JPH11328410A - Method for positioning pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain positioning for correction when the local distortion of an inspecting work is within an allowable range. SOLUTION: The whole positioning of a master pattern being a reference and a pattern to be measured which is image picked-up by a camera is performed (a step 106). Plural divided areas are set in the pattern to be measured, and the corresponding divided areas are set in the master pattern. The coordinates of at least four positioning marks are obtained in the divided areas of the pattern to be measured, and the coordinates of the corresponding positioning mark are obtained in the corresponding divided areas of the master pattern. A coordinate transformation formula between the pattern to be measured and the master pattern is decided from those coordinates, and the divided areas of the master pattern are transformed by the coordinate transformation formula, and the positioning of the master pattern and the pattern to be measured is performed for each divided area (a step 107).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection method for inspecting a pattern formed on a green sheet or a film carrier, and more particularly, to an alignment method for aligning a master pattern with a pattern to be measured. .

[0002]

2. Description of the Related Art Conventionally, PGA (Pin Grid Array) has been known as a mounting technique suitable for a demand for increasing the number of pins of ICs and LSIs. In PGA, a ceramic substrate is used as a base of a package for attaching a chip, and wiring is performed to a lead wire extraction position. To make this ceramic substrate, a so-called green sheet made by kneading alumina powder with a liquid binder is used, and a paste containing a high melting point metal is screen-printed on the green sheet. By firing such a sheet, so-called simultaneous firing, in which the green sheet is sintered and the paste is metallized, is performed.

[0003] As another mounting technique, TAB is used.
(Tape Automated Bonding) is known. TAB method is a polyimide film carrier (TAB tape)
The copper foil pattern formed thereon is joined to the electrode of the IC chip to form an external lead. The copper foil pattern is formed by attaching a copper foil to a film with an adhesive and etching this.

In such a green sheet or film carrier, a pattern is visually inspected by a human using a microscope after the pattern is formed. However, visual inspection of fine patterns requires skill and
There was a problem of overworking the eyes. Therefore, as an alternative to the visual inspection, a technique has been proposed in which a pattern formed on a film carrier or the like is picked up by a TV camera and automatically inspected (for example, JP-A-6-273132, JP-A-7-273132). No. 110863).

FIGS. 8 and 9 are diagrams for explaining a conventional inspection method for detecting a disconnection described in Japanese Patent Application Laid-Open No. 6-273132. A master pattern created by imaging the pattern to be measured determined as a non-defective product is registered as a set of straight lines indicating pattern edges. The pattern to be measured is input as a set of edge data (edge coordinates) indicating a pattern edge extracted from a grayscale image obtained by capturing the pattern. Then, the extracted edge data n1, n2, n3,... Of the pattern to be measured are associated with the straight lines of the master pattern. In order to perform this association, as shown in FIG. 8, the bisectors A2 ', A3', which divide the angles formed by the continuous straight lines A1 and A2, A2 and A3.・ ・

The lines around the straight lines A1, A2, A3,... Of the master pattern are divided into areas respectively belonging to the straight lines A1, A2, A3,. .. Exist in each area are associated with the straight lines A1, A2, A3,... Of the master pattern to which the area belongs. . For example, in FIG. 8, the edge data n1 to n3 are associated with the straight line A1, and the data n4 to n6 are associated with the straight line A2. Next, the edge data of the pattern to be measured is compared with the master pattern to check whether the pattern to be measured is disconnected.

This inspection is realized by a labeling process for tracing the pattern edge by tracing the connected edge data n1 to n9 of the pattern to be measured, as shown in FIG. At this time, since the edge data is not connected at the disconnected portion due to the disconnection generated at the leading end of the pattern to be measured, there is no edge data corresponding to the straight lines A3 to A5 of the master pattern. Thus, the disconnection of the pattern to be measured can be detected.

FIG. 10 is a diagram for explaining a conventional inspection method for detecting a short circuit described in JP-A-6-273132. First, in the inspection area 20 in which the master pattern and the pattern to be measured are cut out to a predetermined size, the connected edge data of the pattern to be measured is tracked. Thereby, each edge data of the pattern to be measured is n1 to n
18 and are sequentially labeled. However, a master pattern Mb composed of two opposing straight lines as well as a master pattern Mb composed of two opposing straight lines indicating a pattern edge include:
Edge data n8 and n17 are not registered. Thus, a short circuit of the pattern to be measured can be detected.

