JP2006184085A - Dimension measuring method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a measuring time by correcting efficiently a dimension measuring position. <P>SOLUTION: As for correction of the measuring position, measurement is performed after performing position movement in order to correct a position deviation, only when the position deviation of a measuring spot on a measuring object fixed to a measuring device is large. When the position deviation of the measuring spot is small, measurement is performed without correcting the position deviation. A tolerance of the position deviation is determined beforehand corresponding to the difference of a measuring condition such as a measuring magnification or the position of the measuring spot in a measuring image, and the position deviation of the measuring spot on the measuring object such as a glass substrate to be measured is detected. When the position deviation is below the tolerance, measurement is performed as it is, and only when the position deviation is over the tolerance, measurement is performed after correcting the position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dimension measuring apparatus that takes an image of a measurement location of an object to be measured with an imaging apparatus, and performs image processing on the captured image for inspection and measurement, and more particularly to a method for efficiently automatically correcting a measurement position. Involved.

  The dimension measuring device is a device that measures the pattern width and pattern interval of a TFT (Thin Film Transistor) on a substrate (for example, an LCD (Liquid Crystal Display) substrate, hereinafter referred to as a liquid crystal panel) and a semiconductor mask. The dimension measuring device is obtained, for example, by magnifying a pattern image obtained by irradiating a pattern formed on a transparent glass substrate (sample) with a microscope and capturing the image with a CCD (Charge Coupled Device) camera. The resulting pattern image is image processed and the dimensions are measured.

In recent years, demand for TFT (Thin Film Transistor) liquid crystal panels has been increasing. Accordingly, in the manufacturing process of the liquid crystal panel, the production efficiency is improved by increasing the size of the glass substrate for liquid crystal and increasing the number of liquid crystal panels (number of products) that can be obtained in one liquid crystal glass substrate.
Therefore, pattern exposure errors (positional deviation) on the glass substrate generally tend to increase as the liquid crystal glass substrate becomes larger.
As a result of the increased position shift, the inspection device will move the XY stage to image the specified measurement position, and the pattern position on the glass substrate will be shifted. There may be a situation where a part of the measurement target necessary for image processing protrudes.

  The misregistration occurs for each glass substrate to be exposed and for each exposure process due to, for example, a dimensional error of the glass substrate or a pattern exposure error on the glass substrate. In order to correct the misalignment of the measurement area such as the pattern on the glass substrate, the pattern displacement amount is detected by a method such as pattern recognition, and the dimension after moving the XY stage to correct the misalignment. Thus, stable measurement is realized (for example, refer to Patent Document 1 or Patent Document 2). For this reason, the measurement time takes much time for correcting the positional deviation.

JP 2000-28336 A JP 2004-184411 A

In the above-described prior art, even when the pattern position shift is small, measurement is always performed after the XY stage is moved (hereinafter referred to as correction movement) in order to correct the shift amount. For this reason, the measurement time takes much time to correct the shift amount.
An object of the present invention is to provide a measurement method and a measurement apparatus with a short measurement time by efficiently correcting the measurement position.

In order to achieve the above object, the dimension measuring method and the dimension measuring apparatus of the present invention reduce the measurement time by efficiently correcting the measurement position.
That is, the measurement method of the measurement apparatus of the present invention includes a microscope, an imaging unit that receives incident light from a measurement target location of the measurement target object through the microscope and outputs it as a video signal, and the dimensions of the measurement target from the video signal. An image processing unit for measuring a position, and a moving means for moving at least one of the measurement object or the imaging unit in order to move the measurement location of the measurement object to a desired visual field position of the microscope, An image processing unit controls a microscope, an imaging unit, and a moving unit on the basis of inspection information set in advance, and in a measuring method of a measuring apparatus that measures the size and position of a subject part, A step of moving to a position, a step of detecting a shift amount between the moved visual field position and the position of the inspection information, a step of determining whether the shift amount is larger or smaller than a predetermined allowable value, and a determination step Therefore, if greater than displacement amount permissible value, and a step of moving correcting the microscope field position according to the displacement amount is to measure the size or position of the object point.

