JPH0778673B2 - Matrix-type image display device inspection device and its short-circuit inspection method, short-circuit defect repair method, point defect inspection method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, and more particularly to an inspection device and a correction method for an active image display device using liquid crystal as a display material.

2. Description of the Related Art In recent years, due to advances in microfabrication technology, high-density packaging technology, liquid crystal materials, etc., television images using liquid crystal panels are limited to 2-6 inch small ones, but on a commercial basis. It has come to be offered. In particular, by forming an RGB colored layer on one of the two glass plates forming the liquid crystal panel, the colorization of the display image can be easily achieved, and the switching element for each pixel can be easily achieved. In a so-called active type liquid crystal panel having a built-in LCD, an image with a high contrast ratio and less crosstalk is secured.

Such a liquid crystal panel has 120-240 scanning lines,
As a signal line, a matrix of 240 to 720 lines is generally used. Further, as a mounting method, as shown in FIG. 4, electrode terminal groups of scanning lines and signal lines formed on a matrix substrate 2 which is one of two substrates constituting the liquid crystal panel 1 (see FIG. (Not shown), for example, a polyimide-based resin thin film is used as a base, and a connection film 5 having a large number of gold-plated copper foil connection terminals (not shown) formed thereon is fixed by an adhesive while being pressed, or for driving. A means for supplying an electric signal to the central image display portion of the liquid crystal panel 1 by directly mounting the semiconductor integrated circuit chip 6 for supplying the electric signal is used. The wiring materials 3 and 4 for connecting the electrode terminal group necessary for mounting and the scanning lines and signal lines of the image display unit do not have to be made of the same material and are appropriately selected, but in a general simple matrix type liquid crystal panel , Both are transparent conductive
ITO (Indium-Tin-Oxide) is used.

Reference numeral 7 is another glass plate forming the liquid crystal panel 1 having a transparent conductive common electrode common to all the pixel electrodes, and the matrix substrate 2 and the glass plate 7 are arranged so as to maintain a gap of about 10 μm. It is assembled using members such as a spacer, a sealing agent, and a sealing material, and the gap is filled with a liquid crystal material. For coloring, a colored layer made of an organic thin film containing either or both of a dye and a pigment may be formed on the closed space side of the glass plate, and such a glass substrate 7 is also called a color filter. . And for example
When a TN type liquid crystal is used, the liquid crystal panel 1 functions as an electro-optical element by sticking polarizing plates on the upper surface of the glass plate 7 and the lower surface of the matrix substrate 2.

FIG. 5 is an equivalent circuit of an active type liquid crystal panel, in which a unit picture element including a thin film transistor 8 and a liquid crystal cell 9 is arranged as a switching element at each intersection of the scanning line 3 and the signal line 4. The elements drawn with solid lines are formed on one matrix substrate 2, and the elements drawn with broken lines are formed on the other glass substrate 7. Although the storage capacitor 10 is not necessarily an essential component, it reduces the utilization efficiency of the video signal and image unevenness caused by the parasitic capacitance between the gate and source, or the leakage current of the holding state of the thin film transistor 8 and the liquid crystal cell 9. Since it has an effect on the suppression of image flicker (flicker) and uneven brightness at the top and bottom of the screen (luminance gradient), it may reduce the aperture ratio or increase the number of point defects.
Adopted appropriately. 11 indicates all liquid crystal cells 9 as described above.
A counter electrode composed of a transparent conductive layer that is common to the storage capacitors 10 and 12 is a common line of the storage capacitors 10. Generally, 11 and 12 are connected and driven at the same potential.

As is well known, since an image display device is an object that is identified by a highly sensitive sensor of human vision, very severe restrictions are imposed on various defects, and not only line defects but also point defects, Compared to CRT, it is very strict and its exclusion is required. In other words, the device has low yield and is difficult to manufacture.

Regarding the inspection of defects, it is equivalent to a full-bit inspection in the case of a semiconductor memory, and it depends on the structure of the image display device. At the same time as checking quality, point defects are also inspected, and an inspection machine that can effectively detect defects that cause point defects in constituent materials, parts, or in the process is still in practical use. Not done.

