirrors 13X and 13Y having a length longer than the movable range of the stage PS are attached.
The laser interferometer 14 is located at a position facing the mirror surfaces of X and 13Y.
X and 14Y are arranged respectively.

Although the illustration is simplified in FIG. 1, the laser interferometer 14X includes two X-axis laser interferometers for irradiating the movable mirror 13X with a laser beam along the X-axis. One laser interferometer for axis and laser interferometer 14
Based on Y, the X coordinate and the Y coordinate of the stage PS are measured. The rotation angle of the stage PS in the XY plane is measured based on the difference between the measurement values of the two laser interferometers for the X axis. Information on the X coordinate, the Y coordinate, and the rotation angle measured by the laser interferometers 14X and 14Y are supplied to the main control system 15 as stage position information. The main control system 15 outputs the supplied stage position information to the stage drive systems 16X and 16Y while monitoring the stage position information, and controls the positioning operation of the stage PS. Although not shown in FIG. 1, the mask M
The mask stage MS on which the stage 1 is mounted is also provided with a moving mirror and a laser interferometer provided for the stage PS. Is done.

Here, the arrangement of members provided on the stage PS for measuring various kinds of position information will be described. FIG. 2 is a diagram showing the arrangement of members provided on the stage PS used when measuring various types of position information.
As shown in FIG. 2, the stage PS includes a reflector RF0.
And reference marks FM1 and FM2. The reflection plate RF0 and the reference marks FM1 and FM2 are on the stage P
S is configured to be freely protruded and immersed with respect to S, and is designed so that the upper surface thereof is substantially flush with the upper surface of the plate P when protruding above the stage PS. Also, by immersing these in the stage PS, the plate P is moved to the stage PS.
It can be placed on top. Reflector RF0 and fiducial mark FM
The reason why the FM1 and FM2 can be freely projected and immersed is the stage P
This is for reducing the size of S. That is, if these are formed in portions other than the portion where the plate P is placed, the stage PS is correspondingly enlarged. The reflection plate RF0
What kind of position information the reference marks FM1 and FM2 are used for measuring will be described below as needed. In FIG. 2, the plate alignment sensor 2 shown in FIG.
The arrangement relation of 0a to 20d is also illustrated. Stage PS
Is moved, the plate alignment sensors 20a-2a-2
0d, the reflection plate RF0 and the reference marks FM1, FM
2 moves.

Returning to FIG. 1, the position of the stage PS in the Z-axis direction is determined by an autofocus comprising a light projecting system 17a and a light receiving system 17b disposed above the stage PS and beside the projection optical system PL. It is measured by the mechanism 17. The auto-focus mechanism 17 irradiates the detection light emitted from the light projecting system 17a to a reflecting plate RF0 (see FIG. 2) provided on the stage PS from an oblique direction, and reflects the reflected light by a light receiving system 17b. By receiving the light, the upper surface of the plate P is positioned at a position conjugate with the mask M1 placed on the mask stage MS in the optical axis direction (Z-axis direction) of the projection optical system PL. .

On the other hand, the position information of the mask is measured by mask observation systems 18a and 18b provided above the mask. The mask observation systems 18a and 18b measure the position of the position measurement mark by irradiating the position measurement mark drawn outside the pattern area on the mask with detection light and receiving the reflected light. And outputs the measurement result to the main control system 15. Normally, a pattern formed in the pattern area of the mask and a mark for position measurement have a drawing error, and depending on the position of the mask, it is necessary to consider the influence of distortion of the projection optical system PL. Are arranged near the pattern area.

In this embodiment, four masks M1 are used.
To M4, the mask observation system 18a, 18b sets the pattern image formed on each mask on the mask stage MS before transferring the image of the pattern formed on each mask to the plate P. Position information is accurately measured for each mask to be placed. The main control system 15
Based on the measurement results of the mask observation systems 18a and 18b, the mask stage MS holding the mask M1 can be moved to a desired position on the XY plane by servo-controlling a driving unit such as a linear motor (not shown). It is a configuration that can be done. Also, a lens 1 is provided in the illumination optical system.
An alignment system composed of 9a and a photoelectric detector 19b is provided. This alignment system uses the fiducial mark FM
1, a mark for position measurement formed on the mask M using the FM2 is detected by the TTL method.

Further, a photoelectric measuring device is provided on the stage PS. This photoelectric measuring device is a mask stage M
The pattern formed on the mask mounted on the mask stage MS receives an image obtained by irradiating exposure light to a position measurement mark formed on the mask mounted on the mask stage MS. Of the projected image (exposure center). The exposure center measured by the photoelectric measurement device is used when obtaining the baseline amount. FIG. 3 is a cross-sectional view illustrating a configuration of a photoelectric measurement device used when obtaining a baseline amount for the stage PS. As shown in FIG. 3, the photoelectric measurement device includes the reference marks FM1 and FM2, the lens 31, the stop 32, the lens 33, the field stop 34, and the lens 3.
5 and a photoelectric conversion element 36.

The reference marks FM1 and FM2 have slit patterns 30a used for measuring the baseline amount.
And a reference position mark 30b are formed. FIG.
Is a diagram showing an example of a slit pattern 30a and a reference position mark 30b formed on the reference marks FM1 and FM2. Slit pattern 30a and reference position mark 3
Ob is formed, for example, by depositing chromium on a transparent glass substrate. In FIG. 4, a portion where chromium is deposited is hatched. The slit pattern 30a is formed in a shape in which an opening whose longitudinal direction is set in the X-axis direction and an opening whose longitudinal direction is set in the Y-axis direction intersect.

FIG. 5 is an enlarged view of the reference position mark 30b. As shown in FIG. 5, the reference position mark 30b is
U-shaped mark element 37a and U-shaped mark element 3
7b are arranged in the X-axis direction, and U-shaped mark elements 37c and 37d are arranged in the Y-axis direction. Here, the opening 38a of the U-shaped mark element 37a and the U-shaped mark element 37b
The opening 38b of the U-shaped mark element 37c and the opening 38d of the U-shaped mark element 37d are set so as to face in opposite directions. You. Further, the reference position mark 30
b, an L-shaped mark element 39a whose longitudinal direction is set in each of the X-axis direction and the Y-axis direction is arranged adjacent to the U-shaped mark elements 37a and 37c. The element 39b is disposed adjacent to the mark element 37b and the mark element 37c, and the L-shaped mark element 39c
Are disposed adjacent to the mark elements 37b and 37d, and the L-shaped mark element 39d is disposed adjacent to the mark elements 37c and 37d.

