WO2014156396A1 - High-speed image capture method and high-speed image capture device - Google Patents

High-speed image capture method and high-speed image capture device Download PDF

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Publication number
WO2014156396A1
WO2014156396A1 PCT/JP2014/054103 JP2014054103W WO2014156396A1 WO 2014156396 A1 WO2014156396 A1 WO 2014156396A1 JP 2014054103 W JP2014054103 W JP 2014054103W WO 2014156396 A1 WO2014156396 A1 WO 2014156396A1
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WO
WIPO (PCT)
Prior art keywords
imaging
workpiece
scan rate
image
luminance value
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PCT/JP2014/054103
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French (fr)
Japanese (ja)
Inventor
憲治 大久保
千草 井中
Original Assignee
東レエンジニアリング株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 東レエンジニアリング株式会社 filed Critical 東レエンジニアリング株式会社
Priority to CN201480018385.2A priority Critical patent/CN105103533B/en
Priority to KR1020157030449A priority patent/KR102179261B1/en
Publication of WO2014156396A1 publication Critical patent/WO2014156396A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/8901—Optical details; Scanning details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956—Inspecting patterns on the surface of objects

Definitions

  • the present invention relates to a high-speed imaging method and a high-speed imaging device for imaging a workpiece such as glass, a semiconductor wafer, and an electronic substrate.
  • Patent Document 1 In the process of moving the area image sensor in the scanning direction, a method has been proposed and implemented in which imaging is performed while alternately repeating a predetermined position on the movement locus and a position shifted by 1/2 pixel in the horizontal direction perpendicular to the moving direction.
  • a workpiece to be imaged for example, a semiconductor device or the like is required to have a high throughput in an inspection apparatus or the like by image analysis processing in order to increase the manufacturing quantity per unit time. Therefore, in order to reduce the inspection time spent per substrate, a form has been proposed in which the movement of the holding stage for holding the workpiece is accelerated or a plurality of imaging cameras are arranged.
  • the present invention has been made in view of such circumstances, and it is a main object of the present invention to provide a high-speed imaging method and a high-speed imaging device capable of imaging a workpiece at high speed without being limited by the scan rate of the imaging device. It is aimed.
  • This invention has the following configuration in order to achieve such an object.
  • an embodiment of a high-speed imaging method for imaging a workpiece An imaging process for imaging the workpiece while relatively horizontally moving an imaging unit composed of a plurality of imaging devices equipped with line sensors and a holding table for holding the workpiece, at a predetermined moving speed; An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers, In the imaging process, the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the number of imagers.
  • the divided scan rates are assigned to the image pickup device in order, the image pickup device is shuttered at the start point of each scan rate, and the work is imaged while repeating the cycle in which the exposure time of the image pickup device is adjusted within each scan rate. It is characterized by.
  • the scan rate is equally divided into the number of image pickup devices, and a plurality of image pickup devices are sequentially assigned to the divided scan rates, and the shutter of the image pickup device at the start point of each scan rate. Do the ring.
  • the exposure time of the imaging device is adjusted for each divided scan rate.
  • the original scan rate is divided, and a plurality of image pickup devices are used to pick up an image of the workpiece by repeating one cycle of imaging using the divided scan rate. Therefore, in the process of imaging the workpiece at a speed exceeding the optimum moving speed of the imaging device, the imaging device that follows the area that cannot be captured by the preceding imaging device captures the target imaging. Image data of the entire area can be acquired.
  • the exposure times of the line sensors of the respective image pickup devices do not overlap, it is possible to reconstruct the image of the work only by synthesizing the luminance value obtained from the output signal of each image pickup device.
  • it can be suitably implemented by an imaging device that can adjust the shuttering so that the exposure time is shorter than the divided scan rate.
  • the imaging unit captures an image of the workpiece while relatively horizontally moving an imaging unit including a plurality of imaging devices including line sensors and a holding table that holds the workpiece at a predetermined moving speed.
  • An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
  • the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the number of imagers.
  • the divided scan rate is sequentially assigned to the image pickup device, the shutter of the image pickup device is performed at the start point of each scan rate, the exposure time of the image pickup device is ended beyond the divided scan rate, and the preceding image pickup device
  • the work is imaged while repeating a cycle in which the exposure times of the subsequent imagers are overlapped, and the luminance value obtained by averaging the luminance values acquired over a plurality of pixels by the number of pixels for each imager is stored in the storage unit.
  • the image reconstruction process reads out the luminance values in the order obtained from the storage unit, amplifies the luminance value of the pixel at the time of calculation to the luminance value before averaging, and after the current amplification from the luminance value of the pixel calculated immediately before The image of the workpiece is reconstructed based on the luminance value obtained by subtracting the luminance value.
  • the brightness values output from the imagers are combined with each other.
  • the brightness of the pixel at the time of calculation is calculated.
  • the value is amplified to the luminance value before averaging, the luminance value obtained by subtracting the current luminance value after amplification from the luminance value of the pixel calculated immediately before is obtained, and the work image is reconstructed based on the luminance value. it can. Therefore, even an inexpensive imager that cannot adjust the exposure time can obtain a workpiece image at high speed without being limited by the scan rate of the imager itself.
  • the workpiece is moved while relatively moving an imaging unit including a plurality of imaging devices having the same plurality of line sensors and a holding table holding the workpiece at a predetermined moving speed.
  • An imaging process for imaging An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
  • the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor in accordance with the line sensor of the imaging device, Divide the scan rate evenly according to the number of licensors the imager has, A cycle in which the divided scan rates are sequentially assigned to the licensors for each image pickup device, shuttering is performed at the start point of each scan rate, and the exposure time for each line sensor is terminated within the divided scan rate.
  • the image reconstruction process reads the luminance values in the order of acquisition, amplifies the luminance value of the pixel at the time of calculation to the luminance value before averaging, and the luminance value after amplification from the luminance value of the pixel calculated immediately before The image of the workpiece is reconstructed based on the luminance value obtained by subtracting.
  • the imaging area per imaging device can be expanded.
  • the scan rate is divided according to the number of imagers, and the workpiece can be imaged in a state where the divided scan rate is assigned to each line sensor.
  • the luminance value for a plurality of pixels acquired over a plurality of line sensors for each image pickup device is output as a luminance value for one pixel by the integration delay circuit, the workpiece is imaged at high speed using the binning function. be able to.
  • the luminance value is read in the order of acquisition, and the luminance value of the pixel at the time of calculation is amplified to the luminance value before averaging
  • a detection process for detecting a relative positional relationship with the holding table for each of a plurality of imagers A calculation process for obtaining a relative shift amount between imagers from the positional relationship obtained in the detection process,
  • the image reconstruction process it is preferable to reconstruct the image while correcting the position of the acquired image data based on the amount of deviation obtained in the calculation process.
  • the present invention has the following configuration in order to achieve such an object.
  • an embodiment of a high-speed imaging device that images a workpiece, A holding table for holding the workpiece; An illumination unit that irradiates light toward the workpiece placed on the holding table; An imaging unit comprising a plurality of imagers equipped with a line sensor for imaging the workpiece; A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed; According to the number of imagers, adjust the moving speed faster than the optimum moving speed determined by the resolution and scan rate of the line sensor, and divide the scan rate equally to the number of imagers, The divided scan rates are assigned to the image pickup devices in order, and the image pickup device performs shuttering at the start point of each scan rate, and a plurality of units are repeated while repeating a cycle in which the exposure time of the image pickup device is adjusted within each scan rate.
  • a control unit that images the workpiece with an imaging device; An arithmetic processing unit that reconstructs an image of a workpiece based on the luminance value acquired by each of the imaging devices; It
  • the control unit adjusts the moving speed faster than the optimum moving speed determined from the resolution of the line sensor and the scan rate according to the number of imagers, and equalizes the scan rate to the number of imagers. Dividing and assigning the divided scan rates to the image pickup device in order, causing the image pickup device to perform shuttering at the start point of each scan rate, and repeating the cycle in which the exposure time of the image pickup device is adjusted within each scan rate
  • the workpiece is imaged by a plurality of imagers. Therefore, an embodiment of the above method can be suitably realized.
  • the high-speed imaging device A holding table for holding the workpiece; An illumination unit that irradiates light toward the workpiece placed on the holding table; An imaging unit comprising a plurality of imagers equipped with a line sensor for imaging the workpiece; A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed; According to the number of imagers, the moving speed is adjusted to be faster than the optimum moving speed determined from the resolution and scan rate of the line sensor, the scan rate is equally divided into the number of imagers, and the divided scan rate Are sequentially assigned to the image pickup devices, and the image pickup device performs shuttering at the start point of each scan rate, and the exposure time of the image pickup device is terminated beyond the scan rate after the division, and the preceding image pickup device and the subsequent image pickup operation are performed.
  • the image of the workpiece is captured by multiple imagers while repeating a cycle in which the exposure times of the machines overlap, and the brightness value obtained by averaging the brightness values acquired over multiple pixels for each imager is stored
  • a control unit to be stored in the unit Read out the luminance values in the order obtained from the storage unit, amplify the luminance value of the pixel at the time of calculation to the luminance value before averaging, and subtract the luminance value after amplification from the luminance value of the pixel calculated immediately before
  • the control unit adjusts the moving speed faster than the optimum moving speed determined from the resolution of the line sensor and the scan rate according to the number of imagers, and the scan rate is equal to the number of imagers.
  • Dividing and sequentially assigning the divided scan rate to the image pickup device causing the image pickup device to perform shuttering at the start point of each scan rate, and terminating the exposure time of the image pickup device beyond the divided scan rate,
  • the workpiece is imaged by a plurality of imagers while repeating a cycle in which the exposure times of the preceding imager and the subsequent imager overlap, and the luminance value acquired over a plurality of pixels is obtained for each imager.
  • the luminance value averaged in step (b) is stored in the storage unit. Therefore, an embodiment of the above method can be suitably realized.
  • other high-speed imaging device embodiments include: A holding table for holding the workpiece; An illumination unit that irradiates light toward the workpiece placed on the holding table; An imaging unit comprising a plurality of imagers having the same plurality of line sensors for imaging the workpiece; A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed; According to the line sensor of the image pickup device, it is adjusted to a moving speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor, and the scan rate is equally divided according to the number of licensors of the image pickup device, A cycle in which the scan rate after division for each imaging device is assigned to the licensor in order, shuttering is performed at the start point of each scan rate, and the exposure time for each line sensor is terminated within the scan rate after division.
  • the workpiece is imaged while repeating the imaging cycle in which the same part is overlapped alternately while shifting the imaging timing of the preceding imaging device and the succeeding imaging device, and acquired over a plurality of line sensors for each imaging device.
  • a control unit that stores a luminance value for a plurality of pixels in a storage unit as a luminance value for one pixel by an integration delay circuit; Read out the luminance values in the order obtained from the storage unit, amplify the luminance value of the pixel at the time of calculation to the luminance value before averaging, and subtract the luminance value after amplification from the luminance value of the pixel calculated immediately before An arithmetic processing unit for reconstructing an image of the workpiece based on the luminance value; It is provided with.
  • the control unit adjusts the moving speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the line sensor of the image pickup device, and according to the number of licensors of the image pickup device.
  • the scan rate is divided evenly, the divided scan rates are assigned to the licensors in order for each image pickup device, shuttering is performed at the start point of each scan rate, and exposure to each line sensor is performed within the divided scan rate.
  • the imaging cycle for alternately overlapping the same part while shifting the imaging timing of the preceding imaging device and the succeeding imaging device is repeated. While picking up images of the workpiece, multiple images were acquired across multiple line sensors for each imager. It is stored in the storage unit of luminance values of pixels as the luminance value of one pixel by the integral delay circuit. Therefore, an embodiment of the above method can be suitably realized.
  • the imaging device includes, for example, a lens barrel portion that guides light that has been irradiated from the illumination unit and reflected by the workpiece or light that has passed through the workpiece, An optical member that partially transmits light guided through the lens barrel and reflects a part of the light by changing the angle to guide the light to a plurality of imaging devices.
  • the image of the workpiece can be reconstructed with higher accuracy from the same condition with no positional deviation.
  • a detector that detects a relative position with the holding table is provided for each of the plurality of imaging devices
  • the control unit includes a storage unit that stores position information detected by the detector
  • the arithmetic processing unit reads out the position information acquired for each image pickup device from the stored amount, obtains a relative shift amount between the image pickup devices, and corrects the image while correcting the position of the acquired image data based on the shift amount. It is preferable to configure.
  • the high-speed imaging method and high-speed imaging device of the present invention enables high-speed imaging of a workpiece without being limited by the scan rate of the imaging machine.
  • wafer W a semiconductor wafer having a circuit pattern formed on the surface
  • wafer W a semiconductor wafer having a circuit pattern formed on the surface
  • FIG. 1 is a perspective view showing a schematic configuration of a high-speed imaging apparatus according to an embodiment of the present invention.
  • FIG. 2 is a front view showing a main part configuration of the high-speed imaging device, and includes a cross-sectional view in part.
  • the high-speed imaging device includes an imaging unit 1, an inspection stage 2, a control unit 3, and the like.
  • the imaging unit 1 includes a lens barrel body 4, a first imaging camera 5, a second imaging camera 6, an illumination unit 7, objective lenses 8a, 8b, 8c, a revolver 9, and the like.
  • the lens barrel body 4 is branched into two at the top, and a first imaging camera 5 and a second imaging camera 6 are provided in each of the lens barrels.
  • a plurality of objective lenses 8 a and 8 b having different magnifications are provided under the lens barrel body 4 via a revolver 9. That is, the imaging field of view can be changed.
  • the revolver 9 rotates about the axis P.
  • a lighting unit 7 is provided on the side surface of the barrel body 4.
  • the light from the irradiation unit 7 is guided to the lower wafer W to the connection portion of the irradiation unit 7 of the lens barrel body 4, and the incident light from the imaging unit 1 is positive from the front surface of the wafer W or the back surface side that has passed through the wafer W.
  • a first optical member 10 that totally reflects reflected light (hereinafter referred to as “observation light” as appropriate) is provided.
  • the first optical member 10 is, for example, a half mirror or a beam splitter.
  • a second optical member 11 that branches the observation light from the wafer W to the first imaging camera 5 and the second imaging camera 6 is provided at a branching portion of the lens barrel body 4. Note that the observation light branched by the second optical member 11 is totally reflected by the reflection mirror 12 and guided to the second imaging camera 6.
  • the second optical member 11 may be a half mirror or a beam splitter, for example.
  • the first imaging camera 5 and the second imaging camera 6 have the same scan rate.
  • line sensors 13a and 13b each having a one-dimensional array of image sensors such as a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor) are provided.
  • the imaging element digitally converts the luminance value according to the luminance of the observation light and outputs the luminance data.
  • the inspection stage 2 includes a holding table 14, a first movable table 15, a second movable table 16, a third movable table 17, and the like.
  • the holding table 14 is composed of a porous or metal chuck table that is larger and flatter than the wafer W.
  • the three movable platforms provided at the lower part of the holding table 14 are arranged in the order of the first movable table 15, the second movable table 16, and the third movable table 17 from the bottom.
  • the first movable base 15 includes a slider 15s that reciprocates in the Y-axis direction along a guide rail 15r laid on the apparatus base 15b.
  • the second movable table 16 is composed of a slider 16s that reciprocates in the X-axis direction along a guide rail 16r laid on a base 16b disposed on the slider 15s of the first movable table 15.
  • the third movable table 17 is rotated in the ⁇ direction by a motor 18 (for example, a direct drive motor) provided on the slider 16s of the second movable table 16.
  • a motor 18 for example, a direct drive motor
  • the movement in the X-axis direction is the main scanning direction.
  • the Y-axis direction is the direction in which the image sensors of the line sensors 13a and 13b are arranged and is the sub-scanning direction.
