JP2000039599A - Method and device for inspecting liquid crystal display substrate and liquid crystal display substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display visually a size measurement result of an inspection objective pattern in a liquid crystal display substrate such as a TFT(thin film transistor) substrate and a CF(color filter) substrate. SOLUTION: This device is provided with a vertical illumination optical system consisting of a vertical illumination mirror barrel 1 illuminating a liquid crystal display substrate 18 loaded on an XY stage 17 from just above to obtain an optical image on the liquid crystal display substrate 18 and a CCD camera 2 and an optical cut-out optical system consisting of slit projection optical X, Y mirror barrels 3, 4 tilted at 45 deg. on the liquid crystal substrate 18 to illuminat and obtain the optical image on the liquid crystal display substrate 18, observation optical system X, Y mirror barrels 9, 10 and CCD cameras 11, 12 to obtain the optical images of the cut-off part of the liquid crystal display substrate 18 and an oriented film, a seal agent and a conductive pattern for every inspection coordinates on the liquid crystal display substrate 18 by these CCD cameras 2, 11, 12. They are recognized as images by a personal computer 14 to obtain the sizes of these widths and heights, etc., and to make difference values between the obtained sizes and the reference sizes display on a summing up monitor 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for monitoring a manufacturing process of a liquid crystal display substrate, and more particularly to an LCD (Liquid Crystal Display).
In the process of assembling a TFT (Thin Film Transistor) substrate, an STN (Super Twisted Nematic) substrate, and a CF (Color Filter) substrate combined therewith, which are mainly used as a liquid crystal display substrate in a crystal display (liquid crystal display device). The present invention relates to a method and an apparatus for inspecting dimensions of various patterns formed on a liquid crystal display substrate, and to such a liquid crystal display substrate to be measured.

[0002]

2. Description of the Related Art A liquid crystal display device represented by a TFT-LCD provides display quality equivalent to that of a conventional CRT (Cathode Ray Tube) as a display screen of a personal computer or the like, while greatly contributing to space saving of equipment. Therefore, the demand is expanding rapidly. At the same time, with the expansion of its application range, higher performance of devices such as larger screen, higher definition, and lower power consumption is required.Manufacturers have developed products unique to each company, and We are trying to differentiate.

FIG. 14 is an explanatory view schematically showing a manufacturing process of a liquid crystal display device. The manufacturing process of the liquid crystal display device is generally divided into an array process (commonly called a pre-process) and an LCD process (commonly called a post-process), and FIG. 14 particularly shows the LCD process in detail.

In the array process, a TFT substrate in which TFT elements are formed in a matrix on a glass substrate, and R (red), G (green), and B (blue) color filters are formed in a matrix on the glass substrate. The CF substrate and the CF substrate are manufactured in separate manufacturing steps. Then, in the LCD process, these TFTs
The substrate and the CF substrate are opposed to each other, the gap between them is controlled to about several μm, and they are precisely positioned and bonded to each other, and the liquid crystal is sealed and sealed between these substrates. Manufacturing of the liquid crystal display panel is completed in the above steps, and in a subsequent assembling step, a driving IC is mounted on the liquid crystal display panel and connected to and mounted on a device such as a personal computer.

[0005] In the above series of manufacturing steps, particularly in the array step, appearance inspection of thin film patterns manufactured by photolithography (a series of steps of film formation, resist coating, exposure, development, etching, and resist stripping) is performed. A disconnection inspection or a characteristic inspection of TFT elements and the like are all performed for each manufacturing process, and after the inspection is completed, those which are determined to be defective are excluded from the manufacturing process. (Return to the manufacturing process) to prevent defective products from flowing into the subsequent manufacturing process, and to feed back the inspection results to the manufacturing equipment to act to encourage adjustment of process conditions and inspection of the equipment, resulting in stable operation. Production yields.

On the other hand, in the LCD process, the state of each manufacturing process is monitored according to the procedure shown in FIG. 14 similarly to the array process.

That is, first, a TFT substrate or a CF substrate, which is patterned on a large glass substrate (generally, 360 mm × 460 mm or the like) used in the array process by two or four chamfers, is cut into unit sizes. In step 100), the dimensions after the cutting and the presence or absence of cracks or cracks in the cut portions are inspected (step 101).

Next, a polymer film (hereinafter simply referred to as an alignment film) for functioning as a liquid crystal alignment is transferred and baked on a TFT substrate or a CF substrate (Step 102), and the rubbing roller is rotated at a high speed. The alignment film is rubbed by pressing (step 104). As the alignment film, a varnish-like material obtained by dissolving a polyimide-based polymer material in a solvent such as NMP (N-methyl-pyrrolidone) is generally used in many cases. A polymer thin film is formed on a substrate through a process of heating and baking up to about 200 degrees Celsius in a hot plate or a baking furnace. The thickness of the alignment film after firing is about 0.1 μm
It is as follows. Here, after the transfer and firing of the alignment film, the inspection target is the printed dimension of the alignment film on the glass substrate, the presence or absence of pinholes, and the scratches and unevenness of the alignment film after rubbing (steps 103 and 105). .

Next, on the TFT substrate or the CF substrate, a sealing agent (epoxy-based adhesive) for sealing the liquid crystal, and when the TFT substrate and the CF substrate are bonded, conduction between these substrates is ensured. (Step 10)
6, 108). As the conductive paste, a solution is used in which conductive beads obtained by plating a metal sphere such as Ni or Au on a plastic sphere having a diameter of several μm are dispersed in an epoxy adhesive similar to a sealant. The sealant and the conductive paste are applied on a substrate by a microdispenser. Here, the application position and width (application diameter) of the sealant or the conductive paste are inspected, and the sealant is inspected in addition to the presence or absence of interruption (step 10).
7, 109).

Next, spacers are dispersed on a TFT substrate or a CF substrate to keep the gap between the substrates constant when these substrates are bonded (step 11).
0). As the spacer, a method is mainly employed in which a plastic sphere having a diameter of several μm is dispersed in a solvent containing distilled water as a main component, and the dispersion is uniformly dispersed on a substrate by spraying the sphere. Here, the number of spacers dispersed per unit area on the substrate and the presence / absence of the denseness of the spacers are inspected (step 111).

