JP2003121383A - Method and device for inspecting periodic pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the pattern of a periodic pattern inspectable for areal deviation among the patterns by preparing an areal image which is equivalent to that prepared when no foreign matter adheres to an object to be inspected having the periodic pattern, even when foreign matter adhere to the object. SOLUTION: The image of the periodic pattern is inputted by photographing a shadow mask SM having the periodic pattern (step 11) and the areal image in which each pattern (hole) is arranged by converting the area of each pattern (hole) into a luminance value in the unit of picture elements (step 13), by measuring the area of each pattern (hole) and making the areas of holes zero when the holes are covered with dust even partially (step 12). Then the luminance values of picture elements having no luminance information due to their areas made to zero are interpolated with the luminance values of the surrounding picture elements (step 14), and visual inspections or automatic inspections are performed based on the obtained interpolated image (step 15).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inspecting a periodic pattern, in particular, a pattern such as a shadow mask used in a cathode ray tube of a color television, a substrate such as a color filter used in a liquid crystal display, and a pattern having a light transmitting property. Suitable for detecting deviations in the area of the pattern and unevenness thereof in a product that is formed in a
The present invention relates to a periodic pattern inspection method and apparatus.

[0002]

2. Description of the Related Art Industrial products having a periodic pattern in which a minute pattern as a unit is repeated include a shadow mask used in a cathode ray tube of a color television and a color filter used in a liquid crystal display.
In an industrial product having such a periodic pattern, each pattern has a predetermined shape and area (size) based on the design value, and with respect to the pattern existing around it, each pattern is They are repeatedly arranged with a predetermined space therebetween.

The area (size) of such individual patterns should be (1) always the same regardless of the location on the entire surface (entire) of the sample, or (2) gradually depending on the location in the sample. (For example, the area is increased from the center toward the periphery), and the like is formed according to a predetermined arrangement rule.

When manufacturing such an industrial product, it is necessary to perform the following inspections regarding the deviation (area deviation) of the area of each pattern from the design value. (1) If the deviation of the area exceeding the limit level occurs even in one pattern, it is regarded as a defect. (2) Even if the area deviation that can be regarded as normal within the limit level in the evaluation of each pattern is localized and concentrated in a plurality of patterns within a certain range, it is regarded as a defect. It should be noted that, in the latter case of detecting the local occurrence, even if the individual patterns are within the limit level, there is some variation in the area of each pattern. It means to inspect the non-uniformity (unevenness) of the area.

In order to inspect the displacement and non-uniformity of the areas between the respective patterns as described above, (1) a visual inspection in which an inspector directly inspects an inspection object (industrial product) directly with eyes, (2) )
Partial automatic inspection in which several representative areas are determined for the inspection object, the areas are image-input by an image pickup device, and the area of only the patterns included in the representative area is measured by image processing and inspected. ) Full surface of inspection object (whole)
There is a full-face automatic inspection in which an image is input and each area is measured and inspected for all patterns.

[0006]

However, in the visual inspection of (1) above, there are individual differences depending on the inspector, and it is easy to overlook, and in (2) partial automatic inspection, the inspection time is short. Although there is an advantage, the inspection is performed only in the representative region, so that the defect generated in the pattern in the other regions cannot be inspected. In addition, in (3) automatic inspection of the entire surface, the inspection time is very long because the entire surface is inspected, and in addition, the area is gradually changed depending on the place (area) in the sample. Since the area between each pattern and the limit level of the deviation are different for each area, it is necessary to inspect the measured area data by an inspector, but when the number of patterns increases, this inspection There is a problem that even if you try

Further, as a common problem in the automatic inspection, it is impossible to detect the unevenness defect in which the area deviations within the limit level are locally concentrated in each pattern.

The applicant of the present invention can easily inspect the deviation defect of the area generated in each pattern of the entire inspection object, and the unevenness of the area caused by the local concentration of the deviation within the allowable range. In order to make it possible to easily inspect even defects, Japanese Patent Application No. 2000-149332 discloses an invention of an inspection method for a periodic pattern, in which an inspection target having a periodic pattern is imaged and a pattern image is input.
The area of each pattern on the input pattern image is measured, the measured area of each pattern is converted into a brightness value, and each converted brightness value is set as a unit pixel with a fixed number of pixels as a unit. Then, unit pixels in which the respective brightness values are respectively set are arranged in association with the order of the respective patterns to create an area image, and the area deviation and its unevenness are inspected based on the created area image. Have already proposed.

