JP6522344B2 - Height detection device, coating device and height detection method - Google Patents

Description

  The present invention relates to a height detection apparatus, a coating apparatus, and a height detection method, and more particularly to a technology for detecting the height of an uneven portion formed on the surface of an object.

  Pattern processing technology using a coating needle with a tip diameter of several tens of μm or laser light with a spot diameter of several μm to several tens of μm is a predetermined position even with a fine pattern by combining it with a precision positioning technology of micrometer order. In the prior art, correction operations for flat panel displays, scribing operations for solar cells, etc. have been used (see, for example, Patent Documents 1 to 3). In particular, since processing techniques using a coating needle can be applied to pastes of high viscosity, which dispensers are not good at, they have recently been used to form a 10 μm or more thick film as compared to flat panel displays. For example, it is used for formation of the electronic circuit pattern of semiconductor devices, such as MEMS and a sensor, and printed circuit board wiring. In addition, patterns manufactured by printed electronics technology, which is a promising manufacturing technology in the future, are also classified as thick films, and are processing technologies expected to be used for future applications.

  19 (a) to 19 (c) are diagrams showing defects generated in the manufacturing process of the liquid crystal color filter substrate. 19A to 19C, the liquid crystal color filter substrate includes a transparent substrate, a grid pattern called a black matrix 51 formed on the surface, and a plurality of sets of R (red) pixels 52, G (green B) pixels 53 and B (blue) pixels 54. In the manufacturing process of the liquid crystal color filter substrate, as shown in FIG. 19A, the white defect 55 in which the color of the pixel or the black matrix 51 is lost, or the adjacent pixel and the color as shown in FIG. However, as shown in FIG. 19C, foreign matter defects 57 in which foreign matter adheres to the pixel or the like occur.

  As a method of correcting the white defect 55, the ink having the same color as the pixel in which the white defect 55 exists is attached to the tip of the application needle by the ink application mechanism, and the ink attached to the tip of the application needle is applied to the white defect 55 There is a method of applying and correcting. In addition, as a method of correcting the black defect 56 and the foreign matter defect 57, after the defect portion is laser cut to form a rectangular white defect 55, the ink applied to the tip of the application needle by the ink application mechanism is There is a method of applying to a defect 55 and correcting it (see, for example, Patent Document 1).

  There is also a method of capturing an image of an area including a defect before and after the correction process, comparing the brightness before and after the correction process, and detecting an abnormality in the correction process based on the comparison result (see, for example, Patent Document 2).

JP, 2009-122259, A JP, 2009-237086, A JP, 2012-6077, A

  In a liquid crystal display, a TFT substrate on which an electronic circuit is formed and a liquid crystal color filter substrate expressing the color of a pixel are bonded together, and liquid crystal is sealed between two substrates. Therefore, if projections higher than a predetermined height are present on the surface of at least one of the two substrates, the liquid crystal can not be normally sealed between the two substrates. For this reason, before bonding two substrates together, it is necessary to determine whether bonding is possible by inspecting the presence or absence of a protrusion on the surface of the substrate. For example, when the white defect 55 is corrected by applying a high-viscosity ink, the ink-applied portion made of the applied ink becomes a protrusion on the surface of the liquid crystal color filter substrate. Therefore, after the white defect 55 is corrected, it is necessary to measure the height of the ink application portion. However, according to the method described in Patent Document 2 described above, even if planar defects such as color and density or size and shape of the ink applied portion can be detected, the height of the ink applied portion is detected quantitatively. I could not.

  On the other hand, in order to quantitatively detect the height of the ink-applied portion, a large number of images in the height direction are taken, and the height of each of a plurality of pixels constituting the image is detected based on their luminance. There is a way. In this method, for each of a plurality of pixels constituting an image, a number of arithmetic processing is performed based on many luminances in the height direction to calculate the height, but the load of the arithmetic processing also increases as the number of pixels increases. In order to further increase, in a computer which controls the defect correction apparatus, high processing power is required. In addition, a memory having a large capacity is also required to store the calculation result. As a result, there is a problem that the defect correction apparatus becomes expensive.

  The present invention has been made to solve such problems, and the purpose thereof is the height of the uneven portion formed on the surface of an object, in particular, of an application portion made of a liquid material applied to the surface of a substrate. It is to quantitatively detect the height with an inexpensive device configuration.

  The height detection device according to the present invention detects the height of the uneven portion formed on the surface of the object. The height detection device separates the illumination device for outputting white light and the white light emitted from the illumination device into two luminous fluxes, and irradiates one on the surface of the object and the other on the reference surface, A head unit including an objective lens for obtaining interference light by causing interference light reflected from the both surfaces, an observation optical system for observing interference light, and an imaging device for photographing interference light via the observation optical system, and a head The positioning device for moving the part or the objective lens relative to the object, the positioning device and the imaging device are controlled, and the image is captured while relatively moving the uneven portion and the head portion or the objective lens in the vertical direction And a height detection unit that detects the height of the uneven portion based on the obtained focal position. The height detection unit sets the position of the positioning device at which the brightness of the captured image is maximum as the candidate position of the focus for each of a plurality of pixels constituting the captured image within the imaging cycle of the imaging device And after the imaging device has captured all the images, for each of the plurality of pixels making up the image, a plurality of luminances of the images taken before and after the focal position of the focus determined by the first-stage processing. The focal position is determined on the basis of the contrast value determined on the basis of the above, and a second step of processing is performed to detect the height of the uneven portion on the basis of the focal position.

  The coating apparatus according to the present invention applies a liquid material to the surface of a substrate. The coating apparatus separates the illumination device that outputs white light and the white light emitted from the illumination device into two light fluxes, and irradiates one of the surfaces to the object surface and the other to the reference surface, thereby achieving these two sides. A head unit including an objective lens for causing interference light reflected from the object to obtain interference light, an observation optical system for observing the interference light, and an imaging device for photographing the interference light via the observation optical system; A positioning device that moves the objective lens and the substrate relative to each other, a positioning device, and an imaging device are controlled, and an image is captured while relatively moving the liquid material application unit and the head unit or the objective lens in the vertical direction And a height detection unit that detects the height of the application unit based on the obtained focal position. The height detection unit sets the position of the positioning device at which the brightness of the captured image is maximum as the candidate position of the focus for each of a plurality of pixels constituting the captured image within the imaging cycle of the imaging device And after the imaging device has captured all the images, for each of the plurality of pixels making up the image, a plurality of luminances of the images taken before and after the focal position of the focus determined by the first-stage processing. The focal position is determined on the basis of the contrast value determined on the basis of the above, and a second step of processing is performed to detect the height of the application portion on the basis of the focal position.

  The height detection method according to the present invention is a height detection method for detecting the height of an uneven portion formed on the surface of an object. The height detection method includes: an illumination device that outputs white light; and separating the white light emitted from the illumination device into two light beams, irradiating one of the two beams on the surface of the object and the other on the reference surface, An objective lens for obtaining interference light by causing interference of light reflected from the both surfaces, an observation optical system for observing interference light obtained through the objective lens, and an image pickup apparatus for photographing interference light via the observation optical system A step of relatively moving the head portion including the lens or the objective lens, and the object, and photographing the image while relatively moving the concavo-convex portion and the head portion or the objective lens relative to each other in the vertical direction; Determining the focal position for each of the pixels, and detecting the height of the uneven portion based on the focal position thus determined. In the step of detecting the height of the uneven portion, a position at which the luminance of the captured image is maximized is set as a candidate position of focus for each of a plurality of pixels constituting the captured image within the imaging cycle of the imaging device A step of performing one-step processing, and after the imaging device has captured all images, each of a plurality of pixels constituting the image is photographed before and after the candidate position of the focus determined by the first-step processing Determining a focus position based on a contrast value determined based on a plurality of luminances of the image, and performing a second step of detecting the height of the uneven portion based on the focus position.