  • the 1st movable stand 15 and the 2nd movable stand 16 comprise the horizontal drive mechanism of this invention.
  • the control unit 3 generally controls the operations of the imaging unit 1 and the inspection stage 2, and includes a storage unit 20 and an arithmetic processing unit 21 therein. Details will be described along the operation description of the high-speed imaging device.
  • the moving speed of the slider 16s of the second movable stage 16 that is the main scanning direction of the inspection stage 2 is determined.
  • the optimum moving speed V1 is determined by the scan rates of the first imaging camera 5 and the second imaging camera 6. That is, it is determined by the resolution and scan rate of the line sensors 13a and 13b.
  • the exposure time for reaching a predetermined resolution is determined in advance by experiments and simulations. For example, when the scan rate of the first imaging camera 5 and the second imaging camera 6 is 10 kHz, one pixel is 10 ⁇ m, and the observation magnification is 10 times, the optimum moving speed of the first imaging camera 5 and the second imaging camera 6 V1 is 10 mm / sec.
  • the imaging unit 1 includes the first imaging camera 5 and the second imaging camera 6 before and after the main scanning direction
  • the main of the slider 16s of the second movable table 16 is provided.
  • the scanning speed V2 is set to 20 mm / sec, which is twice the optimum moving speed V1, and is set so that the imaging by both the imaging cameras 5 and 6 is performed alternately.
  • Each of these conditions is stored in the storage unit 20 of the control unit 3.
  • the exposure times of the first imaging camera 5 and the second imaging camera 6 are set slightly shorter than the scan rate after the division, but an imaging camera capable of adjusting the timing of shuttering is used. Change settings as appropriate within the scan rate. That is, the state in which the shuttering timing is not adjusted is the timing indicated by the broken lines 51 and 61, but the state in which the exposure time is shortened by adjusting the shuttering timing is the timing indicated by the solid lines 52 and 62.
  • the wafer W is unloaded from the cassette by a transfer robot or the like, and placed on the holding table 14 as shown in FIG.
  • the wafer W is aligned based on an orientation flat or a V notch formed in the outer peripheral region. That is, the first movable table 15 and the second movable table 16 are moved and aligned, and the third movable table 17 is rotated around the rotation axis of the motor 18 to align the wafer W.
  • the main scanning speed of the slider 16s of the second movable table 16 is moved after the imaging unit 1 is moved and set to a predetermined height. Imaging of the wafer W is started while scanning V2 in the X-axis direction at twice the optimum moving speed V1.
  • the trigger signal 1 is transmitted from the control unit 3 to the first imaging camera 5
  • the shutter of the first imaging camera 5 is received and imaging is started. The observation light is exposed to the line sensor 13a.
  • the shutter of the second imaging camera 6 is turned on in response thereto, imaging is started, and observation light is exposed to the line sensor 13 b.
  • the trigger signal 1 and the trigger signal 2 are alternately output.
  • the first imaging camera 5 and the second imaging camera 6 set the shuttering time to half of the normal (that is, the state indicated by the broken lines 51 and 61) (that is, the state indicated by the solid lines 52 and 62). Keep it.
  • the first imaging camera 5 and the second imaging camera 6 are generally configured to output image data after the normal shuttering time has elapsed even if the shuttering time is set short. Therefore, after the output signals from both the imaging cameras 5 and 6 are in the OFF state indicated by the broken lines 51 and 61, both the imaging cameras 4 are represented as the luminance data 1a, 1b... And the luminance data 2a, 2b. , 6 are alternately output. By doing so, imaging is performed at an apparently double scan rate using the two imaging cameras 5 and 6 while moving the workpiece at twice the speed.
  • FIG. 5 shows an image pattern to be imaged, and the luminance value (90) of the image pattern divided into a matrix is shown.
  • the blank portion means that the luminance value is zero.
  • the vertical axis shows the time of imaging: t0 to t16
  • the horizontal axis shows the address (1 to 16) of the line sensor used for imaging.
  • timings (t1a to t8a, t1b to t8b) at which the shutters of the first imaging camera 5 and the second imaging camera 6 are turned on are also shown. That is, at time t2, at the address 8 and 9 of the line sensor, the first imaging camera 5 is used to capture 90 luminance portions at the timing t2a when the shutter is turned on.
  • the second imaging camera 6 is used to capture 90 luminance portions at the timing t2b when the shutter is turned on.
  • the series of continuous imaging processes is defined as one cycle, and the wafer W is imaged by both imaging cameras 5 and 6 while repeating the cycle while scanning from one end of the wafer W to the other end.
  • Step S4 Image Reconstruction Processing Processing for performing image reconstruction by performing the above-described series of continuous imaging processing cycles and then image reconstruction will be described.
  • FIG. 6A shows luminance data output from the first imaging camera 5
  • FIG. 6B shows luminance data output from the second imaging camera 6.
  • the imaging timing and the data output timing of the first imaging camera 5 and the second imaging camera 6 are alternately performed as shown in FIGS. Therefore, as shown in FIG. 6A, the luminance data is respectively output from the first imaging camera 5 at the data output timings corresponding to the images captured at the timings t1a to t8a when the shutter is turned on (that is, the times d1a to d8a). Is output. Further, as shown in FIG.
  • the luminance data is respectively output from the second imaging camera 6 at the data output timing corresponding to the image captured at the timing t1b to t8b when the shutter is turned on (that is, the times d1b to d8b). Is output.
  • the signals output from both the imaging cameras 5 and 6 are A / D converted and stored in the storage unit 20 as brightness values separately for each of the first imaging camera 5 and the second imaging camera 6.
  • the arithmetic processing unit 21 reads the luminance values of the two imaging cameras 5 and 6 from the storage unit 20, and alternately arranges the read luminance values in order from the oldest one as shown in FIG. Reconstruct the image.
  • the luminance value stored in the storage unit 20 is half the original value (45). Therefore, when performing the image reconstruction process, in consideration of this, a process of calculating a value (90) obtained by doubling the luminance value is also performed.
  • Step S5 Wafer Unloading
  • the wafer W is sucked by a transfer robot or the like and transferred to a cassette (not shown). This completes the process of acquiring a series of inspection images, and thereafter the same process is repeated (step S6).
  • the entire surface of the wafer W cannot be continuously imaged by one imaging camera.
  • the above-described embodiment apparatus by alternately switching the imaging of the imaging cameras 5 and 6 at the timing when the scan rate is divided into two according to the number of imaging cameras, and further setting the exposure time in half. While the exposure time of each of the first imaging camera 5 and the second imaging camera 6 is halved, continuous image data can be acquired without interruption of the entire wafer image.
  • the entire image of the wafer W can be easily reconstructed by simply synthesizing based on the acquired image data (luminance value). That is, since the image of the wafer W can be acquired easily and accurately even at a speed V2 that is twice the optimum moving speed V1 of the imaging camera, the throughput of the inspection process can be increased.
  • the present invention is not limited to the embodiment described above, and can be modified as follows.
  • Step S3 ′ Imaging Start
  • the imaging unit 1 is moved and set to a predetermined height, and then the main scanning of the slider 16s of the second movable table 16 is performed. Imaging of the wafer W is started while scanning the speed V2 in the X-axis direction at twice the optimum moving speed V1.
  • the trigger signal 1 is transmitted from the control unit 3 to the first imaging camera 5
  • the shutter of the first imaging camera 5 is turned on and imaging is started. The observation light is exposed to the line sensor 13a.
  • the shutter of the second imaging camera 6 is turned on in response thereto, imaging is started, and observation light is exposed to the line sensor 13 b.
  • the first imaging camera 5 and the second imaging camera 6 have a normal shuttering time (that is, a state indicated by solid lines 53 and 63), and perform imaging while alternately overlapping the same part. .
  • imaging is performed at an apparently double scan rate using the two imaging cameras 5 and 6 while moving the workpiece at a double speed.
  • FIG. 8 shows an image pattern to be imaged, and the luminance value (90) of the image pattern divided into a matrix is shown.
  • the blank portion means that the luminance value is zero.
  • the vertical axis shows the time of imaging: t0 to t16, and the horizontal axis shows the address (1 to 16) of the line sensor used for imaging. Further, on the right side of the figure, timings (t1a to t8a, t1b to t8b) at which the shutters of the first imaging camera 5 and the second imaging camera 6 are turned on are also shown.
  • the first imaging camera 5 is used to capture 90 luminance portions at the timing t2a when the shutter is turned on.
  • the second imaging camera 6 is used to capture the 90 brightness portion at the timing t2b when the shutter is turned on.
  • the series of continuous imaging processes is defined as one cycle, and the wafer W is imaged by both imaging cameras 5 and 6 while repeating the cycle while scanning from one end of the wafer W to the other end.
  • Step S4 ′ Image Reconstruction Process A process for capturing an image by performing the above-described series of continuous imaging process cycles and then reconstructing the image will be described.
  • FIG. 9A shows luminance data output from the first imaging camera 5
  • FIG. 9B shows luminance data output from the second imaging camera 6.
  • the imaging timing and the data output timing of the first imaging camera 5 and the second imaging camera 6 are alternately performed as shown in FIGS. Therefore, as shown in FIG. 9A, the luminance data is respectively output from the first imaging camera 5 at the data output timings corresponding to the images captured at the timings t1a to t8a when the shutter is turned on (that is, the times d1a to d8a). Is output. Further, as shown in FIG. 9B, the luminance data is respectively output from the second imaging camera 6 at the data output timing corresponding to the image captured at the timing t1b to t8b when the shutter is turned on (that is, the times d1b to d8b). Is output.
  • step S4 The signals output from both the imaging cameras 5 and 6 are A / D converted and stored in the storage unit 20 as brightness values separately for each of the first imaging camera 5 and the second imaging camera 6. Since imaging is performed over two pixels for a long time, the two pixels are averaged and the luminance value is stored. Therefore, based on the following procedure, taking into account that the luminance values acquired by the two cameras are averaged in time series and also acquired by the other camera in an overlapping manner. Then, image reconstruction processing is performed (these are different from step S4).
  • the first half of exposure when the current imaging camera receiving the trigger signal starts imaging.
  • the output signal within the time and the output signal of the second half exposure time of the preceding imaging camera overlap and are output.
  • the luminance value obtained based on both output signals is stored in the storage unit 20 as a measured luminance value obtained by combining the luminance values to be acquired in advance.
  • addresses 8 and 9 will be described as follows. First, an image captured at time t1a by the first imaging camera 5 is output with a luminance value (B) of 0 at time d1a. Further, the luminance value (C) of this place is set to 0 as the luminance value (A) of the immediately preceding pixel. Therefore, the portion corresponding to the addresses 8 and 9 at the time d1a is calculated as the luminance value 0. Subsequently, the image captured at the time t1b by the second imaging camera 6 is output with a luminance value (B) of 45 at the time d1b. In addition, the luminance value (A) of the immediately preceding pixel is calculated as 0 as the luminance value (C) of this place. Therefore, the portion corresponding to the addresses 8 and 9 at the time d1b is calculated as the luminance value 90.
  • the image captured at time t2a by the first imaging camera 5 is output with a luminance value (B) of 45 at time d2a.
  • the luminance value (C) of the previous pixel is set to 90 as the luminance value (A) of the immediately preceding pixel. Therefore, the portion corresponding to the addresses 8 and 9 at the time d2a is calculated as the luminance value 0.
  • the scanning speed of the imaging camera is not limited, and the optimum moving speed is achieved. It is possible to realize imaging at twice the speed V2 exceeding V1.
  • the first imaging camera 5 and the second imaging camera 6 may be configured to include a plurality of line sensors.
  • line sensors are arranged adjacently before and after in the main scanning direction, and the luminance value at the same address acquired by each line sensor is subjected to time delay integration processing (so-called TDI (Time Delay Integration) processing).
  • TDI Time Delay Integration
  • This configuration may be realized by combining a plurality of separate line sensors and a TDI circuit, or a commonly available so-called TDI camera (one in which the above configuration is integrated) may be used.
  • the scanning speed of the line sensor itself is the optimum moving speed V1 as in the above embodiment, the luminance values acquired by a plurality of sensors are subjected to time delay integration processing, Sensitivity imaging can be realized. Therefore, when the brightness value of the workpiece is low, it is preferable to inspect using such a camera. However, when the moving speed of the workpiece does not coincide with the optimum moving speed V1, the timing of the time delay integration process does not match and predetermined acquired image data cannot be obtained. Therefore, in the modification according to the present invention, when a TDI camera is used, the following step S3 ′′ is performed instead of the above-described step S3 ′.
  • the imaging unit 1 is moved and set to a predetermined height, and then the main scanning of the slider 16s of the second movable table 16 is performed.
  • the imaging of the wafer W is started while scanning with the speed V2 set to twice the optimum moving speed V1 in the X-axis direction
  • the first imaging camera 5 and the second imaging camera 6 are, for example, main It is configured using a TDI camera provided with four lines of line sensors and a time delay integration processing circuit in the scanning direction.
  • the trigger signal 1 and the trigger signal 2 are alternately transmitted from the control unit 3 to the first imaging camera 5 and the second imaging camera 6. deep.
  • the first imaging camera 5 and the second imaging camera 6 are configured to perform imaging while alternately overlapping the same part. Then, imaging is performed using the two imaging cameras 5 and 6 while moving the workpiece at the main scanning speed V2.
  • FIG. 10 shows an image pattern to be imaged, and the luminance value (20) of the image pattern divided into a matrix is shown.
  • the blank portion means that the luminance value is zero.
  • the vertical axis shows the time of imaging: t0 to t16, and the horizontal axis shows the address (1 to 16) of the line sensor used for imaging.
  • the first imaging camera 5 is at the position shown in FIG. 11A at time t3 and at the position shown in FIG. 11B at time t5. Then, the luminance data of the previous stage captured and acquired using the first line sensor group from time t2 to t3 is sent to the subsequent stage by TDI processing, and imaged and acquired using the second line sensor group from time t4 to t5. The subsequent luminance data and integration processing are performed. Then, the integrated value for a predetermined number of steps (two in the above example) is output to the outside as luminance data for one imaging at time d2a.
  • an image is constructed based on the output signals of a plurality of times of imaging, as shown in FIG.
  • the second imaging camera 6 is attached so as to observe a position shifted by one pixel in the main scanning direction from the imaging position of the first imaging camera 5. Therefore, the second imaging camera 6 observes the position shown in FIG. 12A at time t4 and observes the position shown in FIG. 12B at time t6. Then, the previous luminance data captured and acquired using the first line sensor group from time t3 to t4 is sent to the subsequent stage in the TDI processing, and imaged and acquired using the second line sensor group from time t5 to t6. The subsequent luminance data and integration processing are performed. Then, the integrated values for a predetermined number of steps (two in the above example) are output to the outside as luminance data for one imaging at time d2b. Then, when an image is constructed based on the output signals of a plurality of times of imaging, a portion where luminance values overlap is generated as shown in FIG.
  • the arithmetic processing unit 21 can reconstruct a desired whole image by performing the image reconstruction process similar to the modification (1). . Moreover, by performing TDI processing using a plurality of line sensors, it is possible to acquire image data obtained by amplifying the luminance value as shown in FIG.
  • a workpiece can be imaged with higher sensitivity than when an imaging unit configured with an imaging camera including a single line sensor is used.
  • the relative positional relationship with the holding table 14 for each of the first imaging camera 5 and the second imaging camera 6 is obtained by the sensor or the preliminary imaging of each imaging camera.
  • the relative shift amount between the imaging cameras may be obtained, and the image may be corrected according to the shift amount.
  • the imaging unit 1 includes the two first imaging cameras 5 and the second imaging camera 6, but the number is not limited thereto. That is, the number of imaging cameras may be two or more.
  • the moving speed of the second movable table 16 can be increased every time the number of imaging cameras is increased.