A line defect is a defect which appears as a line on the screen literally, and the reason for its occurrence is relatively clear as described below. 1) The electrode lines such as the scanning lines and the signal lines were broken.
The main causes are 2) no electric signal reaches the electrode lines, 3) short-circuiting of a plurality of electrode lines, and 4) short-circuiting between the scanning lines and the signal lines. Currently, highly streamlined inspection equipment is not commercially available, even for those targeting line defects, and the probe (probe) is brought into contact with both ends of the electrode wire to disconnect the wire or short circuit between adjacent wires. This is a simple one to check the disconnection mainly on the electrode wire of the
The two-pronged inspection is performed, in which the probe is contacted with 10 scanning lines or signal lines all at once to find a short circuit with another signal line or scanning line, which is mainly used for defective analysis evaluation. ing.

It is needless to say that no line defect is allowed because it is an image display device.However, as shown in Japanese Patent Application No. 61-145237 previously filed by the present inventor for disconnection, It is possible to improve the apparent yield by incorporating a relief line capable of supplying an electric signal from both ends only to the broken electrode line. Therefore, even if the short-circuited portion can be cut or separated using some means, the same measure as the disconnection can be adopted. From the above viewpoint, the present inventor
No. 62-300815 discloses an image display device capable of inspecting disconnection and short circuit in a short time, but does not mention correction of short circuit. However, in an active matrix image display device with high added value, it is unavoidable that the yield is reduced especially when the screen size is large.
In Japanese Patent Application No. 62-276160 filed previously, a system is disclosed for correcting a short circuit by using an inspection device capable of precisely identifying a short circuit portion and a laser correction.

Problems to be Solved by the Invention The precise identification of a short-circuit point disclosed in Japanese Patent Application No. 62-276160 is composed of only a purely electrical detection system. Therefore, a means for supplying the inspection signal to all the terminals of the electrode wire is required. Even if it is unavoidable to confirm the image, it is not necessarily a good idea from the viewpoint of inspection cost to adopt a system having such a complicated mechanism even for inspection of disconnection or short circuit. Further, as described above, in COG (Chip-On-Glass) mounting in which a semiconductor integrated circuit chip for driving is directly connected to a matrix substrate, a probe head having several tens of probes is brought into contact with about 10 probes at a time. There is a problem in that it is necessary and a more complicated mechanism is required.

Moreover, the demand for point defect inspection is still strong, and the advent of a rational inspection device for point defects has been desired.

Means for Solving the Problems The present invention has been made in view of the above-mentioned current situation, and a plurality of scanning lines and signal lines are electrically connected in series on a matrix substrate so as to have inspection terminals at both ends. A matrix type image display device which is formed by forming an electric signal, means for supplying an electric signal to the inspection terminal, and means for addressing an arbitrary position in the matrix type image display device,
An infrared thermoviewer for measuring a temperature distribution on the matrix substrate is provided.

The present invention also includes a device provided with a laser for fusing a short circuit portion in the matrix type image display device.

Further, according to the short-circuit inspection method of the matrix type image display device of the present invention, an electric signal is applied to the pair of inspection terminals on the scanning line side and the pair of inspection terminals on the signal line side, which are formed into blocks, and the scanning lines and the signal lines are connected. When the short circuit between the scanning line and the signal line is detected by repeating the measurement of the leak current between and, the corresponding area is searched by the infrared thermoviewer to perform the precise identification of the short circuit portion.

Operation According to the present invention, the structure of the probe is simplified by forming a large number of electrode wires into blocks and providing inspection terminals at both ends thereof. And for blocks with shorts,
The existence of the short circuit can be detected by detecting the heat generation at the short circuit area by the infrared thermoviewer, and the line defect and the point defect can be detected.

In addition, a laser can be used to fuse the detected short-circuited portion to correct a line defect or a point defect.

Embodiment FIG. 1 and FIG. 2 show planar arrangements of respective electrode terminals in two embodiments of the present invention. FIG. 1 shows that, for example, 240 scanning lines are divided into four blocks (G1-G4) each of 60 lines and 360 signal lines are divided into six blocks (S1-S4) of 60 lines.
An example of the matrix substrate 2 divided into 6) and having electrode terminals arranged in the peripheral portion is shown. A pair of inspection terminals 13 and 14 are provided at both ends of the electrode terminal group 4 on the signal line side, and an inspection terminal 15 is provided at the center.
Is formed, and a pair of inspection terminals 16 and 17 are formed at both ends of the electrode terminal group 3 on the scanning line side. In the arrangement of Figure 1,
The upper blocks (S1, S3, S5) have odd-numbered terminal groups, and the lower blocks (S2, S4, S6) have even-numbered terminal groups. This is a general procedure for homogenizing the display image quality and reducing the driving power.

