JP2000298004A - Position measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position measuring instrument which can collectively measure the positions of a plurality of alignment marks on a work. SOLUTION: A position measuring instrument separately and individually measures the X and Y coordinate positions of alignment marks by performing image synthesization by means of an image guide 60 and processing image signals of one screen quantity from an image pick-up element 72 by means of an image processor 80. Since the measuring instrument can collectively measure the positions of the alignment marks, the positions of the alignment marks can be measured quickly even when the number of the marks is a plural number and the treatment throughput of a laser beam annealing device can be improved.

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 for measuring the position of a measuring object for the purpose of, for example, aligning the measuring object.

[0002]

2. Description of the Related Art In a laser processing apparatus, a workpiece to be processed is preliminarily positioned with respect to an irradiation optical system for irradiating a processing laser beam.

As a laser processing apparatus, for example, there is a laser annealing apparatus for heating an amorphous semiconductor thin film formed on a glass substrate with a laser to make it polycrystalline. In such a laser annealing apparatus, a line-shaped or spot-shaped beam from an irradiation optical system may be scanned on a glass substrate. In such a scanning, a position measuring device incorporated in the laser annealing apparatus is used. The position of the glass substrate placed on the stage is detected with high accuracy using
Alignment between the irradiation optical system and the glass substrate is performed.

In a conventional position measuring device, a plurality of positioning marks formed on the surface of a work are sequentially read by a CCD camera in order to accurately measure the position of a work such as a glass substrate, and image processing necessary for the read image data is performed. To obtain a position detection signal for each positioning mark.

[0005]

However, in the position measuring device as described above, for each of the plurality of positioning marks on the work, the stage is moved individually so that the marks enter the field of view of the CCD camera. Since the position is measured, quick position measurement and alignment are difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a position measuring device capable of collectively measuring a plurality of positioning marks on a work.

[0007]

In order to solve the above-mentioned problems, a position measuring apparatus according to the present invention has a pair of incident ends on which image light from two different points on a stage is incident.
An image guide that combines a pair of image lights from a pair of incident ends so that the pair of image lights overlap, and transmits the combined image light to an emission end, and a combined image guide that is emitted from the emission end of the image guide. Imaging means for converting image light into an image signal;
Signal processing means for separating and detecting predetermined position information contained in a pair of image light before combining from the image signal converted by the imaging means.

In the above position measuring device, the image guide combines the pair of image lights from the pair of incident ends such that the pair of image lights overlap, and the signal processing means converts the image signal converted by the imaging means into an uncomposed image signal. Since the predetermined position information included in the pair of image lights is separately detected, if a pair of positioning marks are formed corresponding to the two different points on the surface of the measurement object arranged on the stage. The position information can be collectively detected for these positioning marks. Therefore, in such a position measuring device, quick position measurement can be performed for a plurality of positioning marks, and the throughput of processing by a laser processing device or the like that performs alignment using such position measurement results can be improved.

When the above-described position measuring device is used, special electronic equipment such as image combining by superimposition processing or image combining using an image processing device is not required, and a simple and inexpensive image combining device is used. Compositing becomes possible. Also, there is more freedom in the arrangement of the images to be combined (that is, the optical axis) as compared to the image combination using a half mirror.

The above-described position measuring device is suitably incorporated in, for example, a laser annealing device. The laser annealing apparatus includes a light source that generates a laser beam for heating an amorphous semiconductor thin film formed on a glass substrate, an irradiation optical system that guides the laser beam into a line or a spot on the substrate, and an object to be measured. And a driving means for moving the stage on which the glass substrate is mounted relative to a pair of incident ends provided on the irradiation optical system and the image guide. In this case, since the glass substrate can be quickly aligned with the irradiation optical system by the position measuring device, the laser annealing process becomes faster, and the throughput of manufacturing the semiconductor thin film can be increased.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a position measuring device according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a diagram conceptually illustrating the structure of a laser annealing device incorporating the position measuring device of the embodiment. The laser annealing apparatus includes a stage 10 on which a work W, which is a glass plate having a semiconductor thin film such as amorphous Si formed on the upper surface, is placed and can be smoothly moved three-dimensionally.
A laser light source 20 for generating an excimer laser or other laser light AL for heating a semiconductor thin film on the work W, and irradiation optics for making the laser light AL linear or spot-like and incident on the work W with a predetermined illuminance The system 30, a stage driving device 40 that is a driving unit that relatively moves the stage 10 on which the work W is mounted with respect to the irradiation optical system 30, and the like, and an operation of each unit of the entire laser annealing apparatus. And a main control device 85 for controlling the operation.

