JP3252451B2 - Thin film transistor liquid crystal substrate inspection method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method and apparatus for detecting defects in a pattern to be inspected, and more particularly, to a method and apparatus for inspecting a thin film transistor liquid crystal substrate used in a liquid crystal display device as a pattern to be inspected. It concerns the device.

[0002]

2. Description of the Related Art FIG. 1 shows an example of an electric wiring configuration of a thin film transistor active matrix substrate (hereinafter, simply referred to as a thin film transistor liquid crystal substrate) in a case of a 5 × 5 pixel array. As can be seen from the above, the thin film transistor liquid crystal substrate has scanning lines 11 to 15, signal lines 21 to 25, and a thin film transistor 7 and a transparent pixel electrode 8 formed on a glass substrate at the intersection of the signal lines and the scanning lines. However, the liquid crystal display device is basically configured such that the thin film transistor liquid crystal substrate and the common electrode substrate face each other in parallel, and liquid crystal is sealed between the two substrates. In the figure, reference numerals 11p to 15p denote electrode terminal pads corresponding to the scanning lines 11 to 15, and 21p.
p to 25p indicate electrode terminal pads corresponding to the signal lines 21 to 25.

In the thin film transistor liquid crystal substrate having the above structure, if a short-circuit defect 3 occurs between the scanning line 13 and the signal line 23, for example, a display defect along the scanning line 13 and the signal line 23 may occur. It occurs linearly. As shown in FIG. 2A, the short-circuit defect 3a occurs at the intersection of the scanning line and the signal line, and the short-circuit defect 3b occurs in the thin film transistor 7.
However, as a countermeasure against these short-circuit defects 3a and 3b, a method of providing a plurality of signal lines / scanning line intersections and thin film transistors 7 as shown in FIG. In this case, the short-circuit defects 3a and 3d can be corrected by cutting the wiring at the wiring cutting positions 9a and 9d. However, when this method is actually applied, it is necessary to specify in advance the position where a short-circuit defect has occurred.

FIG. 3 shows a conventional inspection method for confirming the presence or absence of a short-circuit defect. In the case of this inspection method,
One end of each of the scanning lines 11 to 15 is commonly connected to the connection line 1c via the scanning line electrode terminal pads 11p to 15p and the external lines 11d to 15d, while the signal lines 21 to 25 are connected.
One end of each is also a signal line electrode terminal pad 21p.
To 25p, connection wiring 2c via external wirings 21d to 25d
Are commonly connected. In such a connection state, the probe is brought into contact with the connection wirings 1c and 2c, and a voltage V is applied between the scanning lines 11 to 15 and the signal lines 21 to 25,
If the current value is measured by the ammeter 4, the presence or absence of a short-circuit defect can be determined. However, according to this method, even if it can be confirmed that some kind of short-circuit defect has occurred, it is not possible to specify the pixel address where the short-circuit defect occurs. To specify the pixel address, the current value of the thin film transistor liquid crystal substrate having the wiring structure shown in FIG. 1 in a state where the voltage V is applied to only one of the scanning lines and any one of the signal lines is applied. The measurement should be performed sequentially for the combination of the scanning lines and the signal lines.
However, in this method, since the current value needs to be measured by the number of times the product of the number of scanning lines and the number of signal lines, the current measurement operation is not only complicated to specify the pixel address where the short-circuit defect has occurred. Would take a lot of time. In addition to such inconveniences, damage to the electrode terminals due to contact with the probe also poses a problem. In order to shorten the inspection time, it is conceivable to simultaneously contact a large number of probes. As a result, even if the pixel address where the short-circuit defect occurs can be specified, FIG.
As shown in (b), in a thin film transistor liquid crystal substrate having a plurality of intersections between scanning lines and signal lines and a plurality of thin film transistors, it is difficult to determine which intersection between the scanning lines and signal lines or the thin film transistor has a short-circuit defect. Cannot be specified.

On the other hand, apart from the above, as a method of shortening the inspection time, an electrochromic display panel is used.
A method of detecting a defect from the color formation state of the color forming film is described in Japanese Patent Application Laid-Open No. 1-154092. According to this method, the defective pixel can be specified because the color-forming film becomes non-color-formed or color-formed depending on the conduction state of each pixel electrode. However, in the case of using this method, since it is necessary to electrically connect the pixel electrode of the thin film transistor liquid crystal substrate and the coloring film of the electrochromic display substrate via the electrolyte, there is a problem of contamination when a liquid electrolyte is used. Further, when a solid electrolyte is used, a problem such as damage remains.

[0006]

As described above, in the prior art, short-circuit defects on a thin film transistor liquid crystal substrate cannot be detected with high sensitivity and quickly, which may damage the substrate itself. Is the actual situation. Even if the pixel address where the short-circuit defect exists can be specified, if the intersection of the scanning line / signal line or the thin film transistor itself is made for each pixel, any intersection or thin film transistor is used. It was impossible to identify whether a short-circuit defect existed in the device.

An object of the present invention is to provide a method and an apparatus for inspecting a thin film transistor liquid crystal substrate which can detect various short-circuit defects existing on the thin film transistor liquid crystal substrate with high sensitivity and without contact with the substrate and quickly. It is in.

Another object of the present invention is to determine which intersection or short-circuit defect has occurred in a thin-film transistor liquid crystal substrate having a plurality of scanning lines / signal line intersections or thin-film transistors themselves. An object of the present invention is to provide a method and an apparatus for inspecting a thin film transistor liquid crystal substrate which can be specified.

Another object of the present invention is to make various short-circuit defects existing between scanning lines and signal lines, between scanning lines, or between signal lines on a thin film transistor liquid crystal substrate non-contact with the substrate. An object of the present invention is to provide a method of inspecting a thin film transistor liquid crystal substrate that can be detected quickly.

Another object of the present invention is to increase the S / N ratio of a short-circuit defect existing between scanning lines and signal lines, between scanning lines, or between signal lines on a thin film transistor liquid crystal substrate. An object of the present invention is to provide a method for inspecting a thin film transistor liquid crystal substrate which can be detected without contact with the substrate.

It is another object of the present invention to provide a method of inspecting a thin film transistor liquid crystal substrate in which the position of a short-circuit defect existing in a pixel region on a thin film transistor liquid crystal substrate can be detected without contact with the substrate. It is in.

Another object of the present invention is to specify a pixel address where a short-circuit defect exists even in a thin film transistor liquid crystal substrate having a plurality of intersections between scanning lines and signal lines and a thin film transistor itself. It is an object of the present invention to provide a method for inspecting a thin film transistor liquid crystal substrate which can be quickly detected by making a short-circuit defect position in the pixel address non-contact with the substrate.

Another object of the present invention is to provide an apparatus for inspecting a thin film transistor liquid crystal substrate in which the above various methods for inspecting a thin film transistor liquid crystal substrate can be easily implemented.

[0014]

Means for Solving the Problems The present invention adopts the following characteristic items to achieve the above object.

A voltage is applied between the scanning line and the signal line of the thin film transistor liquid crystal substrate, and a change in a heat generation state caused by a current flowing through a short-circuit defect between the scanning line and the signal line is detected by an infrared image detector.

Each of the scanning lines and the signal lines of the thin film transistor liquid crystal substrate is electrically connected in common by one terminal.

The scanning lines existing between the terminals electrically connecting the scanning lines and the pixel region and the signal lines existing between the terminals electrically connecting the signal lines and the pixel region are described below.
By determining the change in the heat generation state before and after voltage application from the detected infrared image, the pixel address where the short-circuit defect has occurred is specified.

For the pixel portion where a short-circuit defect has occurred, the position where the short-circuit defect has occurred is specified by obtaining a change in the heat generation state before and after voltage application from the detected infrared image.

