JPH042951A - Pattern inspection apparatus - Google Patents

Abstract

PURPOSE:To extract only a true defect by providing a binarizing circuit, a circumference masking circuit, an inspecting position detecting circuit, a circle masking circuit, a hole detecting circuit, a filling circuit and a hole defect identifying circuit. CONSTITUTION:A binarizing circuit 2 converts an input image into binary images consisting of 0- and 1-patterns, while a circumference masking circuit 3 produces a circular inspection mask. An inspecting position detecting circuit 4 detects an optional position where all points on the circumference mask are in 1-patterns, while a circle masking circuit 5 detects whether or not there is a 0-pattern in the circular mask. A hole detecting circuit 6 outputs a 0-pattern signal, if it is output from the circuit 5 on the detection position of the circuit 4, as hole positions. A filling circuit 7 converts an inner part at the detecting position of the circuit 4 all into 1-patterns. A terminal detecting circuit 8 scans circular masks larger than width of patterns to be inspected while synchronizing with filled images so as to detect the positions entirely filled with 1-patterns on the inside. A hole defect identifying circuit 9 does not identify a hole as a hole defect if a signal has been output from the circuit 6 at the detected terminal position.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pattern inspection device.

[Conventional technology]

As for the conventional technology, for example, Muto, Ando "Automation of Visual Inspection of Printed Circuit Boards" 9 Mechanical Design, Vol. 29, No. 2,
1) There is a method of using a dedicated mask as shown in 1) 87-96.1985.

FIG. 7 is a diagram for explaining a hole defect inspection method using a conventional inspection mask.

If the pattern representing the hole defect 20 is "0", when the center is on the B0" pattern, there are eight "1!" extending radially. The I length sensor M O-M 7 counts and measures the number of pixels until the 01+ pattern is interrupted, and calculates the direct sum of the counter lengths of the opposing length measurement sensors (MO
+M4. , M1+M5. M2+Mt3. If all of M3+M7) are smaller than the pattern spacing tolerance, hole defect 2
Detected as 0.

[Problem to be solved by the invention]

The conventional pattern inspection device described above: (1) Detects a hole defect on a pattern with a narrow pattern width as a defect, and does not detect a hole defect on a pattern with a large pattern width, for example, at the end position of the pattern, as a defect. Since there is no such function and all hole defects are detected, the number of defective areas detected becomes enormous, and the defects must be re-recognized.

(2) Since the defect is detected at each position of the pixels that make up the pattern defect, even though the hole is the same, the signal strength of the defect is output depending on the size of the hole. There is a drawback that it is necessary to add another determination circuit in order to group these defects together as one defect.

(3) It is possible to inspect the pattern spacing only in a predetermined direction, which has the disadvantage that it is necessary to correct the pattern inclination with high precision.

[Means to solve the problem]

The pattern inspection device of the first invention scans the pattern to be inspected with a photoelectric conversion scanner and reads out an input image with 0"
a binarization circuit for converting into a binary image of ““+;
A circumferential mask circuit generates a circular inspection mask in synchronization with a value image, and scans the circumferential mask on the binary image in a raster scan manner so that all points on the circumferential mask are 1"'
an inspection position detection circuit that detects any position of the pattern;
a circular mask circuit that generates a circular mask on the binary image and detects whether a 0" pattern exists within the circular mask;
A hole detection circuit that outputs a signal as a hole position when the circular mask circuit outputs a signal of a "'0" pattern at the position detected by the inspection position detection circuit; A coloring circuit that converts the entire inside of the circular mask used in the same circuit into a "1" pattern, and a circular mask that is larger than the width of the pattern to be inspected is raster scanned in synchronization with the filled image, and the inside of the circle is scanned using a raster scan. includes an end detection circuit that detects the position of the "'1" pattern, and a hole defect determination circuit that does not determine a hole defect if a signal from the hole detection circuit is output at the detected end position. configured.

The pattern inspection device of the second invention reads out the image data of the pattern to be inspected using a photoelectric conversion scanner and reads it as 0゛, “1”.
a binary conversion circuit that converts the binary image into a binary image, a circular mask generation circuit that generates a circular inspection mask in synchronization with the binary image, and a raster scan of the circular mask with respect to the binary image. A comparison inspection circuit that scans synchronously and outputs a result as a defect if all the circumferential parts of the circular mask are "" + patterns and there is a +10 II pattern inside, and a comparison inspection circuit that outputs a result as a defect when the above defect is detected. all 1
``It is configured to include a coloring circuit that converts it into a pattern.