  Further, the measuring method of the measuring apparatus according to one aspect of the present invention includes a microscope, an imaging unit that receives incident light from a measurement target location of the measurement target object through the microscope and outputs it as a video signal, and a measurement target location from the video signal. An image processing unit that measures the size and position of the object, and a moving unit that moves at least one of the object to be measured or the imaging unit in order to move the measurement location of the object to be measured to a desired visual field position of the microscope; In the measuring method of the measuring apparatus for measuring the size and position of the subject part by controlling the microscope, the imaging unit, and the moving unit based on the inspection information set in advance, A step of moving the measurement location to the visual field position, a step of detecting a deviation amount between the moved visual field position and the position of the inspection information, a step of determining whether the deviation amount is larger or smaller than a predetermined allowable value, The constant step, if smaller than the allowable value is a deviation, which measures the size or position of the object point.

  In addition, the dimension measuring method according to one aspect of the present invention automatically calculates an allowable value at the time of setting a measurement location in the visual field position when setting inspection information.

  In addition, the measuring apparatus of the present invention includes a microscope, an imaging unit that receives incident light from a measurement location of an object to be measured through the microscope and outputs it as a video signal, and measures the size and position of the measurement location from the video signal. An image processing unit, and a moving means for moving at least one of the measurement object or the imaging unit to move a measurement location of the measurement object to a desired visual field position of the microscope, and the image processing unit Means for moving the measured location to the visual field position in the measuring apparatus for measuring the size and position of the subject location by controlling the microscope, the imaging unit, and the moving means based on the inspection information set in advance; Means for detecting a deviation amount between the moved visual field position and the position of the inspection information, a means for judging whether the deviation amount is larger or smaller than a predetermined allowable value, and a determination step, wherein the deviation amount is larger than the allowable value. Lever, and means for moving correcting the microscope field position according to the displacement amount is to measure the size or position of the object point.

As described above, the measurement position is automatically corrected only when the pattern position is shifted so that measurement is impossible, and accurate automatic measurement is possible without extending the measurement time.
Even when measurement is impossible due to an incorrect setting value, the function can be continued by using the function for automatically correcting the setting, so that the burden on the user is reduced.
Further, even if a high-speed XY stage or an XY stage with inferior movement accuracy is used, stable measurement can be performed, so that the degree of freedom in system construction is improved.

  The dimension measuring method and the dimension measuring apparatus according to the present invention reduce the measurement time by efficiently correcting the measurement position. For example, the measurement position is corrected after moving to correct the positional deviation only when the positional deviation (for example, pattern) of the measurement target of the measurement target fixed to the measurement apparatus is large. However, when the positional deviation of the measurement location is small, the measurement is performed without correcting the positional deviation (that is, without performing correction movement).

  In addition, the measuring method and measuring apparatus of the present invention is a glass that preliminarily sets an allowable value of a positional deviation amount corresponding to a difference in measurement conditions such as a measurement magnification and a position of a measurement location in a measurement image. Detects the amount of misalignment at the location to be measured on the object to be measured, such as a board, and if the amount of misalignment is less than the tolerance, measure it as it is. Measure from

That is, the dimension measuring method and the dimension measuring apparatus of the present invention are a measuring apparatus and a measuring method for performing image processing for dimension measurement or the like in combination with a microscope and an area sensor such as a television camera that captures an enlarged subject image by the microscope. An automatic correction function of the measurement position, which is a means for stabilizing the automatic measurement process, is efficiently performed.
As a result, the measurement position is automatically corrected only when there is a misalignment of the measurement site so that measurement is impossible, and when the misalignment is small, measurement is performed without correcting the measurement position. Accurate measurement is possible.