Detection of a change in a heat generation state before and after voltage application by using a difference or a quotient of infrared images.

For the pixel address where the short-circuit defect has occurred, the position where the short-circuit defect has occurred is specified by referring to the visible image of the wiring pattern of the thin film transistor liquid crystal substrate.

The sensitivity of the detector is detected by an infrared image detector whose sensitivity decreases as it approaches the light receiving portion.

Since there is a resistance of about several tens of mega-ohms between a scanning line and a signal line of a normal thin film transistor liquid crystal substrate, almost no current flows even when a voltage of about several tens of volts is applied between the scanning line and the signal line. Not flowing. On the other hand, when a short-circuit defect between the scanning line and the signal line exists in the thin film transistor liquid crystal substrate, a current flows through this short-circuit defect portion, and the short-circuit portion having a resistance value larger than the resistance of the normal wiring portion and This causes a phenomenon in which heat is generated around the periphery. When the heat generation state is detected by the infrared image detector, an image having a value proportional to the product of the emissivity γ and the fourth power of the temperature T is obtained. By the way, the value of the emissivity γ is close to 1 for glass, and close to 0 for chromium and aluminum which are wiring patterns, so that the observed image is affected by the difference in emissivity. Therefore, in order to detect minute heat generation with high sensitivity, it is necessary to eliminate the influence of the emissivity. Therefore,
By detecting images before and after voltage application and detecting the difference (quotient), it is possible to detect subtle state changes caused by minute heat generation at short-circuit defects, and to accurately identify short-circuit positions. It is.

For the pixel address where a short-circuit defect has actually occurred, referring to the visible image of the wiring pattern,
The position where the short-circuit defect occurs can be easily specified.

Further, the temperature distribution of the heat generating portion gradually decreases as the distance from the heat generating center increases. For this reason,
When the sensitivity of the detector is detected by an infrared image detector that decreases as it goes closer to the periphery of the light receiving unit, the peak position of the heat generation center can be accurately obtained.

The present invention also relates to an inspection method or an inspection apparatus for applying a voltage, heat, an electric field, or the like from the outside to detect a change in the state of the apparatus. This is an inspection method or an inspection apparatus that focuses on accurately calculating the position of a point or a region where a state changes by calculating a positional relationship between the image and a reference image. Further, the invention is characterized in that the reference image is an image before applying a voltage or the like, or a part thereof.

That is, according to the present invention, in order to achieve the above object, a voltage is applied between a scanning line and a signal line of a thin film transistor substrate, and a change in a heat generation state due to a current flowing through a short-circuit defective portion between the scanning line and the signal line. Detect with infrared image detector.

Each of the scanning lines and the signal lines of the thin film transistor liquid crystal substrate is electrically connected to one terminal.

The position where a short-circuit defect has occurred is specified by obtaining the change in the heat generation state before and after the voltage application from the detected infrared image.

By calculating the positional relationship between the infrared image and the reference image before voltage application, the heat generation position is accurately calculated.

The positional relationship between the images is determined by, for example, image matching.

Since a resistance of about several tens of megaohms exists between a scanning line and a signal line of a normal thin film transistor substrate, almost no current flows even when a voltage of about several tens of volts is applied between the scanning line and the signal line. Absent. In contrast, if there is a short-circuit defect between the scanning line and the signal line in the thin film transistor substrate,
A current flows through the short-circuit defective portion, and heat is generated in the short-circuit portion having a resistance value larger than that of a normal wiring portion and in the vicinity thereof. When this is detected by the infrared image detector, a value obtained by adding the product of the function R (T) of the object temperature T and the emissivity ε and the product of the function R (Ta) of the ambient temperature and (1−ε) Is obtained. The value of the emissivity ε is close to 1 for glass, and close to 0 for chromium and aluminum, which are wiring patterns, so that the observed image is affected by the outside world. Therefore, in order to detect minute heat generation with high sensitivity, it is necessary to remove the influence of the outside world. Therefore, by detecting the image before and after the voltage application and detecting the difference, it is possible to detect a subtle state change caused by minute heat generation of the short-circuited portion, excluding the influence of the outside world.

However, usually, many infrared image detectors have a point type detector and detect a two-dimensional image by scanning a mirror. In this configuration,
Reproducibility cannot be guaranteed, for example, the scanning position drifts over time. Further, even in the case of the two-dimensional type, if the lens has distortion, the short-circuit position cannot be accurately obtained. Therefore, by aligning the infrared image before voltage application and the reference infrared image, a correct short-circuit position can be measured.

Further, according to the present invention, in a state where a voltage is applied between scanning lines and signal lines, between scanning lines, or between signal lines in a thin film transistor liquid crystal substrate, the voltage is applied between the scanning lines and signal lines, between the scanning lines, or By detecting the change in the heat generation state due to the current flowing between the signal lines from the difference between the infrared image in the voltage application state and the infrared image in the voltage application stop state or the quotient, the scanning line / signal line is detected. A short-circuit defect existing between the scanning lines or between the signal lines is detected.
More preferably, the infrared image is detected after a predetermined time has elapsed from the time when the voltage was applied between the scanning lines and signal lines, between the scanning lines, or between the signal lines, while a predetermined time has elapsed since the time when the voltage application was stopped. Later, the infrared image is detected, and the change in the heating state due to the current flowing between the scanning line and the signal line, between the scanning lines, or between the signal lines is compared with the infrared image in the voltage application state and the voltage application stop state. The short-circuit defect is detected by detecting the difference from the infrared image or the quotient (ratio).

Further, according to the present invention, an infrared image is detected after a lapse of a predetermined time from the point of time when a voltage is applied between scanning lines and signal lines, between scanning lines, or between signal lines in a thin film transistor liquid crystal substrate. The detection of the infrared image is repeated a plurality of times after a lapse of a predetermined time from the time of the stop, and the change in the heat generation state due to the current flowing between the scanning line and the signal line, between the scanning lines, or between the signal lines. By detecting the difference between a plurality of superimposed infrared images in a voltage application state and a plurality of superimposed infrared images in a voltage application stop state, or a quotient, to obtain a scan line / signal line This is to detect a short-circuit defect existing between scanning lines or between signal lines.

Further, according to the present invention, a plurality of scanning lines and signal lines in a thin film transistor liquid crystal substrate are electrically connected in common on one terminal side, and a voltage is applied between the scanning lines and the signal lines. While the infrared image outside the pixel area is detected after a predetermined time elapses, the infrared image outside the pixel area is detected after a predetermined time elapses from the time when the application of the voltage is stopped, and the scanning line related to the change in the heat generation state is detected. And detecting the signal line from the difference between the infrared image with the voltage applied and the infrared image with the voltage stopped, or the quotient, to identify the coordinates where the short-circuit defect has occurred. It is to be.

Further, according to the present invention, after a pixel address in which a short-circuit defect has occurred is detected in a specified state, a voltage is applied to the difference infrared image at the pixel address between the scanning line and the signal line. The difference between the infrared image detected after a lapse of a predetermined time from the time when the infrared image was detected and the infrared image detected after a lapse of a predetermined time from the time when the application of the voltage was stopped, or the quotient, and the set threshold value Detect the short-circuit defect position by comparing,
Or, while detecting the wiring pattern position at the pixel address from the visible image at the pixel address, detecting the short-circuit defect position by comparing the wiring pattern at the pixel address with the wiring pattern at the adjacent pixel address is there.

