JP2006275609A - Irregularity inspection device and irregularity inspection method for cyclic pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an irregularity inspection device of high detection accuracy for a cyclic pattern and an irregularity inspection method. <P>SOLUTION: This irregularity inspection device comprises: four light sources for illuminating the cyclic pattern on a substrate on an XY stage with obliquely transmitted light; an imaging means for imaging diffracted light on the illuminated cyclic pattern; a movement means 1 for severally moving each of the light sources relative to the substrate in a two-dimensional planar visual field, a posture changing means for changing the directions of the light sources so that the illumination of the transmitted light from the light sources falls on the cyclic pattern; and a quasi-defect removal means 40 for dividing an imaging object area on the substrate into at least two areas, adjusting a relative positional relation between the XY stage and the light sources while adjusting the light amount of the light sources to adjust the luminance level of each division area, severally imaging each division area by the imaging means to severally capture division image data obtained by the imaging, compositing an image by together joining captured division images, and preventing quasi-defects from being determined as defects in determining stripe-like irregularity by using a composited image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for inspecting pattern unevenness in a product having a periodic pattern, and is formed periodically on a substrate such as an aperture grill, a photomask, or a color filter used for a cathode ray tube of a color television. The present invention relates to a periodic pattern unevenness inspection apparatus and unevenness inspection method capable of detecting stripe-shaped unevenness generated in a pattern with high accuracy.

  For unevenness inspection of periodic patterns (hereinafter referred to as PM patterns) of substrates such as aperture grills, photomasks, and color filters used in color television CRTs, a transmittance image is captured using coaxial transmission illumination or planar illumination. Then, the unevenness portion and the normal portion are visually recognized by comparing the intensity (brightness) of light in each image. For this reason, in the PM pattern, the difference in light intensity between the uneven portion and the normal portion is originally small, that is, by devising an intensity difference processing method for images with low contrast, the difference is expanded and the uneven portion is extracted. , Have been inspected.

  However, in the imaging of black matrix unevenness of a lattice-like periodic pattern, especially unevenness of a black matrix with a large opening, improvement in contrast between the uneven portion and the normal portion cannot be expected, and even if the intensity difference processing is devised In the inspection in the case of an image having a low contrast of the original image, there is a problem that only an inspection ability lower than the visual sensory inspection method can be achieved. The periodic pattern refers to an aggregate of slit patterns having a constant interval (hereinafter referred to as a pitch). For example, a striped periodic pattern in which one pattern is arranged at a predetermined pitch, or an opening. These patterns are a matrix-like periodic pattern in which these patterns are arranged at a predetermined pitch.

  On the other hand, due to the increase in the number of electronic components with fine display and bright screen, the PM pattern tends to be miniaturized or the aperture ratio is increased. In the future, there will be a need for an inspection method and apparatus for periodic pattern irregularity inspection for a black matrix having a finer shape and a larger opening. That is, the conventional output with only the intensity (brightness) of the light intensity (brightness) based on the amplitude of the light is a limit, and unevenness cannot be clearly detected.

Therefore, an attempt has been made to apply a technique such as a projection method, which has a proven track record in coating color unevenness inspection, to the PM pattern unevenness inspection technology. For example, Patent Document 1 proposes a method of enhancing and detecting defects by image processing using a Laplacian filter.
Japanese Patent Laid-Open No. 9-264730

  However, since the above-described conventional technique is processing on a two-dimensional image, noise components are likely to remain in the image, and it is difficult to say that this is an optimal inspection method. In particular, as a method for inspecting streaky irregularities of PM patterns, since the defect level is very small, it is very difficult to detect the irregularity of the target limit sample, and the current performance has low detection accuracy of defects. It is insufficient. Therefore, there is a demand for a PM pattern unevenness inspection method with higher detection accuracy than the conventional method.

  Further, in the conventional method, when determining streak-like unevenness of the PM pattern, a false defect caused by the light diffraction phenomenon is easily erroneously determined as streak-like unevenness, and it is difficult to say that the inspection accuracy is high.

  SUMMARY An advantage of some aspects of the invention is to provide a periodic pattern unevenness inspection apparatus and unevenness inspection method having high detection accuracy.