  • the optimal moving speed V1 ⁇ the number of imaging cameras is set, and the slider 16s of the second movable base 16 is moved.
  • the scan rate is equally divided into the number of the images, the images are alternately captured at the divided timing, and the time until the imaging timing is switched may be set as the exposure time of each imaging camera.
  • the number of line sensors arranged in parallel in the main scanning direction and the number of pixels to be binned are appropriately set according to the main scanning speed to be set and the desired sensitivity enhancement. To do.

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Abstract

An objective of the present invention is to capture an image of a workpiece at high speed without being dependent upon the image capture characteristics of an image capture camera. Specifically, in an image capture process wherein a workpiece is image captured while relatively horizontally moving at a prescribed movement speed an image capture unit formed from a plurality of image capture devices comprising line sensors and a retaining table which retains the workpiece: the movement speeds are adjusted, according to the number of image capture devices, to faster speeds than the optimal movement speeds as determined from the resolutions and scan rate of the line sensors; the scan rate is divided into equal segments according to the number of image capture devices; image capture of the workpiece is carried out while repeating a cycle of the scan rate being allocated sequentially to the image capture devices, shuttering of the image capture devices being carried out at the start point of each scan rate, and the exposure time of the image capture device being adjusted within each scan rate; and an image of the workpiece is reconstructed on the basis of brightness values which are acquired from each of the image capture devices.

Description

高速撮像方法および高速撮像装置High speed imaging method and high speed imaging apparatus
　本発明は、ガラス、半導体ウエハおよび電子基板などのワークを撮像する高速撮像方法および高速撮像装置に関する。 The present invention relates to a high-speed imaging method and a high-speed imaging device for imaging a workpiece such as glass, a semiconductor wafer, and an electronic substrate.
　エリアイメージセンサを走査方向に移動させる過程で、移動軌跡上の所定位置と移動方向と直行する水平方向に１／２画素ずらした位置への移動を交互に繰り返しながら撮像する方法が提案および実施されている（特許文献１）。 In the process of moving the area image sensor in the scanning direction, a method has been proposed and implemented in which imaging is performed while alternately repeating a predetermined position on the movement locus and a position shifted by 1/2 pixel in the horizontal direction perpendicular to the moving direction. (Patent Document 1).
特許第３９０７５６０号公報Japanese Patent No. 3907560
　しかしながら、撮像対象のワークとして、例えば半導体デバイスなどは、単位時間当たりの製造数量を増やすために、画像解析処理による検査装置などにおいて高いスループットが求められている。そこで、基板１枚当たりに費やす検査時間を短縮するために、ワークを保持する保持ステージの移動を高速化したり、或いは複数台の撮像カメラを配置したりする形態が提案されている。 However, as a workpiece to be imaged, for example, a semiconductor device or the like is required to have a high throughput in an inspection apparatus or the like by image analysis processing in order to increase the manufacturing quantity per unit time. Therefore, in order to reduce the inspection time spent per substrate, a form has been proposed in which the movement of the holding stage for holding the workpiece is accelerated or a plurality of imaging cameras are arranged.
　保持ステージの移動を高速化するのは容易である。しかしながら、撮像カメラのスキャンレートを超える高速撮像を行うと本来取得すべき画像データと異なる画像が出力される。すなわち、撮像カメラの分解能とスキャンレートから決まる最適移動速度を超えてワークを撮像できないといった問題がある。 It is easy to speed up the movement of the holding stage. However, when high-speed imaging exceeding the scan rate of the imaging camera is performed, an image different from the image data to be originally acquired is output. That is, there is a problem that the workpiece cannot be imaged exceeding the optimum moving speed determined by the resolution and scan rate of the imaging camera.
　本発明はこのような事情に鑑みてなされたものであって、撮像機のスキャンレートに制限されることなくワークを高速に撮像することのできる高速撮像方法および高速撮像装置を提供することを主たる目的としている。 The present invention has been made in view of such circumstances, and it is a main object of the present invention to provide a high-speed imaging method and a high-speed imaging device capable of imaging a workpiece at high speed without being limited by the scan rate of the imaging device. It is aimed.
　この発明は、このような目的を達成するために、次のような構成をとる。 This invention has the following configuration in order to achieve such an object.
　すなわち、ワークを撮像する高速撮像方法の一実施形態であって、
　ラインセンサを備えた複数台の撮像機からなる撮像ユニットと前記ワークを保持する保持テーブルとを所定の移動速度で相対的に水平移動させながら当該ワークを撮像する撮像過程と、
　前記各撮像機から取得した輝度値に基づいてワークの画像を再構成する画像再構成過程を備え、
　前記撮像過程は、前記移動速度を撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い速度に調整し、
　前記撮像機の台数に応じてスキャンレートを均等に分割し、
　分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機のシャッタリングを行うとともに、各スキャンレート内で撮像機の露光時間を調整したサイクルを繰り返しながら前記ワークを撮像する
　ことを特徴とする。 That is, an embodiment of a high-speed imaging method for imaging a workpiece,
An imaging process for imaging the workpiece while relatively horizontally moving an imaging unit composed of a plurality of imaging devices equipped with line sensors and a holding table for holding the workpiece, at a predetermined moving speed;
An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
In the imaging process, the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the number of imagers.
Divide the scan rate evenly according to the number of imagers,
The divided scan rates are assigned to the image pickup device in order, the image pickup device is shuttered at the start point of each scan rate, and the work is imaged while repeating the cycle in which the exposure time of the image pickup device is adjusted within each scan rate. It is characterized by.
　（作用・効果）　この方法によれば、撮像機の台数分にスキャンレートを均等に分割し、当該分割したスキャンレートに複数台の撮像機を順番に割当て各スキャンレートの始点で撮像機のシャッタリングを行う。このとき、分割後のスキャンレートごとに撮像機の露光時間が調整される。オリジナルのスキャンレートを分割し、複数台の撮像機で分割後のスキャンレートを利用した１サイクルの撮像を繰り返してワークを撮像する。したがって、撮像機の最適移動速度を超えた速度でワークを撮像している過程で、先行する撮像機によって撮像しきれないエリアの画像を後方から追従する撮像機が撮像するので、目的とする撮像エリア全体の画像データを取得することができる。なお、各撮像機のラインセンサの露光時間は重複しないので、各撮像機の出力信号から求めた輝度値を合成するだけでワークの画像を再構成することができる。換言すれば、露光時間を分割後のスキャンレートよりも短い時間となるようシャッタリングを調整可能な撮像機によって好適に実施することができる。 (Function / Effect) According to this method, the scan rate is equally divided into the number of image pickup devices, and a plurality of image pickup devices are sequentially assigned to the divided scan rates, and the shutter of the image pickup device at the start point of each scan rate. Do the ring. At this time, the exposure time of the imaging device is adjusted for each divided scan rate. The original scan rate is divided, and a plurality of image pickup devices are used to pick up an image of the workpiece by repeating one cycle of imaging using the divided scan rate. Therefore, in the process of imaging the workpiece at a speed exceeding the optimum moving speed of the imaging device, the imaging device that follows the area that cannot be captured by the preceding imaging device captures the target imaging. Image data of the entire area can be acquired. In addition, since the exposure times of the line sensors of the respective image pickup devices do not overlap, it is possible to reconstruct the image of the work only by synthesizing the luminance value obtained from the output signal of each image pickup device. In other words, it can be suitably implemented by an imaging device that can adjust the shuttering so that the exposure time is shorter than the divided scan rate.
　また、他の実施形態は、ラインセンサを備えた複数台の撮像機からなる撮像ユニットと前記ワークを保持する保持テーブルとを所定の移動速度で相対的に水平移動させながら当該ワークを撮像する撮像過程と、
　前記各撮像機から取得した輝度値に基づいてワークの画像を再構成する画像再構成過程を備え、
　前記撮像過程は、前記移動速度を撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い速度に調整し、
　前記撮像機の台数に応じてスキャンレートを均等に分割し、
　分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機のシャッタリングを行うとともに、分割後のスキャンレートを超えて撮像機の露光時間を終了させ、先行の撮像機と後行の撮像機の露光時間をオーバーラップさせたサイクルを繰り返しながら前記ワークを撮像し、複数画素分にわたって取得された輝度値を撮像機ごとに画素数で平均化した輝度値を記憶部に格納し、
　前記画像再構成過程は、記憶部から取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する
　ことを特徴とする。 In another embodiment, the imaging unit captures an image of the workpiece while relatively horizontally moving an imaging unit including a plurality of imaging devices including line sensors and a holding table that holds the workpiece at a predetermined moving speed. Process,
An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
In the imaging process, the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the number of imagers.
Divide the scan rate evenly according to the number of imagers,
The divided scan rate is sequentially assigned to the image pickup device, the shutter of the image pickup device is performed at the start point of each scan rate, the exposure time of the image pickup device is ended beyond the divided scan rate, and the preceding image pickup device The work is imaged while repeating a cycle in which the exposure times of the subsequent imagers are overlapped, and the luminance value obtained by averaging the luminance values acquired over a plurality of pixels by the number of pixels for each imager is stored in the storage unit. Store and
The image reconstruction process reads out the luminance values in the order obtained from the storage unit, amplifies the luminance value of the pixel at the time of calculation to the luminance value before averaging, and after the current amplification from the luminance value of the pixel calculated immediately before The image of the workpiece is reconstructed based on the luminance value obtained by subtracting the luminance value.
　この方法によれば、先行および後行の撮像機の露光時間をオーバーラップさせて撮像するので、各撮像機から出力される輝度値は、互いに合成されている、しかしながら、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値を求め、当該輝度値に基づいてワークの画像を再構成するができる。したがって、露光時間が調整できない安価な撮像機であっても撮像機自体のスキャンレートに制限されることなく、ワークの画像を高速に取得することができる。 According to this method, since the exposure times of the preceding and succeeding imagers are overlapped, the brightness values output from the imagers are combined with each other. However, the brightness of the pixel at the time of calculation is calculated. The value is amplified to the luminance value before averaging, the luminance value obtained by subtracting the current luminance value after amplification from the luminance value of the pixel calculated immediately before is obtained, and the work image is reconstructed based on the luminance value. it can. Therefore, even an inexpensive imager that cannot adjust the exposure time can obtain a workpiece image at high speed without being limited by the scan rate of the imager itself.
　さらに、他の実施形態は、同じ複数本のラインセンサを有する複数台の撮像機を備えた撮像ユニットと前記ワークを保持する保持テーブルとを所定の移動速度で相対的に水平移動させながら当該ワークを撮像する撮像過程と、
　前記各撮像機から取得した輝度値に基づいてワークの画像を再構成する画像再構成過程を備え、
　前記撮像過程は、前記移動速度を撮像機のラインセンサに応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い速度に調整し、
　前記撮像機の有するライセンサの本数に応じてスキャンレートを均等に分割し、
　前記撮像機ごとに分割後のスキャンレートをライセンサに順番に割当て、各スキャンレートの始点でシャッタリングを行うとともに、分割後のスキャンレート内で各ラインセンサへの露光時間を終了させるよう調整したサイクルを繰り返しながら前記ワークを撮像させる過程で、
　先行の撮像機と後行の撮像機の撮像タイミングをずらしながら交互に同一部位をオーバーラップさせる撮像サイクルを繰り返しながら前記ワークを撮像し、撮像機ごとに複数本のラインセンサにわたって取得された複数画素分の輝度値を積分遅延回路により１画素分の輝度値として記憶部に格納し、
　前記画像再構成過程は、取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する
　ことを特徴とする。 Furthermore, in another embodiment, the workpiece is moved while relatively moving an imaging unit including a plurality of imaging devices having the same plurality of line sensors and a holding table holding the workpiece at a predetermined moving speed. An imaging process for imaging
An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
In the imaging process, the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor in accordance with the line sensor of the imaging device,
Divide the scan rate evenly according to the number of licensors the imager has,
A cycle in which the divided scan rates are sequentially assigned to the licensors for each image pickup device, shuttering is performed at the start point of each scan rate, and the exposure time for each line sensor is terminated within the divided scan rate. In the process of imaging the workpiece while repeating
A plurality of pixels acquired across a plurality of line sensors for each image pickup device by imaging the workpiece while repeating an imaging cycle that alternately overlaps the same part while shifting the image pickup timing of the preceding image pickup device and the subsequent image pickup device. Is stored in the storage unit as a luminance value for one pixel by an integration delay circuit,
The image reconstruction process reads the luminance values in the order of acquisition, amplifies the luminance value of the pixel at the time of calculation to the luminance value before averaging, and the luminance value after amplification from the luminance value of the pixel calculated immediately before The image of the workpiece is reconstructed based on the luminance value obtained by subtracting.
　この方法によれば、１台の撮像機が複数本のラインセンサを有しているので、１台の撮像機当たりの撮像領域を広げることができる。また、撮像機の台数に応じてスキャンレートを分割し、分割後のスキャンレートを各ラインセンサに割り当てた状態でワークの撮像を可能にする。ここで、撮像機ごとに複数本のラインセンサにわたって取得された複数画素分の輝度値を積分遅延回路により１画素分の輝度値として出力するので、ビニング機能を利用してワークを高速に撮像することができる。なお、先行する撮像機と後行する撮像機によって撮像される領域が重複する部分が生じるが、取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成することにより、重複分の輝度値を除去した鮮明なワークの画像を再構成することができる。 According to this method, since one imaging device has a plurality of line sensors, the imaging area per imaging device can be expanded. In addition, the scan rate is divided according to the number of imagers, and the workpiece can be imaged in a state where the divided scan rate is assigned to each line sensor. Here, since the luminance value for a plurality of pixels acquired over a plurality of line sensors for each image pickup device is output as a luminance value for one pixel by the integration delay circuit, the workpiece is imaged at high speed using the binning function. be able to. In addition, although the part imaged by the preceding imager and the subsequent imager overlaps, the luminance value is read in the order of acquisition, and the luminance value of the pixel at the time of calculation is amplified to the luminance value before averaging A clear work image with the overlapped brightness value removed by reconstructing the work image based on the brightness value obtained by subtracting the current amplified brightness value from the pixel brightness value calculated immediately before Can be reconfigured.
　さらに、上記各実施形態において、複数台の撮像機ごとに保持テーブルとの相対的な位置関係を検出する検出過程と、
　検出過程で求めた前記位置関係から撮像機同士の相対的なズレ量を求める演算過程を備え、
　画像再構成過程は、演算過程で求まったズレ量に基づいて、取得画像データの位置を補正しながら画像を再構成することが好ましい。 Further, in each of the above embodiments, a detection process for detecting a relative positional relationship with the holding table for each of a plurality of imagers,
A calculation process for obtaining a relative shift amount between imagers from the positional relationship obtained in the detection process,
In the image reconstruction process, it is preferable to reconstruct the image while correcting the position of the acquired image data based on the amount of deviation obtained in the calculation process.
　この方法によれば、各撮像機の位置ズレがオフセットされるので、微妙な位置調整を行う手間を省きつつ正確な位置合わせが容易にでき、画像を再構成することができる。 According to this method, since the position shift of each image pickup device is offset, accurate alignment can be easily performed and the image can be reconstructed while omitting the trouble of performing fine position adjustment.
　また、この発明は、このような目的を達成するために、次のような構成をとる。 Also, the present invention has the following configuration in order to achieve such an object.
