TWI674048B - Displacement amount acquisition apparatus, inspection apparatus, displacement amount acquisition method, and inspection method - Google Patents

Abstract

An image division unit (411) of the position shift amount acquiring device (41) divides one of the two images to obtain a divided region group. The adaptive region specifying unit (412) obtains the suitability of the offset amount acquisition processing for each divided region with respect to the positional offset amount between the two images, thereby identifying the appropriate offset acquisition process from the divided region group. A plurality of regions of fitness. A position shift amount acquisition unit (413) performs a shift amount acquisition process between two images in each adaptive region, thereby obtaining a position shift amount of the adaptive region. The position offset calculation unit (414), based on the position offsets of the plurality of adaptive regions and the positional relationship between the plurality of adaptive regions, for the unsuitable regions in the divided region group that are not included in the plurality of adaptive regions. To find the position offset. Thereby, the positional shift amount of each divided area in the two images can be accurately obtained.

Description

   Position deviation amount acquisition device, inspection device, position deviation amount acquisition method, and inspection method   

The present invention relates to a position shift amount acquisition device, an inspection device, a position shift amount acquisition method, and an inspection method.

It is known that the visual inspection of printed substrates will use design information such as CAM (Computer Aided Manufacturing) data as a benchmark for inspection. For example, the image of the design pattern shown in the design data is compared with the image of the wiring pattern on the printed circuit board, and the difference that is more than a certain degree is extracted as a defect. In such a comparison check, alignment of two images is performed. In this alignment, the amount of positional shift between the two images is obtained.

Furthermore, Japanese Patent Laid-Open No. 6-300703 discloses an inspection device that compares each evaluation segment formed by dividing an inspected image and a reference image into regions of a predetermined size, For defect detection. In this inspection device, the position shift amount of the two images in each evaluation segment is obtained to obtain the frequency distribution with respect to the position shift amount. The position of the center of gravity of the frequency distribution is obtained as the positional offset of the entire image, and the distance between the point farthest from the center of gravity and the center of gravity is obtained as the maximum value of the internal strain in the pattern shown in the inspected image.

However, in a case where two images are aligned for each divided area of a predetermined size, there is a case where a pattern of one divided area is composed of, for example, a linear pattern element extending in one direction only. In this case, although the position shift amount in the direction perpendicular to the one direction can be obtained with good accuracy, it is difficult to obtain the position shift amount in the one direction with high accuracy.

The present invention is used for a position shift amount acquiring device, and the object thereof is to accurately calculate the position shift amount of each divided region in two images.

The position shift amount obtaining device according to the present invention includes an image division unit that divides one of two images to obtain a divided region group, and an adaptive region specifying unit that obtains each divided region with respect to obtaining the above-mentioned 2 The positional amount of the positional offset amount between the images is obtained as the suitability of the process, thereby identifying a plurality of adaptive regions suitable for the above-mentioned offset amount acquisition process from the segmented area group; Performing the above-mentioned offset amount acquisition processing between the two images in each of the adaptive regions, thereby obtaining the positional offset amount of the respective adaptive regions; and a positional offset amount calculating unit, which The discomfort regions included in the plurality of adaptive regions are obtained based on the positional shift amounts of the plurality of adaptive regions and the positional relationship between the discomfort regions and the plurality of adaptive regions.

According to the present invention, the position shift amount of each divided region in the two images can be accurately obtained.

In a preferred aspect of the present invention, the adaptability region specifying unit determines the adaptability by detecting feature points included in the pattern shown in each of the divided regions.

In another preferred form of the present invention, the above-mentioned one image is an image derived from design data showing a design pattern, and the other of the two images is formed by shooting based on the above-mentioned design data. The image obtained by the object of the actual pattern.

In one aspect of the present invention, in the offset obtaining process, while moving the adaptive regions of the one image up, down, left, and right, and obtaining the other of the adaptive regions and the two images The difference in the image is used to obtain the above-mentioned position shift amount of each of the adaptive regions.

In another aspect of the present invention, a calculation formula is set in advance that uses the position of each of the divided regions as a parameter, and the position shift amount calculation unit is based on the position shift amounts of the plurality of adaptive regions and the above. The position of the plurality of adaptive regions is used to find the coefficient of the above formula.

The invention is also used in inspection devices. The inspection device of the present invention includes the aforementioned position shift amount acquisition device and an inspection unit that performs the above two while using the position shift amount of each of the divided regions obtained by the position shift amount acquisition device. The alignment of the images, while obtaining the inspection results of the inspected images included in the two images.

The present invention is also applied to a method for obtaining a position offset amount and a method for inspection.

The foregoing objects and other objects, features, aspects, and advantages can be made clear by referring to the accompanying drawings and performing the detailed description of the present invention below.