Returning to FIG. 3, the slit pattern 30a is
It is used when measuring the center (exposure center) of the projected image of the pattern formed on the mask mounted on the mask stage MS. Therefore, an image of a mark for position measurement formed on the mask mounted on the mask stage MS is projected onto the slit pattern 30a via the projection optical system PL. The light passing through the slit pattern 30a forms an image at the position of the field stop 34 via the lens 31, the stop 32, and the lens 33 in this order. The field stop 34 is provided with reference marks FM1 and FM2 for the lenses 31 and 33.
It is arranged at a position conjugate with. This light passes through an opening formed in the field stop 34, reaches the photoelectric conversion element 36 via the lens 35, and is photoelectrically converted. Since the photoelectric conversion element 36 is disposed at the position of the pupil with respect to the reference marks FM1 and FM2, it outputs a signal indicating the intensity of incident light.

On the other hand, the reference position mark 30b is used when measuring the measurement center of the plate alignment sensors 20a to 20d described later. Therefore, the reference position mark 3
Ob is illuminated with detection light emitted from the plate alignment sensors 20a to 20d. Reference position mark 30
The detection light that has passed through the periphery of b is a lens 31, an aperture 32,
Then, the light enters the field stop 34 via the lens 33 in order, but is blocked by the field stop 34. The plate alignment sensors 20a to 20d transmit the detection light to the reference position mark 30.
Reference position mark 3 using reflected light obtained by irradiating b
0b, the reference position mark 30b
It is not necessary to photoelectrically convert the detection light transmitted through the periphery of the photodetector with the photoelectric conversion element 36 to obtain a signal indicating the light intensity. For this reason, the field stop 34 is used to measure the center (exposure center) of the projected image of the pattern formed on the mask when the slit pattern 30a is used.
When the measurement center of the plate alignment sensors 20a to 20d is measured, the detection light transmitted around the reference position mark 30b is shielded. Incidentally, as shown in FIG. 2, the reference marks FM1 and FM2
The reason why two are formed on the stage PS is to reduce the amount of movement of the stage PS.

Returning to FIG. 1, beside the projection optical system PL,
Further, four off-axis type plate alignment sensors 20a to 20d are arranged. The four plate alignment sensors 20a to 20d form a sensor section according to the present invention. The plate alignment sensors 20a to 20d correspond to the reference marks FM shown in FIG.
1, the position information of the reference position mark 30b formed on the FM2 and the position information of the mark formed on the plate P are measured. As shown in FIG. 1, a plurality of plate alignment sensors 20a
20d is provided in order to reduce the amount of movement of the stage PS and to improve the throughput. In the example shown in FIG. 1, four plate alignment sensors 20a to 20d are provided.

Here, the plate alignment sensor 20
The arrangement of a to 20d will be described. FIG. 6 is a schematic diagram showing the relationship between the marks formed on the plate P and the arrangement of the plate alignment sensors 20a to 20d. The position measuring device measures the position information of the mark formed on the plate P on the stage PS, and calculates the X
A linear displacement of the plate P is obtained by obtaining five components of a displacement amount in the axial direction (shift), a displacement amount in the Y-axis direction, a rotation amount (rotation) of the plate P, a magnification (scaling), and an orthogonality. Calculate the amount. Here, in order to obtain these five components, at least five measurement results are required. Therefore, when position information in the X-axis direction and position information in the Y-axis direction can be obtained from one mark formed on the plate P, it is sufficient to measure at least three marks. However, since the plate P is subjected to a heat treatment such as an annealing process, the plate P may be nonlinearly distorted by the influence of heat. Therefore, considering the shape and measurement accuracy of the plate P, as shown in FIG. 6, a straight line L1 and a second line L1 extending in the X-axis direction as the first direction passing through the center of the plate P as the position detection target. First quadrant R divided by a straight line L2 extending in the Y-axis direction as the direction
A first, a second quadrant R2, a third quadrant R3, and a fourth quadrant R4 are set, a mark is formed in each of the first quadrant R1 to the fourth quadrant, and a plate alignment sensor is arranged for each mark. Is preferred.

In the example shown in FIG. 6, a mark AM3 is formed in the first quadrant R1, a plate alignment sensor 20c is arranged corresponding to the mark AM3, and a mark AM4 is formed in the second quadrant R2. A plate alignment sensor 20d is arranged corresponding to the mark AM4, and a mark AM1 is formed in the third quadrant R3.
a, a mark AM2 is formed in the fourth quadrant R4, and a plate alignment sensor 20b is arranged corresponding to the mark AM2. Mark AM1 to AM4
Is preferably formed at a position close to the four corners of the plate P from the viewpoint of improving the measurement accuracy such as the rotation amount and the magnification of the plate P. Further, in the example shown in FIG. 6, the marks AM1 to AM4 have the same shape as the reference position mark 30b (see FIG. 5) formed on the reference marks FM1 and FM2. Further, areas SA1 to SA4 shown in FIG. 6 indicate areas where the images of the patterns formed on the masks M1 to M4 are respectively transferred. In FIG. 6, the sizes of the marks AM1 to AM4 are exaggerated.

Next, the plate alignment sensors 20a to 20d as a sensor part forming a part of the position measuring device according to one embodiment of the present invention will be described in detail. FIG.
FIG. 2 is a diagram showing a configuration example of an optical system of plate alignment sensors 20a to 20d forming a part of a position measuring device according to an embodiment of the present invention. Incidentally, since the configuration of each of the plate alignment sensors 20a to 20d is the same, FIG.
2 shows only the configuration of the plate alignment sensor 20a as a representative. In FIG. 7, 40 is 4
This is a halogen lamp that emits light having a wavelength bandwidth of about 00 to 800 nm. Here, the reason for using the halogen lamp 40 as a light source is that when a single-wavelength light is irradiated on a photosensitive agent such as a photoresist applied on the plate P, multiple interference occurs, resulting in a measurement error. This is to prevent as much as possible.

The light emitted from the halogen lamp 40 is
After being converted into parallel light by the condenser lens 41,
The light enters the dichroic filter 42. The dichroic filter 42 is composed of a plurality of filters configured to freely enter and exit the optical path of the light emitted from the halogen lamp 40. By changing the combination of filters inserted into the optical path, a predetermined Only the light in the wavelength band is selected and transmitted. For example, of the light emitted from the halogen lamp 40, light in a blue region (wavelength region:
About 420-530 nm), light in the red region (wavelength region: about 580-730 nm), only light in the yellow region,
Alternatively, white light (almost all of the wavelength band of light emitted from the halogen lamp 40) can be transmitted.

