JPS6312311B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pattern inspection method for automatic pattern inspection.

Conventionally, the two-dimensional image shown in Fig. 1a is changed to Fig. 1b.
The distribution projected in the horizontal (X-axis) direction as shown in
As shown in FIG. 1c, there is a method of extracting pattern features from a distribution projected in the vertical (Y-axis) direction (hereinafter referred to as marginal distribution). However, the first
As shown in figure a, multiple patterns 10 are displayed on one screen.
1,102,103,104 exists, the first
As shown in Figures b and c, it is difficult to extract the features of individual patterns from the peripheral distribution.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a pattern inspection method that is capable of extracting features of individual patterns from peripheral distributions with a simple configuration.

That is, in order to achieve the above object, the present invention provides an imaging device that scans and images an object to be inspected in a two-dimensional direction in which a defect pattern occurs at an arbitrary position; a binarization circuit that converts the video signal obtained by the binarization circuit into a binary pixel; and a binary pixel conversion signal for each scanning line obtained from the binarization circuit, which scans the same X-ray pixel coordinate in the Y-axis direction. distribution forming means for forming a distribution of defect patterns in the X-axis direction by sequentially counting the number of pixels according to the number of pixels and storing the result in a storage means configured to store a predetermined number of bits for the total number of picture elements of one scanning line; , the level of the defective pattern of the binary pixel signal obtained from the binarization circuit is sequentially determined for each scanning line over one scanning line in the X-axis direction, and the signal that is present is determined. X-direction binary signal determination means to output;
Y-axis continuity determining means for determining an end scanning line where the existing signal from the direction binarized signal determining means is no longer detected from a state in which the existing signal is continuously detected for each scanning line; and the Y-axis continuity determining means. Each time the means determines that the scanning line is the end, the distribution of the defect pattern signal in the X-axis direction stored in the storage means of the distribution forming means is read out, and the storage means of the distribution forming means is cleared and read out. A separating means separates and outputs the defect pattern signal every time the distribution of the defect pattern signal is continuous in the X-axis direction, and a feature of the defect pattern is extracted for each distribution of the defect pattern signal separated and obtained by the separating means, and a standard is obtained. This is a pattern inspection method characterized by comprising a pattern determination means for determining a defective pattern by comparing the pattern with a value.

The overall configuration of a specific example of the present invention is shown in FIG. 2 below. In Fig. 2, 4 is an imaging device, 5 is a binarization circuit that binarizes the video signal from 4 and samples it with a clock pulse to convert it into picture elements, and 6 is a binary picture element signal. An X distribution creation circuit (feature distribution formation means) that creates a distribution in the X direction (hereinafter referred to as marginal distribution), 7 determines whether one level of the binary pixelated signal extends across the X axis direction. This is a Y-direction addition circuit that adds up the detected values if any. Reference numeral 8 denotes a coordinate generation circuit that generates coordinates in the scanning direction from the scanning clock of the imaging device obtained from 4, and 9 is a horizontal synchronization signal of 4.
10 is a Y-continuity determination circuit (Y-axis continuity determination means) that determines whether a pattern has occurred or disappeared in the Y-axis direction, and when the pattern ends in the Y-axis direction, 7 is set to the initial state, and at the same time, 6 is set to the initial state. The X distribution readout circuit 11 for reading out the X distribution is activated. Reference numeral 12 denotes a pattern judgment circuit (pattern judgment means) which calculates the characteristics of the pattern from the X distribution of 6 and judges each pattern.

FIG. 3 shows the specific configuration of the marginal distribution creation circuit. In Fig. 3, 13 is a memory in which the X distribution is created, and the memory capacity is the number of picture elements in the X direction of the imaging device, Xn bits (n: the number of scanning lines is sufficient).
14 is an address selection circuit which determines the write/read address for the memory 13 from the output of the coordinate generation circuit 8 which counts clock pulses based on the horizontal synchronizing signal, and 15 is an adder circuit. In this way, the memory No. 13 stores the value "0" of the binary signal 5 at the same address according to the coordinate position on the scanning line.
“1” is added. 16 is an X direction 2 that determines whether or not the binarized signal has become "1" on one scanning line based on the horizontal synchronization signal (Hsync).
This is a digitized signal determination circuit, and the output of 16 is added to the value of the memory 17 in the Y direction by the addition circuit 18 every time one scan is completed. 10 is a Y continuity judgment circuit that judges whether the value obtained in this way stops increasing, that is, a pattern exists in the Y-axis direction and then disappears, and every time the horizontal synchronization signal 9 is output. Make a judgment. When it is determined by 10 that the pattern is completed, the output of 10 clears the number of Y coordinates (number of scanning lines) stored in the memory 17, and further reads out the X distribution of 13. Reference numeral 11 denotes an X distribution reading circuit, which reads out the X distribution and at the same time clears the read memory 13. FIG. 4 shows a pattern determination circuit that determines the pattern based on the contents of the X distribution read out by 11;
The contents of each memory in the distribution.

