JP2005069796A - Substrate inspection device and substrate observation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate inspection device and a substrate observation device for performing quality determination of a very small concentration fluctuation by improving an S/N ratio by emphasizing a micro-concentration fluctuation generated in a colored film applied onto a substrate by an optical filter. <P>SOLUTION: This device has a camera 22 having an imaging element, a stage for grasping the substrate, an illumination means 24 for illuminating the substrate from behind the stage, a control means for controlling a camera shutter, the optical filter 21 for transmitting only a wavelength zone having a low light transmittance of the substrate on the front of an imaging lens of the camera and/or the illumination means, a recording means for accumulating and preserving an image acquired from the camera, and a determination means for performing quality determination based on the image. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention inspects for defects due to minute density fluctuations of a colored film that is applied uniformly over the entire surface of a planar substrate or applied in a multi-faceted state over the entire surface and is expected to have an originally uniform density with high sensitivity. The present invention relates to a substrate inspection apparatus and a substrate observation apparatus.

A substrate inspection apparatus for inspecting a density variation of a colored film applied to a planar substrate and a substrate observation apparatus for observing the density variation are obtained by collecting images by using a two-dimensional CCD camera and obtaining an image. A masking process is performed on a portion where no colored film is present, and determination processing or image display is performed.
JP-A-10-185663

  In the colored film applied on the substrate, a region having a changed density may be generated due to the manufacturing method. When this density variation is very small, it is impossible to distinguish it from lens shading, uneven illumination of the light source, background noise of the image sensor, etc., and with conventional technology, it is possible to judge whether or not the density variation is very small. It was difficult.

  The present invention has been made in view of such a conventional problem, and the problem is that the S / N is emphasized by emphasizing minute density fluctuations generated in a colored film coated on a substrate with an optical filter. It is an object of the present invention to provide a substrate inspection apparatus and a substrate observation apparatus that improve the ratio and determine the quality of extremely small density fluctuations.

  The present invention relates to a camera having a CCD image sensor or a CMOS image sensor, a stage arranged perpendicular to the optical axis of the camera, a stage for gripping the board, an illumination means for illuminating the board from behind the stage, and a shutter of the camera An optical filter that transmits only a wavelength region with a low light transmittance of the substrate on the front surface of the imaging lens or / and illumination unit of the camera, and a recording unit that accumulates and stores an image obtained from the camera And a determination means for determining pass / fail based on the image.

  In the substrate inspection apparatus according to the present invention, the present invention further includes drive means and control means for moving the camera and the stage relative to each other so that the camera can pick up an arbitrary part of the substrate surface. A board inspection apparatus characterized by the above.

  Further, the present invention provides the substrate inspection apparatus according to the above invention, wherein the optical filter includes a plurality of optical filters that transmit only a wavelength region having a low light transmittance for each of the plurality of colored films applied to the substrate. The substrate inspection apparatus includes an optical filter exchange unit that switches each optical filter.

  Further, the present invention provides the substrate inspection apparatus according to the above invention, wherein the optical filter includes a plurality of optical filters that transmit only a wavelength region having a low light transmittance for each of the plurality of colored films applied to the substrate. A substrate inspection apparatus having a plurality of cameras corresponding to each optical filter and having an input switching means for switching an image to be input to the recording means.

  In the substrate inspection apparatus according to the present invention, the optical filter has an optical filter that transmits only a wavelength region having a low light transmittance for all of the plurality of colored films applied to the substrate. The board inspection apparatus.

  The present invention also provides a camera having a CCD image sensor or a CMOS image sensor, a stage arranged perpendicular to the optical axis of the camera, a stage for gripping the board, an illumination means for illuminating the board from behind the stage, and a camera The control means for controlling the shutter of the camera, the optical filter that transmits only the wavelength region with low light transmittance of the substrate, in front of the imaging lens or / and the illumination means of the camera, and the image obtained from the camera are presented to the observer And a display means for displaying the substrate.

  In addition, the present invention provides the substrate observation apparatus according to the above-described invention, having a drive unit and a control unit thereof that can move the camera and the stage relative to each other so that the camera can capture an arbitrary part of the substrate surface. Is a substrate observation apparatus characterized by the following.

  Further, the present invention provides the substrate observation apparatus according to the above invention, wherein the optical filter has a plurality of optical filters that transmit only a wavelength region having a low light transmittance for each of the plurality of colored films applied to the substrate. The substrate observing apparatus is characterized by having an optical filter exchanging means for switching each optical filter.

