KR20070122363A - Unevenness inspecting apparatus and unevenness inspecting method - Google Patents

Abstract

A spot inspection apparatus and a method are provided to improve accuracy by checking striped spots extended in a direction of a circular center about a rotation shaft. A spot inspection apparatus checking striped spots on a film formed on a main surface of a board by supplying coating liquid on the main surface and rotating the board about a rotation shaft perpendicular to the main surface, comprises: a photographing unit and an estimation value acquisition unit. The photographing unit acquires variable images of objects by photographing the film of the board using a photographing device. In addition, the estimation value acquisition unit acquires a plurality of estimation values by integrating values of pixels arranged in directions respectively corresponding to directions of a plurality of circular centers.

Description

Stain Tester and Stain Checking Method {UNEVENNESS INSPECTING APPARATUS AND UNEVENNESS INSPECTING METHOD}

1 is a diagram illustrating a configuration of a stain inspection apparatus.

2 is a view showing a light receiving surface of an imaging unit;

3 is a diagram showing the configuration of a computer.

4 is a block diagram showing a functional configuration realized by a computer.

Fig. 5 is a view showing a flow of a process in which a spot inspection apparatus inspects a stripe spot on a film of a substrate.

6 is a diagram illustrating a target image.

7 is a diagram for explaining a plurality of centrifugal directions set on a substrate.

8 is a diagram illustrating a converted image.

9 is a view showing a rectangular area in a target image.

10 is a diagram illustrating a plurality of evaluation values for a plurality of Tokyo directions.

Fig. 11 is a diagram for explaining another example of operation in which the image capturing unit acquires a target image.

TECHNICAL FIELD The present invention relates to a technique for inspecting streaks of unevenness on a film formed on a substrate.

Conventionally, when forming a predetermined pattern on the main surface of a glass substrate for a display device or the like (hereinafter simply referred to as a "substrate"), the spin coater is perpendicular to the main surface while applying a resist liquid onto the main surface of the substrate. A resist film is formed by rotating a board | substrate about a rotating shaft, and Unexamined-Japanese-Patent No. 2006-49630 acquires the image of the board | substrate immediately after application | coating of the resist liquid by a spin coater, and coat | coated spots on the main surface of a board | substrate. A technique for inspecting is proposed.

In addition, Japanese Patent Laid-Open No. 9-68502 (Document 1) describes a pixel arranged in the other direction at each position in one direction among the arrangement directions of pixels orthogonal to each other in an image showing a shadow mask. Determination of the quality of the shadow spots on the shadow mask based on standardized data obtained by integrating the values to obtain integrated data and dividing each value of the integrated data by the corresponding value of the smoothed data obtained by smoothing the integrated data ( In other words, a technique of determining whether a defect is present or not is disclosed. Further, in Japanese Patent Laid-Open No. 6-261864, in an image obtained by imaging corneal endothelium, the average value of the values of pixels arranged in each long direction centered on a target pixel specified by a predetermined process. The method of obtaining the outline line of a corneal endothelial cell is calculated | required by calculating | requiring the, the function of the evaluation value represented by a longitude direction as a variable, and specifying the longitude direction in which the code of a differential coefficient changes.

However, when the resist film is formed, for example, if there is a microfluidic substance on the substrate immediately before the resist liquid is applied, the streaks unevenly stretched along the centrifugal direction around the axis of rotation with the unwanted substance as the resist It may occur on a film. In this case, it is difficult to accurately check the presence of streaks even if the integrated data obtained by integrating the pixel values in the pixel array direction is obtained as in the method of Document 1. Therefore, there is a need for a novel method capable of accurately confirming the presence of streaks unevenly extending in the centrifugal direction about the rotation axis on the film of the substrate.

The present invention is suitable for a stain inspection apparatus for inspecting streaks on the film formed on the main surface by supplying a coating liquid onto the main surface of the substrate and rotating the substrate about a rotation axis perpendicular to the main surface. Therefore, an object of the present invention is to accurately and easily confirm the presence of streaks unevenly extending in the centrifugal direction about the rotation axis.

In the spot inspection apparatus according to the present invention, an image pickup device captures a film of a substrate with an imaging device, and a plurality of centrifugal directions are directed on the main surface toward the outside with a rotation axis as a viewpoint on the main surface. And an evaluation value acquisition unit for acquiring a plurality of evaluation values corresponding to the plurality of centrifugal directions by integrating the values of pixels arranged in the directions corresponding to the plurality of centrifugal directions in the target image.

According to the present invention, the presence of streaks unevenly stretched in the centrifugal direction about the rotation axis on the film of the substrate can be accurately and easily confirmed by referring to the evaluation value.

