JPH08181062A - Positioning device and positioning method - Google Patents

Abstract

PURPOSE: To quickly position a substrate and a mask in a highly precise manner by a method wherein, after the position of an alignment mark has been detected, the mark is relatively moved to the position in the vicinity of the optical axis of a detection optical system based on the result of detection, and the position of the mark is redetected. CONSTITUTION: The position of a positioning mark 4 is detected by processing the information obtained by image-pickup using an image treatment unit. Then, the deviation of the position of the positioning mark 4 against the optical axis 10 of a detection optical system 7 is computed based on the obtained result of detection and the correction value of the position of the positioning mark 4 is computed. The control signal corresponding to the above-mentioned correction value is inputted to a driving motors 6A and 6B. The positioning mark 4 is moved to the position in the vicinity of the optical axis 10 by the movement of a stage 3. Subsequently, the position of the positioning mark 4, which is image-formed on the position detecting sensor 8, is redetected when the positioning mark 4 is moved to the position in the vicinity of the optical axis 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning apparatus and a positioning method, and is suitable for use in, for example, a projection exposure apparatus when the position of a substrate is obtained and positioned by image processing.

[0002]

2. Description of the Related Art Conventionally, when an original pattern formed on a mask is exposed on a photosensitive substrate by a projection optical system, a positioning device detects a positioning mark for alignment provided on the photosensitive substrate. Then, the position of the photosensitive substrate is determined. This positioning device corresponds to a position detection sensor (for example, a television camera) that forms an image of an alignment positioning mark attached to a photosensitive substrate placed on a stage via a detection optical system, and a position detection sensor corresponding to the image. An image processing unit for image-processing the image signal to obtain the position of the positioning mark in the image.

In this positioning device, for example, an image taken by a television camera monitors a wide range with respect to the positioning mark. As a result, a wide field of view can be secured, and thus the positioning mark can be detected even if the positioning of the positioning mark is restricted or the photosensitive substrate on which the positioning mark is attached is not accurately conveyed or mounted.

FIG. 8 shows a procedure for detecting a positioning mark in a conventional positioning device. Starting from step SP1, in step SP2, a positioning mark is searched for by a position detection sensor via a detection optical system. That is, the positioning mark is moved relative to the detection optical system, and the positioning mark is placed within the image pickup range of the detection optical system for image pickup. Next, in step SP3, the position of the positioning mark is obtained by processing the image information obtained by the image pickup by the image processing unit, and the processing ends in step SP4.

[0005]

In the conventional positioning mark detection system as described above, since the detection optical system has a wide field of view, the optical characteristics of the detection optical system are good or bad.
Even if the optical characteristics are good in the vicinity of the optical axis, the optical characteristics may be poor in the peripheral area. For example, there is a problem that the position information of the mark obtained from the captured image information may differ from the actual position of the positioning mark due to the influence of the image distortion such as distortion and the light amount difference between the periphery and the center of the detection optical system. Atsuta

From the viewpoint of optical characteristics, it is difficult to process high-precision optical parts, and it is also difficult to process optical parts in a large size. As a result, the field of view of the detection optical system having good optical characteristics is narrowed, and there is a problem that the positioning mark must be detected by repeatedly detecting and processing a plurality of images in a narrow range.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a positioning device and a positioning method capable of positioning a substrate or a mask with higher accuracy and speed.

[0008]

In order to solve such problems, in the present invention, the mask (11) or the photosensitive substrate () is detected by detecting the alignment mark (4) on the mask (11) or the photosensitive substrate (2). Positioning device ((1), which positions 2) with respect to a preset reference,
(20)), the photosensitive substrate (2) or the mask (1
1) is provided with a mark (4) for alignment, the mark (4) is imaged through a detection optical system (7), and the mark (4) is processed by processing the information obtained by the imaging. Position detecting means ((8), which detects the position of 4),
(9)) and the detected mark (4) is moved into the imaging area by the detection optical system (7) to detect the position of the mark (4), and then the photosensitive substrate (4) is detected based on the detection result. Alternatively, the detected mark (4) is detected by moving the mask (2) and the optical axis (10) of the detection optical system (7) relative to each other in the direction orthogonal to the optical axis (10). The driving means ((5
A), (5B), (6A), (6B), (22A),
(22B)), and after the relative movement, mark (4) again.
Detect the position of.