  A periodic pattern unevenness inspection apparatus according to the present invention is a periodic pattern unevenness inspection apparatus for inspecting streaky unevenness that occurs in a periodic pattern on a rectangular substrate, and the substrate is substantially horizontal. An XY stage (20) provided with a moving mechanism (22, 23) for holding and moving the substrate in the X-axis direction and the Y-axis direction within a two-dimensional planar field of view, and a periodic pattern of the substrate on the XY stage 4 light sources (11A-11D) that individually illuminate obliquely transmitted light, and the periodic pattern that is disposed on the opposite side of the light source across the XY stage and illuminated obliquely by the light source Imaging means (31) for imaging the diffracted light in the light source, moving means (13) for individually moving the light sources with respect to the substrate on the XY stage within a two-dimensional plane field of view, and the light source by the moving means Moved Attitude changing means (12) for changing the orientation of the light source in conjunction with the moving means so that the periodic pattern to be inspected is illuminated with obliquely transmitted light from the light source when The area to be imaged on the substrate is divided into at least two areas, the relative positional relationship between the XY stage and the light source is adjusted, and the light intensity of each of the light sources is adjusted individually to adjust the luminance of each of the divided areas. The level is adjusted, each divided area is imaged by the imaging means with the adjusted luminance level, the captured divided image data is captured, the captured divided images are joined together, and the combined images are used to create a stripe. And a pseudo defect removing means (40) that does not determine the pseudo defect as a defect when determining the unevenness.

  The pseudo defect removing means divides the imaging target area on the substrate into two areas, adjusts the light amount of the first light source starting from the past light amount, and uses the adjusted light amount to adjust the first light source. The first area of the divided area is imaged, the image data is captured, the light quantity of the second light source is adjusted starting from the light quantity of the first light source at the time of imaging, and the first light quantity is adjusted with the adjusted light quantity. The other light source area of the divided area is imaged by the two light sources, the image data is captured, the image data of the one side area and the image data of the other side are joined together, and the combined image is synthesized. It can be used to determine streak-like unevenness.

  A periodic pattern unevenness inspection method according to the present invention is a periodic pattern unevenness inspection method for inspecting streaky unevenness generated in a periodic pattern on a rectangular substrate, and (a) an imaging target on the substrate (B) dividing the area into at least two areas, adjusting the relative positional relationship between the substrate and the light source, and adjusting the luminance level of each of the divided areas by individually adjusting the light quantity of the light source; A step of capturing each divided area with the adjusted luminance level, a step of (c) capturing each of the captured divided image data, and (d) combining the captured divided images by joining together, and using the combined image And a pseudo defect removal step in which the pseudo defect is not determined as a defect when the stripe-shaped unevenness is determined.

  In the above method, in the step (a), the imaging target area on the substrate is divided into two areas, the light amount of the first light source is adjusted starting from the past light amount, and the step (b) One area of the divided area is imaged by the first light source with the adjusted light quantity, and the image data is captured in the step (c), starting from the light quantity of the first light source at the time of imaging. In step (b), the second light source is used to image the other area of the divided area, and in step (c), the image data is captured. In the step (d), the image data of the one side area and the image data of the other side are connected to each other and synthesized, and the stripe-shaped unevenness can be determined using the synthesized image.

  In the present invention, a pseudo defect removal function is added in the determination condition that is the classification of the recipe. When the inspection is performed with the pseudo defect removal function enabled, except for the pseudo defect removal process, the determination / review of other processes uses the image of only one light source for determination / display. On the other hand, when the inspection is performed with the pseudo defect removal function disabled, it is also possible to perform measurement by simultaneously lighting a plurality of light sources as before, and determination and display are performed using an image at the time of simultaneously lighting a plurality of light sources.

  According to the present invention, the amount of light is adjusted to illuminate the divided area, the captured image is combined, and a plurality of captured images are combined and determined and displayed with the luminance level of the pseudo defect lowered in the combined image. When determining whether or not the defect is a uneven shape defect, the pseudo defect is easily removed, and the inspection accuracy is increased.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  The periodic pattern non-uniformity inspection apparatus of the present invention is based on the optical condition 4-axis setting function, the individual setting / storing function for each axis, the reference condition / reference described in the specification of the Japanese Patent Application No. 2005-18325. It has all of the condition setting function, the illumination center position adjustment function, etc. In addition to these basic functions, a pseudo defect removal function is provided as an additional function within the determination condition.