Further, according to the present invention, in order that an image at an arbitrary position on the thin film transistor liquid crystal substrate can be optically detected, the thin film transistor liquid crystal substrate is positioned in the X, Y, Z directions and X direction.
A stage system in which the rotational position θ in the Y horizontal plane is mounted as an arbitrary state, and a voltage is applied between the scanning lines and the signal lines, between the scanning lines, or between the signal lines on the thin film transistor liquid crystal substrate mounted on the stage system. A voltage application system that allows application, and an illumination system that illuminates the thin film transistor liquid crystal substrate with visible light to detect a wiring pattern at an arbitrary position on the thin film transistor liquid crystal substrate mounted on the stage system as a visible image, An infrared image at an arbitrary position on the thin film transistor liquid crystal substrate mounted on the stage system is detected after a predetermined time has elapsed from the time when the voltage application is started and the time when the voltage application is stopped, and is short-circuited by performing predetermined image processing. An infrared image detection processing system for determining the presence / absence of a defect, identifying a short-circuit defect occurrence pixel address, and identifying a short-circuit defect position within the short-circuit defect occurrence pixel address; Detects a wiring pattern at an arbitrary position on the thin film transistor liquid crystal substrate mounted on the system as a visible image and performs predetermined image processing to identify the short-circuit defect position within the short-circuit defect occurrence pixel address. And an image detection processing system.

A short-circuit defect is detected from a difference image between an infrared image when a voltage is applied between scanning lines and signal lines, between scanning lines, or between signal lines, and an infrared image when voltage is stopped. However, at that time, by detecting the infrared image within a short time after the voltage application is stopped, the change in brightness near the short circuit caused by the diffusion of heat is offset, and the influence of the diffusion of heat is reduced. After the compensation, the presence or absence of the short-circuit defect and the position thereof are determined with high accuracy. Specifically, an infrared image is detected after a predetermined time has passed from the time when a voltage is applied between scanning lines and signal lines, between scanning lines, or between signal lines, while a predetermined time has elapsed since the voltage application was stopped. After the lapse of time, the infrared image is detected, and the change in the heat generation state due to the current flowing between the scanning line and the signal line, between the scanning lines, or between the signal lines is detected. The short-circuit defect is detected by detecting the difference from the infrared image in the state or the quotient.

The detection timing of the infrared image at that time is specifically determined by the current value detected in advance or the amount of heat generation.
In order to improve the S / N on the difference infrared image, the infrared image in each of the voltage application state and the voltage application stop state is detected a plurality of times, and then the voltage application state is determined. The short-circuit defect is detected from the difference infrared image between the superimposed image of the plurality of infrared images in the above and the superimposed image of the plurality of infrared images in the voltage stop state, and is detected in a more visible state. What you get. The presence or absence of a short-circuit defect can be generally detected by comparing the difference infrared image obtained as described above with a set threshold value.

Now, whether or not any short-circuit defect exists in the thin film transistor liquid crystal substrate can be detected with high accuracy as described above. However, from the viewpoint of improving the yield of the thin film transistor liquid crystal substrate, the short-circuit defect is particularly high. Is required to be detected in a state where its position is specified, and to be removed later by a laser beam. The pixel address where the short-circuit defect has occurred is the difference between the infrared image outside the pixel region when the voltage is applied between the scanning line and the signal line and the infrared image outside the pixel region when the voltage application is stopped, or Although it can be detected from the quotient, the difference infrared image at the pixel address (when the heat generation amount at the short-circuit defect position is large) or the visible image at the pixel address and the adjacent pixel address (short-circuit defect position) In this case, it is possible to easily detect at which position in the pixel address the defect has occurred from the case where the heat generation amount is relatively small.

[0041]

According to the present invention, according to the present invention, the scanning line and the signal line on the thin film transistor liquid crystal substrate, the adjacent scanning lines,
Alternatively, various short-circuit defects existing between adjacent signal lines can be quickly detected by bringing the short-circuit defect out of contact with the substrate. Also, in the present invention, the scanning lines on the thin film transistor liquid crystal substrate
The short-circuit defect position existing between the signal lines, between the adjacent scanning lines, or between the adjacent signal lines is increased in S / N, and is not in contact with the substrate, and can be detected quickly. Further, in the present invention, the short-circuit defect position existing in the pixel region on the thin film transistor liquid crystal substrate is brought into non-contact with the substrate,
In addition, it can be immediately detected as a pixel address. Further, in the present invention, even in a thin film transistor liquid crystal substrate having a plurality of scanning line / signal line intersections and thin film transistors themselves, a pixel address where a short-circuit defect exists is specified, and then the pixel address is determined within the pixel address. The short-circuit defect position is brought into non-contact with the substrate, and can be quickly detected. Further, according to the present invention, there can be provided an apparatus for inspecting a thin film transistor liquid crystal substrate in which the above various methods for inspecting a thin film transistor liquid crystal substrate can be easily implemented.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the theoretical background of the present invention will be described.

That is, since there is usually a resistance of about several tens of megaohms between a scanning line and a signal line on a normal thin film transistor substrate, a voltage of about several tens of volts is applied between the scanning line and the signal line. Is applied, almost no current flows. On the other hand, when a short-circuit defect exists between the scanning line and the signal line, a current flows through each of the scanning line and the signal line via the short-circuit defect portion. Generally, since the resistance value is larger than the resistance value in a normal wiring portion, the short-circuit defect portion and the vicinity thereof are in a heating state.

When an infrared image is detected, the infrared image is apparently read as described in the document "Principle and Method of Thermography Device" Thermoviewer "" (JEOL Ltd. Product Information). The product of the emissivity of the object (emissivity: defined as the ratio of the radiant energy of an object other than a black body to the radiant energy of a black body at the same temperature) and its function R (T) of its true temperature T; Reflectivity 1
−ε and the temperature of the reflection source (surrounding object) (normally room temperature) T ′
With the product of the function R (T '), that is, ε × R (T) +
An image having an apparent temperature of (1−ε) × R (T ′) as brightness is obtained. Here, the functions R (T) and R (T ') indicate the effective incident intensities corresponding to the temperatures T and T', respectively.

Since the value of the emissivity ε is close to 1 for glass and close to 0 for chromium and aluminum as wiring patterns, the observed image is affected by the difference in the emissivity ε. When the temperatures of the object and the reflection source are the same, the value of the image depends only on the function R (T) and is independent of the value of the emissivity ε. It is affected by the difference in the rate ε. The reflection source includes an objective lens in the infrared detector. Here, assuming that the temperatures of the target and the reflection source are equal, the value of the image depends only on the function R (T), so that the temperature of the target can be measured correctly. Therefore, in order to measure the temperature rise at the short-circuit defect portion, it is sufficient to detect the difference infrared image from the infrared images before and after voltage application. However, if attention is paid to the vicinity of the short-circuit defect portion, there is a temperature rise due to diffusion of heat. That is, in the vicinity of the short-circuit defect, the temperatures of the object and the reflection source are not equal, and the value of the image does not depend only on the function R (T). As a result, in the difference infrared image detected from the infrared image before and after the voltage application, the difference in the emissivity depending on the target location appears and the image looks like a pattern, and the image is short-circuited correctly from the difference infrared image. It is difficult to identify a defective portion.

As described above, in order to detect a heat generation position due to a short-circuit defect with high sensitivity, it is necessary to remove the influence due to the difference in emissivity. The effect of the above can be eliminated. In particular, if the infrared image is detected within a short time after the application of the voltage is stopped, the change in brightness near the short-circuit defect caused by the diffusion of heat can be offset. The detection of such an image has a greater effect than the detection of an infrared image within a short time after a voltage is applied. That is, in the latter, the heat transfer rate is increased, and the heat is transmitted through the glass substrate, so that the temperature near the short-circuit defect part immediately rises, whereas in the former, the temperature near the short-circuit defect part is increased. The diffused heat has a low heat transfer coefficient, is transmitted through the air, and does not immediately cool. Therefore, if the infrared image is detected within a short time after the voltage application is stopped, the temperature in the vicinity of the short-circuit defect does not change significantly, so that not only the detection of the short-circuit defect but also the position identification can be performed accurately. Things.