Further, in the present invention, the driving means is made of parallel plate glass ((31), (32A), (32B)), and the optical axis (10) with respect to the position of the measured mark (4).
And a parallel plate glass ((31), (32A), (32B)) is driven based on the calculation result by the calculation means (9). After moving 10) to a position near the mark (4),
The position of the mark (4) is detected again.

Further, according to the present invention, the alignment mark (4) on the mask (11) or the photosensitive substrate (2) is detected to detect the mask (11) or the photosensitive substrate (2) with respect to a preset reference. In the positioning method for positioning, the alignment mark (4) provided on the photosensitive substrate (2) or the mask (11) is detected by an optical system (7).
The position of the mark (4) is detected by processing the information obtained by the image pickup through the image pickup device, and the detected mark (4) is placed in the image pickup area by the detection optical system (7). After moving to detect the position of the mark (4), the photosensitive substrate (2) or mask (11) and the optical axis (10) of the detection optical system (7) are moved to the optical axis (10) based on the detection result. ), The detected mark (4) is moved to a position in the vicinity of the optical axis (10) of the detection optical system (7), and after the relative movement, the mark (4) is moved again. Detect the position.

[0011]

After the position of the alignment mark (4) is detected, the mark (4) is relatively moved to a position near the optical axis (10) of the detection optical system (7) based on the detection result. After the relative movement, the position of the mark (4) is detected again. As a result, a highly accurate and quick positioning device ((1), which uses image information of an area where the influence of image distortion is small,
(20)) and the positioning method can be realized.

The position error of the optical axis (10) with respect to the measured position of the mark (4) is calculated by the calculating means (9),
The parallel plate glass (31) is driven based on the calculation result by the calculating means (9) to move the optical axis (10) to a position near the mark (4), and then the position of the mark (4) is detected again. By doing so, it is possible to realize a highly accurate positioning device (30) and a positioning method that are less affected by image distortion.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) First Embodiment In FIG. 1, reference numeral 1 generally shows a schematic structure of an exposure apparatus provided with a positioning device 12 according to a first embodiment of the present invention. The photosensitive substrate 2 is held on a stage 3, and the photosensitive substrate 2 is provided with a positioning mark 4 for recognizing the position of the photosensitive substrate 2. The position of the stage 3 is detected by a length measuring device such as the light wave interferometers 5A and 5B attached to the stage 3, the interferometer 5A is position information in the X-axis direction of the stage 3, and the interferometer 5B is the Y of the stage 3. Detects axial position information.

The stage drive motor 6A moves the stage 2 in the X-axis direction based on the position information of the stage 3 in the X-axis direction detected by the interferometer 5A, and the stage drive motor 6B moves in the interferometer 5B. Therefore, the stage 3 is moved in the Y-axis direction based on the position information of the stage 3 detected in the Y-axis direction, thereby controlling the position of the stage 3. In addition, the mask 11 is irradiated with the light flux of the illumination optical system (not shown).
And the image of the illuminated mask 11 is exposed on the photosensitive substrate 2 directly or via an imaging optical system (not shown).

The position of the photosensitive substrate 2 is determined by detecting the positioning mark 4 with respect to its predetermined reference. That is, using the mark detecting optical system 7, for example, C
An image of the positioning mark 4 is formed on the position detection sensor 8 which is a television camera including a CD, and an image signal corresponding to this image is image-processed by the image processing unit 9 in the image of the positioning mark 4. Find the position of.

The mark detecting optical system 7, the position detecting sensor 8 and the image processing unit 9 constitute a positioning device, and the positioning device 12 is provided at a predetermined position with respect to the exposure device 1 so that the position of the mark 4 can be adjusted. Detect the position. That is, the exposure apparatus 1 is used as the detection reference of the mark 4. Further, the positional relationship among the stage 3, the detection optical system 7, and the position detection sensor 8 is managed in advance by the coordinates of the interferometer at the time of initial setting.