FIG. 11 is a view for explaining a conventional inspection method for detecting a defect or a protrusion described in Japanese Patent Application Laid-Open No. Hei 7-10863. First, a perpendicular line perpendicular to the center line L is drawn, and the length between intersections where the perpendicular line intersects the straight lines A1 and A2 indicating the edges of the master pattern is determined in advance as the width W0 of the master pattern. Next, in an actual inspection, a distance between the edge data opposing the center line L of the master pattern is determined from the edge data n of the pattern to be measured. This is the width W of the pattern to be measured, and the loss or protrusion of the pattern to be measured is detected by comparing this with the width W0 of the master pattern.

However, in the pattern inspection apparatus using such an inspection method, there is a problem that the pattern inspection takes a long time because a detailed inspection is performed by software on the whole of the pattern to be measured by comparison with the master pattern. . Therefore, a pattern inspection apparatus capable of performing inspection in a short time has been proposed (for example, Japanese Patent Application No. 8-30280).
No. 7). In the pattern inspection apparatus described in Japanese Patent Application No. 8-302807, a defect candidate of a measured pattern is detected by hardware (primary inspection), and only a predetermined small area including the detected defect candidate is inspected by software. Secondary inspection), it is possible to inspect the defect of the pattern to be measured at a higher speed than before. By the way, in any of the above pattern inspection apparatuses, in order to compare a measured pattern captured by a camera with a master pattern,
It is necessary to align the master pattern and the pattern to be measured. This alignment has been performed by matching the position of a positioning mark provided in advance on the master pattern with the position of the corresponding positioning mark of the pattern to be measured.

[0011]

However, in the above-described alignment method, if the inspection work has a local distortion such as expansion and contraction, it is assumed that the alignment with the master pattern has been completed as a whole. Also, since there is a local deviation from the master pattern, this deviation may be detected as the above-mentioned defect candidate. In this case, even if the local distortion of the inspection work is within the allowable range, there is a problem that the inspection time is required because the secondary inspection is performed. The present invention has been made to solve the above-described problems, and provides a positioning method that can omit a secondary inspection and reduce an inspection time if local distortion of an inspection work is within an allowable range. The purpose is to provide.

[0012]

According to the present invention, the entirety of the master pattern and the measured pattern is adjusted by aligning the positions of the positioning marks with respect to the entire area of the measured pattern and the master pattern. After performing the positioning, a plurality of divided areas are set in the pattern to be measured, and a plurality of corresponding divided areas are set in the master pattern, and at least four points are positioned in the divided areas of the pattern to be measured. The coordinates of the mark are obtained, and the coordinates of at least four corresponding positioning marks are obtained in the corresponding divided area of the master pattern.
From these coordinates, a coordinate conversion formula between the pattern to be measured and the master pattern is determined, and the divided regions of the master pattern are converted by the above coordinate conversion formula, so that the alignment of the master pattern and the pattern to be measured is performed for each divided region. It is something to do. The coordinates of at least four positioning marks are obtained in the divided area of the pattern to be measured, and the coordinates of at least four positioning marks corresponding to the coordinates are obtained in the corresponding divided area of the master pattern. By determining the coordinate conversion formula between the patterns and converting the divided region of the master pattern by the coordinate conversion formula, it is possible to correct a subtle displacement between the divided region of the master pattern and the divided region of the pattern to be measured. As described above, by performing the alignment of the master pattern and the pattern to be measured for each divided region, if the local distortion of the inspection work is within the allowable range, the inspection can be performed by absorbing the distortion. In addition, a deviation between the result of inputting the coordinates of the positioning mark of the pattern to be measured in the coordinate conversion formula and the coordinates of the corresponding positioning mark of the master pattern is determined for each mark, and the deviation is determined by a predetermined value. The above-mentioned coordinate conversion formula is repeated by repeatedly excluding the positioning mark larger than the threshold value from both the pattern to be measured and the master pattern and obtaining the coordinate conversion formula again until all deviations become equal to or less than a predetermined threshold value. Is determined. Further, as described in claim 3, each divided area is set so that the left, right, top and bottom overlap with other divided areas.