1‧‧‧ pattern inspection device

2‧‧‧device body

3‧‧‧ computer

6‧‧‧Reference image

8‧‧‧ recording media

9‧‧‧ substrate

21‧‧‧Photographic installation

22‧‧‧ Platform

23‧‧‧Platform driver

31‧‧‧CPU

32‧‧‧ROM

33‧‧‧RAM

34‧‧‧ fixed disk

35‧‧‧ Display

36a‧‧‧Keyboard

36b‧‧‧mouse

37‧‧‧Reading device

38‧‧‧ Ministry of Communications

41‧‧‧Position shift obtaining device

42‧‧‧ Inspection Department

48‧‧‧Design Information

49‧‧‧Storage Department

50‧‧‧ Checked divided area

51‧‧‧ pixels

51a‧‧‧ center pixel

52‧‧‧ Center of Gravity

60‧‧‧ divided area

61‧‧‧Pattern area

62‧‧‧ background area

63‧‧‧ pattern recess

64‧‧‧ pattern convex

71, 71a, 71b, 71c‧‧‧ arrows

72, 72A‧‧‧ pixels

80‧‧‧program

81, 81a‧‧‧arrow

82‧‧‧ pixels

211‧‧‧Lighting Department

212‧‧‧optical system

213‧‧‧Photography Department

411‧‧‧Image segmentation section

412‧‧‧Suitable area specific department

413‧‧‧Position offset acquisition unit

414‧‧‧Position shift calculation unit

510‧‧‧Pixel arrangement

S10 ~ S18‧‧‧step

FIG. 1 is a diagram showing the configuration of a pattern inspection device.

Fig. 2 is a diagram showing the structure of a computer.

FIG. 3 is a block diagram showing a functional configuration of the pattern inspection device.

FIG. 4 is a diagram showing a processing flow for inspecting a substrate.

FIG. 5 is a diagram showing a divided region group.

FIG. 6 is a diagram showing a part of the divided area.

FIG. 7 is a diagram showing a part of the divided area.

FIG. 8 is a diagram showing an adaptive region.

FIG. 9 is a diagram showing an uncomfortable area.

FIG. 10 is a diagram showing a plurality of adaptive regions in a segmented region group.

FIG. 11 is a diagram for explaining offset obtaining processing.

FIG. 12 is a diagram showing a pixel arrangement of the divided region under inspection.

FIG. 13 is a diagram showing a pixel arrangement of the inspected divided area corresponding to the uncomfortable area.

FIG. 1 is a diagram showing a configuration of a pattern inspection apparatus 1 according to an embodiment of the present invention. The pattern inspection apparatus 1 is, for example, an apparatus for inspecting the appearance of a printed circuit board (also referred to as a printed wiring board) before electronic components are mounted.

Here, the printed circuit board is formed by forming a wiring pattern on the surface of a resin substrate 9 (hereinafter referred to simply as "substrate 9") with a conductive material such as copper. In the manufacture of a printed circuit board, a film (conductive film) of a conductive material is provided on the surface of the substrate 9. A photoresist film as a photosensitive material is formed on the conductive film, and an image of a pattern based on design data is directly drawn on the photoresist film by a drawing device (direct patterning device). The patterned substrate 9 is subjected to a development process, an etching process, a photoresist peeling process, and the like. As a result, a wiring pattern is formed on the substrate 9. The etching process for the substrate 9 is, for example, wet etching by applying an etchant to the substrate 9. As the etching process for the substrate 9, dry etching using a plasma or the like may be performed, for example. In addition, a mask for displaying a design pattern may be used to form (expose) the pattern on the photoresist film.

The pattern inspection device 1 is provided with a device body 2 that images the substrate 9 and a computer 3 that controls the overall operation of the pattern inspection device 1 and realizes a calculation unit and the like described later. The device body 2 includes a photographing device 21 that captures a multi-gradation photographic image (data) of the substrate 9, a platform 22 that holds the substrate 9, and a platform that relatively moves the platform 22 relative to the photographing device 21. Driving section 23. The photographing device 21 includes an illumination section 211 that emits illumination light, an optical system 212 that guides the illumination light to the substrate 9 and allows light from the substrate 9 to enter, and converts an image of the substrate 9 imaged by the optical system 212 into Electrical signal of the photography department 213. The platform driving unit 23 is composed of a ball screw, a guide rail, a motor, and the like. The computer 3 controls the platform driving unit 23 and the photographing device 21 to photograph a predetermined area on the substrate 9.

FIG. 2 is a diagram showing the configuration of the computer 3. The computer 3 includes a CPU (Central Processing Unit) 31 for performing various arithmetic processing, a ROM (Read-Only Memory) 32 for storing basic programs, and a RAM (Random Access Memory) for storing various information. Access memory) 33 is a general computer system. The computer 3 further includes a fixed disk 34 for storing information, a display 35 for displaying various information such as images, a keyboard 36a and a mouse 36b that accept input from an operator, a self-optical disk, a magnetic disk, and an optical magnetic disk. A reading device 37 that reads information from a computer-readable recording medium 8 and a communication unit 38 that transmits and receives signals to and from other components of the pattern inspection device 1.

In the computer 3, the program 80 is read from the recording medium 8 via the reading device 37 in advance and stored in the fixed disk 34. The CPU 31 executes arithmetic processing while using the RAM 33 and the fixed magnetic disk 34 in accordance with the program 80.

