JPH0587763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for detecting the position of a transparent conductive film (hereinafter referred to as an ITO film) formed on a glass substrate.

(Prior Art) Conventionally, there have been roughly two types of methods for detecting the position of an ITO film deposited or sputtered on a glass substrate.

One method is to scan the surface of a substrate such as glass using a laser beam.
This method detects the displacement of the laser beam reflected from the ITO film surface and the phase disturbance in the contour of the ITO film pattern, converts it into an electrical signal, and detects the ITO film pattern. The other method uses an optical microscope to apply transmitted illumination or reflected illumination to the entire surface of the glass substrate and ITO film pattern.
This method detects the ITO film pattern by converting the contrast between light and darkness with the film pattern into an electrical signal.

(Problems to be Solved by the Invention) However, the conventional system has the following drawbacks.

(1) Disadvantages of the laser beam scanning method: Because it requires a complicated optical system structure, the equipment is expensive and requires a long time to make adjustments and set optimal conditions.

(2) Disadvantages of optical microscopy The contrast between light and dark is small because the transparency of the substrate plate, such as glass, and the ITO film are very similar. Therefore, when converted into an electrical signal, it is difficult to distinguish it from noise, and it is easy to misrecognize it. next,
This method is affected by changes in optical properties due to the thickness and composition of the ITO film. Furthermore, if a photosensitive agent such as photoresist is coated on a substrate plate such as glass or an ITO film pattern,
The contrast between the pattern of the ITO film and the glass substrate was almost zero due to the high transparency of the ITO film, and therefore it was impossible to recognize the pattern of the ITO film.

The technical problem of the present invention is to solve the drawbacks of the above-mentioned prior art, to provide a relatively inexpensive device, and to
It is an object of the present invention to provide a method and apparatus for detecting the position of a transparent conductive film, which enables clear recognition of an ITO film pattern.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and the method of the present invention requires recognition of a transparent conductive film pattern formed on a transparent glass substrate. This is a position detection method for a transparent conductive film in which a conductive film pattern on the workpiece is coated with a photoresist film, and the photographed image is processed using an optical microscope that uses monochromatic light as an illumination system. The center wavelength is set in the range of 380 to 1200 nm, and the wavelength width is selected to be variable in steps or continuously in the range of 0.1 to 250 nm.

Furthermore, the apparatus of the present invention includes a transparent conductive film pattern formed on a transparent glass substrate as a workpiece to be detected, a means for coating the conductive film pattern with a photoresist film, and a means for coating the coated workpiece to be detected. An optical microscope is installed on the sample mounting table and uses monochromatic light as an illumination system, a video camera is attached to the optical microscope to take an image of the workpiece to be detected, and an output signal of the video camera is inputted and converted into an output signal. Therefore, the present invention is a transparent conductive film position detecting device comprising an image processing device that performs feedback control of the light source of the illumination system of the optical microscope. Furthermore, the monochromatic light is output light from a monochromator or output light through a white light interference filter.

(Function) The present invention uses an optical microscope with a monochromatic illumination system, and uses the interference effect between the glass substrate part and the resist film on the ITO film to cause the intensity of the reflected light to vary, thereby increasing the contrast. The results are good and the ITO film pattern can be recognized.

(Example) Hereinafter, an example according to the present invention will be described with reference to the drawings. Prior to describing embodiments, the principle of the system of the present invention will be described.

The inventor has created a pattern recognition method that is effective for recognizing transparent ITO films deposited or sputtered on transparent glass substrates.

Figure 1 is a characteristic diagram of the spectral reflectance measured using an optical microscope for a photoresist film coated on a transparent glass substrate, and Figure 2 is a characteristic diagram of the spectral reflectance of a photoresist film coated on a transparent glass substrate.
FIG. 2 is a characteristic diagram of spectral reflectance measured using an optical microscope for a photoresist film coated on an ITO film pattern.

Conventionally, optical microscopes emit light that is close to white, so the average value of reflectance over the entire illumination wavelength becomes the reflected light from the glass surface and the ITO film pattern, which appears as a contrast between bright and dark. However, in Figure 2, each of the irradiated monochromatic lights interferes with each other due to the phase of the light reflected on the photoresist surface and the light reflected on the ITO film pattern surface, and as a result, depending on the wavelength, brightness and darkness are generated. is occurring.

