JP2008003018A - Irregularity inspecting device and irregularity inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and easily confirm the presence of stripe irregularities, extending in the centrifugal direction which is centered about a rotating axis on the film of a substrate, formed by the application of a coating solution and rotation of the substrate. <P>SOLUTION: The film on the substrate is formed, by applying a resist solution to the main surface of the substrate in an outside spin coater and rotating the substrate centering around the rotating axis that is vertical to its main surface; and in the irregularity inspecting device, a plurality of evaluation values, corresponding to a plurality of centrifugal directions, are acquired by integrating the values of pixels arranged in the radial directions, respectively, corresponding to a plurality of the centrifugal directions set on the upper surface of the substrate that is centered about the rotary axis in the target image 71 obtained from the film on the substrate. As a result, the existence of the stripe irregularities, extending along the centrifugal directions, on the film of the substrate centered about the rotating axis can be accurately and confirmed easily by referring to the evaluation values. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for inspecting streaks on a film formed on a substrate.

  Conventionally, when a predetermined pattern is formed on the main surface of a glass substrate or the like (hereinafter simply referred to as “substrate”) for a display device, a resist solution is applied to the main surface of the substrate with a spin coater. A resist film is formed by rotating a substrate about a rotation axis perpendicular to the surface. In Patent Document 1, an image of a substrate immediately after application of a resist solution by a spin coater is acquired to obtain a main substrate. Techniques for inspecting uneven coating on the surface have been proposed.

In Patent Document 2, in an image showing a shadow mask, integrated data is obtained by integrating the values of pixels arranged in the other direction at each position in one direction among the arrangement directions of pixels orthogonal to each other. Is determined based on the normalized data obtained by dividing the integrated data by the corresponding value of the smoothed data obtained by smoothing the integrated data (that is, whether the defect is defective or not). ) Is disclosed. Further, in Patent Document 3, in an image obtained by imaging the corneal endothelium, an average value of pixels arranged in each radial direction around the target pixel specified by a predetermined process is obtained, and the radial direction is represented as a variable. A method for obtaining the contour line of the corneal endothelial cell by differentiating the function of the evaluation value in the radial direction and specifying the radial direction in which the sign of the differential coefficient changes is disclosed.
JP 2006-49630 A JP-A-9-68502 JP-A-6-261864

  By the way, when the resist film is formed, for example, if a minute unnecessary object is present on the substrate just before the resist solution is applied, a streak extending along the centrifugal direction centering on the rotation axis while starting the unnecessary object. Unevenness may occur on the resist film. In this case, even if the integrated data obtained by integrating the pixel values in the pixel arrangement direction is obtained as in the method of Patent Document 2, it is difficult to accurately confirm the presence of the stripe unevenness. Therefore, a new method is required that can accurately confirm the presence of streak unevenness extending in the centrifugal direction around the rotation axis on the film of the substrate.

  The present invention has been made in view of the above problems, and it is possible to accurately and easily detect the presence of streak unevenness extending in the centrifugal direction around the rotation axis on the film of the substrate formed by applying the coating liquid and rotating the substrate. The purpose is to confirm.

  According to the first aspect of the present invention, the coating solution is supplied onto the main surface of the substrate and the substrate is rotated about a rotation axis perpendicular to the main surface so that the streaks on the film are formed on the main surface. An unevenness inspection apparatus for inspecting unevenness, wherein the film of the substrate is imaged by an imaging device, and an imaging unit that acquires a multi-tone target image, and the rotation axis as a starting point on the main surface A plurality of centrifugal directions toward the outside are set, and by integrating the values of the pixels arranged in the direction corresponding to each of the plurality of centrifugal directions in the target image, a plurality of centrifugal directions corresponding to the plurality of centrifugal directions are integrated. An evaluation value acquisition unit for acquiring an evaluation value.

  Invention of Claim 2 is the nonuniformity inspection apparatus of Claim 1, Comprising: The some cyclic | annular area | region centering on the said rotating shaft is set in the said main surface, The said evaluation value acquisition part is, 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.

  A third aspect of the present invention is the unevenness inspection apparatus according to the second aspect, wherein a part of each annular region overlaps with a part of any other annular region in the radial direction.

