JP2010117185A - Device and method for inspecting flaw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flaw inspecting device capable of detecting the pattern shift of an inspection substrate only on the basis of a part of excellent article pattern data, dispensing with even the estimate position data of the whole surface of an inspection region and capable of suppressing data to a necessary minimum amount, and a flaw inspecting method. <P>SOLUTION: The flaw inspecting device is equipped with a means for imaging a substrate to be inspected, a means for capturing the taken substrate image, a means for storing the captured substrate image as an inspection image, a means for taking out a part of the stored inspection image to set the same as a reference image for pattern matching and setting an inspection condition, a means for storing the set reference image and the set inspection condition, a means for performing pattern matching using the stored inspection image and reference image, a means for calculating the shift quantity of the inspection image and the reference image as a result of pattern matching, and a means for displaying the data showing the calculated shift quantity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a defect inspection apparatus and a defect inspection method for detecting defects in patterns such as electric signal wirings and transistor electrodes formed on a large substrate used for a large liquid crystal panel or the like.

  Conventionally, in a photolithography process, which is a manufacturing process of a TFT liquid crystal substrate, a defect may occur in a pattern formed on the substrate due to an abnormality in a manufacturing apparatus or an exposure apparatus. For example, when particles adhere to the substrate, a local pattern shift occurs, and the portion is manifested as unevenness.

  Further, in the case of an abnormality in an exposure apparatus, particularly in the case of a lens scanning system that is a recent exposure means, a pattern shift between lenses occurs due to an abnormality in lens adjustment, which appears as streaky irregularities. Although these irregularities occur even with a minute pattern shift, they do not become abnormal electrically, and are difficult to detect in a later process. For this reason, unevenness is detected by a macro inspection or the like that a human observes with the naked eye.

As a method of automatically quantifying the macro inspection, the predicted position information predicted to appear the feature point of the repetitive pattern is obtained in advance using a non-defective substrate with an accuracy smaller than the image resolution, and the predicted position and There is a technique for detecting a pattern shift by obtaining an error from a measurement position. (For example, refer to Patent Document 1).
JP 2004-279244 A

  However, in the conventional technique, it is necessary to generate predicted position information using an actual substrate in advance, and the substrate must be a good product. However, since it takes time to manufacture a non-defective substrate at the start of the manufacturing process, there has been a problem that the conventional technique cannot perform the corresponding inspection until then.

In addition, since it is necessary to have the predicted position information of all inspection areas on the substrate in all processes and all types of substrates to be inspected, there is a problem that the amount of information becomes enormous.
Further, when comparing the predicted position and the measurement position, there is a problem that strict alignment is required and the processing becomes complicated.

  The present invention has been made in view of the problems as described above, and it is possible to detect the pattern deviation of the inspection substrate only with some non-defective pattern information, and the predicted position information on the entire inspection area is not necessary, It is an object of the present invention to provide a defect inspection apparatus and a defect inspection method capable of suppressing the necessary minimum amount of information.

The present invention employs the following configuration in order to solve the above problems.
That is, according to one aspect of the present invention, the defect inspection apparatus according to the present invention includes an imaging unit that images a substrate to be inspected, an image capturing unit that captures a substrate image captured by the imaging unit, and the image capturing unit. Image storage means for storing the substrate image captured by the above as an inspection image, and a reference image setting for extracting a part of the inspection image stored in the image storage means, setting it as a reference image for pattern matching, and setting inspection conditions Means, reference image storage means for storing the reference image and setting conditions set by the reference image setting means, inspection images stored in the image storage means, and reference images stored in the reference image storage means Pattern detection means for performing pattern matching using the pattern detection result by the pattern detection means, the inspection image and the reference Characterized in that it comprises a pattern shift amount calculating means for calculating a shift amount between the image and a shift amount display means for displaying the information indicating the shift amount calculated by the pattern shift amount calculation means.

  In the defect inspection apparatus according to the present invention, the deviation amount display means may calculate a deviation distance and a deviation direction of the pattern between the inspection image and the reference image based on the deviation amount calculated by the pattern deviation amount calculation means. It is desirable to calculate and visually display the shift distance and the shift direction.