Therefore, when considering the entire wavelength range of the irradiated light source, the average value of the reflectance is extremely close to the reflectance shown in Figure 1, and the reflected light from the photoresist surface and
The contrast between brightness and darkness of the reflected light on the ITO film surface was almost zero. Even if the contrast could be varied in the electrical signal, it would be unfavorable for pattern recognition. Accurate pattern recognition has been impossible because it is nearly impossible to distinguish contrast due to noise components, such as uneven coating of photoresist, etching residue of patterns, dust, dirt, scratches, etc. Furthermore, even if the noise component could be ignored, stable pattern recognition was not possible due to the effects of changes in the refractive index due to changes in the thickness of the ITO film, changes in the coating thickness of the photoresist, etc.

Therefore, the inventor used monochromatic light instead of the conventional white light illumination of a microscope, and as a result of experiments under various conditions, the inventor found that the central wavelength of 380~
In the range of 1200nm, the wavelength width of monochromatic light is 0.1~
Within the range of 250 nm, the ITO film pattern on the glass substrate could be detected with high contrast between light and dark.

According to this method, it was possible to accurately and reliably recognize the pattern of the ITO film without being affected by noise components.

In addition, in this experiment, when the center wavelength of the monochromatic light to be irradiated was 380 nm or less, the illumination wavelength was absorbed by the glass of the photomask village during the positioning of the sample with the microscope, and the amount of light was insufficient. It exposed the photoresist coated on the surface, making it unusable. Also,
At long wavelengths of 1200 nm or more, the lens aberration of the optical microscope has a large effect, causing blurring in the magnified image formed by the microscope, making it unsuitable for pattern recognition. moreover,
When the wavelength width of monochromatic light is 0.1 nm or less, the amount of illumination light decreases extremely, making it unsuitable for practical use. Furthermore
When the wavelength width is 250 nm or more, the average amount of reflected light at the irradiation wavelength decreases, and the contrast between brightness and darkness with respect to the glass substrate decreases, making it unsuitable for practical use.

In addition to the above, there is a problem in that the spectral reflection characteristics of the ITO film on the glass substrate change depending on the combination of the composition of the ITO film, the film thickness value, and the coating thickness of the photoresist.

However, as shown in FIG. 3, a photoresist 3 is coated on an ITO film pattern 2 deposited or sputtered on a transparent glass substrate 1, and a white light lamp 16 is used as a light source for an optical microscope 7.
A specific wavelength and a limited wavelength width are prepared as projection light using a turret plate 34 having a plurality of types of monochromatic light filters 33, and a filter is used to maximize the contrast between the glass substrate 1 and the ITO film pattern 2. was able to choose.

In addition, in FIG. 3, 8 is an objective lens, 11
is a condenser lens, 10 is a half mirror, 9
is a video camera.

Furthermore, as shown in FIG. 4, a monochromator 14 is used as the light source of the optical microscope 7, and by making the center wavelength and wavelength width variable, the glass substrate 1 and the ITO
It was possible to select a point where the contrast with film pattern 2 was maximum.

Next, an embodiment according to the present invention will be described with reference to FIGS. 5A and 5B. FIGS. 5A and 5B are block diagrams showing the configuration of an embodiment of the present invention, in which monochromatic light is used as the light source of the optical microscope. In FIG. 5A, transparent glass with a thickness of 0.7 to 5.0 mm is used as the glass substrate 1, and a film with a thickness of 150 Å to 5000 Å is coated on its surface.
An ITO film pattern 2 is formed. glass substrate 1 and
An ITO film pattern 2 whose entire surface is coated with a photosensitive agent such as a positive or negative photoresist 3 to a thickness of 0.3 μm to 7.0 μm is used as a sample.
4 is a photomask provided on a table on which a sample is placed, and a chrome pattern 5 is provided on the sample side. Reference numeral 6 denotes a lens barrel of an optical microscope 7, in which an objective lens 8 is attached to the sample side and a video camera 9 is attached to the opposite side. Reference numeral 10 denotes a half mirror, which is connected to a monochromatic meter 14 through a light guide 13 at the tube mouth 12 on the condenser lens 11 side.

The monochromatic meter 14 includes a white light lamp 16 that is turned on by a power source 15, and a diffraction grating 20 that is rotated by a motor 19. and,
The reflected light flux of this diffraction grating 20 and the light guide 13
It consists of a slit 21 and a condenser lens 22. Note that 39 is a motor that opens and closes the slit 21.