Finally, the TFT substrate and the CF substrate are bonded to face each other (step 112), and it is checked whether the gap between these substrates is uniform (step 113).
A liquid crystal display panel is formed by injecting and sealing liquid crystal between these substrates (step 114), and after lighting inspection (step 115), connection with the device is performed in the next assembly process.

However, in the above LCD process, as compared with the array process, a large number of inspection objects are allowed if a dimensional error such as a cut size of the glass substrate is to a certain extent. , 11
At present, all inspections other than 5) are sampling inspections. Furthermore, since most of the inspection in the LCD process is performed manually by an operator, the inspection requires time, oversight occurs, and there is a problem that the measurement result differs depending on the operator. . In addition, LCD
In the process, there is a problem that the inspection result cannot be fed back to the manufacturing apparatus in a timely manner because the inspection result is difficult to visualize. As a result, the manufacturing yield of the LCD process is lower than that of the array process. , Has always been low. Therefore, by automating the inspection of the LCD process, an effect of greatly improving the production yield of the LCD process is expected.

Under these circumstances, Japanese Patent Application Laid-Open No. 9-9 / 1990
As described in Japanese Patent No. 0384, the liquid crystal sealing sealant formed on the TFT substrate or the CF substrate is automatically inspected for breakage, and when the breakage of the sealant is detected, the substrate is removed from the manufacturing process. A method has been proposed in which the production efficiency of the LCD process is increased by extracting.

[0014]

However, in the prior art proposed above, only the presence / absence of breakage of the sealant formed on the substrate is to be inspected, and the effect is not large in the entire LCD process. The effect is expected to be remarkably small, even if the effect extends to the improvement of the manufacturing yield. In order to improve the manufacturing yield of the entire LCD process, it is essential to develop a system that automates the inspection work in the LCD process as much as possible, visualizes the inspection result, and feeds it back to the manufacturing apparatus in a timely manner. For that purpose, it is necessary to develop a means for reliably detecting various patterns formed on the TFT substrate or the CF substrate with necessary and sufficient dimensional accuracy.

A first object of the present invention is to provide a liquid crystal display substrate having an L
In the CD process, the cutting dimensions of the glass substrate on the liquid crystal display substrate, the printing dimensions of the alignment film, the applied state of the sealant and the applied state of the conductive paste are automatically measured, and the measurement results are visualized and immediately sent to the manufacturing apparatus. It is an object of the present invention to provide a method for inspecting a liquid crystal display substrate, which is capable of feeding back to a user.

A second object of the present invention is to provide a liquid crystal display substrate having an L
In the CD process, the cutting dimensions of the glass substrate on the liquid crystal display substrate, the printing dimensions of the alignment film, the applied state of the sealant and the applied state of the conductive paste are automatically measured, and the measurement results are visualized and immediately sent to the manufacturing apparatus. It is an object of the present invention to provide a liquid crystal display substrate inspection apparatus capable of providing feedback to a liquid crystal display substrate.

A third object of the present invention is to provide a liquid crystal display substrate having an L
An object of the present invention is to provide a liquid crystal display substrate suitable for automatically measuring a print dimension of an alignment film in a CD process.

[0018]

SUMMARY OF THE INVENTION The present invention provides a method for cutting a glass substrate having a common type (namely, for measuring the position and shape of a pattern on a substrate) among inspection items in an LCD process. It is intended for inspection of dimensions, printing dimensions of alignment film, application state of sealant, and application state of conductive paste. In the rubbing state inspection, gap inspection, and lighting inspection of the alignment film, the inspection target is rubbing unevenness and display unevenness. In the inspection of the spacer dispersion state, the size of the spacer to be inspected is as small as several μm. Since it is extremely small compared to the inspection object, it is excluded from the inspection object of the present invention.

In order to achieve the first object, an inspection method according to the present invention converts an automatic measurement result of a dimension of a pattern to be inspected into a difference value from a reference dimension of the pattern to be inspected, and The difference value is sequentially displayed every time.

To achieve the second object, an inspection apparatus according to the present invention comprises an optical system for collecting an optical image of a pattern to be inspected, and means for recognizing the optical image obtained by the optical system. Means for converting an automatic measurement result of the dimension of the pattern to be inspected into a difference value from a reference dimension of the pattern to be inspected, and sequentially displaying the difference value with time for each of the pattern to be inspected; And a means for outputting to the upper information system.

In order to achieve the third object, the liquid crystal display substrate of the present invention has a structure in which a pad for measuring the print dimension of an alignment film is formed on a glass substrate in advance.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing one embodiment of a method and an apparatus for inspecting a liquid crystal display substrate according to the present invention, wherein FIG.
/ 3 inch monochrome CCD camera, 3 is a slit projection optical system X lens barrel, 4 is a slit projection optical system Y lens barrel, 5 and 6 are halogen lamps as an illumination light source, 7 is an optical fiber, 8 is an optical system base, 9 Is an observation optical system X lens barrel, 10 is an observation optical system Y lens barrel, 11 is a 2/3 inch monochrome CCD camera, 12 is a light cutting lens barrel Y CCD camera, 13 is an image input / processing board, 14 is a personal computer, 15 is an image observation monitor, 16
Is a monitor for counting inspection results. FIG. 1B is a diagram showing the structure of the observation optical system in FIG. 1A and the positional relationship with respect to a TFT substrate to be inspected, wherein 1 is an epi-illumination lens barrel, 1a is a 2 × objective lens, 1b is a half mirror, 3a is a collimating lens, 3b is a slit, 3c
Is a 3 × objective lens, 9a is a relay lens, 9b is a 10 × objective lens, 17 is an XY stage, 17a is a reflector, 1
8 is a liquid crystal display substrate, P is a light irradiation center point, and FIG.
Parts corresponding to (a) are given the same reference numerals. Further, FIG. 1C shows the XY stage 17 in FIG.
FIG. 9 is a diagram showing a mounting state of the liquid crystal display substrate 18 above,
Parts corresponding to those in FIG. 1B are denoted by the same reference numerals.