  Further, the present invention provides the substrate observation apparatus according to the above invention, wherein the optical filter has a plurality of optical filters that transmit only a wavelength region having a low light transmittance for each of the plurality of colored films applied to the substrate. A substrate observation apparatus having a plurality of cameras corresponding to each optical filter, and having an input switching means for switching an image input to the display means.

  Further, the present invention provides the substrate observation apparatus according to the above invention, wherein the optical filter includes an optical filter that transmits only a wavelength region having a low light transmittance for all of the plurality of colored films applied to the substrate. A substrate observation apparatus.

  As described above in detail, according to the substrate inspection apparatus and the substrate observation apparatus of the present invention, it is possible to eliminate the influence of lens shading, non-uniform illuminance of the light source, background noise of the image sensor, etc. It is possible to capture the minute density change that occurs in the image by improving the S / N ratio, and it is possible to perform the pass / fail judgment and observation of the minute density fluctuation.

  Hereinafter, embodiments of the present invention will be described in detail.

  The substrate inspection apparatus and the substrate observation apparatus according to the present invention are based on the principle that density variation is emphasized by using an optical filter that transmits only a wavelength region having a low light transmittance of the colored film applied on the substrate. . The principle will be described below.

  FIG. 1 is a cross-sectional view of a substrate coated with a colored film, showing a substrate (10), a colored film (11), and incident light (12a, 12b). Since the density variation of the colored film is caused by a minute change in the film thickness (T), the thickened portion (ΔT) in FIG. 1 corresponds to the density variation.

When light (12a) having a low transmittance of the colored film is incident on the colored film applied to the substrate, the light is mostly absorbed and attenuated, as shown in FIG. The amount of light that comes out is (d ₁ ) and (d ′ ₁ ).

On the other hand, when light (12b) having a high transmittance is incident, as shown in FIG. 1 (b), the light is hardly attenuated, and the amount of the emitted light is (d ₂ ) and (d ' ₂ ).

In FIGS. 1A and 1B, since the slope of the line representing the light amount represents the attenuation rate of the light amount, the larger the attenuation rate, the greater the influence on the transmitted light amount, even with the same film thickness change. I understand that Therefore, since the light quantity ratio between the density fluctuation part and the normal part is d ′ ₁ / d ₁ > d ′ ₂ / d ₂ , it can be seen that density fluctuation is emphasized by using light having a wavelength with low transmittance.

Expressed by the equation, if the transmittance per unit thickness is D (0 <D <1) and the film thickness is T, the transmitted light amount in the normal part is D ^T , and the transmitted light amount in the density variation part is D ^{T +} Δ ^T , and accordingly the ratio of the amount of transmitted light ^{D T + Δ T / D T} = DΔ T , and when the film thickness variation [delta] T is constant (0 <ΔT <1), the ratio of the amount of transmitted light greatly deviates from 1 as D is small, that density variation Will be emphasized.

  It can also be seen that when the film thickness fluctuation, which was difficult to detect with the conventional method, is very small (0 <ΔT << 1), D suddenly deviates greatly from 1 when D takes a value very close to 0. Therefore, the key to improving the S / N ratio is to use a filter that transmits only a wavelength with a very low transmittance.

  In the above description, incident light has a specific wavelength, but the incident light includes light of various wavelengths such as white light, and even when only a specific wavelength is selected by an optical filter on the camera side. Exactly the same argument holds.

  When the substrate is large relative to the camera field of view and it is impossible to capture images in a lump, the driving means that can move the camera and the stage relative to each other so that the camera can image any part of the substrate surface and its control After moving the drive means, the shutter of the camera is turned off and the image is stored in the recording means or output to the display means so that the entire substrate can be inspected or observed.

  FIG. 7A illustrates an example in which a colored film is uniformly applied to the entire surface of the substrate, and FIG. 7B illustrates an example in which the colored film is applied to the entire surface of the substrate in a multi-faceted state. FIG. When there are multiple colored films, multiple influences such as lens aberration and light source shading are equal on each surface by driving the driving means so that each colored film is at the center of the field of view and sequentially inspecting or observing. More desirable results can be obtained.