In the defect inspection apparatus of the present invention, it is desirable that the deviation amount display means adds a color to the code indicating the deviation distance and the deviation direction or blinks the code.
The defect inspection apparatus of the present invention preferably further comprises a determination unit that determines the type of unevenness that appears on the substrate to be inspected based on the distribution of the shift amount calculated by the pattern shift amount calculation unit. .

  Moreover, according to one aspect of the present invention, the defect inspection method of the present invention is a defect inspection method for inspecting a defect of a substrate to be inspected, which images the substrate to be inspected and captures the captured substrate image. An inspection image is stored in a memory, a part of the inspection image stored in the memory is taken out, set as a reference image for pattern matching, an inspection condition is set, and the set reference image and setting condition are stored in the memory. The pattern matching is performed using the inspection image and the reference image stored in the memory, and the amount of deviation between the inspection image and the reference image is calculated as a result of the pattern matching, and the calculated deviation Information indicating the quantity is displayed on a display device.

According to the present invention, it is not necessary to prepare information in advance using a non-defective substrate, and it is possible to detect a pattern shift by simple means.
In addition, according to the present invention, it is possible to determine the unevenness that is manifested, so that it is possible to detect an abnormality in the manufacturing process at an early stage.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a first embodiment to which the present invention is applied will be described.
FIG. 1 is a functional block diagram of a defect inspection apparatus according to a first embodiment to which the present invention is applied.

  In FIG. 1, a defect inspection apparatus 10 includes a camera unit 2 as an imaging unit, an image capture unit 3, an image storage unit 4, a reference image setting unit 5, a reference image storage unit 6, a pattern detection unit 7, and a pattern deviation amount calculation. A unit 8 and a shift amount display unit 9 are provided.

  The camera unit 2 can capture a predetermined area on the inspection substrate 1 placed on a movable stage as a one-dimensional image or a two-dimensional image. The image capturing unit 3 captures a substrate image captured by the camera unit 2. The image storage unit 4 can store the substrate image captured by the image capturing unit 3 as a two-dimensional inspection image.

The reference image setting unit 5 takes out a part of the inspection image stored in the image storage unit 4,
A reference image for pattern matching is set, and an inspection condition is set. The reference image unit 6 stores the reference image and setting conditions set by the reference image setting unit 5. The pattern detection unit 7 performs pattern matching using the inspection image captured at the time of inspection of the substrate 1 to be inspected and stored in the image storage unit 4 and the reference image stored in the reference image unit 6. A position where the image matches the reference image is detected. The pattern deviation amount calculation unit 8 calculates a pattern deviation distance and a deviation direction based on the difference between the inspection image and the reference image as a result of pattern matching by the pattern detection unit 7.

  The deviation amount display unit 9 visually indicates the deviation distance and the deviation direction, for example, the deviation distance and the deviation direction as a result of showing the deviation of the pattern calculated by the pattern deviation amount calculation unit 8. The code is displayed with a color or blinking the code.

  As described above, the reference image setting unit 5 extracts a part of the inspection image stored in the image storage unit 4 and sets a reference image for pattern matching. Next, a specific example will be described. To do.

FIG. 2 is a diagram for explaining the setting of the reference image.
As shown in FIG. 2, the reference image setting unit 5 takes out an image of a part of the inspection image stored in the image storage unit 4 and having no pattern deviation for one pixel of the liquid crystal. Then, this is used as a reference image 100, and a model 101 used for pattern matching is set. Note that the entire one pixel of the liquid crystal display device may be set as the pattern matching model 101.

  Further, the reference image setting unit 5 sets an area for detecting a positional shift. In the example illustrated in FIG. 2, the area 102 and the area 103 are set as areas for detecting misalignment. The reference image setting unit 5 sets a region of the liquid crystal panel to be inspected in the substrate 1 to be inspected. As described above, these pieces of information are stored in the reference image storage unit 6.

Next, the flow of inspection processing for inspecting the substrate 1 to be inspected will be described.
FIG. 3 is a flowchart showing a flow of inspection processing for inspecting a substrate to be inspected, FIG. 4 is a diagram for explaining pattern matching between an inspection object and a model, and FIG. FIG. 6 is a diagram illustrating an example, and FIG. 6 is a diagram for explaining a shift distance.