In a preferable embodiment of the present invention, a plurality of annular regions are set around the rotational axis on the main surface, and each of the annular regions is along the direction corresponding to each of the plurality of centrifugal directions in the target image. The evaluation value is obtained by integrating the values of the pixels existing in the range corresponding to the entire width of. As a result, the influence of the length of the striped spot on the evaluation value can be suppressed, and the presence of the striped spot having a high spot strength, that is, easily recognized as a spot can be easily confirmed.

More preferably, a part of each annular region overlaps with a part of any other annular region with respect to the radial direction, and another annular region is set over the boundary between two annular regions adjacent to each other. Thereby, presence of the stripe unevenness with high uneven intensity | strength can be confirmed accurately.

According to another preferred embodiment of the present invention, the arrangement directions of the pixels orthogonal to each other in the target image correspond to two directions orthogonal to each other on the main surface of the substrate, respectively, and the evaluation value acquisition unit determines the position corresponding to the rotation axis in the target image. An evaluation value can be easily calculated | required by generating the converted image which converted the polar coordinate system made into the center into a rectangular coordinate system, and obtaining a plurality of evaluation values from the converted image.

로 하여, 피치각이, arctan (1/

) 이하이다. 이에 의해, 변환 화상을 정밀도 있게 생성할 수 있다. More preferably, a plurality of centrifugal directions are set at a constant pitch angle, and half of the number of pixels arranged on the long side of the target image is set.

The pitch angle is arctan (1 /

) As a result, the converted image can be generated with precision.

The present invention is also suitable for a spot inspection method for inspecting streaks spots on a film formed on a substrate.

The above object and other objects, features, states, and advantages will become apparent from the following detailed description of the present invention made with reference to the accompanying drawings.

1 is a diagram showing the configuration of a spot inspection apparatus 1 according to an embodiment of the present invention. The spot inspection apparatus 1 is an image of the film 92 of the pattern forming resist formed on one main surface 91 in a rectangular glass substrate 9 used for a flat panel display such as a liquid crystal display. Is obtained and the streaks unevenness on the film 92 of the substrate 9 are inspected based on this image. Here, the film 92 on the substrate 9 is formed by a spin coat method. Specifically, after the resist liquid is supplied to the stationary substrate, the substrate is rotated about a rotation axis perpendicular to the main surface. It is formed by supplying a resist liquid onto a rotating substrate (so-called a static method) or by increasing the rotation speed of the substrate (so-called dynamic method). That is, the film 92 on the substrate 9 is supplied with a resist liquid on the main surface 91 in an external spin coater, and the substrate 9 is rotated about a rotation axis perpendicular to the main surface 91. Formed. In addition, the static method and the dynamic method have a central dropping method for supplying a resist liquid to the center of the main surface of the substrate. In addition, in the static method, in addition to the central dropping method, a slit nozzle is provided relative to the substrate along the main surface of the substrate. There is also a so-called slit-and-spin method in which the resist liquid is discharged in a layer while moving, the resist liquid is supplied to a rectangular region excluding the outer edge portion on the main surface, and the substrate is rotated.

As shown in FIG. 1, the spot inspection apparatus 1 has a main surface 91 (hereinafter referred to as an "top surface 91") on which a film 92 is formed (upper side (+ Z) in FIG. 1). The stage 2 holding the substrate 9 toward the side, the light irradiation unit 3 and the light irradiation unit 3 irradiating light at a predetermined angle of incidence to the film 92 on the substrate 9 held on the stage 2. The light-receiving unit 4, the stage 2, which receives light reflected from the film 92 on the upper surface 91 of the substrate 9 and is reflected from the light-receiving unit 3 and the light-receiving unit 4. The moving mechanism 21 which moves, and the computer 5 which functions as a control part of the spot test | inspection apparatus 1 are provided.

The surface on the (+ Z) side of the stage 2 is preferably black matt. The moving mechanism 21 has a structure in which a ball screw (not shown) is connected to the motor 211, and the stage 2 is along the guide 212 so that the stage 2 rotates along the guide 212 when the motor 211 rotates. It moves to the X direction in FIG. 1 along 91. FIG.

The light irradiator 3 is a halogen lamp 31 which is a light source that emits white light (that is, light including light of all wavelengths in the visible region) in the Y direction in FIG. 1 perpendicular to the moving direction of the stage 2. And a cylindrical quartz rod 32 extending therein, and a cylindrical lens ((Cy1indrical Lens) 33) extending in the Y direction. In the light irradiation part 3, the halogen lamp 31 is attached to the edge part of the (+ Y) side of the quartz rod 32, and the light which entered the quartz rod 32 from the halogen lamp 31 is Y direction. Is converted into linear light (ie, light whose cross section is long in the Y direction) and is emitted from the side of the quartz rod 32, and the upper surface of the substrate 9 through the cylindrical lens 33 91). In other words, the quartz rod 32 and the cylindrical lens 33 convert the light from the halogen lamp 31 into linear light perpendicular to the moving direction of the stage 2 so that the top surface 91 of the substrate 9 It is an optical system leading to.