Below, calculate the area of each pattern from 21,
FIG. 4 will be described with reference to pattern determination.
22 is an adder circuit which takes 21 as an input, sequentially adds and stores the contents of 21, and 21 becomes "0".
(that is, the projection of the pattern disappears in the X distribution), the gate circuit 23 outputs the contents of 22 to the area determination circuit 24, and at the same time, the contents of 22 are cleared. Note that the adder circuit 22 and the gate circuit 23 constitute separate storage means. The area determination circuit (comparison means) 24 compares the input contents 22 with a reference value and detects a pattern determination output 25. The operation of the present invention in the specific example described above will be explained using FIG. 1 as an example. In Figure 1, the pattern in the Y-axis direction ends at l ₁ , l ₂ ,
₁₃ , and is separated into patterns shown in FIG. 5a, FIG. 6a, and FIG. 7a.
The X distributions at l ₁ , l ₂ , and l ₃ are shown in Figures 5b, 6b, and 7c. In this way, Figures 5, 6, and 7
As is clear from the figure, according to the method of the present invention,
From each X distribution, the area of each pattern S ₁₀₁ , S ₁₀₂ , S ₁₀₃ ,
S ₁₀₄ can be easily determined.

Note that there are various forms of the imaging device 4 in the above embodiments. That is, an image pickup device captures a light image of a minute pixel area, and the pattern and the image pickup device scan relative to each other at a constant speed in two axial directions (X-axis, Y-axis) to obtain a two-dimensional video signal; In addition, a linear image sensor with a scanning function in one axis direction is used as an imaging device, and a two-dimensional image signal is obtained by scanning the pattern in the other axis direction, and a TV camera with a self-scanning function is used as an imaging device. There are some methods that obtain a two-dimensional video signal using the same method.

As explained above, according to the present invention, one distribution of the marginal distribution method conventionally used for pattern feature extraction is used to determine the end of a pattern, and the other distribution is referred to each time the pattern ends, and the pattern is This is used for feature extraction, and can extract the features of multiple defect patterns that exist in one screen with a simple configuration, which was a problem with the conventional marginal distribution method, almost for each pattern, and it follows the concept of fail-safe. This has the effect that pass/fail judgment can be made for each separated pattern.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a pattern on a two-dimensional plane and its peripheral distribution, FIGS. 2 to 4 are specific examples of the present invention, and FIGS. 5 to 7 are examples of the operation of the present invention. FIG. 2 is a schematic block diagram showing an embodiment of the pattern inspection method of the present invention, FIG. 3 is a block diagram specifically showing the X distribution creation circuit and Y direction addition circuit shown in FIG. 2, and FIG. In the block diagram specifically showing the pattern determination circuit shown in FIG. 2, each a in FIGS. 5 to 7 indicates a separated pattern, and each b in FIGS. 5 to 7 indicates its X distribution. FIG. Explanation of symbols, 4...Imaging device, 5...Binarization circuit, 6...X distribution creation circuit, 7...Y direction addition circuit, 10...Y continuity determination circuit, 11...X distribution readout circuit , 12... Pattern determination circuit.

Claims (1)

[Claims] 1. An imaging device that scans and images an object to be inspected where a defect pattern occurs at an arbitrary position in two-dimensional directions, and converts the image signal obtained by scanning in two-dimensional directions with the imaging device into binary picture elements. A binarization circuit and a binary pixel conversion signal obtained from the binarization circuit for each scanning line are sequentially counted as the same X-ray pixel coordinates are scanned in the Y-axis direction. distribution forming means for forming a distribution of the defect pattern in the X-axis direction by storing it in a storage means configured to store a predetermined number of bits for the total number of picture elements; and a binary picture obtained from the binarization circuit. X-direction binarized signal determining means for sequentially determining for each scanning line whether or not the level of the defect pattern of the pixelization signal exists over one scanning line in the X-axis direction, and outputting a signal that exists; Y-axis continuity determining means for determining an end scanning line where the existing signal from the X-direction binarized signal determining means is no longer detected from a state in which the existing signal is continuously detected for each scanning line; Each time the scanning line is determined to be an end scanning line by the gender determination means, the distribution of defect pattern signals in the X-axis direction stored in the storage means of the distribution formation means is read out, and the storage means of the distribution formation means is cleared and read out. a separating means for separating and outputting the defect pattern signal distribution each time the defect pattern signal distribution is continuous in the X-axis direction; 1. A pattern inspection method, comprising: pattern determination means for determining a defective pattern by comparing it with a reference value.