Furthermore, in the above measurement, even if the setting value (allowable deviation amount) is incorrect or measurement is impossible for some reason, it has a function that automatically corrects the setting. Since the measurement can be continued by changing the set value and operating the correction function, the burden on the user can be reduced.
In addition, even if a high-speed XY stage or an XY stage with inferior movement accuracy is used, stable measurement is possible, so the degree of freedom in constructing manufacturing systems and inspection systems including measurement devices is improved.

  An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. 1 is an object to be measured, 2 is a microscope, 3 is an objective lens, 2-1 is an optical axis of the microscope 2, 4 is an imaging unit, 5 is an image processing unit, 6 is an image processing monitor, 7 is an illumination unit, 7 -1 is a light guide that guides the illumination light output from the illumination unit 7 to the microscope 2, 8 is a device control unit, 9 is a device control monitor, 10 is a stage control unit, 11 is an XY stage, 12 is a Z stage, 1- 0 is the XY stage 11 base. The imaging unit 4 is a television camera such as a CCD (Charge Coupled Device) camera, for example. The device control unit 8 is, for example, a PC (Personal Computer).

  In FIG. 1, the XY stage 11 includes a sample stage for fixing the object 1 to be measured, and the object 1 to be measured, for example, one of the liquid crystal glass substrates is fixed to the sample stage. The XY stage 11 and the Z stage 12 are controlled by a control program stored in advance in the operator and the device control unit 8, and are in the X direction (one in the horizontal direction), the Y direction (the other one in the horizontal direction), and the Z direction ( Focusing and position control are performed by moving in a three-dimensional direction (vertical direction). The control program can take in a product-corresponding inspection program having inspection information according to the type of the object to be measured (product, etc.). Measure based on the inspection information necessary for each product such as value.

This inspection information can be registered in advance or can be arbitrarily changed by the operator immediately before the start of product measurement or even during the product measurement.
In the following description of the present invention, the measurement apparatus, the measurement method, or the measurement process is described. However, it is obvious that the measurement apparatus, the inspection method, or the inspection process may be used instead.

The microscope 2 enlarges the reflected light image within the field of view (field position) of the object 1 to be measured centered on the optical axis 2-1 of the microscope 2 with the objective lens 3 according to the measurement magnification. Is incident on. The imaging device 4 photoelectrically converts the incident reflected light image for each pixel and outputs the incident light image to the image processing unit 5 as a video signal.
The image processing unit 5 controls the illuminating unit 7 so that the brightness of the video signal becomes an appropriate value, and also measures the dimension of the measurement target (for example, the pattern line) from the luminance information of the video signal acquired by the imaging unit 4. Measure width, pattern interval) and position.

  In addition, the image processing unit 5 sends and receives signals to and from the operating unit for the operator to operate the measuring device, the illumination unit 7, the microscope 2, and the imaging unit 4, and receives information from them, or signals to them. Have the ability to send them and control them.

The image processing monitor 6 displays on the display screen the incident light image of the visual field position acquired by the imaging unit 4 and the measurement result.
The apparatus control unit 8 controls the image processing unit 5 and the stage control unit 10 in accordance with an operator instruction and a control program, and controls the XY stage 11 and the Z stage 12 in at least one of the X direction, the Y direction, and the Z direction. The visual field position is moved while being driven to perform measurement processing.

  The device control monitor 16 displays measurement position information, measurement results, etc. on its display screen. In many cases, the measurement result displayed on the image processing monitor 6 is, for example, data in the displayed image. However, the measurement result displayed on the apparatus control monitor 16 is, for example, for each object to be measured. The measurement results, coordinate data, measurement results corresponding to the measurement location, etc. are displayed in a list, for example.