Similarly, as an invention of an inspection apparatus for a periodic pattern, an image pickup means for taking an image of an inspection object having a periodic pattern and inputting a pattern image, and an area for each pattern on the input pattern image A means for measuring, a means for converting the measured area of each pattern to a luminance value, a means for setting each converted luminance value to a unit pixel in a unit of a fixed number of pixels, and each luminance value A unit for arranging each set unit pixel in association with the order of the respective patterns to create an area image, and a unit for inspecting an area deviation and its unevenness based on the created area image are provided. Have already proposed.

In the above proposed invention, an area image is created by converting the area of each pattern on the pattern image into a brightness value, and the deviation of the area is detected based on the change of the brightness value of the image. Therefore, it becomes possible to surely inspect the area deviation defect and the unevenness defect.

Hereinafter, the proposed invention will be described in detail based on specific examples with reference to the drawings.

FIG. 1 is a schematic perspective view including a block diagram showing a main part of an example of an inspection apparatus according to the proposed invention.

This inspection apparatus includes a stage 10 on which an inspection object W is placed, a CCD camera (imaging means) 12 arranged above the stage 10 for imaging the object W and inputting an inspection image. , An X-axis guide 1 for guiding the camera 12 in the X direction when the camera 12 is moved by a drive unit (not shown)
4, a Y-axis guide 16 that guides in the Y direction together with the guide 14, and the camera 12 that is guided by these guides 14 and 16 while scanning the camera W in the XY directions indicated by the arrows. The camera 1 when capturing the object W
The image processing unit 2 includes an image input unit 20 including a camera controller 18 that controls the image processing unit 2 and processes an inspection image captured by the CCD camera 12 and input.
2, the image processing unit 22 and the camera controller 18
And a device control unit 24 for controlling the entire device.

As shown in FIG. 2, the inspection apparatus is roughly classified into an inspection processing section 26, a human interface section 28, and a machine interface section 30.
In addition, the entire operation of each functional unit included in each of these units 26 to 30 is controlled by the device control unit 24. The inspection processing unit 26 includes the image input unit 20 as a functional unit and the image processing unit 22 that processes the image data input by the image input unit 20, and similarly, the human interface unit 28 includes the image processing unit 26. The information display unit 32 for displaying the result processed by the processing unit 22 and the interpersonal operation unit 34 for exchanging information with the operator are connected to the machine interface unit 30.
Is a machine interlocking part 36 for exchanging information with an external machine such as a belt conveyor (not shown) that conveys an object.
Each of the functional units 26 to 30 and the like is managed by the device control unit 24 as a whole.

Each of these functional units will be described in detail. The device control unit 24 that manages the operation of each of the functional units 26 to 30 described above.
As the device, a dedicated device, a general-purpose sequencer, a personal computer, or the like can be used. An area sensor camera or a line sensor camera can be used as the CCD camera 12 included in the image input section 20, and an image pickup tube or the like can be used as the image pickup means.

As the image processing unit 22, a dedicated image processing device, a personal computer or the like can be used. or,
The information display unit 32 informs the operator of the progress of the inspection,
It has the function of presenting inspection results, totaling results, history of past inspection results, etc., and displaying captured images, images in the middle of processing, and images after processing, such as CRT monitors, liquid crystal monitors, and LED arrays. Etc. are available.

Further, the interpersonal operation section 34 (1) accepts an input operation necessary for inspection from an operator, (2) sets characteristics (size, etc.) of an object to be inspected, and (3) image processing section 22. Set the adjustment value (filter size, etc.), (4)
It has a function of setting an adjustment value (shutter speed or the like) of the image input unit 20, and a mechanical button, a touch panel, a keyboard, a mouse or the like can be used for this.

Further, the machine interlocking unit 36 synchronizes with an external device at the time of automatic inspection, for example, the timing of ending the supply of the inspection object to the image input unit 20 or the like, and gives an instruction to the physical distribution apparatus to be inspected according to the inspection result ( Instructions for sorting and sorting inspection targets,
(Supply stop to inspection unit) etc. is issued, and RS-232C, RS-422, GPIB (General
Purpose Interface Bus), LAN (Ethernet), parallel I / O, relay, etc. can be used.