  According to a fourth aspect of the present invention, in the unevenness inspection apparatus according to the third aspect, another annular region is set across the boundary between two annular regions adjacent to each other.

  A fifth aspect of the present invention is the unevenness inspection apparatus according to any one of the first to fourth aspects, wherein arrangement directions of pixels orthogonal to each other in the target image are orthogonal to each other on the main surface of the substrate. The evaluation value acquisition 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 an orthogonal coordinate system, and from the converted image, Obtain multiple evaluation values.

  The invention according to claim 6 is the unevenness inspection apparatus according to claim 5, wherein the plurality of centrifugal directions are set at a constant pitch angle, and the number of pixels arranged in a long side of the target image is set. When the half is α, the pitch angle is arctan (1 / α) or less.

  A seventh aspect of the present invention is the unevenness inspection apparatus according to any one of the first to sixth aspects, wherein the substrate is a glass substrate for a flat display device.

  According to an eighth aspect of the present invention, the coating solution is supplied onto the main surface of the substrate and the substrate is formed by rotating the substrate about a rotation axis perpendicular to the main surface. A non-uniformity inspection method for inspecting non-uniformity, comprising: a) a step of preparing a multi-tone target image obtained from the film of the substrate; and b) a plurality of outwards starting from the rotation axis on the main surface. The plurality of evaluation values corresponding to the plurality of centrifugal directions are obtained by integrating the values of pixels arranged in the direction corresponding to each of the plurality of centrifugal directions in the target image. And a step of performing.

  According to the present invention, by referring to the evaluation value, it is possible to accurately and easily confirm the presence of streak unevenness extending in the centrifugal direction around the rotation axis on the film of the substrate.

  Further, in the invention of claim 2, it is possible to suppress the influence of the length of the stripe unevenness on the evaluation value, and to easily confirm the presence of the stripe unevenness having high unevenness strength, that is, easily recognized as unevenness. In invention of claim | item 4, presence of a stripe | line | muscle nonuniformity with high nonuniformity intensity | strength can be confirmed accurately.

  In the invention of claim 5, the evaluation value can be easily obtained, and in the invention of claim 6, the converted image can be generated with high accuracy.

  FIG. 1 is a diagram showing a configuration of an unevenness inspection apparatus 1 according to an embodiment of the present invention. The unevenness inspection apparatus 1 acquires an image of a resist film 92 for pattern formation formed on one main surface 91 of a rectangular glass substrate 9 used in a flat display device such as a liquid crystal display device. This is an apparatus for inspecting streaks on the film 92 of the substrate 9 based on images. Here, the film 92 on the substrate 9 is formed by a spin coating method. Specifically, after supplying a resist solution to a stationary substrate, the substrate is centered on a rotation axis perpendicular to the main surface. As a rotating method (so-called static method), or by supplying a resist solution onto a rotating substrate and then increasing the number of rotations of the substrate (so-called dynamic method). That is, the film 92 on the substrate 9 is formed by supplying a resist solution onto the main surface 91 with an external spin coater and rotating the substrate 9 about a rotation axis perpendicular to the main surface 91. The static method and the dynamic method include a central dropping method for supplying a resist solution to the center of the main surface of the substrate. Further, in the static method, the slit nozzle is provided along the main surface of the substrate in addition to the central dropping method. A so-called slit-and-spin method that rotates the substrate after discharging the resist solution in layers while moving relative to the substrate and supplying the resist solution to a rectangular area excluding the outer edge on the main surface. There is also a method.

  As shown in FIG. 1, in the unevenness inspection apparatus 1, the substrate 9 is placed with the main surface 91 (hereinafter referred to as “upper surface 91”) on which the film 92 is formed facing upward (the (+ Z) side in FIG. 1). The stage 2 to be held, the film 92 on the substrate 9 held on the stage 2 is irradiated with light at a predetermined incident angle, and the film 92 on the upper surface 91 of the substrate 9 is irradiated from the light irradiation unit 3. The light receiving unit 4 that receives the light reflected by the light, the moving mechanism 21 that moves the stage 2 relative to the light irradiation unit 3 and the light receiving unit 4, and the control unit of the unevenness inspection apparatus 1 A computer 5 is provided.