Further, this laser annealing apparatus is a position measuring device, in addition to the stage 10 and the stage driving device 40, a moving amount measuring device for detecting the moving amount of the stage 10 as optical information or electrical information. 50 and
An image guide 60 for simultaneously reading and combining images of a pair of alignment marks formed at two different points on a workpiece W as a measurement target, and a combined image light emitted from an emission end of the image guide 60. A CCD camera 70 for projecting an image and converting the projected image light into an image signal; and an image processing device 8 as signal processing means for performing appropriate signal processing on the image signal output from the CCD camera 70
0.

The image guide 60 is a bundle of glass fibers, and includes an output-side combining section 61 connected to the CCD camera 70, and a pair of input-side branching sections 62 and 63 branched from the combining section 61. It is a special image guide consisting of Incident ends 62a, 6 of a pair of branch portions 62, 63
Reference numeral 3a faces the work W via the imaging lenses 64a and 65a provided on the holders 64 and 65, respectively. These imaging lenses 64a, 65a are
The image of the alignment mark of the workpiece W is projected on the end face of the optical fiber a. On the other hand, the combining unit 61
The emission end 61a of the
And an image pickup device 72 as image pickup means such as a CCD. In the field of view of the image sensor 72, the two branch portions 6
Image light from a region including a pair of alignment marks on the work W facing the incident ends 62a and 63a of
While being guided by the image guide 60, the images are combined and enlarged or reduced as image light and projected. Note that, of the holders 64 and 65 arranged opposite to the pair of alignment marks on the work W, one of the holders 65 is provided.
Is provided with a fine movement device 68 capable of detecting the amount of movement, and the two holders 64, 6 according to the type of the work W and the like.
The interval of 5 can be appropriately adjusted from the main control device 85 side.

FIG. 2 is a view showing an example of the shape and arrangement of positioning marks, ie, alignment marks, formed on the surface of the work W placed on the stage 10. As shown in FIG. The illustrated alignment marks M1 and M2 are both binary patterns of light and dark. The first alignment mark M1 is formed at one of the four corners of the work W, and the second alignment mark M2 is formed at the other of the four corners of the work W. As described above, the first and second alignment marks M1 and M2 are formed at two places on the workpiece W.
This is for detecting not only the position of the work W but also the rotation of the work W. That is, the first and second alignment marks M
1. By measuring the position of M2, the XY coordinates of the two reference points on the work W can be known, and the alignment for moving the work W to an appropriate position after correcting the rotation posture of the work W about the Z axis is achieved. Will be possible.

FIG. 3 is a schematic diagram illustrating the structure of the image guide 60. Each branching unit 6 branched from the synthesizing unit 61
The incident ends 62a and 63a of the reference numerals 2 and 63 are arranged to face a pair of alignment marks M1 and M2 formed on the work W, respectively. Each alignment mark M1, M2
And images IM1 and IM2 around the imaging lens 64a,
The light is projected onto the incident ends 62a and 63a by 65a. The fibers constituting the two branch portions 62 and 63 are combined so as to be inserted alternately between them, and are combined.
Is formed. For this reason, the emission end 61a of the combining section 61
A composite image CI obtained by combining the two alignment marks M1 and M2 is projected by the imaging lens 71 onto the field of view of the image sensor 72 arranged opposite to the image sensor 72. This composite image CI includes alignment marks M1 'and M2' corresponding to the alignment marks M1 and M2 before the composition. In the drawings, the fiber constituting one branching section 62 is represented by a white circle and the fiber constituting the other branching section 63 is represented by a black circle, but this is for convenience of explanation.

FIG. 4A is a partially enlarged sectional view showing the arrangement of the fibers constituting the branching section 62, and FIG.
FIG. 4 is a partially enlarged cross-sectional view showing the arrangement of the fibers constituting the branching unit 63, and FIG. 4C is a partially enlarged sectional view showing the arrangement of the fibers constituting the synthesizing unit 61. FIG.
As is clear from FIG. 4A and FIG.
The manner of assembling the fibers 2 and 63 is the same. FIG. 4 (c)
As is clear from FIG. 2, the fiber constituting the combining unit 61 is a fiber obtained by assembling the fibers constituting both the branching units 62 and 63 alternately in the X direction. Are doubled, and the dimension in the X direction is similarly expanded even when attention is paid to the fiber from the branch portion 63. In the drawing, reference numerals A1 to A5 and B1 to B5 indicate the identities of the fibers constituting the branching unit 62.

