KR100678821B1 - Inspection apparatus - Google Patents

Abstract

As the film thickness of the transparent conductive film pattern produced on the substrate for LCD or the like becomes thinner, the contrast at the pattern edge portion decreases, making measurement difficult in the prior art. The contrast of such a transparent conductive film part and the other part is increased, and the technique of measuring the dimension of the transparent conductive film pattern with small film thickness easily is provided.

The lighting unit is provided with a lamp for generating light having a high luminance in an area below visible light and an optical filter for blocking long wavelength components above visible light, thereby increasing the contrast of the transparent conductive film portion and other portions, and having a small film thickness. Measurement of the dimensions of the conductive film pattern was easily realized.

Description

Inspection device {INSPECTION APPARATUS}

1 is a block diagram showing a schematic configuration of a dimension measuring apparatus of a first embodiment of the present invention;

2 is a view showing an example of the spectrum of the light generated by the light source used in the illumination unit of the first embodiment of the present invention;

3 is a transmission characteristic diagram of an optical filter used in the illumination unit of the first embodiment of the present invention;

4 is a view showing an example of a transmission characteristic of a transparent conductive film of a sample;

5 is a view for explaining an example of the effect when using the present invention;

6 is a block diagram showing a schematic configuration of a dimension measuring apparatus according to a second embodiment of the present invention;

7 is a transmission characteristic diagram of an optical filter used in the illumination unit of the second embodiment of the present invention;

8 is a block diagram showing a schematic configuration of a conventional measuring device;

9 is a view showing an example of a spectrum of light generated by a light source used in a conventional lighting unit.

Explanation of symbols for the main parts of the drawings

1 ': lighting unit 2: optical fiber

3: floodlight 4, 4 ': lighting unit

5: optical fiber 6: transmission light head

7: revolver 8: objective

9, 9 ': sample 10: autofocus unit

11, 12: Lens 13: Auto Dimmer Unit

14: CCD camera 15: image processing unit

16, 16 ': optical filter 17, 17': filter switching mechanism

20: mirror 21, 22: half mirror

23, 23 ': 24, 24': lamp.

This invention is used for the inspection apparatuses, such as a dimension measuring apparatus, which measures the dimension of a transparent conductive film pattern by enlarging the dimension of the pattern formed on the board | substrate with a microscope.

A dimension measuring apparatus of a substrate (for example, an LCD (Liquid Crystal Display) substrate) is used to magnify a pattern image obtained by irradiating an illumination light onto a pattern formed on a substrate (sample) such as glass with a microscope, and the image is CCD (Charge Coupled Device). An inspection apparatus for measuring dimensions by image-processing a pattern image obtained by imaging with a camera.

As a method of irradiating illumination light with a sample, the reflection illumination method which irradiates coaxial fall-off from a microscope, and processes the image obtained from the reflected light, and the illumination light from the back side of a sample facing a microscope, There is a transmission illumination system for processing an image obtained. However, as the measurement of the size of an LCD substrate, it is generally performed to include means for realizing both illumination methods and to perform the discrimination according to the pattern to be inspected.

In the manufacturing process of an LCD substrate, the dimension of the resist film pattern, the produced metal film, or the transparent or translucent film | membrane for producing the target pattern is measured.