  The (+ Z) side surface of the stage 2 is preferably black matte. The moving mechanism 21 has a configuration in which a ball screw (not shown) is connected to a motor 211, and the stage 211 moves along the upper surface 91 of the substrate 9 along the guide 212 by rotating the motor 211 in FIG. Move in the direction.

  The light irradiation unit 3 is a halogen lamp 31 that is a light source that emits white light (that is, light including light of all wavelengths in the visible region) and a circle extending in the Y direction in FIG. 1 perpendicular to the moving direction of the stage 2. A columnar quartz rod 32 and a cylindrical lens 33 extending in the Y direction are provided. In the light irradiation unit 3, a halogen lamp 31 is attached to an end portion on the (+ Y) side of the quartz rod 32, and light incident on the quartz rod 32 from the halogen lamp 31 is linear light extending in the Y direction (that is, The light beam cross-section is converted to light that is long in the Y direction), is emitted from the side surface of the quartz rod 32, and is guided to the upper surface 91 of the substrate 9 through the cylindrical lens 33. In other words, the quartz rod 32 and the cylindrical lens 33 are an optical system that converts the light from the halogen lamp 31 into linear light perpendicular to the moving direction of the stage 2 and guides it to the upper surface 91 of the substrate 9.

  In FIG. 1, the optical path from the light irradiation unit 3 to the substrate 9 is indicated by a one-dot chain line (the same applies to the optical path from the substrate 9 to the light receiving unit 4). A part of the light emitted from the light irradiation unit 3 is reflected on the (+ Z) side upper surface 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 irradiation unit 3, and the light that has not been reflected by the upper surface of the film 92 out of the light from the light irradiation unit 3 passes through the film 92. A part of the light is reflected by the upper surface 91 of the substrate 9 (that is, the lower surface of the film 92). In the unevenness inspection apparatus 1, interference light between the light reflected by the upper surface of the film 92 and the light reflected by the upper surface 91 of the substrate 9 enters the light receiving unit 4 and passes through the filter 43 and the lens 42. Thus, interference light having a predetermined wavelength is guided to the imaging unit 41.

  FIG. 2 is a diagram illustrating a light receiving surface of the imaging unit 41. As shown in FIG. 2, the imaging unit 41 is provided with a line sensor 410 having a plurality of light receiving elements (for example, CCD (Charge Coupled Device)) 411 arranged linearly 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 acquired. Actually, the two-dimensional image of the film 92 on the substrate 9 is acquired by repeatedly acquiring the intensity distribution of the interference light by the line sensor 410 of the imaging unit 41 as the substrate 9 moves in the X direction. .

  As shown in FIG. 3, the computer 5 has a general computer system configuration in which a CPU 51 for performing various arithmetic processes, a ROM 52 for storing basic programs, and a RAM 53 for storing various information are connected to a bus line. The bus line further includes a fixed disk 54 that stores information, a display 55 that is a display unit that displays various types of information, a keyboard 56a that accepts input from an operator, and a mouse 56b (hereinafter collectively referred to as "input unit 56"). .), A reader 57 for reading information from a computer-readable recording medium 8 such as an optical disk, a magnetic disk, a magneto-optical disk, and a communication unit 58 connected to other components of the unevenness inspection apparatus 1 As appropriate, they are connected via interfaces (I / F) 59a, 59b, 59c.

  The computer 5 reads the program 541 from the recording medium 8 via the reader 57 in advance and stores it in the fixed disk 54. Then, when the program 541 is copied to the RAM 53 and the CPU 51 executes arithmetic processing according to the program in the RAM 53 (that is, when the computer executes the program), the computer 5 inspects the stripe unevenness on the substrate 9. The operation as a calculation part is performed.

  FIG. 4 is a block diagram illustrating a functional configuration realized by the CPU 51, the ROM 52, the RAM 53, the fixed disk 54, and the like when the CPU 51 operates according to the program 541. In FIG. 4, an image processing unit 61, an evaluation value acquisition unit 62, and a determination unit 63 in the calculation unit 6 show functions realized by the CPU 51 and the like. Note that these functions may be realized by a dedicated electrical circuit, or a dedicated electrical circuit may be partially used.