[0013]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart illustrating an inspection method according to an embodiment of the present invention, and FIG. 2 is a block diagram of a pattern inspection apparatus used in the inspection method. In FIG. 2, 1 is a green sheet serving as an inspection work, 2 is an XY table on which the green sheet 1 is placed,
3 is a line sensor camera for imaging the green sheet 1,
Reference numeral 4 denotes a first output for performing a primary inspection for detecting a defect candidate of the pattern to be measured and outputting address information indicating a position of the defect candidate.
5 is a second image processing apparatus for obtaining an error between a measured pattern and a master pattern for a predetermined area including a defect candidate based on the address information and performing a second inspection of the measured pattern. A host computer 7 for controlling the whole is a display device for displaying inspection results.

First, a master pattern created in advance before inspection will be described. Host computer 6
Reads out, by a magnetic disk device (not shown), design value data (hereinafter referred to as CAD data) of a green sheet created by a CAD (Computer Aided Design) system and written on, for example, a magnetic disk (step 101 in FIG. 1). Then, pattern edge data is extracted from the read CAD data. Edge data is
A set of pixels “1” indicating a pattern edge. Then, the area surrounded by the pixel “1” indicating the pattern edge is painted with “1”, and the pattern painted with this pixel “1” (the background other than the pattern is “0”) is used as the first reference to be inspected. (Step 10 in FIG. 1)
2).

As described above, in the present embodiment, in order to create an accurate master pattern, CAD data that has become a master in manufacturing the green sheet 1 is used. Next, the host computer 6 creates a second master pattern for detecting loss or disconnection and a third master pattern for detecting protrusions or short circuits from the first master pattern as follows (step 103 in FIG. 1). . FIG. 3 is a diagram for explaining a method of creating the second and third master patterns, and shows a part of the first master pattern.

First, as shown in FIG. 3A, the first master pattern is contracted in a direction perpendicular to its center line,
A second master pattern M1 is created. This is because opposing straight lines A1 and A1 indicating both edges of the first master pattern
4 (center line is L1) and the distance between A2 and A3 (center line is L2) are narrowed to narrow the first master pattern.

The accuracy of defect detection by the second master pattern M1 is determined by how much the first master pattern is contracted. For example, when it is desired to recognize a defect when there is a defect exceeding 1/5 of the width of the first master pattern, the width of the second master pattern M1 is set to 3/5 of the width of the first master pattern. What is necessary is just to reduce it. It goes without saying that the detection accuracy may be determined in pixel units or actual dimensions. Thus, the second master pattern M1 for detecting loss or disconnection is created.

Subsequently, as shown in FIG. 3 (b), the first master pattern is expanded in a direction perpendicular to the center line to create a third master pattern M2. This corresponds to the opposite straight line A5 indicating both edges of the first master pattern.
And A8 (center line is L3), A6 and A7 (center line is L
4), A9 and A12 (center line is L5) and A10 and A1
1 (the center line is L6), and the first master pattern can be made thicker by widening the respective intervals.

However, actually, the third master pattern M2
Is a master pattern M composed of straight lines A5 to A8.
a and a region (base portion where no pattern exists) sandwiched between two patterns generated by expanding the master pattern Mb including the straight lines A9 to A12.

The accuracy of defect detection by the third master pattern M2 is determined by how much the first master pattern is expanded. For example, when it is desired to recognize a defect when there is a defect exceeding 1/5 of the width of the first master pattern, the width of the third master pattern M2 is set to 7/5 of the width of the first master pattern. It should just be expanded as follows. The fact that the detection accuracy may be determined in pixel units or actual dimensions is the same as in the second master pattern. Thus, a third master pattern M2 for detecting a protrusion or a short circuit is created.

Next, the inspection of the pattern to be measured will be described. First, the green sheet 1 is imaged by the camera 3. Then, the first image processing device 4 digitizes the grayscale image output from the camera 3 and temporarily stores it in an internal image memory (not shown) (step 10).
4). Since the camera 3 is a line sensor in which pixels are arranged in the X direction, the XY table 2 or the camera 3 is moved in the Y direction (here, the table 2
2D image data is stored in the image memory.

Subsequently, the image processing device 4 binarizes the grayscale image of the measured pattern stored in the image memory (step 105). The grayscale image data of the pattern to be measured includes the pattern and the other background (a base material such as a green sheet). However, since there is a density difference between the pattern and the background, the density value of the pattern and the background If a value between the density values is set as a threshold value, the pattern is converted to “1” and the background is converted to “0”. In this way, it is possible to obtain a pattern to be measured in which the pattern edge and the inside thereof are filled with the pixel “1”.