FIG. 3 is a block diagram showing the functional configuration of the pattern inspection device 1. In FIG. 3, a dashed rectangle with a symbol 3 surrounds the CPU 31, ROM 32, RAM 33, fixed disk 34, and the like implemented by the computer 3. Functional composition. The computer 3 includes a position shift amount acquiring device 41, an inspection unit 42, and a storage unit 49. The position shift amount acquisition device 41 includes an image division section 411, an adaptive region specifying section 412, a position shift amount acquisition section 413, and a position shift amount calculation section 414. The storage unit 49 stores design data 48 such as CAM data (or CAD (Computer Aided Design) data). The details of the functions performed by these constituents are described later. Furthermore, these functions can be constructed by dedicated circuits, or they can be partially utilized.

FIG. 4 is a diagram showing a processing flow for inspecting the substrate 9 by the pattern inspection device 1. Here, a plurality of substrates 9 manufactured as one batch (hereinafter referred to as "target batch") are set as inspection targets. The plurality of substrates 9 included in the target lot are used for the manufacture of the same product, and the same wiring pattern is formed.

In the pattern inspection device 1, first, the design data 48 used when forming the wiring pattern on the surface of the substrate 9 (hereinafter, the wiring pattern on the substrate 9 is actually referred to as the "actual pattern") is input to the storage. The unit 49 prepares (step S10). The design data 48 of this embodiment is vector data showing a design pattern. The design data 48 may also be Raster data. The actual patterns on the plurality of substrates 9 included in the target lot are formed by an etching process or the like according to the design data 48.

The image division unit 411 generates a binary image (hereinafter referred to as a "reference image") in which a design pattern is displayed. In the reference image, a plurality of pixels are arranged along the column direction and the row direction, and a value (for example, 1) is assigned to each pixel included in the pattern region of the design pattern, and each pixel included in the background region is assigned Another value (for example, 0). As shown in FIG. 5, the reference image 6 is divided into a plurality of regions 60 (hereinafter referred to as "divided regions 60") (step S11). For example, the reference image 6 is equally divided in the column direction and the row direction, and the plurality of divided regions 60 are the same size. The plurality of divided regions 60 may also have different sizes. In the following description, a set of a plurality of divided regions 60 is referred to as a "divided region group".

6 and 7 are diagrams showing a part of the divided area 60. When the segmented area group is obtained by the image segmentation unit 411, the adaptive region specification unit 412 uses the pixels in the reference image 6 that are not included in the pattern region 61, that is, the pixels included in the background region 62 as the target pixels, respectively. The distance from the target pixel to the edge of the pattern area 61 is measured in eight directions set at 45-degree intervals (hereinafter referred to as "background measurement distance"). In FIG. 6, the background measurement distance in eight directions when the pixel 82 is used as the target pixel is indicated by an arrow 81 (the symbol 81 a is indicated by one arrow).

Among the target pixels, when the background measurement distance in only one direction is greater than a predetermined determination distance and the background measurement distance in the other 7 directions is less than the determination distance, the target pixel is detected as a recessed pixel. In the pixel 82 in FIG. 6, since only the background measurement distance shown by the arrow 81 a is equal to or greater than the determination distance, the pixel 82 is a recessed pixel. The recessed pixel indicates the presence of a recessed portion 63 (hereinafter referred to as "patterned recessed portion 63") of the pattern region 61. The upper limit of the background measurement distance is set in advance, and the arrow 81a in FIG. 6 becomes the upper limit of the background measurement distance. The exploration of the recessed pixels can also be performed for each predetermined number of pixels in the background area 62 (the same applies to the exploration of the protruding pixels).

The adaptive region specifying unit 412 further uses each pixel included in the pattern region 61 as a target pixel, and measures the distance from the target pixel to the edge of the pattern region 61 in each of eight directions set at 45-degree intervals (hereinafter referred to as "Pattern measurement distance"). In FIG. 7, the pattern measurement distances in the eight directions when the pixels 72 and 72A are used as the target pixels are indicated by arrows 71 (the three arrows are denoted by the symbols 71 a, 71 b, and 71 c).

Then, when the pattern measurement distance in only one direction is greater than the predetermined determination distance and the pattern measurement distance in the other 7 directions is less than the determination distance, the target pixel is detected as a convex pixel. Out. The pixel 72 in FIG. 7 is a projection pixel only because the distance measured by the pattern shown by the arrow 71 a is equal to or more than the determination distance. In FIG. 7, the pixel at the front of the solder joint is shown as a convex pixel. In addition, the pixel 72A is not a convex pixel because the measurement distance of the two patterns shown by arrows 71b and 71c is equal to or greater than the determination distance. The convex portion pixel indicates the existence of a convex portion 64 (hereinafter referred to as "pattern convex portion 64") of the pattern region 61. The upper limit of the pattern measurement distance is set in advance, and the arrows 71 a and 71 b in FIG. 7 become the upper limit of the pattern measurement distance.