  Next, the flow of inspection for streaks by the unevenness inspection apparatus 1 will be described. FIG. 5 is a diagram showing a flow of processing in which the unevenness inspection apparatus 1 inspects streaks on the film 92 of the substrate 9. In the unevenness inspection apparatus 1, first, the substrate 9 on which the film 92 is formed on the upper surface 91 by applying the resist solution and rotating the substrate 9 is placed on the stage 2 positioned at the inspection start position indicated by the solid line in FIG. After being held, the movement of the stage 2 in the (+ X) direction is started. Subsequently, linear light emitted from the light irradiation unit 3 and incident on the upper surface 91 of the substrate 9 at a predetermined incident angle is converted into a linear irradiation region on the upper surface 91 (hereinafter referred to as “linear irradiation region”). The linear irradiation area moves relative to the substrate 9. The light from the light irradiation unit 3 is reflected by the upper surface 91 of the substrate 9, the interference light is guided to the imaging unit 41 and received by the line sensor 410, and the intensity of the interference light in the linear irradiation region on the substrate 9. Distribution is acquired. The output from each light receiving element 411 of the line sensor 410 is sent to the computer 5 while being converted into a value (pixel value) of, for example, 8 bits (of course, other than 8 bits) based on a predetermined conversion formula. .

  In the unevenness inspection apparatus 1, while the stage 2 is moving in the (+ X) direction, the acquisition of the interference light intensity distribution in the imaging unit 41 and the output of the pixel value to the computer 5 are synchronized with the movement of the stage 2. Repeated. When the stage 2 moves to the inspection end position, the movement of the stage 2 by the moving mechanism 21 is stopped, and irradiation of illumination light is also stopped. As described above, the imaging unit 41 captures the entire film 92 on the substrate 9 and captures a multi-gradation two-dimensional image (an image to be processed in the calculation unit 6 as will be described later. Is acquired and input to the calculation unit 6 of the computer 5 for preparation (step S11).

Subsequently, the image processing unit 61 of the calculation unit 6 compresses the target image. Here, the coordinates in the target image (X, Y) to represent the pixel value of the pixel and F _XY located, the target image s _a pixel × s _a pixel range compressed generated images as a unit of (compression In the later target image), the pixel value A _xy of the pixel of interest located at the coordinates (x, y) is obtained by _Equation 1.

Since in this embodiment s _a is 4 (pixels), S / N ratio of the target image after compression by the computation of the number 1 is improved to four times the original target image. Subsequently, low-pass filter processing is performed on the target image after compression, and a smoothed image (target image after low-pass filter processing) in which the influence of high-frequency noise is suppressed is generated from the target image after compression. The window for determining the calculation range of the low-pass filter processing is a square having one side length of (2s ₁ +1) pixels, and the pixel of the target pixel located at the 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 near the target pixel.

Thereafter, a high-pass filter process is performed on the target image after the low-pass filter process, and an image obtained by removing low-frequency density fluctuation that hinders a contrast enhancement process described later from the target image after the low-pass filter process (the high-pass filter process) Later target image) is generated. Here, the pixel value H ¹ _xy of the target pixel located at the coordinates (x, y) is expressed by using the pixel value L (see Formula 2) in the target image after the low-pass filter processing of each pixel near the target pixel. 3 is required.

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

In the image processing unit 61, contrast enhancement processing is further performed on the target image after the high-pass filter processing to generate a target image after the enhancement processing (step S13). The pixel value E _xy of the target pixel located at the coordinates (x, y) in the target image after the enhancement process is the pixel value H ¹ _xy of the target pixel in the target image after the high-pass filter process, the contrast coefficient r _c , and the background. Using the value b, it is obtained by Equation 4. In this embodiment, _{r c} is the 0.01,0.02,0.05 or 0.1, b is a 127.

  FIG. 6 is a diagram illustrating the target image 71 after the enhancement process. Here, the target image 71 after enhancement processing (hereinafter simply referred to as “target image 71”) is an image of 256 gradations, and the average density (that is, the average value of the pixel values) of the target image 71 is about 127. It has become. On the film 92 of the substrate 9 from which the target image 71 has been acquired, streak unevenness (starting from the following process) that extends from the rotation axis in the direction in which centrifugal force acts when the substrate 9 rotates. ) In the target image 71 of FIG. 6, the high density (black) streak area and the low density (white) streak area are in the center (as described later, the substrate 9 However, in practice, streak irregularities that extend in the direction in which the centrifugal force acts start from a position other than the rotation axis on the film of the substrate. In some cases.