  According to the present invention, it is possible to detect the height of the uneven portion formed on the surface of the object, in particular, the height of the application portion made of the liquid material applied to the surface of the substrate. Furthermore, since the height of the application part can be calculated based on the luminance of the pixels constituting the image, quantitative detection can be performed with an inexpensive apparatus configuration without requiring a large-capacity memory for holding the calculation result. Can.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows the whole structure of the defect correction apparatus which is a representative example of the height measuring apparatus by Embodiment 1 of this invention. It is a perspective view which shows the observation optical system and the principal part of an ink application mechanism. FIG. 3 is a view of the main part from the A direction in FIG. 2, showing an ink application operation. It is a figure which shows the surface of the liquid-crystal color filter board | substrate shown in FIG. It is a figure which shows the defect detection operation | movement of the computer for control shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the principal part of the defect correction apparatus by Embodiment 1 of this invention. It is a figure which shows the height detection method of the pixel using the Mirau type interference objective lens shown in FIG. It is a block diagram which shows the control structure for performing a height detection process. It is a figure which shows the test | inspection conditions of the ink application part apply | coated by the ink application | coating mechanism shown in FIG. It is a figure for demonstrating the problem of Embodiment 1. FIG. FIG. 7 is another diagram for describing the problem of the first embodiment. It is a figure for demonstrating the principle of the height detection method by Embodiment 2 of this invention. It is a figure which shows the peak position of one line which exists on an image. It is a figure which shows 0 point of phase (delta) nearest to the peak position shown in FIG. It is a figure which shows the shift | offset | difference amount of the peak position shown in FIG. 12, and 0 point shown in FIG. It is a figure which shows the deviation | shift amount after correction. It is a figure which shows 0 point after correction. It is a figure which shows the test | inspection item of a coating needle. It is a figure which shows the defect of a liquid crystal color filter.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference characters and description thereof will not be repeated.

First Embodiment
[Configuration of defect correction device]
FIG. 1 is a perspective view showing an entire configuration of a defect correction device 1 which is a representative example of a height measurement device according to a first embodiment of the present invention. The defect correction device 1 constitutes a “coating device” that applies a liquid material to the surface of the substrate 7.

  Referring to FIG. 1, the defect correction device 1 includes a correction head unit including an observation optical system 2, a CCD camera 3, a cutting laser device 4, an ink application mechanism 5, and an ink curing light source 6, and the correction A Z stage 8 for moving the head in a direction perpendicular to the liquid crystal color filter substrate 7 to be corrected (Z axis direction), an X stage 9 for mounting the Z stage 8 and moving it in the X axis direction, and the substrate 7 A Y-stage 10 mounted and moved in the Y-axis direction, a control computer 11 for controlling the operation of the entire apparatus, a monitor 12 for displaying an image or the like captured by the CCD camera 3, and a worker for the control computer 11 And an operation panel 13 for inputting a command from the control unit.

  The observation optical system 2 includes a light source for illumination, and observes the surface state of the substrate 7 and the state of the correction ink (liquid material) applied by the ink application mechanism 5. The image observed by the observation optical system 2 is converted into an electrical signal by the CCD camera 3 and displayed on the monitor 12. The laser apparatus 4 for cutting irradiates and removes a laser beam to the unnecessary part on the board | substrate 7 via the observation optical system 2. As shown in FIG.

The ink application mechanism 5 applies a correction ink to the white defect generated on the substrate 7 to correct it. The ink curing light source 6 includes, for example, a CO ₂ laser and irradiates and cures the correction ink applied by the ink applying mechanism 5 with the laser light.

  Note that this apparatus configuration is an example, and for example, the Z stage 8 mounted with the observation optical system 2 and the like is mounted on the X stage, the X stage is mounted on the Y stage, and the Z stage 8 can be phased in the XY directions. The configuration may be called a gantry system, and any configuration may be used as long as the Z stage 8 mounted with the observation optical system 2 etc. can be moved relative to the substrate 7 to be corrected in the X and Y directions.

  Next, an example of an ink application mechanism using a plurality of application needles will be described. FIG. 2 is a perspective view showing the main parts of the observation optical system 2 and the ink application mechanism 5. Referring to FIG. 2, the defect correction device 1 includes a movable plate 15, a plurality of (for example, five) objective lenses 16 of different magnifications, and a plurality of (for example, five) for applying inks of different colors. And an application unit 17.

  The movable plate 15 is provided movably in the X axis direction and the Y axis direction between the lower end of the observation lens barrel 2 a of the observation optical system 2 and the substrate 7. Further, for example, five through holes 15 a are formed in the movable plate 15.

  The objective lens 16 is fixed to the lower surface of the movable plate 15 so as to correspond to the through holes 15 a at predetermined intervals in the Y-axis direction. The five application units 17 are disposed adjacent to the five objective lenses 16 respectively. By moving the movable plate 15, it is possible to arrange the desired application unit 17 above the white defect to be corrected.

  FIGS. 3 (a) to 3 (c) are views showing the main part from the direction A of FIG. 2 and showing the ink application operation. The application unit 17 includes an application needle 18 and an ink tank 19. First, as shown in FIG. 3A, the application needle 18 of the desired application unit 17 is positioned above the white defect to be corrected. At this time, the tip of the application needle 18 is immersed in the correction ink in the ink tank 19.

  Next, as shown in FIG. 3B, the application needle 18 is lowered to project the tip of the application needle 18 from the hole at the bottom of the ink tank 19. At this time, the correction ink adheres to the tip of the application needle 18. Next, as shown in FIG. 3C, the application needle 18 and the ink tank 19 are lowered to bring the tip of the application needle 18 into contact with the white defect, and the correction ink is applied to the white defect. After this, the state returns to the state of FIG.

  A detailed description of the ink application mechanism using a plurality of application needles will be omitted because other various techniques are known. For example, it is shown by patent document 1 (Unexamined-Japanese-Patent No. 2009-122259) etc. The defect correction device 1 can correct a defect using an ink of a desired color among a plurality of inks by using a mechanism as shown in FIG. 2 as the ink application mechanism 5, for example. Defects can be corrected using a coating needle having a desired coating diameter among coating needles.

[Defect correction process]
FIG. 4 is a view showing the surface of the liquid crystal color filter substrate 7. Referring to FIG. 4, liquid crystal color filter substrate 7 includes a plurality of picture elements PC formed on the surface of the glass substrate. A start point DS of the picture element PC and an end DE of the picture element PC are present at the intersection position of the black matrix portions BM formed vertically and horizontally. Also, the beginning DS of the picture element PC is referred to as the position of the color filter. The control computer 11 specifies the position of this color filter. Further, the range from the start DS to the end DE of the picture element PC surrounded by a square in the same figure constitutes the picture element PC.