The adaptive region specifying unit 412 obtains the number of convex pixels and concave pixels included in each divided region 60. The divided region 60 having a predetermined number or more is specified as an adaptive region (step S12). In FIG. 8, three divided regions 60 that are specified as adaptive regions are arranged vertically and displayed. On the other hand, the divided areas 60 in which the number of the convex pixels and the concave pixels are less than a predetermined number are specified as uncomfortable areas. In FIG. 9, three divided regions 60 that are specified as uncomfortable regions are arranged vertically and displayed. In FIG. 10, a parallel oblique line is assigned to a divided region 60 that is specified as a suitable region in the divided region group of the reference image 6.

As described later, in the inspection of the substrate 9, the alignment between the photographed image of the substrate 9 and the reference image 6 is performed. In this alignment, the amount of positional deviation between the pattern shown in each divided region 60 of the reference image 6 and the pattern in the photographic image that coincides with (or substantially coincides with) the pattern is obtained. In order to obtain the positional shift amount accurately for each of the divided regions 60, it is preferable that the pattern shown in the divided region 60 includes the pattern recessed portion 63 and the pattern raised portion 64 to some extent (the reason will be described later). Therefore, in the adaptive region specifying unit 412, the divided region 60 in which the number of the concave pixels and the convex pixels in the divided region group is equal to or greater than a predetermined number is used as a process suitable for obtaining the position shift amount (position shift amount acquiring unit The processing performed by 413 is hereinafter referred to as the "offset acquisition processing"). In other words, the divided regions 60 in which the number of the concave pixels and the convex pixels in the divided region group are less than a predetermined number are used as unsuitable regions that are not suitable for the offset obtaining process. The uncomfortable area is a divided area 60 that is not included in the plurality of adaptive areas in the divided area group.

Next, in the device body 2, the first substrate 9 included in the plurality of substrates 9 in the target lot is placed on the stage 22 (see FIG. 1). A predetermined area on the substrate 9 is provided by the stage driving unit 23. It is arranged in a photographing area of the photographing section 213. Then, a photographed image (hereinafter referred to as an “actual pattern image”) showing an actual pattern is acquired by the imaging unit 213, and is output to the position shift amount acquisition device 41 (step S13). In the actual pattern image, as in the reference image 6, a plurality of pixels are arranged along the column direction and the row direction. The resolution of the actual pattern image is the same as that of the reference image 6. In other words, the reference image 6 is generated from the design data 48 in accordance with the resolution of the photographed image of the photographing section 213. The size of the area on the substrate 9 shown by one pixel of the reference image 6 is the same as the size of the area on the substrate 9 shown by one pixel of the actual pattern image.

In the position shift amount obtaining unit 413, the actual pattern image is valued by a predetermined threshold value, and a binary image (hereinafter referred to as a "checked image") displaying the actual pattern is generated. Then, an offset amount acquisition process between the inspected image and the reference image 6 is performed in each of the divided regions 60 that are adaptive regions, and a positional offset amount is acquired for each adaptive region (step S14).

FIG. 11 is a diagram for explaining offset obtaining processing. In FIG. 11, it is shown that the divided region 60 (shown by a solid rectangle with parallel oblique lines) is shifted up, down, left, and right with respect to the inspected divided region 50 (shown by a dashed rectangle) described later. In this processing example, similarly to the divided region group of the reference image 6, the image to be inspected is divided along the column direction and the row direction, and among the images to be inspected, the image corresponding to the reference image 6 is specified. An area 50 of each divided area 60 (an area showing a position on the same substrate 9 as the divided area 60, hereinafter referred to as a "inspected divided area 50"). In the offset obtaining process, as shown in the center in FIG. 11, the entire area of the divided area 60 is superimposed on the entire area of the inspected divided area 50 corresponding to the divided area 60, and the number of the divided areas 60 is obtained. The difference (absolute value) between the value of each pixel and the value of a pixel of the inspected image overlapping the pixel. Then, the sum of the difference values obtained with respect to the pixels of the entire divided area 60 is obtained as an evaluation value.

In addition, the evaluation value was obtained in the same way while moving the divided area 60 from the position of the inspected divided area 50 one pixel at a time up and down (column direction and row direction). In this way, the divided regions 60 are arranged on the side such that the pixels in the pixel array of M columns and N rows (M and N are arbitrary integers) in the center of the inspected divided region 50 are set to overlap the central pixels of the divided region 60. Get the evaluation value. Then, among the plurality of pixels in which the center pixel of the divided region 60 is superimposed in the inspected divided region 50, a pixel that has obtained an evaluation value below a predetermined threshold value is specified as a specific pixel. In a state where the central pixel of the divided area 60 overlaps a specific pixel, the difference between the divided area 60 and the inspected image is relatively small.