The video camera 9 is connected to an image processing device 32 via a camera control unit 23. This image processing device 32 converts the output signal of the video camera 9 from analog to digital. A/D
A change 24, a memory 25 that stores this digitally converted signal, a CPU (central processing unit) 26 that controls data etc. in this memory, and this CPU
26 to the drive motor 19 of the diffraction grating 20 via the control bus 31a;
Input/output device 2 from CPU 26 to white lamp power supply 15 of monochromatic meter 14 via control bus 31b
8, and an input/output device 27 that connects the CPU 26 to the X-Y-θ drive motor 29 of the sample placement table via the control bus 31c.

Figure 5B shows the monochromatic meter 14 shown in Figure 5A.
FIG. 2 is a configuration diagram of an interference filter used in place of FIG. In FIG. 5B, reference numeral 34 is a turret plate having a plurality of different monochromatic light filters 33 around the circular periphery, and the projected light of the white light lamp 16 turned on by the power supply 15 is passed through the condenser lens 36, and the monochromatic light The light is introduced into one end of the light guide 13 via the filter 33 and the condenser lens 37, and the other end is connected to the tube opening 12 of the lens barrel of the optical microscope 7.

Next, the operation of this embodiment will be described. First, the case where the monochromator 14 is used as the light source lamp of the optical microscope 7 will be described.

An image of the workpiece is inputted to an image processing device 32 by the microscope 7 via a video camera 9 and a camera control unit 23 paired with this camera. In this image processing device, a digitized image signal passes through an A/D converter 24 and an image memory 25, and is processed by a CPU 26.
The θ drive motor 29 is controlled to perform an automatic positioning function. Inside the image processing device 32, while checking the signal input from the video camera 9,
The drive motor 19 of the diffraction grating 20 of the monochromator 14 is controlled, the wavelength of the illumination light source of the optical microscope 7 is changed, and the wavelength at which image processing is optimal is searched steplessly. Further, the CPU 26 increases the output signal to the power supply 15 via the input/output device 28 and controls the brightness of the white light lamp 16 of the monochromatic meter 14 so that the overall brightness level of the input signal is optimized.

FIG. 5B shows a case where an interference filter is used in place of the monochromator 14 shown in FIG. 5A, and the wavelength of the illumination light source of the microscope is changed by driving the diffraction grating of the monochromator as described above. Instead of the words, "By driving the switching motor 38 of the turret plate 34 to which a plurality of monochromatic light filters 33 are attached, and by switching the monochromatic light filters 33, the illumination wavelength of the microscope is changed, making it ideal for image processing." 6 shows a flowchart in which the image processing device aligns the ITO film pattern with respect to the photomask target mark through the objective lens of the optical microscope. First, the apparatus of this embodiment is started (step 40), and the CPU 26 drives the X-Y-θ placement motor 29 of the sample placement table via the input/output device 30, and the photomask 4 is transferred via the optical microscope 7. The image of the target mark is captured (step 41), and the center of gravity of the image is calculated (step 42). Next, the CPU 26 imports the ITO film pattern 2 target mark (step 43) and
Calculate the center of gravity of the ITO film pattern (step 44),
Target of photomask 4 and ITO film pattern 2
The amount of deviation of the center of gravity coordinates of both the target mark and the target mark is calculated (step 45). Next, the CPU 26 determines whether the alignment of the optical microscope with respect to the ITO film pattern is completed (step 46). If the above alignment has not been completed, the CPU 26 drives the X-Y-θ drive motor of the sample mounting table (step 47) and repeats the above steps again to complete the alignment (step 48).

FIG. 7 is a flowchart in which the image processing device controls the illumination of an optical microscope using a monochromator.
First, start up the device of this embodiment (step 50),
The image processing device 32 captures the image of the ITO film pattern 2 (step 51) and creates a histogram of the image density distribution (step 52). Next, CPU2
6, the drive motor 19 of the diffraction grating 20 is driven and rotated via the input/output device 27 (step 53), and it is determined whether wavelength scanning is completed (step 54). If the wavelength scanning is not completed, the diffraction grating 20 is rotated so that the image density reaches the maximum value (step 55), the image of the ITO film pattern 2 is captured (step 56), and the image density distribution is adjusted. Create a histogram (step 57). If the predetermined average density cannot be obtained, the width of the slit 21 is moved via the motor 39 (step 58), and the illumination intensity is varied so as to maintain the predetermined average density (step 59). If the adjustment of the slit width is not completed, repeat steps 56 to 59, and if it is determined that the adjustment has been completed, the CPU 26
is the calculation of the binarized slice level (step
61) and end (step 62).