The light transmitted through the dichroic filter 42 is incident on a condenser lens 43 set so that one of the focal points is located substantially at the position of the incident end 44a of the optical fiber 44. The optical fiber 44 has one entrance end and four exit ends, and each exit end is a plate alignment sensor 2
0a to 20d are respectively guided inside. The halogen lamp 40, the condenser lens 41, the dichroic filter 42, and the condenser lens 43 are provided outside the chamber of the exposure apparatus in order to avoid thermal effects, and light transmitted through the dichroic filter 42 is It is configured to guide each of the alignment sensors 20a to 20d.

The light emitted from one emission end 44b of the optical fiber 44 is used as the detection light IL1. The detection light IL1 illuminates the condenser lens 45 and the field stop 46. The field stop 46 detects the detection light IL on the image formation plane FC.
It is provided to define one irradiation area. Field stop 4
The detection light IL1 that has passed through 6 enters a half mirror 49 via a relay lens 48, which branches light transmission and light reception. The detection light IL1 reflected by the half mirror 49 is imaged on the image plane FC via the objective lens 50. Optical fiber 44, condenser lens 45, field stop 4 described above
6. The relay lens 48, the half mirror 49, and the objective lens 50 form an irradiation optical system. When the mark AM1 or the reference mark FM1 formed on the plate P is arranged on the image plane FC, the reflected light is transmitted through the objective lens 50, the half mirror 49, and the second objective lens 51 in this order to the image sensor 52. Is formed on the imaging surface of. In addition, the above objective lens 5
0, the half mirror 49, the second objective lens 51, and the imaging device 52 form a light receiving optical system.

The imaging device 52 sequentially converts the optical image formed on the imaging surface into an image signal while scanning the optical image in a predetermined scanning direction.
An image signal is output to the main control system 15. The main control system 15
Image processing is performed on the image signal output from the image sensor 52 to determine, for example, a shift amount of the center position of the mark from the center position of the imaging surface of the image sensor 52. Laser interferometer 14X,
Since the position of the stage PS in the X-axis direction and the Y-axis direction and the stage position information indicating the amount of rotation of the stage PS are always input to the main control system 15 from the main control system 15, the main control system 1
5 obtains the position information of the mark being measured based on the stage position information and the shift amount of the center position of the center position mark on the imaging surface of the imaging element 52.

Here, the plate alignment sensor 20
Since the size of the measurement field of view a to 20d is limited to some extent, the plate AM1 and the reference mark FM
It is often difficult to accurately arrange the reference position mark 30b formed on the center of the plate alignment sensors 20a to 20d. Therefore, in this embodiment,
First, rough position information of the mark is obtained, and based on the position information, the plate P is moved to dispose the mark at the measurement center of the plate alignment sensors 20a to 20d, and then the position information is obtained with high accuracy. Conventionally, plate alignment sensors equipped with an image sensor measure the approximate position information of the mark by setting the optical magnification of the light-receiving optical system low, and then set the optical magnification to a high value to achieve high-precision position information. However, there is a problem in that it takes time to switch the magnification and the throughput is reduced. In the present embodiment, the imaging surface of the imaging element 52 is different depending on whether rough position information is measured (hereinafter, referred to as search measurement) or when position information is measured with high accuracy (hereinafter, referred to as fine measurement). By devising the measurement processing by providing a measurement area, a decrease in throughput is prevented.

FIG. 8 is a diagram showing a measurement area for search measurement and a measurement area for fine measurement. In FIG. 8, F
P indicates an imaging surface of the imaging device 54, and the imaging device 54
Is set, for example, in the X-axis direction. As shown, a measurement area SC1 for fine measurement in which the longitudinal direction is set in the X-axis direction including the center of the imaging plane FP, and the longitudinal direction is set in the Y-axis direction including the center of the imaging plane FP. The measurement area SC2 for the fine measurement is set. These measurement areas SC1 and SC2 form a central measurement area. Further, around the imaging plane FP, the measurement areas W11 and W12 and the measurement area W2 forming a peripheral measurement area are provided.
1, W22 is set. The measurement areas W11 and W12 as the first measurement units have their longitudinal directions set in the X-axis direction,
The measurement regions W2 and W22 as the measurement units have their longitudinal directions set in the Y-axis direction. In the case of search measurement, the main control system 15 performs image processing of an image signal output from the image sensor 52, and performs measurement processing on the measurement areas W11, W12, W21, and W22.
The center position of the mark is calculated by detecting the end portion (edge position) of the image of the mark formed on the image plane, and the shift amount from the center position of the imaging plane FP is obtained. In the case of fine measurement, the center position of the mark is calculated by detecting the end (edge position) of the image of the mark formed in the measurement areas SC1 and SC2, and the amount of deviation from the center position of the imaging plane FP is calculated. Ask for. The details of this measurement operation will be described later.

As described above, the plate alignment sensor 20a as a sensor unit forming a part of the exposure apparatus according to the embodiment of the present invention and the position measuring apparatus according to the embodiment of the present invention.
The configuration examples of the position measurement device and the exposure device according to the embodiment of the present invention will be described next. FIG. 9 is a flowchart showing a schematic operation of the exposure apparatus according to the embodiment of the present invention when measuring the baseline amount. In the exposure apparatus of this embodiment, first, the mask M1 is placed on the mask holder MS, and the mask observation systems 18a and 18b shown in FIG. 1 apply the position measurement marks drawn outside the pattern area on the mask M1. By irradiating the detection light and receiving the reflected light, the position information of the position measurement mark is measured. The measured position information is the main control system 1
5, the main control system 15 performs fine movement of the mask stage MS based on the position information to adjust the position of the mask M1, arranges the mask M1 at a predetermined position, and obtains the position information at that time (for example, The position information indicating the center position of the mask M1) is stored (step S10). Further, the reflection plate RF0 and the reference mark FM provided on the stage PS are provided.
1, FM2 is projected from the stage PS, and the upper surfaces of these members are set to be substantially flush with the upper surface of the plate P when the plate P is placed on the stage PS.

Next, the main control system 15 moves the stage PS to position the reflector RF0 (see FIG. 2) at the projection center of the projection optical system PL, and the autofocus mechanism 17 moves the stage PS in the Z-axis direction. The position information is measured (step S12). When detecting the position information of the stage PS in the Z-axis direction, the light projecting system 17a irradiates detection light onto the reflector RF0 from an oblique direction of the reflector RF0, and the reflected light is received by the light receiving system 17b. The main control system 15 adjusts the position of the stage PS in the Z-axis direction based on the light reception result output from the light receiving system 17b, thereby mounting the reflection surface RF0 (corresponding to the upper surface of the plate P) on the mask stage MS. It is positioned at a position conjugate with the placed mask M1.