FIG. 5 is a diagram specifically illustrating position detection using an alignment mark. FIG. 5A shows the composite image CI of FIG. 3, and FIG.
6 is a graph showing the integrated light amount in the Y direction of the composite image CI as a function of the X coordinate. This integrated light amount is obtained by subjecting the composite image CI to image processing by the image processing device 80. That is, the composite image CI including the alignment marks M1 'and M2' is projected onto the image sensor 72 of the CCD camera 70. Since the output of the image signal of the image sensor 72 is data in units of pixels, the image processing device 80 By adding all these image signals in the Y direction for each X coordinate,
A distribution as shown in FIG. 5B is obtained. As is clear from the graph, each of the alignment marks M1 'and M2' after the synthesis.
A peak appears at a portion corresponding to the vertical bar of the cross. When this distribution is processed with an appropriate threshold value TH, two sets of X coordinates (X1, X2) and (X3, X4) corresponding to a pair of edges of a vertical bar extending in the Y direction of each alignment mark M1 ', M2' are obtained. The two sets of X coordinates (X1, X2) and (X3, X4) are averaged to obtain the alignment marks M1 'and M2'.
Can be determined.

The pixel width of the image sensor 72 and the stage 1
A precise correspondence is previously determined between the distance X and the distance above the distance X in consideration of the enlargement and reduction ratios of the image guide 60 and the like, and the X of the center of each alignment mark M1 ', M2' is determined.
From the coordinates (coordinates on the composite image CI), the X coordinates of the actual alignment marks M1 and M2 can be accurately determined.

The above is a description of a pair of alignment marks M1,
Although the description has been given of the case where the X coordinate of M2 is determined, the same applies to the determination of the Y coordinate of the alignment marks M1 and M2. That is, by adding the image signal from the image sensor 72 in the X direction for each Y coordinate in the image processing device 80, a distribution similar to that shown in FIG. 5B is obtained. M1 ', M2', that is, the Y coordinate of the center of each alignment mark M1, M2 can be determined.

Hereinafter, the operation of the laser annealing apparatus of this embodiment will be described. First, the work W is transported and placed on the stage 10 of the laser annealing apparatus. Next, the work W on the stage 10 is aligned with the irradiation optical system 30 that guides the laser light AL for annealing. next,
While appropriately moving the stage 10 with respect to the irradiation optical system 30, the laser light AL from the laser light source 20 is incident on the workpiece W in a line shape or a spot shape. An amorphous semiconductor thin film is formed on the work W, and the amorphous semiconductor is annealed and recrystallized by irradiation with the laser beam AL, so that a semiconductor thin film having excellent electric characteristics can be provided. .

When aligning the work W on the stage 10 with respect to the irradiation optical system 30, a position measuring device is used. That is, the stage 10 is appropriately moved by the stage driving device 40, and each of the alignment marks M1, M2 is photographed by the CCD camera 70 (Step S).
1). Since the position of the work W on the stage 10 is within a certain conveyance accuracy range, the stage 10 is appropriately moved with respect to the image guide 60 and the holders 64 and 65 so that both alignments can be performed within the image field of the image sensor 72. Mark M
1, the alignment marks M1 'and M2' obtained by synthesizing M2 can be captured. For example, if the positions of the two alignment marks M1 and M2 on the work W are input in advance to the main controller 85 and stored in the main controller 85, based on these position data, the stage 10 can be simply moved as appropriate, and 7
It is ensured that the alignment marks M1 'and M2' are almost certainly included in the field of view 2.

Next, for each of the alignment marks M1 and M2, the image processing device 80 processes an image signal for one screen from the image sensor 72 by the method shown in FIG. And individually measure (step S2).

Next, the work W is aligned with the irradiation optical system 30 based on the precise coordinate measurement results of the first and second alignment marks M1 and M2 obtained in step S2 (step S3). Specifically, the position and rotation of the workpiece W are obtained based on the coordinate measurement values of the first and second alignment marks M1 and M2 based on the irradiation optical system 30,
Based on this result, the work W is arranged at a position required at the start of laser annealing with a necessary rotation posture.

Next, a laser beam AL such as a laser spot or a laser line irradiated from the irradiation optical system 30 is scanned on the work W by using the stage driving device 40 and the movement amount measuring device 50. Is recrystallized to sequentially form a polycrystalline thin film on the work W. At this time, by scanning the stage 10 in the X direction or the Y direction by the stage driving device 40 while observing the movement amount by the movement amount measuring device 50, laser scanning becomes possible. Also, by providing the irradiation optical system 30 with a scanning function, for example, by providing a slit that moves inside, the laser can be scanned in another direction.

According to the apparatus described above, it is possible to collectively measure the position of each of the alignment marks M1 and M2. Therefore, a plurality of alignment marks M1, M2
Even in this case, quick position measurement becomes possible, and the processing throughput of the laser annealing apparatus can be improved.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment. For example, in the above embodiment, the sizes of the pair of alignment marks M1 and M2 are equal, but the sizes of the alignment marks need not necessarily be equal. For example, one alignment mark may have a large size for search alignment and the other alignment mark may have a small size for fine alignment, depending on applications such as detection accuracy.