  In a binary image, a set of pixels having a value 1 in a picture element PC is a color filter section (showing a color filter section CF in the figure) of the picture element, and a set of pixels having a value 0 (hatched portion in the figure) It is a black matrix portion (shown by a black matrix portion BM in the same drawing) of the picture element PC. Each picture element PC has one of the different colors of RGB (Red, Blue, Green), and is repeatedly formed at a constant cycle.

  FIGS. 5A and 5B are diagrams showing an operation when the control computer 11 detects a defect in the horizontal direction of the input image. The control computer 11 detects a defect based on the brightness of the pixel of the color filter. More specifically, the control computer 11 sets the luminance f (x, y) of the position (x, y) in the input image, where P is the interval of picture elements arranged periodically, that is, at equal intervals. On the other hand, a comparison test is performed as shown in the following equation (1).

As described above, the control computer 11 compares the brightness f (x, y) with the brightness f (x−P, y) one cycle earlier and the brightness f (x + P, y) one cycle later. Here, s- _p (x, y) represents the comparison result of f (x, y) and f (x-P, y), and s _{+ p} (x, y) represents f (x, y) The comparison result with f (x + P, y) is shown.

The control computer 11 compares s _H (x, y) with the slice level Td when the signs of s _{− p} (x, y) and s _{+ p} (x, y) match. When the signs of s- _p (x, y) and s _{+ p} (x, y) do not match, the control computer 11 determines the position (x-P, y) or the position (x + P, y). The position (x, y) is excluded from the inspection object because there is a high possibility that it is erroneously detected as a pixel defect in the above, and the inspection reliability is low. Such a configuration can prevent an error in defect detection due to noise of the input image.

Then, when s _H (x, y) is Td or more, the control computer 11 determines that the pixel at the position (x, y) is a defect, and stores the result in d _H (x, y). In d _H (x, y), a pixel with a value of 1 indicates a defect, and a pixel with a value of 0 indicates a normal.

  Next, the control computer 11 calculates the barycentric position of the portion having a value of 1 (that is, the white defect), and the X stage 9 and Y stage so that the calculated coordinates of the barycentric position coincide with the center of the screen of the monitor 12 Control 10 Further, the control computer 11 determines the color of the ink to be applied to the white defect. Further, the control computer 11 calculates the ink application position in the white defect. Such a defect detection process is disclosed, for example, in Japanese Patent Application Laid-Open No. 2007-233299.

  Thereafter, the control computer 11 selects the application unit 17 for applying the ink of the determined color, and makes the determination by bringing the tip of the application needle 18 of the application unit 17 into contact with the calculated ink application position. The corrected ink of the same color is applied to the white defect. The correction ink applied to the white defect is cured by irradiating the light of the light source 6 for ink curing, and the correction of the white defect is completed.

[Height detection process]
In this process, the control computer 11 controls the defect correction apparatus 1 to detect the height of the ink application unit made of the correction ink which has been applied to the white defect and cured.

  In this height detection method, a two-beam interference objective lens is used as the objective lens 16. The two-beam interference objective lens takes advantage of the fact that the interference light intensity at the focal position is maximized, and images the interference light while moving the Z stage 8 relative to the substrate 7 to obtain interference light for each pixel The Z stage position at which the intensity is maximized is determined, and this position is taken as the height of the pixel. This height measurement method is suitable for detection of micro heights of several μm or less.

  The two-beam interference objective lens separates the white light emitted from the light source into two beams and irradiates one surface to the surface of the object and the other to the reference surface, thereby reflecting light from the surface of the object And the reflected light from the reference surface. Although a Mirau-type interference objective lens is used in the present embodiment, a Michelson-type or Linnik-type interference objective lens may be used.

  In addition, a white light source is used as a light source. When a white light source is used, unlike the case where a single wavelength light source such as a laser is used, the interference light intensity is maximized only at the focal position of the two-beam interference objective lens. Therefore, it is suitable for measuring the height.

  FIG. 6 is a layout diagram of optical elements of the observation optical system 2 when the Mirau interference objective lens 30 is used as the objective lens 16. The Mirau-type interference objective 30 comprises a lens 31, a reference mirror 32 and a beam splitter 33.

  At the same time as the objective lens 16 is switched to the Mirau-type interference objective lens 30, the filter switching device 35 inserts the filter 36 into the emission part of the incident light source 34. When light emitted from the epi-illumination light source 34 passes through the filter 36, white light having a central wavelength λ (nm) is obtained.

  For example, a white LED (Light Emitting Diode) may be used as the incident light source 34. The emission spectrum of the white LED has two peaks at wavelengths 450 nm and 560 nm, but the filter 36 is configured by a low pass filter that selectively transmits light centered at 560 nm on the long wavelength side preferable. This is because light having a wavelength of 560 nm is wider than that of light having a wavelength of 450 nm, so that the coherence length can be shortened. The coherence length indicates the distance in the height direction at which interference fringes can be observed. The shorter the coherence length, the smaller the number of data used in the approximate calculation of the contrast value and the gravity center calculation described in the second step to be described later, so that the processing speed can be increased.

  The light passing through the filter 36 is reflected by the half mirror 37 in the direction of the lens 31. The light incident on the lens 31 is split by the beam splitter 33 into light passing in the direction of the substrate 7 and light reflected in the direction of the reference mirror 32. The light reflected by the surface of the substrate 7 and the light reflected by the surface of the reference mirror 32 are merged again by the beam splitter 33 and condensed by the lens 31. Thereafter, the light emitted from the lens 31 passes through the half mirror 37 and then passes through the imaging lens 38 and enters the imaging surface 3 a of the CCD camera 3.

  Usually, the Mirau-type interference objective lens 30 is moved in the direction of the optical axis by the Z stage 8 to cause an optical path length difference between the surface reflected light of the substrate 7 and the surface reflected light of the reference mirror 32. Then, while moving the Mirau-type interference objective lens 30 by the Z stage 8, the interference light generated due to the optical path length difference is imaged by the CCD camera 3. The intensity of the interference light, that is, the brightness becomes maximum when the optical path lengths of the reflected light from the substrate 7 and the reflected light from the reference mirror 32 are equal. At this time, the surface of the substrate 7 is in focus.

  The Z stage 8 constitutes a “positioning device” for relatively moving the correction head unit or the Mirau-type interference objective lens 30 and the substrate 7 to be corrected. The position of the Mirau interference objective lens 30 can be determined by moving the substrate 7 itself up and down with a table in addition to the Z stage 8 or attaching a piezo table to the connecting portion between the Mirau interference objective lens 30 and the observation optical system 2. You may move it up and down.

  Next, the search procedure will be described. The Z stage 8 is moved to the search start position. Assuming that the current position is Zp and the search range is Δ, for example, the Z stage 8 is moved to the initial position (Zp−Δ / 2). Here, the negative direction of the Z stage 8 is made to approach the substrate 7, and the positive direction is made to move away from the substrate 7. The search is performed in the positive direction from the initial position (Zp−Δ / 2), that is, in the direction in which the Z stage 8 moves away from the substrate 7. Therefore, the range of Δ is searched in the positive direction from the initial position (Zp−Δ / 2). The search direction does not necessarily have to be away from the substrate 7 and may be a direction approaching the substrate 7.

