WO2000052644A1 - Procede et dispositif d'inspection d'un schema - Google Patents

Procede et dispositif d'inspection d'un schema Download PDF

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Publication number
WO2000052644A1
WO2000052644A1 PCT/JP1999/006138 JP9906138W WO0052644A1 WO 2000052644 A1 WO2000052644 A1 WO 2000052644A1 JP 9906138 W JP9906138 W JP 9906138W WO 0052644 A1 WO0052644 A1 WO 0052644A1
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WIPO (PCT)
Prior art keywords
defect
image
pattern
substrate
defects
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PCT/JP1999/006138
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English (en)
Japanese (ja)
Inventor
Hilario Haruomi Kobayashi
Hiroya Koshishiba
Mitsunobu Isobe
Kazushi Yoshimura
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Hitachi, Ltd.
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Publication of WO2000052644A1 publication Critical patent/WO2000052644A1/fr

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/0002—Inspection of images, e.g. flaw detection
    • G06T7/0004—Industrial image inspection
    • G06T7/0006—Industrial image inspection using a design-rule based approach
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30108—Industrial image inspection
    • G06T2207/30141—Printed circuit board [PCB]

Definitions

  • the present invention relates to a pattern inspection method and a device for detecting a wiring pattern with high accuracy in an automatic appearance inspection apparatus for a printed wiring board, a ceramic substrate, a green sheet, and the like.
  • a simple binarization that is, a binarization process using a single binarization threshold is generally used as a pattern detection method.
  • a fixed threshold value is used in order to stably detect a thin hairline-shaped disconnection defect occurring in a wiring pattern.
  • a method is used in which a binary image obtained by the above and a binarized image of the second derivative are combined. According to this method, a wiring pattern to be detected is detected at a fixed threshold value, and a hairline-shaped disconnection defect or a short defect that shorts between wiring patterns is detected by a second-order differential image. It is configured so that
  • a thin hairline-shaped defect portion becomes a steep signal change by second-order differentiation of a grayscale image of a detected wiring pattern. This will detect such defects.
  • pinhole defects pinhole-shaped defects that occur inside the conductor pattern
  • the signal change in a grayscale image is gradual, so that the effect of the appearance of such a defect by the second derivative processing is small. Since the trust is low, it cannot be detected with the binarization threshold set in the normal case.
  • defects that occur in the wiring pattern include under-determined defects (also referred to as missing defects, such as pinholes, breaks and half-breaks) and surplus defects (or protruding defects). These are the defects such as scattering, isolated points, semi-short and short, etc.), but it is difficult to treat these defect modes equally with a single binarization threshold It is. Disclosure of the invention
  • An object of the present invention is to solve such a problem and to stably extract a detection target from an image without depending on differences in graphic properties or changes in target pattern density due to the shape or area of the detection target. It is an object of the present invention to provide a pattern inspection method and an apparatus therefor.
  • an image of the substrate is obtained by capturing an image of the substrate, and the image is displayed for each type of defect set in advance. Then, processing is performed based on different conditions to detect defects for each type of defect, and an image of the detected defect for each type of defect is displayed on the screen.
  • the preset different condition for each defect type is a threshold value for binarizing an image or a second derivative image of the image.
  • the types of defects to be detected are pinholes, disconnections, semi-disconnections, Include at least one type of standing, short or semi-short.
  • the image of the defect displayed on the screen is an image of a specified defect among the detected defects, and is displayed at a specified magnification.
  • image processing conditions are inputted and stored, and an image of the substrate is obtained by imaging the substrate.
  • the image is processed based on the stored image processing conditions to detect a defect with a minimum defect detection size that differs for each type of defect, and an image of the detected defect is displayed on a screen.
  • the image processing conditions are made different depending on the types of pattern defects.
  • the types of defects to be detected include at least one of pinholes, broken wires, partially broken wires, flying, isolated points, short or half shorts.
  • an image of the detected defect is displayed on the screen together with information relating to the image processing conditions.
  • an image of the substrate is obtained by imaging the substrate, and this image is set in a first preset manner. Processing is performed based on the image processing conditions to detect a surplus defect, and the image is processed based on a second image processing condition set in advance to detect a defect of the insufficient system. At least one of the image of the defect and the image of the defect of the insufficient system is displayed on the screen.
  • the surplus defects to be detected include at least one of scattering, isolated points, short or short shots, and the shortage defects include pinholes and cuts. Include at least one of the lines and half-broken lines.
  • an image of the detected defect is displayed on a screen together with information related to the first or second image processing condition.