FIG. 2 shows the procedure for detecting the positioning mark in the positioning device 12. As shown in FIG. 2, starting from step SP1, at step SP2,
The positioning mark 4 is moved within the imaging range of the detection optical system 7 to be imaged, and the information obtained by the imaging is processed by the image processing unit 9 to obtain the positioning mark 4
Position is detected (hereinafter referred to as rough detection).

Next, the process proceeds to step SP3, where step SP
The optical axis 1 of the detection optical system 7 based on the detection result obtained in 2.
The deviation of the position of the positioning mark 4 from 0 is calculated.
The positional relationship between the positioning mark 4 and the optical axis 10 at this time is shown in FIG. Then, in step SP4, a correction value for the position of the positioning mark 4 is obtained based on the position deviation obtained in step SP3, and a control signal corresponding to this correction value is input to the drive motors 6A and 6B. Then, the positioning mark 4 is moved to the optical axis 10 by moving the stage 3 in the X-axis and / or Y-axis directions based on the coordinates of the interferometer.
Move to a nearby position. The positional relationship between the positioning mark 4 and the optical axis 10 at this time is shown in FIG.

Next, in step SP5, when the positioning mark 4 is moved to a position near the optical axis 10, the position of the positioning mark 4 imaged on the position detection sensor 8 is detected again (hereinafter, referred to as high precision detection). Say) The detected position of the positioning mark 4 is calculated based on the interferometer coordinates, and the processing is ended in step SP6.

According to the above construction, after the positioning mark 4 is roughly detected, the positioning mark 4 is moved to a position near the optical axis 10 of the detection optical system 7 based on the correction value obtained by the rough detection. Since the position of No. 4 is detected with high accuracy, it is possible to detect the position of the mark with high accuracy while avoiding the influence of optical distortion in the peripheral portion of the position detection sensor 7. Thus, it is possible to position the photosensitive substrate 2 and the mask 11 with high precision with reference to the photosensitive substrate 2.

Further, according to the above configuration, the position of the positioning mark 4 is detected with high accuracy in the vicinity of the optical axis 10 of the detection optical system 7, so that the influence of the mounting of the position detecting sensor 8 or the like and the rotation error is avoided. be able to. Positioning mark 4
Since the detection of the positioning mark 4 when searching (positioning within the visual field (detection region) of the detection optical system) is roughly detected, the search time for the positioning mark 4 can be greatly shortened.

(2) Second Embodiment In FIG. 4, in which parts corresponding to those in FIG. 1 are designated by the same reference numerals, 20 is an outline of an exposure apparatus having a positioning device 13 according to a second embodiment of the present invention as a whole. Shows a typical configuration. The positioning device 13 roughly detects the positioning mark 4 and obtains a correction value similar to the above, and then moves the optical axis of the detection optical system 7 to a position near the positioning mark 4 based on the correction value. 4 and the optical axis 1 of the detection optical system 7
The position of 0 is almost aligned.

As shown in FIG. 4, the position detecting sensor unit 21 includes a detecting optical system 7, a position detecting sensor 8, and a position measuring unit such as an interferometer or an encoder for detecting the position information of the position detecting sensor unit 21 (see FIG. (Not shown). The position detection sensor unit 21 is driven by a drive motor 22A in the X-axis direction and by a drive motor 22B in the Y-axis direction.

That is, in the positioning device 13, the position detection sensor unit 21 is driven by the drive motors 22A and / or 22B based on the correction value obtained by roughly detecting the position of the positioning mark 4, and the light of the detection optical system 7 is detected. After moving the shaft 10 to a position near the positioning mark 4, the position of the positioning mark 4 is detected with high accuracy. In this case, the coordinate value of the positioning mark 4 is obtained by processing the coordinate value measured by the image processing unit 9 and the coordinate value of the interferometer together.

According to the above construction, the position detection sensor unit 21 is moved based on the correction value obtained by roughly detecting the positioning mark 4 to move the optical axis 10 of the detection optical system 7 to a position near the positioning mark 4. After the movement, the position of the positioning mark 4 is detected again as a highly accurate detection,
It is possible to obtain the same effect as that of the first embodiment described above.