First, in step S31 of FIG. 3, the camera unit 2 images the substrate 1 to be inspected. A description of the mechanical operation of the defect inspection apparatus 10 is omitted.
Next, in step S <b> 32, the board image captured in step S <b> 31 is stored in the image storage unit 4 via the image capturing unit 3.

  Next, in step S33, the pattern detection unit 7 sequentially reads out the image of the inspection target area from the substrate image stored in the image storage unit 4 in step S32 by a predetermined area. In step S 34, the pattern detection unit executes pattern matching using the pattern matching model 101 stored in the reference image storage unit 6. Specifically, as shown in FIG. 4, all corresponding patterns in the substrate image are detected, and a detection position M (X (ij), Y (ij)) that matches the model 101 is obtained with subpixel accuracy.

Next, in step S35 of FIG. 3, the inspection image 110 having the same size as the reference image 100 is cut out from the detection position M obtained in step S34, and the difference from the reference image 100 is calculated. Here, in the difference processing between the inspection image 110 and the reference image 100, first, an image filter such as averaging is applied to the inspection image 110 and the reference image 100. Then, as shown in Conditional Expression 1 below, pixels whose difference value dP (ij) corresponding to each of the two images is equal to or less than a preset contrast threshold Cs are uniformly set to a pixel value = 128 as a background image. When the difference value is larger than the contrast threshold Cs and becomes a negative value, the pixel value = 0 is uniformly set, and when the difference value is a positive value, the pixel value = 255 is set.
When dP (ij) ≦ Cs dP (ij) = 128
When dP (ij)> Cs dP (ij) = 255
When dP (ij)> Cs∩dP (ij) <0 dP (ij) = 0
... Condition 1
As a result, as shown in FIG. 5, the difference image 120 in which only the pattern misalignment is emphasized is obtained.

Next, when the misalignment detection areas 102 and 103 are applied and, as shown in FIG. 6, for example, the misalignment in the X direction is detected in the area 102, misalignment occurs on both sides of the pattern. An average value of the number of pixels Dx (ij) having a pixel value of 0 and the number of pixels Bx (ij) having a pixel value of 255 is defined as a deviation distance Px (ij) in the X direction (conditional expression 2). Further, when detecting a deviation in the Y direction in the area 103, an average value of the number of pixels Dy (ij) having a pixel value of 0 in the Y direction and the number of pixels By (ij) having a pixel value of 255 is calculated as a deviation distance in the Y direction. Let Py (ij) (conditional expression 2).
Px (ij) = (Dx (ij) + Bx (ij)) / 2
Py (ij) = (Dy (ij) + By (ij)) / 2
... Condition 2
Further, in the difference image 120, the pattern is shifted in the direction from the pixel value 255 to the pixel value 0, and the shift direction can also be calculated. If a sign is set for the shift direction, the shift distance R Digitization is possible by multiplying (Px (ij), Py (ij)) by a sign.

  Then, in step S36 in FIG. 3, the detected position M (X (ij), Y (ij)) obtained in steps S34 and S35 and the shift distance (Px (ij), Py (ij)) are displayed as a deviation amount. The result is displayed on the monitor of the section 9, and the situation is notified to the operator. If the vector arrows are used to indicate the shift distance and shift direction as a result display, the situation can be easily grasped.

Next, a second embodiment to which the present invention is applied will be described.
In the second embodiment, the process of determining which type of unevenness the detected deviation is based on the relationship between the detected position M of the detected deviation and the deviation distance R is the first embodiment. It is added. Note that the process up to the calculation of the detection position M and the deviation distance R is the same as that in the first embodiment, and thus the description thereof is omitted.

  FIG. 7 is a view showing an example of unevenness caused by particles adhering to the substrate, FIG. 8 is a view showing an example of unevenness caused by a displacement between scanning lenses of the exposure apparatus, and FIG. 9 is an exposure view. It is a figure which shows the example of the position shift of the board | substrate fixing mechanism of an apparatus.

  After calculating the detection position M and the shift distance R described in the first embodiment, the absolute values of the calculated shift distances R (Px (ij), Py (ij)) are preset standard values. A detection position MM (X (ij), Y (ij)) that is greater than or equal to ST is obtained. Then, the degree of dispersion of the detection position MM is obtained, and the corresponding unevenness type is obtained.