  • an image of the substrate is obtained by capturing an image of the substrate, and the image is processed for each type of defect. Defects are detected with different minimum defect detection sizes, a specific type of defect image is selected from the detected defect images and displayed on the screen, and a local area in the defect image displayed on this screen is displayed. The image is displayed on a larger scale than the displayed image of the defect.
  • the present invention provides an apparatus for inspecting a pattern formed on a substrate for defects, an imaging unit for imaging the substrate to obtain an image of the substrate, Storage means for storing different image processing conditions in the storage means, and a defect detection method for detecting a defect by processing an image obtained by the imaging means based on different image processing conditions for each type of defect stored in the storage means.
  • the image processing condition that differs for each type of defect stored in the storage means is a threshold value for binarizing the image or a second derivative image of the image.
  • the defect detected by the defect detection means includes at least one of pinhole, disconnection, semi-disconnection, scattering, isolated point, short or half short.
  • the display means displays the local area of the image of the defect displayed on the screen in a larger scale than the displayed image of the defect.
  • the present invention provides a method for forming a butterfly formed on a substrate.
  • the defects detected by the defect detection means include at least one of pinholes, broken wires, partially broken wires, flying, isolated points, short shots and half shots.
  • the display means displays the image of the defect on the screen together with information relating to the image processing conditions of the image of the defect.
  • FIG. 1 is a diagram showing an embodiment of a pattern binarization method according to the present invention.
  • FIG. 2 is a diagram showing a specific example of a second derivative operator for obtaining a second derivative image in FIG.
  • FIG. 3 is a diagram showing a specific example of an area division operator for area division in FIG.
  • FIG. 4 is a diagram showing types of defects to be inspected on a wiring pattern.
  • FIG. 5 is a diagram showing a pattern connection relation extraction process for detecting a defect.
  • FIG. 6 is a diagram showing the entire configuration of an inspection algorithm using the pattern binarization method according to the present invention.
  • FIG. 7 is a diagram showing the relationship between the minimum width of the pattern and the size of the area dividing operator.
  • FIG. 8 is a diagram showing the relationship between the pattern edge width and the size of the area dividing operator.
  • FIG. 9 is a diagram showing criteria for setting each binarization threshold shown in FIG.
  • FIG. 10 is a diagram showing the relationship between the set threshold value and the detection sizes of pinhole defects and scattering defects.
  • FIG. 11 is a diagram showing a specific example of a display screen in the image display means shown in FIG. BEST MODE FOR CARRYING OUT THE INVENTION
  • the wiring pattern formed on the printed circuit board, ceramic substrate, and green sheet (hereinafter, represented by the printed circuit board) includes the disconnection and wiring of the wiring pattern 1.
  • the width of pattern 1 is the reference value (design specification
  • Insufficient defects also called missing defects or concave defects
  • defects such as narrower half-open lines and pinholes
  • surplus defects represented by defects such as half-shorts, shorts, and scattering.
  • System defects also called protruding defects or convex defects
  • a wiring pattern inspection device such as a visual inspection device inspects the presence or absence of such a defect.
  • FIG. 5 is a diagram showing a pattern connection relation comparison method which is an example of such a defect inspection algorithm in the wiring pattern inspection apparatus. The details of such an inspection algorithm are described in Patent No. 1,589,933, and the principle thereof will be briefly described here.
  • connection relation comparison method binarizes the grayscale image of the detected wiring pattern and expands the binary pattern into a thick line to form a half short part (pattern interval is less than the reference value).
  • the image pattern obtained by the dilation system and the image pattern obtained by the erosion system are subjected to two kinds of processing, and the pad (circular portion at the end of the pattern) is obtained. Extract the connection relationship Compares with design information and detects defects such as half-short and half-break.
  • the inspection rule that a conductor is determined to be defective when the conductor interval is less than the specified interval, or a defect when the conductor width is equal to or less than the specified width.
  • the conductors are cut to eliminate the conductor width below a specified value, and defects are detected. Therefore, when the expansion pattern is formed from the original wiring pattern, the expansion amount is the minimum conductor interval, and the contraction amount is the minimum pattern width.
  • the extraction processing of the connection relation means that a number (pad number) is assigned to the center of the pad, the pad number is propagated along the pattern, and when this arrives at another pad number, This is a method of storing the connection between the pad number and the pad number at the starting point.
  • the force S that extracts the connection relationship that pad number 1 is connected to pad numbers 2, 3, and 4 is extracted. Since the pad number ⁇ and the pad number 3 and the pad number ⁇ are connected to each other, by comparing the extracted connection relation with the design information, the pad number 1 and the pad number ⁇ are compared. It can be seen that there is a defect such as a short short or short between pad numbers 3 and 4.
  • FIG. 6 is a diagram showing an entire configuration of a detection algorithm of the wiring pattern inspection device.