Dimensional measurement of these patterns was realized by the structure shown in FIG. 8 as a prior art. 8 is a block diagram showing a schematic configuration of a conventional measuring device. (1) is the illumination unit of the reflection illumination method, (3) is the floodlight tube, (2) is the optical fiber for guiding the light output from the illumination unit (1) to the floodlight tube (3), (4) is of the transmission illumination method The illumination unit, (6) is a transmission light head, (5) is an optical fiber for guiding the light output from the illumination unit (4) to the transmission light head (6), (7) is a revolver, (8) an objective lens, ( 9 is a sample, 10 is a laser autofocus unit, 11 and 12 are lenses, 13 is an auto-dimming unit, 14 is a CCD camera, 15 is an image processing unit, and 20 is a Is a mirror in the transmissive illumination head 6, 21 is a half mirror in the floodlight tube 3, 22 is a half mirror in the laser autofocus unit 10, 23 is a lamp of the illumination unit 1, Denoted at 24 is a lamp of the illumination unit 4. In addition, the microscope includes at least the illumination units 1 and 4, the optical fibers 2 and 5, the floodlight tube 3, the transmission illumination head 6, the mirror 20 installed in the transmission illumination head 6, and the revolver 7 ), A sample stand for fixing the objective lens 8 installed in the revolver 7, the laser autofocus unit 10, the half mirrors 21 and 22, the lenses 11 and 12, and the sample 9 (not shown) It is roughly composed of

In FIG. 8, light irradiated from the illumination unit 1 for coaxial fall illumination is irradiated to the sample 9 via the optical fiber 2 via the half mirror 21 and the objective lens 8 of the floodlight tube 3. do. In addition, the lamp 23 in the illumination unit 1 is a lamp which produces white light, such as a halogen lamp.

The light reflected from the sample 9 passes through the half mirror 21 of the floodlight tube 3 and the half mirror 22 of the laser autofocus unit 10, and then passes through the lenses 11 and 12 to form a CCD camera. It forms in the imaging surface of (14).

The laser auto focus unit 10 processes the reflected light reflected from the sample 9 to automatically focus the microscope. In addition, an automatic dimming unit 13 is provided between the microscope and the CCD camera 14, and the automatic dimming unit 13 controls the amount of light incident on the CCD camera 14 by a certain amount.

The revolver 7 is also used to change the magnification by changing the objective lens 8.

In the case of measuring by the transmission illumination method, the light irradiated from the illumination device 4 for transmission illumination is irradiated onto the sample 9 via the optical fiber 5 via the mirror 20 of the transmission illumination head 6. In addition, the lamp 24 in the illumination unit 4 is a lamp which produces white light, such as a halogen lamp, for example.

The irradiated light passes through the transparent or translucent portion of the sample 9, enters the objective lens 8, and forms an image on the CCD camera 14 as described above.

The formed image is picked up by the CCD camera 14, converted into an image signal, and output to the image signal image processing unit 15 as an image of the specimen 9.

The video signal image processing unit 15 performs image processing on the input image and measures the dimensions of the predetermined pattern. In addition, the illumination units 1 and 4, the floodlight tube 3, the laser auto focus unit 10, the revolver 7 and the auto dimmer unit 13 are connected to the image processing unit 15 for changing the measurement conditions. Is controlled by

In this configuration, the halogen lamps of the illumination units 1 and 4 have a continuous spectrum close to the white light as shown in Fig. 9 and inexpensive halogen lamps are generally used. FIG. 9 is a diagram showing an example of a spectrum of light generated by a light source used for the illumination lamps 23 or 24 of the illumination unit 1 or 4. FIG.

The above-mentioned technique is described in patent document 1, for example.

 (Patent Document 1) Japanese Patent Application Laid-Open No. 2003-279318

For example, a transparent conductive film (transparent conductive film) is formed as a pattern generated in a substrate such as an LCD, but in a pattern of a transparent material in such visible light region, light reflected from the pattern edge portion of the transparent conductive film is incident on a microscope. The measurement was performed at the pattern edge part using the action of darkening instead. In this case, when the transparent conductive film was thick, the contrast at the pattern edge portion was large, and thus could be sufficiently measured. However, as the transparent conductive film becomes thinner due to recent material cost reduction, miniaturization of patterns, etc., the contrast at the pattern edge portion decreases, making measurement difficult in the prior art.

An object of the present invention is to solve the problems described above, to increase the contrast between the transparent conductive film portion and other portions, and to easily realize the dimensional measurement of the transparent conductive film pattern having a small film thickness.