In this inspection apparatus, in the image processing section 22, the inspection object W having a periodic pattern is transferred to the C
Means for measuring (calculating) the area of each pattern on the pattern image captured by the CD camera 12 and input; means for converting the measured area of each pattern into a luminance value; A unit for setting each converted luminance value to a unit pixel having a fixed number of pixels as a unit and each unit pixel having each luminance value set are arranged in association with the arrangement order of each pattern. The means for creating the area image and the means for inspecting the area deviation based on the created area image are respectively constructed by software.

Next, the operation process when using the proposed inspection apparatus will be described with reference to the flowchart shown in FIG.

First, as shown in FIG. 1, the CCD camera 12 scans the inspection object W having a periodic pattern on the stage 10 to image the entire object W to form a pattern image. Input (step 1). When a shadow mask is used as the object W, the backside illumination (not shown) installed in the stage 10 is used to capture an aperture pattern as a transmitted light image.

Next, the area of each pattern on the input pattern image is measured (step 2). Here, the area is measured for each pattern. Specifically, the area can be measured by the following image processing.

That is, the input pattern image is binarized by using the threshold value experimentally obtained in advance for each sample, and the pixels forming each pattern are turned on in the binary image.
Convert to become the pixel of. In this manner, the ON pixels of the binarized image are subjected to the labeling process, the number of pixels forming each of the identically labeled individual patterns is obtained, and this is taken as the area.

After the area measurement is completed for each pattern of the pattern image in the above step 2, an area image is created (step 3). FIG. 4 shows an image of the relationship between the pattern image and the area image. It is assumed that (A) of the figure is a pattern image obtained by imaging the inspection object W, and (B) of the figure is a corresponding area image.

As shown in the enlarged view of the upper left corner portion of the pattern image of FIG. 4A, the area of each pattern is given by the numbers (1) to (7). If the value is a value, the brightness value of the area image corresponding to this value will be as shown in FIG. That is, one area obtained for each pattern in FIG. 4C is set as the brightness value of one pixel (unit pixel), and the area image is created by arranging the areas in the same order as the patterns in the pattern image. The brightness value in this case is 256
Not only the gradation, that is, 8 bits, but also 16 bits may be displayed according to the precision, or floating point may be used.

When the area image created in the above step 3 is displayed on the monitor of the information display section 32, not only defects of individual patterns but also stripes when the area deviation has a directionality are locally concentrated. When it does, it appears as unevenness, so that it can be visually confirmed on the monitor.

Here, in order to automatically inspect the area deviation, which will be described more specifically later, an emphasized image is created from the area image corresponding to FIG. 4D (step 4),
The emphasized image is binarized with a threshold value that is experimentally set in advance to create an area shift determination image (step 5).

A spatial filter corresponding to the shape of the defect (unevenness) to be detected is used for the emphasizing process in the above step 4. If the defect is a vertical stripe, the spatial filter as shown in FIG. 5A is used to process the luminance value of each pixel.
Each element forming this filter corresponds to each pixel, and the numeral is a coefficient by which the luminance value of each corresponding pixel is multiplied. Specifically, the brightness value of each pixel when the central element of this filter is matched with the target pixel is multiplied by each coefficient of the corresponding element, and the sum is used as the pixel value of the target pixel located at the center. The process of resetting is executed for the entire area image in units of A pixels in the vertical direction. The size A in the vertical direction and the number B of 0s in the horizontal direction are experimentally determined in advance in accordance with the defect to be detected and set appropriately.

FIG. 5B shows a spatial filter for emphasizing horizontal stripes. The spatial filter for emphasizing vertical stripes shown in FIG.
° It has a rotated configuration. Although not shown,
A spatial filter for highlighting spots is also used in order to extract spot-like unevenness that has no directionality in the area shift. this is,
It is necessary to prepare an appropriate structure according to the shape of the unevenness, but as an example, a structure in which the filters shown in FIGS. 5A and 5B are combined can be used.

As described above, by creating the area shift determination image in step 5, it is possible to perform the automatic inspection depending on whether or not the target binarized pixel exists in the determination image.