  • a pattern detection unit 100 performs photoelectric conversion of an optical image from a print substrate, thereby transmitting a grayscale image of the surface of the print substrate. No. This grayscale image is sent to an expansion system and a contraction system.
  • the grayscale image of the wiring pattern is binarized 101, and the obtained binary pattern is dilated 110a as described above, and the dilation pattern is maintained in a connected relationship.
  • the data compression process 1 1 1a to reduce and change the image as it is, temporarily store it in the image memory 1 1 1 2.
  • the grayscale image of the wiring pattern is binarized 102, and the obtained binary pattern is reduced 1202 as described above.
  • the image is temporarily stored in the image memory 1 1 3.
  • the expansion pattern and the reduction pattern are read from the image memory to extract the connection relationship of each, and each extraction result is compared with the design information 1 15 to judge a defect 1 16. Based on the judgment result, the connected part including the defect in the dilation pattern and the contraction pattern is extracted 117, and the defect position is specified 118.
  • the detected grayscale image is binarized by a simple binarization method using a single binarization threshold.
  • a binarization threshold that could detect all system and under-system defects.
  • the present invention enables binarization 101 and 102 so that all of the above defects can be detected by processing in the expansion system and the contraction system.
  • binarization by three thresholds and binarization by a second derivative are used in combination, and the five types of thresholds for the binarization can be appropriately set.
  • the five types of thresholds will be described with reference to FIG.
  • FIG. 1 (a) shows a specific example of a wiring pattern on a printed circuit board, wherein 1 is a wiring pattern, 2 is a broken hairline, 3 is a pinhole, 4 is a hairline short, and 5 is a hairline short.
  • the scattered portion 6 is the substrate portion of the printed circuit board.
  • FIG. 3A it is assumed that the surface of the base portion 6 of the printed circuit board has high brightness and is bright, and a dark wiring pattern 1 having low brightness is formed on this surface.
  • hairline breaks 2 and pinholes 3 are generated in the wiring pattern 1, and a hairline short 4 is further provided between the wiring pattern 1 and another wiring pattern. It is assumed that scattering 5 has occurred on the surface of 6.
  • the low-level portion for the wiring pattern 1 and the high-level portion for the base portion 6 are read as shown in FIG. The portion where the level changes between the low-level portion and the high-level portion becomes the edge portion of the wiring pattern 1.
  • the presence of the hairline disconnection 2 in the dark wiring pattern 1 is brighter than the wiring pattern 1 part, but it is darker and thinner than the base part 6, and the closer to the brightness of the wiring pattern 1 . Therefore, the grayscale image signal 10 Then, as shown in Fig. 1 (b), the level of the hairline break 2 is slightly higher than the level of the wiring pattern 1. Also, the pinhole 3 has the brightness between the wiring pattern 1 and the base 6 as in the case of the hairline disconnection 2, but has a larger area than the hairline disconnection 2, so that the grayscale image signal 10 As shown in Fig. 1 (b), the level is higher than that of hairline break 2.
  • the hairline shorts 4 and the scattering 5 have a brightness close to that of the base material 6 because the periphery thereof is surrounded by the base material 6.
  • the brightness approaches the base material part 6. Therefore, in the grayscale image signal 10, as shown in FIG. 1 (b), the level of the hairline short 4 and the scattering 5 is lower than the level of the base 6, but the hairline break 2 and the pin It is higher than the level of the hole 3 and the level difference between them becomes larger as the difference in brightness (contrast) between the base 6 and the wiring pattern 1 becomes larger. Also in this case, since the scattering 5 has an area with respect to the hairline short 4, the level of the scattering 5 is lower than the level of the hairline short 4 in the grayscale image signal 10.
  • the signal level of the grayscale image signal 10 is significantly different between the shortage defect such as the hairline disconnection 2 and the pinhole 3 and the surplus defect such as the hairline short 4 and the scattering 5.
  • the conventional binarization method using a single binarization threshold a binarization pattern including all of these defects cannot be obtained.
  • the detection of the hairline disconnection 2 and the hairline short 4 uses a binarization method of the secondary differential signal of the grayscale image signal 10 together.
  • (c) shows the second derivative signal 11. Since the hairline break 2 in the grayscale image signal 1 has a steeper signal change than the pinhole 3, the hairline break 2 in the second derivative signal 1 1 as shown in Fig. 1 (c). The amplitude of the part is larger than that of the pinhole 3. Similarly, in the second derivative signal 11, the amplitude of the hairline short 4 is larger than that of the splash 5. From this, this second derivative signal 1
  • th 2 Hairline short detection threshold for the second derivative image
  • th3 Hairline disconnection detection threshold for the second derivative image
  • FIG. 1 (d) shows a binary pattern At obtained by binarizing the grayscale image signal 10 in FIG. 1 (b) with an appropriately set basic threshold value th1. If the brightness (shade value) of the signal is I, A!