  As shown in FIG. 1, the unevenness inspection apparatus includes an oblique transmission illumination unit 10, an XY stage unit 20, an imaging unit 30, and a processing unit 40. The processing unit 40 has a function of emphasizing the image captured by the imaging unit 30, determining whether the image is uneven, and displaying the unevenness so that the operator can easily recognize the emphasized image. Yes.

  The oblique transmission illumination unit 10 includes four lamps 11A to 11D. Each of the lamps 11A to 11D is movably supported on the linear guide 14 by a swing mechanism 12 as a posture changing unit and a linear slider 13 as a moving unit. The linear guide 14 is composed of two X guides and Y guides which are arranged so as to be orthogonal to each other within a plane field of view. Of the two X guides, the first ramp 11A is provided so as to be able to slide in the X direction, and on the other side, the second ramp 11B is provided so as to be capable of sliding in the X direction. In addition, the third lamp 11C is provided on one of the two Y guides so as to be slidable in the Y direction, and the fourth lamp 11D is provided on the other side so as to be slidable in the Y direction. The linear slider 13 is drivably engaged with the linear guide 14 and supports the lamps 11 </ b> A to 11 </ b> D via the swing mechanism 12. Further, each of the lamps 11A to 11D is provided with means for switching on and off (changing the point light source) so that the distance from the inspection target substrate, the incident angle of illumination light, and the direction can be switched. .

  The head swing mechanism 12 includes a micro motor, a horizontal shaft connected to the motor rotation drive shaft, and a holder that rotates around the horizontal shaft together with the lamps 11A to 11D. Each of the lamps 11A to 11D swings as shown in FIG. As a result, the light projection angle θ of the light from the lamps 11A to 11D changes variously, and illumination from various angles and directions is possible. Each of the lamps 11A to 11D can be detachably mounted with an optical filter that transmits light having a desired wavelength. The optical filter is prepared in one-to-one correspondence with the wavelength of light, and is changed to a desired optical filter in accordance with changes in customer specifications and inspection recipes.

  For the lamps 11A to 11D, a linear light source including a parallel optical system including a telecentric lens is used. This type of light source has uneven brightness and uneven illuminance, and if the illumination intensity is high, the captured image may be affected. In the inspection apparatus of the present embodiment, an illumination center position adjustment function is added as a measure for preventing luminance unevenness and illuminance unevenness.

  In the XY stage unit 20, a mask 50 as an inspection target substrate is placed and held at a predetermined position on the XY stage 21. The XY stage unit 20 has a measurement function, recognizes the position, and superimposes the optical axis of the apparatus on the inspection start position of the mask 50. The XY stage 21 is supported by an X drive mechanism 22 and a Y drive mechanism so as to be movable in the X direction and the Y direction in a horizontal plane.

  The imaging unit 30 includes an imaging-side parallel optical system 31 parallel to the optical axis, and shares functions such as a means for capturing an image, for example, a camera with a CCD, image data conversion, data storage and transmission. The imaging side parallel optical system 31 includes an optical system or a projection optical system that can image the inspection target pattern 51 at a desired magnification (including enlargement or reduction, and equal magnification).

  The processing unit 40 comprehensively manages the imaging unit 30, the XY stage unit 20, and the transmitted illumination unit 10, and also comprehensively manages means for sequentially processing the inspection process of the periodic pattern unevenness. The processing unit 40 includes a personal computer main body 41 having a CPU and a memory, a display unit 42 including a liquid crystal display and a CRT display, and a keyboard input unit 43. The processing unit 40 receives image data picked up from the image pickup unit 30, extracts and compares the features of the image according to a predetermined data processing procedure, calculates the difference, and determines pass / fail.

  Next, the outline of the control system of the inspection apparatus will be described with reference to FIG.