The pattern inspection device according to the third aspect of the invention reads an image of the pattern to be inspected using a photoelectric conversion scanner as "lQ". “
1' binary image; an inspection position detection circuit that detects the position of the "O" pattern in the binary image as an inspection position; and a preset size centered around the inspection position. a circular mask generating circuit that generates a circular mask; and a circular mask generating circuit that scans the circular mask in a raster scan manner in synchronization with the binary image so that two points facing each other on the circumference of the circular mask are "
The apparatus includes a pattern spacing inspection circuit that detects a spacing defect when the two points perpendicularly opposing two points of the "1" pattern are the "0" pattern.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

The image data a read out by the photoelectric conversion scanner 1 is 2
The value conversion circuit 2 converts it into a binary image of "0" and "1".

In synchronization with the binary image S, the circumferential mask circuit 3 outputs a circumferential detection mask having a preset size as a circumferential mask C.

Using the circumferential mask C, the inspection position detection circuit 4 raster scans the binary image, and when all the points on the circumference are in the "1" pattern, that position is set as the detection position d, Output.

On the other hand, the circular mask circuit 5 uses a circular mask C on the binary image.
If a circular mask of the same size is raster scanned and there is a "0" pattern inside the circular mask, +1
Q “Outputs a pattern signal.

“0 II When the position where the pattern signal is generated and the detection position d are the same point, the hole detection circuit 6 outputs the large defect position g.

On the other hand, at the detection position d, the filling circuit 7 converts the entire inside of a circular area having the same size as the circumferential mask C into a 1'' pattern, and outputs a filled-in image f.

The filled-in image f is raster-scanned by a circular mask larger than the pattern width in synchronization with the end detection circuit 8.

At that time, the position where the entire inside of the circular mask is the &+ “+ pattern is output as the end position.

In the hole defect determination circuit 9, when the signal of the large defect position g is received at the terminal position h←, it is not judged as defective and the signal of the large defect position g is detected.
If only, a defect signal i is output.

FIG. 2 is a diagram for explaining the operation of each circuit in FIG. 1.

In the inspection pattern 10, a circumferential mask "is scanned, and all points on the circumference of the mask are "1"' patterns, and inside the circular mask 12 is a "0" pattern (defect 1-IEi).
If there is, it is detected as a defect. At this time, the points inside the inner mask 12 at the detected positions are converted into a "1" pattern and the holes are filled in.

On the other hand, after filling in the hole, the circumference mask “larger,
Then, the end mask 13, which is larger than the pattern width, is scanned, and a black area in which the entire inside of the mask is a "'1" pattern is detected as the end position 14.

The defect 2-15 detected inside the end position 14 is a defect inside the pattern and is not considered a defect.

FIG. 3 is a block diagram showing a second embodiment of the invention.

The image signal aa read out by the photoelectric conversion scanner 1a is 2
It is converted into a binary image bb in the value conversion circuit 2a.

In synchronization with the binary image bb, the circular mask generation circuit 3a raster scans the circular inspection mask CC.

The inspection mask CC and the binary image bb are matched in the comparison inspection circuit 4a, and if the entire circumference of the inspection mask CC is a 1" pattern and there is a 0" pattern inside, a defect dd is output.

When a defective dd is output, in the filling circuit,
Convert all patterns in circular mask C to pattern 1,
Using the filled-in image ee as the binary image to be inspected for the next scan, inspection is performed in the same manner.

Next, referring to FIG. 4, the operation of the comparison test circuit 4 shown in FIG. 3 will be explained.

The inspection mask CC is scanned over the inspection pattern 10al, and if all the patterns on the circumferential mask lla are "'1", the mask is completely inside the pattern.

If a "01+ pattern (large defect) is detected at this position by the circular mask 12a inside the inspection mask CC, this position is output as the large defect 13a, and all images on the circular mask 12a are 1 “Convert to pattern.

Therefore, the large defect 13a at the same position will not be detected during the next raster scan.

FIG. 5 is a block diagram showing a third embodiment of the present invention.

The image data aaa read out by the photoelectric conversion scanner 1b is converted into a binary image bbb of "Q II, fl l" by the binarization circuit 2b.

The "0" pattern of the binary image b I)b is detected by the inspection position detection circuit 3b and outputted as the inspection position CCc.

The circular mask generation circuit 4b creates a circular inspection mask of a preset size centered on the inspection position CCC, and outputs it as a mask signal ddd.

The mask signal ddd is raster scanned in synchronization with the binary image in the pattern interval inspection circuit 5b. At this time, any two opposing points on the circumference of the mask each have a "'1" degree pattern, and the same circumference perpendicular to it.
If the two points are in the II OI+ pattern, a defect signal eee is output as a defective pattern spacing.

FIG. 6 is a diagram for explaining the operation of the pattern interval inspection circuit 5 in FIG. 5.