FIG. 12 is a diagram showing an arrangement 510 (ie, pixel arrangement 510) of the pixels 51 of 5 columns and 5 rows in the center with the central pixel 51a of the inspected divided area 50 as the center, and parallel oblique lines are marked for specific pixels 51. In the offset amount acquisition processing of the divided region 60 as the adaptive region, the plurality of specific pixels 51 are grouped together as a specific pixel group. Then, as a position shift amount of the divided region 60, a vector from the center pixel 51a of the inspected divided region 50 toward the center of gravity position 52 of the specific pixel group is obtained. The position shift amount includes a component in a row direction and a component in a row direction. In the following description, these components are referred to as a “position shift amount in a column direction” and a “position shift amount in a row direction”. As described above, in the position shift amount obtaining unit 413, while moving each of the adaptive regions of the reference image 6 up, down, left, and right, the difference between the adaptive region and the inspected image is obtained, thereby obtaining the adaptive region. Position offset.

Furthermore, even if the divided area 60 cannot be obtained even if any of the pixels 51 of the pixel array 510 of M columns and N rows is arranged in the divided region 60 (the specific pixel 51 cannot be obtained), the pixel array 510 The adjacent new pixel array is subjected to the same processing as described above. In the offset acquisition processing, the above-mentioned processing is repeated until a specific pixel 51 is acquired or until a predetermined number of new pixel arrays are set. When a specific pixel 51 cannot be obtained even if a predetermined number of new pixel arrangements are set, the above-mentioned processing is stopped and repeated, for example, the segmented region 60 is changed from an adaptive region to an uncomfortable region.

In the pattern inspection apparatus 1, a calculation formula (hereinafter referred to as a “shift amount calculation formula”) of the position shift amount using the position of each divided region 60 as a parameter is set in advance. For example, in the offset calculation formula of Formula 1, the position Xb in the column direction and the position Yb in the row direction of the center pixel of the divided region 60 shown in FIG. 10 are used to indicate the position offset ΔX and Position shift amount ΔY in the row direction. In Equation 1, αx, βx, γx, αy, βy, and γy are coefficients.

[Equation 1] △ X = αx‧Xb + βx‧Yb + γx △ Y = αy‧Xb + βy‧Yb + γy

In the position shift amount calculation unit 414, based on the positions of the plurality of suitability regions (the positions of the divided regions 60 with parallel oblique lines in FIG. 10) and the plurality of suitability obtained by the position shift amount acquisition unit 413, The positional shift amount of the area is used to obtain the coefficients αx, βx, γx, αy, βy, and γy (values) of the shift amount calculation formula (step S15). For example, these coefficients are obtained by the least square method. In the least square method in Equation 2 derived from Equation 1, the position of the central pixel in the column direction Xb and the row direction position Yb in the plurality of adaptive regions, and the position offset △ X in the column direction and the position in the row direction The offset amount ΔY is substituted. Then, Ex and Ey in Equation 2 have the smallest coefficient αx. βx, γx, αy, βy, and γy are obtained.

[Equation 2] Ex = Σ (αx‧Xb + βx‧Yb + γx- △ X) ² Ey = Σ (αy‧Xb + βy‧Yb + γy- △ Y) ²

If the coefficient of the offset calculation formula is obtained, the position Xb in the column direction and the position Yb in the row direction of the center pixel of each uncomfortable area (the white divided area 60 in FIG. 10) are substituted into the offset calculation formula. . Thereby, the positional shift amount ΔX in the column direction and the positional shift amount ΔY in the row direction are obtained for the uncomfortable area (step S16). As mentioned above, the coefficients αx, βx, γx, αy, βy, and γy of the offset calculation formula are based on the position offsets of the plurality of adaptive regions, and the positions of the column directions and the row directions of the plurality of adaptive regions. Come to find out. In addition, the position shift amount of the uncomfortable area is obtained by using the shift amount calculation formula using the position in the column direction and the row direction of the uncomfortable area. Therefore, the positional shift amount of the uncomfortable area can be substantially determined as the position shift amount of the plurality of adaptive areas and the positional relationship between the uncomfortable area and the plurality of adaptive areas.

In the inspection unit 42, for example, a state in which the center pixel of each divided region 60 of the reference image 6 is arranged at a position shifted only by the position shift amount of the corresponding divided region 60 from the center pixel 51 a of the corresponding inspected divided region 50. Next, a difference area image showing the difference between the divided area 60 and the image under inspection is acquired. The difference area image is a mutually exclusive or (in the reference image 6 and the inspected image that has been aligned, showing the values of the pixels of the divided area 60 and the values of the pixels of the inspected image that overlap the pixel or ( exclusive or; XOR). The difference area image shows missing line candidate pixels. When the size of the set of adjacent defective candidate pixels is larger than a predetermined area threshold, the set of defective candidate pixels is detected as a defective area.

In another example of the processing performed by the inspection unit 42, the width of the pattern area or the width of the background area is obtained as the pattern width or the background width at each position of the inspected image. Further, in the pattern inspection device 1, threshold values of widths are set with respect to each position of the reference image 6, and the reference image 6 and the inspected image which have been aligned acquire and compare with the inspected image. Threshold value of the position of the reference image 6 where the positions overlap. Then, the pattern width or background width of the position of the inspected image is compared with the threshold value, thereby determining whether the position of the inspected image is a defect. As described above, the inspection unit 42 uses the position shift amount of each of the divided areas 60 to obtain the inspection result with respect to the inspected image while aligning the reference image 6 and the inspected image (step S17).