This embodiment uses a TF as a liquid crystal display substrate.
An example is a manufacturing process of a TFT-LCD using a T substrate.
(T substrate 18), TFT substrate or STN substrate to be inspected by the observation optical system, cut part of glass substrate on CF substrate, printed end of liquid crystal alignment film on glass substrate, sealant and conductive paste Are taken, and the dimensions of the inspection object are measured by image processing.

1 (a) and 1 (b), a TFT substrate 18 is mounted on an XY stage 17, and an observation optical system irradiates the TFT substrate 18 with light from directly above, and converts the optical image thereof. One epi-illumination optical system to detect and this TFT
It is configured by combining two pairs of light cutting optical systems that irradiate the substrate 18 with light obliquely and detect the optical image.

The epi-illumination optical system is two-thirds of the epi-illumination lens barrel 1 containing the double objective lens 1a and the half mirror 1b.
Inch monochrome CCD camera (hereinafter referred to as CCD camera)
2 is attached. And FIG.
As shown in (b), the light incident from the halogen lamp 5 via the optical fiber 7 is reflected by the half mirror 1b in a direction directly below (in the direction of arrow Z), and is mounted on the XY stage 17 by the double objective lens 1a. The light is condensed and irradiated on the TFT substrate 18 placed. The center point of this irradiation range is called a light irradiation center point P. The reflected light from the light irradiation area of the TFT substrate 18 is transmitted through the double objective lens 1a and the half mirror 1b to the C light source.
The light is received by the CD camera 2. Thereby, the TFT substrate 1
The light image within the light irradiation area 8 is detected by the CCD camera 2 and supplied to the image input / processing board 13 as an image signal.

Here, the aperture ratio of the objective lens 1a is 0.0
6. The working distance is 92 mm, so that a 3 mm square area on the TFT substrate 18 can be observed by the CCD camera 2. The pixel size on the CCD camera 2 is 7 μm.

On the other hand, the light cutting optical system includes an X light cutting optical system in which light irradiating means and light receiving means are arranged in the X direction, and a Y light in which light irradiating means and light receiving means are similarly arranged in the Y direction. The X and Y light cutting optical systems have the same structure. FIG. 1B shows an X-light cutting optical system, which is one of them, and the light-cutting optical system will be described with reference to FIG.

The X-light cutting optical system includes a collimator lens 3a.
A 2 / 3-inch monochrome CCD camera 11 (hereinafter, referred to as a CCD camera) containing a slit projection optical system X lens barrel 3 containing a 3x objective lens 3c and a slit 3b, and a 10x objective lens 9b and a relay lens 9a. ) Is attached to the observation optical system X lens barrel 9. The slit projection optical system X lens barrel 3 and the observation optical system X lens barrel 9 are
They are arranged on the opposite sides of the optical axis center point P on the TFT substrate 18 in the X direction. The optical axis of the collimating lens 3a housed therein, the slit 3b having a width of 25 μm and the length of 5 mm, and the 3 × objective lens 3c are positioned at the optical axis center point P. And is tilted so as to be at an angle of 45 degrees with respect to the surface of the TFT substrate 18. Similarly, the observation optical system X lens barrel 9 is connected to the 10 × objective lens 9 b housed therein. The optical axis with the relay lens 9a passes through the optical axis center point P, and T
The FT substrate 18 is inclined at an angle of 45 degrees with respect to the surface of the FT substrate 18. The slit projection optical system X lens barrel 3 and the observation optical system X are fixed so that such an arrangement relation is fixed between the epi-illumination optical system and the epi-illumination lens barrel 1.
A lens barrel 9 is attached to the optical system base 8 together with the epi-illumination lens barrel 1.

In such a configuration, in the slit projection optical system X lens barrel 3, light incident from the halogen lamp 6 via the optical fiber 7 is collimated by the collimating lens 3a, and a part thereof is extracted by the slit 3b. Through the 3 × objective lens 3c, the light is irradiated to a range determined by the slit 3b centered on the optical axis center point P on the TFT substrate 18. Light reflected from this range (hereinafter referred to as slit light) enters the observation optical system X lens barrel 9 and is received by the CCD camera 11 via the 10 × objective lens 9b and the relay lens 9a. As a result, a light image of the slit light reflected by the TFT substrate 18 is detected by the CCD camera 11 and supplied to the image input / processing board 13 as an image signal.

Here, the aperture ratio of the 3 × objective lens 3c is 0.07, the working distance is 72.5 mm, and the projection of the slit 3b on the TFT substrate 18 is 12 μm wide and 1.times. Long.
Reduce to 7 mm dimensions. The observation optical system X lens barrel 9 is TF
The total reflection light from the projection area of the slit 3b reduced and projected on the T substrate 18 is observed by the CCD camera 11. CCD
The camera 11 can observe a range of 1.5 mm in the length of 1.7 mm of the reduced projection area of the slit 3 b on the TFT substrate 18. The aperture ratio of the objective lens 9b is 0.28, the working distance is 33.5 mm, and the pixel size on the CCD camera 11 is 2.5 μm.

As for the Y light cutting optical systems, the slit projection optical system Y lens barrel 4 and the observation optical system Y lens barrel 1
0 is the same as the X light cutting optical system except that it is disposed on the opposite side in the Y direction orthogonal to the X direction across the optical axis center point P, and is fixed by the optical system base 216. One pair forms a light cutting optical system.

Here, in order to simplify the following description,
The slit projection optical system X lens barrel 3 and the observation optical system X lens barrel 9 are simply called a light cutting lens barrel X, and the slit projection optical system Y lens barrel 4
And the observation optical system Y lens barrel 10 are simply referred to as a light cutting lens barrel Y.

The TFT substrate 18 is mounted and fixed on an XY stage 17, and the XY stage 17 moves in the XY directions, thereby positioning the TFT substrate 18. The XY stage 17 has a mounted TF
A reflector 17a for reflecting illumination light from the epi-illumination lens barrel 1 over the entire outer periphery of the T substrate is provided. This reflector 17a is a specular reflector made by buffing the surface of a metal such as aluminum or stainless steel to a mirror surface,
Alternatively, it is a strip-shaped reflector which has been subjected to a surface treatment (for example, white alumite treatment) on the metal to be a scattering reflector, and is 10 mm to 15 mm from the mounting surface of the TFT substrate 18.
mm. With this configuration, an optical image suitable for image recognition of a cut portion of the TFT substrate 18 can be obtained.