In one embodiment of the apparatus according to the present invention, it is necessary to set (register) a measurement position on a glass substrate and a measurement point in a video signal acquired by imaging a visual field range including the measurement position as inspection information in advance. There is. Hereinafter, an image obtained by displaying a video signal obtained by imaging the visual field position on the display screen of the image processing monitor 6 is referred to as a measurement image.
With reference to FIG. 2, the matching area and the measurement location in the measurement image are described. FIG. 2 is a diagram for explaining an embodiment of the present invention, and is an example of a measurement image displayed on the display screen of the image processing monitor 6 of FIG. Reference numeral 20 is a measurement image, hatched lines 13 are patterns formed on a glass substrate, dotted frame 14 is a matching area, and solid line frames 15 and 16 are points to be measured. For example, the pattern contained in this frame The pattern width of 13 is measured as the line width. As a specific measurement algorithm, for example, a well-known technique such as the technique described in Paragraph 0017, FIG. 8, and FIG. At this time, the scanning range necessary for the actual measurement is, for example, when measuring the line width of the pattern 13 within the solid line frame 16 of the measurement site, in addition to the pattern 13, the peripheral portion is required. Therefore, the solid line frame 16 designates an area wider than the pattern 13.
Here, the intersection of the alternate long and short dash lines 21 and 22 is the point through which the optical axis 2-1 of the microscope 2 passes and is the center of the measurement image.

  In one embodiment of the apparatus according to the present invention, in order to measure the line width of the pattern at an arbitrary position of the pattern 13 in the measurement image, the operator designates the matching area 14, the measurement location 15 and the measurement position, etc. The image processing unit 5 sets inspection information such as those positions, and registers the measurement location 15 as a relative position with the matching area 14.

When an actual liquid crystal glass substrate is measured, there is a case where a pattern position shift occurs as shown in FIG. 3 due to a dimensional error or an exposure error of the liquid crystal glass substrate. FIG. 3 is a diagram for explaining an example of the measurement image according to the embodiment of the present invention, and is a diagram for explaining the measurement image when the position of the pattern that is the measurement location is shifted.
In the measurement image 30 of FIG. 3, the measurement location 15 can be measured, but the measurement location 16 cannot be measured because it does not entirely fit in the measurement image (image data cannot be acquired).

In the present invention, the image processing unit 5 performs the measurement process according to the flow shown in FIG. 4 in order to cope with the positional deviation of the pattern such as the measurement site 16 in FIG. FIG. 4 is a flowchart of the measurement process according to an embodiment of the present invention.
In FIG. 4, the object 1 to be measured is fixed to the XY stage 11 in advance, and the alignment of the object 1 to be measured is completed.

  In the measurement position moving step 401, the XY stage 11 and the Z stage 12 are moved in order to image the predetermined measurement position that has been set, and the objective is set so as to obtain imaging conditions such as magnification, illuminance, etc. registered in advance. The lens 3, the illumination unit 7, the imaging unit 4, and other necessary units are controlled. Next, the process of the measurement image acquisition step 402 is executed.

In the measurement image acquisition step 402, the imaging unit 4 acquires the measurement image, and then executes the processing of the matching step 403.
In the matching step 403, pattern matching processing with the matching area 14 is performed on the acquired measurement image, and the position of the matching area 14 is detected. Next, the pattern position deviation determination step 404 is executed.

In the pattern misalignment determination step 404, the misalignment between the position actually detected in the matching step 403 and the pre-registered position is calculated, and whether the pattern misalignment amount is larger or smaller than a predetermined value set in advance. judge.
If it is determined that the amount of positional deviation is small, the process of measurement step 406 is executed. If it is determined that the amount of positional deviation is large, the process of correction moving step 405 is executed.

In the correction movement step 405, the XY stage 11 is corrected and moved, and the process of the measurement image acquisition step 402 is executed.
Thereafter, the measurement image acquisition step 402, the matching step 403, and the pattern position deviation determination step 404 described above are performed. When it is determined that the amount of positional deviation is small, the process of measurement step 406 is executed, and when it is determined that the amount of positional deviation is large, the process of correction movement step 405 is executed.