  The inspection apparatus of the present invention is constituted by five subsystems 40a to 40e. The data input unit 40a includes a sensor unit 411, an illumination unit 412, a position fixing unit 413, and a position control unit 414. The sensor unit 411 includes a plurality of sensors such as a position sensor for position detection, a distance sensor for detecting a moving distance (including an encoder and a counter), and a light detection sensor for detecting luminance. The data processing unit 40b includes an image processing unit 415 that processes imaging data input from the sensor unit 411 of the data input unit 40a, and a data management unit 416 that manages the processed data. Detection signals are sent to the image processing unit 415 from each sensor of the sensor unit 411 as needed. The image processing unit 415 may be a part of the function of the personal computer 41 of the processing unit 40 or may be a processing unit independent of the personal computer 41.

  The illumination unit 412 controls the lamps 11A to 11D. The position fixing unit 413 controls the XY stage unit 20. The position control unit 414 individually controls the swing mechanism 12 and the linear slider 13 of the lamps 11A to 11D.

  The machine interface unit 40c includes a machine interlocking unit 417 that transmits / receives data to / from an external device such as a transport mechanism (not shown) that transports the mask 50 to be inspected, and an automatic supply / discharge unit that transfers the mask. 418. The human interface unit 40e includes an information display unit 42 that displays a processed image processed by the data processing unit 40b, and an interpersonal operation unit 43 that exchanges information with an operator. The system bus 40d is an interface between the human interface unit 40e and the other subsystems 40a to 40c for data transmission / reception.

  Next, the periodic pattern unevenness inspection procedure will be described with reference to FIG.

  The main switch is turned on to start the apparatus in a state where inspection can be started (step S1). Predetermined initial conditions are set by key board input or the like, and the setting operation is terminated when all the initial conditions are obtained (step S2).

  The mask 50 is placed on the XY stage 21, the X drive mechanism 22 and the Y drive mechanism 23 are driven, the mask 50 is moved to the inspection start position together with the XY stage 21, and the periodic pattern 51 to be inspected is captured in the imaging area. (Step S3).

  Next, imaging conditions for the imaging unit 30 are set. That is, the magnification of the camera 31 and the illumination conditions of the oblique transmission illumination unit 10 are set. When these settings are completed, the lamps 11A to 11D are slid and moved, and each lamp is aligned with the imaging area.

  After the alignment, the first lamp 11A is turned on (step S4), the light amount data (actual light amount) obtained at the previous imaging is called from the memory, and the mask that is the subject is started from the called data (actual light amount). The light intensity is automatically adjusted to the optimum light quantity for 50 (step S5).

  It is determined whether dimming is completed (step S6). When the determination result is NO, the dimming operation is repeated until it matches the optimum light amount (steps S6 → S5 → S6).

  When the determination result in step S6 is YES, the light amount of the first lamp 11A is fixed, the inspection target area is imaged under illumination of the light amount, and the image is taken into the personal computer 41 of the processing unit 40 (step S7). . The light amount data (luminance data) when the image is taken under the illumination of the first lamp 11A is recorded in the memory of the processing unit 40 (step S8), and the first lamp 11A is turned off (step S9).

  Next, the second lamp 11B located on the opposite side is turned on (step S10), the light amount data at the time of the previous imaging that was illuminated and imaged from the opposite direction is called from the memory, and the second lamp 11B is called to the called data. The amount of light is set (step S11). This set lamp light quantity does not necessarily have to be set to the counterpart lamp light quantity, but can be corrected to a different value depending on customer specifications and the type of subject. Starting from the light amount in the facing direction, the light amount of the second lamp 11B is automatically adjusted (step S12).

  It is determined whether or not the dimming operation in step S12 is completed (step S13). If the determination result is NO, the dimming operation is repeated until the light intensity matches the optimal light amount (step S13 → S12 → S13).

  When the determination result in step S13 is YES, the light amount of the second lamp 11B is fixed, the inspection target area is imaged under illumination of the light amount, and the image is taken into the personal computer 41 of the processing unit 40 (step S14). . Light amount data (luminance data) at the time of imaging is recorded in the memory of the processing unit 40, and the second lamp 11B is turned off.

  Next, the processing unit 40 combines the two images (a pair of left and right or a pair of upper and lower) captured in the above-described steps S7 and S14 on the screen (step S15). When this image composition processing is performed, pseudo defect removal processing can be performed simultaneously.