The observation optical system having the above configuration is fixed to a Z stage (not shown), and the Z stage moves up and down so that the observation optical system can be focused. . For this focusing, an optical image obtained by the CCD camera 11 of the light-cutting barrel X or the CCD camera 12 of the light-cutting barrel Y is used.

That is, the image forming position Px or Py of the slit light on the image forming plane of the CCD camera 11 or 12 of the light cutting lens barrel at the position where the incident illumination lens barrel 1 is focused.
(For the CCD camera 12) is stored in the memory of the personal computer 14 in advance, and the image forming position Px or Py stored with the image forming position Px or Py of the slit light that changes due to the variation in the height of the surface of the TFT substrate 18 is stored. Is obtained from the number of pixels on the image plane of the CCD camera, and the amount of change in the height of the surface of the TFT substrate 18 can be calculated from the difference (number of pixels) × pixel size ÷ √2. PC 1
In step 4, the optimum height of the Z stage is determined by calculating the amount of change each time the observation position on the TFT substrate 18 changes.

The operations of the XY stage 17 and the Z stage (not shown) are controlled by the personal computer 14 via a controller (not shown). The light quantity of the halogen lamps 5 and 6 is controlled by setting a voltage via a D / A board in the personal computer 14. Further, the personal computer 14 is connected to an information network in the manufacturing site, and can output inspection results to a higher-level information system.

Next, a procedure for inspecting a liquid crystal display substrate will be described using a TFT substrate as an example. First, an operator inputs inspection coordinates (coordinates for taking an image) on the liquid crystal display substrate and reference dimensions (design values) corresponding to the inspection coordinates from input means (not shown) for each type of TFT substrate. Input and register in personal computer 14.

FIG. 2 is a diagram showing input information when measuring the substrate cutting dimension of the TFT substrate 18. Here, 360 mm × 460 mm × 0.7 used in the array process is shown.
230 mm × 460 mm
The size of the glass substrate after the division into the size of mm is inspected.

On the TFT substrate 18, alignment marks M 1 and M 2 are formed in an array process, including an effective display area 18 a (for example, a display screen of 12.1 inch size) on the TFT substrate 18 and an LCD process. All of the patterns formed by are expressed using the alignment mark M1 as a reference position. The operator inputs / registers eight coordinates C1 to C8 as inspection coordinates and reference dimensions (cutting dimensions) corresponding to the inspection coordinates C1 to C8 in the personal computer 14. For example, the reference dimension at the inspection coordinates C1 and C2 is-
X1, the reference dimension at inspection coordinates C3, C4 is Y2, the reference dimension at inspection coordinates C5, C6 is X2, inspection coordinate C
The reference dimension at 7, C8 is -Y1.

FIG. 3 shows a liquid crystal alignment film 1 on the TFT substrate 18.
9 is a diagram illustrating input information when measuring a print dimension of No. 9; FIG.
Here, a state in which the alignment film 19 is formed in the effective display area 18a on the TFT substrate 18 is shown.

The alignment film 19 is formed by dissolving an organic polymer material such as polyimide in a solvent such as NMP (N-methyl-pyrrolidone) to form a varnish. After being transferred to the effective display area 18a, a maximum of 200 degrees Celsius is
This is a polymer thin film formed through a process of heating and firing to a degree of about 0.1 μm, and has a thickness of about 0.1 μm after firing, and is formed so as to cover the effective display area 18a.

The operator uses eight coordinates C9 as inspection coordinates.
To C16 and reference dimensions (alignment film print dimensions) corresponding to the inspection coordinates C9 to C16 are input to the personal computer 14 and registered. Here, for example, the reference dimension at inspection coordinates C9 and C10 is X3, the reference dimension at inspection coordinates C11 and C12 is Y4, the reference dimension at inspection coordinates C13 and C14 is X4, and the reference dimension at inspection coordinates C15 and C16 is Y.
3.

FIG. 4 shows a sealant 20 on the TFT substrate 18.
FIG. 8 is a diagram showing input information when measuring the application state of the application. Here, the alignment film 19 and the sealant 20 are formed on the TFT substrate 18.
Shows a state in which is formed.

An epoxy-based adhesive having a viscosity of about 10 Pa · s is made of TF using a micro-dispenser.
It is applied on the T-substrate 18 with a single stroke from the start point SP to the end point EP, and has a shape between the start point SP and the end point EP as an opening for liquid crystal injection. The application position, application width and application height of the sealant 20 are measured.

For this reason, the operator determines eight coordinates C17 to C24 as inspection coordinates and these inspection coordinates C17 to C24.
The reference dimensions (application position, application width, application height) corresponding to are input to the personal computer 14 and registered. For example, inspection coordinates C
The application position at 17, C18 is -X5, inspection coordinates C1
9 and C20, the application position is Y6, the inspection coordinates C21,
The application position in C22 is X6, the inspection coordinates C23, C2
The application position in No. 4 is -Y5. Further, the application width at the inspection coordinates C17 to C24 is set to, for example, 300 μm, and the application height is set to, for example, 10 μm.

FIG. 5 is a diagram showing input information when measuring the application state of the conductive paste on the TFT substrate 18. Here, the alignment film 19 and the sealant 20 are formed on the TFT substrate 18.
And a state in which conductive pastes 21a to 21c are formed.

These conductive pastes 21a to 21c are made of T
When bonding the FT substrate 18 and the CF substrate, the conductive beads are used to secure conduction between the substrates, and are formed by plating a metal sphere such as Ni or Au on a plastic sphere having a diameter of several μm. Is dispersed in an epoxy adhesive similar to the sealant 20, and this is applied using a microdispenser.