In the measurement step 406, the measurement process is executed for the measurement points registered in advance (for example, the measurement points 15 and 16 in FIG. 2).
As described above, conventionally, the XY stage 11 and the Z stage 12 are moved in order to image a predetermined measurement position that has been set, and at other times, a correction movement is always performed to correct the amount of displacement. It was. For this reason, the correction movement is executed even when the correction of the positional deviation amount is unnecessary, so that it takes extra measurement time.
However, according to the present invention, it is possible to shorten the measurement time by arbitrarily setting the allowable misalignment value for each measurement image and omitting unnecessary misalignment correction movement.

  In the above-described embodiment, after the correction movement in the positional deviation correction moving step 405, the measurement image is acquired in the measurement image acquisition step 402, and then again the matching step 403, the pattern positional deviation determination step 404, and the positional deviation correction movement. When step 405 is executed, but the allowable displacement is large, the correction of the displacement is sufficient with only one correction movement. Depending on the measurement image or for all the measurement images, The correction of the misalignment amount may be omitted.

FIG. 5 is a diagram for explaining a method for automatically setting a misregistration allowable value according to the present invention. With reference to FIG. 5, a method for automatically setting the allowable displacement is described.
The setting of the positional deviation allowable value can be performed, for example, when creating or changing a product corresponding inspection program corresponding to the type of object to be measured (product, etc.).

In FIG. 5, a measurement image 50 is acquired. At this time, if the operator sets the matching area 14 and further sets the measurement location 15, the allowable displacement of this measurement image 50 is the distance 26 between the edge of the measurement image 50 and the measurement location 15 in the X direction. The y direction is the distance 23 between the edge of the measurement image 50 and the measurement location 15. This distance 26 is the right displacement tolerance, and the distance 23 is the upward displacement tolerance. In addition, the distance 26 'is the leftward displacement tolerance and the distance 23' is the downward displacement tolerance.
As described above, the image processing device 5 automatically sets the distances 23, 23 ′, 26, and 26 ′ from the top, bottom, left, and right ends of the measurement location 15 in the measurement image 50 to the measurement image end as misalignment tolerances. Setting is possible.

  Next, in FIG. 5, when the operator further sets the measurement location 16, the image processing unit 5 detects the leftward misalignment allowable value as the distance 25. Then, the image processing unit 5 compares the previous leftward allowable displacement value (distance 26 '), and registers the smaller one as the leftward allowable displacement value. Similarly, the distance 24 is registered for the downward displacement tolerance. The allowable values in the upward and right directions are detected in the same way, but in this case, since the value of the target location 15 previously registered is small, the setting remains unchanged.

Next, an embodiment of the present invention will be described with reference to FIG. 6 in which the image processing unit 5 changes the setting of the allowable misalignment value when the allowable misalignment value is incorrect. FIG. 6 is a diagram for explaining an embodiment of a method for correcting a positional deviation allowable value according to the present invention.
FIG. 6 shows that, in the measurement image 60, the operator is allowed to set the upper displacement allowance at distance 61, the lower displacement allowance at distance 62, the right displacement allowance at distance 63, and the left displacement allowance. This is an example when the value is set to 64. In FIG. 6, the actual pattern position deviation amount at the time of measurement is initially set at a distance of 65 (for the sake of simplicity, in the embodiment of FIG. 6, it is displaced only in the downward direction). Even if the allowable misalignment is less than 62, there will be a situation where measurement is not possible as in the case of the measured part 16.

In this way, the set misregistration allowable value is invalid if, for example, the misalignment allowable value temporarily set by the operator or the misalignment allowable value set for each product at one time, or the measurement target This occurs when only the target object has an abnormal displacement.
In this case, it is only necessary to calculate the amount of measurement (distance 66) and direction of the measurement area of the measurement location 16 where measurement is impossible, and to automatically correct the pattern position deviation allowable value 62 in the corresponding direction.
In other words, the new misregistration allowance value 62 'is obtained as "possible misregistration value 62' = actual pattern misregistration amount 65-measurement area protrusion 66".

  In the above-described embodiment, the object to be measured is moved to the measurement location and the correction movement is performed by the XY stage. However, the configuration is not limited to the XY stage, and may be configured to move the microscope side. Of course, a combination thereof may be used.

