JPS6373379A - Image recognizing method for transparent conductive film pattern - Google Patents

Abstract

PURPOSE:To stably recognize a transparent conductive film pattern on a transparent substrate by executing the illumination from the rear surface of the transparent substrate and recognizing an image with the reflecting light of the illumination. CONSTITUTION:An indium tin oxide ITO film pattern 1 to recognize an image for alignment is formed on the surface of a transparent glass substrate 2, and a photoresist 3 having a sensitive hardenability to an ultraviolet exposure for the exposure in a photolithography is uniformly coated from the top of an ITO film. In the lower direction of the pattern 1, an aperture part 4a is provided for the image pick-up by a microscope camera 5. The camera 5 has a half mirror 6 between an objective lens 5a and an eyepiece 5b, and from other illumination light source 7 to the same axis as an observation light axis, the illumination of a visible light is given to an observing surface. Thus, a reflecting light from the observing surface is directly advanced, image-formed to an image pick-up element 8 and converted to an electric signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for image recognition of a transparent conductive film pattern formed on the surface of a transparent substrate.

[Conventional technology]

2. Description of the Related Art Display devices using liquid crystals and electroluminescence (EL) use substrates in which transparent electrodes are formed on the surface of a transparent substrate such as a glass substrate. ITO film (indium tin oxide film) is used as this transparent electrode.
A transparent conductive film patterned by photolithography is used. In the exposure process in this photolithography, so-called register mark alignment (alignment mark comparison) is performed when aligning the original image pattern such as a mask film or glass mask with the glass substrate on which an ITO film is formed and a photoresist is coated. At this time, a method is used in which alignment marks are formed in advance on the surface of the glass substrate using a transparent conductive film, and registration marks are aligned by image recognition of the marks using electrical signals. .

In the conventional image recognition method, as shown in FIG. 3, illumination is applied from the front side of the transparent substrate 2, that is, from above the original image pattern 1), and the reflected light is used. FIG. 4 is a graph showing the contrast of the electrically converted identification image.

Furthermore, other conventional image recognition methods utilize the fact that there is a difference between the ITO film and the surface of the glass substrate, and that this difference does not change even when coated with photoresist. By irradiating it with light), image recognition of the pattern of the IT○ film was performed based on the phase shift of the light caused by this difference.

[Problem that the invention seeks to solve]

However, in the image recognition method using illumination from the surface side of the transparent substrate, the transparent substrate, especially the transparent glass substrate 2, and the transparent conductive film, especially the ITO film 1, have very similar transmission characteristics, reflection characteristics, and refraction characteristics. Because it looks transparent when viewed from the outside, it is difficult to distinguish between the transparent conductive film surface and the transparent glass substrate surface.In addition, the light absorption characteristics of the photoresist 3 coated almost on the entire surface of the substrate and the flatness of the photoresist surface Due to the scattering of reflected light due to the fact that the brightness is not bright, there is noise, such as the difference in brightness between the IT○ film pattern and the glass substrate being about 1 bit when the brightness level is shown in 64 gradations as shown in the graph of Figure 4. There was a problem that image recognition was extremely difficult due to the component level.

Furthermore, although conventional image recognition methods for transparent conductive film patterns that use coherent light improve recognition reliability, they use coherent monochromatic light and require phase shift detection, making the equipment complex and expensive. There have been problems in that there is a problem with this, and that it takes a long time to detect it.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide an image recognition method capable of recognizing a transparent conductive film pattern on a transparent substrate at low cost, at high speed, and stably.

[Means for solving problems]

Means for achieving the above object of the present invention is a method for image recognition of a transparent conductive film pattern formed on the surface of a transparent substrate, in which illumination is performed from the back surface of the transparent substrate and image recognition is performed using reflected light of the illumination. It is something to do.

In the image recognition described above, it is also possible to simultaneously image recognize the document image pattern used for exposure together with the transparent conductive film pattern.