(Effects of the Invention) Compared to the laser beam scanning method conventionally used for recognizing ITO film patterns deposited or sputtered on transparent glass substrates, the present invention is not only inexpensive but also optimal. Adjustment time for use has become shorter. Furthermore, the conventional optical microscope method has a small brightness contrast between the transparent ITO film and the transparent glass substrate.
Compared to the previous case where it was impossible to recognize ITO film patterns, the present invention uses a microscope with an optical magnification of 5 times, an aperture of 2/2
Two 3-inch video cameras were used to align the X-Y-θ coordinates of the sample material mounting table, and an ITO film with a thickness of 400 to 700 Å was deposited or sputtered on a transparent glass substrate with a thickness of 1.1 mm. By coating the film pattern with a photoresist film with a thickness of 0.5 to 1.9 μm, the alignment accuracy of the photomask could be set to ±1.0 μm.

Moreover, for workpieces with ITO film patterns as target marks, which was impossible with conventional optical microscope methods, it is now possible to automatically align photomasks with target marks using inexpensive equipment, and it is also possible to achieve high precision. did it.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram of spectral reflectance measured using an optical microscope for a photoresist film coated on a transparent glass substrate. Figure 2 is a photoresist film coated on an ITO film deposited or sputtered on a transparent glass substrate. Fig. 3 is a diagram showing the spectral reflectance characteristics measured using an optical microscope, and Fig. 3 is a schematic diagram of an optical microscope using a white light lamp as a light source and a turret plate equipped with a plurality of monochromatic light filters, as an embodiment of the present invention. 4 is a schematic diagram of an optical microscope using a monochromator instead of the turret plate in FIG. 3; FIG. 5A is a block diagram showing the configuration of an embodiment according to the present invention; FIG. 5B 5A is a block diagram of a monochromatic light filter used in place of the monochromator in FIG. FIG. 7 is a flowchart of lighting control according to an embodiment of the present invention. 1...Glass substrate, 2...ITO film pattern, 3
...Photoresist test film, 4...Photomask,
7... Optical microscope, 9... Video camera, 13...
...Light guide, 14... Monochromatic meter, 16... White light lamp, 18... Slit, 19, 38, 39
... Motor, 20 ... Diffraction grating, 23 ... Camera control unit, 24 ... Analog/digital converter, 25 ... Memory, 26 ... CPU,
29... X-Y-θ drive motor for the sample mounting table, 32... Image processing device, 33... Monochromatic light filter, 34... Turret plate.

Claims (1)

[Claims] 1. An optical microscope in which a transparent conductive film pattern formed on a transparent glass substrate is used as a workpiece to be recognized, the conductive film pattern of this workpiece is coated with a photoresist film, and monochromatic light is used as an illumination system. 1. A method for detecting the position of a transparent conductive film, the method comprising processing a captured image using the method. 2. The method for detecting the position of a transparent conductive film according to claim 1, wherein the monochromatic light has a center wavelength in the range of 380 to 1200 nm and a wavelength width of 0.1 to 250 nm. 3. The method for detecting the position of a transparent conductive film according to claim 1, wherein the monochromatic light has a center wavelength and a wavelength width that are variable in steps. 4. The method for detecting the position of a transparent conductive film according to claim 1, wherein the monochromatic light has a center wavelength and a wavelength width that are continuously variable. 5 A transparent conductive film pattern formed on a transparent glass substrate as a workpiece to be detected, a means for coating the conductive film pattern with a photoresist film, and a monochromatic an optical microscope that uses light as an illumination system; a video camera that is attached to the optical microscope to take an image of the detected workpiece; and an illumination system of the optical microscope that inputs an output signal of the video camera and uses the output signal. A transparent conductive film position detection device comprising an image processing device that performs feedback control of a light source. 6. The position detection device for a transparent conductive film according to claim 5, wherein the monochromatic light is output light from a monochromator. 7. The position detection device for a transparent conductive film according to claim 5, wherein the monochromatic light is output light through a white light interference filter.