  Subsequently, the converted image generation unit 621 of the evaluation value acquisition unit 62 corresponds to the rotation axis of the substrate 9 when forming the film 92 in the target image 71 (hereinafter simply referred to as “rotation axis of the substrate 9”). A converted image is generated by converting the polar coordinate system centered on the position to the orthogonal coordinate system (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 referred to as “center position”). ) Coordinates (cx, cy) are specified. Here, since the target image 71 is acquired around the rotation axis J1 of the substrate 9, as shown in FIG. 6, the center of the target image 71 is set as the center position C1. Subsequently, a distance (hereinafter referred to as “maximum length”) between the position farthest from the center position C1 and the center position C1 in the target image 71 is obtained. As described above, since the center position C1 is the center of the target image 71, the maximum length is equal to half the diagonal length of the target image 71, and the length (pixels) of the target image 71 in the x and y directions. The maximum length K _max is obtained from _Equation 5 where x is x ₁ and y ₁ , respectively.

Further, the converted image generation unit 621 obtains a plurality of radial directions in the target image 71 that start from the center position C1 and go outward. Here, the plurality of radial set at a constant pitch angle, the pitch angle P [degrees], the half of the number of pixels y ₁ arranged in the y direction along the long side of the target image 71 alpha, arctan ( 1 / α). 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 generation unit 621, for example, the zeroth radial direction (hereinafter referred to as “reference dynamics”) that is based on the radial direction indicating the (+ x) direction (indicated by an arrow with a symbol D0 in FIG. 6). By defining as “radial direction”), the m-th (m is greater than or equal to 0 and (β−1) among the plurality of radial directions set in order by the pitch angle P with the counterclockwise direction being positive. angular position theta _m with respect to the reference radial an integer) in the radial direction (. which indicated by an arrow Dm C. in FIG. 6) is obtained as (m × P).

  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 the pixels orthogonal to each other in the target image 71 is on the upper surface 91 of the substrate 9. Therefore, on the upper surface 91 of the substrate 9, a plurality of centrifugal directions toward the outside starting from the rotation axis J1 correspond to a plurality of radial directions in the target image 71, respectively. The pitch angles in the centrifugal direction are also values obtained by arctan (1 / α), where α is the half of the number of pixels arranged on the long side of the target image 71. In FIG. 7, two centrifugal directions are indicated by arrows D0 and Dm having the same reference numerals as the corresponding radial directions in FIG.

In this way, when a plurality of radial directions in the target image 71 shown in FIG. 6 are set, a plurality of angular positions θ _{m in} the radial direction around the center position C1 in the target image 71 and the respective radial directions are set. A polar coordinate system defined by a distance n from the center position C1 along the radial direction (where n is an integer not less than 0 and not more than the maximum length K _max ) is expressed by a distance n along the radial direction and an angular position θ. A converted image converted to an orthogonal coordinate system defined by a radial direction number m corresponding to _m is obtained. Here, the value (pixel value) of the pixel located at the coordinate (n, m) in the converted image is the coordinate (x, y) in the target image 71 obtained by substituting the value of n, m into Equation 6. The value of the pixel located at. However, cx and cy are the x coordinate and the y coordinate of the center position C1 in the target image 71, respectively, and P is the pitch angle in the radial direction. Further, when the coordinate (x, y) obtained by the equation 6 with respect to a certain coordinate (n, m) in the converted image indicates the outside of the target image 71, the coordinate (n, m) is located. An intermediate value (background value) 127 of the target image 71 is given to the pixels of the converted image.