  • FIG. 1 (h) shows a binary pattern AH obtained by binarizing the grayscale image signal 10 in FIG. 1 (b) with an appropriately set scattering detection threshold thH.
  • FIG. 1 (j) shows a binary pattern ⁇ _ obtained by binarizing the grayscale image signal 10 in FIG. 1 (b) with a properly set pinhole detection threshold thL. So, ⁇ (I ⁇ th)
  • Fig. 1 (i) shows a binary pattern A'2 obtained by binarizing the second derivative signal 11 in Fig. 1 (c) with a properly set hairline short detection threshold th2.
  • the second derivative is I " a , I, I, I" d
  • the secondary differential value I " a is obtained by causing the grayscale image signal 10 shown in Fig. 1 (b) to operate a 5X5 secondary differential operator in pixel units shown in Fig. 2 (a).
  • the second derivative values are expressed as I ⁇ b , I, and I " d , respectively, in the pixel unit shown in FIGS. 2 (b), (c), and (d) in the grayscale image signal 10.
  • Figure 1 (k) is an indication of the binary pattern A 3 obtained turned into binary in the secondary differential signal 1 1 an appropriately set Hearai Nsho over preparative detection threshold th 3 in FIG. 1 (c)
  • Figure 1 (k) is an indication of the binary pattern A 3 obtained turned into binary in the secondary differential signal 1 1 an appropriately set Hearai Nsho over preparative detection threshold th 3 in FIG. 1 (c)
  • the second derivative operator shown in Fig. 2 (a) reveals a pattern edge along the horizontal direction
  • the second derivative operator shown in Fig. 2 (b) is a pattern edge along the upward right direction
  • the second derivative operator shown in Fig. 2 (c) reveals the pattern edge along the vertical direction.
  • the second derivative operator shown in Fig. 2 (d) makes the pattern edge along the downward right direction visible.
  • the binary pattern A based on the reference threshold, as shown in FIG.
  • the value is "1" for the wiring pattern 1 and "0" for the substrate portion 6. That is, it is a signal whose level is inverted at the pattern edge.
  • the binary pattern AH based on the scattering detection threshold thH of the grayscale image 10 is “1” for defects such as the hairline shot 4 and the scattering 5 existing in the base material 6.
  • the signal component for the scattering 5 is included as a signal having a time width corresponding to the actual dimension of the width of the scattering 5.
  • the binary pattern AH may include not only the signal component for the scattering 5 but also the signal component for the hairline short 4, and the wiring pattern 1 always includes “1”. ".
  • a defect such as a broken hairline 2 and a pinhole 3 existing in the wiring pattern 1 is caused by the pin pattern detection threshold thL of the grayscale image 10 and the binary pattern Ad. It becomes “0", and by properly setting the pinhole detection threshold thL, the signal component for the pinhole 3 is included as a signal having a time width corresponding to the actual dimension of the width of the pinhole 3.
  • the binary pattern AL is always "0".
  • the differential binary pattern A2 of the second derivative pattern 11 with the hairline short detection threshold th2 is By properly setting the detection threshold t.h2, the signal component for hairline short 4 is included as a signal with a time width corresponding to the actual dimension of the width of this defect. However, depending on the steepness of the edge portion, the edge portion of the pinhole 3 and the scattering 5 / the edge portion of the wiring pattern 1 and the like are also included.
  • the differential binary pattern A2 of the second derivative pattern 11 with the hairline disconnection detection threshold th3 can be obtained by appropriately setting the hairline disconnection detection threshold th3, as shown in Fig. 1 (k).
  • the signal component for hairline break 2 is included as a signal of “0” with a time width corresponding to the actual size of the defect width, but depending on the steepness of the edge portion, pinhole 3 or Edges such as wiring pattern 1 will also be included.
  • the binary pattern A or A 3 is subjected to the logical AND operation to obtain a signal having a time width corresponding to the actual size of each defect of the hairline disconnection 2 and the pinhole 3.
  • a binary pattern (AL ⁇ A 3 ) containing the components is obtained.
  • a binary butterfly including signal components of a time width corresponding to the actual size of each of the defects of the hairline short 4 and the scattering 5 is given.
  • (AH + A 2 ) is obtained.
  • the edge of the wiring pattern 1 is not correctly detected. That is, the basic threshold value th1 is for detecting the edge portion of the wiring pattern 1, and by appropriately setting the basic threshold value th1, the edge portion of the wiring pattern 1 is detected at a correct position. Will be.