　すなわち、ワークを撮像する高速撮像装置の一実施形態であって、
　前記ワークを保持する保持テーブルと、
　前記保持テーブルに載置されたワークに向けて光を照射する照明ユニットと、
　前記ワークを撮像するラインセンサを備えた複数台の撮像機からなる撮像ユニットと、
　前記保持テーブルと撮像ユニットを所定の移動速度で相対的に水平移動させる水平駆動機構と、
　前記撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、スキャンレートを撮像機の台数分に均等に分割し、
分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機にシャッタリングを行わせるとともに、各スキャンレート内で撮像機の露光時間を調整したサイクルを繰り返しながら複数台の撮像機で前記ワークを撮像させる制御部と、
　前記各撮像機によって取得された輝度値に基づいてワークの画像を再構成する演算処理部と、
　を備えたことを特徴とする。 That is, an embodiment of a high-speed imaging device that images a workpiece,
A holding table for holding the workpiece;
An illumination unit that irradiates light toward the workpiece placed on the holding table;
An imaging unit comprising a plurality of imagers equipped with a line sensor for imaging the workpiece;
A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed;
According to the number of imagers, adjust the moving speed faster than the optimum moving speed determined by the resolution and scan rate of the line sensor, and divide the scan rate equally to the number of imagers,
The divided scan rates are assigned to the image pickup devices in order, and the image pickup device performs shuttering at the start point of each scan rate, and a plurality of units are repeated while repeating a cycle in which the exposure time of the image pickup device is adjusted within each scan rate. A control unit that images the workpiece with an imaging device;
An arithmetic processing unit that reconstructs an image of a workpiece based on the luminance value acquired by each of the imaging devices;
It is provided with.
　この構成によれば、制御部が、像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、スキャンレートを撮像機の台数分に均等に分割し、分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機にシャッタリングを行わせるとともに、各スキャンレート内で撮像機の露光時間を調整したサイクルを繰り返しながら複数台の撮像機でワークを撮像させる。したがって、上記方法の一実施形態を好適に実現することができる。 According to this configuration, the control unit adjusts the moving speed faster than the optimum moving speed determined from the resolution of the line sensor and the scan rate according to the number of imagers, and equalizes the scan rate to the number of imagers. Dividing and assigning the divided scan rates to the image pickup device in order, causing the image pickup device to perform shuttering at the start point of each scan rate, and repeating the cycle in which the exposure time of the image pickup device is adjusted within each scan rate The workpiece is imaged by a plurality of imagers. Therefore, an embodiment of the above method can be suitably realized.
　また、他の高速撮像装置の実施形態は、
　前記ワークを保持する保持テーブルと、
　前記保持テーブルに載置されたワークに向けて光を照射する照明ユニットと、
　前記ワークを撮像するラインセンサを備えた複数台の撮像機からなる撮像ユニットと、
　前記保持テーブルと撮像ユニットを所定の移動速度で相対的に水平移動させる水平駆動機構と、
　前記撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、スキャンレートを撮像機の台数分に均等に分割し、分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機にシャッタリングを行わせるとともに、分割後のスキャンレートを超えて撮像機の露光時間を終了させ、先行の撮像機と後行の撮像機の露光時間をオーバーラップさせたサイクルを繰り返させながら複数台の撮像機で前記ワークを撮像させ、複数画素分にわたって取得された輝度値を撮像機ごとに画素数で平均化した輝度値を記憶部に格納させる制御部と、
　前記記憶部から取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する演算処理部と、
　を備えたことを特徴とする。 In addition, other embodiments of the high-speed imaging device
A holding table for holding the workpiece;
An illumination unit that irradiates light toward the workpiece placed on the holding table;
An imaging unit comprising a plurality of imagers equipped with a line sensor for imaging the workpiece;
A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed;
According to the number of imagers, the moving speed is adjusted to be faster than the optimum moving speed determined from the resolution and scan rate of the line sensor, the scan rate is equally divided into the number of imagers, and the divided scan rate Are sequentially assigned to the image pickup devices, and the image pickup device performs shuttering at the start point of each scan rate, and the exposure time of the image pickup device is terminated beyond the scan rate after the division, and the preceding image pickup device and the subsequent image pickup operation are performed. The image of the workpiece is captured by multiple imagers while repeating a cycle in which the exposure times of the machines overlap, and the brightness value obtained by averaging the brightness values acquired over multiple pixels for each imager is stored A control unit to be stored in the unit,
Read out the luminance values in the order obtained from the storage unit, amplify the luminance value of the pixel at the time of calculation to the luminance value before averaging, and subtract the luminance value after amplification from the luminance value of the pixel calculated immediately before An arithmetic processing unit for reconstructing an image of the workpiece based on the luminance value;
It is provided with.
　この構成によれば、制御部が、撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、スキャンレートを撮像機の台数分に均等に分割し、分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機にシャッタリングを行わせるとともに、分割後のスキャンレートを超えて撮像機の露光時間を終了させ、先行の撮像機と後行の撮像機の露光時間をオーバーラップさせたサイクルを繰り返しながら複数台の撮像機で前記ワークを撮像させ、複数画素分にわたって取得された輝度値を撮像機ごとに画素数で平均化した輝度値を記憶部に格納させる。したがって、上記方法の一実施形態を好適に実現することができる。 According to this configuration, the control unit adjusts the moving speed faster than the optimum moving speed determined from the resolution of the line sensor and the scan rate according to the number of imagers, and the scan rate is equal to the number of imagers. Dividing and sequentially assigning the divided scan rate to the image pickup device, causing the image pickup device to perform shuttering at the start point of each scan rate, and terminating the exposure time of the image pickup device beyond the divided scan rate, The workpiece is imaged by a plurality of imagers while repeating a cycle in which the exposure times of the preceding imager and the subsequent imager overlap, and the luminance value acquired over a plurality of pixels is obtained for each imager. The luminance value averaged in step (b) is stored in the storage unit. Therefore, an embodiment of the above method can be suitably realized.
　さらに、他の高速撮像装置の実施形態は、
　前記ワークを保持する保持テーブルと、
　前記保持テーブルに載置されたワークに向けて光を照射する照明ユニットと、
　前記ワークを撮像する同じ複数本のラインセンサを有する複数台の撮像機からなる撮像ユニットと、
　前記保持テーブルと撮像ユニットを所定の移動速度で相対的に水平移動させる水平駆動機構と、
　前記撮像機のラインセンサに応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、記撮像機の有するライセンサの本数に応じてスキャンレートを均等に分割し、撮像機ごとに分割後のスキャンレートをライセンサに順番に割当て、各スキャンレートの始点でシャッタリングを行うとともに、分割後のスキャンレート内で各ラインセンサへの露光時間を終了させるよう調整したサイクルを繰り返しながら前記ワークを撮像させる過程で、
　先行の前記撮像機と後行の前記撮像機の撮像タイミングをずらしながら交互に同一部位をオーバーラップさせる撮像サイクルを繰り返させながら前記ワークを撮像し、撮像機ごとに複数本のラインセンサにわたって取得された複数画素分の輝度値を積分遅延回路により１画素分の輝度値として記憶部に格納させる制御部と、
　前記記憶部から取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する演算処理部と、
　を備えたことを特徴とする。 Furthermore, other high-speed imaging device embodiments include:
A holding table for holding the workpiece;
An illumination unit that irradiates light toward the workpiece placed on the holding table;
An imaging unit comprising a plurality of imagers having the same plurality of line sensors for imaging the workpiece;
A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed;
According to the line sensor of the image pickup device, it is adjusted to a moving speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor, and the scan rate is equally divided according to the number of licensors of the image pickup device, A cycle in which the scan rate after division for each imaging device is assigned to the licensor in order, shuttering is performed at the start point of each scan rate, and the exposure time for each line sensor is terminated within the scan rate after division. In the process of imaging the workpiece while repeating,
The workpiece is imaged while repeating the imaging cycle in which the same part is overlapped alternately while shifting the imaging timing of the preceding imaging device and the succeeding imaging device, and acquired over a plurality of line sensors for each imaging device. A control unit that stores a luminance value for a plurality of pixels in a storage unit as a luminance value for one pixel by an integration delay circuit;
Read out the luminance values in the order obtained from the storage unit, amplify the luminance value of the pixel at the time of calculation to the luminance value before averaging, and subtract the luminance value after amplification from the luminance value of the pixel calculated immediately before An arithmetic processing unit for reconstructing an image of the workpiece based on the luminance value;
It is provided with.
　この構成によれば、制御部が、撮像機のラインセンサに応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、記撮像機の有するライセンサの本数に応じてスキャンレートを均等に分割し、撮像機ごとに分割後のスキャンレートをライセンサに順番に割当て、各スキャンレートの始点でシャッタリングを行うとともに、分割後のスキャンレート内で各ラインセンサへの露光時間を終了させるよう調整したサイクルを繰り返しながら前記ワークを撮像させる過程で、先行の前記撮像機と後行の前記撮像機の撮像タイミングをずらしながら交互に同一部位をオーバーラップさせる撮像サイクルを繰り返させながら前記ワークを撮像し、撮像機ごとに複数本のラインセンサにわたって取得された複数画素分の輝度値を積分遅延回路により１画素分の輝度値として記憶部に格納させる。したがって、上記方法の一実施形態を好適に実現することができる。 According to this configuration, the control unit adjusts the moving speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the line sensor of the image pickup device, and according to the number of licensors of the image pickup device. The scan rate is divided evenly, the divided scan rates are assigned to the licensors in order for each image pickup device, shuttering is performed at the start point of each scan rate, and exposure to each line sensor is performed within the divided scan rate. In the process of imaging the workpiece while repeating the cycle adjusted to end the time, the imaging cycle for alternately overlapping the same part while shifting the imaging timing of the preceding imaging device and the succeeding imaging device is repeated. While picking up images of the workpiece, multiple images were acquired across multiple line sensors for each imager. It is stored in the storage unit of luminance values of pixels as the luminance value of one pixel by the integral delay circuit. Therefore, an embodiment of the above method can be suitably realized.
　この構成において、撮像機は、例えば、照明ユニットから照射されてワークで反射した光または当該ワークを透過した光を導光する鏡筒部と、
　前記鏡筒部を導光する光を一部透過させるとともに、角度を変えて一部を反射させて複数台の撮像機に光を導光さる光学部材とから構成する。 In this configuration, the imaging device includes, for example, a lens barrel portion that guides light that has been irradiated from the illumination unit and reflected by the workpiece or light that has passed through the workpiece,
An optical member that partially transmits light guided through the lens barrel and reflects a part of the light by changing the angle to guide the light to a plurality of imaging devices.
　この構成によれば、同一視野から取り込まれた反射光が複数台の撮像機のラインセンサに投影されるので、位置ズレのない同一条件からワークの画像をより精度よく再構成することができる。 According to this configuration, since the reflected light taken from the same field of view is projected onto the line sensors of a plurality of imagers, the image of the workpiece can be reconstructed with higher accuracy from the same condition with no positional deviation.
　なお、上記各実施形態において複数台の前記撮像機ごとに保持テーブルとの相対的な位置を検出する検出器を備え、
　制御部は、検出器によって検出された位置情報を記憶する記憶部を備え、
　演算処理部は、撮像機ごとに取得された位置情報を前記記憶分から読み出して撮像機同士の相対的なズレ量を求め、当該ズレ量に基づいて取得画像データの位置を補正しながら画像を再構成することが好ましい。 In each of the above embodiments, a detector that detects a relative position with the holding table is provided for each of the plurality of imaging devices,
The control unit includes a storage unit that stores position information detected by the detector,
The arithmetic processing unit reads out the position information acquired for each image pickup device from the stored amount, obtains a relative shift amount between the image pickup devices, and corrects the image while correcting the position of the acquired image data based on the shift amount. It is preferable to configure.
　この構成によれば、各撮像機の位置ズレがオフセットされるので、微妙な位置調整を行う手間を省きつつ正確な位置合わせが容易にでき、画像を再構成することができる。 According to this configuration, since the positional deviation of each image pickup device is offset, accurate alignment can be easily performed and the image can be reconstructed while omitting the trouble of performing fine position adjustment.
　本発明の高速撮像方法および高速撮像装置によれば、撮像機のスキャンレートに制限されることなく、ワークの高速な撮像を可能にする。 The high-speed imaging method and high-speed imaging device of the present invention enables high-speed imaging of a workpiece without being limited by the scan rate of the imaging machine.
本実施例に係る内部検査装置の概略構成を示す斜視図である。It is a perspective view which shows schematic structure of the internal inspection apparatus which concerns on a present Example. 本実施例に係る内部検査装置の概略構成を示す正面図である。It is a front view which shows schematic structure of the internal inspection apparatus which concerns on a present Example. 高速撮像装置の撮像動作を説明するフローチャートである。It is a flowchart explaining the imaging operation of a high-speed imaging device. 撮像カメラの切り替えを示すタイミングチャートである。It is a timing chart which shows switching of an imaging camera. 実施例の撮像対象となる画像パターンを示す図である。It is a figure which shows the image pattern used as the imaging target of an Example. 画像の再構成処理を示す模式図である。It is a schematic diagram which shows the reconstruction process of an image. 変形例の撮像カメラの切り替えを示すタイミングチャートである。It is a timing chart which shows switching of the imaging camera of a modification. 変形例の撮像対象となる画像パターンを示す図である。It is a figure which shows the image pattern used as the imaging target of a modification. 変形例の画像の再構成処理を示す模式図である。It is a schematic diagram which shows the reconstruction process of the image of a modification. 変形例の撮像対象となる画像パターンを示す図である。It is a figure which shows the image pattern used as the imaging target of a modification. 変形例の第１撮像カメラの出力画像処理を示す模式図である。It is a schematic diagram which shows the output image process of the 1st imaging camera of a modification. 変形例の第２撮像カメラの出力画像処理を示す模式図である。It is a schematic diagram which shows the output image process of the 2nd imaging camera of a modification. 変形例の画像の再構成処理を示す模式図である。It is a schematic diagram which shows the reconstruction process of the image of a modification.
　以下、図面を参照して本発明の一実施例を説明する。なお、本実施例では、ワークとして表面に回路パターンの形成された半導体ウエハ（以下、単に「ウエハＷ」という）を利用し、ウエハ表面の検査用にウエハ全面を撮像する場合を例にとって説明する。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a case where a semiconductor wafer (hereinafter simply referred to as “wafer W”) having a circuit pattern formed on the surface is used as a workpiece and the entire surface of the wafer is imaged for inspection of the wafer surface will be described as an example. .
　図１は、本発明の実施例に係る高速撮像装置の概略構成を示す斜視図である。図２は、高速撮像装置の要部構成を示す正面図であり、一部に断面図を含んでいる。 FIG. 1 is a perspective view showing a schematic configuration of a high-speed imaging apparatus according to an embodiment of the present invention. FIG. 2 is a front view showing a main part configuration of the high-speed imaging device, and includes a cross-sectional view in part.
　高速撮像装置は、撮像ユニット１、検査ステージ２および制御部３などから構成されている。 The high-speed imaging device includes an imaging unit 1, an inspection stage 2, a control unit 3, and the like.
　撮像ユニット１は、鏡筒本体４、第１撮像カメラ５、第２撮像カメラ６、照明ユニット７、対物レンズ８ａ、８ｂ、８ｃおよびレボルバ９などから構成されている。 The imaging unit 1 includes a lens barrel body 4, a first imaging camera 5, a second imaging camera 6, an illumination unit 7, objective lenses 8a, 8b, 8c, a revolver 9, and the like.
　鏡筒本体４は、上方で２本に分岐されており、鏡筒のそれぞれに第１撮像カメラ５と第２撮像カメラ６が備えられている。また、鏡筒本体４の下部には、レボルバ９を介して倍率の異なる複数個の対物レンズ８ａ、８ｂを備えている。つまり、撮像視野を変更できるよう構成されている。なお、レボルバ９は、軸Ｐ周りに回転する。 The lens barrel body 4 is branched into two at the top, and a first imaging camera 5 and a second imaging camera 6 are provided in each of the lens barrels. In addition, a plurality of objective lenses 8 a and 8 b having different magnifications are provided under the lens barrel body 4 via a revolver 9. That is, the imaging field of view can be changed. The revolver 9 rotates about the axis P.
