JPH09101115A - Image measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement of an object having the same patterns shifted right rightward and leftward and/or toward and rearward in the same arrangement in a short time. SOLUTION: This device having an X-Y stage 43 is provided with two image measuring heads 47, 49 having an optical axis perpendicular to the moving plane of the stage 43, a computing unit (host computer) determining the size and form of an object to be measured according to the relative positions of the heads 47, 49 the measurement results obtained by the respective image measuring heads and the moving quantity of the stage 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image measuring device, and more particularly to an image measuring device suitable for measuring the size and shape of a test object in which a large number of identical patterns are arranged in the same array on the left and right. .

[0002]

2. Description of the Related Art An example of a conventional image measuring device is shown in FIGS. FIG. 7 shows an XY stage type image measuring device, and FIG. 8 shows a fixed bridge type image measuring device. FIG.
In the above apparatus, the image measurement head 14 observes an object to be inspected, which is placed on the XY stage 12, and in which the object plate 12a is movable in a horizontal plane. An arbitrary part on the object can be observed by the movement of the XY stage. In the apparatus of FIG. 8, the stage 22 moves only in the Y direction and the image measuring head 25 moves in the X direction. Thereby, an arbitrary part of the test object can be observed. The image measuring heads 14 and 25 have a built-in image forming optical system and an image pickup device, and obtain a TV image of a test object. By subjecting the TV image to image processing, the shape and size of the pattern in the screen and the position of the pattern in the screen are obtained. The size and shape of the entire test object are obtained by adding the amount of movement of the stage and the image measuring head to the measurement result.

A typical substrate to be measured by an image measuring device is a liquid crystal substrate. In order to increase the productivity and reduce the product price of the substrate, a multi-cavity method is used. That is, this is a method in which a plurality of patterns required as products are arranged and manufactured on one large-sized substrate, and finally each pattern is divided and separated to obtain a finished product. Here, each pattern is the same, and the measurement points for inspection and measurement are also the same. Further, each pattern is regularly arranged, and the number of divisions is typically 2, 4, 6, 8, etc., and the left and right are arranged in the same arrangement.

[0004]

In the measurement by the above-mentioned conventional apparatus for such an object to be inspected, all the measurement target points must be sequentially scanned, and it takes a lot of time for the measurement. Conventionally, shortening of measurement time has been achieved by speeding up the stage and shortening image processing time, but there is a limit.
Further, there has been a problem that a large amount of development cost and time are required for further speeding up, and use of expensive materials and parts is required, so that the product becomes expensive.

[0005] The present invention has been made in view of this point,
The purpose is to significantly reduce the measurement time, improve the throughput, and reduce the product price.

[0006]

In order to achieve the above object,
According to the invention of claim 1, in the image measuring device having an XY stage, two image measuring heads having an optical axis perpendicular to a moving plane of the stage, relative positions of the two image measuring heads, and individual image measuring heads. An arithmetic unit (host computer referred to in the embodiments) for determining the size and shape of the object to be inspected based on the measurement result obtained in step 1 and the amount of movement of the stage.

According to a second aspect of the invention, in the first aspect of the invention, the distance between the two image measuring heads is changeable. According to the invention of claim 3, in the invention of claim 1, 2
One of the two image measuring heads was fixed, and the other was movable. In the invention of any one of claims 1 to 3, it is preferable that the two image measuring heads are arranged on a straight line parallel to one of the moving directions of the stage (the invention of claim 4).

[0008]

1 is a perspective view of a measuring unit 40 (see FIG. 2) according to a first embodiment of the present invention. FIG. 2 is a block diagram showing the overall configuration of the same embodiment. Base 4
The XY stage 43 is attached to 2. The XY stage 43 has a structure in which the mounting plate 43a is movable in a horizontal plane (in the XY plane). The structure is, for example, the middle plate 43b.
Moves along a guide 42a provided on the base 42 in the Y-axis direction, and the mounting plate 43a moves along a guide (not shown) provided on the upper surface of the middle plate 43b in the X-axis direction. This movement is performed by driving a motor by a driving mechanism (not shown) incorporated inside. As a result, the mounting plate 43
The motor a is driven in the XY plane. Controller 1
Reference numeral 02 denotes the position information of the XY stage 43 obtained from the amount of movement of the mounting plate 43a detected by two sets of position detectors attached to the XY stage 43, for example, a linear encoder (not shown), to the host computer 101. To do. The motor is driven by the controller 102 based on a command from the host computer 101.