Next, the image processing apparatus 4 aligns the entire binarized pattern to be measured with the entire master pattern (step 106). FIG. 4 is a diagram for explaining this alignment method. First, the image processing device 4
In the pattern to be measured P stored in the image memory,
At the time of creating the CAD data, three or more positioning marks a provided in advance are designated as shown in FIG.
In the first master pattern M sent from the host computer 6, the corresponding positioning marks b are designated as shown in FIG.

Then, for each of the pattern to be measured P and the master pattern M, the distances DXp and DXm between the two positioning marks arranged in the X direction are obtained. The distance between marks is the distance between the centers of gravity of two positioning marks.

Subsequently, an enlargement / reduction ratio (DXp / DXm) is calculated from the obtained distance between the marks, and the distance between the marks of the master pattern is made to match the distance between the marks of the pattern to be measured by the enlargement / reduction ratio. , The master pattern M is enlarged or reduced in all directions. Next, for each of the pattern P to be measured and the master pattern M ′ whose magnification / reduction has been corrected, the distance D between the two positioning marks arranged in the Y direction is determined.
Yp and DYm are obtained as shown in FIGS.

The relative speed between the line sensor camera 3 and the green sheet 1 (XY table 2) is adjusted so that the distance between marks of the pattern to be measured matches the distance between marks of the master pattern. Is imaged again.
The image resolution in the Y direction is determined by the pixel size of the camera 3 and the relative speed. Therefore, by changing the moving speed of the XY table 2 or the line sensor camera 3, the image resolution in the Y direction can be adjusted, and the distance between marks can be matched.

Next, based on the positioning mark positions of the pattern P 'to be measured obtained by imaging in this way and the positioning mark positions of the master pattern M' whose enlargement / reduction has been corrected, FIG.
As shown in (e), the angle shift θ between the patterns P ′ and M ′ is obtained, and the master pattern M ′ is removed so that the angle shift is eliminated.
To rotate. Finally, the positions of the master pattern M ′ and the pattern to be measured P ′ are aligned so that the mark positions match each other.

As described above, for each of the pattern to be measured and the master pattern, the distance between the two positioning marks arranged in the X direction is obtained, and the master pattern is enlarged or reduced so that the obtained distance between the marks matches. For each of the measured pattern and the enlarged / reduced master pattern, the distance between the two positioning marks arranged in the Y direction is determined, and the relative speed between the line sensor camera and the measured pattern is determined so that the determined distance between the marks matches. Is adjusted, the pattern to be measured is imaged again, the angular deviation between the imaged measured pattern and the master pattern subjected to the enlargement / reduction correction is obtained, and the master pattern is rotated so as to eliminate the angular deviation. The position of the pattern and the pattern to be measured can be matched. As described above, in the present embodiment, the image resolution in the Y direction is adjusted by changing the capturing speed of the camera 3 with respect to the image resolution in the X direction determined by the number of pixels of the line sensor camera 3, and thereby the vertical ( The ratio of Y) to the width (X) can be 1: 1.

In an actual inspection, the ratio of length and width may not be completely 1: 1. For example, a pattern to be screen-printed on a green sheet may be printed in a state of being elongated depending on a printing direction. Therefore, in a pattern in which a good product has an elongation within an allowable range with respect to the standard, the ratio of length to width is not completely 1: 1. In the present embodiment, since the distance between marks in the Y direction is made to match by changing the capture speed of the camera 3, patterns to be measured having different vertical and horizontal scales within the allowable range can be made to match the master pattern. The position of the pattern can be automatically corrected for the change in the pattern position at the time.

Next, the image processing apparatus 4 performs positioning of the pattern to be measured and the master pattern for each divided region (step 107). FIG. 5 is a flowchart showing a positioning method for each divided area, and FIG. 6 is a diagram for explaining the positioning method.

First, the image processing apparatus 4 sets a plurality of divided areas Em in the first master pattern M as shown in FIG. 6A, and sets a plurality of divided areas Ep corresponding thereto in FIG. Set in the pattern to be measured P as in b),
A single divided region Em is cut out from the master pattern M, and a corresponding divided region Ep is cut out from the pattern to be measured P (step 201 in FIG. 5). The position and size of each divided area are set in advance. Further, the size of each divided region may not be constant.