　また、鏡筒本体４の側面に照明ユニット７が装備されている。鏡筒本体４の照射ユニット７の連接部分に照射ユニット７からの光を下部のウエハＷに導くとともに、撮像ユニット１からの落射光のうちウエハＷの表面またはウエハＷを透過した裏面側から正反射する反射光（以下、適宜「観察光」という）を全透過させる第１光学部材１０が配備されている。なお、第１光学部材１０は、例えばハーフミラーまたはビームスプリッタなどが挙げられる。 Also, a lighting unit 7 is provided on the side surface of the barrel body 4. The light from the irradiation unit 7 is guided to the lower wafer W to the connection portion of the irradiation unit 7 of the lens barrel body 4, and the incident light from the imaging unit 1 is positive from the front surface of the wafer W or the back surface side that has passed through the wafer W. A first optical member 10 that totally reflects reflected light (hereinafter referred to as “observation light” as appropriate) is provided. The first optical member 10 is, for example, a half mirror or a beam splitter.
　さらに、鏡筒本体４の分岐部分には、ウエハＷからの観察光を第１撮像カメラ５および第２撮像カメラ６のそれぞれに分岐する第２光学部材１１が配備されている。なお、第２光学部材１１によって分岐された観察光は、反射ミラー１２によって全反射されて第２撮像カメラ６に導かれる。なお、第２光学部材１１は、例えばハーフミラーまたはビームスプリッタなどが挙げられる。 Furthermore, a second optical member 11 that branches the observation light from the wafer W to the first imaging camera 5 and the second imaging camera 6 is provided at a branching portion of the lens barrel body 4. Note that the observation light branched by the second optical member 11 is totally reflected by the reflection mirror 12 and guided to the second imaging camera 6. The second optical member 11 may be a half mirror or a beam splitter, for example.
　第１撮像カメラ５および第２撮像カメラ６は、同じスキャンレートのものが利用される。例えば、ＣＣＤ（charge coupled device）またはＣＭＯＳ（complementary metal oxide semiconductor）などの撮像素子を１次元配列したラインセンサ１３ａ、１３ｂをそれぞれ備えている。当該撮像素子は、観察光の輝度に応じた輝度値にデジタル変換して輝度データとして出力する。 The first imaging camera 5 and the second imaging camera 6 have the same scan rate. For example, line sensors 13a and 13b each having a one-dimensional array of image sensors such as a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor) are provided. The imaging element digitally converts the luminance value according to the luminance of the observation light and outputs the luminance data.
　検査ステージ２は、保持テーブル１４、第１可動台１５、第２可動台１６および第３可動台１７などから構成されている。 The inspection stage 2 includes a holding table 14, a first movable table 15, a second movable table 16, a third movable table 17, and the like.
　保持テーブル１４は、ウエハＷよりも大形で扁平な多孔質または金属製のチャックテーブルで構成されている。 The holding table 14 is composed of a porous or metal chuck table that is larger and flatter than the wafer W.
　保持テーブル１４の下部に配備された３台の可動台は、下から第１可動台１５、第２可動台１６および第３可動台１７の順に配備されている。第１可動台１５は、装置基台１５ｂに敷設されたガイドレール１５ｒに沿ってＹ軸方向に往復移動するスライダ１５ｓから構成されている。 The three movable platforms provided at the lower part of the holding table 14 are arranged in the order of the first movable table 15, the second movable table 16, and the third movable table 17 from the bottom. The first movable base 15 includes a slider 15s that reciprocates in the Y-axis direction along a guide rail 15r laid on the apparatus base 15b.
　第２可動台１６は、第１可動台１５のスライダ１５ｓ上に配置された基台１６ｂに敷設されたガイドレール１６ｒに沿ってＸ軸方向に往復移動するスライダ１６ｓから構成されている。 The second movable table 16 is composed of a slider 16s that reciprocates in the X-axis direction along a guide rail 16r laid on a base 16b disposed on the slider 15s of the first movable table 15.
　第３可動台１７は、第２可動台１６のスライダ１６ｓに設けられたモータ１８（例えばダイレクト・ドライブ・モータ）によってθ方向に回転する。ここで、本実施例では、Ｘ軸方向の移動を主走査方向とする。 The third movable table 17 is rotated in the θ direction by a motor 18 (for example, a direct drive motor) provided on the slider 16s of the second movable table 16. Here, in this embodiment, the movement in the X-axis direction is the main scanning direction.
　ここで、Ｙ軸方向は、ラインセンサ１３ａ、１３ｂの撮像素子の並び方向であって副走査方向とする。なお、第１可動台１５、第２可動台１６は、本発明の水平駆動機構を構成する。 Here, the Y-axis direction is the direction in which the image sensors of the line sensors 13a and 13b are arranged and is the sub-scanning direction. In addition, the 1st movable stand 15 and the 2nd movable stand 16 comprise the horizontal drive mechanism of this invention.
　制御部３は、撮像ユニット１および検査ステージ２などの動作を総括的にコントロールするとともに、内部に記憶部２０および演算処理部２１を備えている。詳細については、当該高速撮像装置の動作説明に沿って説明する。 The control unit 3 generally controls the operations of the imaging unit 1 and the inspection stage 2, and includes a storage unit 20 and an arithmetic processing unit 21 therein. Details will be described along the operation description of the high-speed imaging device.
　次に、図３のフローチャートに沿って上述の高速撮像装置を用いたウエハＷの検査画像を取得する一巡の動作について説明する。 Next, a round of operation for acquiring an inspection image of the wafer W using the above-described high-speed imaging device will be described with reference to the flowchart of FIG.
　＜ステップＳ１＞　条件設定
　まず、検査ステージ２の主走査方向である第２可動台１６のスライダ１６ｓの移動速度を決める。そうすると、第１撮像カメラ５および第２撮像カメラ６のスキャンレートによって最適移動速度Ｖ１が決まる。つまり、ラインセンサ１３ａ、１３ｂの分解能とスキャンレートによって決まる。本実施例では、所定の分解能に達する露光時間を予め実験やシミュレーションによって決める。例えば、第１撮像カメラ５と第２撮像カメラ６のスキャンレートが１０ｋＨｚで、１画素が１０μｍで、観察倍率を１０倍とした場合、第１撮像カメラ５と第２撮像カメラ６の最適移動速度Ｖ１は１０ｍｍ／ｓｅｃとなる。 <Step S1> Condition Setting First, the moving speed of the slider 16s of the second movable stage 16 that is the main scanning direction of the inspection stage 2 is determined. Then, the optimum moving speed V1 is determined by the scan rates of the first imaging camera 5 and the second imaging camera 6. That is, it is determined by the resolution and scan rate of the line sensors 13a and 13b. In this embodiment, the exposure time for reaching a predetermined resolution is determined in advance by experiments and simulations. For example, when the scan rate of the first imaging camera 5 and the second imaging camera 6 is 10 kHz, one pixel is 10 μm, and the observation magnification is 10 times, the optimum moving speed of the first imaging camera 5 and the second imaging camera 6 V1 is 10 mm / sec.
　ここで、撮像ユニット１は、主走査方向の前後に２台に第１撮像カメラ５および第２撮像カメラ６を備えているので、本実施例の場合、第２可動台１６のスライダ１６ｓの主走査速度Ｖ２を最適移動速度Ｖ１の２倍の２０ｍｍ／ｓｅｃに設定するとともに、両撮像カメラ５，６による撮像が交互に行われるように設定する。これら各条件は、制御部３の記憶部２０に記憶される。なお、第１撮像カメラ５および第２撮像カメラ６の露光時間は、分割後のスキャンレートよりも僅かに短く設定されているが、シャッタリングのタイミングが調整可能な撮像カメラを用いるものとし、当該スキャンレート内で適宜に設定変更する。つまり、シャッタリングのタイミングを調整しない状態が破線５１，６１で示すタイミングであるが、シャッタリングのタイミングを調整して露光時間を短くした状態が実線５２，６２で示すタイミングである。 Here, since the imaging unit 1 includes the first imaging camera 5 and the second imaging camera 6 before and after the main scanning direction, in the case of the present embodiment, the main of the slider 16s of the second movable table 16 is provided. The scanning speed V2 is set to 20 mm / sec, which is twice the optimum moving speed V1, and is set so that the imaging by both the imaging cameras 5 and 6 is performed alternately. Each of these conditions is stored in the storage unit 20 of the control unit 3. The exposure times of the first imaging camera 5 and the second imaging camera 6 are set slightly shorter than the scan rate after the division, but an imaging camera capable of adjusting the timing of shuttering is used. Change settings as appropriate within the scan rate. That is, the state in which the shuttering timing is not adjusted is the timing indicated by the broken lines 51 and 61, but the state in which the exposure time is shortened by adjusting the shuttering timing is the timing indicated by the solid lines 52 and 62.
　＜ステップＳ２＞　ウエハの設定
　条件設定が完了すると、搬送ロボットなどによってカセットからウエハＷを搬出し、図１に示すように、保持テーブル１４に載置する。ウエハＷは、外周領域に形成されたオリエンテーションフラットまたはＶノッチなどに基づいて位置合わせされる。すなわち、第１可動台１５および第２可動台１６を移動させて位置合わせするとともに、第３可動台１７をモータ１８の回転軸周りに回転させてウエハＷの位置合わせを行う。 <Step S2> Wafer Setting When the condition setting is completed, the wafer W is unloaded from the cassette by a transfer robot or the like, and placed on the holding table 14 as shown in FIG. The wafer W is aligned based on an orientation flat or a V notch formed in the outer peripheral region. That is, the first movable table 15 and the second movable table 16 are moved and aligned, and the third movable table 17 is rotated around the rotation axis of the motor 18 to align the wafer W.
　＜ステップＳ３＞　撮像開始
　ウエハＷのアライメント処理と撮像開始の初期位置への移動が完了すると、撮像ユニット１を所定高さに移動および設定した後に、第２可動台１６のスライダ１６ｓの主走査速度Ｖ２をＸ軸方向に最適移動速度Ｖ１の２倍の速度で走査させながらウエハＷの撮像を開始する。撮像開始と同時に、図４に示すように、制御部３から第１撮像カメラ５にトリガ信号１が送信されると、それを受けて第１撮像カメラ５のシャッターがＯＮ状態となり撮像が開始され、観察光がラインセンサ１３ａに露光される。また、制御部３から第２撮像カメラ６にトリガ信号２が送信されると、それを受けて第２撮像カメラ６のシャッターがＯＮ状態となり撮像が開始され、観察光がラインセンサ１３ｂに露光される。このとき、トリガ信号１とトリガ信号２はそれぞれ交互に出力するようにしておく。さらに、第１撮像カメラ５と第２撮像カメラ６は、上述したようにシャッタリング時間を通常（つまり、破線５１，６１で示す状態）の半分（つまり、実線５２，６２で示す状態）に設定しておく。 <Step S3> Start of Imaging When the alignment processing of the wafer W and the movement to the initial position of the imaging start are completed, the main scanning speed of the slider 16s of the second movable table 16 is moved after the imaging unit 1 is moved and set to a predetermined height. Imaging of the wafer W is started while scanning V2 in the X-axis direction at twice the optimum moving speed V1. Simultaneously with the start of imaging, as shown in FIG. 4, when the trigger signal 1 is transmitted from the control unit 3 to the first imaging camera 5, the shutter of the first imaging camera 5 is received and imaging is started. The observation light is exposed to the line sensor 13a. Further, when the trigger signal 2 is transmitted from the control unit 3 to the second imaging camera 6, the shutter of the second imaging camera 6 is turned on in response thereto, imaging is started, and observation light is exposed to the line sensor 13 b. The At this time, the trigger signal 1 and the trigger signal 2 are alternately output. Further, as described above, the first imaging camera 5 and the second imaging camera 6 set the shuttering time to half of the normal (that is, the state indicated by the broken lines 51 and 61) (that is, the state indicated by the solid lines 52 and 62). Keep it.
　第１撮像カメラ５および第２撮像カメラ６は、シャッタリング時間を短く設定しても、通常のシャッタリング時間経過後に画像データを出力されるよう構成されていることが一般的である。そのため、両撮像カメラ５，６からの出力信号は、破線５１，６１で示されたＯＦＦ状態となった後に、輝度データ１ａ、１ｂ…および輝度データ２ａ、２ｂ…のように、両撮像カメラ４，６から交互に出力される。そうすることで、ワークを２倍の速度で移動させつつ、２台の撮像カメラ５，６を用いて、見かけ上２倍のスキャンレートで撮像が行われることとなる。 The first imaging camera 5 and the second imaging camera 6 are generally configured to output image data after the normal shuttering time has elapsed even if the shuttering time is set short. Therefore, after the output signals from both the imaging cameras 5 and 6 are in the OFF state indicated by the broken lines 51 and 61, both the imaging cameras 4 are represented as the luminance data 1a, 1b... And the luminance data 2a, 2b. , 6 are alternately output. By doing so, imaging is performed at an apparently double scan rate using the two imaging cameras 5 and 6 while moving the workpiece at twice the speed.
　図５は、撮像対象となる画像パターンであり、マトリクス状に分割された画像パターンの輝度値（９０）が示されている。ここで空白の部分は、輝度値が０であることを意味している。また、縦軸は撮像する時刻：ｔ０～ｔ１６、横軸は撮像に用いるラインセンサのアドレス（１～１６）を例示している。また、図中右側には、第１撮像カメラ５と第２撮像カメラ６のシャッターがＯＮ状態となっているタイミング（ｔ１ａ～ｔ８ａ、ｔ１ｂ～ｔ８ｂ）が、併せて示されている。つまり、時刻ｔ２のときに、ラインセンサのアドレス８，９において、第１撮像カメラ５を用いて、シャッターＯＮとなるタイミングｔ２ａで輝度９０部分の撮像が行われる。同様に、時刻ｔ３のときに、ラインセンサのアドレス７，１０において、第２撮像カメラ６を用いて、シャッターＯＮとなるタイミングｔ２ｂで輝度９０部分の撮像が行われる。そして、上記一連の連続撮像処理を１サイクルとし、ウエハＷの一端から他端まで走査される間に当該サイクルを繰り返しながら両撮像カメラ５、６によってウエハＷが撮像される。 FIG. 5 shows an image pattern to be imaged, and the luminance value (90) of the image pattern divided into a matrix is shown. Here, the blank portion means that the luminance value is zero. Further, the vertical axis shows the time of imaging: t0 to t16, and the horizontal axis shows the address (1 to 16) of the line sensor used for imaging. Further, on the right side of the figure, timings (t1a to t8a, t1b to t8b) at which the shutters of the first imaging camera 5 and the second imaging camera 6 are turned on are also shown. That is, at time t2, at the address 8 and 9 of the line sensor, the first imaging camera 5 is used to capture 90 luminance portions at the timing t2a when the shutter is turned on. Similarly, at time t3, at the address 7 and 10 of the line sensor, the second imaging camera 6 is used to capture 90 luminance portions at the timing t2b when the shutter is turned on. The series of continuous imaging processes is defined as one cycle, and the wafer W is imaged by both imaging cameras 5 and 6 while repeating the cycle while scanning from one end of the wafer W to the other end.
　＜ステップＳ４＞　画像再構成処理
　上記一連の連続撮像処理サイクルを行って画像を撮像し、後に画像再構築をする処理について説明する。 <Step S4> Image Reconstruction Processing Processing for performing image reconstruction by performing the above-described series of continuous imaging processing cycles and then image reconstruction will be described.