First, an embodiment of the present invention will be described with reference to FIGS.

First, the method of specifying a short-circuit pixel address will be described in detail with reference to FIG.
External wirings 11d to 15d formed outside the wirings 15p to 15p are electrically connected in common by the connection wiring 1c, and the signal lines 21 to 25 are connected to the external wirings 21d to 15d formed outside the electrode terminal pads 21p to 25p. 25d and the connection wiring 2c are electrically connected in common. In such a connection state, the scanning lines 11 to 15 and the signal lines 21 to 2
In order to apply the voltage V between the scanning line 13 and the signal line 2 as shown in FIG.
In the case where the current occurs in a pixel where 3 intersects, the current flows to the external wiring 13d → the electrode terminal pad 13p → the short-circuit defect 3 → the electrode terminal pad 23p → the external wiring 23d. This causes heat to be generated. At this time, if the resistance value at the short-circuit defect 3 is larger than that at the scanning line 13 and the signal line 23, even if the current is small, the amount of heat generated between the paths is large. 3 can be detected. That is, for example, the external wires 11d to 15d and the external wires 21d to
25d is detected by the infrared microscope along the broken line 6 before and after the voltage is applied, the difference between the detected image signals is calculated, and the projection in the X and Y directions is calculated, which is larger than the difference signal waveform shown in FIG. By detecting a position having a value, a wiring position in a heating state, that is, a scanning line 13 and a signal line 23 can be detected. As a result, the short-circuit pixel addresses of various short-circuit failures can be specified. At this time, instead of calculating the difference between the image signals detected by the infrared microscope, the quotient is calculated by division. Also, the short-circuit pixel address can be specified. In this example, when there are N short-circuits in the substrate, the number of detected scanning lines and signal lines is N at the maximum.

Now, the structure of the thin film transistor liquid crystal substrate inspection apparatus according to the present invention will be described. FIG. 5 shows an example of the structure. In this case, the inspection apparatus is roughly divided into a mechanism system 100, a voltage application system 101, and an optical system. Of these, the mechanical system is a θ stage (stage for rotation in a horizontal plane) 31, Z
A stage 32, an X stage 33, and a Y stage 34, and the thin film transistor liquid crystal substrate 30 is mounted on the θ stage 31, so that the thin film transistor liquid crystal substrate 30 can be positioned at an arbitrary position in the optical system visual field. I have. The position of the X stage 33 is detected by the position detector 53, but the same applies to the other Y stages 34 and the like. The voltage application system 101 includes a power supply 35, an ammeter 4, and probes 36a and 36b.
By bringing a and 36b into contact with the wiring pattern, a potential difference is given between the scanning lines and the signal lines, between the signal lines, or between the scanning lines. On the other hand, the optical system includes an infrared image detection processing system 102 and a laser beam irradiation system 10 for cutting the wiring.
3. It comprises a bright-field illumination system 104, a transmission illumination system 105, and a visible image detection processing system 106. The infrared image detection system includes an objective lens 37, a dichroic mirror 38, a lens 39, and an infrared image detector 5, and emits infrared light (wavelength range λ ₁ : About 3 to 13 μm, especially about 3 to 5 μm, or about 8 to 13 μm) is to be detected as an infrared image. In this infrared image detection system, the objective lens 3
7, the infrared image radiated from a minute area of about 1 to 20 μm, that is, the intensity of the infrared light can be detected in good condition. The laser light irradiation system 103 includes a laser oscillator 43, a beam expander 42, an opening 41 (having a moving mechanism not shown), and a dichroic mirror 40, and the laser light transmitted through the opening 41 is passed through an objective lens 37. By shrinking and projecting on the thin film transistor liquid crystal substrate 30, a wiring pattern at a desired position, specifically, a wiring pattern forming a short-circuit defect can be cut. It is obvious that the correction of the short-circuit defect is not limited to the laser beam, but may be any energy beam such as an ion beam or an electron beam. Bright field illumination system 1
04 also includes a lamp 46, a lens 45, and a half mirror 44, and illuminates the thin film transistor liquid crystal substrate 30 with visible light from above through an objective lens 37. Further, the transmission illumination system 105
Is composed of a lamp 50 and a lens 49, and the thin film transistor liquid crystal substrate 30 is illuminated with visible light from the back side thereof. Furthermore, the visible image detection system 1
Reference numeral 06 includes a visible image detector 48 and a lens 47. The visible image detector 48 is adjusted in advance to detect a visible image at the same position on the thin film transistor liquid crystal substrate 30 as the infrared image detector 5. In this embodiment, the objective lens 37 needs to transmit light from the visible region to the infrared region, and ZnS or the like may be used as the glass material. Further, the dichroic mirror 38 is an optical element that reflects light in the detection wavelength range λ ₁ of the infrared image detector 5 and transmits light shorter in wavelength than the detection wavelength range λ ₁ . Furthermore, the dichroic mirror 40 has a characteristic of reflecting the wavelength λ ₂ (λ ₂ <λ ₁ ) of the laser light from the laser oscillator 43 and transmitting visible light (wavelength range λ ₃ : λ ₃ <λ ₂ ). In this embodiment, the above-described voltage application, short-circuit pixel address specification, short-circuit position specification, and wiring correction are realized by one inspection apparatus.

The thin film transistor liquid crystal substrate inspection apparatus according to the present invention is configured as described above.
In operation, the thin film transistor liquid crystal substrate 30 disposed on the θ stage 31 has a probe 36
a, 36b are brought into contact with the wiring pattern,
Although a potential difference is applied between the scanning line and the signal line, an image before the potential difference is applied and an image after the potential difference is applied are detected as infrared images by the infrared image detector 5 via the objective lens 37.

More specifically, an infrared image in a voltage applied state is first detected after a lapse of a predetermined time T ₁ from the start of the voltage application, and the voltage application is stopped after a lapse of a predetermined time T ₂ from the stop of the voltage application. The infrared image in the state is detected. As shown in FIG. 10, the predetermined times T ₁ and T ₂ are generally different from each other, and are appropriately set based on a current value or a heat value detected in advance. For example, when the detected current value is large, both the heat generation amount and the heat diffusion amount are large, and in such a case, a relatively short time is set.
In addition, the current value increases when a plurality of short-circuit defects occur, but when the current value is high, an infrared image is detected in any case and the amount of heat generated at each short-circuit defect portion is evaluated. The predetermined times T ₁ and T ₂ need only be set appropriately. Incidentally, in FIG. 10, the predetermined times T ₁ , T ₂
Are set to about 165 ms and 0 to 300 ms, respectively.

The S / N ratio of the infrared image detected by the infrared image detector 5 is generally small, but in order to improve the S / N ratio, it is necessary to tune the voltage application and the voltage application stop.
The detection of the infrared image in each of the voltage application state and the voltage application stop state is repeated, and the detection is performed from a plurality of superimposed infrared images in the voltage application state and a plurality of superimposed infrared images in the voltage application stop state. The difference infrared image may be obtained by the difference image detection circuit 55 and then processed by the coordinate detection circuit 56. FIG.
FIG. 12 shows an example of a detection difference infrared image when tuning is performed for voltage application / stop and an example of a detection difference infrared image when tuning is not performed. It can be seen that if an infrared image is detected in time, the effects of thermal diffusion can be offset.