In FIG. 1, the optical path from the light irradiation part 3 to the board | substrate 9 is shown by the dashed-dotted line (the same also about the optical path from the board | substrate 9 to the light receiving unit 4). A part of the light emitted from the light irradiation part 3 is reflected by the upper surface on the (+ Z) side of the film 92 on the upper surface 91 of the substrate 9. The film 92 is light-transmissive with respect to the light from the light irradiator 3, and light that is not reflected from the upper surface of the film 92 among the light from the light irradiator 3 passes through the film 92. A portion of the upper surface 91 of the substrate 9 (ie, the lower surface of the film 92) is reflected. In the spot inspection apparatus 1, interference light between light reflected from the upper surface of the film 92 on the substrate 9 and light reflected from the upper surface 91 of the substrate 9 is transmitted to the light receiving unit 4. Incident, the interference light of a predetermined wavelength is guided to the imaging unit 41 through the filter 43 and the lens 42.

2 is a diagram illustrating a light receiving surface of the imaging unit 41. As shown in FIG. 2, the image pickup unit 41 is provided with a line sensor 410 having a plurality of light receiving elements (eg, CCD (Charge Coupled Device)) 411 arranged in a straight line in the Y direction. . In the imaging unit 41, the interference light from the substrate 9 is received by the line sensor 410, whereby the intensity distribution of the interference light (that is, the distribution in the Y direction of the output value from each light receiving element 411) is obtained. Is acquired. In practice, the intensity distribution of the interference light is repeatedly acquired by the line sensor 410 of the imaging unit 41 as the substrate 9 moves in the X direction, thereby producing a two-dimensional image of the film 92 on the substrate 9. Is acquired.

As shown in FIG. 3, the computer 5 is a general computer which connects the CPU 51 which performs various arithmetic processing, the ROM 52 which stores a basic program, and the RAM 53 which stores various information to a bus line. It is a system configuration. The bus line further includes a fixed disk 54 for storing information, a display 55 for displaying various information, a keyboard 56a for receiving input from an operator, and a mouse 56b (hereinafter referred to as an "input unit ( 56) "), a reading device 57 for reading information from a computer-readable recording medium 8 such as an optical disc, a magnetic disc, a magneto-optical disc, and another configuration of the spot inspection apparatus 1; The communication unit 58 connected to the element is appropriately connected via an interface (I / F) 59a, 59b, 59c or the like.

In the computer 5, the program 541 is read from the recording medium 8 via the reading device 57 in advance and stored in the fixed disk 54. Then, while the program 541 is copied to the RAM 53 and the CPU 51 executes arithmetic processing in accordance with the program in the RAM 53 (that is, the computer executes the program), the computer 5 is connected to the substrate. An operation as an operation unit for inspecting the streaks of spots on (9) is performed.

4 is a block diagram showing a functional configuration realized by the CPU 51, the ROM 52, the RAM 53, the fixed disk 54, etc., by operating the CPU 51 in accordance with the program 541. As shown in FIG. In FIG. 4, the image processing part 61, the evaluation value acquisition part 62, and the determination part 63 in the calculating part 6 are shown the function implemented by CPU51 etc. In FIG. In addition, these functions may be realized by a dedicated electrical circuit, or a dedicated electrical circuit may be used in part.

Next, the flow of the inspection of the striped stain by the stain inspection apparatus 1 will be described. FIG. 5 is a diagram showing a flow of processing in which the spot inspection apparatus 1 inspects streaks spots on the film 92 of the substrate 9. In the stain inspection apparatus 1, first, the inspection start position shown by the solid line in FIG. 1 of the board | substrate 9 in which the film | membrane 92 was formed on the upper surface 91 by provision of the resist liquid and rotation of the board | substrate 9. FIG. After being held on the stage 2 positioned at, the movement in the (+ X) direction of the stage 2 is started. Subsequently, the linear light emitted from the light irradiation part 3 and incident on the upper surface 91 of the substrate 9 at a predetermined angle of incidence is a linear irradiation area on the upper surface 91 (hereinafter, referred to as a "linear irradiation area"). Is irradiated), and the linear irradiation area is moved relative to the substrate 9. The light from the light irradiation section 3 is reflected on the upper surface 91 of the substrate 9, the interference light is directed to the imaging section 41, received by the line sensor, and in the linear irradiation area on the substrate 9. The intensity distribution of the interference light of is obtained. The output from each light receiving element 411 of the line sensor is sent to the computer 5 while being converted to, for example, a value (pixel value) of 8 bits (of course, other than 8 bits) based on a predetermined conversion formula.