For the sealant 20, the application position and the application diameter are measured. In the case of measuring the conductive pastes 21a to 21c, the reference dimensions (coordinates) of the application position match the inspection coordinates. For this reason, the operator inputs the reference dimensions (application position, application diameter) of the coordinates (hereinafter referred to as coordinates 21a, 21b, 21c) of the application positions of the three conductive pastes 21a to 21c as inspection coordinates to the personal computer 14. And register. For example, the application position at the inspection coordinates 21a is
(X7, Y7), the application position at the inspection coordinates 21b is (X7, Y7).
7, Y8), the application position at the inspection coordinates 21c is (X8,
Y7). Further, the application diameter at the inspection coordinates 21a to 21c is set to, for example, 300 μm.

Although the above description has been made with reference to the TFT substrate 18, the setting is performed in the same procedure for a CF substrate.

According to the procedure described above, the operator sets the inspection coordinates and the reference dimensions corresponding to the inspection coordinates for each type of the TFT substrate and the CF substrate to be inspected. In addition, the inspection coordinates can be set up to a maximum of 100 points for each measurement object, and can be appropriately increased or decreased according to the judgment of the operator.

The operator extracts the TFT substrate and the CF substrate one by one from the manufacturing process, for example, once an hour, and mounts them on the XY stage 17 in FIG. Then, the serial number read from the substrate and the item to be inspected (cutting dimensions of the glass substrate, printing dimensions of the alignment film on the glass substrate, application state of the sealant on the glass substrate, conductive paste on the glass substrate) Of the application state can be selected or a plurality of application states can be selected) to the personal computer 14, and thereafter, the start of the inspection is instructed. The serial number of a board is defined as a unique value of the board.

Next, the TFT substrate and the C
The XY stage 17 is distinguished from the F substrate and the type is determined. After the TFT substrate or the CF substrate is aligned, the inspection coordinates registered in advance for each type coincide with the light irradiation center point P of the observation optical system. Are sequentially moved (for example, in the case of measurement of the substrate cutting dimension, in FIG. 2, the inspection coordinates are in the order of C1 → C2 →... → C8).

Then, an optical image of the inspection object is collected at each inspection coordinate, and its dimensions are sequentially measured by image recognition. Specifically, based on the image recognition coordinates of each measurement target on the sampled image and the coordinates of the linear scale built in the XY stage 17, the coordinates of the measurement target on the TFT substrate 18 (from the alignment mark M1). Distance). It is assumed that the light amount of the halogen lamps 5 and 6 at the time of capturing an image is optimized in advance for each measurement object, and the light amount is controlled from the personal computer 14 for each measurement object. After the inspection, the TFT substrate and the CF substrate are returned to the manufacturing process again by the operator.

Alternatively, for example, at the stage where the cutting process of a glass substrate of a liquid crystal display substrate such as a TFT substrate, an STN substrate, or a CF substrate is completed, the glass substrate is automatically extracted by a transfer device, and the glass substrate is transferred (not shown). The apparatus is mounted on the XY stage 17 and the manufacturing number reading unit (not shown) reads the manufacturing number on the glass plate, and then starts measuring the cut dimensions of the glass substrate. The glass substrate after the inspection is returned to the next manufacturing process (alignment film printing / firing process) by a transfer device and a transport device (not shown).

As described above, every time one manufacturing process is completed, the inspection can be performed fully automatically without the intervention of an operator.

Next, a method of recognizing an image of each dimension measuring object will be described.

FIG. 6A shows the TFT substrate 18 shown in FIG.
Image taken by the CCD camera 2 in a range centered on the inspection coordinate C1 of the above (hereinafter, referred to as an epi-illumination observation image)
FIG. Here, the expression is 256 gradations. In the step of cutting the glass substrate of the TFT substrate 18, the edge portion is chamfered after the glass is cut, and as shown by hatching in FIG. 6A, the chamfered portion is observed with a low luminance.

FIG. 6B is a diagram showing the luminance along a dividing line AA 'orthogonal to the cut portion in FIG. 6A.

In FIG. 6B, this dividing line AA '
Is the intersection of (a) with the preset threshold LS1.
(A) ′. Of these, the coordinates of the intersection (A) outside the TFT substrate 18 can be determined and used as the cutting position of the glass substrate at the inspection coordinates C1. Then, the coordinates (A) are converted into coordinates based on the alignment mark M1 on the TFT substrate 18 and stored in the memory of the personal computer 14.

When the reflector 17a is disposed on the XY stage 17 when recognizing the image of the cutting position of the glass substrate, the brightness of the chamfered portion is low as shown in FIGS. 6 (a) and 6 (b). An image suitable for image recognition can be obtained. This is because the illumination light of the epi-illumination column 1 (FIG. 1) is reflected by the reflector 17a.
6A, and the reflected light is taken into the 2 × objective lens 1a, so that in FIG. 6A, the brightness in the region where the TFT substrate 18 does not exist can be increased. When the reflector 17a is not provided on the XY stage 17, the luminance along the dividing line AA 'in FIG.
As shown in FIG. 6C, the outside of the TFT substrate 18 has a low reflectance, and it is impossible to recognize the cutting position of the glass substrate as shown in FIG.

FIG. 7A shows the TFT substrate 18 shown in FIG.
Pads 22a to 22 for recognizing the print position of the alignment film 19 are formed thereon.
It is a figure showing signs that h was arranged.

Since the alignment film 19 is a very thin transparent film (polyimide thin film) having a thickness of 0.1 μm, it is extremely difficult to recognize the printed end portion of the TFT substrate 18 where the wiring pattern exists. Becomes Therefore, as shown in FIG. 7A, in the arraying process of the TFT substrate 18 (at least before printing the alignment film 19), for example, the wiring pattern on the TFT substrate 18 is not interfered with the wiring pattern. The inspection pads 22a to 22h are formed in advance in the same layer as above, and the dimension measurement after printing and firing of the alignment film 19 in the LCD process is performed on the inspection pads.