  • the level inversion of the binary pattern shown in Fig. 1 (d) represents the edge of the wiring pattern 1.
  • the signal is further divided in the time axis direction into a region of the wiring pattern 1 excluding the edge portion, an edge region including an edge portion of the wiring pattern 1, and a region of the base portion 6.
  • FIG. 1 (e) shows a binary pattern A NL representing the area of wiring pattern 1 (the area of wiring pattern 1 is also referred to as wiring pattern area ANL)
  • FIG. 1 (f) shows the edge of wiring pattern 1 binary pattern ANM representing the area of the section (the realm of the Ejji part also called an edge region ANM)
  • a first diagram (g) the binary pattern a NH representing the area of the base portion 6 (in this The region of the substrate portion 6 also represents the substrate portion region ANH ).
  • the areas A NL , ANM, and A NH are defined as follows: the number of effective pixels of “1” around the pixel of interest in the area dividing operator described later is N, and the determination value is N or NH as described later. (Equation 6).
  • a 3 is an operation for matching the level in the edge area with the level of ANAL ⁇ A 3 in the wiring pattern area.
  • ⁇ A 2 is an operation for aligning the level in the edge area and the level of ANH ⁇ (AH + A2) in the base material area when the binary pattern A 1 is inverted from the level shown in the figure.
  • AR (A N A A ⁇ 3 ) + ⁇ ⁇ ⁇ ⁇ (A t 'A 30 tens A t ⁇ A 3 )]
  • Equation 7 Shows this output A R in FIG. 1 (1).
  • Such a wiring pattern area AN edge area ANM, base material section The division into the area AN'H is performed by the binary threshold with the basic threshold th1 shown in Fig. 1 (d)!
  • the region division operator is operated to determine which of the regions A, ANM, and Anh the pixel of interest in the binary pattern belongs to.
  • This region division operator acts on the two-dimensional array of pixels in the binary pattern A, and shows how the target pixel is surrounded by the effective pixels in the vicinity as the determination criterion. It is determined whether the pixel of interest belongs to the area AN or ANM or ANH in accordance with.
  • FIG. 3 shows a specific example of a region division operator.
  • the effective pixels are pixels B on the circumference around the pixel of interest P, and it is determined whether or not these effective pixels B are "1".
  • the number N of effective pixels B is counted, and it is determined according to the count value N whether the target pixel P belongs to the area AN or ANM or ANH.
  • this region dividing operator is called an operator of size n X n.
  • This operator size is set according to the line width of the wiring pattern 1 and the edge width of the wiring pattern, and is an inspection apparatus for inspecting a printed circuit board having a wiring pattern having different line widths and edge widths.
  • an area dividing operator having an optimal size is provided in advance for each print board, and the area dividing operator to be used is changed depending on the printed board to be inspected.
  • FIG. 3 shows a region segmentation operator having a size of 7 ⁇ 7, 9 ⁇ 9, and 11 ⁇ 11.
  • the target pixel P is in the area of the wiring pattern, and all the effective pixels B are “0”.
  • the target pixel P can be determined to be in the area of the base material portion.
  • the judgment value NH is given a value corresponding to the width of the hairline short, and even if there is a hairline short, the area ANH of the base material portion is changed to the area of the wedge portion of the wiring pattern. ANM is not misjudged .
  • the effective pixel B is arranged on the circumference that is isotropically arranged with respect to the pixel of interest P.
  • the present invention is not limited to this.
  • the range can be changed as appropriate according to the graphic properties and specifications of the object to be inspected, such as all pixels in a circle centered on P and all pixels in a square centered on the pixel of interest.
  • Fig. 7 (a) shows the area division operator (here, the operator size is 5 X 5) whose size is equal to or less than the line width of wiring pattern 1 (here, this line width is 5 pixels).
  • the drawing shows the operation of crossing wiring pattern 1 in the right direction on the drawing, and it is assumed that the position of the area dividing operator with respect to wiring pattern 1 changes in the order of (i), ( ⁇ ), and (iii).
  • the ratio ⁇ 5Z12.
  • the ratio ⁇ becomes 1 and becomes the maximum, and the area dividing operator becomes the wiring pattern 1 ⁇ becomes smaller as it deviates from.
  • Fig. 7 (b) shows the case where the operator size is larger than the line width of wiring pattern 1 (here, this line width is assumed to be 5 pixels) (here, the operator size). 7 X 7). Also in this case, as in the case of FIG. 7 (a), the region dividing operator shows the operation of crossing the wiring pattern 1 in the right direction on the drawing, and the position of the region dividing operator with respect to the wiring pattern 1 is shown. Changes in the order of (a), (mouth), and (c).