When the above processing is completed, a portion of the mask M1 mounted on the mask stage MS where the mark for position measurement is formed is irradiated with exposure light, and a photoelectric measurement device provided on the stage PS (FIG. 3) is performed to measure the center (exposure center) of the projected image of the pattern formed on the mask mounted on the mask stage MS (step S14). In measuring the exposure center, the main control system 15 moves the stage PS to dispose the reference mark FM1 near the exposure center, and then irradiates the exposure light to the position measurement mark formed on the mask M1 with the exposure light. The image of the mark for position measurement is transferred to the reference mark F via the projection optical system PL.
Irradiated on M1. The light that has passed through the slit pattern 30a (see FIG. 4) formed in the reference mark FM1 enters the field stop 34 through the lens 31, the stop 32, and the lens 33 in order, passes through the field stop 34, and further passes through the lens. The light reaches the photoelectric conversion element 36 via 35 and is subjected to photoelectric conversion.

The signal output from the photoelectric conversion element 36 is
This is a signal indicating the intensity of light incident on the photoelectric conversion element 36, and this signal is output to the main control system 15. Main control system 1
Reference numeral 5 denotes a state in which a signal is output from the photoelectric conversion element 36, the stage is moved via the stage drive systems 16X and 16Y, and the stage position information output from the laser interferometers 14X and 14Y and the stage position information are output from the photoelectric conversion element 36. Obtain the relationship with the output signal. Since the position measurement mark formed on the mask M1 has a substantially cross shape, the mark is output from the photoelectric conversion element 36 when the position where the image of the mark is irradiated coincides with the position of the slit pattern 30a. Signal is maximum. Therefore, when the signal output from the photoelectric conversion element 36 is maximized, the laser interferometer 14X, 1
The exposure center is measured by obtaining the stage position information output from 4Y. The measurement of the exposure center may be performed using either the reference mark FM1 or the reference mark FM2.

Next, each plate alignment sensor 20
Measurement of the measurement center of a to 20d is performed (Step S1)
6). In this measurement, the main control system 15 performs control to sequentially measure the position information of the reference mark FM1 shown in FIG. 2 by the plate alignment sensors 20a and 20d.
Control for sequentially measuring the position information of the reference mark FM2 by the plate alignment sensors 20b and 20c is performed. Thus, the reference mark FM is placed at a different position on the stage PS.
By arranging 1 and FM2, the amount of movement of the stage PS can be reduced. As a result, the size of the stage PS can be reduced.

Now, the plate alignment sensor 20a
The method of measuring the measurement center will be described by taking as an example the case where the measurement center is measured. First, the main control system 15 moves the stage via the stage drive systems 16X and 16Y, and arranges the reference mark 20a immediately below the plate alignment sensor 20a. Next, light having a wavelength bandwidth of about 400 to 800 nm is emitted from the halogen lamp 40 shown in FIG. This light passes through a lens 41, a dichroic filter 42, and a condenser lens 43 in this order and enters an incident end 44.
The light enters the optical fiber 44 from a. The light incident from the incident end 44a is guided into the plate alignment sensor 20a by the optical fiber 44. 1 of optical fiber 44
Light emitted from the two emission ends 44b is used as detection light IL1. The detection light IL1 illuminates a field stop 46 via a condenser lens 45.

The detection light IL1 transmitted through the field stop 46 passes through the relay lens 48, is reflected by the half mirror 49, and is focused by the objective lens 50. Here, FIG.
Referring to FIG. 7, even if the detection light IL1 illuminates the reference position mark 30b, the detection light IL1 is not received by the photoelectric conversion element 36 because it is shielded by the field stop 34.
Light (reflected light or diffracted light) obtained by irradiating the detection light IL1 onto the reference position mark 30b is transmitted through the objective lens 50, the half mirror 49, and the second objective lens 51 to the image sensor 52.
And is converted into an image signal.

FIG. 10 is a diagram showing an example of an image of the reference position mark 30b formed on the image pickup surface of the image pickup device 52.
In FIG. 10, for simplicity of description, the imaging surface F
It shows a state where the image is formed in a state where the center position of the image Im1 of the reference position mark 30b is arranged at the center of P. When the image Im1 of the reference position mark 30b is displaced from the imaging plane FP, the search measurement and the fine measurement are sequentially performed. Image Im1 of reference position mark 30b
Is disposed substantially at the center of the imaging plane FP as shown in FIG. 10, the main control system 15 performs fine measurement. In the fine measurement, the main control system 15
The edge position of the image formed on the imaging plane FP based on the change in the signal intensity in the X-axis direction in the measurement area SC1 set in the imaging area FP and the change in the signal intensity in the Y-axis direction in the measurement area SC2 Is detected, and the image Im1 of the reference position mark 30b with respect to the imaging plane FP is determined from the interval between the edge positions.
Of the center position in the X-axis direction and the Y-axis direction are obtained.

Each plate alignment sensor 20a-2
When the measurement of the measurement center of 0d is completed, the main control system 15
From the exposure center obtained in step S14 and the measurement centers of the plate alignment sensors 20a to 20d obtained in step S16, each plate alignment sensor 20a
The base line amount for 〜20d is calculated (step S18). After the baseline amount is calculated, the main control system 15 determines whether there is another mask (step S20). The determination result in this step is “NO” when the exposure processing is performed using a single mask,
When performing exposure processing using a plurality of masks, “YE
S ". If the determination result in step S20 is “N
In the case of "O", the process ends, and in the case of "YES",
The mask mounted on the mask stage MS is exchanged (Step S22). For example, the mask stage M
When the mask M1 is placed on S, the mask M2
Will be replaced.

When the replacement of the mask is completed, the detection light is applied to the mark for position measurement drawn outside the pattern area on the mask M2 mounted on the mask stage MS by the mask observation systems 18a and 18b shown in FIG. By irradiating and receiving the reflected light, the position information of the position measurement mark is measured (step S24). The measured position information is output to the main control system 15. The main control system 15 calculates and stores the difference between the position information and the position information stored in step S10 (step S26). Next, the main control system 15 determines whether or not there is another mask (step S2).
8). If the result of this determination is “NO”, the measurement processing of the baseline amount ends. On the other hand, if the result of the determination in step S28 is "YES", the process proceeds to step S28.
Returning to step 22, the mask is replaced and the positional information of the mask placed on the mask stage MS is measured, and step S1 is performed.
Processing for obtaining a difference from the position information stored as 0 is performed.

As described above, in the present embodiment, when the exposure processing is performed using a plurality of masks, the baseline amount is obtained only for the mask initially placed on the mask stage MS. is there. The measurement of the baseline amount was not performed for the second and subsequent masks, but the difference with respect to the positional information of the mask placed first on the mask stage MS was obtained, and the measured baseline amount was corrected with this difference. Use the baseline amount.