The proposed invention will be further described. Figure 6
4A is an example of a pattern image having a size of 4 vertical patterns and 10 horizontal patterns corresponding to FIG. The numbers shown at the top of this figure are the areas of the corresponding patterns indicated by →, and the area of each pattern (unit is, for example, [μm ² ]) is 2 from left to right,
It is formed with a design that increases from the top to the bottom by one, and although not shown in its entirety, it is assumed that it is formed between 10,000 and 10050.

For the defect-free pattern image of FIG. 6, the area between adjacent patterns is measured by image processing and arranged in order, as shown in FIG. 7 (A). A monochrome area image is created by converting the measured area in FIG. 7A into 8-bit luminance values. The figure (B) corresponds to this area image, and in this figure, the brightness values set in each pixel corresponding to each area are listed for convenience. The brightness value set for each pixel in FIG. 7B is calculated by a conversion formula of brightness = (area-10000) × 5.

The emphasis process of step 4 is performed on the area image of FIG. 7B. In this example, for the sake of convenience, in the example of the filter of FIG. 5A, the processing is performed by the filter having the configuration of [−1, 2, −1] corresponding to A = 1 and B = 0.
The case where the vertical stripe emphasized image shown in (C) is created is shown. In this figure (C), the positions of the cross marks at the left end and the right end represent an invalid region where the filtering process cannot be calculated. Note that the filter processing is applied to the area image of FIG. 7B here, but if it is not necessary to visually check it, or if it is desired to eliminate the error due to 8-bit conversion, the area of FIG. Filtering can be applied to the data itself.

When the vertical stripe-emphasized image is created as described above, the image is binarized by a predetermined threshold value as in step 5 to create the judgment image shown in FIG. . In this determination image, since there is no defect, the pixel value is only 0, which means that there is no defect.

On the other hand, FIG. 8 shows a pattern image when there is a deviation (defect) in the area, and in the case of FIG. 6 where there is no defect, the area is arranged in the order of 1008 → 10010 in the central pattern portion. Misalignment occurred, 10010 → 10
It has the same value like 010.

When the image data corresponding to FIGS. 7 (A) to 7 (D) is created for this defective pattern image, it becomes as shown in FIGS. 9 (A) to 9 (D), respectively. In this case, as shown in FIG. 6C, a vertical stripe-emphasized image in which the pixel values are emphasized in the positive and negative directions in the central portion of the pattern is created. As shown in (D), a pixel row having a pixel value of 1 meaning that there is a defect in the central portion of the pattern is extracted, and a vertical stripe-shaped area shift defect can be automatically detected.

Although a description based on a specific example is omitted, it is possible to automatically detect the case of the horizontal stripe-shaped area deviation and the case of the unevenness having a local spread.

As described in detail above, according to the proposed invention,
By creating an area image, which is a grayscale image representing the area data of each pattern over the entire surface of the sample (inspection object), and displaying it on a monitor, it is possible to visually inspect the area deviation.

When a spatial filter is applied to the created area image for automatic inspection of the area deviation, the stripe-shaped area deviation defect extending in the vertical and horizontal directions is
Since the deviation within the allowable level of the area can be regarded as the unevenness of the light and shade in the area image, it is possible to detect the deviation of the area image in the secondary order as already proposed by the applicant in Japanese Patent Laid-Open No. 6-229736. By applying the "algorithm for inspecting the unevenness of the opening area in the periodic pattern" using the differential spatial filter, it becomes possible to perform the automatic inspection of the locally generated area unevenness. Even when the area unevenness is automatically inspected as described above, the inspector can also verify the area data by visually inspecting the area image at the same time.

As described above, according to the proposed invention, the inspection object as a whole having a periodic pattern is
It is possible to easily inspect the deviation defect of the area of each pattern, and it is also possible to easily inspect the uneven defect of the area where the deviation within the allowable range locally occurs. .

However, as a result of further detailed study of the proposed invention detailed above, the present inventor has revealed the following new problems.

Now, the target sample (inspection object) W
However, if a shadow mask, a color filter, or the like whose overall image is shown in FIG. 10 (A), then such a sample W is manufactured as shown in a partially enlarged view in FIG. 10 (B). In the process, etc., foreign matter represented by dust in the figure may adhere. In addition, in this figure, it is assumed that the rectangles numbered 1 to 20 represent each pattern including the openings.