  • the target pixel P is located at the center of the wiring pattern 1 in the width direction.
  • the area dividing operator has moved one pixel to the right with respect to the wiring pattern 1 (mouth)
  • ratio 1 1 Z 12.
  • the right side when the area dividing operator moves rightward by one pixel with respect to wiring pattern 1 (C), the right side
  • the region dividing operator is slightly shifted from the wiring pattern 1 to one side rather than the pixel of interest ⁇ is located at the center of the wiring pattern 1 in the width direction. Then, the ratio becomes larger, and thereafter, as the area dividing operator deviates from the wiring pattern 1, ⁇ becomes smaller. From the above, when the operator size is equal to or smaller than the line width of the wiring pattern 1, when the area dividing operator is within the wiring pattern 1, the ratio ⁇ becomes 1 and becomes the maximum, and the area operator starts from the wiring pattern 1.
  • ⁇ decreases monotonically as it deviates, but when the operator size is larger than the line width of the wiring pattern 1, the pixel of interest ⁇ is more than this at the center of the wiring pattern 1 in the width direction. If the position is slightly shifted, ⁇ becomes large, and the relationship between ⁇ and the positional relationship between the area dividing operator and the wiring pattern becomes unnatural.
  • FIG. 8 is a view for explaining the minimum size of a usable area dividing operator for the wiring pattern 1 on the printed board to be inspected.
  • the edge portion of the grayscale image signal 10 of the wiring pattern 1 has a finite period of a sloping waveform in which the brightness (grayscale value) changes continuously due to the blurring of the pattern, as shown in FIG. are doing.
  • the number of pixels of the brightness included in the brightness range from the brightness of the pinhole detection threshold thL to the brightness of the scattering detection threshold thH is hereinafter referred to as the brightness. It is called the number of changed pixels.
  • Fig. 8 (a) shows a binary pattern near the edge when the operator size> the number of pixels with brightness changes.
  • the area ANM of the edge determined by the area division operator is The edge E of the binary pattern Ai obtained at the basic threshold th1 only in the edge area A because the entire edge of the grayscale image signal 10 is included. Is obtained.
  • edge E L for this Ejji part in binary pattern AL obtained in the pinhole detection threshold thL is also even region ANH, binary resulting et al are in scattered detection threshold thH pattern Edges EH for this edge are generated in AH.
  • the size of the region dividing operation needs to be equal to or larger than the width of the edge portion of the wiring pattern 1.
  • the segmentation operator can only take discrete values of 7 ⁇ 7, 9 ⁇ 9, and 11 ⁇ 11, but the thresholds N H and NL must be set for the effective pixel count. Accordingly, it is possible to realize a region division operator having a size between such discrete actual sizes. In other words, when the threshold value NH, is made closer, the same effect as reducing the operator size can be obtained.
  • a pinhole defect is manifested at a low threshold thL
  • a scattering defect is manifested at a high threshold thH
  • hairline disconnection and hairline short are exclusively determined by the second derivative threshold.
  • the binarized output A R shown in the above (Equation 7) is obtained.
  • the above thresholds thl, thH, thL, th2, and th3 are In the case of the defect inspection apparatus shown in Fig. 6, the binarization means 101, 102 and the image display means 131, 1 for displaying the binarized image obtained by the above (Equation 7) are obtained. This is performed using 32.
  • the binarizing function can be switched.
  • AR (ANL ⁇ A i ⁇ A s) + ⁇ ANM ⁇ (A i ⁇ A s + A i ⁇ A 2) ⁇
  • AR AIA3 + A2-Ai-(ANM + ANH) + ANH
  • A A lA 3 + A 1A 2
  • a R A N LA L + ANMA 1 + A N HA H
  • a critical defect sample of each defect mode (that is, a defect type such as a broken hairline or a hairline short) is used as a reference.
  • the reference sample may be a real defect or a simulated defect.
  • hairline breaks and hairline shorts having the minimum width to be detected, half shorts having the minimum conductor spacing, semi-open defects having the minimum line width, and pinholes and scattering defects having the minimum detection size.
  • FIG. 9 shows an example of a setting standard of each binarization threshold in the expansion system and the contraction system of FIG.
  • the grayscale image having the above sample is supplied from the pattern detection means 100 to the binarization means 101, and the binarization pattern A obtained here is obtained.
  • R is displayed on the image display means 13 1, and the threshold value is adjusted to set an optimum threshold value.
  • the reference threshold th1 for pattern detection is such that the detection target is the pattern edge and half short (defects narrower than the minimum spacing specified for the conductor pattern spacing: Fig. 4).
  • the binarized pattern obtained at the reference threshold thl is expanded by the specified width as described above, the half shot always shoots.