  In addition, when the substrate is composed of a plurality of colored films, a plurality of optical filters that transmit only a wavelength region having a low light transmittance are provided for each of the colored films, and the images are sequentially switched by an optical filter replacement unit. Or a plurality of optical filters and a plurality of cameras corresponding to the respective optical filters are provided, and images are sequentially collected while switching images by an input switching unit that switches images input to the recording unit or the display unit.

  According to the substrate inspection apparatus and the substrate observation apparatus of the present invention, the S / N ratio is improved by emphasizing the density fluctuation generated in the colored film applied on the substrate, and the shading of the lens, the illuminance nonuniformity of the light source, and the image sensor Therefore, it is possible to determine whether or not the density fluctuation is very good and to observe it without the influence of the background noise.

  Hereinafter, the present invention will be described in detail by way of examples.

  FIG. 2 is a perspective view illustrating the concept of the substrate inspection apparatus according to the first embodiment. The driving means (20) disposed above the substrate so that the camera (22) can be moved to an arbitrary position in the plane of the substrate (23) is a two-axis orthogonal robot arm that can move in the XY2 directions. Of course, depending on the relationship between the camera field of view and the substrate size, it is possible to adopt a configuration without a driving means.

  A camera is fixed to the substrate on the slider of the driving means, and an optical filter (21) is fixed to the tip of the camera lens.

  On the other hand, the substrate is fixed on a stage (not shown), and further illuminated by illumination means (light source) (24) below the substrate.

  In the first embodiment, the optical filter is on the camera side, but it can be installed on the light source (24).

  FIG. 3 is a graph showing the wavelength-specific transmission characteristics of the colored film (M1) and the optical filter (F1) in Example 1. Since the colored film has a transmittance of about 600 nm or less and low transmittance, a blue dichroic filter that transmits only light of 400 to 500 nm is used as the optical filter. Of course, the selection of the optical filter is not limited to this, and any optical filter can be selected as long as it transmits only a wavelength having a low transmittance of the colored film.

  FIG. 4 is an explanatory diagram illustrating a flow of inspection apparatus control according to the first embodiment. By inputting the position and size of the colored film to the control means, the control means calculates the amount of movement of the driving means and outputs a movement command to the driving means.

  Thereafter, the control means releases the shutter of the camera, and the image data is stored in the recording means. In the first embodiment, the image size is single color data of 640 × 480 dots and 256 gradations per dot. When notified that the image has been saved, the image processing means reads this image and performs pass / fail judgment processing. At this time, the substrate observation apparatus can be configured by sending the image data to the display means instead of the recording means.

  FIG. 5 is a perspective view illustrating the concept of the substrate inspection apparatus according to the second embodiment. In the second embodiment, the substrate, driving means, camera, stage, and light source are exactly the same as in the first embodiment, but an optical filter switching means (55) is provided on the front surface of the lens of the camera, and the two optical filters are switched. It is fixed on the top.

  FIG. 6 is a graph showing the transmission characteristics by wavelength of the colored film and the optical filter in Example 2. Since the colored film 1 (M2) has a transmittance of about 600 nm or less and low transmittance, a green dichroic filter that transmits only light of 500 to 600 nm is employed as the optical filter 1 (F2).

  Further, since the colored film 2 (M3) has a transmittance of about 500 nm or less and about 600 nm or more, the optical filter 2 (F3) employs a red sharp cut filter that transmits only light of 600 nm or more.

  By selecting an optical filter that matches the wavelength range where the transmittance of the other colored film is high in this way, even when multiple colored films are formed in layers, only the density fluctuations that occur in one colored film are separated. Can be inspected or observed.

  On the other hand, when the colored films are alternately arranged, the light from the other colored film reaches the camera in the almost normal state when the optical filter is selected as described above. Or there is a concern that it may adversely affect observation.

  In this case, it is only necessary to use the optical filter 3 (F4) that transmits only light with low transmittance in either colored film. In the case of FIG. 6, an optical filter that transmits only light of about 500 nm or less may be used.

  By inputting the position and size of the colored film to the control means, the control means calculates the amount of movement of the driving means and outputs a movement command to the driving means.

  Thereafter, the control means releases the shutter of the camera, and the image data is stored in the recording means. Subsequently, after the optical filter is switched by the optical filter switching means, the control means again releases the shutter of the camera, and the image data of the other colored film is stored in the recording means.

  In the second embodiment, the image size is 640 × 480 dots, and there are two pieces of monochrome data with 256 gradations per dot. When notified that the image has been saved, the image processing means reads this image and performs pass / fail judgment processing. At this time, the substrate observation apparatus can be configured by sending the image data to the display means instead of the recording means.