(3) Third Embodiment In FIG. 5 in which parts corresponding to those in FIG. 1 are designated by the same reference numerals, reference numeral 30 generally indicates an exposure apparatus having a positioning device 14 according to a third embodiment of the present invention. Shows a typical configuration. In the positioning device 14, as shown in FIG. 5, the parallel plate glass 31 is provided in the optical path between the photosensitive substrate 2 and the detection optical system 7.
Is provided. The parallel plate glass 31 is rotated around the X axis by the drive motor 32A, and the drive motor 32A
It is rotated about the Y axis by B. Here, the parallel plate glass 31 may be divided into the whole parallel plate glass 31 and the glass portion 31A to be driven.

In the positioning device 14, as a rough detection, the position of the positioning mark 4 when the parallel flat plate glass 31 is in the initial state is detected by the image processing unit 9 and the deviation of the position of the optical axis 10 from the positioning mark 4 is detected. Is calculated,
The tilt direction and tilt angle of the parallel plate glass 31 from the initial state are obtained from the deviation of the position as the correction value. As shown in FIG. 6, the parallel flat plate glass 31 is tilted based on the obtained tilt direction and tilt angle to move the optical axis 10 in parallel to a position in the vicinity of the positioning mark 4, and then the positioning mark is detected again as a highly accurate detection. The position of 4 is detected.

According to the above construction, the parallel plate glass 31
The deviation of the position of the optical axis 10 with respect to the positioning mark 4 in the initial state is calculated, and the inclination direction and the inclination angle of the parallel flat plate glass 31 as the correction values are calculated from the calculation result, and based on this correction value The parallel plate glass 31 is driven to move the optical axis 10 in parallel to a position in the vicinity of the positioning mark 4 and then the position of the positioning mark 4 is detected again to obtain the same effect as that of each of the above-described embodiments. You can

The above-mentioned positioning devices 12, 13,
14 is also effective when confirming the relative position between the positioning marks 4 when another positioning mark 4 is present on the photosensitive substrate 2 when the stage 3 holding the photosensitive substrate 2 is moved by a certain amount. Is.

(4) Other Embodiments In each of the above embodiments, the photosensitive substrate 2 is held on the stage 3 and the photosensitive substrate 2 and the mask 11 are positioned with respect to the photosensitive substrate 2 as a reference. However, the present invention is not limited to this, and the mask 11 is held on the stage 3 as shown in FIG.
Even when the mask 11 and the photosensitive substrate 2 are positioned with reference to 1, the mask 11 can be positioned, and the same effect as that of the above-described embodiment can be obtained.

In the above embodiment, the stage 3
Position and the position of the position detection sensor unit 21
Although the case where measurement is performed using A and 5B or an encoder has been described, the present invention is not limited to this, and other position measuring means may be used as long as the coordinates are managed with sufficient resolution with respect to the required detection accuracy. You may use.

Further, in the above-mentioned embodiment, the fact that the optical axis 10 and the positioning mark 4 are at the same position when the position of the positioning mark 4 is detected by the highly accurate detection is utilized,
A low-resolution position detection sensor and a high-resolution position detection sensor are provided for each of the coarse detection and the high-precision detection, and the optical axis 10
May be divided into two and the low resolution position detection sensor and the high resolution position detection sensor may be selectively used.

Further, in the case of coarse detection, a method of taking in an image signal only in one field of 2: 1 interlace, a method of shortening a calculation algorithm different from high precision detection, and a method of high precision detection. In this case, considering that the mark position on the sensor is in a limited area by the rough detection, a method of improving the calculation speed in the image processing in the image processing by limiting the calculation area may be used.

Alternatively, the optical axis 10 may be divided into two parts, the low-magnification and high-magnification detection optical system 7 may be provided, and the low-resolution position detection sensor and the high-resolution position detection sensor may be arranged. In this case, coarse detection is performed through the low-magnification detection optical system 7, the positioning mark 4 is moved to the optical axis 10 based on the detection result, and then the positioning mark 4 is moved up through the high-magnification detection optical system 7. The accuracy is detected. Further, a variable magnification optical system may be provided between the detection optical system 7 and the position detection sensor 8 so that the magnification of the detection optical system 7 can be switched between low magnification and high magnification.