As shown in FIG. 7B, the inspection pads 22a to 22h are in the form of, for example, an equilateral triangle having a side of 9 mm.
It is arranged in an area surrounding the observation area IA (here, 3 mm square) of FIG. 1 and taking into consideration the printing position accuracy of the alignment film 19. Therefore, parameters (inspection coordinates C9 to C16 on the substrate 18) input by the operator to the personal computer 14 in advance before the inspection of the printing position of the alignment film 19 are considered in consideration of the positions of the inspection pads 22a to 22h. Must be specified.

The inspection pads 22a to 22h include:
A metal material such as Cr, Al, Ni, Mo, W, or a light-shielding organic material can be used. Note that the inspection pads 22a to 22h can be arranged on the wiring pattern on the TFT substrate 18 with an interlayer insulating film interposed therebetween, whereby the number of inspection pads (the number of measurement points) can be increased. is there.

FIG. 8A shows the TFT substrate 18 shown in FIG.
It is a figure which shows the epi-illumination observation image by the CCD camera 2 in the upper inspection coordinate C9. Here, the expression is 256 gradations.

Since a special roller is used for printing the alignment film 19, the side 19a of the alignment film 19 transferred onto the TFT substrate 18 does not have a linear pattern, but has a characteristic pattern (undulation). ) Occurs. With respect to the epi-illumination observation image shown in FIG. 8A, the luminance was observed at three dividing lines BB ′, CC ′, and DD ′ parallel to the printing side portion 19a of the alignment film 19. 8 (b), (c), respectively.
The result shown in (d) was obtained.

As a result, the printed end portion 19a of the alignment film 19 is formed.
It was confirmed that the characteristic of the undulation pattern on the side 19a of the alignment film 19 was reflected only on the luminance along the dividing line CC ′ near the undulation pattern. That is, paying attention to the amplitude of the luminance change along the direction parallel to the printing side portion 19a of the alignment film 19 in the incident illumination observation image, the dividing line at which the luminance amplitude becomes the maximum (in FIG. 8A, the dividing line C- C ′) to the inspection coordinates C9
At the printing position of the alignment film 19. Then, the position of the dividing line CC ′ on the epi-illumination observation image is referred to as TF
The coordinates are converted into coordinates based on the alignment mark M1 (FIG. 3) on the T substrate 18 and stored in the memory of the personal computer 14.

FIG. 9A shows the TFT substrate 18 shown in FIG.
It is a figure which shows the epi-illumination observation image which has the reference | standard coordinate C17 by the CCD camera 2 (FIG. 1) in the upper inspection coordinate C17, and also represents 256 gradations here. In such an epi-illumination observation image, the sealant 20 formed on the TFT substrate 18 is observed darker than the background, as shown in FIG.

FIG. 9B is a diagram showing a luminance level along a dividing line EE ′ (a direction orthogonal to the application direction of the sealant 20) passing through the center of the visual field in FIG. 9A.

In FIG. 9B, this dividing line EE '
There are two intersections between the luminance level at (a) and the preset threshold value LS2 at (a) and (c), and the distance between them (= pixel number × pixel size) is determined by the sealant 19 at the inspection coordinates C17.
Of the coating width. The middle point (d) between these intersections (a) and (c) is defined as the application position of the sealant 19. These are stored in the memory of the personal computer 14. The midpoint (d) is converted into coordinates based on the alignment mark M1 on the TFT substrate 18 and stored in the memory of the personal computer 14.

The inspection of the sealant 20 covers not only the application width and application position but also the application height. This is because, when the sealant 20 is excessively applied, cracks may occur in the glass substrates when the TFT substrate and the CF substrate are bonded to each other, which may reduce the reliability of products.

FIG. 10A shows the TFT substrate 1 shown in FIG.
8 is a diagram showing an image (hereinafter, referred to as a light-section image) of the light-section lens barrel Y taken by the CCD camera 12 (FIG. 1) with the inspection coordinate C17 on the center of view as the center of the visual field.

Here, the description will be made assuming that the application height of the portion of the sealant 20 printed on the TFT substrate 18 extending in the Y-axis direction is inspected. In this case, a Y light cutting optical system, that is, a light cutting optical system including a slit projection optical system Y lens barrel 4, an observation optical system Y lens barrel 10, and a CCD camera 12 is used.

In FIG. 10A, the CCD camera 12
, A linear slit light SL from the slit projection optical system Y-barrel 4 (FIG. 1) is projected across the X-axis direction. The slit light SL is applied to the surface of the TFT substrate 18 at an inclination angle of 45 ° and is incident on the CCD camera 12 at an inclination angle of 45 °. It is in a state. The top of the curved portion represents the top of the applied sealant, and the straight portion represents the surface of the TFT substrate 18. Therefore, the distance in the Y-axis direction between the linear portion of the slit light SL and the top of the curved portion is √2 times the application height of the sealant 20.

Here, the surface of the TFT substrate 18 and the top of the sealant 20 are determined based on the number (frequency) of the pixels irradiated with the slit light SL for each coordinate of the Y-axis pixel unit. Now, in the field of view 23 of the CCD camera 12, when the frequency is obtained for each coordinate of the Y axis, as shown in FIG. 10B, the loss is the highest in the coordinates where the linear portion of the slit light SL passes, This coordinate is (e). The center of the visual field 23 (inspection coordinates C17) is set substantially at the center of the application width of the sealant 20.
In the maximum height detection range having a width substantially equal to the application width of 0 (the value of this range is set in advance as a parameter), the frequency is similarly obtained for each coordinate of the Y axis. In this case, the vicinity of the top of the applied sealant 20 is substantially flat, and therefore, the frequency becomes maximum in a portion corresponding to the top in the irradiated portion of the slit light SL. FIG. 10B shows the coordinates at this time as (f).

Then, the personal computer 14 (FIG. 1) calculates the distances (= number of pixels × pixel size) between the coordinates (E) and (F) as described above,
Is stored in the memory as the application height.

The above is the inspection of the coating height of the portion of the sealant 20 applied to the liquid crystal display substrate 18 extending in the Y-axis direction. The same inspection processing may be performed using a system, that is, an X-light cutting optical system including the slit projection optical system X lens barrel 3, the observation optical system X lens barrel 9, and the CCD camera 11.