In order to achieve the above object, the inspection apparatus according to the first aspect of the present invention is an inspection apparatus for measuring the dimensions of the pattern formed on the substrate by magnifying under a microscope, the lamp having a spectrum of the wavelength range of visible light or less And an optical filter for blocking light components in a wavelength region longer than visible light.

The above-described optical filter according to the first aspect transmits only light having a wavelength of approximately 600 nm or less.

The above-described lamp according to the first aspect has at least one bright line at a wavelength of approximately 600 nm or less.

The above-described inspection apparatus according to the first aspect uses at least one of reflection light and transmission light.

The lamp according to the first aspect has at least one bright line around 400 nm, 450 nm, 550 nm, 580 nm.

The optical filter according to the first aspect has at least one bright line.

Moreover, the inspection apparatus which concerns on the 2nd aspect of this invention is the inspection apparatus which measures the dimension by enlarging the dimension of the pattern formed on the board | substrate with a microscope, Comprising: The lamp which has a bright line in a predetermined wavelength range, And an optical filter passing through the light component.

The predetermined wavelength region which the above-described optical filter according to the second aspect passes at least overlaps with the predetermined wavelength region in which the lamp has a bright line.

A plurality of the lamps and the optical filter according to the second aspect are provided, and the lamps are switched to any one lamp or any one optical filter depending on the type of the sample to be inspected.

The inspection apparatus according to the second aspect uses at least one of reflection light and transmission light.

The embodiment of the present invention utilizes the property of decreasing the transmittance of the transparent conductive film over a short wavelength range of visible light or less, thereby limiting the light irradiated from the illumination unit to a wavelength range of decreasing the transmittance of the transparent conductive film. The contrast between the part and the other parts is increased to allow the dimensional measurement.

To this end, the embodiment of the present invention is changed from a lamp having a continuous spectrum to a mercury xenon lamp or a metal halide lamp having a bright spectrum, and furthermore, the transmittance of the transparent conductive film in the bright spectrum generated from the lamp is lowered. The optical filter which transmits only the wavelength range to add is added.

For example, when a mercury xenon lamp or a metal halide lamp is used, when the transmission characteristic of the transparent conductive film follows the graph I of FIG. 4, light having a wavelength of around 450 nm where the transmittance decreases and bright lines appear, or is transparent When the transmission characteristic of the conductive film follows the graph II of Fig. 4, light having a wavelength of about 550 nm in which the transmittance is lowered and bright lines appear is used.

<Example 1>

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5.

1 is a block diagram showing a schematic configuration of a dimension measuring apparatus according to a first embodiment of the present invention. 2 is a figure which shows an example of the spectrum of the light which the lamp (light source) used for the illumination units 1 'and 4' which concerns on 1st Example generate | occur | produces. 3 is a transmission characteristic diagram of the optical filter used for the lighting units 1 'and 4' according to the first embodiment. 4 is a figure which shows an example of the permeation | transmission characteristic of the transparent conductive film of the sample 9. As shown in FIG. 5 is a figure for demonstrating the effect at the time of using this invention.

In Fig. 1, the same reference numerals are given to units having the same functions as those of Fig. 8 in the related art. In addition, 1 'is the illumination unit of the reflective illumination method, 4' is the illumination unit of the transmission illumination method, 23 'is the lamp of the illumination unit 1', 24 'is the illumination unit 4 Lamp 16 ', 16 is an optical filter, and 17 is a filter changing mechanism.

The lighting units 1 'and 4' are lamps 23 having a bright line in a wavelength region (for example, about 405 nm, about 436 nm, 546 nm, and 578 nm) between about 400 nm and 600 nm, such as a mercury xenon lamp or a metal halide lamp. 24, and an optical filter 16 for transmitting only the wavelength region in which the transmittance of the transparent conductive film decreases (e.g., blocking a wavelength longer than 450 nm) is disposed near the exit portion of the illumination unit. The optical filter 16 is mounted on the filter changing mechanism 17, and the optical filter 16 is replaced with the optical filter 16 when measuring the size of the pattern formed of the transparent conductive film having the transmission characteristics as shown in the graph I of FIG.