Subsequently, the image processing apparatus 4 designates four or more preset positioning marks Fm in the divided area Em of the master pattern M as shown in FIG. Fp is designated in the corresponding divided area Ep of the pattern P to be measured as shown in FIG. 6D (step 202). In FIG. 6, the positioning marks Fm1, Fm2, Fm3, Fm
The positioning marks in the divided areas Ep corresponding to m4, Fm5, and Fm6 are Fp1, Fp2, Fp3, and Fp, respectively.
4, Fp5 and Fp6. Then, the image processing device 4
Are the positioning marks Fm1 to Fm6, Fp1 to Fp6
Is calculated (step 203).

Next, the image processing device 4 calculates a coordinate conversion equation between the pattern to be measured and the master pattern by using the coordinates of the positioning marks Fm1 to Fm6 and the coordinates of the corresponding positioning marks Fp1 to Fp6. It is determined by the least squares method (step 204). Xm = AXp + BYp + C Ym = DXp + EYp + F (1)

In equation (1), Xm and Ym are the X and Y coordinates of the master pattern, Xp and Yp are the X and Y coordinates of the measured pattern, and A, B, C, D, E and F are constants. Next, the image processing device 4 performs positioning marks Fp1 to Fp6.
The coordinates Xm and Ym are calculated by substituting the coordinates of an arbitrary positioning mark among them, for example, the mark Fp1 into the coordinate conversion formula of Expression (1) as Xp and Yp. Then, a deviation between the coordinates of the positioning mark Fm1 corresponding to the positioning mark Fp1 substituted into the coordinate conversion formula and the calculated coordinates Xm, Ym is obtained for each X, Y coordinate. The calculation of such a deviation is performed for each positioning mark (step 205).

Subsequently, the image processing device 4 determines whether each of the calculated deviations is larger than a predetermined threshold (Step 206). When all the deviations are equal to or smaller than the predetermined threshold value, it is determined that the distortion of the divided region Ep of the pattern to be measured is within the allowable range, and the derived coordinate conversion formula is appropriate, and this coordinate conversion formula is used. The coordinate conversion of the master pattern in the divided area Em is performed (Step 207).

If all the deviations are larger than the predetermined threshold value, it is determined that the distortion of the divided region Ep of the pattern to be measured is out of the allowable range, and that the green sheet 1 to be inspected is defective (step). 208). On the other hand, when the deviation smaller than the threshold value and the deviation larger than the threshold value coexist, the image processing device 4 excludes the positioning mark whose deviation is larger than the threshold value, for example, the mark Fp6 and the corresponding positioning mark Fm6. After that (step 209), the coordinate conversion equation of equation (1) is obtained again from the coordinates of the remaining positioning marks Fm1 to Fm5 and Fp1 to Fp5 (step 204).

Steps 204 to 206, 2 as described above
Steps 08 and 209 are repeated until each deviation becomes equal to or less than a predetermined threshold value. In this manner, the coordinate conversion equation of equation (1) is determined, and the conversion of the master pattern in step 207 can be performed. The use of a coordinate transformation equation such as equation (1) means that a so-called affine transformation is performed, whereby the divided areas Em and E
The displacement of p can be corrected.

The second and third master patterns correspond to the first and second master patterns.
Since the master pattern is created from the first master pattern, the alignment of the first to third master patterns with the pattern to be measured may be performed once using the first master pattern.

Further, in order to obtain the coordinate conversion equation of the equation (1), at least three positioning marks are required for each of the master pattern and the pattern to be measured. However, since the accuracy of the coordinate conversion formula deteriorates with every three points, specify the positioning marks of at least four points and exclude the positioning marks whose deviation is larger than the threshold from the derivation of the coordinate conversion formula. ing. Therefore, even if the positioning marks are three points each for both the master pattern and the pattern to be measured, if each deviation does not become less than the threshold value, it is not possible to obtain the coordinate conversion formula by setting the positioning marks two points at a time. Also in this case, it is determined that the green sheet 1 to be inspected is defective.