Returning to FIG. 5 and continuing the description, the coordinate detection circuit 56 processes the difference infrared image from the difference image detection circuit 55 to obtain the position corresponding to the maximum value in the difference infrared image. Is detected. The position is detected, for example, as the position of the center of gravity in an area surrounded by an isotherm that has dropped by 0.2 ° C., or the difference infrared image is projected in the X and Y directions within the setting area and is equal to or more than the set value. May be detected as the position of the center of gravity from the Y and X coordinates in each region having the value of Y, X in each region having a value equal to or greater than the set value
When the position of the center of gravity is obtained from the coordinates, the position of occurrence of the short-circuit defect is simultaneously obtained as the position of the center of gravity for a plurality of short-circuit defects. If a short-circuit defect has occurred in the pixel area, the short-circuit defective pixel address is specified first, then the short-circuit defect position within the pixel address is specified, and the short-circuit defect position is short-circuited. The defect removal processing is performed.

By the way, if the heat generation amount at the short-circuit defect portion is sufficiently large, the position of the short-circuit defect can be easily specified, but if not, the position can be specified from the visible image. I have.

Further, as shown in FIG.
7 is matched with the infrared image before voltage application, and is calculated as Y, X coordinates from a specific position such as the intersection of a scanning line and a signal line. Here, 58 is a difference image, and 59 is an infrared image before voltage application. The matching can be realized, for example, as follows.

When the image before voltage application is f (x, y) and the reference image is g (x, y), the value P (Δx, Δ
The values of Δx and Δy that minimize y) are obtained.

P (Δx, Δy) = ΣΣ (f (x−Δx, y−Δy) −g (x, y)) * (f (x−Δx, y−Δy) −g (x, y)) Here, Δx and Δy take values such as −2, −1, 0, 1, 2, and the like. If the reference image g (x, y) is selected so as to represent, for example, an area including the intersection of the signal line and the scanning line, where the intersection is located in the image before voltage application is determined by the obtained Δx, Δy. I understand. This enables accurate measurement even if the image has distortion. Reference image g (x, y)
May be a transistor to be disconnected. Although the image is affected by the outside world, the pattern has a different shade due to the difference in the emissivity of the pattern, and thus accurate matching can be realized. If the reference image g (x, y) is selected to be relatively small, the reference image g (x, y) is less likely to be affected by the difference in the amount of distortion in the image.

On the other hand, the image detected by the visible image detector 48 at the time of the transmitted illumination is binarized by the binarization circuit 61, and then interposed between the dictionary pattern from the dictionary pattern setting circuit 63 by the pattern matching circuit 62. Is performed, and the dictionary pattern position in the detected image is obtained. On the basis of the dictionary pattern position data and the coordinate data of the short-circuit candidate position and the wiring cutting position preset in the position coordinate data setting circuit 65, the short-circuit candidate position detecting circuit 64 calculates the short-circuit candidate position and the wiring cutting position. You. On the other hand, also in the bright field illumination, the visible image detector 4
The image detected in step 8 is temporarily stored in the memory 66,
The image in the short-circuit defective pixel address is subjected to pattern matching with the image in the adjacent pixel address by the pattern matching circuit 67, so that the pattern mismatch coordinates in the short-circuit defective pixel address are detected. Short circuit position determination circuit 6
In 9, the short-circuit candidate position closest to the pattern mismatch coordinates obtained by the pattern matching circuit 67 is determined as a true short-circuit position. By irradiating the laser beam from the laser oscillator 43 through the beam expander 42 in a state where the opening 41 is positioned based on this, the wiring at the desired position is automatically cut and the short-circuit defect can be corrected.

The outline of the operation of the thin film transistor liquid crystal substrate inspection apparatus according to the present invention has been described above. The above operation will be described more specifically and in detail as follows.

First, the method of specifying the short-circuit defective pixel address will be described with reference to FIG. 4. As shown, the scanning lines 11 to 15 on the thin film transistor liquid crystal substrate are drawn out to the external wirings 11d to 15d via the electrode terminal pads 11p to 15p. In addition, the signal lines 21 to 25 are also electrically connected in common by the connection wiring 1c,
It is drawn out to external wirings 21d to 25d via 1p to 25p, and is electrically connected in common by connection wiring 2c. In such a connection state, the scanning line 11
If a probe for applying a voltage is brought into contact with each of the connection wirings 1c and 2c to apply a voltage V between the signal lines 21 to 25 and the signal lines 21 to 25, for example, as shown in FIG. In the case where 3 occurs at a pixel address where the scanning line 13 and the signal line 23 intersect, the current is the external wiring 13d → the electrode terminal pad 13p → the short-circuit defect 3 → the electrode terminal pad 23p →
The current flows to the external wiring 23d, and the wiring between the paths generates heat due to the current. At this time, if the resistance value at the short-circuit defect 3 is larger than that at the scanning line 13 and the signal line 23, even if the current is small, the amount of heat generated between the paths is large. 3 can be detected. That is, for example, after the infrared images of the external wirings 11d to 15d and the external wirings 21d to 25d are detected by the infrared image detector 5 along the broken line 6 before and after the voltage is applied, the difference between the detected infrared images By calculating the projection distribution in the X and Y directions after obtaining the outside image, the wiring position having a large value is detected from the projection distribution, and the scanning line 13 and the signal line 23 in the heating state are detected. Can be detected. In this manner, the short-circuit defective pixel addresses of various short-circuit defects can be specified. In this case, instead of calculating the difference infrared image from the infrared image detected by the infrared image detector 5, Even when the quotient is calculated by division, the short-circuit pixel address can be easily specified. In this example, when there are N short-circuits in the substrate, the maximum number of scan lines and signal lines detected is N, respectively.
It becomes a book.

The above is a method of specifying a short-circuit defect in a pixel area on a pixel address. The position of a short-circuit defect between signal lines or between scan lines can be easily specified. When detecting a short-circuit defect between signal lines or scanning lines, a voltage is applied between adjacent signal lines or adjacent scanning lines, but the situation is the same in both cases. For simplicity, a method for detecting a short-circuit defect between scanning lines and a method for specifying its position will be described below.

That is, when detecting a short-circuit defect between scanning lines, the scanning lines at odd-numbered positions are commonly connected.
Similarly, the scanning lines at the even-numbered positions are also commonly connected, and a voltage is applied between the scanning lines at the odd-numbered positions and the scanning lines at the even-numbered positions. If a difference infrared image detected from the infrared image outside the pixel region in the voltage application state and the infrared image outside the pixel region in the stop state of the voltage application is projected in the X direction, the short-circuit defective pixel address can be specified. Similarly to the method, two scanning lines in a heat generating state can be detected as a pair in a state adjacent to each other from the projection distribution shape. From this, it is known that a short-circuit defect has occurred between the scanning lines. The occurrence position is, for example, the position of the short-circuit defect on the differential infrared image and the position of the thin-film transistor liquid crystal substrate at that time. It can be easily specified from the positioning state data. After the short-circuit defect position is specified in this manner, the short-circuit defect position can be removed by irradiating the short-circuit defect position with laser light. In the same manner, the presence or absence of a short-circuit defect between signal lines can be detected and the position of the short-circuit defect can be specified. From the distribution shape, the two signal lines in the heat generating state are detected as a pair in a state of being adjacent to each other.

Next, a method for specifying a short-circuit defect position in a short-circuit defect pixel address will be described. As shown in FIG. 6, a thin-film transistor liquid crystal substrate having a plurality of intersections of scanning lines and signal lines and a plurality of thin-film transistors 7 themselves is used. The short-circuit defect may occur in each of the short-circuit candidate areas 73a to 73d.
Therefore, it is necessary to specify (short-circuit position specification) in which of the short-circuit candidate areas 73a to 73d a short-circuit defect has occurred in performing the wiring correction later.