  FIG. 8 is a diagram showing a converted image 72 generated from the target image 71 of FIG. In the converted image 72 of FIG. 8, the vertical direction and the horizontal direction correspond to the radial direction number m and the distance n along the radial direction, respectively. When the converted image 72 is generated, in the evaluation value acquisition unit 62, as shown in FIG. 9, each of the converted images 72 extends over the entire vertical direction, and the width in the horizontal direction is constant at W. A plurality of rectangular areas 73 (in FIG. 9, the plurality of rectangular areas 73 arranged in the horizontal direction are alternately indicated by a solid rectangle and a dashed rectangle) are half the width W ( W / 2) is set in the horizontal direction. Therefore, the other rectangular regions 73 (shown with parallel diagonal lines in FIG. 9) straddle the boundary between two adjacent rectangular regions 73 (indicated by broken lines 73a in FIG. 9) that are in contact with each other. ) Is set, and the width in the horizontal direction of the area where each rectangular area 73 overlaps with the other rectangular area 73 is half the width of the rectangular area 73 (W / 2).

  When a plurality of rectangular areas 73 are set in the converted image 72, a value obtained by integrating the values of pixels arranged in the horizontal direction in each rectangular area 73 is divided by the number of the pixels (that is, an average value is obtained). Thus, as shown in FIG. 10, a plurality of evaluation values for a plurality of radial directions in each rectangular region 73 are acquired (step S15). In FIG. 10, the vertical axis indicates the evaluation value, and the horizontal axis indicates the radial direction number.

  Here, the horizontal direction in the converted image 72 corresponds to the distance in the radial direction centered on the rotation axis J1 on the upper surface 91 of the substrate 9 (that is, the direction away from the rotation axis J1). As shown in FIG. 7, the plurality of rectangular regions 73 occupying the range of the width W at different positions are a plurality of annular regions occupying the range of the width W at different positions in the radial direction on the upper surface 91 of the substrate 9. 74 (however, only a part of the annular region 74 is shown in FIG. 7). More specifically, similarly to the rectangular region 73 in the converted image 72, another annular region 74 (crossing the boundary between two annular regions 74 adjacent to each other while being in contact with each other (region surrounded by a broken line in FIG. 7) ( In FIG. 7, there are regions with parallel diagonal lines), and a part of each annular region 74 overlaps a part of any other annular region 74 in the radial direction. Therefore, the above processing for accumulating the values of the pixels arranged in the horizontal direction in each rectangular area 73 in the converted image 72 to obtain the evaluation value is performed in each annular area along each of the plurality of radial directions in the target image 71. This is equivalent to obtaining an evaluation value by integrating the values of pixels existing in a range corresponding to the entire width of 74.

  When a plurality of evaluation values in each rectangular area 73 are acquired, the determination unit 63 compares each evaluation value with 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. If any of the evaluation values is equal to or higher than the upper threshold value or equal to or lower than the lower threshold value, the stripe unevenness that extends along the centrifugal direction on the film 92 of the substrate 9 and should be a defect is present. It is determined that it exists (step S16). For example, in the graph shown in FIG. 10, the radial direction of the number whose evaluation value is equal to or higher than the upper threshold value T1 or lower threshold value T2 corresponds to the stripe unevenness that should be a defect. As described above, in the determination unit 63, the absolute value of the difference between the density of the corresponding pixel group in the target image 71 and the background value (average density) of the target image 71 among the streaks on the film 92 of the substrate 9. Hereinafter, streak unevenness having a large streak) is detected as a streak unevenness defect, and the fact that the streak unevenness defect exists on the film 92 of the substrate 9 is displayed on the display 55 and reported to the operator. Note that the presence of streaks (defects) extending along the centrifugal direction on the substrate 9 is confirmed by the computer 5 displaying on the display 55 a graph (see FIG. 10) showing a plurality of evaluation values corresponding to a plurality of centrifugal directions. For example, it may be performed by an operator.

  Further, if necessary, from the rectangular region 73 from which the evaluation value equal to or higher than the upper threshold value or lower than the lower threshold value is acquired and the radial region, the annular region 74 on the substrate 9 corresponding to the rectangular region 73, and The centrifugal direction on the substrate 9 corresponding to the radial direction is specified, and the position on the substrate 9 where the nonuniformity defect (at least a part thereof) exists is acquired. The information indicating the position is used to specify the cause of the occurrence of a nonuniformity defect (for example, specify the cause of the pattern shape already formed on the substrate 9 before application of the resist solution), or the subsequent It is used for the management of the effect of the non-uniformity defect on the processing and the final product.