  • Such a threshold value is used as a reference when determining the threshold value th H for scattering detection. Therefore, this threshold th1 is set so that the minimum conductor interval (not a defect) specified in the binarized pattern obtained by binarizing the grayscale image with the reference threshold th1 is detected to the actual size. Must be set.
  • the threshold value th2 is used to binarize the second derivative image, and hairline shorts and isolated points as surplus system defects are set as inspection target defects, and should be detected. It is set up to detect such defects of the smallest size at full scale.
  • a grayscale image of one sample is obtained, and is binarized using the reference threshold th1 as described above to obtain a binarized pattern.
  • a second derivative image of the grayscale image is obtained, and the threshold th2 This threshold value th2 is adjusted so that such a defect having the minimum size is binarized and detected in the actual size.
  • the threshold value thH is used to binarize the grayscale image to detect scattering as a surplus system defect, and the defect having the minimum size to be detected in the binarized image is the actual size.
  • the threshold value thH is used to binarize the grayscale image to detect scattering as a surplus system defect, and the defect having the minimum size to be detected in the binarized image is the actual size.
  • the threshold th3 is for detecting hairline breakage, which is an insufficient defect in the conductor pattern, and the threshold thL is an insufficient defect in the conductor pattern.
  • These thresholds th 3 and th L are not used in the expansion system because they are for detecting pinholes, and are set to the same values as those in the contraction system as an example.
  • the reference threshold thl for pattern detection is determined by detecting the edge of the pattern and the semi-disconnection (the defect whose conductor pattern width is smaller than the specified minimum width: see Fig. 4).
  • the threshold value is set so that this half-break is surely broken.
  • this threshold value thl is set so that the minimum conductor width (not a defect) defined by the binarization pattern obtained by binarizing the grayscale image with the reference threshold value thl is detected as the actual size. There is a need. This means that if there is no break, even if the width of the conductor pattern is the specified minimum, there will be no break when contracted.
  • the threshold value th 3 is used to binarize the second derivative image, and the hairline disconnection as an insufficient system defect is used as a defect to be inspected. Defects are set to be detected at full scale, but this requires a sample with a defect of that size.
  • a gray-scale image is obtained, and is binarized with the reference threshold th1 as described above to obtain a binarized pattern Ai.
  • a second derivative image of the gray-scale image is obtained, and this is obtained by using the threshold th3. This threshold th3 is adjusted so that such a defect having the minimum size by binarization is detected in the actual size.
  • the threshold value thL is used to binarize the grayscale image to detect a pinhole as a defect of insufficient system, and a defect having a minimum size to be detected in the binarized image is used. It is set to be detected in actual size. In this case, only the "1%" area of the binarized pattern of the binary image based on the threshold thL of the grayscale image is extracted so that the defect to be inspected is extracted and displayed on the image display means 132. To be supplied to the image display means 132.
  • the threshold th 2 is for detecting a hairline short which is a surplus defect in the conductor pattern
  • the threshold th H is for detecting a scattering which is a surplus defect in the conductor pattern.
  • these thresholds th2 and thH are not used, and are set to the same value as the expansion system as an example.
  • the threshold value th1 and the threshold value for detecting the hairline short Z isolated point are obtained by using the binarizing means 101 and the image displaying means 131.
  • th 2 and a threshold th H for scattering detection are set.
  • the reference threshold th l and the threshold value th l are set by using the binarization means 102 and the image display means 13 2.
  • a threshold th2 for hairline disconnection detection and a threshold thL for pinhole detection are set.
  • the threshold can be set according to each defect type, different minimum detection dimensions according to the threshold set for each defect type, that is, detection sensitivity according to the defect type. Can detect defects. As a result, defects detected with different detection sensitivities for each type of defect can be displayed on the screen, and information about the type and detection sensitivity of the defect and the position of each defect can be output to the outside.
  • the modulation of the image signal obtained by imaging the pattern to be inspected changes according to the density of the pattern.
  • the threshold can be set according to the type of each defect.
  • the minimum detection size of the defect is twice the pixel size, which is the logical detection limit. Can be set up to the size of. In other words, if the detection optical system is set so that the size of the detection pixel is 3 ⁇ m, Large defects can be detected, and if the size of the detected pixel is set to 2 // m, defects larger than 4 m can be detected.
  • the relationship between the detection dimensions of the target defect may be obtained using the binarization threshold as a parameter.
  • FIG. 10 shows an example of setting the threshold thL for detecting pinholes and the threshold thH for detecting scattering.
  • FIG. 10 (a) shows the detection size of this pinhole defect when the threshold thL is changed for a pinhole defect having a diameter of 25 m.
  • the detection size decreases as the threshold value thL is increased.