When the inspection of the first substrate 9 is completed, the second substrate 9 included in the target lot is captured by the imaging unit 213 to obtain an image to be inspected (steps S18 and S13). Next, in the same manner as described above, the position shift amount of the adaptive region is obtained, and the coefficient of the shift amount calculation formula is obtained (steps S14 and S15). Since the plurality of substrates 9 included in the target lot are based on the same design data 48, the appropriate regions of the divided region group are the same in the plurality of substrates 9. Then, the position shift amount of the uncomfortable area is obtained, and the inspection results are obtained from the reference image 6 and the inspected image that have been positioned (steps S16, S17). If the above-mentioned steps S13 to S17 are performed on all the substrates 9 included in the target lot, the processing of the pattern inspection device 1 ends (step S18).

Here, a pattern inspection device of a comparative example that performs offset amount acquisition processing on all the divided regions 60 of the divided region group will be described. In the pattern inspection device of the comparative example, for example, the offset acquisition process is also performed on the three divided regions 60 in FIG. 9. The patterns of the divided regions 60 in the upper, middle, and lower sections of FIG. 9 are each composed of only linear pattern elements extending in the column direction, the row direction, and the oblique direction. Therefore, as shown in the upper, middle, and lower sections of FIG. 13, in the pixel arrangement 510 of M columns and N rows centered on the center pixel 51a of the segmentation area 50 to be inspected, the specific pixels 51 marked with parallel oblique lines are respectively along the column direction , Row direction and oblique direction. As a result, it is difficult to accurately obtain the position shift amount in the direction in which the specific pixels 51 are arranged. If the vector obtained from the center pixel 51a of the segmentation area 50 to be inspected as the position shift amount is directed to the position of the center of gravity in the specific pixel group, the reliability of the position shift amount is very low, and will be obtained by the inspection section 42. In the inspection result of the divided area 60 to be inspected, there is often an error message that a portion that is not a defect is detected as a defect. The same applies when the divided area 60 displays other patterns having periodicity in one direction.

On the other hand, the pattern of the divided area 60 including the pattern concave portion 63 or the pattern convex portion 64 is not merely a linear pattern element extending in one direction. In other words, in the divided region 60 (refer to FIG. 8) in which the concave or convex pixel is detected, the concave or convex pixel becomes a characteristic point of the pattern shown in the divided region 60, and the specific pixel 51 is placed in the above-mentioned manner. It is difficult to arrange a pixel array 510 in M columns and N rows. In fact, the more the number of concave pixels and convex pixels included in each divided area 60, that is, the greater the number of feature points, the more difficult it is to arrange specific pixels 51 in a row. The number of concave pixels and convex pixels is expressed The degree of suitability of the division area 60 for the offset acquisition processing.

In the pattern inspection device 1, the suitability of each divided region 60 with respect to the offset acquisition process is obtained, and a plurality of adaptive regions are specified from the divided region group, and the respective suitability is acquired by the offset acquisition process. The position offset of the area. Then, for the uncomfortable area, the position shift amount is obtained based on the positional shift amounts of the plurality of adaptive regions and the positional relationship between the uncomfortable region and the plurality of adaptive regions. In this way, the position offset of the unsuitable region that is not suitable for the offset acquisition process is obtained by using the position offset of the appropriate region that is suitable for the offset acquisition process, so that the reference image 6 can be accurately obtained. And the amount of positional deviation of each of the divided areas 60 of the image under inspection. In addition, since the offset acquisition processing is performed only on a plurality of adaptive regions, the processing amount of the position offset acquisition unit 413 can be reduced compared to the case where the offset acquisition processing is performed on all the divided regions 60, that is, The time required to obtain the position offset can be shortened.

In the shift amount acquisition process, the difference between the adaptive region and the image under test is obtained while moving each adaptive region of the reference image 6 up, down, left, and right. This makes it possible to easily obtain the position shift amount of the adaptive region. In addition, an offset calculation formula that sets the position of each divided region 60 as a parameter is set in advance, and the offset calculation formula is obtained based on the position offsets of the plurality of adaptive regions and the positions of the plurality of adaptive regions. Coefficient. Thereby, the position shift amount of the uncomfortable area can be quickly obtained.

The inspection unit 42 uses the positional shift amount of each of the divided areas 60 to obtain the inspection result of the inspection image while aligning the reference image 6 and the inspection image. At this time, by aligning the reference image 6 and the inspected image for each of the divided regions 60, the inspection result of the inspected image can be accurately obtained (reduced error information).

Various modifications can be made in the above-mentioned position shift amount acquisition device 41 and pattern inspection device 1.

In the adaptive region specifying unit 412, although the concave pixels and the convex pixels are used as feature points, the feature points included in the pattern shown in each divided region 60 are detected, thereby achieving easy calculation of the pair of divided regions 60. The offset obtains the suitability of the process, but the characteristic points may be other than the concave pixels and the convex pixels. For example, in the pattern shown in each of the divided regions 60, a vertex of a polygonal figure as a pattern element or a curved portion (excluding a straight line) of an edge of the pattern element may be processed as a feature point. In addition, the degree of fitness can also be determined by methods other than the detection of feature points.