In the spot inspection apparatus 1, while the stage 2 is moving in the (+ X) direction, the intensity distribution of the interference light in the imaging unit 41 is acquired, and the pixel value is output to the computer 5. The operation is repeated in synchronization with the movement of the stage 2. When the stage 2 moves to the inspection end position, the movement of the stage 2 by the moving mechanism 21 is stopped, and the irradiation of the illumination light is also stopped. As described above, the imaging section 41 picks up the entirety of the film 92 on the substrate 9 and is a multi-dimensional two-dimensional image (as described below), which is an object to be processed by the calculation section 6. (Hereinafter referred to as a "target image") is obtained, input to the calculating section 6 of the computer 5, and ready (step S11).

Next, in the image processing unit 61 of the calculating unit 6, the target image is compressed. Here, when the pixel value of the pixel located at the coordinates (X, Y) in the target image is denoted by F _XY , the image generated by compressing the target image in units of the range of s _a pixels × s _a pixels (after compression In the target image), the pixel value A _xy of the pixel of interest located at the coordinates (x, y) is obtained by equation (1).

In the present embodiment, since s _a is 4 (pixels), the S / N ratio of the target image after compression is increased by four times the original target image by the calculation of equation (1). Then, a low pass filter process is performed on the target image after compression, and the influence of high frequency noise is suppressed from the target image after compression to produce a smoothed image (target image after low pass filter processing). The window for determining the operation range of the low pass filter processing is a pixel of the pixel of interest in which the length of one side is a square of (2s ₁ +1) pixels and is located at coordinates (x, y) in the target image after the low pass filter processing. The value L _xy is obtained by equation (2) using the pixel value A (see equation (1)) in the target image after compression of each pixel in the vicinity of the pixel of interest.

After that, the high pass filter process is performed on the target image after the low pass filter process, and the image from which the low frequency density fluctuations that hinder the contrast enhancement process described later is removed from the target image after the low pass filter process (after the high pass filter process). Target image) is generated. Here, the pixel value H ¹ _xy of the pixel of interest positioned at the coordinates (x, y) is the pixel value L in the target image after the low pass filter processing of each pixel in the vicinity of the pixel of interest (Formula (2). ) Is obtained by the formula (3).

Equation (3) is a window for determining the calculation range of the high-pass filter processing, and represents a case where a square window of (2s ₂ +1) pixels having a length of each side centered on the pixel of interest is used. As described above, the image processing unit 61 performs a low pass filter process on the compressed target image after compressing the original target image, and then performs a high pass filter process to thereby perform a band pass filter process of a predetermined spatial frequency band. Is performed (step S12).

In the image processing unit 61, contrast emphasis processing is performed on the target image after the high pass filter processing to generate the target image after the emphasis processing (step S13). The pixel value E _xy of the pixel of interest located at the coordinates (x, y) in the target image after the emphasis processing is the pixel value (H ¹ _xy ), contrast of the pixel of interest in the target image after the high pass filter processing. It is calculated | required by Formula (4) using the coefficient r _c and background value b. In this embodiment, r _c is 0.01, 0.02, 0.05 or 0.1, and b is 127.

6 is a diagram illustrating the target image 71 after the emphasis processing. Here, the target image 71 (hereinafter, simply referred to as the "target image 71") after the emphasis processing becomes an image of 256 gray levels, and the average density of the target image 71 (that is, the average value of the pixel values). Is about 127. Moreover, on the film 92 of the board | substrate 9 from which the target image 71 was acquired, the stripe unevenness extended by making the rotation axis into the viewpoint in the direction which a centrifugal force acts at the time of rotation of the board | substrate 9 (detected by the following process) 6), the high density (black) stripe region and the low density (white) stripe region are centered in the target image 71 of FIG. 6. Is a position corresponding to the rotation axis of the substrate 9. However, in practice, streaks unevenly elongate in the direction in which the centrifugal force acts on the film of the substrate at a position other than the rotation axis. It may occur.

Subsequently, in the converted image generation unit 621 of the evaluation value acquisition unit 62, the rotation axis of the substrate 9 when forming the film 92 in the target image 71 (hereinafter, simply referred to as “substrate 9”). Rotation axis ". A converted image obtained by converting the polar coordinate system centered on the position corresponding to the rectangular coordinate system into a rectangular coordinate system is generated (step S14).

