JPH0528271A - Optimum part pattern extraction device - Google Patents

Abstract

PURPOSE:To reduce an operation amount in pattern matching even if the number of the picture elements of reference picture data increases to shorten operation time. CONSTITUTION:A reference picture extraction means 11 which changes a coordinate and sequentially fetches reference part data on the prescribed number of the picture elements from reference picture data, a matching detection means 12 obtaining respective matching degrees when reference part data fetched by the reference picture extraction means is shifted by the prescribed number of the picture elements in respective directions with respect to reference picture data, an optimum data adoption means 13 adopting reference part data on the coordinate showing the optimum matching degree from detected respective matching degrees with respect to respective reference part data different in the coordinate are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optimum partial pattern extracting apparatus for extracting reference partial data from reference image data in order to detect a positional deviation of input image data with respect to reference image data.

[0002]

2. Description of the Related Art In semiconductor manufacturing, masks and wafers used are inspected for defects. In this defect inspection, for example, the reference image data of the mask and the input image data obtained by imaging the mask with a CCD camera or the like are aligned, and then the reference image data and the input image data are compared to detect a defect. There is.

By the way, there are a method of using a specific mark and a method of using a pattern matching method for aligning the reference image data and the input image data. FIG. 8 is a block diagram of an image data extraction device that obtains image data aligned by using the pattern matching method. The reference image memory 1 stores reference image data of various mask patterns of m × n pixels, for example, 1000 × 1000 pixels. on the other hand,
A two-dimensional array sensor 3 is connected to the input image memory 2, and an image signal of a mask imaged by the two-dimensional array sensor 3 is input and stored as input image data of (m + 2k) (n + 2l) pixels. .. The input image data is (m + 2k) (n + 2l) pixels slightly larger than the reference image data of m × n pixels, where k, l
Indicates a large number of pixels in the vertical and horizontal directions. The reference image memory 1 and the input image memory 2 are connected to the pattern matching circuit 4, the reference image data is taken out from the reference image memory 1 and sent to the pattern matching circuit 4, and the input partial data is taken out from the input image memory 2. Are sent to the pattern matching circuit 4.

The pattern matching circuit 4 matches the reference partial data with the input partial data by (2k + 1).
(2l + 1) times to find each matching degree,
These matching degrees are sent to the peak detection circuit 5. In addition,
The matching degree is “1” when the same patterns are used by the same person. The peak detection circuit 5 compares the matching degrees to detect the maximum matching degree and obtains the coordinates indicating the matching degree. Then, the coordinates are stored in the optimum data memory 6 as alignment data between the reference image data and the input image data. After that, the reference image data and the input image data are aligned with each other at this coordinate and a defect inspection is performed.

By the way, the reference image data of the mask may have a size exceeding 1000.times.1000 pixels as described above. In this case, the pattern matching circuit 4 needs to be enlarged in accordance with the number of pixels of the reference image data. There is. When the scale is increased in this way, the amount of calculation in the pattern matching circuit 4 increases and the calculation time increases.

[0006]

As described above, when the size of the reference image data becomes very large, the amount of calculation in the pattern matching circuit 4 increases and the calculation time becomes long.

Therefore, it is an object of the present invention to provide an optimum partial pattern extraction device which can reduce the amount of calculation in pattern matching and shorten the calculation time even if the number of pixels of reference image data increases.

[0008]

SUMMARY OF THE INVENTION According to the present invention, reference image extracting means for sequentially extracting reference image data of a predetermined number of pixels from reference image data while changing coordinates, and reference image data extracted by the reference image extracting means. Matching detection means for obtaining each matching degree when a predetermined number of pixels are shifted in each direction with respect to the reference image data, and a predetermined matching degree among the matching degrees obtained by this matching detection means is detected, and An optimum partial pattern extracting device for achieving the above object, which comprises an optimum data adopting means for adopting reference partial data of coordinates showing an optimum matching degree from each matching degree detected for each different reference partial data. is there.