  The sampling of the image is started after the Z stage 8 starts moving and reaches a constant speed state. The control computer 11 performs sampling at a constant cycle. Preferably, the image can be sampled more accurately by performing sampling with the period of the vertical synchronization signal of the CCD camera 3.

  The Z stage 8 moves at a predetermined velocity v (μm / sec). The moving velocity v (μm / sec) of the Z stage 8 is determined as follows. Assuming that the central wavelength of white light is λ (μm) and the frequency of the vertical synchronization signal of the CCD camera 3 is F (Hz), the moving speed v (μm / sec) is equal to the sampling period 1 / F (sec) of the image. In the meantime, the Z stage 8 is set to move by λ / 8 (μm). That is, the moving speed v of the Z stage 8 is v = (λ / 8) × F (μm / sec). This moving speed v corresponds to π / 2 in phase increment of white light, and satisfies the Nyquist principle. By changing the phase by π / 2, the peak point of the interference light intensity can be easily detected.

When sampling the image while changing the phase by [pi / 2, the sum of the front and rear ± 2 sheets around the image _{f i} 5 images _{f i-2, f i-} 1, f i, f i + 1, f i + 2 The contrast value M _i is calculated using the following equation (2).

Here, f _i (x, y) indicates the luminance of the pixel at the position (x, y) of the image f _i . Here, i is a number (hereinafter also referred to as “sample number”) attached to the images in the order of acquisition, and i takes values of 1, 2,..., N (N is a natural number).

FIG. 7A shows the relationship between the sample number i and the brightness f _i (x, y). Figure 7 (b) is a diagram showing the relationship between the sample number i and the contrast value M _i. FIG. 7C shows the relationship between the position of the Z stage 8 and the moving speed.

In FIGS. 7A to 7C, the luminance f _i (x, y) and the contrast value M _i both show peaks near the image p. The position of the Z stage 8 corresponding to this peak point is the focal position of the pixel (x, y).

The contrast value M _i represented by the equation (2) indicates an envelope of the luminance f _i shown in FIG. 7A. Therefore, the peak point can be determined by calculating the contrast value M _i . However, since the operation is performed at high speed here, the operation for obtaining the square root and the division are not performed. For example, in the actual calculation, using the following equation (3), calculates a contrast value M _i ♯ obtained by simplifying the contrast value M _i. The contrast value M _i ♯ is proportional to a value obtained by squaring the contrast value M _i, is also shifted, the focus position of the peak point and the pixel of the envelope by using a contrast value M _i ♯ instead contrast value M _i There is nothing to do.

The height detection process consists of a two-step process. In the first stage of processing, for each pixel (x, y) of the image f _i , the position of the Z stage 8 at which the brightness f _i (x, y) is maximum is determined. This utilizes the fact that the luminance f _i (x, y) and the contrast value M _i both exhibit peaks near the pixel p, as can be seen from FIGS. 7 (a) and 7 (b). That is, the peak point of the contrast value M _i can be estimated by finding the image p at which the luminance f _i (x, y) becomes a peak. As a result, the processing range of the second stage can be narrowed, so that the processing speed can be increased. As described above, in the first step processing, the candidate positions of focus are obtained for each of the plurality of pixels constituting the photographed image.

Next, in the second stage of processing, a total (2n + 1) images of ± n sheets (n is a natural number) centered on the image p with the maximum luminance f _i (x, y) are selected, The contrast value M _i # is calculated according to the above equation (3). Then, the position of the Z stage 8 at which the calculated contrast value M _i # is maximum is determined, and the position of the Z stage 8 is taken as the final focal position of the pixel (x, y). That is, the processing of the second stage is to obtain an accurate focal position using the contrast value Mi # based on the candidate position of the focal point obtained by the processing of the first stage.

  FIG. 8 is a block diagram showing a control configuration for executing the height detection step. Referring to FIG. 8, the control configuration relating to the height detection process is configured of CCD camera 3, capture device 40, and processing device 42. The capture device 40 and the processing device 42 are provided in the control computer 11.

  The capture device 40 samples an image at a fixed cycle (preferably, the cycle of the vertical synchronization signal of the CCD camera 3). Specifically, the capture device 40 uses the vertical synchronization signal of the CCD camera 3 as a trigger to start sampling of an image. Then, when the sampling of the image is completed, the sampled image is immediately transferred to the processing device 42. At this time, the capture device 40 directly transfers the image to the storage unit 44 of the processing device 42. For example, DMA (Direct Memory Access) transfer is used for this image transfer. The sampling and transfer of the image by the capture device 40 are repeatedly performed in the sampling period 1 / F (seconds) of the image, where the frequency of the vertical synchronization signal of the CCD camera 3 is F (Hz).

The processing device 42 includes a storage unit 44 and a central processing unit 46. The image f _i is transferred from the capture device 40 to the storage unit 44 at a sampling period 1 / F (seconds) of the image. The storage unit 44 stores the transferred images f _i in order. Immediately after the image is transferred to the storage unit 44, the central processing unit 46 starts the process of obtaining the maximum value of the luminance f _i (x, y), which is the first-stage process. Then, the central processing unit 46 completes the process of obtaining the maximum value of the brightness f _i (x, y) by the time immediately before the next image transfer. That is, the first stage processing is performed during the sampling period 1 / F (seconds) of the image.

(Process of the first stage)
Hereinafter, the procedure of the process of obtaining the maximum value of the brightness f _i (x, y), which is the process of the first stage, will be described in detail.

In FIG. 8, three storage areas in which storage cells are two-dimensionally arranged are prepared in the storage unit 44 so as to have the same resolution as the resolution of the CCD camera 3. Among the three storage areas, the first storage area stores the maximum value of the luminance f _i (x, y) at the position (x, y) of the image f _i . That is, the maximum value of the luminance of the corresponding pixel (x, y) is stored in each of the two-dimensionally arranged storage cells. In the following description, the maximum value of the luminance f _i (x, y) is denoted as “Max (x, y)”.

The second storage area stores the position of the Z stage 8 when the image f _i with the maximum brightness f _i (x, y) is captured. That is, the position of Z stage 8 at which the luminance of the corresponding pixel (x, y) becomes maximum is stored in each of the two-dimensionally arranged storage cells. In the following description, the position of the Z stage 8 when the luminance f _i (x, y) is maximum is denoted as “Pz (x, y)”.

The third storage area stores a sample number i when the image f _{i for} which the brightness f _i (x, y) is maximum is captured. That is, the sample number i of the image f _i at which the luminance of the corresponding pixel (x, y) is maximum is stored in each of the two-dimensionally arranged storage cells. In the following description, the sample number i of the image f _i for which the luminance f _i (x, y) is maximum is denoted as “I (x, y)”.

The three values of Max (x, y), Pz (x, y), and I (x, y) stored in storage unit 44 are set to “0” in the initial state before the start of the search. ing. When the search is started, the image is sequentially transferred from the capture device 40 to the storage unit 44 at a sampling period of 1 / F (seconds). When the transfer of the image f _i is completed, the central processing unit 46 compares the brightness f _i (x, y) with Max (x, y) for each pixel, and based on the comparison result, Max (x, y) , Pz (x, y), I (x, y) values are updated. Specifically, the central processing unit 46 calculates the luminance f _i (x, y) at the position (x, y) of the image f _i and the maximum value Max (x, y) of the luminance of the pixel (x, y) Compare with. When the relationship of f _i (x, y) ≦ Max (x, y) holds, the central processing unit 46 maintains the value of Max (x, y). At this time, the central processing unit 46 also maintains the values of Pz (x, y) and I (x, y).