The method of measuring the baseline amount has been described above. Next, the operation of mounting the plate P on the stage PS and measuring the position information of the plate P will be described. FIG. 11 shows the plate alignment sensor 20.
mark AM formed on the plate P by using a to 20d
It is a flowchart which shows the operation | movement at the time of measuring the positional information of 1-AM4. When the plate P is conveyed onto the stage PS, the position of the reference side of the plate P is measured by a potentiometer (not shown), and pre-alignment is performed by rotating the stage PS to mechanically adjust the position of the plate P in advance. (Step S30). The reflection plate RF0 and the reference marks FM1 and FM2 are immersed in the stage PS before the plate P is placed on the plate stage PS.

Next, the main control system 15 moves the stage PS to move the marks AM1 to AM4 formed on the plate P.
Are arranged near the measurement field of view of the plate alignment sensors 20a to 20d. At this time, the marks AM1 to AM4 are arranged at positions shifted by a predetermined amount (for example, several tens of μm) with respect to the plate alignment sensors 20a to 20d (step S32). This is to reduce the time required for image processing performed by the main control system 15 on image signals output from each of the plate alignment sensors 20a to 20d. That is, in the search measurement, the position information of the mark is obtained based on the image signal of the image of the mark formed in the measurement areas W11, W12, W21, and W22 shown in FIG. W21, W
Performing image processing on all 22 takes time. Therefore, in the X-axis direction, the measurement region W11 or the measurement region W
12. In the Y-axis direction, the time required for search measurement is reduced by processing only image signals obtained from the measurement region W21 or the measurement region W22. in this way,
When the number of the measurement areas is reduced, the marks are changed to the plate sensors 20a to 20d due to the influence of the magnification (scaling) of the plate P.
Since the position to be placed with respect to 20d is different for each plate P (for each mark to be measured), a process of setting a measurement area for each mark is required, and the time required for the process is lengthened accordingly. For this reason, the marks AM1 to AM4 are displaced by a predetermined amount with respect to the plate alignment sensors 20a to 20d in advance, so that the marks AM1 to AM4 for the alignment sensors 20a to 20d.
Since the arrangement direction and distance of 4 are constant, processing for setting a measurement area for each mark is required, and as a result, the time required for the measurement processing can be reduced.

When the arrangement of the marks AM1 to AM4 is completed, search measurement is performed using the plate alignment sensors 20a and 20b (step S). FIG. 12 is a diagram illustrating a state where search measurement is performed using the plate alignment sensors 20a and 20b. In FIG. 12, F
P1 indicates an imaging surface of the imaging element 52 provided in the plate alignment sensor 20a, and Im11 indicates an image of the mark AM1 formed on the imaging surface FP1. FP2 is an image pickup device 5 provided in the plate alignment sensor 20b.
2 shows an imaging surface, and Im12 shows an image of the mark AM2 formed on the imaging surface FP2.

In the example shown in FIG. 12, the marks AM1 and AM2 are displaced in the + X direction and the + Y direction with respect to the plate alignment sensors 20a and 20b, respectively, in step S32 shown in FIG.
In this case, the plate alignment sensors AM1, AM2
The measurement region W11 and the measurement region W21 are set in the imaging element 52 provided in. In the example shown in FIG.
The position of the image Im12 in the Y-axis direction with respect to the imaging surface FP2 is arranged in the −Y direction with respect to the position of the image Im11 in the Y-axis direction with respect to the imaging surface FP1. This is obtained when the plate P is arranged in a state of being rotated with respect to the alignment sensors 20a to 20d. Strictly speaking, when the plate P is rotated, the images Im11 and Im12 are also formed on the imaging surface F.
An image is formed while rotating each of P1 and FP2. However, since the marks AM1 and AM2 are formed at the corners of the plate P, the distance between them is about several hundred millimeters.
Since it is about several tens to several hundreds of microns, even if the plate P is slightly rotated, the images I of the marks AM1 and AM2
m1 and Im2 are hardly rotated and the imaging planes FP1 and FP1 are not rotated.
An image is formed on FP2.

The image formed on the image pickup surface FP1 of the image pickup device 52 provided in the plate alignment sensor 20a is converted into an image signal by the image pickup device 52 and output to the main control system 15. Similarly, the image formed on the imaging surface FP2 of the imaging device 52 provided in the plate alignment sensor 20b is the imaging device 5
The signal is converted into an image signal at 2 and output to the main control system 15. The main control system 15 includes a plate alignment sensor 20
Image processing is performed on the image signals output from a and 20b to determine the edge positions of the images Im11 and Im12 formed on the measurement areas W11 and W12, respectively. Imaging surface FP
The signal SX1 is obtained from the measurement area W11 set to 1, and the signal SY1 is obtained from the measurement area W21. Further, a signal SX2 is obtained from the measurement area W12 set on the imaging surface FP2, and a signal SY2 is obtained from the measurement area W21.

Referring to FIG. 12, the image forming position of image Im11 with respect to image pickup plane FP1 and image I with respect to image pickup plane FP2.
It can be seen that the edge positions (positions where the signal intensity changes) and the number of edges measured in the measurement areas W11 and W21 differ depending on the image formation position of m12. The main control system 15 includes an image sensor 52 provided in the plate alignment sensor 20a.
Measurement areas W11 and W21 set on the imaging plane FP1 of the image sensor 5 and the imaging element 5 provided in the plate alignment sensor 20b.
The measurement areas W11 and W21 set on the second imaging plane FP2 are known, and information on the shapes of the marks AM1 and AM2 is also stored in advance. Therefore, the center CP1 of the mark AM1 is calculated from the measured edge position, and the mark A
The center position CP2 of M2 is calculated. In the search measurement, the rotation amount and the shift amount of the plate P may be obtained, and in order to further reduce the time required for the search measurement, the position information of the mark AM1 in the X-axis direction, the position information in the Y-axis direction, and Only three of the four pieces of the position information of the mark AM2 in the X-axis direction and the position information in the Y-axis direction may be measured.

The case where the measurement areas W11 and W21 are set for the imaging planes FP1 and FP2 to obtain the position information of the marks AM1 and AM2 has been described above.
When 11, W21 is set, the edge position may not be obtained in some cases. For example, marks AM1, AM2
Are arranged so as to be largely displaced from the plate alignment sensors 20a and 20b. In such cases,
A process for obtaining the edge position by switching the measurement area is performed. FIG. 13 is a flowchart illustrating an example of a process of obtaining an edge position by switching a measurement area. Note that FIG.
Are performed individually by the individual plate alignment sensors 20a to 20d.