　図６（ａ）は、第１撮像カメラ５から出力される輝度データであり、図６（ｂ）は、第２撮像カメラ６から出力される輝度データである。上述の連続撮像処理サイクルが繰り返されると、図４や図５で示すように、第１撮像カメラ５と第２撮像カメラ６の撮像タイミング及びデータ出力タイミングは交互に行われる。そのため、図６（ａ）に示すように、第１撮像カメラ５から、シャッターＯＮとなるタイミングｔ１ａ～ｔ８ａで撮像した画像に対応するデータ出力タイミング（つまり、時刻ｄ１ａ～ｄ８ａ）で、それぞれ輝度データが出力される。また、図６（ｂ）に示すように、第２撮像カメラ６から、シャッターＯＮとなるタイミングｔ１ｂ～ｔ８ｂで撮像した画像に対応するデータ出力タイミング（つまり、時刻ｄ１ｂ～ｄ８ｂ）で、それぞれ輝度データが出力される。 6A shows luminance data output from the first imaging camera 5, and FIG. 6B shows luminance data output from the second imaging camera 6. When the above-described continuous imaging process cycle is repeated, the imaging timing and the data output timing of the first imaging camera 5 and the second imaging camera 6 are alternately performed as shown in FIGS. Therefore, as shown in FIG. 6A, the luminance data is respectively output from the first imaging camera 5 at the data output timings corresponding to the images captured at the timings t1a to t8a when the shutter is turned on (that is, the times d1a to d8a). Is output. Further, as shown in FIG. 6B, the luminance data is respectively output from the second imaging camera 6 at the data output timing corresponding to the image captured at the timing t1b to t8b when the shutter is turned on (that is, the times d1b to d8b). Is output.
なお、両撮像カメラ５，６から出力される信号は、Ａ／Ｄ変換されて輝度値として第１撮像カメラ５および第２撮像カメラ６ごとに分けて記憶部２０に記憶されている。 The signals output from both the imaging cameras 5 and 6 are A / D converted and stored in the storage unit 20 as brightness values separately for each of the first imaging camera 5 and the second imaging camera 6.
　演算処理部２１は、記憶部２０から両撮像カメラ５、６の輝度値を読み出し、読み出した輝度値を交互に古い方から順に並べて図６（ｃ）に示すように合成し、ウエハＷの全体画像の再構成処理をする。なお、上述したように両カメラ５，６の露光時間を通常の半分に設定したので、記憶部２０に記憶されている輝度値は本来の値の半分（４５）となっている。そのため、画像再構成処理を行う際は、このことを考慮して、輝度値を２倍した値（９０）に演算する処理も併せて行う。 The arithmetic processing unit 21 reads the luminance values of the two imaging cameras 5 and 6 from the storage unit 20, and alternately arranges the read luminance values in order from the oldest one as shown in FIG. Reconstruct the image. As described above, since the exposure time of both cameras 5 and 6 is set to half of the normal value, the luminance value stored in the storage unit 20 is half the original value (45). Therefore, when performing the image reconstruction process, in consideration of this, a process of calculating a value (90) obtained by doubling the luminance value is also performed.
　＜ステップＳ５＞　ウエハ搬出
　ウエハＷの撮像が完了すると、搬送ロボットなどによってウエハＷを吸着し、図示しないカセットにウエハＷを搬送する。以上で一連の検査画像を取得する処理が完了し、以後、同じ処理が繰り返される（ステップＳ６）。 <Step S5> Wafer Unloading When the imaging of the wafer W is completed, the wafer W is sucked by a transfer robot or the like and transferred to a cassette (not shown). This completes the process of acquiring a series of inspection images, and thereafter the same process is repeated (step S6).
　走査方向の前後に配備した２台の第１撮像カメラ５および第２撮像カメラ６を利用しつ　走査方向の前後に配備した２台の第１撮像カメラ５および第２撮像カメラ６を利用しつつ移動速度を撮像カメラの台数の２倍に設定しただけでは、１台の撮像カメラで連続的にウエハＷの全面を撮像できない。しかしながら、上記実施例装置によれば、スキャンレートを撮像カメラの台数に応じて２等分にしたタイミングで各撮像カメラ５、６の撮像を交互に切り替え、さらに露光時間を半分に設定することにより、第１撮像カメラ５および第２撮像カメラ６のそれぞれの露光時間が半分になりつつも、ウエハ全体の画像が途切れることなく、連続した画像データを取得することができる。したがって、取得した画像データ（輝度値）の基づいて単純に合成するだけでウエハＷの全体画像を容易に再構成することができる。すなわち、撮像カメラの最適移動速度Ｖ１を超えた２倍の速度Ｖ２速度であっても、ウエハＷの画像を容易かつ精度よく取得することができるので、検査工程のスループットを高めることができる。 Using the two first imaging cameras 5 and the second imaging cameras 6 arranged before and after the scanning direction, while using the two first imaging cameras 5 and the second imaging cameras 6 arranged before and after the scanning direction If the moving speed is set to twice the number of imaging cameras, the entire surface of the wafer W cannot be continuously imaged by one imaging camera. However, according to the above-described embodiment apparatus, by alternately switching the imaging of the imaging cameras 5 and 6 at the timing when the scan rate is divided into two according to the number of imaging cameras, and further setting the exposure time in half. While the exposure time of each of the first imaging camera 5 and the second imaging camera 6 is halved, continuous image data can be acquired without interruption of the entire wafer image. Therefore, the entire image of the wafer W can be easily reconstructed by simply synthesizing based on the acquired image data (luminance value). That is, since the image of the wafer W can be acquired easily and accurately even at a speed V2 that is twice the optimum moving speed V1 of the imaging camera, the throughput of the inspection process can be increased.
　本発明は上述した実施例のものに限らず、次のように変形実施することもできる。 The present invention is not limited to the embodiment described above, and can be modified as follows.
　（１）上記実施例の装置および方法において、第１撮像カメラ５および第２撮像カメラ６の露光時間を短く設定できないものがある。しかし、その様な撮像カメラを用いた場合でも、以下に述べる手段によって、本発明の目的を達成することができる。つまり、上述したステップＳ３，Ｓ４に替えて、以下の処理ステップＳ３’，Ｓ４’を行うことにより具現化できる。 (1) In the apparatus and method of the above-described embodiment, there are some apparatuses in which the exposure time of the first imaging camera 5 and the second imaging camera 6 cannot be set short. However, even when such an imaging camera is used, the object of the present invention can be achieved by the means described below. That is, it can be realized by performing the following processing steps S3 'and S4' instead of the above-described steps S3 and S4.
　＜ステップＳ３’＞　撮像開始
　ウエハＷのアライメント処理と撮像開始の初期位置への移動が完了すると、撮像ユニット１を所定高さに移動および設定した後に、第２可動台１６のスライダ１６ｓの主走査速度Ｖ２をＸ軸方向に最適移動速度Ｖ１の２倍の速度で走査させながらウエハＷの撮像を開始する。撮像開始と同時に、図７に示すように、制御部３から第１撮像カメラ５にトリガ信号１が送信されると、それを受けて第１撮像カメラ５のシャッターがＯＮ状態となり撮像が開始され、観察光がラインセンサ１３ａに露光される。また、制御部３から第２撮像カメラ６にトリガ信号２が送信されると、それを受けて第２撮像カメラ６のシャッターがＯＮ状態となり撮像が開始され、観察光がラインセンサ１３ｂに露光される。このとき、トリガ信号１とトリガ信号２はそれぞれ交互に出力するようにしておく。なお、第１撮像カメラ５と第２撮像カメラ６は、シャッタリング時間は通常の状態（つまり、実線５３，６３で示す状態）であり、交互に同一部位をオーバーラップしながら撮像を行っている。また、上記ステップＳ３と同様に、ワークを２倍の速度で移動させつつ、２台の撮像カメラ５，６を用いて、見かけ上２倍のスキャンレートで撮像が行われる。 <Step S3 ′> Imaging Start When the alignment processing of the wafer W and the movement to the initial position of the imaging start are completed, the imaging unit 1 is moved and set to a predetermined height, and then the main scanning of the slider 16s of the second movable table 16 is performed. Imaging of the wafer W is started while scanning the speed V2 in the X-axis direction at twice the optimum moving speed V1. Simultaneously with the start of imaging, as shown in FIG. 7, when the trigger signal 1 is transmitted from the control unit 3 to the first imaging camera 5, the shutter of the first imaging camera 5 is turned on and imaging is started. The observation light is exposed to the line sensor 13a. Further, when the trigger signal 2 is transmitted from the control unit 3 to the second imaging camera 6, the shutter of the second imaging camera 6 is turned on in response thereto, imaging is started, and observation light is exposed to the line sensor 13 b. The At this time, the trigger signal 1 and the trigger signal 2 are alternately output. The first imaging camera 5 and the second imaging camera 6 have a normal shuttering time (that is, a state indicated by solid lines 53 and 63), and perform imaging while alternately overlapping the same part. . Similarly to step S3, imaging is performed at an apparently double scan rate using the two imaging cameras 5 and 6 while moving the workpiece at a double speed.
　図８は、撮像対象となる画像パターンであり、マトリクス状に分割された画像パターンの輝度値（９０）が示されている。ここで空白の部分は、輝度値が０であることを意味している。また、縦軸は撮像する時刻：ｔ０～ｔ１６、横軸は撮像に用いるラインセンサのアドレス（１～１６）を例示している。また、図中右側には、第１撮像カメラ５と第２撮像カメラ６のシャッターがＯＮ状態となっているタイミング（ｔ１ａ～ｔ８ａ、ｔ１ｂ～ｔ８ｂ）が、併せて示されている。つまり、時刻ｔ２～ｔ３にかけて、ラインセンサのアドレス８，９において、第１撮像カメラ５を用いて、シャッターＯＮとなるタイミングｔ２ａで輝度９０部分の撮像が行われる。同様に、時刻ｔ３～ｔ４にかけて、ラインセンサのアドレス７，１０において、第２撮像カメラ６を用いて、シャッターＯＮとなるタイミングｔ２ｂで輝度９０部分の撮像が行われる。そして、上記一連の連続撮像処理を１サイクルとし、ウエハＷの一端から他端まで走査される間に当該サイクルを繰り返しながら両撮像カメラ５、６によってウエハＷが撮像される。 FIG. 8 shows an image pattern to be imaged, and the luminance value (90) of the image pattern divided into a matrix is shown. Here, the blank portion means that the luminance value is zero. Further, the vertical axis shows the time of imaging: t0 to t16, and the horizontal axis shows the address (1 to 16) of the line sensor used for imaging. Further, on the right side of the figure, timings (t1a to t8a, t1b to t8b) at which the shutters of the first imaging camera 5 and the second imaging camera 6 are turned on are also shown. In other words, from time t2 to time t3, at the line sensor addresses 8 and 9, the first imaging camera 5 is used to capture 90 luminance portions at the timing t2a when the shutter is turned on. Similarly, from time t3 to t4, at the address 7 and 10 of the line sensor, the second imaging camera 6 is used to capture the 90 brightness portion at the timing t2b when the shutter is turned on. The series of continuous imaging processes is defined as one cycle, and the wafer W is imaged by both imaging cameras 5 and 6 while repeating the cycle while scanning from one end of the wafer W to the other end.
　＜ステップＳ４’＞　画像再構成処理
　上記一連の連続撮像処理サイクルを行って画像を撮像し、後に画像再構築をする処理について説明する。 <Step S4 ′> Image Reconstruction Process A process for capturing an image by performing the above-described series of continuous imaging process cycles and then reconstructing the image will be described.
　図９（ａ）は、第１撮像カメラ５から出力される輝度データであり、図９（ｂ）は、第２撮像カメラ６から出力される輝度データである。 9A shows luminance data output from the first imaging camera 5, and FIG. 9B shows luminance data output from the second imaging camera 6.
　上述の連続撮像処理サイクルが繰り返されると、図７や図８で示すように、第１撮像カメラ５と第２撮像カメラ６の撮像タイミングおよびデータ出力タイミングは交互に行われる。そのため、図９（ａ）に示すように、第１撮像カメラ５から、シャッターＯＮとなるタイミングｔ１ａ～ｔ８ａで撮像した画像に対応するデータ出力タイミング（つまり、時刻ｄ１ａ～ｄ８ａ）で、それぞれ輝度データが出力される。また、図９（ｂ）に示すように、第２撮像カメラ６から、シャッターＯＮとなるタイミングｔ１ｂ～ｔ８ｂで撮像した画像に対応するデータ出力タイミング（つまり、時刻ｄ１ｂ～ｄ８ｂ）で、それぞれ輝度データが出力される。（ここまでは、ステップＳ４と同様である）。なお、両撮像カメラ５，６から出力される信号は、Ａ／Ｄ変換されて輝度値として第１撮像カメラ５および第２撮像カメラ６ごとに分けて記憶部２０に記憶されているが、シャッター時間が長く２画素に渡って撮像が行われるため、２画素分が平均化され輝度値が格納されることになる。そこで、２つのカメラで取得された輝度値が、それぞれ時系列的に平均化されたものであることと、他方のカメラでもオーバーラップして取得されていることを考慮し、下記の手順に基づいて画像再構成処理を行う（これらは、上記ステップＳ４と相違する）。 When the above-described continuous imaging process cycle is repeated, the imaging timing and the data output timing of the first imaging camera 5 and the second imaging camera 6 are alternately performed as shown in FIGS. Therefore, as shown in FIG. 9A, the luminance data is respectively output from the first imaging camera 5 at the data output timings corresponding to the images captured at the timings t1a to t8a when the shutter is turned on (that is, the times d1a to d8a). Is output. Further, as shown in FIG. 9B, the luminance data is respectively output from the second imaging camera 6 at the data output timing corresponding to the image captured at the timing t1b to t8b when the shutter is turned on (that is, the times d1b to d8b). Is output. (The steps so far are the same as in step S4). The signals output from both the imaging cameras 5 and 6 are A / D converted and stored in the storage unit 20 as brightness values separately for each of the first imaging camera 5 and the second imaging camera 6. Since imaging is performed over two pixels for a long time, the two pixels are averaged and the luminance value is stored. Therefore, based on the following procedure, taking into account that the luminance values acquired by the two cameras are averaged in time series and also acquired by the other camera in an overlapping manner. Then, image reconstruction processing is performed (these are different from step S4).
　まず、この設定条件で第１撮像カメラ５と第２撮像カメラ６の撮像を交互に繰り返して行って画像データを取得した場合、トリガ信号を受けた現時点の撮像カメラが撮像を開始した前半の露光時間内の出力信号と先行する撮像カメラの後半の露光時間の出力信号がオーバーラップして出力される。両出力信号に基づいて求めた輝度値は、先行して取得さるべき輝度値が合成された測定輝度値として記憶部２０に記憶される。 First, when image data is acquired by alternately repeating imaging with the first imaging camera 5 and the second imaging camera 6 under these setting conditions, the first half of exposure when the current imaging camera receiving the trigger signal starts imaging. The output signal within the time and the output signal of the second half exposure time of the preceding imaging camera overlap and are output. The luminance value obtained based on both output signals is stored in the storage unit 20 as a measured luminance value obtained by combining the luminance values to be acquired in advance.
　そこで、演算処理部２１は、記憶部２０から読み出した両撮像カメラ５、６の輝度値をそれぞれ交互に古い方から順に並べつつ、読み出した輝度値（Ｂ）を２倍した値（２Ｂ）から、直前の画素の輝度値（Ａ）を減算した値（Ｃ＝Ａ－２Ｂ）を演算して求める処理を行う。なお、第１列目の輝度値（Ｂ）に対する直前の画素の輝度値（Ａ）は、０をあてはめて処理を開始する。 Therefore, the arithmetic processing unit 21 arranges the luminance values of the two imaging cameras 5 and 6 read from the storage unit 20 alternately in order from the oldest one, and doubles the read luminance value (B) from the value (2B). Then, a process of calculating and obtaining a value (C = A−2B) obtained by subtracting the luminance value (A) of the immediately preceding pixel is performed. Note that the luminance value (A) of the pixel immediately before the luminance value (B) in the first column is set to 0 to start processing.