  The processing unit 40 or the operator determines the unevenness level (luminance level on the image) for the composite image, and determines and evaluates the presence or absence of streaky unevenness defects based on the determination (step S16). When performing this determination and evaluation, the pseudo defect can be evaluated using only the captured image without the operator displaying a review and displaying the pseudo defect image (sample) on the screen.

  The function of removing pseudo defects is a mode in which automatic measurement / determination is performed after setting in the recipe, and when an image that seems to be a pseudo defect is obtained from the result of measurement using the conventional recipe, only the specified area is processed. It is assumed that there are two modes: a manual mode for displaying a removed image and determining one image. In the automatic mode, conditions preliminarily registered as recipes (light quantity of illumination light, camera magnification, light projection angle, etc.) are read out, and the inspection is automatically executed in accordance therewith.

  When the inspection is performed with the pseudo defect removal function enabled, the determination / display is usually performed with an image subjected to the pseudo defect removal processing, but the image of only one side of the light source can also be determined / displayed. This is because the effect of removing pseudo defects can be actually confirmed using an image of only one-side light source.

  When inspection is performed with the pseudo defect removal function disabled, measurement of simultaneous lighting of a plurality of lamps is possible as before, and determination and display are performed using the captured image itself.

  After the measurement of the imaging area, it is determined whether there is a next imaging area (step S17). When the determination result in step S17 is YES, the mask 50 is moved by the XY stage 21, and the next imaging area is positioned in the camera imaging area (step S18). Then, after the lamp is extinguished (step S18-2), the operations of steps S4 to S17 described above are repeated.

  If the determination in step S17 is NO and it is determined that there is no next imaging area, the imaging data is transferred to the processing unit 40 and image processing is performed in the personal computer 41. Then, the image processing result data is output, and the output result is evaluated. When the evaluation determination is completed, the inspection process is terminated. The mask 50 is lifted from the stage 21, transferred to the transfer arm, and carried out of the chamber. Then, the main switch is turned off to stop the apparatus (step S19).

  After the apparatus is stopped, the entire mask is subjected to overall determination, unevenness counting, and the like, and the mask to be inspected is comprehensively determined (step S20).

  Although it is possible to automatically determine based on a preset unevenness reference value, it is also possible to perform manual determination in which an operator determines the captured image while viewing it on the screen.

  Next, an outline of the generation principle of pseudo defects will be described.

  FIG. 4 is a schematic diagram for explaining the principle of generation of a shadow (ghost) due to multiple reflection (bottom reflection) light. When the inspection light 2 is incident on the mask 50 and illuminates the pattern 51, a real image 34 of the pattern is formed on the image plane 33 of the imaging unit 30. On the other hand, the bottom surface reflected light from the pattern 51 is reflected again (multiple reflection) by the bottom surface of the mask 50, and this multiple reflection image is formed on the image surface 33 to become a shadow (ghost) 35. If this shadow (ghost) 35 appears on the image surface 33 as an image of a pseudo defect, it causes a decrease in the accuracy of the pass / fail judgment of the real image 34. However, in the present invention, since the pseudo defect image is displayed so as to be thinned by the pseudo defect removal function, the inspection accuracy is improved.

  Next, an outline of periodic pattern imaging and unevenness detection will be described.

  In the normal part of the periodic pattern 51, the shape and pitch of the slit part (or opening) are constant, so that they interfere with each other, and strong chamfered light is generated in a certain direction. In the uneven part, the slit part (or opening part). ) Becomes unstable, and diffracted light is generated in various directions with various intensities according to the shape and pitch.

  In the inspection apparatus, the light emitted from the oblique transmission illumination unit 10 is diffracted at the opening of the black matrix mask 50 of the periodic pattern 51, and the diffracted light is captured by the imaging unit 30 as an image. When the incident angle θ is smaller than 90 °, the observation environment is changed, and the difference in the shape and pitch of the slit (or opening) is emphasized, and the difference in the diffracted light is further increased by the illumination that changes the position little by little. To be emphasized.