When the light irradiated from the lamp of the illumination unit 1 'or 4' passes through the optical filter 16, bright light is emitted in a wavelength range shorter than the wavelength of 450 nm, depending on the transmission characteristics of the optical filter shown in FIG. Only light having is transmitted. In this way, the light irradiated from the illumination unit 1 'is irradiated to the sample 9 through the optical fiber 2 via the half mirror 21 of the light emitting tube 3 or irradiated from the illumination unit 4'. Light is irradiated to the sample 9 via the optical fiber 5 via the mirror 20 of the transmission illumination head 6.

The irradiated light is reflected light from the sample 9 if it is coaxial fall illumination, and transmitted light from the sample 9 is incident on the objective lens 8 if it is transmitted light, and the CCD camera 14 is applied to the CCD camera 14 as described in the conventional example. It is missing.

The pattern image of the specimen 9 picked up by the CCD camera 14 is output to the image processing unit 15 as an image signal, and the image processing unit 15 executes image processing based on the input image signal, thereby Measure the dimensions.

Here, the laser auto focus unit 10, the auto dimmer 13, the revolver 7, the objective lens 8, the half mirrors 21 and 22, the lenses 11 and 12, and the image processing unit 15 are It works like the conventional example. The control target of the image processing unit 15 is controlled by the filter changing mechanism 17 in addition to the conventional example.

This operation will be described below.

As shown in Fig. 4, the transparent conductive film has a transmissive characteristic of approximately 80% in the visible region, but rapidly deteriorates in the wavelength shorter than the visible region.

Therefore, in the reflection illumination method, when the transparent conductive film is present on the metal film with high reflectance, when only the light having a wavelength range shorter than 450 nm is irradiated from the top of the sample 9, the portion without the transparent conductive film ( The metal film portion) has a large amount of reflected light due to the high reflectance, but the transparent conductive film portion has a large amount of reflected light because the irradiated light is once attenuated while incident on the transparent conductive film and then reflected on the metal film and exits through the conductive film again. It is low (it becomes low reflectance).

For this reason, the contrast difference between the part without a transparent conductive film and the transparent conductive film part becomes large, and an edge can be detected and a dimension measurement based on the contrast difference of a pattern edge part.

When the transparent conductive film is directly present on the glass substrate, the reflectance itself of the glass substrate is low, but since the portion where the transparent conductive film is present becomes darker in the same principle as above, the edge is detected from the difference in contrast between the pattern edges and the dimension. Measurement can be performed. That is, since there is a glass substrate under the transparent conductive film, even if the amount of light reflected from the glass substrate is the same on both sides, the amount of light passing through the transparent conductive film and emitted through the transparent conductive film has a transmittance of 100 compared to the amount of light directly incident on the glass substrate and reflected. It becomes small because it is less than% (80% also in a visible region).

In the case of the transmission illumination system, when only light in a wavelength range shorter than 450 nm is irradiated from the lower part of the sample 9, the glass base portion is bright because it has high transmission characteristics, but the portion where the transparent conductive film exists is transparent It is dark because it is low. For this reason, the contrast difference between the part without a transparent conductive film and the transparent conductive film part generate | occur | produces, and an edge can be detected from the contrast difference of a pattern edge part, and dimension measurement is possible.

5, the image obtained by implementing this invention is compared with the image obtained by the prior art, and it demonstrates. All the samples for acquiring an image use the same thing.