　例えば、アドレス８，９について説明すると、以下のようになる。まず、第１撮像カメラ５にて時刻ｔ１ａで撮像された画像は、時刻ｄ１ａで輝度値（Ｂ）が０として出力される。また、この場所の輝度値（Ｃ）は、直前の画素の輝度値（Ａ）が０をあてはめられている。そのため、時刻ｄ１ａのアドレス８，９に対応する部分は、輝度値０と算出される。続いて、第２撮像カメラ６にて時刻ｔ１ｂで撮像された画像は、時刻ｄ１ｂで輝度値（Ｂ）が４５として出力される。また、この場所の輝度値（Ｃ）は、直前の画素の輝度値（Ａ）が０と算出されている。そのため、時刻ｄ１ｂのアドレス８，９に対応する部分は、輝度値９０と算出される。 For example, addresses 8 and 9 will be described as follows. First, an image captured at time t1a by the first imaging camera 5 is output with a luminance value (B) of 0 at time d1a. Further, the luminance value (C) of this place is set to 0 as the luminance value (A) of the immediately preceding pixel. Therefore, the portion corresponding to the addresses 8 and 9 at the time d1a is calculated as the luminance value 0. Subsequently, the image captured at the time t1b by the second imaging camera 6 is output with a luminance value (B) of 45 at the time d1b. In addition, the luminance value (A) of the immediately preceding pixel is calculated as 0 as the luminance value (C) of this place. Therefore, the portion corresponding to the addresses 8 and 9 at the time d1b is calculated as the luminance value 90.
　続いて、第１撮像カメラ５にて時刻ｔ２ａで撮像された画像は、時刻ｄ２ａで輝度値（Ｂ）が４５として出力される。また、この場所の輝度値（Ｃ）は、直前の画素の輝度値（Ａ）が９０をあてはめられている。そのため、時刻ｄ２ａのアドレス８，９に対応する部分は、輝度値０と算出される。同様の処理を、全てのアドレスについても、逐次連続的に行うことで、図９（ｃ）に示すようなウエハＷの全体の輝度値を示す、全体画像として再構成できる。 Subsequently, the image captured at time t2a by the first imaging camera 5 is output with a luminance value (B) of 45 at time d2a. In addition, the luminance value (C) of the previous pixel is set to 90 as the luminance value (A) of the immediately preceding pixel. Therefore, the portion corresponding to the addresses 8 and 9 at the time d2a is calculated as the luminance value 0. By performing the same processing for all the addresses sequentially and continuously, it can be reconstructed as an entire image showing the entire luminance value of the wafer W as shown in FIG.
　以上のように、露光時間を調整できない安価な撮像カメラであっても、２台の撮像カメラを用いることで、上記メイン実施例と同様に、撮像カメラのスキャンレートに制限されず、最適移動速度Ｖ１を超えた２倍の速度Ｖ２での撮像を実現することができる。 As described above, even with an inexpensive imaging camera in which the exposure time cannot be adjusted, by using two imaging cameras, similarly to the above-described main embodiment, the scanning speed of the imaging camera is not limited, and the optimum moving speed is achieved. It is possible to realize imaging at twice the speed V2 exceeding V1.
　（２）上記実施例の装置および方法において、第１撮像カメラ５および第２撮像カメラ６は、複数本のラインセンサを備えた構成であってもよい。この場合、主走査方向の前後にラインセンサを隣接配備するように構成し、それぞれのラインセンサで取得した同一アドレスの輝度値を、時間遅延積分処理（いわゆるＴＤＩ（Time Delay integration）処理）をするように構成しておく。この構成は、別体のラインセンサ複数本とＴＤＩ回路とを組み合わせて具現化してもよいし、一般に入手可能ないわゆるＴＤＩカメラ（上記構成が一体となっているもの）を用いてもよい。 (2) In the apparatus and method of the above embodiment, the first imaging camera 5 and the second imaging camera 6 may be configured to include a plurality of line sensors. In this case, line sensors are arranged adjacently before and after in the main scanning direction, and the luminance value at the same address acquired by each line sensor is subjected to time delay integration processing (so-called TDI (Time Delay Integration) processing). It is configured as follows. This configuration may be realized by combining a plurality of separate line sensors and a TDI circuit, or a commonly available so-called TDI camera (one in which the above configuration is integrated) may be used.
　この構成の場合、ラインセンサ自体のスキャンレートが、上記実施例と同じく、ワークの移動速度が最適移動速度Ｖ１であれば、複数のセンサで取得された輝度値を時間遅延積分処理して、高感度撮像が実現できる。そのため、ワークの輝度値が低い場合、このような形態のカメラを用いて検査することが好ましい。しかしながら、ワークの移動速度が、最適移動速度Ｖ１と一致しない場合、時間遅延積分処理のタイミングが合わず、所定の取得画像データが得られない。そこで本発明に係る変形例では、ＴＤＩカメラを用いた場合、上述したステップＳ３’に代えて、下述のステップＳ３”を行う。 In the case of this configuration, if the scanning speed of the line sensor itself is the optimum moving speed V1 as in the above embodiment, the luminance values acquired by a plurality of sensors are subjected to time delay integration processing, Sensitivity imaging can be realized. Therefore, when the brightness value of the workpiece is low, it is preferable to inspect using such a camera. However, when the moving speed of the workpiece does not coincide with the optimum moving speed V1, the timing of the time delay integration process does not match and predetermined acquired image data cannot be obtained. Therefore, in the modification according to the present invention, when a TDI camera is used, the following step S3 ″ is performed instead of the above-described step S3 ′.
　＜ステップＳ３”＞　撮像開始
　ウエハＷのアライメント処理と撮像開始の初期位置への移動が完了すると、撮像ユニット１を所定高さに移動および設定した後に、第２可動台１６のスライダ１６ｓの主走査速度Ｖ２をＸ軸方向に最適移動速度Ｖ１の２倍の速度に設定して走査させながらウエハＷの撮像を開始する。このとき、第１撮像カメラ５と第２撮像カメラ６は、例えば、主走査方向に４列のラインセンサと時間遅延積分処理回路とを備えたＴＤＩカメラを用いて構成しておく。 <Step S3 ″> Imaging start When the alignment processing of the wafer W and the movement to the initial position of the imaging start are completed, the imaging unit 1 is moved and set to a predetermined height, and then the main scanning of the slider 16s of the second movable table 16 is performed. The imaging of the wafer W is started while scanning with the speed V2 set to twice the optimum moving speed V1 in the X-axis direction At this time, the first imaging camera 5 and the second imaging camera 6 are, for example, main It is configured using a TDI camera provided with four lines of line sensors and a time delay integration processing circuit in the scanning direction.
　また、上述の変形例（１）と同様に、制御部３から第１撮像カメラ５と第２撮像カメラ６に対して、トリガ信号１とトリガ信号２が交互に送信されるように構成しておく。また、第１撮像カメラ５と第２撮像カメラ６が、交互に同一部位をオーバーラップしながら撮像を行うように構成しておく。そして、ワークを主走査速度Ｖ２で移動させつつ、２台の撮像カメラ５，６を用いて、撮像を行う。 Similarly to the above-described modification (1), the trigger signal 1 and the trigger signal 2 are alternately transmitted from the control unit 3 to the first imaging camera 5 and the second imaging camera 6. deep. In addition, the first imaging camera 5 and the second imaging camera 6 are configured to perform imaging while alternately overlapping the same part. Then, imaging is performed using the two imaging cameras 5 and 6 while moving the workpiece at the main scanning speed V2.
　図１０は、撮像対象となる画像パターンであり、マトリクス状に分割された画像パターンの輝度値（２０）が示されている。ここで空白の部分は、輝度値が０であることを意味している。また、縦軸は撮像する時刻：ｔ０～ｔ１６、横軸は撮像に用いるラインセンサのアドレス（１～１６）を例示している。 FIG. 10 shows an image pattern to be imaged, and the luminance value (20) of the image pattern divided into a matrix is shown. Here, the blank portion means that the luminance value is zero. Further, the vertical axis shows the time of imaging: t0 to t16, and the horizontal axis shows the address (1 to 16) of the line sensor used for imaging.
　両撮像カメラ５、６ごとに分けて測定輝度値に基づいて画像を構成すると、次のようになる。例えば、第１撮像カメラ５は、時刻ｔ３では図１１（ａ）に示す位置にあり、時刻ｔ５では図１１（ｂ）に示す位置にある。そして、時刻ｔ２～ｔ３にかけて第１ラインセンサ群を用いて撮像・取得した前段の輝度データは、ＴＤＩ処理にて後段に送られ、時刻ｔ４～ｔ５にかけて第２ラインセンサ群を用いて撮像・取得した後段の輝度データと積算処理がされる。そして、所定段数（上記例では２段）分の積算された値が、時刻ｄ２ａで１回の撮像分の輝度データとして外部に出力される。そして、複数回分の撮像の出力信号に基づいて画像を構成すると、図１１（ｃ）に示すように、輝度値の重複した部分が生じる。 When an image is constructed based on the measured luminance value separately for each of the imaging cameras 5 and 6, the following is obtained. For example, the first imaging camera 5 is at the position shown in FIG. 11A at time t3 and at the position shown in FIG. 11B at time t5. Then, the luminance data of the previous stage captured and acquired using the first line sensor group from time t2 to t3 is sent to the subsequent stage by TDI processing, and imaged and acquired using the second line sensor group from time t4 to t5. The subsequent luminance data and integration processing are performed. Then, the integrated value for a predetermined number of steps (two in the above example) is output to the outside as luminance data for one imaging at time d2a. When an image is constructed based on the output signals of a plurality of times of imaging, as shown in FIG.
　一方、第２撮像カメラ６は、第１撮像カメラ５の撮像位置と主走査方向に１画素分ずれた場所を観察するように取り付けられている。そのため、第２撮像カメラ６は、時刻ｔ４では図１２（ａ）に示す位置を観察し、時刻ｔ６では図１２（ｂ）に示す位置を観察することになる。そして、時刻ｔ３～ｔ４にかけて第１ラインセンサ群を用いて撮像・取得した前段の輝度データは、ＴＤＩ処理にて後段に送られ、時刻ｔ５～ｔ６にかけて第２ラインセンサ群を用いて撮像・取得した後段の輝度データと積算処理がされる。そして、所定段数（上記例では２段）分の積算された値が、時刻ｄ２ｂで１回の撮像分の輝度データとして外部に出力される。そして、複数回分の撮像の出力信号に基づいて画像を構成すると、図１２（ｃ）に示すように輝度値の重複した部分が生じる。 On the other hand, the second imaging camera 6 is attached so as to observe a position shifted by one pixel in the main scanning direction from the imaging position of the first imaging camera 5. Therefore, the second imaging camera 6 observes the position shown in FIG. 12A at time t4 and observes the position shown in FIG. 12B at time t6. Then, the previous luminance data captured and acquired using the first line sensor group from time t3 to t4 is sent to the subsequent stage in the TDI processing, and imaged and acquired using the second line sensor group from time t5 to t6. The subsequent luminance data and integration processing are performed. Then, the integrated values for a predetermined number of steps (two in the above example) are output to the outside as luminance data for one imaging at time d2b. Then, when an image is constructed based on the output signals of a plurality of times of imaging, a portion where luminance values overlap is generated as shown in FIG.
　当該測定輝度値からウエハＷの画像を再構成するとき、演算処理部２１は、上記変形例（１）と同様の画像再構成処理を行うことで、所望の全体画像として再構成することができる。しかも、複数のラインセンサと用いてＴＤＩ処理を行っていることで、図１３に示すような、輝度値を増幅させた画像データを取得することができる。 When reconstructing the image of the wafer W from the measured luminance value, the arithmetic processing unit 21 can reconstruct a desired whole image by performing the image reconstruction process similar to the modification (1). . Moreover, by performing TDI processing using a plurality of line sensors, it is possible to acquire image data obtained by amplifying the luminance value as shown in FIG.
　この構成によれば、１本のラインセンサを備えた撮像カメラで構成した撮像ユニットを用いた場合よりも高感度でワークを撮像することができる。 According to this configuration, a workpiece can be imaged with higher sensitivity than when an imaging unit configured with an imaging camera including a single line sensor is used.
　（３）上記実施例の装置および方法において、第１撮像カメラ５および第２撮像カメラ６ごとに保持テーブル１４との相対的な位置関係をセンサまたはそれぞれの撮像カメラの予備撮像を通じて得た位置関係から撮像カメラ同士の相対的なズレ量を求め、当該ズレ量に応じて画像を補正してもよい。 (3) In the apparatus and method of the above embodiment, the relative positional relationship with the holding table 14 for each of the first imaging camera 5 and the second imaging camera 6 is obtained by the sensor or the preliminary imaging of each imaging camera. Thus, the relative shift amount between the imaging cameras may be obtained, and the image may be corrected according to the shift amount.
　（４）上記実施例の装置および方法では、撮像ユニット１に２台の第１撮像カメラ５および第２撮像カメラ６を備えた構成であったが、当該台数に限定されない。すなわち、撮像カメラは、２台以上であればよい。この場合、撮像カメラの台数を増やすごとに第２可動台１６の移動速度を高速にすることができる。例えば、最適移動速度Ｖ１×撮像カメラの台数に設定し、第２可動台１６のスライダ１６ｓを移動させる。また、スキャンレートを台数分に均等に分割し、当該分割したタイミングで交互に撮像するとともに、撮像タイミングを切り替えるまでの時間をそれぞれの撮像カメラの露光時間に設定すればよい。 (4) In the apparatus and method of the above embodiment, the imaging unit 1 includes the two first imaging cameras 5 and the second imaging camera 6, but the number is not limited thereto. That is, the number of imaging cameras may be two or more. In this case, the moving speed of the second movable table 16 can be increased every time the number of imaging cameras is increased. For example, the optimal moving speed V1 × the number of imaging cameras is set, and the slider 16s of the second movable base 16 is moved. Further, the scan rate is equally divided into the number of the images, the images are alternately captured at the divided timing, and the time until the imaging timing is switched may be set as the exposure time of each imaging camera.
　また、ＴＤＩカメラを使う形態においても、主走査方向に並列されるラインセンサの数やビニングする画素数（段数）は、設定する主走査速度や所望の増感度合いに応じて適宜設定するものとする。 Also in the form using a TDI camera, the number of line sensors arranged in parallel in the main scanning direction and the number of pixels to be binned (the number of stages) are appropriately set according to the main scanning speed to be set and the desired sensitivity enhancement. To do.
　　１　…　撮像ユニット
　　２　…　検査ステージ
　　３　…　制御部
　　４　…　鏡筒本体
　　５　…　第１撮像カメラ
　　６　…　第２撮像カメラ
　　７　…　照明ユニット
　１３ａ…　ラインセンサ（第１撮像カメラ用）
　１３ｂ…　ラインセンサ（第２撮像カメラ用）
　１４　…　保持テーブル
　１５　…　第１可動台
　１６　…　第２可動台
　１７　…　第３可動台
　２０　…　記憶部
　２１　…　演算処理部 DESCRIPTION OF SYMBOLS 1 ... Imaging unit 2 ... Inspection stage 3 ... Control part 4 ... Lens-barrel body 5 ... 1st imaging camera 6 ... 2nd imaging camera 7 ... Illumination unit 13a ... Line sensor (for 1st imaging camera)
13b ... Line sensor (for second imaging camera)
DESCRIPTION OF SYMBOLS 14 ... Holding table 15 ... 1st movable stand 16 ... 2nd movable stand 17 ... 3rd movable stand 20 ... Memory | storage part 21 ... Arithmetic processing part

Claims (9)

  1. 　ワークを撮像する高速撮像方法であって、
    　ラインセンサを備えた複数台の撮像機からなる撮像ユニットと前記ワークを保持する保持テーブルとを所定の移動速度で相対的に水平移動させながら当該ワークを撮像する撮像過程と、
    　前記各撮像機から取得した輝度値に基づいてワークの画像を再構成する画像再構成過程を備え、
    　前記撮像過程は、前記移動速度を撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い速度に調整し、
    　前記撮像機の台数に応じてスキャンレートを均等に分割し、
    　分割後の当該スキャンレートを撮像機に順番に割当て各スキャンレートの始点で撮像機のシャッタリングを行うとともに、各スキャンレート内で撮像機の露光時間を調整したサイクルを繰り返しながら前記ワークを撮像する
    　ことを特徴とする高速撮像方法。     A high-speed imaging method for imaging a workpiece,
    An imaging process for imaging the workpiece while relatively horizontally moving an imaging unit including a plurality of imaging devices provided with line sensors and a holding table for holding the workpiece;
    An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
    In the imaging process, the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the number of imagers.