By the way, while the resistance value of a normal wiring is small, the resistance value of a short-circuit defect portion is not so small in general.
When this is detected by the infrared image detector 5, a value substantially proportional to the product of the emissivity γ and the square or the fourth power of the temperature T, that is, the product of the function R (T) of the object temperature T and the emissivity ε, An image having a value obtained by adding the product of the function R (Ta) of the ambient temperature and (1−ε) is obtained. Since the value of the emissivity γ is close to 1 for glass and close to 0 for chromium and aluminum, which are wiring patterns, it is affected by the outside world, and it is necessary to correct this difference in emissivity.

Although the resistance value in a normal wiring is small, that in a short-circuit defect portion is generally not so small, and a slight rise in temperature due to current occurs in that portion. So, with the procedure described above,
After detecting the infrared image before and after the voltage is applied in the short-circuit defect pixel address, and detecting the difference (or ratio) of the infrared image, a subtle image state change caused by minute heat generation at the short-circuit defect portion Can be detected with high sensitivity. By the way, detecting the difference (or ratio) infrared image itself is
As a result, an error of the infrared image detector 5 itself, for example, an error such as narcissus, is simultaneously compensated.

More specifically, assuming that the short-circuit defective pixel address has already been specified, each time the wiring pattern in that pixel address is sequentially positioned within the field of view of the infrared image detector 5. In addition, infrared images before and after voltage application are detected. If the difference (or ratio) detected from these infrared images is greater than or equal to a set threshold value (predetermined value) in the infrared image, a heat generation position due to a short-circuit defect is located in the pixel address. It is determined that the short-circuit defect position exists in the difference infrared image after it is determined that the short-circuit defect exists. The short-circuit defect position is detected, for example, as the position of the center of gravity in a region surrounded by isotherms, for example, 0.2 ° C. lower than the position corresponding to the maximum value in the difference infrared image, or the difference infrared image Is projected in the X and Y directions in the set area, and then detected as the barycentric position from the Y and X coordinates in each area having a value equal to or greater than the set value.

Then, as shown in FIG. 9, matching between the reference infrared image and the infrared image before voltage application is performed, and the Y and X coordinates from a specific position such as the intersection of a scanning line and a signal line are obtained. Is calculated as

In this manner, even when a plurality of short-circuit defects exist in the short-circuit defective pixel address, the short-circuit defect can be detected in a state where the positions are specified. In addition to the short-circuit defect position coordinates in the difference infrared image obtained in this way, the short-circuit candidate area where the short-circuit defect has occurred may be determined using the positioning coordinate data of the thin film transistor liquid crystal substrate.
As a result, the short-circuit defect 3 shown in FIG.
, And the wiring cutting position can be determined to be 9c, and the wiring may be cut at this wiring cutting position 9c.
By the way, when the value in the difference infrared image is less than the set value, the short-circuit defect position is identified by the visible image described later, or it is determined that the short-circuit defect does not exist in the short-circuit defect pixel address, The position of the short-circuit defect is not specified.

In the temperature distribution of the heat generating portion, the temperature gradually decreases as the distance from the heat generating center increases.
In the case of detecting an infrared image, the peak position of the center of heat generation can be more accurately detected by detecting the infrared image with the infrared image detector 5 whose sensitivity decreases as it approaches the light receiving portion from a constant detector. Required.

Note that, in addition to the heat generation at the short-circuit defect portion, the heat generation at the scanning line and the signal line caused by the short-circuit defect portion outside the intra-field difference infrared image is simultaneously detected in the in-view difference infrared image. However, by comparing the brightness at the end of the difference infrared image, the position of the short-circuit defect portion existing in the in-view difference infrared image can be correctly detected in a specified state.
FIG. 13 shows a state in which the brightness at the end of the difference infrared image in the visual field is compared. First, the case shown in FIG. 13A will be described. The in-field difference infrared image is shown in a rectangular display frame, and an image portion corresponding to a short-circuit defect portion (position coordinates ( X ₁ , Y ₁ ) S _1, so that the scanning line image (one end position coordinate Y ₁ ) and the signal line image (one end portion) having the image portion S ₁ as an intersection. Although the position coordinates X ₁ ) are both in a heat generating state, neither the scanning line image nor the signal line image extend in the direction of the other end, and the position coordinates of the other end cannot be detected. those capable of distinguishing the image portion S ₁ to be due to short-circuit defects. also, and FIG. 13 (B)
In the example shown in FIG. 5, there are two image portions S ₂ and S ₃ corresponding to two short-circuit defect portions near the in-field difference infrared image, and in this example, a scanning line image having the image portion S ₂ as an intersection. When the signal line image an image portion S ₃ and the intersecting portion are both adapted to appear in the visual field difference infrared image. Therefore, the end position coordinates for the scanning line image in the in-field difference infrared image are obtained as Y ₁ and Y ₂ , and those for the signal line image are obtained as X ₁ and X ₂ , but Y ₁ = Y ₂ , With X ₁ = X _2, the scanning line image and the signal line image can be distinguished from short-circuit defects outside the visual difference infrared image. Further in FIG. 13 (C), the image portion of the short-circuit defect portion corresponding to the field of view within the infrared image S ₄ is also present image portion S ₅ of the short-circuit defect portion corresponding to the outside in the difference infrared image field Although it is, and so these, the image portion S ₄ image portion S ₁ and the circumstances in FIG. 7 (a) is the same, the image portion S ₄ are those capable determines that due to a short-circuit defect. Image part S
_With respect to the signal line image having the intersection of ₅ , the end position coordinates are X ₁ = X ₂ , so that the signal line image can be determined to be due to a short-circuit defect outside the visual field. Incidentally, presence or absence of a short circuit defect at the position coordinates (X _1, Y ₂₎ is, it sets the window (broken line) in a state containing the position coordinates (X _1, Y ₂₎ in the interior, to repeat the above determination It is a good thing.

Further, in the above description, the image difference was taken to correct the emissivity. However, design data of the emissivity was prepared, corrected by the dimensions and sensitivity of the detector, and this data was calibrated, and after the voltage was applied, It is also possible to correctly determine the temperature from one image. Furthermore, if there is a geometric distortion in the detector,
It is also possible to detect and correct a wiring pattern such as a signal line.

As described above, the position of the short-circuit defect can be specified, but it is also possible to specify the position using the transmitted illumination image. This method will be described with reference to FIGS. 7A and 7B. If the resistance value of the short-circuit defect is small, the current due to the short-circuit is sufficiently large, and it is possible to specify the short-circuit pixel address using external wiring. But it is about the same as the wiring resistance,
Otherwise, when the infrared image is used, the heat generation at the short-circuit position is small, and this cannot be detected. That is, it is impossible to specify the short-circuit position in the pixel.

Next, a method of specifying a short-circuit defect position within a short-circuit defective pixel address by a visible image will be described.

When the resistance value at the short-circuit defect portion is small, the current due to the short-circuit is sufficiently large, and although the short-circuit defect pixel address can be specified by using the external wiring, the resistance value at the short-circuit defect portion is low. If the wiring resistance is about the same as or less than the wiring resistance in the short-circuit defective pixel, the short-circuit defect is detected at the short-circuit defective pixel address even if the heat generation at the short-circuit defect position is small and the difference infrared image is used. You won't get it. That is, it is impossible to specify the short-circuit defect position in the short-circuit defective pixel. The same applies to the case where the resistance value at the short-circuit defect portion is slightly larger than the wiring resistance in the short-circuit defect pixel. Therefore, although the short-circuit defective pixel address is specified by the above-described method, although it is determined that a short-circuit defect exists in the pixel address to some extent, the difference infrared image is determined. If the value in is smaller than the set value, the location of the short-circuit defect by the visible image is effective. Whether to actually specify the position of the short-circuit defect by the visible image is, specifically, in the difference infrared image,
The maximum value in the image is the brightness α at the end.
When an additional condition of (for example, α = 2) or less is satisfied, the position of a short-circuit defect is identified by a visible image for the first time.