On the other hand, when the relationship of f _i (x, y)> Max (x, y) holds, the central processing unit 46 rewrites the value of Max (x, y) to the brightness f _i (x, y). . Moreover the central processing unit 46, Pz (x, y) pixel values _f i (x, y) the value of rewrites to the position of the Z stage 8 corresponding to, I (x, y) the luminance values of _f i ( Rewrite to the sample number i of x, y).

The central processing unit 46 performs the comparison operation of the luminance f _i (x, y) and Max (x, y) described above and the rewriting operation of the storage unit 44 according to the comparison result from the capture device 40 to the storage unit 44. This is performed using a period from when the image is transferred to when the capturing device 40 starts sampling the next image. For example, assuming that the resolution of the CCD camera 3 is 640 × 480 and the luminance f _i (x, y) is 1 byte, the size of the image data transferred from the capture device 40 to the storage unit 44 is 307,200 bytes Become. On the other hand, when the frequency of the vertical synchronization signal of the CCD camera 3 is 120 Hz, the sampling period of the image is 1/120 sec. Therefore, the capture device 40 captures 307, 200-byte image data every 1/120 seconds (about 8.3 ms) and transfers the image data to the storage unit 44 of the processing device 42. Data transfer from the capture device 40 to the storage unit 44 can be performed in about 2 ms by using DMA transfer. Therefore, the processing unit 42 uses the time of about 6.3 ms excluding the data transfer time of about 2 ms, out of the sampling period of about 8.3 ms, for the luminance f _i (x, y). Execute processing to find the maximum value.

In this manner, the first stage processing is performed using the idle time after data transfer for each image sampling cycle. Thereby, when sampling of all the images within the search range is completed, the storage unit 44 stores the maximum value (= Max (x, y)) of the luminance f _i (x, y) and the luminance f for each pixel. The position of Z stage 8 when _i (x, y) is maximum (= Pz (x, y), and the sample number of image f _i where luminance f _i (x, y) is maximum (= I (x) , Y)) is stored.

(Process of the second stage)
Next, the procedure of the process of obtaining the position of Z stage 8 at which the contrast value M _i # is maximum, which is the second-step process, will be described in detail. The processing of the second stage is performed by the central processing unit 46 after sampling of all the images within the search range is completed.

The central processing unit 46 reads, from the storage unit 44, the sample number i (= I (x, y)) at which the brightness f _i (x, y) is maximum for each pixel. The central processing unit 46 uses a total of (2n + 1) images of ± n sheets before and after the image f _i of the sample number i indicated by I (x, y) to obtain the contrast value M _i ♯ (x , Y) find the peak point.

Specifically, assuming that the sample number of each of the (2n + 1) images is j, the sample number j is I (x, y) -n, I (x, y) -n + 1,. x, y) -1, I (x, y), I (x, y) +1,..., I (x, y) + n-1, I (x, y) + n. The central processing unit 46 calculates a total of (2n + 1) contrast values M _j # (x, y) by substituting the luminance f _j (x, y) of the image f _j into the equation (3).

Here, assuming that the position of the Z stage 8 corresponding to the contrast value M _j # (x, y) is Z _j , Z _j can be expressed by the following equation (4).

As described in FIG. 7B, since the contrast value M _j # shows a mountain-like tendency that is symmetrical about the peak point, a curve showing the contrast value M _j # using a quadratic function or a Gaussian function Can be approximated. Therefore, central processing unit 46 approximates the relationship between contrast value M _j # and position Z _j of Z stage 8 by a quadratic function or a Gaussian function, and Z stage in which contrast value M _j # is a peak from the obtained function. The position Z _j of 8 is obtained. Then, the position Z _j of the Z stage 8 is set to the height of the pixel (x, y).

  As described above, in the height detection step, the Z stage position at which the luminance of the captured image is maximized is set as the first stage processing for each of the plurality of pixels constituting the captured image. Let it be a candidate position. Thereafter, as the second stage processing, the contrast value is determined from the brightness of the image photographed in the vicinity of the focus candidate position, and the Z stage position at which the contrast value of each pixel is maximum is determined as the focus position. The height of the ink application unit is detected.

  With such a configuration, the process of calculating the contrast value for each pixel can be omitted in the first-stage process, so the calculation load on the control computer 11 can be reduced. In addition, since it is not necessary to store the contrast value of each pixel, a large capacity memory is not necessary. As a result, the control computer can be configured inexpensively.

  In addition, since the process of the first step can be performed using the idle time after transferring the image within the imaging cycle (sampling cycle of the image in the CCD camera 3) of the imaging device, all the processes within the search range It is possible to reduce the numerical operation processing after the completion of the imaging of the image. As a result, it is possible to shorten the working time of the height detection process.

In the second-step processing described above, the configuration in which the contrast value M _i # is approximated by a quadratic function or a Gaussian function has been described, but the barycentric positions of (2n + 1) contrast values M _i # are determined and determined The position of the center of gravity may be taken as the peak position. This barycentric position indicates the center position of the left-right symmetric data as shown in FIG. 7 (b). Placing the center of gravity position and _{Z g, Z g} may be calculated using the following equation (5).

[Height inspection process]
In this step, the ink-applied portion is extracted based on the images before and after application, and the heights of the extracted ink-applied portion and the reference portion are compared. For example, as described in Patent Document 2 (Japanese Patent Laid-Open No. 2009-237086), the brightness of the image before and after application is compared, and the ink application part is extracted based on the comparison result. Let the extraction result of the ink application unit be b (x, y). b (x, y) is a function that returns 1 if the pixel at position (x, y) is an ink-coated area, and 0 otherwise.

  The reference portion is a normal portion of the substrate 7 to which the correction ink is not applied, and is extracted from the image before or after the application. The central coordinates (Δx, Δy) of the reference portion with respect to the application start point, and the vertical and horizontal sizes (w, h) are determined in advance. Here, let h (x, y) be the image in which the height information obtained in the height detection step is stored, and let the coordinates of the application start point be (xs, ys), and the height of the reference part be (xs + Δx, The average value of heights within a range of (± w / 2, ± h / 2) centering on ys + Δy) is used. The reference part is not limited to the above method, and for example, a characteristic part of the substrate 7 may be detected by pattern matching or the like and set inside, or may be set in an area offset from the detection position obtained by pattern matching .

  The height average value of the reference part obtained as described above is h0. Subtract h0 from the height image h (x, y), and let the subtraction result be h '(x, y). Subsequently, the total value, the maximum value, the minimum value, the variance value, and the average value of h '(x, y) of the pixel showing the value 1 of the ink application site b (x, y) extracted earlier are calculated. Note that the vertical and horizontal dimensions of one pixel are (mx, my). The unit is nm.

  The total value corresponds to the volume of the ink application unit, and is effective for checking whether a predetermined ink application amount can be ensured or the upper limit is not exceeded. The total value is calculated using the following equation (6).

  The maximum value is the maximum value of h '(x, y) of the pixel where the value of b (x, y) is 1, and it is effective for checking whether the height of the ink application part exceeds the upper limit. It is.