Next, the image processing apparatus 4 compares the divided area of the pattern to be measured with the corresponding divided areas of the second and third master patterns and performs a primary inspection of the pattern to be measured (step S1). 108). FIG. 7 is a diagram for explaining this inspection method.

First, as shown in FIG. 7A, the divided area Ep of the pattern P to be measured is compared with the corresponding divided area Em of the second master pattern M1 whose position has been corrected by the coordinate conversion formula. However, what is actually compared is the pattern NP obtained by logically inverting the pattern P to be measured and the second master pattern M1. That is, in the example of FIG. 7A, the portion other than the pattern NP indicated by the satin finish is the pattern to be measured P.

Pattern NP and second master pattern M1
Is obtained, the result of the logical product differs depending on whether the pattern P to be measured has a defect or a disconnection. For example, when the pattern to be measured P has “1” as its value and the master pattern M1 has “1”, if the pattern to be measured P has no loss or disconnection, the pattern NP and the master pattern M1 Since there is no overlap, the result of the logical product is “0”.

On the other hand, if there is a defect in the pattern P to be measured as shown in FIG. 7A, the pattern NP and the master pattern M1 overlap at this portion, and the result of the logical product is "1".
Becomes This is the same when the pattern to be measured has a disconnection. In this way, it is possible to detect loss or disconnection of the pattern to be measured. Then, the image processing device 4
Stores the position where the result of the logical product becomes “1” and is recognized as a defect candidate.

Subsequently, as shown in FIG. 7B, the divided area Ep of the pattern to be measured P and the third master pattern M2
Is compared with the corresponding divided region Em whose position has been corrected by the above coordinate conversion formula. Similarly to the above, when the logical product of the measured patterns Pa and Pb and the third master pattern M2 is obtained, the result of the logical product differs depending on whether the measured patterns Pa and Pb have a protrusion or a short circuit. That is, when there is no protrusion or short circuit in the patterns Pa and Pb to be measured, the result of the logical product is “0”.

On the other hand, if the pattern to be measured Pa has a projection as shown in FIG. 7B, the pattern to be measured Pa and the master pattern M2 overlap at this portion, and the result of the logical product is "1". . Similarly, if the patterns Pa and Pb to be measured are short-circuited, the result of the logical product is “1”. Thus, a protrusion or a short circuit of the pattern to be measured can be detected. Then, the image processing device 4 stores the position where the result of the logical product becomes “1” and is recognized as a defect candidate.

In FIGS. 3 and 7, the master patterns M1 and M2 are shown as having a value "1" not only for the edge but also for the inside, but the inside is "1".
When the master patterns M1 and M2 are created by the host computer 6, only the edges are used, and the image processing device 4 that receives the master patterns M1 and M2 sets the inside of the edges to "1". It may be painted out.

After performing such a primary inspection, the image processing device 4 outputs the stored position of the defect candidate as address information. The second image processing device 5 performs processing when a defect candidate is detected by the first image processing device 4 (step 1).
09) For a region of a predetermined size smaller than the divided region centered on the defect candidate at the position indicated by the address information, the measured pattern is compared with the first master pattern to determine an error, thereby obtaining an error. A secondary inspection of the pattern is performed (step 110). This inspection method is the same as the above-described conventional method shown in FIGS.

The above steps 107 to 110 are repeated until there are no unexamined divided areas (step 11).
1), for each divided area. The logical product processing of the measured pattern and the second and third master patterns can be realized by hardware, and only the predetermined area including the detected defect candidate is compared with the measured pattern requiring a long processing time and the first master pattern. Since the inspection is performed, the pattern to be measured can be inspected at a high speed.

However, if there is a local distortion such as expansion and contraction in the green sheet 1, the conventional pattern inspection method causes a local deviation from the master pattern, and this deviation is detected as a defect candidate. Therefore, even if the local distortion of the green sheet 1 is within the allowable range, the secondary inspection is performed, and the inspection time is reduced.

On the other hand, in the present embodiment, if the local distortion of the green sheet 1 is within the allowable range (that is, the deviation is equal to or less than the threshold), the alignment for each divided area by the coordinate conversion formula is performed. As a result, local distortion of the green sheet 1 is absorbed, and this distortion is not detected as a defect candidate. 6 (a) and 6 (b)
Although there is no overlap between the divided regions, the actual divided regions are set so that the left, right, top and bottom overlap with other divided regions. This is to check the connection between the divided areas. Further, in the present embodiment, the inspection of the next divided area is performed after the inspection of one divided area is completed. However, if a plurality of divided areas are inspected in parallel, it is impossible to perform a higher-speed inspection. Needless to say.