FIG. 6 shows a case where a pair of alignment marks M3 and M4 having different sizes are formed on the work W.
In this case, the large cross alignment mark M3 is used for search alignment, and the small cross alignment mark M4 is used for fine alignment. here,
The image of the alignment mark M4 projected on the incident end 63a of the other branch 63 is
The images are synthesized in a state that is larger than the image of the alignment mark M3 projected on a. That is, the imaging lens 65
The projection magnification by a is larger than the projection magnification by the imaging lens 64a.

The position measuring method in this case will be briefly described. First, the position of the alignment mark M3 is measured to determine the coordinates of the alignment mark M3. Such position measurement is the same as in the case of the alignment mark M1. In this state, it is conceivable that the alignment mark M4 does not enter the image field of the image sensor 72. However, if the center of each alignment mark M3, M4 is aligned with the center of the incident end 62a, 63a of each branch portion 62, 63 and the optical axis of each imaging lens 64a, 65b, the alignment mark M3 can be obtained. Based on the given coordinates,
By moving the alignment mark M3 to the center of the field, the alignment mark M4 can be moved almost exactly to the center of the field of the image sensor 72.

If the alignment mark M4 can be positioned substantially at the center of the field of view of the image sensor 72, the above-described position detection method applied to the alignment mark M3 can be applied to the position detection of the alignment mark M4. Therefore, the XY coordinates of the alignment mark M4 can be determined. In this case, the image of the alignment mark M4 projected on the image sensor 72 has a large enlargement ratio as described above and detects the image of the work W in finer pixel units, so that more precise position detection is possible.

In the above embodiment, the contours of the alignment marks M1 to M4 are not limited to crosses, but may be, for example, annular marks. It can be adjusted appropriately according to the size of the field and the like. Further, the light / dark contrast of the alignment marks M1 to M4 can be appropriately set according to required accuracy, workability of the work W, surface color, and the like. Further, it goes without saying that the algorithm for measuring the positions of the alignment marks M1 to M4 can be appropriately changed according to the shape of the alignment marks and the like.

The image guide 60 is not limited to the structure shown in FIGS. 1 and 3, but may be a bundle of three or more image guides. In this case, three or more alignment marks are provided. Can be measured simultaneously. Further, the synthesizing unit 61 constituting the image guide 60
And how to bundle optical fibers in the branch portions 62 and 63,
Any arrangement in which the image lights from the branching units 62 and 63 are alternately arranged (alternately arranged in an order) such that the image lights overlap in the combining unit 61 is possible.

Further, the above-described position measuring device uses the laser light A
Although the semiconductor layer on the work W is annealed using L, if the structures of the laser light source 20, the irradiation optical system 30 and the like are appropriately changed, the purpose is not only for annealing of the semiconductor material but also for cutting and welding. Pulse laser processing apparatus.

[0034]

As is apparent from the above description, according to the position measuring apparatus of the present invention, the image guide combines the pair of image lights from the pair of incident ends so that the pair of image lights overlap. Since the signal processing means separates and detects predetermined position information included in the pair of image light before synthesis from the image signal converted by the imaging means, the above-mentioned different position information is provided on the surface of the measurement target placed on the stage. If a pair of positioning marks are formed corresponding to the two points, the position information can be collectively detected for these positioning marks.
Therefore, in such a position measuring device, quick position measurement can be performed for a plurality of positioning marks, and the throughput of processing by a laser processing device or the like that performs alignment using such position measurement results can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a laser annealing apparatus incorporating a position measuring device according to an embodiment.

FIG. 2 is a diagram illustrating a position measurement mark on a work placed on a stage of the apparatus of FIG.

FIG. 3 is a diagram illustrating a structure of an image guide for forming a plurality of position measurement marks into a composite image.

4 (a), (b) and (c) are views for explaining how to assemble the fibers constituting the image guide of FIG. 3;

5A is a graph corresponding to an image of a position measurement mark synthesized by an image guide, and FIG. 5B is a graph illustrating the integrated luminance of the image.

FIG. 6 is a diagram illustrating a modification of the position measurement mark shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stage 20 Laser light source 30 Irradiation optical system 40 Stage drive device 50 Movement amount measuring device 60 Image guide 61 Synthesizing part 61a Outgoing end 62,63 Each branch part 62,63 Branch part 62a, 3a Input end 63 Branch part 64,65 Holder 64a, 65a Imaging lens 70 CCD camera 71 Imaging lens 72 Image sensor 80 Image processing device 85 Main control device M1, M2 Alignment mark

Claims (1)

[Claims] An image processing apparatus includes: a pair of incident ends on which image light from two different points on a stage is incident; and combining a pair of image lights from the pair of incident ends such that the pair of image lights overlap. An image guide for transmitting the combined image light to an emission end; an imaging unit for converting the combined image light emitted from the emission end of the image guide into an image signal; and the image converted by the imaging unit And a signal processing unit for separating and detecting predetermined position information included in the pair of image light before combining from the signal.