At the inspection position "b" between adjacent inspection patterns 10b, two opposing points of the circular mask 12b are in the "1" pattern, and two points perpendicular thereto are "0". This becomes a pattern, and this point can be detected as a pattern spacing defect.

Conversely, at the inspection position "c" where the pattern spacing is normal, there are no "O" patterns at two opposing points on the circumference of the circular mask 12c, and no defect is detected.

By varying the size of the circular mask or using a plurality of circular masks, it is possible to detect poor spacing of each size.

〔Effect of the invention〕

The pattern inspection device of the present invention has the following features: (1) Instead of extracting all large defects, it detects large defects at narrow positions of the pattern width and detects large defects at positions inside the wide pattern width according to the thickness (size) of the pattern. Since it has the function of not detecting defects, it has the effect of extracting only true defects, reducing the number of defective locations, and eliminating the need to reconfirm defects.

(2) A circular inspection mask is scanned over the pattern to detect holes in the pattern, and all holes in the inspection mask are filled in at the detected hole positions, so defects are detected according to the size of the large defect. This has the effect that the number of numbers does not change.

(3) Instead of detecting the pattern spacing in a limited direction, which was conventionally used, by scanning a circular inspection mask over the pattern to be inspected, inspection can be performed regardless of the inclination of the inspection pattern, allowing precision This has the advantage that no significant tilt correction is required.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
3 is a block diagram showing the second embodiment of the present invention. FIG. 4 is a diagram explaining the operation of each circuit in FIG. 3. FIG. 5 is a block diagram showing a third embodiment of the present invention, FIG. 6 is a diagram explaining the operation of each circuit in FIG. 5, and FIG. 7 is a schematic diagram showing a conventional example. 1... Photoelectric conversion scanner, 2... Binarization circuit, 3
...Circumferential mask circuit, 4...Inspection position detection circuit, 5
... Circle mask circuit, 6 ... Hole detection circuit, 7 ... Filling circuit, 8 ... Termination detection circuit, 7 ... Hole defect determination circuit, 10 ... Inspection pattern, "... Circumferential mask, 12... Circular mask, 13... End detection mask,
14... End position, 15... Defect 2.16... Defect 1.20... Large defect, a... Image data, b... Binary image, C... Circumferential mask , d...Detection position, e...Pa0''' pattern signal, f...Colored image, g...Large defect position, h
...Terminal position, i...Defect signal.

Claims (1)

[Claims] 1. A binarization circuit that converts an input image read out by scanning the pattern to be inspected with a photoelectric conversion scanner into a binary image of "0" and "1", and a circuit that is synchronized with the binary image. a circumferential mask circuit that generates a circular inspection mask; and a circumferential mask circuit that scans the binary image with the circumferential mask in a raster scan manner so that every point on the circumferential mask is located at an arbitrary position in the "1" pattern. An inspection position detection circuit that detects, a circular mask circuit that generates a circular mask on the binary image and detects whether a "0" pattern exists in the circular mask, and a position detected by the inspection position detection circuit. When a "0" pattern signal is output from the circular mask circuit, there is a hole detection circuit that outputs a signal as a hole position, and a hole detection circuit that outputs a signal as a hole position when the circular mask circuit outputs a signal, and a hole detection circuit that detects the entire inside of the circular mask used in the circuit at the position detected by the inspection position detection circuit. A filling circuit that converts the pattern into a 1" pattern, and an end detection device that raster scans a circular mask that is larger than the width of the pattern to be inspected in synchronization with the filled image, and detects the position where all the inside of the circle is a 1" pattern. A pattern inspection device comprising: a circuit; and a hole defect determination circuit that does not determine a hole defect if a signal from the hole detection circuit is output at the detected end position. 2. A binarization circuit that converts the image data read out from the pattern to be inspected by a photoelectric conversion scanner into a binary image of "0" and "1", and generates a circular inspection mask in synchronization with the binary image. a circular mask generating circuit that scans the binary image in synchronization with raster scanning, and the circular mask has a pattern of "1" all around the circumference and a pattern of "0" inside. A pattern inspection device comprising: a comparison inspection circuit that outputs a result as a defect if the defect is detected; and a filling circuit that converts the entire inside of the circular mask into a "1" pattern when the defect is detected. 3. A binarization circuit that converts the image of the pattern to be inspected read by a photoelectric conversion scanner into a binary image of "0" and "1", and detects the position of the "0" pattern in the binary image as the inspection position. an inspection position detection circuit that generates a circular mask of a predetermined size with the inspection position as the center; A pattern spacing inspection circuit that detects a spacing defect when two points facing each other on the circumference of the pattern are "1" patterns and two points facing at right angles to the two points are "0" patterns. pattern inspection equipment.