    Divide the scan rate evenly according to the number of imagers,
    The divided scan rates are sequentially assigned to the imager, and the imager is shuttered at the start point of each scan rate, and the workpiece is imaged while repeating a cycle in which the exposure time of the imager is adjusted within each scan rate. A high-speed imaging method.
  2. 　ワークを撮像する高速撮像方法であって、
    　ラインセンサを備えた複数台の撮像機からなる撮像ユニットと前記ワークを保持する保持テーブルとを所定の移動速度で相対的に水平移動させながら当該ワークを撮像する撮像過程と、
    　前記各撮像機から取得した輝度値に基づいてワークの画像を再構成する画像再構成過程を備え、
    　前記撮像過程は、前記移動速度を撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い速度に調整し、
    　前記撮像機の台数に応じてスキャンレートを均等に分割し、
    　分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機のシャッタリングを行うとともに、分割後のスキャンレートを超えて撮像機の露光時間を終了させ、先行の撮像機と後行の撮像機の露光時間をオーバーラップさせたサイクルを繰り返しながら前記ワークを撮像し、複数画素分にわたって取得された輝度値を撮像機ごとに画素数で平均化した輝度値を記憶部に格納し、
    　前記画像再構成過程は、記憶部から取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する
    　ことを特徴とする高速撮像方法。     A high-speed imaging method for imaging a workpiece,
    An imaging process for imaging the workpiece while relatively horizontally moving an imaging unit including a plurality of imaging devices provided with line sensors and a holding table for holding the workpiece;
    An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
    In the imaging process, the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the number of imagers.
    Divide the scan rate evenly according to the number of imagers,
    The divided scan rate is sequentially assigned to the image pickup device, the shutter of the image pickup device is performed at the start point of each scan rate, the exposure time of the image pickup device is ended beyond the divided scan rate, and the preceding image pickup device The work is imaged while repeating a cycle in which the exposure times of the subsequent imagers are overlapped, and the luminance value obtained by averaging the luminance values acquired over a plurality of pixels by the number of pixels for each imager is stored in the storage unit. Store and
    The image reconstruction process reads out the luminance values in the order obtained from the storage unit, amplifies the luminance value of the pixel at the time of calculation to the luminance value before averaging, and after the current amplification from the luminance value of the pixel calculated immediately before A high-speed imaging method characterized by reconstructing an image of a work based on a luminance value obtained by subtracting the luminance value.
  3. 　ワークを撮像する高速撮像方法であって、
    　同じ複数本のラインセンサを有する複数台の撮像機を備えた撮像ユニットと前記ワークを保持する保持テーブルとを所定の移動速度で相対的に水平移動させながら当該ワークを撮像する撮像過程と、
    　前記各撮像機から取得した輝度値に基づいてワークの画像を再構成する画像再構成過程を備え、
    　前記撮像過程は、前記移動速度を撮像機のラインセンサに応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い速度に調整し、
    　前記撮像機の有するライセンサの本数に応じてスキャンレートを均等に分割し、
    　前記撮像機ごとに分割後のスキャンレートをライセンサに順番に割当て、各スキャンレートの始点でシャッタリングを行うとともに、分割後のスキャンレート内で各ラインセンサへの露光時間を終了させるよう調整したサイクルを繰り返しながら前記ワークを撮像させる過程で、
    　先行の撮像機と後行の撮像機の撮像タイミングをずらしながら交互に同一部位をオーバーラップさせる撮像サイクルを繰り返しながら前記ワークを撮像し、撮像機ごとに複数本のラインセンサにわたって取得された複数画素分の輝度値を積分遅延回路により１画素分の輝度値として記憶部に格納し、
    　前記画像再構成過程は、取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する
    　ことを特徴とする高速撮像方法。     A high-speed imaging method for imaging a workpiece,
    An imaging process of imaging the workpiece while relatively horizontally moving an imaging unit including a plurality of imaging machines having the same plurality of line sensors and a holding table holding the workpiece, at a predetermined movement speed;
    An image reconstruction process for reconstructing an image of a work based on the brightness value acquired from each of the imagers,
    In the imaging process, the moving speed is adjusted to a speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor according to the line sensor of the imager,
    Divide the scan rate evenly according to the number of licensors the imager has,
    A cycle in which the divided scan rates are sequentially assigned to the licensors for each image pickup device, shuttering is performed at the start point of each scan rate, and the exposure time for each line sensor is terminated within the divided scan rate. In the process of imaging the workpiece while repeating
    A plurality of pixels acquired across a plurality of line sensors for each image pickup device by imaging the workpiece while repeating an imaging cycle that alternately overlaps the same part while shifting the image pickup timing of the preceding image pickup device and the subsequent image pickup device. Is stored in the storage unit as a luminance value for one pixel by an integration delay circuit,
    The image reconstruction process reads the luminance values in the order of acquisition, amplifies the luminance value of the pixel at the time of calculation to the luminance value before averaging, and the luminance value after amplification from the luminance value of the pixel calculated immediately before A high-speed imaging method characterized by reconstructing an image of a workpiece based on a luminance value obtained by subtracting.
  4. 　請求項１ないし請求項３のいずれかに記載の高速撮像方法において、
    　複数台の前記撮像機ごとに保持テーブルとの相対的な位置関係を検出する検出過程と、
    　前記検出過程で求めた前記位置関係から撮像機同士の相対的なズレ量を求める演算過程を備え、
    　前記画像再構成過程は、演算過程で求まったズレ量に基づいて、取得画像データの位置を補正しながら画像を再構成する
    　ことを特徴とする高速撮像方法。     The high-speed imaging method according to any one of claims 1 to 3,
    A detection process for detecting a relative positional relationship with the holding table for each of the plurality of imaging devices;
    A calculation process for obtaining a relative deviation amount between imagers from the positional relationship obtained in the detection process,
    The high-speed imaging method characterized in that the image reconstruction process reconstructs an image while correcting the position of acquired image data based on the amount of deviation obtained in the calculation process.
  5. 　ワークを撮像する高速撮像装置であって、
    　前記ワークを保持する保持テーブルと、
    　前記保持テーブルに載置されたワークに向けて光を照射する照明ユニットと、
    　前記ワークを撮像するラインセンサを備えた複数台の撮像機からなる撮像ユニットと、
    　前記保持テーブルと撮像ユニットを所定の移動速度で相対的に水平移動させる水平駆動機構と、
    　前記撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、スキャンレートを撮像機の台数分に均等に分割し、分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機にシャッタリングを行わせるとともに、各スキャンレート内で撮像機の露光時間を調整したサイクルを繰り返しながら複数台の撮像機で前記ワークを撮像させる制御部と、
    　前記各撮像機によって取得された輝度値に基づいてワークの画像を再構成する演算処理部と、
    　を備えたことを特徴とする高速撮像装置。     A high-speed imaging device for imaging a workpiece,
    A holding table for holding the workpiece;
    An illumination unit that irradiates light toward the workpiece placed on the holding table;
    An imaging unit comprising a plurality of imagers equipped with a line sensor for imaging the workpiece;
    A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed;
    Depending on the number of imagers, the moving speed is adjusted to be faster than the optimum moving speed determined from the resolution and scan rate of the line sensor, and the scan rate is equally divided into the number of imagers, and the divided scan rate Are sequentially assigned to the image pickup devices, causing the image pickup device to perform shuttering at the start point of each scan rate, and repeating the cycle in which the exposure time of the image pickup device is adjusted within each scan rate, and the above-described work is performed by a plurality of image pickup devices. A control unit for imaging;
    An arithmetic processing unit that reconstructs an image of a workpiece based on the luminance value acquired by each of the imaging devices;
    A high-speed imaging device comprising:
  6. 　ワークを撮像する高速撮像装置であって、
    　前記ワークを保持する保持テーブルと、
    　前記保持テーブルに載置されたワークに向けて光を照射する照明ユニットと、
    　前記ワークを撮像するラインセンサを備えた複数台の撮像機からなる撮像ユニットと、
    　前記保持テーブルと撮像ユニットを所定の移動速度で相対的に水平移動させる水平駆動機構と、
    　前記撮像機の台数に応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、スキャンレートを撮像機の台数分に均等に分割し、分割後の当該スキャンレートを撮像機に順番に割当て、各スキャンレートの始点で撮像機にシャッタリングを行わせるとともに、分割後のスキャンレートを超えて撮像機の露光時間を終了させ、先行の撮像機と後行の撮像機の露光時間をオーバーラップさせたサイクルを繰り返させながら複数台の撮像機で前記ワークを撮像させ、複数画素分にわたって取得された輝度値を撮像機ごとに画素数で平均化した輝度値を記憶部に格納させる制御部と、
    　前記記憶部から取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する演算処理部と、
    　を備えたことを特徴とする高速撮像装置。     A high-speed imaging device for imaging a workpiece,
    A holding table for holding the workpiece;
    An illumination unit that irradiates light toward the workpiece placed on the holding table;
    An imaging unit comprising a plurality of imagers equipped with a line sensor for imaging the workpiece;
    A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed;
    According to the number of imagers, the moving speed is adjusted to be faster than the optimum moving speed determined from the resolution and scan rate of the line sensor, the scan rate is equally divided into the number of imagers, and the divided scan rate Are sequentially assigned to the image pickup devices, and the image pickup device performs shuttering at the start point of each scan rate, and the exposure time of the image pickup device is terminated beyond the scan rate after the division, and the preceding image pickup device and the subsequent image pickup operation are performed. The image of the workpiece is captured by multiple imagers while repeating a cycle in which the exposure times of the machines overlap, and the brightness value obtained by averaging the brightness values acquired over multiple pixels for each imager is stored A control unit to be stored in the unit,
    Read out the luminance values in the order obtained from the storage unit, amplify the luminance value of the pixel at the time of calculation to the luminance value before averaging, and subtract the luminance value after amplification from the luminance value of the pixel calculated immediately before An arithmetic processing unit for reconstructing an image of the workpiece based on the luminance value;
    A high-speed imaging device comprising:
  7. 　ワークを撮像する高速撮像装置であって、
    　前記ワークを保持する保持テーブルと、
    　前記保持テーブルに載置されたワークに向けて光を照射する照明ユニットと、
    　前記ワークを撮像する同じ複数本のラインセンサを有する複数台の撮像機からなる撮像ユニットと、
    　前記保持テーブルと撮像ユニットを所定の移動速度で相対的に水平移動させる水平駆動機構と、
    　前記撮像機のラインセンサに応じて、ラインセンサの分解能とスキャンレートから決まる最適移動速度よりも速い移動速度に調整し、記撮像機の有するライセンサの本数に応じてスキャンレートを均等に分割し、撮像機ごとに分割後のスキャンレートをライセンサに順番に割当て、各スキャンレートの始点でシャッタリングを行うとともに、分割後のスキャンレート内で各ラインセンサへの露光時間を終了させるよう調整したサイクルを繰り返しながら前記ワークを撮像させる過程で、
    　先行の前記撮像機と後行の前記撮像機の撮像タイミングをずらしながら交互に同一部位をオーバーラップさせる撮像サイクルを繰り返させながら前記ワークを撮像し、撮像機ごとに複数本のラインセンサにわたって取得された複数画素分の輝度値を積分遅延回路により１画素分の輝度値として記憶部に格納させる制御部と、
    　前記記憶部から取得した順に前記輝度値を読み出し、演算時点の画素の輝度値を平均化前の輝度値まで増幅させ、直前に算出した画素の輝度値から現時点の増幅後の輝度値を減算した輝度値に基づいて、ワークの画像を再構成する演算処理部と、
    　を備えたことを特徴とする高速撮像装置。     A high-speed imaging device for imaging a workpiece,
    A holding table for holding the workpiece;
    An illumination unit that irradiates light toward the workpiece placed on the holding table;
    An imaging unit comprising a plurality of imagers having the same plurality of line sensors for imaging the workpiece;
    A horizontal drive mechanism for relatively horizontally moving the holding table and the imaging unit at a predetermined moving speed;
    According to the line sensor of the image pickup device, it is adjusted to a moving speed faster than the optimum moving speed determined from the resolution and scan rate of the line sensor, and the scan rate is equally divided according to the number of licensors of the image pickup device, A cycle in which the scan rate after division for each imaging device is assigned to the licensor in order, shuttering is performed at the start point of each scan rate, and the exposure time for each line sensor is terminated within the scan rate after division. In the process of imaging the workpiece while repeating,
    The workpiece is imaged while repeating the imaging cycle in which the same part is overlapped alternately while shifting the imaging timing of the preceding imaging device and the succeeding imaging device, and acquired over a plurality of line sensors for each imaging device. A control unit that stores a luminance value for a plurality of pixels in a storage unit as a luminance value for one pixel by an integration delay circuit;
    Read out the luminance values in the order obtained from the storage unit, amplify the luminance value of the pixel at the time of calculation to the luminance value before averaging, and subtract the luminance value after amplification from the luminance value of the pixel calculated immediately before An arithmetic processing unit for reconstructing an image of the workpiece based on the luminance value;
    A high-speed imaging device comprising:
  8. 　請求項５ないし請求項７のいずれかに記載の高速撮像装置であって、
    　前記撮像ユニットは、照明ユニットから照射されてワークで反射した光または当該ワークを透過した光を導光する鏡筒部と、
    　前記鏡筒部を導光する光を一部透過させるとともに、角度を変えて一部を反射させて複数台の撮像機に光を導光さる光学部材と
    　を備えたことを特徴とする高速撮像装置。     The high-speed imaging device according to any one of claims 5 to 7,
    The imaging unit includes a lens barrel portion that guides light irradiated from the illumination unit and reflected by the workpiece or light transmitted through the workpiece,
    A high-speed imaging characterized by comprising: an optical member that partially transmits light guided through the lens barrel and reflects a part of the light by changing the angle to guide the light to a plurality of imaging devices. apparatus.
  9. 　請求項５ないし請求項８のいずれかに記載の高速撮像装置であって、
    　複数台の前記撮像機ごとに保持テーブルとの相対的な位置を検出する検出器を備え、
    　前記制御部は、検出器によって検出された位置情報を記憶する記憶部を備え、
    　前記演算処理部は、撮像機ごとに取得された位置情報を前記記憶分から読み出して撮像機同士の相対的なズレ量を求め、当該ズレ量に基づいて取得画像データの位置を補正しながら画像を再構成する
    　ことを特徴とする高速撮像装置。     A high-speed imaging device according to any one of claims 5 to 8,
    A detector that detects a relative position with a holding table for each of the plurality of imaging devices,
    The control unit includes a storage unit that stores position information detected by the detector,
    The arithmetic processing unit reads the position information acquired for each image pickup device from the stored amount, obtains a relative shift amount between the image pickup devices, and corrects the position of the acquired image data based on the shift amount. A high-speed imaging device characterized by reconfiguration.
PCT/JP2014/054103 2013-03-27 2014-02-21 High-speed image capture method and high-speed image capture device WO2014156396A1 (en)

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