It is sectional drawing of the board | substrate with which the colored film was apply | coated. It is a perspective view which shows the concept of the board | substrate inspection apparatus in Example 1. FIG. 4 is a graph showing transmission characteristics by wavelength of a colored film and an optical filter in Example 1. It is explanatory drawing which shows the flow of inspection apparatus control of Example 1. FIG. It is a perspective view which shows the concept of the board | substrate inspection apparatus in Example 2. FIG. It is a graph showing the transmission characteristic according to wavelength of the colored film in Example 2, and an optical filter. (A) is explanatory drawing by which the colored film was apply | coated to the whole surface of a board | substrate by 1 surface.

  (B) is explanatory drawing by which the colored film was apply | coated to the whole surface of the board | substrate in the multi-faceted state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 23 ... Substrate 11 ... Colored film 12a, 12b ... Incident light 20 ... Driving means 21 ... Optical filter 22 ... Camera 24 ... Illuminating means (light source)
55... Optical filter switching means F1... Transmittance according to wavelength of optical filter in Example 1 F2... Optical filter 1 in Example 2
F3: Optical filter 2 in Example 2
F4: Optical filter 3 in Example 2
M1 ... Transmittance by wavelength of colored film in Example 1 M2 ... Colored film 1 in Example 2
M3 Colored film 2 in Example 2

Claims (10)

  A camera having a CCD image sensor or a CMOS image sensor, a stage that is disposed perpendicular to the optical axis of the camera, a stage that grips the substrate, illumination means that illuminates the substrate from behind the stage, and a control that controls the shutter of the camera Means, an optical filter that transmits only the wavelength region having a low light transmittance of the substrate, in front of the imaging lens or / and the illumination means of the camera, a recording means for storing and storing images obtained from the camera, and the image A substrate inspection apparatus comprising: determination means for determining pass / fail based on the above.   2. The substrate inspection apparatus according to claim 1, further comprising a driving unit capable of moving the camera and the stage relative to each other so that the camera can take an image of an arbitrary part within the substrate surface and a control unit thereof.   As the optical filter, for each of the plurality of colored films applied to the substrate, the optical filter includes a plurality of optical filters that transmit only a wavelength region having a low light transmittance, and includes an optical filter replacement unit that switches each optical filter. The substrate inspection apparatus according to claim 1, wherein the substrate inspection apparatus is characterized.   As the optical filter, each of the plurality of colored films applied to the substrate has a plurality of optical filters that transmit only a wavelength region with low light transmittance, and has a plurality of cameras corresponding to each optical filter, 4. The substrate inspection apparatus according to claim 1, further comprising an input switching unit that switches an image to be input to the recording unit.   3. The substrate inspection according to claim 1, wherein the optical filter has an optical filter that transmits only a wavelength region having a low light transmittance for all of the plurality of colored films applied to the substrate. apparatus.   A camera having a CCD image sensor or a CMOS image sensor, a stage that is disposed perpendicular to the optical axis of the camera, a stage that grips the substrate, illumination means that illuminates the substrate from behind the stage, and a control that controls the shutter of the camera Means, an optical filter that transmits only the wavelength region with low light transmittance of the substrate, and a display means for presenting an image obtained from the camera to the observer in front of the imaging lens or / and the illumination means of the camera. A substrate observation apparatus.   6. The substrate observation apparatus according to claim 5, further comprising a driving unit capable of moving the camera and the stage relative to each other and a control unit thereof so that the camera can image any part of the substrate surface.   As the optical filter, for each of the plurality of colored films applied to the substrate, the optical filter includes a plurality of optical filters that transmit only a wavelength region having a low light transmittance, and includes an optical filter replacement unit that switches each optical filter. The board | substrate observation apparatus of Claim 5 or Claim 6 characterized by the above-mentioned.   As the optical filter, each of the plurality of colored films applied to the substrate has a plurality of optical filters that transmit only a wavelength region with low light transmittance, and has a plurality of cameras corresponding to each optical filter, The substrate observation apparatus according to claim 5, further comprising an input switching unit that switches an image to be input to the display unit.   7. The substrate observation according to claim 5, wherein the optical filter has an optical filter that transmits only a wavelength region having a low light transmittance for all of the plurality of colored films applied to the substrate. apparatus.

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