  The minimum value is the minimum value of h ′ (x, y) of the pixel where the value of b (x, y) is 1, and is effective for checking whether a certain thickness can be secured.

  The dispersion value is effective when it is desired to evaluate the uniformity of the height of the ink applied portion. The variance is calculated according to the following equation (7).

  The average value is effective for checking whether or not a certain height or more can be secured over the entire ink application unit. The average value is calculated according to the following equation (8).

  The control computer 11 determines whether the ink application unit is normal based on at least one of the calculated total value, maximum value, minimum value, variance value, and average value.

  The defect correction device 1 according to the first embodiment has a function of registering inspection items in the order of application in advance, and it becomes possible to change inspection items and tolerances depending on the types of coating needle, substrate 7 and correction ink. There is.

  FIG. 9 is a diagram showing inspection conditions when ink is applied by the ink applying mechanism 5 shown in FIG. The ink application mechanism 5 has five application needles, and inspection conditions can be registered for each application needle. When the application is performed with the corresponding application needle, the registered content is referred to. The AND is passed when all the specified conditions are satisfied, and the OR is passed when any one of the conditions is satisfied.

  It is applied when numerical values are designated in the columns of “total value”, “maximum value”, “minimum value”, “dispersion value”, and “average value”, and the respective determinations are summarized by “final determination”. In this example, two types of settings of “AND” or “OR” are possible for “final determination”. The numerical value column is specified by a pair of (lower limit value, upper limit value). When both the lower limit value and the upper limit value are designated numerically, the condition is satisfied when the value of the corresponding inspection item is equal to or more than the lower limit value and less than the upper limit value. When the lower limit value is "-", the condition is satisfied when the value is less than the upper limit value. When the upper limit value is "-", the condition is satisfied when the value is equal to or more than the lower limit value. It does not judge when both are blank.

  As described above, according to the height detection device according to the first embodiment of the present invention, an image is captured while the ink application unit and the objective lens are relatively moved in the vertical direction, and each of the plurality of pixels constituting the captured image The height of the ink application unit can be detected based on the determined focal position by determining the focal position for. As a result, accurate inspection such as change in the viscosity of the correction ink and detection of an abnormal state of the ink application mechanism can be performed, which can contribute to improvement in the yield of the manufacturing process.

  Further, in the step of detecting the height of the ink application unit, the position of the Z stage (positioning device) at which the luminance of the photographed image becomes maximum is set as the candidate position of focus for each of a plurality of pixels constituting the photographed image. Processing (first-stage processing), and for each of a plurality of pixels constituting the image, the focal position is determined based on the contrast values obtained based on the plurality of luminances of the image photographed before and after the focal position. It is executed by the process to be determined (the second stage process). In this step, the processing of the first stage is performed using the idle time (vacant time after image transfer) within the imaging cycle of the imaging device, and the processing of the second stage after the imaging of all the images is completed. Do.

  According to this, since it is not necessary to store the contrast value of each pixel for each captured image in the first stage processing, it is not necessary to prepare a large capacity memory. Therefore, the control computer can be configured inexpensively.

  In addition, since the process of the first stage can be completed and the process of the first stage can be completed using the idle time in the imaging cycle, the numerical operation process after the imaging of the image can be reduced. As a result, it is possible to shorten the working time of the height detection process.

  Furthermore, in the first step processing, when trying to calculate the contrast value of each pixel by using the vacant time within the imaging cycle, the control computer is required to have a high arithmetic processing capability, resulting in an increase in the device cost. I will. On the other hand, in the first embodiment, instead of calculating the contrast value of each pixel, it is not necessary to speed up the control computer since the candidate position of the focus of each pixel is determined using luminance. .

Second Embodiment
The second embodiment relates to a method of enhancing the detection accuracy of the height detection method of the first embodiment. First, problems of the first embodiment will be described.

  Assuming that the wavelength of the light source is λ, the intensity gλ of the interference light waveform can be expressed by the following equation (9).

  Here, s is a sampling position, h is a height of the ink application portion, and α and γ are coefficients determined from the amplitude of the white light.

  FIG. 10 is a diagram showing the relationship between the sampling position s and the interference light intensity gλ. The interference light intensity in FIG. 10 is calculated using the above equation (9). ● indicates a sampling point. The sampling point interval is λ / 8 (nm) as in FIG.

  The interference light intensity is maximum when s = h in the above equation (9), that is, when the optical path length of the reflected light from the substrate 7 and the optical path length of the reference light from the reference mirror 32 are the same, and coincides with the peak of the envelope. Do. If an envelope is superimposed on FIG. 10, it will become like FIG. In the actual measurement, α and γ in the above equation (9) are not constant due to the influence of noise, and gλ fluctuates, which causes a shift in the position of the peak point of the envelope.

(Merit of using phase)
The phase information can be obtained without the influence of α and γ in the above equation (9). Here, in order to make the explanation easy to understand, light of center wavelength λ is considered. Assuming that the phase 2π (2s-2h) / λ of the interference light waveform is δ, the above equation (9) is gλ = α (1 + γ cos δ). Here, following Formula (10) is obtained from Euler's formula.

  Here, when the above equation (10) is subjected to Fourier transform, and only the spectrum of the second term on the right side is extracted by a band pass filter and inverse Fourier transformed, the following equation (11) is obtained.

  If the above equation (11) is expressed as a trigonometric function by Euler's formula, the following equation (12) is obtained.

  Here, it can be seen that the phase δ is expressed by the following equation (13) and can be calculated without being influenced by α and γ.

  As a method of calculating the phase, in addition to the above equation (13), there is also a method using the following equation (14) called a five-step method.

  Besides this, there are four-step method and seven-step method. Here, as long as the phase of the interference light can be calculated, the invention is not particularly limited to Formula (13) or Formula (14).

[Combined use of peak point and phase]
The peak of the envelope may be misaligned due to noise, but the phase δ can theoretically minimize the effect of noise, and it is more accurate than the peak of the envelope Detection is possible. Therefore, in the present embodiment, the height of the ink application portion is detected using both the peak of the envelope and the phase δ.

(Occurrence of phase jump)
The interference light intensity gλ in the above equation (9) is maximum when s = h, and the envelope has a peak. At the same time, the phase δ becomes δ = 2 (2s-2h) = 2π (2h-2h) / λ = 0. However, since the period of the phase is 2π, the position where the phase δ is 0 (also referred to as 0 point) similarly appears every 2π, so the 0 point of the nearest phase σ is adopted as the peak of the envelope. To In the present invention, the peak of the envelope is called a first-order height, and the zero point of the phase σ is called a second-order height.

  FIG. 12 shows the envelope superimposed on the phase, and the sawtooth waveform shows the phase. As can be seen from FIG. 13, there are 0 points of the phase δ one on each side of the peak. In order to obtain the second-order height, the nearest zero point is adopted as the peak point, but when the peak position is shifted due to noise, a selection error of the zero point is caused. When this selection error occurs, a phase jump of 2π occurs between adjacent pixels because the phase δ takes a value of −π to π.

  FIG. 13 is a diagram showing the peak position of one line on the image. FIG. 13 shows data of one line in the horizontal direction when the inclined plane is measured. The horizontal axis in FIG. 13 indicates the pixel position, and the vertical axis indicates the sample number of the image. The higher the sample number, the higher. When the sample number changes by 1, the height changes by λ / 8.