An X guide 45 is provided in parallel with the X direction of the XY stage 43 on the support portions 44 provided on the left and right sides of the central portion of the base 42. A fixed image measuring head 47 is installed on the X guide 45 via a fixing member 46. Further, a moving image measuring head 49 is provided on the X guide 45.
Also via the carriage 48 by a drive device (not shown)
It is installed so that it can move in any direction.

The amount of movement is detected by a position detector (not shown) attached to the moving image measuring head, for example, a linear encoder, and read by the host computer 101. The host computer 101 calculates and calculates the relative position (spacing) of the two image measuring heads. As will be described later, since the measurement range is divided and the two image measuring heads share the measurement, the moving image measuring head does not need to be able to move the full stroke of the X guide.

The two image measuring heads 47 and 49 are respectively
It has a built-in imaging optical system and an image pickup element, and obtains a TV image of a test object. Each TV image is the first image processing device 103,
And the second image processing device 104, and the respective image processing devices perform image processing to obtain the shape dimensions of the in-screen pattern and the position of the pattern in the screen. Based on the measurement result, the amount of movement of the stage, and the relative position of the two image measuring heads, the size and shape of the entire test object can be obtained.

Next, the procedure for measuring the test object of FIG. 3 using the apparatus of the present invention will be described. The same six patterns 32a to 32f are arranged on the substrate 31 in the same arrangement on the left and right. Two measurement points 33a to 33l are set for one pattern, and are set at the same point in each pattern. First, as a measurement preparation, the moving image measuring head 49
Is moved so that the distance 50 between the fixed image measuring head 46 and the pattern distance 34 on the substrate matches. In the image measurement, if the measurement point is included in the screen, the position of the measurement point in the screen and the position of the stage and / or the image measurement head are processed by the host computer to obtain correct position coordinates. Does not have to exactly match the pattern interval.

When the measurement is started, the host computer 1
The host computer 101 outputs a drive command of the stage 43 to the controller based on the position information of the measurement position of the object stored in advance in 01. By this drive command, the controller 102 drives the stage 43 so that the measuring point 33g comes to the position of the fixed image measuring head 47. Then, the first image measuring device 103 takes in an image including the measurement point 33g based on a command from the host computer 101, and performs image processing on the image to obtain the shape dimension of the measurement point 33g and the position within the screen. . Based on this measurement result, the movement amount of the stage 43, and the relative positions of the two image measurement heads 47 and 49,
The host computer 101 determines the shape and size of the test object. Hereinafter, the measurement of each point is performed by the same procedure, but it will be simply referred to as measurement.

When the measuring point 33g is at the position of the fixed image measuring head 47, the moving image measuring head 49 is at the position of the measuring point 33a. Therefore, at the same time when the measuring point 33g is measured, the measuring point 33g is moved without moving the stage. Weigh 33 g. The image captured by the moving image measuring head 49 is processed by the second image processing device 104.

Next, the stage is moved so that the measuring point 33h is below the fixed image measuring head 47 (1 in FIG. 4; moving 1), and this is measured. By this movement of the stage, the measurement point by the moving image measuring head 49 moves from 33a to 33b (1 'in FIG. 4; movement 1'). Therefore, at the same time as measuring the measurement point 33h,
The moving image measuring head 49 measures this point 33b without moving the stage. Repeat this step,
The fixed image measuring head 47 measures points 33i to 33l.
Simultaneously, the moving image measuring head 49 sequentially measures the measurement points 33c to 33f and ends the measurement.

The stage movement during this period is five times 1 and 1 '(movement 1) to 5 and 5' (movement 5) shown in FIG. Here, as described above, the movement 1 and the movement 1'-
The movement 5 and the movement 5'are simultaneously performed by one stage movement. When the same measurement is performed by the conventional image measuring machine, as shown by 1 to 11 in FIG. 5, the stage needs to be moved 11 times, and the total movement distance is twice or more.
According to the device of the present invention, the measurement time is significantly shortened as compared with the conventional device.