In FIG. 5, FIG. 5 (a) is an image of the case of using a conventional halogen lamp in the lighting unit, and the same sample is used. The contrast is completely different between the transparent conductive film on the metal film and the transparent conductive film on the glass substrate. In this case, it is difficult to detect the edge and perform the dimensional measurement. FIG. 5 (b) is an image when a metal halide lamp is used for the lighting unit. Compared with FIG. 5 (a), the contrast of the transparent conductive film on the metal film is generated. However, the contrast between the transparent conductive film on the glass substrate is almost the same. Does not occur. For this reason, it is difficult to measure an edge by detecting an edge. Fig. 5C is an image obtained by using a metal halide lamp for the illumination unit and adding an optical filter. The contrast difference occurs in both the transparent conductive film on the metal film and the transparent conductive film on the glass substrate, and it is easy to realize the dimension measurement by detecting the edge from the contrast difference of the pattern edge part.

The image of FIG. 5C is an example in which an illumination unit incorporating a metal halide lamp is combined with an optical filter having transmission characteristics shown in FIG. 3, but is not limited thereto. For example, when an optical filter that transmits only the ultraviolet region is used and a mercury xenon lamp is used as the illumination unit, the illumination of the ultraviolet region is irradiated, so that the transmission characteristic of the transparent conductive film is further lowered, so that an image with more contrast can be obtained. You can get it.

As a light source, although it is also possible to cut out the light of the lamp which has a continuous spectrum with an optical filter, a specific wavelength can be considered, but in this case, there exists a fault that a light quantity is insufficient. However, when a lamp having a bright line is used, light of a specific wavelength can be output efficiently, and the amount of light required for inspection can be obtained.

In addition, in the above-described embodiment, in particular, there are many parts described without distinguishing the reflected light and the transmitted light, but the reflected light and the transmitted light may be inspected at the same time or may be inspected using either.

In addition, the filter changing mechanism 17 may be used by inspecting the case of using the optical filter for blocking the light in the longer wavelength region or more than the visible light and using the optical filter for blocking the light. In addition, a plurality of cutoff wavelength regions of the optical filter may be provided, changed and controlled to inspect the combination of the regions.

In addition, it is also possible to test by using a combination of an optical filter and a combination of reflected and transmitted illumination.

<Example 2>

A second embodiment according to the present invention will be described with reference to graphs II, 6 and 7 of Figs. Fig. 4 is a transmission characteristic diagram of the transparent conductive film of the sample 9 'used in the second embodiment (see Fig. 6), and Fig. 6 is a block diagram showing the schematic configuration of the dimension measuring apparatus of the second embodiment. Fig. 7 is a transmission characteristic diagram of the optical filter 16 '(see Fig. 6) according to the second embodiment.

The second embodiment uses a sample 9 'whose transparent conductive film has a transmission characteristic according to the graph II of Fig. 4, and the first embodiment employs an optical filter 16 which transmits only light having a wavelength of approximately 450 nm or less. On the other hand, the same applies except that the optical filter 16 'which transmits only light in the wavelength region around 550 nm is employed. Therefore, in the following description of the second embodiment, the same parts as the first embodiment will be omitted.

Referring to Fig. 1, the optical filter 16 'is disposed near the exit of the illumination unit 1' or 4 'by the filter changing mechanism 17'.

With this configuration, when the light irradiated from the lamp 23 'or 24' of the lighting unit 1 'or 4' passes through the optical filter 16 ', the optical filter shown in FIG. According to the transmission characteristics, only light having a bright line in the wavelength region near the 550 nm wavelength is transmitted. In this way, the light irradiated from only the illumination unit 1 'near the wavelength of 550 nm is irradiated to the sample 9' through the optical fiber 2, through the half mirror 21 of the light-emitting tube 3 or the illumination unit. Light irradiated from 4 'is irradiated to the sample 9' via the optical fiber 5 via the mirror 20 of the transmission illumination head 6.

The irradiated light is reflected light from the sample 9 'if it is coaxial fall illumination, and transmitted light from the sample 9' is incident on the objective lens 8 if it is transmitted light, and as described in the conventional example, the CCD camera ( It is missing in 14).

The pattern image of the specimen 9 'picked up by the CCD camera 14 is output to the image processing unit 15 as a video signal, and the image processing unit 15 executes image processing based on the input video signal, Measure the dimensions of the pattern.