  Further, FIG. 14 shows the 0 point of the phase δ closest to the peak position shown in FIG. A phase jump occurs at D and E in FIG. Moreover, when FIG. 13 and FIG. 14 are compared, it is also understood that the variation of 0 point of the phase δ is smaller.

(Detection and correction of phase jump)
Since the factor causing the phase jump is a misselection of 0 point of the phase δ which is on the left and right of the peak point of the envelope, finally, either left or right is selected unifyingly in any pixel It should be corrected to

  Therefore, as post-processing, the amount of deviation between the peak point of the envelope and the zero point of the phase δ is determined, and correction processing is performed such that the sign of the amount of deviation coincides for almost all pixels on the image. Fix it. In addition, although the height of a pixel changes with this process, in this inspection method, since relative height is used for evaluation of height, there is no problem.

  First, let Δ be the amount of deviation between the peak point and the 0 point of the phase δ, let T be the threshold, let t be the amount of correction of the threshold, and let M be the number of corrections. Assuming that the peak of the envelope of the position (x, y) on the image is J (x, y) and the zero point of the phase is K (x, y), the deviation amount Δ (x, y) is Δ (x , Y) = K (x, y) -J (x, y).

  Here, Δ (x, y) at the same place as FIG. 13 is shown in FIG. The horizontal axis in FIG. 15 indicates the pixel position, the vertical axis indicates Δ (x, y), and a change of 1 corresponds to λ / 8. Next, Δ (x, y) is compared with the threshold T. If Δ (x, y) <T, then K (x, y) is K ′ (x, y) = K (x, y). y) + 4 If Δ (x, y)> T, then K ′ (x, y) = K (x, y). Note that “4” in K ′ (x, y) = K (x, y) +4 indicates the correction amount of phase jump, and the value is equal to the number of samples when the phase changes by 2π. Note that it is explained in paragraph 0050 that the sampling interval is π / 2 in terms of the amount of change in phase.

  Thereafter, the corrected K ′ (x, y) of all the pixels (x, y) is compared with at least one pixel adjacent to (x, y) to obtain the sum S of difference values. Note that the difference value is an absolute value of the difference from K '(x, y) of the adjacent pixel. For example, the difference value with (x + 1, y) is | K ′ (x, y) −K ′ (x + 1, y) |. Further, the calculated sum value S is associated with the threshold value T and held. Next, the correction amount t is added to the threshold T to obtain a new threshold T. Again, K ′ (x, y) is determined for all the pixels (x, y) on the image, and the sum value S is determined.

  The above processing is repeated M times, and finally, the minimum value of the obtained total value S is obtained, and K ′ (x, y) is obtained again using the threshold value T when the minimum value is indicated. Let '(x, y) be the third-order height of each pixel.

  The final K '(x, y) of FIG. 14 is shown in FIG. Further, Δ (x, y) at this time is shown in FIG. In FIG. 15, the threshold value T starts from -4, and a total of 80 corrections are performed with the correction amount t being 0.1. The threshold T changes to four. It can be seen from FIG. 17 that the phase jump is corrected.

(Switching of detection method)
The amount of ink applied per time depends on the viscosity of the ink. A high viscosity ink has a large surface tension, so it becomes a thick film as compared to a low viscosity ink. The nature of the ink is often clarified in advance by a sample test performed in advance.

  The criteria for determining the amount of applied ink differ depending on the pattern to be applied, and is less than submicron in the case of thin films such as flat panel displays and semiconductors, but in the case of film thickness such as printed circuit board electrodes It is.

  Since the required detection accuracy also differs depending on the ink to be applied and the pattern of the application target, in the present detection method, the height information to be used can be switched depending on the ink to be applied.

  The ink to be applied can be changed for each application needle, for example, when the ink application mechanism 5 shown in FIG. 2 is used. Therefore, the “needle-inspection item correspondence table” shown in FIG. 18 is provided with a selection column of “height type”, and the height type to be used when applied with the corresponding needle is registered. For example, when applying with the application needle A, the third height is used, and when applying with the application needle B, the first height is used.

  Further, since the film thickness is different for each ink, the scan range can be set for each application needle. As a result, the tact time suitable for the ink can be set, and the inspection time can be made more efficient.

  In the second embodiment, the height of the ink application portion can be detected with higher accuracy than the first embodiment.

  In the first and second embodiments described above, the present invention is applied to the measurement of the height of the ink application portion made of the correction ink applied to the liquid crystal color filter substrate 7, but the present invention is limited thereto. However, the present invention can be applied to the measurement of the height of the uneven portion formed on the surface of the object. For example, the present invention can be applied to the measurement of the height of a paste application portion made of a conductive paste applied to a disconnection defect portion of a wiring on the surface of a TFT substrate. Alternatively, the present invention can be applied to the measurement of the surface roughness of a glass substrate for a flat panel display such as a liquid crystal display device or an organic EL display device. Furthermore, it is applicable also to the measurement of the depth of the fine groove | channel formed on the board | substrate by laser irradiation.

  Furthermore, in the above-described first and second embodiments, the height of the application part can be calculated based on the luminance of the pixels forming the image, and a large-capacity memory for holding the calculation result is required. Because it does not, it is suitable for the shape measurement of a thick film which requires more images thicker than the pattern exemplified in the previous paragraph. The thick film generally refers to a film having a thickness of 10 μm or more, and is used, for example, for an electronic circuit pattern of a semiconductor device such as a MEMS or a sensor or a printed board wiring. These are five to ten times the film thickness of the pattern illustrated in the previous paragraph. In addition, patterns produced by printed electronics technology, which is a promising manufacturing technology in the future, are also classified as thick films.

  It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is not limited to the description of the embodiment described above, but is intended to be indicated by the claims and include all modifications within the scope.

  DESCRIPTION OF SYMBOLS 1 defect correction apparatus, 2 observation optical system, 2a observation lens barrel, 3 CCD camera, 4 cutting laser device, 5 ink coating mechanism, 6 ink curing light source, 7 liquid crystal color filter substrate, 8 Z stage, 9 X stage, DESCRIPTION OF SYMBOLS 10 Y stage, 11 control computer, 12 monitor, 13 operation panel, 15 movable plate, 16 objective lens, 17 application unit, 18 application needle, 19 ink tank, 30 Milau type interference objective lens, 31 lens, 32 reference mirror, 33 beam splitter, 34 incident light source, 35 filter switching device, 36 filter, 37 half mirror, 38 imaging lens, 40 capture device, 42 processing device, 44 storage unit, 46 central processing unit, 51 black matrix, 52 R pixel , 53 G pixels, 54 B pixels, 55 white defects, 56 black defects, 57 Foreign object defect.