In addition, as shown in FIG.
When measuring the substrate 61 in which 65f is not arranged on the left and right, the stage may be moved so that the measurement points 65a to 65f are located below either the fixed image measuring head 47 or the moving image measuring head 49, whichever is closer. For example, the substrate 61
Measurement points 65a to 65 on the 62 side of the center line 64 of
c is measured by the moving image measuring head 49, and measurement points 65d to 65f on the 63 side are measured by the fixed image measuring head 47. In this way, the number of movements is the same as in the prior art method, but the total movement distance is shortened and the measurement time is shortened.

Since the moving image measuring head 49 does not need to be moved during the measurement once the position has been set in preparation for the measurement, a high-performance device such as a stage driving device is not necessary, and the device is inexpensive. Or a manual device will do. Further, if the object to be inspected is limited, the moving image measuring head may be fixed according to the pattern interval of the object to be inspected. It goes without saying that the two image processing heads may be movable together.

Further, although two image processing devices are used in the above-mentioned embodiment, an image selector which receives images from two image measuring heads, selects one of the images, and sends it to the image processing device. If provided, the number of image processing devices can be one. Further, in the above-described embodiment, the two image measuring heads are arranged parallel to the X axis, but if the relative position (difference between X and Y coordinates) of the two image measuring heads is known, X,
The arrangement may be offset in both Y directions. The relative position of the two image measuring heads can be obtained from the measurement result obtained by measuring the same position on the test object with both the fixed measuring head and the moving measuring head.

In the above description, the liquid crystal substrate is taken as the object to be inspected, but the application of the device of the present invention is effective as long as it is an object of another type and the pattern arrangement has the same characteristics. Needless to say.

[0021]

As described above, according to the present invention, the measurement time can be greatly shortened for the test object having the pattern arrangement of the left and right arrays. Even for a test object having a pattern arrangement that is not the same arrangement, it is possible to considerably reduce the measurement time by properly using the two image measurement heads and devising the measurement sequence so that the movement amount of the stage is minimized. Furthermore, the stroke in the direction of arrangement of the stages is 1/2 of the dimension of the test object in that direction.
Therefore, the guide surface of the stage can be easily processed, and the stage accuracy can be improved and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a measuring unit of an apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an entire apparatus according to an embodiment of the present invention.

FIG. 3 is a plan view showing a schematic arrangement of a liquid crystal substrate as an example of a test object.

FIG. 4 is an explanatory diagram showing a measurement procedure of the test object of FIG. 3 according to the embodiment of the present invention.

5 is an explanatory diagram showing a measurement procedure of the test object of FIG. 3 according to a conventional technique.

FIG. 6 is a plan view showing another measurement point corresponding to another test object.

FIG. 7 is a perspective view of a measuring unit of a conventional XY stage type image measuring device.

FIG. 8 is a perspective view of a measuring unit of a conventional fixed bridge type image measuring device.

[Explanation of symbols]

 12, 43 ... XY stage 14, 25 ... Image measuring head 47 ... Fixed image measuring head 49 .. Moving image measuring head 45 .. X guide 31, 61 ... substrate 32a-32e pattern 33a-331, 65a-65f measurement point 101 host computer 102 ... ... Controller 103 ... First image processing device 104 ... Second image processing device

Claims (4)

[Claims] 1. In an image measuring apparatus having an XY stage, two image measuring heads each having an optical axis perpendicular to a moving plane of the stage, relative positions of the two image measuring heads, and individual image measurement. An image measuring device, comprising: a calculation device that determines the size and shape of the test object based on the measurement result obtained by the head and the amount of movement of the stage. 2. The image measuring device according to claim 1, wherein a distance between the two image measuring heads can be changed. 3. The image measuring device according to claim 2, wherein one of the two image measuring heads is fixed and the other is movable. 4. The image measuring device according to claim 1, wherein the two image measuring heads are arranged on a straight line parallel to one of the XY directions.