The image segmentation unit 411 may also obtain a segmented area group of the image to be inspected. In this case, a plurality of adaptive regions are specified from the divided region group to obtain an offset amount of the difference between each adaptive region and the reference image 6. As described above, in the pattern inspection apparatus 1, one of two images of the inspected image and the reference image 6 is divided to obtain a segmented area group, and the segmented area group is specified to be suitable for the biased area. A plurality of adaptive regions are processed by the displacement acquisition process. Further, in the offset acquisition process, the respective adaptive regions of the one image are moved up, down, left, and right, and the difference between the adaptive region and the other of the two images is obtained to obtain the difference. Position offset of the adaptive region.

On the other hand, in the case where a defect or the like is included in the inspected image obtained by capturing the substrate 9, it is impossible to accurately determine the suitability of the divided region. Therefore, from the viewpoint of accurately determining the suitability of each divided region, it is preferable to obtain the divided region group from the reference image 6 derived from the design data 48 of the display design pattern. Moreover, in the case where an actual pattern is formed in the plurality of substrates 9 based on the same design data 48, the division area group can be obtained by using the reference image 6 derived from the design data 48, and the plurality of substrates 9 can be obtained. For the images to be inspected, the inspection of the plurality of substrates 9 is performed efficiently using the same adaptive region.

As the offset amount obtaining process for obtaining the positional offset amount between the two images, a method other than the method described with reference to FIGS. 11 and 12 may be used. In the offset obtaining process, various methods related to pattern matching (for example, a normalized correlation method, etc.) can be adopted.

In the above embodiment, although the position shift amount between the inspected image obtained by digitizing the actual pattern image and the binarized reference image 6 is obtained, it is regarded as the inspected in the shift amount acquisition process. The image can also use multiple layers of actual pattern images. In this case, for example, an image of a design pattern obtained by assigning the average value of the pattern region and the average value of the background region to the pattern region 61 and the background region 62 as the reference image is generated as a reference image. Then, the above-mentioned processing using the position shift amount obtaining device 41 is performed on the multi-layered inspected image and the reference image. Similarly, the inspection unit 42 can obtain inspection results for a multi-level inspection image.

The offset calculation formula of Formula 1 is only an example, and a quadratic or higher-order formula can also be used. In addition, the position shift amount calculation unit 414 may obtain the position shift amount of the uncomfortable area without using the shift amount calculation formula. For example, the uncomfortable area can also be calculated by using the position offset of a plurality of uncomfortable areas located around each uncomfortable area and the positional relationship between the appropriate area and the uncomfortable area. The position offset.

The substrate to be inspected by the pattern inspection device 1 may be a semiconductor substrate, a glass substrate, or the like. In addition, in the pattern inspection device 1, in addition to a substrate, a thin-film object, a three-dimensional object, and the like can be inspected.

The position offset obtaining device 41 for obtaining the position offset of the two images can also be used for a drawing device and the like, and can be used to obtain the position offset of various types of images.

The configurations of the above-described embodiment and each modification can be appropriately combined as long as they do not contradict each other.

Although the invention has been described in detail, the foregoing description is for illustration only and is not intended to be limiting. Therefore, without departing from the scope of the present invention, various modifications and aspects can be realized.

Claims (12)