For example, as shown in FIG. 7, when the deviation distance and the deviation direction are displayed as vectors, if the vector is rounded within a certain range, it is determined that the unevenness is caused by particles adhering to the substrate 1 to be inspected. In addition, as shown in FIG. 8, when the vector looks like a continuous streak in a certain direction, it is determined that the unevenness is caused by the deviation between the scanning lenses of the exposure apparatus.
Also, as shown in FIG. 9, when the substrate image is uniformly distributed over the entire substrate and the displacement direction is constant, it is determined that the substrate fixing mechanism of the exposure apparatus is displaced.

  In this way, when displaying the deviation distance and deviation direction as a result display, it is possible to detect abnormalities of the inspected substrate 1 at an early stage by determining what kind of unevenness is manifested by the detected deviation characteristics. It leads to.

  The present invention is not limited to the above-described embodiments and the like, and can take various configurations or shapes without departing from the gist of the present invention.

It is a functional block diagram of the defect inspection apparatus in 1st Embodiment to which this invention is applied. It is a figure for demonstrating the setting of a reference image. It is a flowchart which shows the flow of the inspection process for test | inspecting a to-be-inspected board | substrate. It is a figure for demonstrating the pattern matching with a test object and a model. It is a figure which shows the example of a difference image. It is a figure for demonstrating deviation | shift distance. It is a figure which shows the example of the nonuniformity resulting from the particle adhering to a board | substrate. It is a figure which shows the example of the nonuniformity resulting from the shift | offset | difference between the scanning lenses of exposure apparatus. It is a figure which shows the example of the position shift of the board | substrate fixing mechanism of exposure apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board to be inspected 2 Camera part 3 Image capture part 4 Image memory | storage part 5 Reference image setting part 6 Reference image memory | storage part 7 Pattern detection part 8 Pattern deviation | shift amount calculation part 9 Deviation amount display part 10 Defect inspection apparatus 100 Reference image 101 Model 102 area 103 area 110 inspection image 120 difference image

Claims (5)

Imaging means for imaging a substrate to be inspected;
Image capturing means for capturing a substrate image captured by the image capturing means;
Image storage means for storing the substrate image captured by the image capture means as an inspection image;
A part of the inspection image stored in the image storage means is taken out, set as a reference image for pattern matching, and a reference image setting means for setting inspection conditions;
Reference image storage means for storing a reference image and setting conditions set by the reference image setting means;
Pattern detection means for performing pattern matching using the inspection image stored in the image storage means and the reference image stored in the reference image storage means;
As a result of pattern matching by the pattern detection means, a pattern deviation amount calculation means for calculating a deviation amount between the inspection image and the reference image;
A deviation amount display means for displaying information indicating the deviation amount calculated by the pattern deviation amount calculation means;
A defect inspection apparatus comprising:   The deviation amount display means calculates a deviation distance and a deviation direction of the pattern between the inspection image and the reference image based on the deviation amount calculated by the pattern deviation amount calculation means, and the deviation distance and the deviation direction. The defect inspection apparatus according to claim 1, wherein the defect is visually displayed.   The defect inspection apparatus according to claim 2, wherein the shift amount display unit colors or blinks the code indicating the shift distance and the shift direction. further,
Judgment means for judging the type of unevenness that appears on the substrate to be inspected based on the distribution of deviation amounts calculated by the pattern deviation amount calculation means;
The defect inspection apparatus according to any one of claims 1 to 3, further comprising: A defect inspection method for inspecting a defect of a substrate to be inspected,
Image the substrate to be inspected,
The captured substrate image is captured and stored in a memory as an inspection image,
Taking out a part of the inspection image stored in the memory, setting it as a reference image for pattern matching, setting the inspection conditions,
Storing the set reference image and setting conditions in a memory;
Perform pattern matching using the inspection image and the reference image stored in the memory,
As a result of the pattern matching, a shift amount between the inspection image and the reference image is calculated,
Displaying information indicating the calculated deviation amount on a display device;
A defect inspection method characterized by that.

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