When the processing is started, first, the main control system 15 sets the measurement areas W11 and W12 (step S50), and performs processing for obtaining an edge in the measurement areas W11 and W21 (step S52). Next, it is determined whether or not an edge position has been obtained in the measurement area W11. If the edge position has been obtained (the determination result is “YES”), the process proceeds to step S62. On the other hand, when it is not obtained (when the determination result of step S54 is “NO”), the measurement area is changed to the measurement area W11.
Is set to switch to the measurement area W12, and the edge position is obtained within the measurement area W12 (step S56). Next, it is determined whether or not an edge position has been obtained in the newly set measurement area W12 (step S58). When the edge position is obtained (when the determination result is “YES”), the process proceeds to step S62. When the edge position is not obtained (when the determination result is “NO”), for example, an error display or a warning sound is issued. (Step S6)
0).

In step S62, it is determined whether or not an edge position has been obtained in the measurement area W21 in the processing in step S52. If this determination is "YES", the flow proceeds to step S68. On the other hand, when the determination result of step S62 is “NO”, the measurement area is set to the measurement area W2.
The setting for switching from 1 to the measurement area W22 is made, and the edge position is obtained in the measurement area W22 (step S42).
Next, it is determined whether or not an edge position has been obtained in the newly set measurement area W22 (step S66). When the edge position is obtained (when the determination result is “YES”), the process proceeds to step S68. When the edge position is not obtained (when the determination result is “NO”), the process proceeds to step S60 to perform error processing. . In step S68, a process of calculating the center position of the mark from the obtained X-axis direction edge position and Y-axis direction edge position is performed. As described above, in the present embodiment, when the edge position is not obtained, the processing of switching between the measurement area W11 and the measurement area W12 or the processing of switching between the measurement area W21 and the measurement area W22 is performed.

In the flow chart shown in FIG. 13, when the edge position is not obtained, the processing for obtaining the edge position is performed by switching the measurement area for which the edge position has not been obtained. In this processing, the measurement area W
If the edge position cannot be obtained in both steps 11 and W21, a new measurement area W12 is determined in step S56.
Is set and the edge position is obtained in the measurement area W12, then, in step S64, a process of setting a new measurement area W22 and obtaining the edge position in the measurement area W22 is performed. However, considering the time required for the processing, if the edge position cannot be obtained in both the measurement areas W11 and W21, the measurement area W11 and the measurement area W
It is preferable to switch 21 to the measurement area W12 and the measurement area W22 at the same time, and to obtain the edge position in parallel in the measurement areas W12 and W22.

Returning to FIG. 11, when the processing described above is performed and the search measurement of the marks AM1 and AM2 is completed by the plate alignment sensors 20a and 20b, the shift amount and the rotation amount of the plate P are determined based on the search measurement result. A calculation process is performed (step S36). Next, in order to prevent the rotation amount of the plate P from affecting the next measurement process (fine measurement), it is determined whether the rotation amount of the plate P is within a predetermined allowable range. (Step S38).

When the result of the determination in step S38 is "N
In the case of "O", the stage PS is rotated so that the rotation amount of the plate P falls within the allowable value in step S40, and the process proceeds to step S42. Further, if the plate P is in the X axis direction or Y
When the stage PS is shifted in the axial direction, the stage PS is moved in the X-axis direction or the Y-axis direction to perform positioning. On the other hand, if the result of the determination in step S38 is "YES", the flow proceeds directly to step S42. By performing the above processing, the plate alignment sensors 20a to 20a
Mark A on the imaging surface of the imaging device provided for each
The images of M1 to AM4 are respectively arranged as shown in FIG. FIG. 14 shows a plate alignment sensor 20a.
After adjusting the position of the plate P with respect to 20d,
FIG. 3 is a diagram illustrating an example of images of marks AM1 to AM4 formed on an imaging surface of an imaging element.

In FIG. 14, FP1 to FP4 indicate the imaging planes of the imaging elements provided in the plate alignment sensors 20a to 20d, and Im1 to Im4 indicate the images of the marks AM1 to AM4 formed on the plate P, respectively. As shown in FIG. 14, before the fine measurement, the measurement areas SC1 and SC set on each of the imaging surfaces FP1 to FP4 are set.
The plate P is adjusted so that 1 includes only the images of the four sides facing the mark elements on the U-shape that form the alignment marks AM1 to AM4.

Imaging planes FP1 to FP4 and marks AM to AM
After the images Im11 to Im14 of FIG. 4 are arranged in the relation shown in FIG.
Fine measurement is performed using d (step S4).
2). At this time, the plate alignment sensors 20a-
20d is an imaging plane F without moving the stage PS.
By measuring the center positions of the images Im1 to Im4 formed on P1 to FP4 almost simultaneously, the position information of the marks AM1 to AM4 is measured almost simultaneously. By this processing, the position information in the X-axis direction and the position information in the Y-axis direction of the marks AM1 to AM4 are obtained, respectively, and a total of eight position information can be obtained almost simultaneously, so that the time required for the measurement time is reduced. be able to. In step S42, the position information of the marks AM1 to AM4 is measured without moving the stage PS.
The time required for measurement can be drastically reduced as compared with the case where position information is measured using an alignment sensor of a system.

Next, the 8 obtained in the processing of step S42
So-called enhanced global
By performing a statistical calculation process called alignment (EGA) measurement, an error component such as linear distortion of the plate (plate P
(Shift, shift in the X-axis direction, shift in the Y-axis direction, rotation amount (rotation) of plate P, magnification (scaling), five components of orthogonality, etc.) are obtained. A process of calculating the array coordinates of SA4 is performed (step S44). The process of measuring the position information of the mark formed on the plate P by the above process ends.
Next, the main control system 15 aligns the exposure area SA1 of the plate P with the exposure center based on the array coordinates of the exposure areas SA1 to SA4 obtained by the EGA measurement and the base line amount obtained in advance. Then, exposure light from the illumination optical system is irradiated onto the mask M1, and an image of a pattern formed on the mask M1 is transferred to the exposure area SA1 of the plate P via the projection optical system PL.