A position shift amount obtaining device includes: an image dividing unit that divides one of two images to obtain a divided region group; and an adaptive region specifying unit that obtains each divided region with respect to obtaining the 2 The positional amount of the positional offset amount between the images is obtained as the suitability of the process, thereby identifying a plurality of adaptive regions suitable for the above-mentioned offset amount acquisition process from the segmented area group; Performing the above-mentioned offset amount acquisition processing between the two images in each of the adaptive regions, thereby obtaining the positional offset amount of the respective adaptive regions; and a positional offset amount calculating unit, which Each of the discomfort regions included in the plurality of adaptive regions is obtained based on a position shift amount of the plurality of adaptive regions and a positional relationship between the discomfort regions and the plurality of adaptive regions. For example, the position deviation amount acquiring device according to claim 1, wherein the suitability region specifying unit obtains the suitability degree by detecting feature points included in a pattern shown in each of the divided regions. A position shift amount obtaining device includes: an image dividing unit that divides one of two images to obtain a divided region group; and an adaptive region specifying unit that obtains each divided region with respect to obtaining the 2 The positional amount of the positional offset amount between the images is obtained as the suitability of the process, thereby identifying a plurality of adaptive regions suitable for the above-mentioned offset amount acquisition process from the segmented area group; Performing the above-mentioned offset amount acquisition processing between the two images in each of the adaptive regions, thereby obtaining the positional offset amount of the respective adaptive regions; and A position shift amount calculation unit, for the unsuitable regions in the divided region group not included in the plurality of adaptive regions, based on the position shift amounts of the plurality of adaptive regions, and the discomfort region and the plurality of adaptive regions. Positional relationship to determine the position offset; the above-mentioned one image is an image derived from the design data of the display design pattern, and the other one of the two images is formed by shooting based on the above-mentioned The image obtained by designing the actual object of the material. A position shift amount obtaining device includes: an image dividing unit that divides one of two images to obtain a divided region group; and an adaptive region specifying unit that obtains each divided region with respect to obtaining the 2 The positional amount of the positional offset amount between the images is obtained as the suitability of the process, thereby identifying a plurality of adaptive regions suitable for the above-mentioned offset amount acquisition process from the segmented area group; Performing the above-mentioned offset amount acquisition processing between the two images in each of the adaptive regions, thereby obtaining the positional offset amount of the respective adaptive regions; and a positional offset amount calculating unit, which The discomfort areas included in the plurality of adaptive areas are obtained based on the positional offsets of the plurality of adaptive areas and the positional relationship between the discomfort areas and the plurality of adaptive areas; In the shift amount acquisition process, the difference between the respective adaptive region and the other of the two images is obtained while moving the respective adaptive regions of the one image up, down, left, and right. Thereby, the above-mentioned position shift amount of each of the adaptive regions is obtained. For example, the position offset obtaining device according to any one of claims 1 to 4, wherein a calculation formula of the position offset using the position of each of the divided regions as a parameter is set in advance, The position shift amount calculation unit obtains a coefficient of the calculation formula based on the position shift amounts of the plurality of adaptive regions and the positions of the plurality of adaptive regions. An inspection device comprising: the position shift amount acquisition device described in any one of claims 1 to 5; and an inspection unit that uses the above-mentioned respective divided regions obtained by the position shift amount acquisition device. The position shift amount is obtained by performing an alignment of the two images and obtaining an inspection result of the inspected image included in the two images. A method for obtaining a position offset includes: a) a step of dividing one of two images to obtain a group of divided regions; and b) obtaining a position of each divided region with respect to obtaining between the two images The suitability of the offset obtaining process of the offset, thereby specifying a plurality of adaptive regions suitable for the above-mentioned offset obtaining process from the above-mentioned divided region group; c) performing the above two in each adaptive region A process of obtaining the above-mentioned offset amount between the images, thereby obtaining the positional offset amount of each of the adaptive regions; and d) for each of the unsuitable regions in the divided region group not included in the plurality of adaptive regions, according to And a step of obtaining the positional shift amount by the positional shift amounts of the plurality of adaptive regions and the positional relationship between the respective uncomfortable regions and the plurality of adaptive regions. For example, the method for obtaining a position shift amount of claim 7, wherein in the step b), the above-mentioned suitability is obtained by detecting feature points of a pattern included in each of the divided regions. A method for obtaining a position offset includes: a) a step of dividing one of two images to obtain a group of divided regions; and b) obtaining a position of each divided region with respect to obtaining between the two images Of the offset The degree of suitability of the offset obtaining process, thereby specifying a plurality of suitable regions suitable for the above-mentioned offset obtaining process from the above-mentioned divided region group; c) in each of the adaptive regions, performing the above-mentioned two images. The step of obtaining the above-mentioned offset amount, thereby obtaining the positional offset amount of each of the adaptive regions; and d) for the unsuitable regions in the divided region group that are not included in the plurality of adaptive regions, according to the plurality of adaptive regions The positional deviation amount and the positional relationship between the discomfort area and the plurality of adaptability areas to obtain the position deviation amount; the above-mentioned image is an image derived from design data showing a design pattern, and The other of the two images is an image obtained by photographing an object on which an actual pattern based on the design data is formed. A method for obtaining a position offset includes: a) a step of dividing one of two images to obtain a group of divided regions; and b) obtaining a position of each divided region with respect to obtaining between the two images The suitability of the offset obtaining process of the offset, thereby specifying a plurality of adaptive regions suitable for the above-mentioned offset obtaining process from the above-mentioned divided region group; c) performing the above two in each adaptive region The step of obtaining the above-mentioned shift amount between images, thereby obtaining the position shift amount of each of the above-mentioned adaptive regions; and d) for the unsuitable regions in the divided region group that are not included in the plurality of appropriate regions, according to the above A step of obtaining a position shift amount by a position shift amount of a plurality of adaptive regions and a position relationship between the discomfort region and the plurality of adaptive regions; The above-mentioned respective adaptive regions are moved up, down, left and right, and the difference between the respective adaptive regions and the other one of the two images is obtained, thereby obtaining the position shift amount of the respective adaptive regions. If the position offset obtaining method of any one of claims 7 to 10 is used, The position shift amount of each of the divided regions is set as a parameter in advance, and the step d) is provided with the position shift amount of the plurality of adaptive regions and the positions of the plurality of adaptive regions to obtain the equation. Step of the coefficient. An inspection method comprising: the position shift amount acquisition method described in any one of claims 7 to 11; and using the position shift amount of each of the divided regions obtained by the position shift amount acquisition method. , While performing the alignment of the two images described above, a step of obtaining an inspection result of the inspected images included in the two images.