Now, the method for specifying the short-circuit defect position using a visible image will be described in detail. FIG. 7A shows a visible image detected in a transmitted illumination state with respect to the wiring pattern shown in FIG. Since the transmitted illumination is performed from behind the thin film liquid crystal substrate, the metal wiring pattern can be detected as a silhouette image, that is, a binarized image as shown in the figure. On the other hand, in the dictionary pattern setting circuit 63 described above, the dictionary pattern shown in FIG.
5, the relative coordinate data of short-circuit candidate positions 74a to 74d and short-circuit positions 9a to 9d with the dictionary pattern position 77 as the origin are set in advance. I have. Therefore, if the position 77 of the dictionary pattern in the detected visible image is known, the short-circuit candidate positions 74a to 74d and the wiring cut positions 9a to 9d in the detected visible image are also uniquely determined. In the short-circuit defect position identification by the visible image, the wiring pattern in the short-circuit defect pixel address is inspected in a state where the detection positions are sequentially shifted, but the dictionary pattern position 77 in the detected visible image is the thin-film transistor liquid crystal substrate. The position 77 changes according to the positioning state, and the position 77 is obtained by pattern matching between the sequentially detected visible image and the dictionary pattern. That is, each time a visible image is detected under the transmitted illumination state, the pattern matching between the detected visible image and the dictionary pattern is performed, and the positioning coordinates in the state where the dictionary pattern best matches in the visible image are obtained. Is obtained from the position 77. Therefore, from the position 77, the coordinate data of the short-circuit candidate positions 74a to 74d and the wiring cutting positions 9a to 9d in the visible image can also be calculated.

On the other hand, the short-circuit defect position is obtained from a visible image detected from above, in this example, a gray-scale image. By performing pattern matching of the grayscale image pattern at the short-circuit defective pixel address with that at the adjacent pixel address, the coordinates at the mismatched pattern portion can be detected. Specifically, in the pattern matching, the grayscale image at each of the two pixel addresses adjacent to the short-circuit defective pixel address is shifted from the short-circuit defective pixel address by one pixel pitch in the left-right or vertical direction. Although it can be detected, a difference image between each of these two gray images and a gray image before shifting, that is, a gray image at a short-circuit defect pixel address is obtained. If a mismatched pattern portion having a value greater than or equal to the set value is commonly detected, the position coordinates at that portion may be detected as a short-circuit defect position. From this, the short-circuit candidate position 74a
Among the short-circuit defects, the one with the shortest distance to the short-circuit defect position is determined as a short-circuit candidate position where a short-circuit defect actually occurs. As a result, similarly to the above-described embodiment, it is found that the short circuit 3 shown in FIG. 6 exists in the short circuit candidate area 73c, and the wiring cutting position 9c can be determined as the wiring cutting position from the short circuit candidate area 73c. is there. As described above, in this example, the coordinate data to be set and stored in advance are the short-circuit candidate positions 74a to 74d and the wiring cut positions 9a to 9 when the origin is the dictionary pattern position 77.
In addition to d, short-circuit defect positions can be easily specified. After the wiring cutting position is determined by the short-circuit defect position specifying method described above, the short-circuit defect can be removed and corrected by cutting the wiring cutting position using an energy beam such as a laser beam. . In the above description, the visible image in the transmitted illumination state is used for detecting the position of the wiring pattern. However, the position of the wiring pattern can be detected from the visible image in the bright field illumination state.

Although the present invention has been described above, the present invention can be similarly applied to the presence or absence of a defect and the location of the target, if the object other than the thin film transistor substrate is accompanied by heat generation due to some defect factor. Obviously.

Finally, FIG. 8 shows an example of a detected image when the short-circuit pixel address is specified.

Incidentally, in the above-described embodiment of the thin film transistor liquid crystal substrate inspection apparatus, the case where the inspection of the short-circuit defect and the correction of the wiring are performed by one apparatus is shown, but the defect inspection and the wiring correction are performed by separate apparatuses. Of course, it may be possible. Needless to say, short-circuiting between signal lines and between scanning lines can be inspected in the same manner.

[0080]

As described above, according to the present invention, it is possible to detect various short-circuit defect defects in the wiring of the thin film transistor liquid crystal substrate with high sensitivity. In addition, contact for defect inspection is only voltage application to external wiring, and inspection can be performed without contacting the substrate body. Further, a short-circuit defect device can be specified even for a substrate on which a plurality of thin film transistors or a plurality of scanning line / signal line intersections are formed for each pixel of the liquid crystal display, and a short-circuit defect exists. It is possible to easily modify the substrate. As a result,
Various short-circuit defects existing on the thin film transistor liquid crystal substrate can be detected quickly with high sensitivity and without contact with the substrate, and if the wiring is corrected in parallel with such inspection, There is an effect that the yield of the thin film transistor liquid crystal substrate can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a general example of an electrical wiring configuration of a thin film transistor liquid crystal substrate.

FIGS. 2A and 2B are diagrams for explaining types of short-circuit defects and a method of correcting short-circuit defects.

FIG. 3 is a diagram for explaining an inspection method according to the related art for confirming the presence or absence of a short-circuit defect.

FIG. 4 is a diagram for explaining a short-circuit pixel address specifying method according to the present invention.

FIG. 5 is a diagram showing a configuration of an example of a thin film transistor liquid crystal substrate inspection apparatus according to the present invention.

FIG. 6 is a diagram for explaining a method of specifying a short-circuit position in a pixel.

FIGS. 7A and 7B are diagrams for explaining a short-circuit defect position specifying method based on a transmitted illumination image.

FIG. 8 is a diagram illustrating an example of a detected image when a short-circuit pixel address is specified.

FIG. 9 is a diagram illustrating a method of measuring a heat generation position.

10 is a diagram for explaining an example of infrared image detection timing in the inspection device shown in FIG.

11 is a diagram for explaining a qualitative feature of a difference based on an infrared image detected by the infrared image detection timing shown in FIG. 10: an infrared image.

12 is a diagram for explaining a qualitative problem of a difference based on a detected infrared image without depending on the infrared image detection timing shown in FIG.

FIGS. 13A to 13C show a signal line image or a scanning line image relatively remarkably appearing in a visual difference infrared image in identifying a short-circuit defect position in a short-circuit defect pixel. FIG. 7 is a diagram for explaining a processing method in a case.