In the generation of the converted image, first, in the target image 71 of FIG. 6 in which pixels are arranged in the x direction and the y direction, a position corresponding to the rotation axis J1 of the substrate 9 shown in FIG. 7 (hereinafter, “ Center position. &Quot;) coordinates (cx, cy) are specified. Here, since the target image 71 is acquired around the rotational axis J1 of the board | substrate 9, as shown in FIG. 6, the center of the target image 71 becomes the center position C1. Subsequently, the distance between the position farthest from the center position C1 and the center position C1 in the target image 71 (hereinafter referred to as "maximum length") is obtained. As described, since the center position C1 is the center of the target image 71, the maximum length is equal to half of the diagonal length of the target image 71, and the x and y directions of the target image 71 are as follows. Using the length (number of pixels) of x ₁ and y ₁ , respectively, the maximum length K _max is obtained by equation (5).

로 하여, arctan(1/

)에 의해 얻어지는 값으로 된다. 또, 동경 방향의 개수(β)는, 360[도]를 피치각(P)[도]로 제산한 값으로 된다. 변환 화상 생성부(621)에서는, 예를 들면, (+x) 방향을 나타낸 동경 방향(도 6 중에서 부호 DO를 붙이는 화살표로 나타낸다.)을 기준이 되는 O번째의 동경 방향(이하, 「기준 동경 방향」이라고 한다.)으로서 규정함으로써, 반시계 방향을 정으로 하여 피치각(P)으로 차례로 설정되는 복수의 동경 방향 중, m번째(단, m은 0 이상이면서 (β-1) 이하의 정수)의 동경 방향(도 6 중에서 부호 Dm를 붙이는 화살표로 나타낸다.)의 기준 동경 방향에 대한 각도 위치(θ_m)가 (m×P)으로서 구해진다.In the converted image generating unit 621, a plurality of radial directions are directed outward from the center position C1 in the target image 71. Here, the plurality of radial directions are set to a constant pitch angle, and the pitch angle P (degrees) is half of the number of pixels y ₁ arranged in the y direction along the long side of the target image 71.

Arctan (1 /

It becomes the value obtained by The number β in the radial direction is a value obtained by dividing 360 [degrees] by the pitch angle P [degrees]. In the converted image generating unit 621, for example, the O-th Tokyo direction (hereinafter referred to as "reference Tokyo") which serves as a reference to the Tokyo direction (indicated by an arrow denoted by DO in FIG. 6) showing the (+ x) direction. Direction ”.) M-th (but m is an integer equal to or greater than 0 and equal to or less than (β-1)) among a plurality of radial directions that are sequentially set at the pitch angle P with the counterclockwise direction positive ), The angular position θ _{m with} respect to the reference radial direction in the radial direction (indicated by an arrow denoted by reference numeral Dm in FIG. 6) is obtained as (m × P).

로 하여, arctan(1/

)에 의해 얻어지는 값이 된다. 도 7에서는 2개의 원심방향을, 도 6 중의 대응하는 동경 방향과 같은 부호를 붙이는 화살표(D0, Dm)로 나타내고 있다. In addition, as described above, the center position C1 in the target image 71 corresponds to the rotation axis J1 of the substrate 9 shown in FIG. 7, and the arrangement direction of pixels orthogonal to each other in the target image 71. Since silver corresponds to two directions orthogonal to each other on the upper surface 91 of the substrate 9, on the upper surface 91 of the substrate 9, a plurality of centrifugal directions facing outward with the rotational axis J1 as the starting point Can be understood to be set so as to correspond to the plurality of radial directions in the target image 71, and the pitch angles in the plurality of centrifugal directions and half of the number of pixels arranged in the long sides of the target image 71 are determined.

Arctan (1 /

It is a value obtained by In FIG. 7, two centrifugal directions are indicated by arrows D0 and Dm denoted by the same reference signs as the corresponding radial directions in FIG. 6.

In this manner, when a plurality of radial directions in the target image 71 shown in FIG. 6 are set, the angular positions θ _m in the plurality of radial directions centering on the center position C1 in the target image 71, And a polar coordinate system defined by the distance n from the center position C1 along each radial direction (where n is an integer greater than or equal to and less than or equal to the maximum length K _max ), and the distance n along the radial direction ) And a converted image converted into a rectangular coordinate system defined by the number m in the radial direction corresponding to the angular position θ _m . Here, the value (pixel value) of the pixel located at the coordinate (n, m) in the converted image is the coordinate (x, in the target image 71 obtained by substituting the values of n and m in equation (6). It becomes the value of the pixel located in y). However, cx and cy are respectively the x-coordinate and y-coordinate of the center position C1 in the target image 71, and P is a pitch angle of a radial direction. In addition, when the coordinates (x, y) required by the formula (6) for any of the coordinates (n, m) in the converted image indicates the outside of the target image 71, the coordinates (n, m) The intermediate value (background value) 127 of the target image 71 is given to the pixel of the converted image.