It should be noted that the presence or absence of breakage of the sealant 20 can be inspected by appropriately increasing the inspection coordinates in consideration of the characteristics of the application process using the microdispenser. Here, at the time of focusing of the observation optical system when the sealant is present in the field of view of the light-cutting lens barrel, FIG.
In (b), it is obvious that the displacement of the surface of the TFT substrate 18 can be grasped by judging the coordinate (e) as the image forming position of the slit light SL on the image forming plane of the CCD camera 12.

FIG. 11A shows the TFT substrate 1 shown in FIG.
Inspection coordinates C25 on which conductive paste 21a on 8 is applied
FIG. 3 is a diagram showing an incident illumination observation image by the CCD camera 2 (FIG. 1) in FIG.

The conductive paste 21a formed on the TFT substrate 18 is observed dark against the background. FIG.
The epi-illumination observation image obtained as shown in (a) is binarized by a preset binarization threshold, and is labeled as an inverted image. Further, the area of each labeling region is obtained, and attention is paid only to the labeling regions in a specific area value range (determined from design information).

That is, as shown in FIG. 11B, the barycentric coordinate Q of the labeling area 24 of the conductive paste 21a of interest is calculated, and this barycentric coordinate Q is used as the coating position of the conductive paste 21a at the inspection coordinates C25. Can be. The diameter of the circumscribed circle 25 of the labeling region 24 of interest is defined as the diameter of the conductive paste 21a.

Then, the barycentric coordinates Q on the epi-illumination observation image are converted into coordinates based on the alignment mark M1 (FIG. 5) on the TFT substrate 18 and stored in the memory of the personal computer 14 as the application position of the conductive paste 21a. . The diameter of the circumscribed circle 25 is stored in the memory of the personal computer 14 as the diameter of the conductive paste 21a.

According to the method described above, the TFT substrate 18
Inspection of the substrate cutting dimension, the printing dimension of the alignment film 19 formed on the TFT substrate 18, the applied state of the sealant 20, and the applied state of the conductive paste 21 can be performed.

In the above description, the substrate to be inspected is
The TFT substrate has been described as an example.
For a substrate, STN substrate for STN-LCD, and CF substrate, the dimensions of various patterns can be measured in the same manner.

All the above measurement results are shown in FIG.
13 and a graph as shown in FIG. 13 on the tallying monitor 16 (FIG. 1 (a)).

In the list shown in FIG. 12, the TFT substrate 18
The measurement result is stored as a coordinate value based on the alignment mark M1 in the sheet for each product type in the serial number unit. About the TFT substrate after the glass substrate cutting process,
When the measurement of the substrate cutting dimension is performed, the measurement result is displayed only in the column indicated by (g), and the TFT substrate is again supplied to the next manufacturing process (alignment film printing / firing process). Then, after the completion of the alignment film printing / firing step on the same substrate, the printing dimension of the alignment film 19 is measured as described above, and the result is displayed in a column indicated by (h). Hereinafter, the dimension measurement is repeated by the same method for each manufacturing process.

Alternatively, it is also possible to collectively measure all the objects to be measured at once on the TFT substrate that has been completed up to the conductive paste application step or the spacer dispersion step.

The measurement data stored in the list shown in FIG. 12 is compared with its reference dimension (standard value). If the measured data is out of the range of the standard value, it is stored. Display measurement data in red. Further, when the measurement result is out of the range of the standard value or when the measurement becomes impossible for some reason, the operator instructs the personal computer 14 from input means (not shown) at the discretion of the operator, and only the portion of The dimension measurement operation can be performed again.

FIG. 13 is a diagram showing a result of displaying the list shown in FIG. 12 in a graph. In the figure, a numerical value obtained by subtracting a reference dimension from a measurement result is plotted, and a change with time of each measurement result can be monitored by classifying the measurement results by inspection target items. In this way, it is possible to visualize the fluctuation and the cycle thereof generated in each manufacturing process, and to predict abnormalities in the manufacturing process at an early stage. It is also possible to optimize the maintenance cycle of the manufacturing apparatus.

When the final measurement result is out of the range of the standard value, a warning is output from the personal computer 14 to the upper information system to suspend the operation of the corresponding manufacturing apparatus, and to adjust the manufacturing apparatus. Perform maintenance.

When the dimensions of the TFT substrate and the CF substrate were measured by the method described above, it was found that all the measurements were completed in 5 minutes. However, the inspection coordinates (the number of measurement points) are 6 points for the substrate cutting dimension, 8 points for the printing dimension of the alignment film 19, 8 points for the application position, application width and application height of the sealant 20, and the application position for the conductive paste 20. And the application diameter is 1
Two points. By applying the present invention, the inspection time can be significantly reduced as compared with the manual measurement by the operator, and the inspection frequency and the reliability of the inspection have been improved.

[0092]

As described above, according to the present invention,
In the dimension inspection of a pattern in an LCD process of a liquid crystal display substrate such as a TFT substrate, a CF substrate, and an STN substrate, variation and oversight of measurement results by an operator can be prevented, and inspection accuracy and reliability are greatly improved.

According to the present invention, the L of the liquid crystal display substrate
The time required for pattern dimension inspection in the CD process can be greatly reduced, and the inspection frequency is greatly improved.

Further, according to the present invention, it is possible to visualize the result of the pattern dimension inspection in the LCD step of the liquid crystal display substrate, to predict the abnormality of the manufacturing process at an early stage,
Inspection results can be immediately fed back to the manufacturing process.

Furthermore, according to the present invention, by providing a pad for recognizing the printing position of the alignment film on the liquid crystal display substrate, it is possible to reliably inspect the printing position of the alignment film on the liquid crystal display substrate. Becomes

As described above, the production yield of the liquid crystal display substrate is improved, the production cost of the liquid crystal display substrate is reduced, and further, the effect of reducing industrial waste is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a method and an apparatus for inspecting a liquid crystal display substrate according to the present invention.

FIG. 2 is a diagram showing input information when measuring a cutting dimension of a glass substrate of the liquid crystal display substrate in the embodiment shown in FIG.