  As described above, in the unevenness inspection apparatus 1 in FIG. 1, in the target image 71 obtained from the film 92 on the substrate 9 formed by applying the resist solution and rotating the substrate, A plurality of evaluation values corresponding to a plurality of centrifugal directions are acquired by performing a process of integrating the values of pixels arranged in the direction corresponding to each of the plurality of centrifugal directions to be set. As a result, the determination unit 63 (or the operator) refers to the evaluation value to accurately detect the presence of streak unevenness extending along the centrifugal direction about the rotation axis J1 on the film 92 of the substrate 9. It can be easily confirmed.

  In the unevenness inspection apparatus 1, a plurality of annular regions 74 centering on the rotation axis J <b> 1 are set on the upper surface 91 of the substrate 9. Here, if the evaluation value is acquired by accumulating the values of all the pixels arranged along each radial direction in the target image 71, the evaluation value of the non-uniformity strength is low and the unevenness strength is high. In addition, the short streak unevenness evaluation value becomes almost the same value, and it may be difficult to detect only streak unevenness with high unevenness intensity. On the other hand, the evaluation value acquisition unit 62 obtains an evaluation value by integrating the values of pixels existing in a range corresponding to the entire width of each annular region 74 along the radial direction in the target image 71. By suppressing the influence of the length of the stripe unevenness on the evaluation value, it becomes possible to easily confirm only the presence of the stripe unevenness having a high unevenness intensity. Further, since another annular region 74 is set across the boundary between the two annular regions 74 adjacent to each other, it is shorter than the width of the annular region 74 while straddling the two adjacent annular regions 74. Even when unevenness exists, the presence of such unevenness can be confirmed with high accuracy. In the above description, the unevenness intensity is based only on the density in the image. However, since the unevenness intensity generally indicates the ease of recognition as unevenness, the length of the unevenness of the stripe is also uneven. It can also be added as an element of strength.

  In the unevenness inspection apparatus 1, as shown in FIG. 11, the imaging unit 41 having the line sensor 410 is disposed above the upper surface 91 of the substrate 9, and the line sensor 410 is located with respect to the substrate 9 around the rotation axis J <b> 1 of the substrate 9. The target image may be acquired by performing imaging while rotating 360 degrees. In this case, the plurality of pixels in each row of the target image respectively indicate 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, and the evaluation value is acquired. In the unit, it is possible to easily obtain a plurality of evaluation values corresponding to a plurality of centrifugal directions by accumulating the values of the pixels arranged in the row direction at each position in the column direction of the target image.

  Further, immediately after the film 92 is formed on the substrate 9 by the spin coater, a line sensor is disposed above the substrate 9 placed on the spin coater stage, and the target image is acquired by rotating the stage. May be. As described above, when the target image is acquired, the rotation of the line sensor with respect to the film 92 on the substrate 9 may be relative, and the function of the unevenness inspection apparatus 1 may be combined with the spin coater.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  For example, if the pitch angle in the plurality of centrifugal directions is less than arctan (1 / α), where α is half of the number of pixels arranged on the long side of the target image 71, other pitch angles may be adopted. Good. Thereby, a conversion image can be generated with high accuracy.

  Further, in the above embodiment, the other annular regions 74 are set across the boundary between the two adjacent annular regions 74 in contact with each other on the upper surface 91 of the substrate 9. Another annular region 74 may be set across the boundary between the two annular regions, and even in this case, it is possible to accurately confirm the presence of the stripe unevenness located only in the vicinity of the boundary between the two annular regions. It becomes possible. In addition, the plurality of annular regions may have different widths with respect to the radial direction centered on the rotation axis J1, for example, the plurality of annular regions may be set so as to be wider as they are arranged on the outer side. Good.

  The evaluation value acquisition unit 62 generates a converted image 72 by extracting pixel values along each of the plurality of radial directions in the target image 71, thereby generating a plurality of corresponding centrifugal directions from the converted image 72. Although the evaluation values can be easily obtained, it is also possible to directly obtain a plurality of evaluation values corresponding to a plurality of centrifugal directions from the target image 71 without generating the converted image 72.

  Further, if the values of the pixels arranged in the direction corresponding to each centrifugal direction in the target image 71 or the converted image 72 are accumulated, the value itself obtained by integrating the pixel values or the weight corresponding to the position of each pixel. A weighted average value or the like obtained by assigning may be used as the evaluation value.