FIG. 8 is a diagram illustrating a converted image 72 generated from the target image 71 of FIG. 6. In the converted image 72 of FIG. 8, the vertical direction and the horizontal direction correspond to the number m in the long direction and the distance n along the long direction, respectively. When the converted image 72 is generated, as shown in FIG. 9, in the evaluation value acquisition unit 62, each of the converted images 72 spans the entire vertical direction, and the width in the horizontal direction is W. FIG. A plurality of rectangular regions 73 (wherein, in Fig. 9, the plurality of rectangular regions 73 arranged in the horizontal direction are alternately shown as a solid rectangle and a dashed rectangle) are each of a width W. It is set in the horizontal direction at half the pitch (W / 2). Therefore, another rectangular region 73 (indicated by giving a parallel diagonal line in FIG. 9) is set over the boundary between two adjacent rectangular regions 73 (a dashed rectangle indicated by 73a in FIG. 9) while being in contact with each other. The width in the horizontal direction of the region where each rectangular region 73 overlaps with the other rectangular region 73 is half of the width (W / 2) of the rectangular region 73.

When a plurality of rectangular areas 73 are set in the converted image 72, the value obtained by integrating the values of the pixels arranged in the horizontal direction in each rectangular area 73 is divided by the number of the corresponding pixels (that is, the average value is As shown in FIG. 10, a plurality of evaluation values for a plurality of radial directions in each rectangular region 73 are obtained (step S15). 10, the vertical axis | shaft has shown the evaluation value, and the horizontal axis | shaft has shown the number of the east direction.

Here, the transverse direction in the converted image 72 corresponds to the distance in the radial direction (that is, the direction away from the rotation axis J1) around the rotation axis J1 on the upper surface 91 of the substrate 9. Therefore, as shown in FIG. 7, the plurality of rectangular regions 73 having the range of the width W at different positions with respect to the horizontal direction in the converted image 72 are upper surfaces 91 of the substrate 9. ) Corresponds to a plurality of annular regions 74 (but only some annular regions 74 are shown in FIG. 7) which occupy a range of width W at different positions with respect to the radial direction. . More specifically, similar to the rectangular region 73 in the converted image 72, the other annular region 74 across the boundary between two adjacent annular regions 74 (regions enclosed by broken lines in FIG. 7) which are in contact with each other. (The area | region which gives a parallel diagonal line in FIG. 7) exists, and a part of each annular area 74 overlaps with a part of any other annular area 74 about radial direction. Therefore, the above-mentioned process of integrating the values of the pixels arranged in the horizontal direction in each rectangular region 73 in the converted image 72 to obtain an evaluation value includes each of the plurality of radial directions in the target image 71. Therefore, it is equivalent to calculating the evaluation value by integrating the values of the pixels existing in the range corresponding to the entire width of each annular region 74.

When a plurality of evaluation values in each rectangular area 73 are obtained, the determination unit 63 determines each of the upper threshold value higher than the background value of the target image 71 and the lower threshold value lower than the background value. When the evaluation values are compared and the evaluation value of which is equal to or higher than the upper threshold value or becomes equal to or lower than the threshold value, the evaluation value is extended along the centrifugal direction on the film 92 of the substrate 9, and It is determined that there are streaks uneven to be a defect (step S16). For example, in the graph shown in FIG. 10, the longitude direction of the number whose evaluation value becomes more than the upper threshold value T1 or less than the lower threshold value T2 corresponds to the stripe unevenness which should be made into a defect. Thus, in the determination part 63, of the stripe unevenness on the film | membrane 92 of the board | substrate 9, the density | concentration of the corresponding pixel group in the target image 71, and the background value (average density) of the target image 71 Stripe unevenness having a large absolute value (hereinafter also referred to as "stain strength") is detected as a streaked spot defect, and the fact that streaked spot defects exist on the film 92 of the substrate 9 is displayed on the display 55. Is displayed and reported to the operator. In addition, confirmation of the presence of streaks (defects) extending along the centrifugal direction on the substrate 9 causes the computer 5 to display a graph (see FIG. 10) showing a plurality of evaluation values corresponding to the plurality of centrifugal directions. It may be performed by an operator, such as displayed at 55.

If necessary, the annular region 73 on the substrate 9 corresponding to the rectangular region 73 is obtained from the rectangular region 73 and the radial direction in which the evaluation value equal to or greater than the upper threshold value or the lower threshold value is obtained. 74 and the centrifugal direction on the board | substrate 9 corresponding to the said radial direction are specified, and the position on the board | substrate 9 in which at least one part of a stripe uneven defect exists is acquired. And the information which shows the said position is specified the cause of the generation | occurrence | production of a streak spot defect (for example, the identification of the cause, such as due to the pattern shape already formed on the board | substrate 9 before application | coating of a resist liquid), or It can be used for subsequent processing or management of the effects of streaks and defects on the final product.