  The diffracted light diffracted by the mask 50 changes the diffraction angle due to subtle variations in the black matrix. Therefore, the image captured by the imaging unit 30 is an image in which uneven portions due to the black matrix variation are emphasized. Become. Furthermore, by using a parallel optical system for the oblique transmission illumination unit 10 and the imaging unit 30, an image in which the fluctuation of the diffracted light is more accurately emphasized is captured. In addition, by sequentially lighting a plurality of installed lights, it is possible to obtain an optimal image for unevenness having various directions.

  The unevenness image thus captured by the imaging unit 30 is subjected to unevenness extraction processing by the processing unit 40, and determination processing is performed. By displaying the determined unevenness position and level on the processing unit 40 at the same time as the unevenness image, the use for unevenness monitoring is also effective.

  Next, with reference to FIG. 5 to FIG. 7, an outline when the image of streaky irregularities appearing in the periodic pattern is digitized and processed will be described.

  Only the rectangular periodic pattern region of the mask to be inspected is cut out, and as shown in FIG. 6, integrated data 61 is obtained by calculation for the cut out two-dimensional image data. Here, only the integration in the vertical direction (Y-axis direction) in FIG. 5 will be described, but the integration data in the horizontal direction (X-axis direction) can be similarly obtained.

  Next, integrated moving average data 62 for the target point is calculated from the integrated data 61 shown in FIG. Here, the moving average calculation possible range 64 can be changed. However, since the moving average centered on the point of interest is calculated, it is impossible to calculate the integrated moving average data 62 at both end portions 63. Therefore, the end portions 63 that cannot be calculated are moved. The integrated moving average data is calculated using the least square method based on the data at both ends of the average calculable range 64.

  Next, a difference from the integrated moving average data 62 is obtained by the least square method. Thereby, the difference data 71 shown in FIG. 7 is obtained. A predetermined threshold value 72 determined from customer specifications and the like is set. Difference data 71 exceeding the threshold value 72 is determined to be unacceptable, and data not exceeding the threshold value 72 is determined to be acceptable. In this way, the pass / fail determination of the stripe-shaped uneven portion is performed.

  However, both end portions 63 for which the moving average is obtained by the least square method are predicted values by the least square method, and thus there is a risk of causing an error. As a countermeasure, it is possible to set a value 73 different from the threshold value 72 of the moving average calculation range 64 for both end portions 63.

  Next, the setting of illumination conditions will be schematically described with reference to FIG.

  As shown in FIG. 8, when setting the optical condition of each light source based on the optical condition 4-axis setting function, the distance between the light sources / masks is changed variously and light is projected from the lamps 11 </ b> A to 11 </ b> D to the pattern 51. Various angles of light θ1 to θ4 can be changed. Thereby, it becomes possible to project the optimal inspection light onto the pattern according to the shape and type of the pattern 51. The projection angles θ1 to θ4 are preferably in the range of 10 to 80 °. In addition, the distance L from the mask, which is the subject substrate, to the orbit of the light source varies depending on the size of the subject substrate. For example, when the subject substrate is a large color filter, the distance L is preferably about 1 m, and when the subject substrate is a photomask for manufacturing a semiconductor device, the distance L is several hundred mm to several It is desirable to be about mm.

  In addition to the projection angle θ, the distance L, and the light wavelength λ, the light quantity of the light source is added as the illumination condition. That is, in the present invention, when the pseudo defect removal function is enabled, in order to illuminate the divided area of the mask by turning on only the light source on one side, it is necessary to individually set the light amount. The light quantity of the one-side light source is set in consideration of the customer specifications, the periodic pattern specific to the mask, the area of the divided area, the projection angle θ, the distance L, the light wavelength λ, and the like.

  Next, with reference to FIGS. 9 to 19, the image of the example processed according to the present invention and the image of the comparative example processed by the conventional method will be described in comparison.

  FIG. 9 is a photograph showing an inspection image including a pseudo defect when the left area of the mask is imaged by illuminating from the right side of the drawing using only one one-side light source. Pseudo defects appear at the points indicated by arrows in the figure. FIG. 10 is a photograph showing an inspection image including a pseudo defect when the right area of the mask is imaged by illuminating from the left side of the drawing using only the other one-side light source. Pseudo defects appear at the points indicated by arrows in the figure.