[0009]

With the provision of such means, the reference image data of the predetermined number of pixels from the reference image data are sequentially extracted by changing the coordinates. Then, the matching detection means obtains the highest matching degree among the matching degrees when the reference partial data is shifted by a predetermined number of pixels in each direction with respect to the reference image data, and then the optimum data adopting means determines the matching degree. The predetermined matching degree is detected, and the reference portion data of the coordinate showing the optimum matching degree is adopted from the respective matching degrees detected for the respective reference portion data having different coordinates.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 8 are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 1 is a block diagram of a position detecting device to which an optimum partial pattern extracting device is applied. A reference partial image data extraction circuit 10 is connected to the reference image memory 1. The reference partial image data extraction circuit 10 operates according to the reference partial data extraction flow chart shown in FIG. 2, and has the functions of a reference image extraction unit 11, a matching detection unit 12, and an optimum data adoption unit 13.

The reference image extraction unit 11 changes the coordinates of the reference partial data of a predetermined number of pixels s × p from the reference image data of m × n pixels stored in the reference image memory 1 over the entire reference image data. It has a function to take out sequentially. Note that the numbers of pixels s and p have a relationship of s, p <m, n.

The matching detection circuit 12 also obtains the matching degrees A11, A12 ... A33 when the reference partial data sequentially fetched by the reference image extraction unit 11 is shifted by one pixel in each of eight directions with respect to the reference image data. It has the required function. The numerical values 11, 12, ... 33 attached to A indicate coordinates in the reference part data.

The optimum data adopting section 13 also determines the matching degrees A11 and A12 obtained by the matching detecting circuit 12.
... The highest matching degree maxAq (q = 1, 2 of A33)
...), and the maximum matching degrees maxA1 and maxA2 obtained for the reference partial data with different coordinates
, MaxA3 ... And has a function of adopting the reference part data of the coordinates showing the minimum matching degree.

On the other hand, an input image extraction circuit 14 is connected to the input image memory 2. This input image extraction circuit 14
Is the number of pixels whose coordinates correspond to the reference partial data adopted by the reference partial image data extraction circuit 10 from the input image data stored in the input image memory 2 and which is larger than the reference partial data by a predetermined number of pixels 2k, 2l. (S + 2
It has a function of extracting k) × (p + 2l) input partial data.

The pattern matching circuit 15 is s × p.
The pattern matching between the reference partial data of the pixel and the input partial data of the (s + 2k) × (p + 2l) pixel is performed by (2k +
1) × (2l + 1) times to obtain the matching degree. Next, the operation of the device configured as described above will be described.

Reference image data of 6 × 6 pixels shown in FIG. 3 is stored in the reference image memory 1. In step s1, the reference image extraction unit 11 changes the coordinates of the reference image data stored in the reference image memory 1 by a predetermined number of pixels s × p, for example, 3 × 3 pixels, and changes the coordinates to cover the entire reference image data. Take out sequentially. 4 and 5 are examples of the respective reference partial data, and the reference partial data F
It is a schematic diagram of 1 and F2.

Next, in step s2, the matching detection circuit 12 obtains matching degrees A11, A12, ... A33 when the reference partial data F1, F2, ... Are shifted by one pixel in each of eight directions with respect to the reference image data. .. That is, since the reference partial data F1 corresponds to the coordinates (3, 3) in the reference image data, the matching detection circuit 12 shifts the reference partial data F1 from the coordinates (3, 3) by one pixel in each of the eight directions to the coordinates (2, 3). 2), (2,3),
(2, 4), (3, 2), ... (4, 4), respectively, and the degree of matching with the reference image data is obtained at these coordinate positions. As shown in FIG. 6, the matching degree is "6/9" at the coordinates (2, 2) and "8/9" at the coordinates (3, 4), for example. Note that, for example, the matching degree “6/9” indicates that 6 out of 9 pixels match. In addition, the matching detection circuit 12 outputs, for example, the reference partial data F2 from the coordinates (3, 4) pixel by pixel 8
Then, the degree of matching with the reference image data is obtained at these coordinate positions. This matching degree is, for example, as shown in FIG. 7, coordinates (2, 3) of the reference partial data F2.
Is "5/9", and the coordinates (3, 3) are "8/9".

Next, in step s3, the optimum data adopting section 13 detects the highest matching degree among the matching degrees obtained by the matching detecting section 12. For example, the optimum data adoption unit 13 detects the matching degree “8/9” with respect to the reference partial data F1 and also detects the matching degree “8/9” with respect to the reference partial data F2.

Next, in step s4, it is judged whether the reference partial data F1, F2, ... Are fetched over the entire reference image data. By this judgment, the reference partial data F1, F2 over the entire reference image data. , ... Are taken out, the process proceeds to the next step s6.