As described above, in the spot inspection apparatus 1 of FIG. 1, the substrate 9 is included in the target image 71 obtained from the film 92 on the substrate 9 formed by application of a resist liquid and rotation of the substrate. The process of integrating the values of the pixels arranged in the direction corresponding to each of the plurality of centrifugal directions set on the upper surface 91 of the c) is performed, thereby obtaining a plurality of evaluation values corresponding to the plurality of centrifugal directions. As a result, streaks unevenly stretched along the centrifugal direction about the rotation axis J1 on the film 92 of the substrate 9 by referring to the evaluation value in the determination unit 63 (or by the operator). The presence of can be confirmed with precision and easily.

Moreover, in the spot inspection apparatus 1, the some annular area | region 74 centering on the rotating shaft J1 on the upper surface 91 of the board | substrate 9 is set. Here, if the evaluation value is acquired by integrating the values of all the pixels arranged along each Tokyo direction in the target image 71, the evaluation value of the long striped unevenness while the uneven intensity is low, and the uneven intensity is high and short The evaluation value of the streaks is almost the same, and it may be difficult to detect only the streaks with high spot strength. On the other hand, in the evaluation value acquisition part 62, the evaluation value is calculated | required by accumulating the value of the pixel which exists in the range corresponding to the whole width | variety of each annular area 74 in the target image 71 in the target image 71. As a result, the influence of the length of the streaks unevenness on the evaluation value can be suppressed, and it is possible to easily identify only the presence of streaks streaks having high spot strength. Further, the other annular region 74 is set across the boundary between two annular regions 74 adjacent to each other, so that the width of the annular region 74 can be compared with the two annular regions 74 adjacent to each other. Even when short streaks are present, the presence of such streaks can be accurately confirmed. In addition, in the above description, the staining intensity is based only on the density in the image, but in general, since the staining intensity is easily recognized as a staining, the length of the striped staining can also be added as an element of the staining intensity. .

In the spot inspection apparatus 1, as shown in FIG. 11, the imaging part 41 which has the line sensor 410 is arrange | positioned above the upper surface 91 of the board | substrate 9, and the rotating shaft ( Imaging is performed while rotating the line sensor 410 with respect to the board | substrate 9 with respect to the board | substrate 9 centering on J1), and a target image may be acquired. In this case, the plurality of pixels in each row of the target image respectively represent a plurality of positions arranged in the centrifugal direction on the substrate 9 corresponding to the rotation angle of the line sensor 410 when the pixels in the row are acquired. In the evaluation value acquisition unit, the plurality of evaluation values corresponding to the plurality of centrifugal directions can be easily obtained by integrating the values of the pixels arranged in the row direction at each position in the column direction of the target image.

Immediately after formation of the film 92 onto the substrate 9 by the spin coater, a line sensor is disposed above the substrate 9 placed on the stage of the spin coater, and the line sensor is rotated to rotate the stage. The target image may be acquired. In this manner, the rotation of the line sensor with respect to the film 92 on the substrate 9 at the time of acquisition of the target image may be relative, and the function of the spot inspection apparatus 1 may be combined with the spin coater.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

로 하여, arctan(1/

) 이하로 되는 것이라면, 다른 피치각이 채용되어도 된다. 이에 의해, 변환 화상을 정밀도 있게 생성할 수 있다. For example, the pitch angles of the plural centrifugal directions represent half of the number of pixels arranged on the long side of the target image 71.

Arctan (1 /

Other pitch angle may be employ | adopted if it becomes below). As a result, the converted image can be generated with precision.

Moreover, in the said embodiment, although another annular area | region 74 is set across the boundary of the two annular area | regions 74 which contact and mutually contact on the upper surface 91 of the board | substrate 9, mutually forming a gap, Another annular region 74 may be set over the boundary between two annular regions disposed adjacent to each other, and even in this case, it is possible to accurately confirm the presence of streaks unevenly located only in the vicinity of the boundary between the two annular regions. . Further, the plurality of annular regions may have different widths with respect to the radial direction centering on the rotational axis J1, and for example, the plurality of annular regions may be set so that the width becomes wider as they are disposed outside.

The evaluation value acquisition unit 62 corresponds to the plurality of centrifugal directions from the converted image 72 by extracting the values of pixels along each of the plurality of radial directions in the target image 71 to generate the converted image 72. Although a plurality of evaluation values can be easily obtained, a plurality of evaluation values corresponding to a plurality of centrifugal directions can be directly obtained from the target image 71 without generating the converted image 72.

If the values of the pixels arranged in the direction corresponding to each centrifugal direction are accumulated in the target image 71 or the converted image 72, the value itself in which the values of the pixels are integrated or the position of each pixel The weighted average value etc. which are calculated | required by giving weight may be an evaluation value.