Next, the main control system 15 controls the mask stage M
The mask M1 mounted on S is replaced with a mask M2, and the stage PS is driven by stepping to align the plate P exposure area SA2 with the exposure center, thereby projecting the image of the pattern formed on the mask M2. Optical system PL
Is transferred to the exposure area SA2 via the. Hereinafter, similarly, the same processing is performed on the mask M3 and the mask M4, and all the exposure areas SA1 to SA4 set on the plate P are set.
Is exposed. Thus, a series of operations of the exposure processing ends.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be freely modified within the scope of the present invention. For example, in the above embodiment, the step-and-repeat type exposure apparatus has been described as an example, but the present invention is also applicable to a step-and-scan type exposure apparatus. In addition, the light source of the illumination optical system of the exposure apparatus of the present embodiment uses the g-line (436 nm) and the i-line (365 nm) emitted from the ultra-high pressure mercury lamp, but is not limited thereto, and the KrF excimer laser is used. (248 nm), ArF excimer laser (193n)
m), a laser beam emitted from an F ₂ laser (157 nm), or a charged particle beam such as an X-ray or an electron beam. For example, when an electron beam is used, a thermionic emission type lanthanum hexaborite (LaB ₆ ) or tantalum (Ta) can be used as an electron gun. Further, in the above-described embodiment, the case of manufacturing a liquid crystal display element has been described as an example. An exposure apparatus used to transfer a device pattern onto a semiconductor substrate, an exposure apparatus used to manufacture a thin-film magnetic head to transfer a device pattern onto a ceramic wafer, and an exposure apparatus used to manufacture an imaging device such as a CCD. The present invention can also be applied to

The reference position mark 30 formed on the reference marks FM1 and FM2 provided in the position measuring device of the present invention.
The marks AM1 to AM4 formed on the plate b and the plate P are not limited to the shapes shown in FIG. The reference position mark 30b and the marks AM1 formed on the plate P
The shape of AM4 can be appropriately designed according to processing such as image processing.

Next, an embodiment of a method of manufacturing a micro device using an exposure apparatus according to an embodiment of the present invention in a lithography process will be described. FIG. 15 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel,
FIG. 6 is a diagram showing a flowchart of a manufacturing example of a CCD, a thin-film magnetic head, a micromachine, and the like). As shown in FIG. 15, first, in step S70 (design step),
The function / performance design of the micro device (for example, the circuit design of a semiconductor device) is performed, and the pattern design for realizing the function is performed. Subsequently, in step S71 (mask manufacturing step), a mask (reticle) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S72 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

Next, in step S73 (wafer processing step), an actual circuit or the like is formed on the wafer by lithography or the like using the mask and the wafer prepared in steps S70 to S72, as described later. . Next, in step S74 (device assembly step), device assembly is performed using the wafer processed in step S73. Step S74 includes, as necessary, processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation).
Finally, in step S75 (inspection step), inspections such as an operation confirmation test and a durability test of the micro device manufactured in step S74 are performed. After these steps, the microdevice is completed and shipped.

FIG. 16 is a diagram showing an example of a detailed flow of step S73 in FIG. 15 for a semiconductor device. In FIG. 18, in step S81 (oxidation step), the surface of the wafer is oxidized. In step S82 (CVD step), an insulating film is formed on the wafer surface. Step S83 (electrode forming step)
In, electrodes are formed on a wafer by vapor deposition. In step S84 (ion implantation step), ions are implanted into the wafer. Each of the above steps S81 to S84 constitutes a pre-processing step in each stage of wafer processing, and is selected and executed according to a necessary process in each stage.

At each stage of the wafer process, when the above-mentioned pre-processing step is completed, a post-processing step is executed as follows. In this post-processing step, first, step S
At 85 (resist forming step), a photosensitive agent is applied to the wafer. Subsequently, in step S86 (exposure step), the circuit pattern of the mask is transferred to the wafer by the lithography system (exposure apparatus) and the exposure method described above. Next, in Step S87 (developing step), the exposed wafer is developed, and Step S87 is performed.
In step 88 (etching step), the exposed member other than the portion where the resist remains is removed by etching. Then, in step S89 (resist removing step), unnecessary resist after etching is removed. By repeating these pre-processing and post-processing steps, multiple circuit patterns are formed on the wafer.

If the microdevice manufacturing method of the present embodiment described above is used, the above-described exposure apparatus and the above-described exposure method are used in the exposure step (step S86), and the resolution is improved by the illumination light in the vacuum ultraviolet region. In addition, since the exposure amount can be controlled with high precision, a highly integrated device having a minimum line width of about 0.1 μm can be produced with a high yield.

In addition to a micro device such as a semiconductor element, a reticle or a mask used for an optical exposure apparatus, an EUV exposure apparatus, an X-ray exposure apparatus, an electron beam exposure apparatus, etc. The present invention is also applicable to an exposure apparatus that transfers a circuit pattern to a glass substrate, a silicon wafer, or the like. Here, in an exposure apparatus using DUV (deep ultraviolet) or VUV (vacuum ultraviolet) light, a transmission type reticle is generally used, and as a reticle substrate, quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride, quartz, or the like is used. In a proximity type X-ray exposure apparatus, electron beam exposure apparatus, or the like, a transmission mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate. Such an exposure apparatus is described in WO99
No./34255, WO99 / 50712, WO99 /
66370, JP-A-11-194479, JP-A-2000-12453
And JP-A-2000-29202.

[0081]

As described above, according to the present invention, the marks formed in each of the first to fourth quadrants are irradiated with the detection light almost simultaneously, and the detection light is irradiated on each of the marks. The position information of each mark is obtained almost simultaneously based on the obtained light. Therefore, unlike the conventional measurement, the position information of the mark can be measured without lowering the throughput because the stage information is not moved when measuring the position information of the mark. Also, since the position information of each of the marks formed in the first to fourth quadrants is measured, the position information of the mark necessary to calculate the distortion of the position detection object is provided throughout the position detection object. This provides an effect that the position information of the position detection target can be obtained with high accuracy. Further, according to the present invention, the image of the mark included in the light obtained by irradiating the mark with the detection light is based on the image formed on the peripheral measurement area set in the peripheral portion of the imaging surface of the image sensor. The approximate position information of the mark is measured, and the position detection object is moved based on the measurement result, and each mark is determined based on the image formed on the central measurement area set including the central portion of the imaging surface. Location information is obtained almost simultaneously. Therefore, before the position information is measured based on the image formed in the central measurement area,
Since the position of the position detection object is adjusted based on the rough position information of the mark, the position information of each mark can be measured at high speed even if the position detection object is displaced from the sensor unit. There is an effect that can be. In addition, since the mark for measuring rough position information and the mark for measuring high-precision position information are the same mark, it is possible to reduce the number of marks formed on the position detection target. effective. Furthermore, there is no need to switch the optical system (for example, switching of the magnification) between the case where rough position information is measured and the case where high-precision position information is measured, so that high-speed measurement can be performed. There is.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an overall configuration of an exposure apparatus according to an embodiment of the present invention including a position measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of members provided on a stage PS used when measuring various types of position information.