[Explanation of symbols]

 3 Short circuit defect 9a, 9d Wiring cut position 30 Thin film transistor substrate 35 Power supply (DC, AC) 36 Probe tip 37 Objective lens 38, 40 Dichroic mirror 39, 45, 47, 49 ... Lens, 41 ... Aperture, 42 ... Beam expander, 43 ... Laser, 44 ... Half mirror, 48 ... Visible image detector, 55 ... Difference image detection circuit, 56 ... Coordinate detection circuit, 57 ... Reference infrared image 61, a binarization circuit, 62, a pattern matching circuit, 63, a dictionary pattern, 64, a short-circuit candidate position calculation circuit, 65, coordinate data, 66, a memory, 67, a pattern matching circuit, 69, a short-circuit position determination circuit, 74a 74d: short-circuit candidate position 77: dictionary pattern position

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G09G 3/36 G01R 31/28 L (56) References JP-A-1-185454 (JP, A) JP-A-2-64594 ( JP, A) JP-A-2-281133 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 25/72 G01R 31/00 G01R 31/302 G02F 1/133 G09G 3 / 36

Claims (16)

(57) [Claims] 1. A voltage is applied between the thin film transistor liquid crystal substrate of the scanning lines and the signal lines, while applying the voltage to obtain the infrared image of the thin film transistor liquid crystal substrate, the thin film tiger
Apply the voltage between the scanning lines and signal lines of the transistor liquid crystal substrate.
The thin film transistor is stopped in a state where the application of the voltage is stopped.
Obtain an infrared image of the resister liquid crystal substrate and apply the voltage.
TFT liquid crystal substrate inspection method and detecting defects of the thin film transistor liquid crystal substrate by using a state of the infrared state image and the application of the voltage was stopped infrared image. 2. An infrared image in a state where the voltage is applied and the infrared image
Obtain a difference image from the infrared image in the state where the voltage application is stopped.
2. The method for inspecting a thin film transistor liquid crystal substrate according to claim 1, wherein a defect of the thin film transistor liquid crystal substrate is detected from the difference image . 3. An infrared image of said thin film transistor liquid crystal substrate with said voltage applied and application of said voltage stopped.
2. The method for inspecting a thin film transistor liquid crystal substrate according to claim 1, wherein a plurality of infrared images of the thin film transistor liquid crystal substrate in a state are obtained, respectively, and the comparison is performed using the plurality of infrared images. 4. A method for detecting a short-circuit defect between a scanning line and a signal line of a thin film transistor liquid crystal substrate, comprising: changing a voltage applied between a scanning line and a signal line of the thin film transistor liquid crystal substrate; A method for inspecting a thin film transistor liquid crystal substrate, wherein a short circuit defect between the scanning line and the signal line is detected by comparing infrared images of the thin film transistor liquid crystal substrate before and after changing the voltage. 5. The method for inspecting a thin film transistor liquid crystal substrate according to claim 4, wherein the applied voltage is changed by switching between application and disconnection of the voltage. 6. A method for detecting a defect in a thin film transistor liquid crystal substrate, comprising: setting a potential difference between a scanning line and a signal line of the thin film transistor liquid crystal substrate to a first potential difference;
A first infrared image of the thin film transistor liquid crystal substrate is obtained in a state where the potential difference is set, and the second potential difference is set in the state where the potential difference is set to a second potential difference. obtain an infrared image, a thin film transistor liquid crystal substrate inspection and detects a defect of the prior <br/> Symbol thin film transistor liquid crystal substrate by comparing the first infrared image and the second infrared image Method. 7. The defect of the thin film transistor liquid crystal substrate is as follows:
7. The method according to claim 1, wherein the defect is a short circuit between the scanning line and the signal line. 8. A method for obtaining a plurality of first infrared images and a plurality of second infrared images, respectively, and using the first infrared image and the second infrared image obtained respectively. 7. The method for inspecting a thin film transistor liquid crystal substrate according to claim 6, wherein a defect of the thin film transistor liquid crystal substrate is detected. 9. A method for detecting a defect in a wiring of a thin film transistor liquid crystal substrate, the method comprising: applying a voltage between scanning lines and signal lines, between scanning lines, or between signal lines of the thin film transistor liquid crystal substrate. To obtain a first infrared image, and image the thin film transistor liquid crystal substrate in a state where the application of the voltage between the scanning lines and the signal lines, between the scanning lines, or between the signal lines is stopped. Second
And detecting a defect existing between the scanning lines and the signal lines, between the scanning lines, or between the signal lines by comparing the first infrared image with the second infrared image. A thin film transistor liquid crystal substrate inspection method. 10. A first infrared image obtained by imaging the thin film transistor liquid crystal substrate after a lapse of a first predetermined time from a point in time when a voltage is applied between the scanning line and the signal line, between the scanning lines, or between the signal lines. And after the second predetermined time has elapsed from the time when the application of the voltage between the scanning lines and the signal lines, between the scanning lines, or between the signal lines is stopped, the thin film transistor liquid crystal substrate is imaged and the second red 10. The method according to claim 9, wherein an outside image is obtained. 11. An infrared image is detected after a lapse of a predetermined time from when a voltage is applied between a scanning line and a signal line, between scanning lines, or between signal lines of a thin film transistor liquid crystal substrate, and the application of the voltage is stopped. Detecting the infrared image after a lapse of a predetermined time from the point in time is repeated a plurality of times, and detecting the infrared image is repeated a plurality of times. A plurality of infrared images obtained by superimposing a plurality of infrared images to obtain a first superimposed infrared image and repeating the detection of the infrared image a plurality of times in a state where the application of the voltage is stopped. A second superimposed infrared image is obtained by superimposing two infrared images, and the scanning line and the signal line are interposed using the first superimposed infrared image and the second superimposed infrared image. For short-circuit defects between scanning lines or between signal lines Thin film transistor liquid crystal substrate inspection method comprising and. 12. A plurality of scanning lines and signal lines on a thin film transistor liquid crystal substrate are electrically connected in common on one terminal side, and a predetermined time elapses from the time when a voltage is applied between the scanning lines and the signal lines. after one to detect the infrared image outside the pixel region, to detect the infrared image in the pixel area outside from the time the application is stopped after a predetermined time of the voltage, the scanning lines and the signal according to the change in the heat generation state Compare the infrared image with the line with the voltage applied to the infrared image with the voltage off
It allows a thin film transistor liquid crystal substrate inspection method characterized by detecting a pixel address of a short circuit defect is generated for. 13. A voltage applying means for applying a voltage between a scanning line and a signal line of a thin film transistor liquid crystal substrate, an infrared image detecting means for detecting an infrared image of the thin film transistor liquid crystal substrate, and the voltage applying means. An infrared image of the thin film transistor liquid crystal substrate detected by the infrared image detecting means before switching a voltage applied between the scanning line and the signal line ;
The voltage is applied between the scanning line and the signal line by the voltage applying unit.
After switching the voltage, the detection was performed by the infrared image detecting means.
Compare with the infrared image of the thin film transistor liquid crystal substrate
And a defect detecting means for detecting a short-circuit defect between the scanning line and the signal line. 14. The voltage applying means repeats switching of a voltage applied between the scanning line and the signal line, and the defect detecting means uses the voltage applying means to switch between the scanning line and the signal line. When the switching of the voltage applied to the scanning line is repeated, the scanning line and the signal are compared by comparing a plurality of infrared images of the thin film transistor liquid crystal substrate detected by the infrared image detecting means before and after the switching of each voltage. 14. The thin film transistor liquid crystal substrate inspection apparatus according to claim 13, wherein a short circuit defect between the lines is detected. 15. A voltage applying means for applying a voltage between wirings of a thin film transistor liquid crystal substrate at a predetermined cycle, and an infrared image of the thin film transistor liquid crystal substrate to which a voltage is applied at a predetermined cycle by the voltage applying means. an infrared image detection means for detecting a predetermined cycle differs from the timing of applying a voltage, given that to apply the voltage in the infrared image detection means
Defect detection means for detecting a short-circuit defect between the scanning line and the signal line using a plurality of infrared images of the thin film transistor liquid crystal substrate detected at a timing different from the cycle of the thin film transistor liquid crystal substrate. Board inspection equipment. 16. The thin film transistor liquid crystal substrate, to which a voltage is applied at a predetermined cycle by the voltage applying means, is connected between wirings of the thin film transistor liquid crystal substrate, between scanning lines and signal lines, between scanning lines, or between signal lines. 16. The inspection apparatus for a thin film transistor liquid crystal substrate according to claim 15, wherein