FIG. 3 is a view showing input information when measuring a print dimension of an alignment film on a liquid crystal display substrate in the embodiment shown in FIG. 1;

FIG. 4 is a diagram showing input information when measuring the application state of a sealant on a liquid crystal display substrate in the embodiment shown in FIG. 1;

FIG. 5 is a diagram showing input information when measuring the application state of the conductive paste on the liquid crystal display substrate in the embodiment shown in FIG. 1;

FIG. 6 is a diagram showing an image recognition method of a cutting position of a glass substrate of the liquid crystal display substrate in the embodiment shown in FIG.

FIG. 7 is a view showing a liquid crystal display substrate on which pads for recognizing a print position of an alignment film on the liquid crystal display substrate in the embodiment shown in FIG. 1 are arranged.

8 is a diagram illustrating a method for recognizing an image of a printing position of an alignment film on a liquid crystal display substrate in the embodiment shown in FIG.

FIG. 9 is a diagram illustrating an image recognition method in a state where a sealant is applied on a liquid crystal display substrate in the embodiment shown in FIG. 1;

10 is a diagram illustrating a method of recognizing the application height of the sealant on the liquid crystal display substrate in the embodiment shown in FIG.

FIG. 11 is a diagram showing an image recognition method of a conductive paste applied state on a liquid crystal display substrate in the embodiment shown in FIG. 1;

12 is a diagram showing a list of dimension measurement results displayed on the measurement result display monitor in FIG. 1;

FIG. 13 is a diagram showing a graph of a dimension measurement result displayed on the measurement result display monitor in FIG. 1;

FIG. 14 is an explanatory view schematically showing a manufacturing process of the liquid crystal display device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Epi-illumination lens barrel 1a 2x objective lens 1b Half mirror 2 CCD camera 3 Slit projection optical system X lens barrel 3a Collimating lens 3b Slit 3c 3x objective lens 4 Slit projection optical system Y lens barrel 5, 6 Illumination light source 7 Optical fiber Reference Signs List 9 Observation optical system X lens barrel 9a Relay lens 9b 10 × objective lens 10 Observation optical system Y lens barrel 11, 12 CCD camera 13 Image input / processing board 14 Personal computer 15 Image observation monitor 16 Inspection result aggregation monitor 17 XY stage 17a Reflector 18 Liquid crystal display substrate 18a Effective display area 19 Alignment film 20 Sealant 21a-21c Conductive paste 22a-22h Pad for recognizing printing position of alignment film C1-C25 Inspection coordinates M1, M2 Alignment mark

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Eiji Sasaki 3300 Hayano Mobara City, Chiba Prefecture Inside Hitachi, Ltd.Electronic Device Division (72) Inventor Susumu Niwa 3300 Hayano Mobara City, Chiba Prefecture Hitachi, Ltd.Electronic Device Business Internal F-term (Reference) 2F065 AA03 AA21 AA24 AA61 BB02 CC00 CC21 FF01 FF04 GG02 HH04 HH05 JJ03 JJ05 JJ08 JJ26 LL03 LL04 LL28 MM03 PP12 QQ13 QQ31 RR08 2G086 EE10 2H0FA01 A03 FA03 FA03FA03 FA03

Claims (9)

[Claims] In a manufacturing process of a liquid crystal display substrate such as a TFT substrate, a CF substrate, and an STN substrate, a dimension measurement result of an inspection target pattern on the liquid crystal display substrate is converted into a difference value from a reference dimension of the inspection target pattern. A method for inspecting a liquid crystal display substrate, wherein the difference value is sequentially displayed with time for each of the inspection target patterns. 2. The method for inspecting a liquid crystal display substrate according to claim 1, wherein the dimensions to be measured of the pattern to be inspected are a cutting dimension of a glass substrate in the liquid crystal display substrate, and an alignment film on the glass substrate. At least one of a printing size of a sealant, a coating position, a coating width, and a coating height of a sealant on the glass substrate, and a conductive paste coating position and a coating diameter on the glass substrate. A method for inspecting a liquid crystal display substrate, wherein the optical image is measured by image recognition. 3. An optical system for collecting an optical image of a pattern to be inspected formed on the liquid crystal display substrate in a manufacturing process of a liquid crystal display substrate such as a TFT substrate, a CF substrate, and an STN substrate; Means for recognizing the optical image collected in step (a), and measuring the dimension of the pattern to be inspected, which is image-recognized from the optical image, converting the measurement result into a difference value from the reference dimension of the pattern to be inspected, Means for sequentially displaying the difference value over time for each target pattern. 4. An optical system for collecting an optical image of a pattern to be inspected formed on a liquid crystal display substrate in a manufacturing process of a liquid crystal display substrate such as a TFT substrate, a CF substrate, and an STN substrate; Means for image-recognizing the optical image collected in step (a), and measuring the dimension of the inspection target pattern image-recognized from the optical image, converting the measurement result into a difference value from the reference dimension of the inspection target pattern, An inspection apparatus for a liquid crystal display substrate, comprising: means for sequentially displaying the difference value over time for each target pattern; and means for outputting the measurement result to a higher-level information system. 5. The inspection apparatus for a liquid crystal display substrate according to claim 3, wherein the dimensions to be measured of the pattern to be inspected are a cutting dimension of a glass substrate of the liquid crystal display substrate, and an alignment film on the glass substrate. At least one of a printing size, a coating position, a coating width, and a coating height of the sealant on the glass substrate, and a coating position and a coating diameter of the conductive paste on the glass substrate. Inspection equipment for liquid crystal display substrates. 6. A liquid crystal display substrate comprising a glass substrate on which an organic polymer thin film as a liquid crystal alignment film is printed, wherein at least a part of a printed end of the organic polymer thin film is measured for a position of the printed end. A liquid crystal display substrate provided with an opaque film made of a metal material or an organic material for the purpose. 7. The liquid crystal display substrate according to claim 6, wherein the opaque film is disposed on the glass substrate before printing the organic polymer thin film. 8. The liquid crystal display substrate according to claim 6, wherein the opaque film is provided in the same layer as a wiring pattern. 9. The liquid crystal display substrate according to claim 6, wherein the opaque film is provided on an insulating film on a wiring pattern.