Claims (7)

A height detection device for detecting the height of an uneven portion formed on the surface of an object, comprising:
An illumination device for outputting white light, and white light emitted from the illumination device is divided into two light beams, one is irradiated on the surface of the object and the other is irradiated on the reference surface, and the reflected light from both surfaces is A head unit including an objective lens for obtaining interference light by interference, an observation optical system for observing the interference light, and an imaging device for photographing the interference light via the observation optical system;
A positioning device for relatively moving the head unit or the objective lens and the object;
An image is captured while relatively moving the uneven portion and the head unit or the objective lens in the vertical direction by controlling the positioning device and the imaging device, and a focal position of each of a plurality of pixels constituting the captured image And a height detection unit that detects the height of the uneven portion based on the determined focal position.
The height detection unit
A first-stage process in which the position of the positioning device at which the luminance of the captured image becomes maximum is set as a candidate position of focus for each of a plurality of pixels constituting the captured image within the imaging cycle of the imaging device When,
After the image pickup apparatus picks up all the images, for each of a plurality of pixels constituting the image, a plurality of luminances of the images taken before and after the candidate position of the focus determined by the first step processing A focal position is determined based on the contrast value determined on the basis, and a second step of processing is performed to detect the height of the uneven portion based on the focal position .
The height detection unit sets a position of the positioning device at which the contrast value reaches a peak in the second step processing as a focal position of the pixel.
The height detection unit may be configured to perform the second stage processing.
The position of the positioning device at which the contrast value peaks is taken as the primary height
Furthermore, the phase is determined based on the luminance of the image in the vicinity of the candidate position of the focus determined by the first step processing, and the primary height among the positions of the plurality of positioning devices having a phase of 0 Position of the positioner where the nearest phase is 0 to
Furthermore, the first height and the second height are compared with each other to detect occurrence of phase jump, and when the phase jump is detected, the second height is corrected, and the third height with the phase jump corrected. detecting the height detector. The height detection unit
When calculating the third-order height, a threshold is provided, and for each of a plurality of pixels constituting an image, a value obtained by subtracting the first-order height from the second-order height is compared with the threshold And the position of the positioning device whose phase is increased by 2π with respect to the current second-order height when the subtraction result is below the threshold is taken as the second-order height after correction; For the next height, for each pixel, the difference value between the adjacent pixels is calculated to obtain the sum of the difference values of the plurality of pixels,
The process of obtaining the sum of the difference values of the plurality of pixels is repeatedly performed while correcting the threshold value M times in total by a predetermined correction amount while holding the sum of the difference value for each threshold value And
2. The height detection according to claim 1 , wherein the second-order height corrected with the threshold value that minimizes the total sum of the difference values among the second-order heights after the correction is the third-order height detection. apparatus. The lighting device is a white LED,
The optical device further comprises a filter provided between the illumination device and the objective lens, for selectively transmitting white light on the long wavelength side of two peaks of the emission spectrum of the white LED. Or the height detection apparatus as described in 2 . An application apparatus for applying a liquid material to the surface of a substrate, wherein
An illumination device for outputting white light, and white light emitted from the illumination device is divided into two light beams, one is irradiated on the surface of the object and the other is irradiated on the reference surface, and the reflected light from both surfaces is A head unit including an objective lens for obtaining interference light by interference, an observation optical system for observing the interference light, and an imaging device for photographing the interference light via the observation optical system;
A positioning device for relatively moving the head unit or the objective lens and the substrate;
The positioning device and the imaging device are controlled, an image is captured while relatively moving the liquid material application unit and the head unit or the objective lens relative to each other, and each of a plurality of pixels constituting the captured image And a height detection unit that detects the height of the application unit based on the determined focus position.
The height detection unit
A first-stage process in which the position of the positioning device at which the luminance of the captured image becomes maximum is set as a candidate position of focus for each of a plurality of pixels constituting the captured image within the imaging cycle of the imaging device When,
After the image pickup apparatus picks up all the images, for each of a plurality of pixels constituting the image, a plurality of luminances of the images taken before and after the candidate position of the focus determined by the first step processing A focal position is determined based on the contrast value determined on the basis, and a second step of processing is performed to detect the application unit based on the focal position .
The height detection unit sets a position of the positioning device at which the contrast value reaches a peak in the second step processing as a focal position of the pixel.
The height detection unit may be configured to perform the second stage processing.
The position of the positioning device at which the contrast value peaks is taken as the primary height
Furthermore, the phase is determined based on the luminance of the image in the vicinity of the candidate position of the focus determined by the first step processing, and the primary height among the positions of the plurality of positioning devices having a phase of 0 Position of the nearest positioner to the second height,
Furthermore, the first height and the second height are compared with each other to detect occurrence of phase jump, and when the phase jump is detected, the second height is corrected, and the third height with the phase jump corrected. To detect the coating device. The height detection unit
When calculating the third-order height, a threshold is provided, and for each of a plurality of pixels constituting an image, a value obtained by subtracting the first-order height from the second-order height is compared with the threshold And the position of the positioning device whose phase is increased by 2π with respect to the current second-order height when the subtraction result is below the threshold is taken as the second-order height after correction; For the next height, for each pixel, the difference value between the adjacent pixels is calculated to obtain the sum of the difference values of the plurality of pixels,
The process of obtaining the sum of the difference values of the plurality of pixels is repeatedly performed while correcting the threshold value M times in total by a predetermined correction amount while holding the sum of the difference value for each threshold value And
The coating apparatus according to claim 4 , wherein the second-order height corrected with the threshold value that minimizes the sum of the difference values among the second-order heights after the correction is the third-order height. The lighting device is a white LED,
The light emitting device according to claim 4 , further comprising: a filter provided between the illumination device and the objective lens, for selectively transmitting white light on the long wavelength side of two peaks of the emission spectrum of the white LED. Or the coating apparatus as described in 5 . A height detection method for detecting the height of an uneven portion formed on the surface of an object, comprising:
An illumination device for outputting white light, and white light emitted from the illumination device is divided into two light beams, one is irradiated on the surface of the object and the other is irradiated on the reference surface, and the reflected light from both surfaces is An objective lens for obtaining interference light by causing interference, a head unit including an observation optical system for observing the interference light, and an imaging device for photographing the interference light via the observation optical system, or the objective lens Moving the object relative to the object;
An image is captured while relatively moving the uneven portion and the head unit or the objective lens in the vertical direction, and a focal position is determined for each of a plurality of pixels constituting the captured image, and the focal position is determined based on the determined focal position. Detecting the height of the uneven portion,
The step of detecting the height of the uneven portion is:
In the shooting period of the imaging device, for each of a plurality of pixels constituting an image the photographing, the brightness of the image the photographing shall be the candidate position of the focal point on the basis of the photographing position location of the image is maximized Performing one step of processing;
After the image pickup apparatus picks up all the images, for each of a plurality of pixels constituting the image, a plurality of luminances of the images taken before and after the candidate position of the focus determined by the first step processing obtains the focus position on the basis of the contrast value determined on the basis of viewing including the step of performing processing of the second step of detecting a height of the uneven portion on the basis of the focus position,
In the step of performing the second stage processing, the imaging position at which the contrast value reaches a peak is set as the focal position of the pixel,
In the step of performing the second stage processing, the imaging position at which the contrast value reaches a peak is set to a primary height,
Furthermore, a phase is determined based on the luminance of the image in the vicinity of the candidate position of the focus determined by the first step processing, and a plurality of imaging positions where the phase is 0 are closest to the primary height. Let the shooting position where the phase is 0 be the secondary height,
Furthermore, the first height and the second height are compared with each other to detect occurrence of phase jump, and when the phase jump is detected, the second height is corrected, and the third height with the phase jump corrected. detecting the height detection method.

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