The block diagram which shows the structure of one Example of this invention. The figure for demonstrating an example of the measurement image of one Example of this invention. The figure for demonstrating an example of the measurement image of one Example of this invention. The flowchart of the measurement process of one Example of this invention. The figure for demonstrating one Example of the setting method of the position shift allowable value of this invention. The figure for demonstrating one Example of the method of correcting the position shift allowable value of this invention.

Explanation of symbols

1: Object to be measured, 1-0: Base, 2: Microscope, 2-1: Optical axis, 3: Objective lens, 4: Imaging unit, 5: Image processing unit, 6: Image processing monitor, 7: Illumination 7-1: Light guide 8: Device control unit 9: Device control monitor 10: Stage control unit 11: XY stage 12: Z stage 13: Pattern 14: Matching area 15, 16 : Measurement location, 20, 30, 50, 60: Measurement image, 21, 22: Center line, 23, 23 ', 24, 25, 26, 26', 61, 62, 63, 64, 65, 66: Distance .

Claims (4)

A microscope, an imaging unit that receives incident light from a measurement point of the measurement object through the microscope and outputs it as a video signal, an image processing unit that measures the size and position of the measurement point from the video signal, A moving means for moving at least one of the object to be measured or the imaging unit in order to move a measurement location of the object to be measured to a desired visual field position of the microscope, and the image processing unit includes: In the dimension measuring method of the dimension measuring apparatus for measuring the dimension and position of the subject portion by controlling the microscope, the imaging unit, and the moving unit based on inspection information set in advance,
Moving the location to be measured to the visual field position;
Detecting a shift amount between the moved visual field position and the position of the inspection information;
Determining whether the deviation amount is larger or smaller than a predetermined allowable value;
If the deviation amount is larger than the allowable value by the determination step, the step of correcting and moving the microscope visual field position according to the deviation amount,
A dimension measuring method of a dimension measuring apparatus, wherein the dimension or position of the subject portion is measured. A microscope, an imaging unit that receives incident light from a measurement point of the measurement object through the microscope and outputs it as a video signal, an image processing unit that measures the size and position of the measurement point from the video signal, A moving means for moving at least one of the object to be measured or the imaging unit in order to move a measurement location of the object to be measured to a desired visual field position of the microscope, and the image processing unit includes: In the dimension measuring method of the dimension measuring apparatus for measuring the dimension and position of the subject portion by controlling the microscope, the imaging unit, and the moving unit based on inspection information set in advance,
Moving the location to be measured to the visual field position;
Detecting a shift amount between the moved visual field position and the position of the inspection information;
Determining whether the deviation amount is larger or smaller than a predetermined allowable value;
The dimension measuring method of the dimension measuring apparatus, wherein if the deviation amount is smaller than the allowable value in the determining step, the dimension or position of the subject portion is measured. 3. The dimension measuring method of the dimension measuring apparatus according to claim 1, wherein when the inspection information is set, the tolerance value is automatically set at the time when the measurement location in the visual field position is set. A dimension measuring method for a dimension measuring apparatus, characterized by: A microscope, an imaging unit that receives incident light from a measurement point of the measurement object through the microscope and outputs it as a video signal, an image processing unit that measures the size and position of the measurement point from the video signal, A moving means for moving at least one of the object to be measured or the imaging unit in order to move a measurement location of the object to be measured to a desired visual field position of the microscope, and the image processing unit includes: In a dimension measuring apparatus for measuring the size and position of the subject portion by controlling the microscope, the imaging unit, and the moving unit based on inspection information set in advance,
Means for moving the location to be measured to the visual field position;
Means for detecting a shift amount between the moved visual field position and the position of the inspection information;
Means for determining whether the deviation amount is larger or smaller than a predetermined allowable value;
Means for correcting and moving the microscope visual field position according to the amount of deviation if the amount of deviation is greater than the allowable value by the determination step;
A dimension measuring apparatus for measuring a dimension or a position of the subject portion.

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