  FIG. 11 is a photograph showing an image taken of the left area of the mask, and FIG. 12 is a photograph showing an image taken of the right area of the mask. FIG. 13 is a photograph showing a composite image (example) obtained by combining the left image of FIG. 11 and the right image of FIG. FIG. 14 is an enlarged photograph showing the joint of the composite image in FIG.

  FIG. 15 is a schematic diagram for explaining the joint process of the composite image. When connecting the image A on the left side and the image B on the right side, the respective pixel values are weighted in the form of gradation as shown in the figure in the vicinity of the joint, and are added so that the total weight becomes 100%. The joints will not be noticeable.

  FIG. 16 is a photograph showing an image (comparative example) in which the joint portion is not blurred, and FIG. 17 is an enlarged photograph showing a part of the joint portion of the comparative example image of FIG.

  FIG. 18 is a photograph showing an image (Example) in which the joint portion is blurred by alternate display, and FIG. 19 is an enlarged photograph showing the joint blur portion of the image (Example) in FIG.

  FIG. 20 is a schematic plan view collectively showing the layout of an input screen for recipes and the like and a display screen for camera images and the like.

  As shown in FIG. 20, the operator inputs and changes necessary recipes such as the conditions of the lamps 11 </ b> A to 11 </ b> D and the imaging conditions of the camera while viewing the image displayed on the screen using the input / display panel. be able to. In addition, by performing a necessary input operation using the screen, it is possible to select arbitrary data from the stored history data, display it as a review, and compare it with an actual inspection target image captured by the camera. Thereby, it is possible to easily confirm the inspection image and the inspection result that have already been proven.

  In the apparatus of the present embodiment, the pseudo defect removal function is called using the reference condition / reference condition function to perform the pseudo defect removal processing. The operator determines the unevenness level (luminance level on the image) for the composite image, and determines and evaluates the presence or absence of streaky unevenness defects based on the determined unevenness level. When performing this judgment and evaluation, it is possible to evaluate the pseudo defect using only the captured image without the operator displaying a review and displaying the pseudo defect image (sample) on the screen. In addition, the function of pseudo defect removal is only for the designated area when an image that seems to be a pseudo defect is obtained from the result of measurement with the mode that performs automatic measurement and automatic judgment after setting in the recipe and the previous recipe. It is assumed that there are two modes: a manual mode for displaying a pseudo defect-removed image and determining one image. In the automatic mode, conditions preliminarily registered as recipes (light quantity of illumination light, camera magnification, light projection angle, etc.) are read out, and the inspection is automatically executed in accordance therewith.

  The present invention can be used, for example, to inspect streaky irregularities generated in shadow masks used for color television CRTs, color filters for liquid crystal display panels, photomasks, Brennel lenses, and the like.

1 is a structural block perspective view showing an outline of an inspection apparatus of the present invention. The block diagram which shows the control system of the test | inspection apparatus of this invention. The flowchart which shows the procedure of an inspection method. The schematic diagram for demonstrating the generation | occurrence | production principle of the pseudo defect by multiple reflection (bottom surface reflection) light. The top view which shows typically the mask as a subject. The wave form diagram for demonstrating the calculation procedure when test | inspecting a stripe-shaped nonuniformity. FIG. 6 is another waveform diagram for explaining a calculation procedure when inspecting stripe-like unevenness. The figure which shows an inspection apparatus seeing from the side. The photograph which shows the test | inspection image containing a pseudo defect when it illuminates and images from the right side of a figure. The photograph which shows the test | inspection image containing a pseudo defect when it illuminates and images from the left side of a figure. The photograph which shows the image which imaged the left side area | region of the subject. The photograph which shows the image which imaged the right side area | region of the subject. A photograph showing a combined image obtained by combining left and right images. 14 is an enlarged photograph showing a joint of the composite image in FIG. The schematic diagram for demonstrating the process of the joint of a synthesized image. A photograph showing an image (comparative example) in which there is no blur at the joint. The photograph which expands and shows a part of image (comparative example) of FIG. The photograph which shows the image (Example) which blurred the part of the joint by alternate display. The photograph which expands and shows the connection part blurring part of the image (Example) of FIG. The plane schematic diagram which shows collectively the layout of input screens, such as a recipe, and display screens, such as a camera image.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Diagonal transmission illumination part, 11A-11D ... Light source, 12 ... Attitude change means, 13 ... Movement means, 14 ... Guide path, 20 ... XY stage part, 22 ... X drive mechanism (movement mechanism), 23 ... Y drive mechanism (Moving mechanism), 30 ... imaging unit, 31 ... CCD camera (imaging means), 32 ... camera optical axis (center line), 40 ... processing unit, 41 ... personal computer, 42 ... display screen, 43 ... key board, 50 ... mask (Substrate to be inspected), 52 ... streaky unevenness, 53 ... periodic pattern area, 56 ... imaging area, 58 ... center line (camera optical axis).