In order to inspect the sample W to which the foreign matter is attached in this manner, consider the case where a pattern image composed of a transmitted light image is picked up by illuminating from the back side of the sample W. In the transmitted light image obtained in this case, the area of each pattern consisting of a high-brightness portion is calculated by the above-mentioned method, the calculated area is converted into a luminance value, and the luminance value is converted into pixels corresponding to each pattern. An area image is created by setting each. Here, an area image corresponding to FIG. 4D obtained by imaging the portion of FIG. 10B (however,
If the image at the stage represented by the area S before conversion to the brightness value is FIG. 11A in which the number of each pattern is also shown in S, the range in which foreign matter is attached is shown. Then, the area of the pattern cannot be measured at all, or even if it is possible, a value greatly different from the normal area can be obtained. Therefore, the visual image of the area image obtained after converting the area corresponding to each pattern into the luminance value is as shown in FIG.
Pixels corresponding to 10, 11, 14, and 15 have extremely lower brightness than other patterns. In particular, since the pattern 11 has an area of 0, it is regarded as a non-opening portion that is not a pattern.

However, since the foreign matter attached to the sample W as described above can be removed in the cleaning step after the inspection, it is not necessary to detect it in the inspection based on the area image. Regardless, since it is regarded as a defect, normal visual inspection and automatic inspection cannot be performed.

The present invention has been made to solve the above-mentioned new problems, and an area image is created by converting the area of each pattern into luminance from an image of an inspection object having a periodic pattern. However, when inspecting a periodic pattern based on the area image, even if foreign matter is attached to the surface of the object, it is possible to create an area image equivalent to the case where no foreign matter is attached, and as a result, An object of the present invention is to provide a method and apparatus for inspecting a periodic pattern, which can inspect the characteristic pattern accurately and surely.

[0046]

According to the present invention, an object to be inspected having a periodic pattern is imaged, a pattern image is input, the area of each pattern on the input pattern image is measured, and each measured pattern is measured. Each area of the pattern is converted into a brightness value, each converted brightness value is set as a unit pixel in a unit of a fixed number of pixels, and the unit pixel in which each brightness value is set is set in the order of the patterns. A method for inspecting a periodic pattern in which an area image is created by arranging the areas in correspondence with each other and inspecting an area deviation and its unevenness based on the area image created, in which the area measured for each pattern is set in advance. It is determined whether or not there is a pattern below the set reference value. For the pattern whose area is determined to be below the reference value, the area of the adjacent pattern or the area is converted. By setting the area or luminance value obtained by interpolating using the degrees value is obtained by solving the above problems.

According to the present invention, an image pickup means for picking up an image of an inspection object having a periodic pattern and inputting a pattern image, and a means for measuring the area of each pattern on the input pattern image are measured. A unit for converting the area of each pattern into a brightness value, a unit for setting each converted brightness value as a unit pixel in a unit of a fixed number of pixels, and a unit pixel for which each brightness value is set, A periodic pattern inspection apparatus comprising: means for creating an area image by arranging the patterns in association with the order of the respective patterns; and means for inspecting an area deviation and unevenness thereof based on the created area image. In the area measured for each pattern, a means for comparing and determining whether or not a pattern having a preset reference value or less is present, and a pattern for which the area is determined to be the reference value or less is compared. Te is provided with the means for setting an area or luminance value obtained by interpolating using the luminance values converted from the area or the area of the adjacent patterns,
Similarly, the above problem is solved.

That is, in the present invention, when there is a pattern having an extremely small area compared to the normal area on the image of the object to be inspected, the area of the pattern and the brightness value of the adjacent pattern are compared. Since the area and the luminance value are used for the interpolation, the area image can be created substantially the same as the original area without the foreign matter attached, even if the foreign matter is attached.

[0049]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

In the periodic pattern inspection apparatus according to the present embodiment, in the image processing unit 22 shown in FIGS. 1 and 2, the area measured for each pattern further includes a pattern having a preset reference value or less. Means for comparing and determining whether the area is less than or equal to a reference value, and means for setting a luminance value interpolated using the luminance value converted from the area of the adjacent pattern It is substantially the same as the proposed inspection apparatus shown in the figure, except that and are realized by software. Therefore, detailed description thereof will be omitted.

In the present embodiment, according to the flow chart shown in FIG. 12, an image of the object to be inspected to which the foreign matter is attached as shown in FIG. 10 is picked up to create an area image substantially the same as the case where no foreign matter is attached. To do.