By combining these methods, the coordinates of the positioning mark 4 can be detected in a short time and with high accuracy.

In the above embodiment, after the rough detection,
I mentioned the case where high-precision detection was executed only once.
The present invention is not limited to this, and the position of the positioning mark 4 can be detected more accurately by repeating the processing procedure of FIG. 2 a plurality of times. For example, in the positioning device 1, a correction value is obtained again from the first high-precision detection, the stage 3 is moved based on this correction value, and the positioning mark 4 is further moved to a position in the vicinity of the optical axis 10. The position of 4 is detected with high accuracy.

[0038]

As described above, according to the present invention, after detecting the position of the alignment mark, the mark is relatively moved to a position near the optical axis of the detection optical system based on the detection result. By detecting the position of the mark again after the relative movement, it is possible to realize a highly accurate positioning device and positioning method in which the error in the detected position of the mark due to the influence of the image distortion is small.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a positioning device according to a first embodiment of the present invention.

FIG. 2 is a flow chart showing a procedure for detecting a positioning mark according to an embodiment.

FIG. 3 is a schematic diagram showing a positional relationship (A) between a positioning mark and an optical axis during rough detection and a positional relationship (B) between a positioning mark and an optical axis during high precision detection.

FIG. 4 is a perspective view showing a schematic configuration of a positioning device according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a schematic configuration of a positioning device according to a third embodiment of the present invention.

FIG. 6 is a side view for explaining parallel movement of an optical axis by a parallel plate glass.

FIG. 7 is a perspective view showing a schematic configuration of a positioning device when positioning a mask.

FIG. 8 is a flow chart showing a conventional procedure for detecting a positioning mark.

[Explanation of symbols]

1, 20, 30 ... Exposure device, 12, 13, 14 ... Positioning device, 2 ... Photosensitive substrate, 3 ... Stage, 4 ...
Positioning marks, 5A, 5B ... Interferometer, 6A, 6B ...
... Stage drive motor, 7 ... Detection optical system, 8 ... Position detection sensor, 9 ... Image processing unit, 10 ... Optical axis, 11 ... Mask, 21 ... Position detection sensor unit, 22A, 22B ... ... Position detection sensor unit drive motor, 31 ... parallel plate glass, 31A ... glass part, 32A, 32B ... parallel plate glass drive motor.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03F 9/02 H01L 21/30 525 X

Claims (3)

[Claims] 1. A positioning device for positioning the mask or the photosensitive substrate with respect to a preset reference by detecting an alignment mark on the mask or the photosensitive substrate, wherein the photosensitive substrate or the mask includes an alignment mark. Position detection means for detecting the position of the mark by imaging the mark via a detection optical system and processing the information obtained by the imaging, and the detected mark for detecting the position of the mark. After detecting the position of the mark by moving within the imaging area of the system, the photosensitive substrate or mask and the optical axis of the detection optical system are relatively moved in a direction orthogonal to the optical axis based on the detection result. Drive means for moving the detected mark to a position in the vicinity of the optical axis of the detection optical system by moving the detected mark, and after the relative movement, the mark is again moved. Positioning device and detecting the location. 2. The parallel plate glass, wherein the driving means is made of parallel plate glass, and has a calculating means for calculating a position error of the optical axis with respect to the detected position of the mark, based on the calculation result by the calculating means. The positioning device according to claim 1, further comprising: driving the optical axis to move the optical axis to a position near the mark, and then detecting the position of the mark again. 3. A positioning method for positioning the mask or the photosensitive substrate with respect to a preset reference by detecting an alignment mark on the mask or the photosensitive substrate, the alignment method being provided on the photosensitive substrate or the mask. The mark is imaged through the detection optical system, the position of the mark is detected by processing the information obtained by the image pickup, and the detected mark is moved into the image pickup area by the detection optical system. After detecting the position of the mark, the detection is performed by moving the photosensitive substrate or mask and the optical axis of the detection optical system relatively in a direction orthogonal to the optical axis based on the detection result. The positioning method, wherein the mark is moved to a position near the optical axis of the detection optical system, and after the relative movement, the position of the mark is detected again.