  • the threshold value thL must be set to 5 to accurately detect a pinhole defect. It can be seen that 0 gradation is sufficient.
  • the reason why the detected defect size changes depending on the threshold value is due to the modulation of the pattern waveform in the grayscale image.
  • the reference threshold thl a value obtained from the minimum conductor interval by the above procedure is used.
  • FIG. 10 (b) shows the detection size of the scattering defect when the threshold th H for the scattering defect having a diameter of 28 ⁇ m is changed.
  • the detection size increases as the threshold th H is increased.
  • the threshold th H must be 90 to 1 in order to accurately detect the scattering defect. It is sufficient to set the range of 100 gradations, and in particular, it is understood that the 100 gradations are optimal.
  • each binarized image and the collection of data on the detection size of the reference defect when the threshold value is used as a parameter are shown in FIG. This is done at 1, 1 32.
  • These image display means 13 1 and 13 2 can be constituted by, for example, a personal computer and a monitor.
  • FIG. 11 is a diagram showing a specific example of a display screen 200 on such image display means 13 1 and 13 2.
  • the functions of the image display means 13 1 and 13 2 include the storage of the binary image 201 when the respective thresholds are changed and the display function on the display screen 200.
  • Binarization means 101 and 102 are provided separately for the contraction system.
  • the binarization of the expansion system and the contraction system may be shared.
  • the parameters can be standardized by setting a binarization threshold after performing shading correction and level correction. In other words, this has the effect of minimizing the effects of changes in brightness that depend on changes in material and the characteristics of the detection system.
  • a pattern input by predetermined image input means is It is possible to detect binarization with high precision as precisely as possible, enabling more stable and precise inspection of pattern defects.
  • a limit value sample of the defect to be detected is used By doing so, it is possible to easily set the binarization threshold, and to obtain a wiring pattern inspection apparatus that can detect minute defects that were difficult to deal with conventionally. it can.

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  • General Physics & Mathematics (AREA)
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Abstract

Afin de visualiser un schéma d'interconnexion formé sur un support avec une grande précision, on combine logiquement une image binaire formée au moyen de trois seuils, à savoir un seuil de base th1, un seuil thL pour détecter une imperfection (par exemple un trou d'épingle), et un seuil thH pour détecter un autre défaut (par exemple un défaut de diffusion), avec une image binaire différentielle quadratique formée à l'aide de seuils différentiels quadratiques th2 et th3. On peut ainsi détecter notamment des découpes et des fissures, et saisir une image binaire précise du schéma d'interconnexion. On peut en outre définir séparément les conditions de détection des imperfections susmentionnées et des autres défauts, et donc fixer chaque seuil de manière optimale et détecter les micro-imperfections, généralement difficiles à détecter, de manière fiable, et ainsi procéder à une micro-inspection dudit schéma d'interconnexion.
PCT/JP1999/006138 1999-02-26 1999-11-04 Procede et dispositif d'inspection d'un schema WO2000052644A1 (fr)

Applications Claiming Priority (2)

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JP05161099A JP3581040B2 (ja) 1999-02-26 1999-02-26 配線パターン検査方法
JP11/51610 1999-02-26

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JP2002259948A (ja) 2001-03-02 2002-09-13 Tdk Corp 次処理決定方法、検査方法および検査装置
JP5080371B2 (ja) * 2008-06-09 2012-11-21 Ｊｆｅスチール株式会社 プレス部品の欠陥検出方法
JP6116099B2 (ja) * 2014-01-27 2017-04-19 株式会社 日立産業制御ソリューションズ 太陽光発電量予測装置及び領域分割マップ表示方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01255073A (ja) * 1988-04-01 1989-10-11 Sumitomo Metal Ind Ltd パターン検査方法及び装置
JPH05108800A (ja) * 1991-10-14 1993-04-30 Nippon Telegr & Teleph Corp <Ntt> 画像欠陥判別処理装置
JPH0666532A (ja) * 1992-08-19 1994-03-08 Shinko Electric Ind Co Ltd 製品検査支援システム
JPH1145919A (ja) * 1997-07-24 1999-02-16 Hitachi Ltd 半導体基板の製造方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01255073A (ja) * 1988-04-01 1989-10-11 Sumitomo Metal Ind Ltd パターン検査方法及び装置
JPH05108800A (ja) * 1991-10-14 1993-04-30 Nippon Telegr & Teleph Corp <Ntt> 画像欠陥判別処理装置
JPH0666532A (ja) * 1992-08-19 1994-03-08 Shinko Electric Ind Co Ltd 製品検査支援システム
JPH1145919A (ja) * 1997-07-24 1999-02-16 Hitachi Ltd 半導体基板の製造方法

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