In the spot inspection apparatus 1 of FIG. 1, a target image is acquired by linearly moving the board | substrate 9 with respect to the line sensor 410 which is a one-dimensional imaging device, but the line sensor 410 is linear with respect to the board | substrate 9 The target image may be acquired by moving. That is, the linear movement of the line sensor 410 with respect to the board | substrate 9 may be relative. Moreover, it is also possible to acquire a target image by imaging the film | membrane 92 of the board | substrate 9 with the two-dimensional imaging device in which the light receiving element was arrange | positioned two-dimensionally.

If the film on the substrate 9 is formed by a spin coat method, a coating liquid other than the resist liquid is applied on the main surface of the substrate 9 at the time of rotation of the substrate 9 or immediately before the start of rotation of the substrate 9. It may be formed by supplying. Moreover, the spot inspection apparatus 1 is particularly suitable for inspection of streaks spots on the film formed on the glass substrate for flat panel display devices. In other substrates such as a semiconductor substrate, It is also possible to use for the inspection of streaks.

While this invention has been described and described in detail, the foregoing description is by way of example and not restrictive. Accordingly, it is understood that many modifications and forms are possible without departing from the scope of this invention.

Claims (14)

A smudge inspection apparatus for supplying a coating liquid onto a main surface of a substrate and inspecting streaks on the film formed on the main surface by rotating the substrate about a rotation axis perpendicular to the main surface. An imaging unit which acquires a multi-gradation target image by imaging the film of the substrate with an imaging device. A plurality of centrifugal directions are set outward on the main surface with the rotation axis as a starting point, and the plurality of centrifugal directions are accumulated in the target image, and the values of the pixels arranged in the directions corresponding to each of the plurality of centrifugal directions are accumulated. And an evaluation value acquisition unit for acquiring a plurality of evaluation values corresponding to the centrifugal direction of the. The method according to claim 1, In the main surface, a plurality of annular regions around the rotation axis are set, Spot inspection in which the evaluation value obtaining unit calculates an evaluation value by integrating values of pixels existing in a range corresponding to the entire width of each annular region in a direction corresponding to each of the plurality of centrifugal directions in the target image; Device. The method according to claim 2, A spot inspection apparatus in which a part of each annular region overlaps a part of any other annular region in the radial direction. The method according to claim 3, A spot inspection apparatus in which a different annular region is set over a boundary between two annular regions adjacent to each other. The method according to claim 1, The spot inspection apparatus wherein the substrate is a glass substrate for a flat panel display. The method according to any one of claims 1 to 5, An arrangement direction of pixels orthogonal to each other in the target image corresponds to two directions orthogonal to each other on the main surface of the substrate, And the evaluation value obtaining unit generates a converted image obtained by converting a polar coordinate system centered on a position corresponding to the rotation axis in the target image into a rectangular coordinate system, and obtains the plurality of evaluation values from the converted image. The method according to claim 6, The plurality of centrifugal directions are set at a constant pitch angle, and half of the number of pixels arranged on the long side of the target image is determined.

The pitch angle is arctan (1 /

Stain inspection device of less than). A smudge inspection method for inspecting streaks on a film formed on the main surface by supplying a coating liquid onto a main surface of the substrate and rotating the substrate about a rotation axis perpendicular to the main surface. a) preparing a multi-gradation target image obtained from the film of the substrate; b) A plurality of centrifugal directions are set outward on the main surface with the rotation axis as a starting point, and by integrating the values of pixels arranged in directions corresponding to each of the plurality of centrifugal directions in the target image, And a step of acquiring a plurality of evaluation values corresponding to the plurality of centrifugal directions. The method according to claim 8, In the main surface, a plurality of annular regions around the rotation axis are set, In the step b), in the target image, an evaluation value is obtained by integrating the values of pixels existing in a range corresponding to the entire width of each annular region along a direction corresponding to each of the plurality of centrifugal directions. How to check stains. The method according to claim 9, A spot inspection method in which a part of each annular region overlaps with a part of any other annular region in the radial direction. The method according to claim 10, A smudge inspection method in which different annular regions are set over a boundary between two annular regions adjacent to each other. The method according to claim 8, The speckle inspection method wherein the substrate is a glass substrate for a flat panel display device. The method according to any one of claims 8 to 12, An arrangement direction of pixels orthogonal to each other in the target image corresponds to two directions orthogonal to each other on the main surface of the substrate, In the step b), a blot inspection in which a converted image obtained by converting a polar coordinate system centered on a position corresponding to the rotation axis in the target image into a rectangular coordinate system is generated, and the plurality of evaluation values are obtained from the converted image. Way. The method according to claim 13, The plurality of centrifugal directions are set at a constant pitch angle, and half of the number of pixels arranged on the long side of the target image is determined.

The pitch angle is arctan (1 /

) Speckle inspection method that is less than.

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