Claims (4)

A periodic pattern unevenness inspection apparatus for inspecting streaky unevenness generated in a periodic pattern on a rectangular substrate,
An XY stage having a moving mechanism for holding the substrate substantially horizontally and moving the substrate in the X-axis direction and the Y-axis direction within a two-dimensional planar field of view;
Four light sources that individually illuminate obliquely transmitted light with respect to the periodic pattern of the substrate on the XY stage;
An imaging unit that is disposed on the opposite side of the light source across the XY stage, and that images diffracted light in the periodic pattern illuminated obliquely by the light source;
Moving means for individually moving each of the light sources in a two-dimensional planar field of view relative to the substrate on the XY stage;
When the light source is moved by the moving means, the direction of the light source is changed in conjunction with the moving means so that the periodic pattern to be inspected is illuminated with obliquely transmitted light from the light source. Posture changing means for causing
The imaging target area on the substrate is divided into at least two areas, the relative positional relationship between the XY stage and the light source is adjusted, and the light intensity of each of the light sources is individually adjusted to adjust the luminance level of each of the divided areas. Each divided area is imaged by the imaging means with the adjusted brightness level, the captured divided image data is captured, the captured divided images are connected to each other and synthesized, and a streak shape is formed using the synthesized image. Pseudo defect removal means that does not determine a pseudo defect as a defect when determining unevenness;
A periodic pattern non-uniformity inspection apparatus comprising: The pseudo defect removing unit divides the imaging target area on the substrate into two areas, adjusts the light amount of the first light source starting from the past light amount, and uses the adjusted light amount to adjust the light amount of the first light source. One side area of the divided area is imaged, the image data is captured, the light amount of the second light source is adjusted starting from the light amount of the first light source at the time of imaging, and the second light is adjusted with the adjusted light amount. The other side area of the divided area is imaged with the light source, the image data is captured, the image data of the one side area and the image data of the other side are joined together and synthesized, and the synthesized image is used. The unevenness inspection apparatus according to claim 1, wherein streaky unevenness is determined. A periodic pattern unevenness inspection method for inspecting streaky unevenness generated in a periodic pattern on a rectangular substrate,
(A) The imaging target area on the substrate is divided into at least two areas, the relative positional relationship between the substrate and the light source is adjusted, and the light levels of the light sources are individually adjusted to adjust the luminance levels of the divided areas. Adjusting, and
(B) imaging each of the divided areas with the adjusted luminance level;
(C) capturing each captured divided image data;
And (d) a pseudo-defect removal step in which the captured divided images are connected to each other and synthesized, and a pseudo-defect is not determined as a defect when the streak-like unevenness is determined using the synthesized image. Method for inspecting periodic pattern unevenness. In the step (a), the imaging target area on the substrate is divided into two areas, the light amount of the first light source is adjusted starting from the past light amount, and the adjusted light amount is used in the step (b). One area of the divided area is imaged by the first light source, the image data is captured in the step (c), and the light quantity of the second light source starts from the light quantity of the first light source at the time of the imaging. In the step (b), the other light source area of the divided area is imaged by the second light source with the adjusted light amount, the image data is captured in the step (c), and the step (d) The unevenness inspection method according to claim 3, wherein the image data of the one side area and the image data of the other side are connected to each other and combined, and the stripe-shaped unevenness is determined using the combined image.

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