[Effect]

In the present invention, illumination is performed from the back surface of the transparent substrate, and image recognition is performed using the reflected light. Therefore, image recognition can be performed stably without being affected by the photoresist on the front surface. As mentioned above, the transparent substrate and the transparent conductive film have similar reflection characteristics, but without the influence of the photoresist, sufficient image recognition is possible, and identification with the original image pattern depends on the contrast. It's possible because it's big. Therefore,
Ordinary visible light is sufficient as the illumination used, and ordinary image recognition using an image sensor or the like can be performed, so an inexpensive and high-speed image recognition method can be provided.

C Embodiment] An embodiment of the present invention will be described below in detail based on the drawings.

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

An ITO film pattern 1 to be image-recognized for positioning is formed on the surface of a transparent glass substrate 2, and a photoresist 3 having photocurability sensitive to ultraviolet light is applied from above the ITO film for exposure in photolithography. Uniformly coated. The back surface of the glass substrate 2 is fixed to a work surface plate 4 by vacuum suction or the like for exposure. In this work surface plate 4, the above-mentioned positioning I
An opening 4a is provided below the TO film pattern 1 for imaging by a microscope camera 5. The microscope camera 5 has a half mirror 6 between an objective lens 5a and an eyepiece lens 5b, and provides visible light illumination to the observation surface from a side illumination light source 7 coaxially with the observation optical axis (coaxial epi-illumination method). The reflected light from the observation surface travels straight, forms an image on the image sensor 8, and is converted into an electrical signal. After this electric signal is subjected to processing such as amplification in the amplifier 9, it is converted into a digital value (for example, 64 gradations) indicating the brightness level of the image by the A/D converter IO. Above the glass substrate 2 is a glass mask 1) used for exposure, on which a document image pattern is deposited and formed as a chromium film 1)a together with alignment marks.

FIG. 2 is a graph showing the brightness level of the image obtained in the above example. By appropriately adjusting the brightness of the illumination, the brightness level ■ of the reflected light from the glass substrate 2 and the brightness level ■ of the reflected light from the ITO film pattern 1 do not pass through the photoresist 3, so the above digital values can be changed. A contrast of 2 to 3 bits or more can be obtained. Since the level of the noise component is usually kept below 1 bit, I
Image recognition of the TO film pattern 1 becomes fully possible.

Further, the brightness level (1) of the pattern on the glass mask is observed through the glass substrate 2 and the photoresist 3, but since the pattern on the glass mask has a high contrast in the first place, simultaneous recognition is possible without any problem.

The present invention is not limited to the above-mentioned embodiments, but can be applied in various ways and implemented in accordance with the gist of the present invention.

For example, the transparent substrate is not limited to a glass substrate, and may be made of transparent resin, and the transparent conductive film is not limited to an ITO film, but may be made of other materials. Further, the application of the present invention is not limited to so-called registration mark alignment, but can also be applied to product inspection.

〔Effect of the invention〕

As described above, according to the present invention, the light is illuminated from the back side of the transparent substrate without passing through the photoresist, and the image of the transparent conductive film pattern on the surface of the substrate is recognized. , it is possible to avoid the instability of the image formation on the image sensor surface and the decrease in contrast due to interference between the reflected light and direct light from the photoresist, and it is also possible to avoid the need for image recognition using coherent light, which is inexpensive and Image recognition of a transparent conductive film pattern on a transparent substrate can be performed at high speed.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is a graph showing the brightness level of an image obtained in the embodiment, Fig. 3 is an explanatory diagram of a conventional example, and Fig. 4 is an image of a conventional example. It is a graph showing the brightness level of. ■...ITO film pattern (transparent conductive film pattern) 2.
...Glass substrate (transparent substrate) 5...Microscope camera 7...Illumination light source 8...Image sensor 1)...Glass mask (original image pattern) Patent applicant Oak Manufacturing Co., Ltd. Figure 3 Figure 4

Claims (2)

[Claims] (1) A method for image recognition of a transparent conductive film pattern formed on the surface of a transparent substrate, characterized in that illumination is performed from the back side of the transparent substrate, and image recognition is performed by reflected light of the illumination. Pattern image recognition method. (2) The image of the transparent conductive film pattern according to claim 1, wherein the image recognition is performed by simultaneously recognizing the image of the transparent conductive film pattern and a document image pattern used for exposure. Recognition method.