FIG. 3 is a cross-sectional view illustrating a configuration of a photoelectric measurement device used when obtaining a baseline amount on a stage PS.

FIG. 4 is a diagram showing an example of a slit pattern 30a and a reference position mark 30b formed on reference marks FM1 and FM2.

FIG. 5 is an enlarged view of a reference position mark 30b.

FIG. 6 is a schematic diagram illustrating a relationship between marks formed on a plate P and arrangements of plate alignment sensors 20a to 20d.

FIG. 7 is a diagram showing a configuration example of an optical system of plate alignment sensors 20a to 20d forming a part of the position measuring device according to one embodiment of the present invention.

FIG. 8 is a diagram showing a measurement area for search measurement and a measurement area for fine measurement.

FIG. 9 is a flowchart illustrating a schematic operation of the exposure apparatus according to the embodiment of the present invention when measuring a baseline amount.

FIG. 10 is a diagram illustrating an example of an image of a reference position mark 30b formed on an imaging surface of an imaging element 52.

FIG. 11 shows plate alignment sensors 20a to 20
marks AM1 to AM formed on plate P using
4 is a flowchart showing an operation when measuring position information of No. 4;

FIG. 12 shows plate alignment sensors 20a, 20
It is a figure showing signs that search measurement is performed using b.

FIG. 13 is a flowchart illustrating an example of a process of switching a measurement area to obtain an edge position.

FIG. 14 shows plate alignment sensors 20a to 20
FIG. 10 is a diagram illustrating an example of images of marks AM1 to AM4 formed on an imaging surface of an imaging element after the position of a plate P is adjusted with respect to d.

FIG. 15 is a view showing a flowchart when manufacturing a micro device.

16 is a diagram showing an example of a detailed flow of step S73 in FIG. 15 in the case of a semiconductor device.

[Explanation of symbols]

Reference Signs List 2 light source (exposure light source) 15 main control system (control system, positioning means) 16X, 16Y stage drive system 20a to 20d plate alignment sensor (sensor unit) 52 imaging device AM1 to AM4 mark FP, FP1 to FP4 imaging surface IL1 detection Light Im1 to Im4 Image (image of mark) L1 Straight line (straight line extending in first direction) L2 Straight line (straight line extending in second direction) M1 to M4 Mask P plate (substrate, object to be detected) PS stage R1 First quadrant R2 Second quadrant R3 Third quadrant R4 Fourth quadrant SC1, SC2 Measurement area (central measurement area) W11, W12, W21, W22 Measurement area (peripheral measurement area)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Manabu Toguchi 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation (72) Inventor Yutaka Hobiki 3-2-2, Marunouchi, Chiyoda-ku, Tokyo F term in Nikon Corporation (reference) 2F065 AA03 BB02 BB29 CC20 DD03 FF42 FF55 GG02 JJ01 JJ03 JJ05 JJ26 LL02 LL22 LL30 MM02 PP12 QQ21 QQ32 5F046 BA04 DA14 EB01 EB03 ED01 ED02 ED03 FA03 FC10 FA10

Claims (10)

[Claims] 1. A first quadrant and a fourth quadrant, each of which is divided by a straight line extending in a first direction and a straight line extending in a second direction orthogonal to the first direction, passing through a central portion of the position detection object. At least four sensor units that are provided corresponding to each of the marked marks and measure position information of the corresponding mark based on light obtained by irradiating the corresponding mark with detection light; Position information of the mark formed in each quadrant in the first direction and the second direction,
A position measurement device comprising: a control system that simultaneously measures at least the four sensor units. 2. The control system according to claim 2, wherein the at least four sensor units include an image sensor that receives an image of the mark included in light obtained by irradiating the mark with the detection light on an image capturing surface and captures the image. 2. The position measurement according to claim 1, wherein the position of each of the marks is simultaneously measured based on an image of the mark formed in a center measurement area including a center of the imaging surface. 3. apparatus. 3. The apparatus according to claim 1, further comprising a stage movable with the position detection object mounted thereon, wherein the control system is configured to form an image of the mark formed on a peripheral measurement area set in a peripheral portion of the imaging surface. 3. The position measuring device according to claim 2, wherein the approximate position information of the mark is measured based on the measurement result, the stage is moved based on the measurement result, and the measurement is performed using the central measurement region. 4. An exposure apparatus comprising: an exposure light source for emitting exposure light; irradiating the exposure light onto a mask to transfer an image of a pattern formed on the mask onto the substrate; And a position measuring device according to claim 3 for measuring position information of a mark formed on the substrate, wherein the stage is moved based on a measurement result of the position measuring device, and An exposure apparatus further comprising a positioning unit for performing relative positioning. 5. Each of the first to fourth quadrants, which is divided by a straight line extending in a first direction and a straight line extending in a second direction orthogonal to the first direction, passing through a central portion of the position detection object. Irradiation step of irradiating each of the marks with detection light substantially simultaneously; and a measurement step of obtaining position information of each of the marks almost simultaneously based on light obtained by irradiating each of the marks with the detection light. Characteristic position measurement method. 6. The method according to claim 1, wherein the measuring step includes forming, in an image of the mark included in light obtained by irradiating the mark with the detection light, a peripheral measurement area set around an imaging surface of an image sensor. A first measurement step of measuring approximate position information of the mark based on an image to be imaged; a movement step of moving the position detection target based on a measurement result in the first measurement step; and a center of the imaging surface. 6. A position measurement method according to claim 5, further comprising: a second measurement step of obtaining position information of each of said marks substantially simultaneously based on an image formed on a central measurement region set including a portion. 7. The method according to claim 6, wherein the first measuring step measures position information of at least two of marks formed in each of the first to fourth quadrants.
The position measurement method described. 8. The peripheral measurement area includes two first measurement units along the first direction and two second measurement units along the second direction.
A measurement unit is set, and the first measurement step is performed in accordance with a measurement result obtained by using one first measurement unit and one second measurement unit. The position measurement method according to claim 6 or 7, further comprising a switching step of performing measurement by switching to two measurement units or another first measurement unit and another second measurement unit. 9. A step of arranging the position detection object such that each mark is arranged at a position shifted by a predetermined amount with respect to each of the sensor units before measuring position information of each of the marks. The position measurement method according to any one of claims 6 to 8, wherein: 10. A position measurement for measuring position information of a mark formed on a substrate using the substrate as the position detection target, using the position measurement method according to claim 5. A step of performing relative positioning between a mask and the substrate based on a measurement result in the position measurement step, irradiating the mask with exposure light, and forming an image of a pattern formed on the mask into the mask. A method for manufacturing a device, comprising: a transfer step of transferring onto a substrate; and a developing step of developing the transferred substrate.