That is, a sample (inspection object) W composed of the shadow mask shown in FIGS. 13A and 13B, which is the same as FIGS. 10A and 10B, is used in the same manner as in the proposed invention. An image pickup device such as an area sensor or a line sensor camera is used to image the shadow mask (SM) with transmitted light, and the transmitted light image is input as a pattern image (step 11).

With respect to the obtained pattern image (not shown), the area of each hole (opening) was measured,
Area array data in units of pixels shown in FIG. 13C corresponding to FIG. 13A is created (step 12). Here, the area is binarized with a threshold value experimentally obtained in advance for the sample W, the binarized image is labeled, and the number of pixels forming each pattern is counted to obtain the area. At that time, as shown in the drawing, not only the pattern that is not labeled because it is completely covered with dust but also a part is covered and the area of the pattern that is equal to or less than the threshold value (reference value) for determination is also zero. The threshold value set here is experimentally obtained in advance.

Then, each area of the array obtained as shown in FIG. 13C is converted into a brightness value, and pixels having the area as a brightness value are arranged in accordance with the array of the pattern. A first area image shown in D) is created (step 13). Then, in the first area image, the brightness value of the pixel having no brightness information because it is covered with dust is set by interpolation using the brightness values of the neighboring pixels (step 14).

This interpolation processing is performed by the first processing shown in FIG. 13 (D).
When a pixel having a luminance value of 0 is found by scanning the area image from the upper left, this is designated as pixel A as shown in FIG. The pixel above the pixel A is referred to as the pixel B, and the pixel to the left of the pixel A is referred to as the pixel C. These two adjacent pixels always exist.

Next, the pixel A is scanned downward, the pixel whose luminance value is not 0 is found, and it is set as the pixel D. Similarly, the pixel A is scanned to the right and the pixel whose pixel value is not 0 is found. And This state is shown in FIG.

As described above, with respect to the pixel A, in addition to the upper and left adjacent pixels B and C, the pixels D and E located in the lower and right directions, respectively.
When is determined, the brightness is calculated according to the rule shown by the following formula, and the calculated brightness is set to the pixel A as A ′ as shown in FIG.

<When Pixels D and E are Adjacent> Brightness Value of Pixel A = (Brightness Value of Pixel B + Brightness Value of Pixel C +
Pixel D brightness value + Pixel E brightness value) / 4

<When Pixels D are not Adjacent> Pixel A Luminance Value = (Pixel B Luminance Value + Pixel C Luminance Value +
Luminance value of pixel E) / 3

<Pixel E is not adjacent> Luminance value of pixel A = (luminance value of pixel B + luminance value of pixel C +
Luminance value of pixel D) / 3

<When Pixels D and E are not Adjacent> Brightness Value of Pixel A = (Brightness Value of Pixel B + Brightness of Pixel C) ÷
Two

Similar processing is repeated from the pixel A as a starting point until there are no pixels having a luminance value of 0, and an interpolated image shown in FIG. 6F is created as a final area image. afterwards,
Visual inspection or automatic inspection is performed based on the area image obtained by performing the interpolation process in this manner.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the above-described embodiment, the case where the area is compared with the reference value and the luminance value is interpolated has been described, but the interpolation processing may be performed at the area stage. Also, the comparison with the reference value may be performed after conversion into the luminance value.

Also, the interpolation method is not limited to that shown in the above embodiment, and for example, the nearest neighbor interpolation method of substituting the brightness value of the pixel B or the pixel C closest to the pixel A may be adopted. This method has the advantage that the algorithm is simple and the processing is fast.

The method of measuring the area of the pattern is not limited to the above example, and a known image processing algorithm for measuring the area of a gray image with high accuracy may be used.
A commercially available device that can actually measure the area from a gray image with sub-pixel accuracy may be used.

Further, in the above embodiment, the case where the unit pixel forming the area image is one pixel has been described, but it is not particularly limited as long as a fixed number is used as a unit, and one area is used as a unit of a plurality of pixels. You may make it convert.

[0068]

As described above, according to the present invention, an area image is created by converting the area of each pattern into luminance from an image of an inspection object having a periodic pattern, and based on the area image. When inspecting the periodic pattern, even if foreign matter is attached to the surface of the object, it is possible to create an area image equivalent to the case where there is no foreign matter attached, and as a result, the periodic pattern can be accurately and reliably obtained. Can be inspected.