  In the unevenness inspection apparatus 1 in FIG. 1, the target image is acquired by linearly moving the substrate 9 with respect to the line sensor 410 that is a one-dimensional imaging device, but the line sensor 410 is linearly moved with respect to the substrate 9. Thus, the target image may be acquired. That is, the linear movement of the line sensor 410 with respect to the substrate 9 may be relative. It is also possible to acquire a target image by imaging the film 92 of the substrate 9 with a two-dimensional imaging device in which light receiving elements are two-dimensionally arranged.

  If the film on the substrate 9 is formed by spin coating, a coating solution other than the resist solution is applied onto the main surface of the substrate 9 when the substrate 9 is rotated or immediately before the rotation of the substrate 9 is started. It may be formed by supplying. In addition, the unevenness inspection apparatus 1 is particularly suitable for inspecting streaks on a film formed on a glass substrate for a flat display device, but by applying a coating liquid and rotating the substrate on another substrate such as a semiconductor substrate. It is also possible to use it for inspection of streaks on the formed film.

It is a figure which shows the structure of a nonuniformity inspection apparatus. It is a figure which shows the light-receiving surface of an imaging part. It is a figure which shows the structure of a computer. It is a block diagram which shows the function structure which a computer implement | achieves. It is a figure which shows the flow of the process which a nonuniformity inspection apparatus test | inspects the stripe nonuniformity on the film | membrane of a board | substrate. It is a figure which shows a target image. It is a figure for demonstrating the some centrifugal direction set on a board | substrate. It is a figure which shows a conversion image. It is a figure which shows the rectangular area | region in a target image. It is a figure which shows several evaluation value with respect to several radial direction. It is a figure for demonstrating the other operation example in which an imaging part acquires a target image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Unevenness inspection apparatus 9 Board | substrate 41 Image pick-up part 62 Evaluation value acquisition part 71 Target image 72 Conversion image 74 Annular area | region 91 Upper surface 92 Film | membrane 410 Line sensor J1 Rotation axis P Pitch angle S11, S15

Claims (8)

An unevenness inspection apparatus that inspects streaks on a 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. And
An imaging unit that obtains a multi-tone target image by imaging the film of the substrate with an imaging device;
A plurality of centrifugal directions are set on the main surface, starting from the rotation axis and directed outward. By integrating the values of pixels arranged in the direction corresponding to each of the plurality of centrifugal directions in the target image. An evaluation value acquisition unit that acquires a plurality of evaluation values corresponding to the plurality of centrifugal directions;
A nonuniformity inspection apparatus comprising: The unevenness inspection apparatus according to claim 1,
A plurality of annular regions around the rotation axis are set on the main surface,
The evaluation value acquisition unit integrates 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 in the target image. A non-uniformity inspection apparatus characterized by obtaining The unevenness inspection apparatus according to claim 2,
A portion of each annular region overlaps with a portion of any other annular region in the radial direction. The unevenness inspection apparatus according to claim 3,
An unevenness inspection apparatus, wherein another annular region is set across a boundary between two annular regions adjacent to each other. The unevenness inspection apparatus according to any one of claims 1 to 4,
The arrangement direction of the pixels orthogonal to each other in the target image corresponds to two directions orthogonal to each other on the main surface of the substrate,
The evaluation value acquisition 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 an orthogonal coordinate system, and obtains the plurality of evaluation values from the converted image. A characteristic unevenness inspection device. The unevenness inspection apparatus according to claim 5,
The plurality of centrifugal directions are set at a constant pitch angle, and the pitch angle is arctan (1 / α) or less, where α is half of the number of pixels arranged on the long side of the target image. An unevenness inspection device. The unevenness inspection apparatus according to any one of claims 1 to 6,
The unevenness inspection apparatus, wherein the substrate is a glass substrate for a flat display device. A method for inspecting unevenness on a 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. And
a) preparing a multi-tone target image obtained from the film of the substrate;
b) A plurality of centrifugal directions are set on the main surface starting from the rotation axis and directed outward, and the values of pixels arranged in directions corresponding to the plurality of centrifugal directions in the target image are integrated. A step of obtaining a plurality of evaluation values corresponding to the plurality of centrifugal directions;
An unevenness inspection method comprising:

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