In this step s6, the optimum data adopting section 13 detects the minimum matching degree among the maximum matching degrees obtained for the reference partial data of each coordinate, and the coordinate reference showing the minimum matching degree. The partial data is adopted and sent to the pattern matching circuit 15.

On the other hand, in the input image extraction circuit 14, the input image data stored in the input image memory 2 has a coordinate corresponding to the reference partial data adopted by the optimum data adopting unit 13, and is more predetermined than the reference partial data. 2k pixels
The pattern matching circuit 15 extracts the input partial data of the number of pixels (s + 2k) × (p + 2l) larger by 2l.
Send to.

The pattern matching circuit 15 matches the reference partial data with the input partial data by (2k +
1) It performs (2l + 1) times to find each matching degree, and sends these matching degrees to the peak detection circuit 5. The peak detection circuit 5 compares the matching degrees to detect the maximum matching degree and obtains the coordinates indicating the matching degree. Then, the coordinates are stored in the optimum data memory 6 as alignment data between the reference image data and the input image data. After that, the reference image data and the input image data are aligned with each other at this coordinate and a defect inspection is performed.

As described above, in the above-described embodiment, the reference partial data having the number of pixels of 3 × 3 are sequentially taken out from the reference image data while changing the coordinates, and these reference partial data are set to 1 in 8 directions with respect to the reference image data. Obtaining each matching degree when shifting by the number of pixels, then detecting the highest matching degree among these matching degrees, and showing the lowest matching degree among the highest matching degrees for each reference partial data with different coordinates. Since the reference part data of the coordinates is adopted, the adopted reference part data is the part in which the most characteristic pattern is drawn in the reference image data, and the reference part data is used to input the reference image data. If the image data is positioned, the amount of matching calculation in the pattern matching circuit 15 can be reduced and the processing time can be shortened. .

The present invention is not limited to the above-mentioned embodiment, and may be modified within the scope of the invention. For example, the reference partial data is not limited to s × p pixels, and 1
Pixels may be extracted and formed for each pixel. Further, the reference image data in which the suboptimal pattern is drawn may be stored, and the suboptimal reference image data may be used when the matching with the best reference image data is not preferable. Thereby, the reliability of pattern matching can be improved. On the other hand, the optimum data adopting unit 13 detects the maximum matching degree in some specific directions out of the eight matching directions obtained by the matching detecting unit 12 in each of the eight directions, and each reference having different coordinates. It may be a function of adopting the reference partial data of the coordinates showing the minimum matching degree from the maximum matching degree detected for the partial data. Furthermore, the pattern matching circuit 15 may perform pattern matching using two reference partial data.

[0026]

As described above in detail, according to the present invention, there is provided an optimum partial pattern extraction device capable of reducing the calculation amount in pattern matching and shortening the calculation time even if the number of pixels of the reference image data increases. Can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a positioning device to which an embodiment of an optimum partial pattern extracting device according to the present invention is applied.

FIG. 2 is a flowchart for extracting reference partial data of the apparatus.

FIG. 3 is a schematic diagram of reference image data in the same device.

FIG. 4 is a schematic diagram of input partial data in the same device.

FIG. 5 is a schematic diagram of input partial data in the same device.

FIG. 6 is a diagram showing a matching degree in the same apparatus.

FIG. 7 is a diagram showing a matching degree in the device.

FIG. 8 is a block diagram of a conventional device.

[Explanation of symbols]

1 ... Reference image memory, 2 ... Input image memory, 5 ... Peak detection circuit, 6 ... Optimal data memory, 10 ... Reference partial image data extraction circuit, 11 ... Reference image extraction unit, 12 ... Matching detection unit, 13 ... Optimal data Adopting unit, 14 ... Input image extracting circuit, 15 ... Pattern matching circuit.

Claims (1)

Claim: What is claimed is: 1. A reference image extracting unit for sequentially extracting reference partial data of a predetermined number of pixels from the reference image data while changing coordinates, and the reference partial data extracted by the reference image extracting unit. Matching detection means for obtaining each matching degree when shifted by a predetermined number of pixels in each direction with respect to the reference image data, and detecting a predetermined matching degree out of each matching degree obtained by this matching detection means,
And an optimum data adopting means for adopting the reference part data of the coordinates showing the optimum matching degree from the respective matching degrees detected for the respective reference part data of different coordinates. ..