[0051]

According to the present invention, as described in claim 1, if the local distortion of the inspection work is within an allowable range,
The local distortion of the inspection work can be absorbed by the alignment of each divided region by the coordinate conversion formula, and a fine displacement between the divided region of the master pattern and the divided region of the pattern to be measured can be corrected. Therefore, if the local distortion of the inspection work is within the allowable range, the distortion will not be detected as a defect candidate, and the secondary inspection due to the distortion will not be performed, thereby shortening the inspection time. can do.

Further, the deviation between the result of inputting the coordinates of the positioning mark of the pattern to be measured in the coordinate conversion formula and the coordinates of the corresponding positioning mark of the master pattern is obtained for each mark. It is repeated until all deviations become equal to or less than a predetermined threshold value by repeatedly excluding a positioning mark having a value larger than a predetermined threshold value from both the pattern to be measured and the master pattern and obtaining a coordinate conversion expression again. Is determined, the accuracy of the coordinate conversion formula can be improved, and highly accurate positioning can be performed. When all the deviations are larger than the predetermined threshold value, the distortion of the divided area of the pattern to be measured is out of the allowable range, and it can be determined that the inspection work is defective.

Further, by setting each of the divided areas so that the right, left, top and bottom overlap with other divided areas, it is possible to determine whether or not the distortion at the boundary between the divided areas is within the allowable range. Can be determined by the deviation of a plurality of adjacent divided regions.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an inspection method according to an embodiment of the present invention.

FIG. 2 is a block diagram of a pattern inspection apparatus.

FIG. 3 is a diagram for explaining a method of creating second and third master patterns.

FIG. 4 is a diagram for explaining a method of aligning the pattern to be measured and the master pattern as a whole;

FIG. 5 is a flowchart illustrating a method for aligning a pattern to be measured and a master pattern for each divided region.

FIG. 6 is a diagram for explaining a method of aligning a pattern to be measured and a master pattern for each divided region.

FIG. 7 is a diagram for explaining a primary inspection method based on comparison with second and third master patterns.

FIG. 8 is a diagram for explaining a conventional inspection method for detecting disconnection.

FIG. 9 is a diagram for explaining a conventional inspection method for detecting disconnection.

FIG. 10 is a diagram for explaining a conventional inspection method for detecting a short circuit.

FIG. 11 is a view for explaining a conventional inspection method for detecting a defect or a protrusion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Green sheet, 2 ... XY table, 3 ... Line sensor camera, 4 ... First image processing apparatus, 5 ... Second image processing apparatus, 6 ... Host computer, 7 ... Display device.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FIG06F 15/70 455A

Claims (3)

[Claims] 1. A pattern inspection method for inspecting a measured pattern by comparing a master pattern serving as a reference with a measured pattern captured by a camera. After positioning the master pattern and the measured pattern as a whole by aligning the positions of the positioning marks with respect to the entire area of the measured pattern and the master pattern, setting a plurality of divided areas in the measured pattern Along with
A plurality of divided areas corresponding to this are set in the master pattern, the coordinates of at least four positioning marks in the divided area of the pattern to be measured are obtained, and the coordinates of at least four corresponding positioning marks are determined in the master pattern. In the corresponding divided area of, the coordinate conversion formula between the measured pattern and the master pattern is determined from these coordinates,
A pattern alignment method, wherein a position of a master pattern and a pattern to be measured are aligned for each of the divided regions by converting a divided region of the master pattern using the coordinate conversion formula. 2. The pattern alignment method according to claim 1, wherein a deviation between a result of inputting the coordinates of the positioning mark of the pattern to be measured in the coordinate conversion formula and the coordinates of the corresponding positioning mark of the master pattern is determined for each mark. Calculating the coordinate conversion formula again by excluding the positioning mark whose deviation is larger than the predetermined threshold from both the pattern to be measured and the master pattern until all the deviations are equal to or smaller than the predetermined threshold. And determining the coordinate conversion formula according to the following formula: 3. The pattern alignment method according to claim 2, wherein each of the divided areas is set so that the left, right, top and bottom overlap with other divided areas.