[Brief description of drawings]

FIG. 1 is a schematic perspective view including a block diagram, showing a main part of an example of an inspection apparatus according to a proposed invention.

FIG. 2 is a block diagram showing an outline of the entire inspection device.

FIG. 3 is a flowchart showing the operation of the proposed invention.

FIG. 4 is an explanatory diagram showing an image of a relationship between a pattern image and an area image.

FIG. 5 is an explanatory diagram showing an example of each spatial filter for vertical stripe enhancement and horizontal stripe enhancement.

FIG. 6 is an explanatory diagram showing an example of an image of a pattern image when there is no defect.

FIG. 7 is an explanatory view showing each processed image obtained based on the pattern image of FIG.

FIG. 8 is an explanatory diagram showing an example of an image of a pattern image when there is a defect.

9 is an explanatory view showing each processed image obtained based on the pattern image of FIG.

FIG. 10 is an explanatory diagram showing characteristics of an inspection object.

FIG. 11 is an explanatory diagram showing characteristics of an area image obtained from the inspection object.

FIG. 12 is a flowchart showing the operation of one embodiment.

FIG. 13 is an explanatory diagram showing the characteristics of the former stage of the inspection process according to the present embodiment.

FIG. 14 is an explanatory view showing the features of the latter stage of the inspection process according to the present embodiment.

[Explanation of symbols] 10 ... Stage 12 ... CCD camera 14 ... X-axis guide 16 ... Y-axis guide 18 ... Camera controller 20 ... Image input section 22 ... Image processing unit 24 ... Device control unit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F065 AA49 AA58 BB02 CC25 FF02                       HH13 HH15 JJ02 JJ03 JJ09                       JJ25 JJ26 MM24 PP03 PP12                       QQ00 QQ03 QQ05 QQ21 QQ24                       QQ25 QQ27 QQ32 RR05                 2G051 AA90 AB20 CA04 DA05 EA11                       EB01 EC05 ED07                 2H088 FA13 HA12

Claims (6)

[Claims] 1. An object to be inspected having a periodic pattern is imaged, a pattern image is input, the area of each pattern on the input pattern image is measured, and the area of each measured pattern is set as a brightness value. After conversion, each converted luminance value is set as a unit pixel with a fixed number of pixels as a unit, and the unit pixels having each luminance value set are arranged in association with the order of each pattern and the area is set. A method of inspecting a periodic pattern for creating an image and inspecting an area shift and its unevenness based on the created area image, in which the area measured for each pattern has a pattern equal to or less than a preset reference value. It is judged whether or not it exists, and for the pattern whose area is judged to be less than the reference value, it is interpolated using the area of the adjacent pattern or the brightness value converted from the area. A method for inspecting a periodic pattern, characterized in that the obtained area or brightness value is set. 2. The method for inspecting a periodic pattern according to claim 1, wherein the comparison / determination process of the area and the reference value is performed using the luminance value converted from the area instead of the area. . 3. The area of each pattern is measured by binarizing an input pattern image with a predetermined threshold value and based on the number of pixels corresponding to each binarized pattern. The method for inspecting a periodic pattern according to claim 1. 4. The periodic pattern inspection method according to claim 1, wherein the area image is enhanced by a spatial filter to create an enhanced image, and the enhanced image is inspected. 5. An image pickup means for picking up an image of an inspection object having a periodic pattern and inputting a pattern image, a means for measuring an area of each pattern on the input pattern image, and an area of each measured pattern. To a brightness value, a means for setting each converted brightness value to a unit pixel having a fixed number of pixels as a unit, and a unit pixel to which each brightness value is set, respectively. An inspection device for a periodic pattern, comprising: means for creating an area image by arranging the areas in association with each other; and means for inspecting an area deviation and its unevenness based on the created area image. A means for comparing and determining whether or not a pattern having a preset reference value or less exists in the measured area, and a means for comparing the pattern for which the area is determined to be the reference value or less are provided next to each other. An apparatus for inspecting a periodic pattern, comprising: an area of a contact pattern or a means for setting an area or a brightness value interpolated using a brightness value converted from the area. 6. The periodic pattern inspection apparatus according to claim 5, wherein the comparison / determination process of the area and the reference value is performed using the luminance value converted from the area instead of the area. .