Here, the laser auto focus unit 10, the auto dimmer 13, the revolver 7, the objective lens 8, the half mirrors 21 and 22, the lenses 11 and 12, and the image processing unit 15 are It works similarly to the embodiment of FIG.

This operation will be described below.

Since the transmission characteristic of the transparent conductive film follows the graph II of FIG. 4, when the transparent conductive film is present on the metal film having high reflectance, only light in the wavelength region around 550 nm is irradiated from the top of the sample 9 ′. The part without the conductive film (metal film part) has a large amount of reflected light due to the high reflectance, but the transparent conductive film part is attenuated while the irradiated light is reflected on the metal film once it enters the transparent conductive film and then exits through the conductive film. Therefore, the amount of reflected light is small (it becomes a low reflectance).

For this reason, the contrast difference between the part without a transparent conductive film and the transparent conductive film part becomes large, and an edge can be detected and a dimension measurement based on the contrast difference of a pattern edge part.

If the transparent conductive film is directly present on the glass substrate, the reflectance itself of the glass substrate is low, but since the portion where the transparent conductive film is present becomes darker in the same principle as above, the edge is measured by detecting the edge from the contrast difference of the pattern edge portion. can do.

When only the light in the 550 nm wavelength region is transmitted and irradiated from the lower portion of the sample 9 ', the glass substrate portion is bright because it has high transmission characteristics, but the portion where the transparent conductive film exists is dark because of its low transmittance. For this reason, the contrast difference between the part without a transparent conductive film and the transparent conductive film part generate | occur | produces, and an edge can be detected from the contrast difference of the pattern edge part, and dimension measurement can be performed.

In the above embodiment, the change of the light source and the filter in the short wavelength region of visible light or less has been described. However, in addition to the above embodiment, a combination of a light source having a bright line in various wavelength regions and a filter which does not pass light in a wavelength region shorter or longer than visible light or a filter passing light in a predetermined wavelength region are conducted. Depending on the kind of film, at least one of a light source or a filter can be changed and used.

Moreover, it is applicable not only to a transparent conductive film but also to the film pattern made by various materials and various manufacturing methods.

According to the present invention, since the transparent conductive film which is not obtained by the prior art can be visualized, an edge can be measured by measuring the edge from the contrast difference of the pattern edge part of the transparent conductive film which cannot be made by the prior art. This invention is effective for the dimension measurement of board | substrates, such as an LCD substrate which has a transparent conductive film pattern.

Claims (10)

In the inspection apparatus for measuring the size of the pattern formed on the substrate by magnifying under a microscope, A lamp having a spectrum in the wavelength region below visible light, Characterized by comprising an optical filter for blocking light components in the wavelength region longer than visible light Inspection device. The method of claim 1, The optical filter transmits only light having a wavelength of about 600 nm or less. Inspection device. The method according to claim 1 or 2, The lamp is a lamp having at least one bright line at a wavelength of approximately 600 nm or less  Inspection device. The method according to claim 1 or 2, Inspected using at least one of reflected light and transmitted light Inspection device. The method of claim 3, wherein The lamp has at least one bright line around 400 nm, 450 nm, 550 nm, and 580 nm. Inspection device. The method of claim 5, The optical filter transmits light having a wavelength having at least one bright line. Inspection device. In the dimension measuring apparatus which measures the dimension by enlarging the dimension of the pattern formed on the board | substrate with a microscope, A lamp having bright lines in a predetermined wavelength range, And an optical filter for passing the light component in a predetermined wavelength range. Inspection device. The method of claim 7, wherein The predetermined wavelength region that the optical filter passes at least overlaps with the predetermined wavelength region where the lamp has a bright line. Inspection device. The method according to claim 7 or 8, And a plurality of the lamps and the optical filter, and change to any one lamp or any one optical filter according to the type of specimen to be inspected. Inspection device. The method according to claim 7 or 8, Inspected using at least one of reflected light and transmitted light Inspection device.

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