In the display device according to the present invention, all electrode lines in the block need to be connected in series. For that purpose, if the above-mentioned signal line side inspection terminal configuration is arranged, that is, if an odd-numbered electrode terminal group is arranged in the upper block and an even-numbered electrode terminal group is arranged in the lower block, the odd-numbered (1,3,5 ,. The upper end of the signal line of (...) is connected to the lower end of the corresponding odd-numbered electrode terminal, and the lower end of the signal line goes around the even-numbered electrode terminal and is the closest odd-numbered (3, 5, 7, ····) Between the first type return line to be connected to the lower end of the signal line and between the electrode terminals of the next and next closest signal lines (3-5, 7-9, ...).
A second type return line for connecting () is arranged. Similarly, the lower end of the even-numbered (2, 4, 6, ...) Signal line is connected to the upper end of the corresponding even-numbered electrode terminal, and the upper end of the same signal line goes around the odd-numbered electrode terminal. Between the electrode terminals of the first type return line and the closest next and next signal lines to be connected to the upper end of the even-numbered (4,6,8, ...) signal lines closest to each other ( 2nd connecting 4-6,8-10, ...
The seed return line is located. However, special consideration is required, including multi-layer wiring, so that the first type return line and the second type return line do not short-circuit even if they intersect.

Other methods are conceivable for connecting the signal lines in series.
An example is shown on the scanning line side in the figure. In this case, since the electric signals are all supplied from one side, one end of the scanning line is connected to one end of the electrode terminal, and the other end of the scanning line is in the direction in which the channel number of the scanning line increases. In addition, a return line connected to the adjacent scanning line and a return line connected to the adjacent electrode terminal in the direction in which the channel number increases also at the other end of the electrode terminal are required.

Since the return line is no longer needed after the electrical inspection is completed, it is formed in an area outside the cutting line 18 as shown in FIG. 1 and the inspection terminals 13-17 are formed after the electrical inspection or the panel assembly is completed. It may be removed by cutting together.

FIG. 2 shows a semiconductor integrated circuit chip for driving, which is COG-mounted on the matrix substrate 2 as described above. On the scanning line side, the semiconductor is formed on the electrode terminal 22 formed at the tip of the terminal group 3. The semiconductor chip 21 is mounted on the chip 20, and on the signal line side, the electrode terminal 23 formed at the tip of the terminal group 4. In this case, since the electrode wires are connected to the electrode terminals corresponding to the two adjacent channel numbers, in order to connect the electrode wires in series, the connecting wire connecting the adjacent electrode wires is the electrode wire or the electrode wire. It should be near the terminal. By properly selecting the material of the connecting line, it is possible to remove the connecting line by etching without losing the electrode lines such as scanning lines and signal lines. If necessary, connect the connecting line with an appropriate insulating film. Protect and
The opening may be formed on the connection line. Then, the series connection of the electrode wires may be released after the mounting of the semiconductor chip is completed. As in the case of FIG. 1, a pair of inspection terminals 16, 17 and 13, 14 are provided at both ends of the blocked electrode terminal groups 3, 4.
And are formed.

The inspection and correction method according to the present invention will be described according to the sequence shown in FIG. First, as described above, the matrix substrate having the inspection terminals is placed on the stage of the inspection machine. Next, a recognition (alignment) mark previously formed on the matrix substrate is optically recognized, and the matrix substrate is precisely positioned on the stage.
After that, the probe is brought into contact with the inspection terminal, and then the electrical inspection is started. A detailed description of the disconnection inspection will be omitted. The pair of inspection terminals 16 and 17 on the scanning line side are electrically connected to form one terminal, and the pair of inspection terminals 13 and 15 (FIG. 1) or 13 and 14 (FIG. 2) on the signal line side are electrically connected. Then, the leak current at the intersection of 60 × 60 scanning lines and signal lines is measured as the other terminal. The reason for electrically connecting the pair of inspection terminals is that even if there is a break in the electrode wire, the leak current at all intersections can be measured unless there are two or more breaks. If the leak current is smaller than the preset value, it may be determined that there is no short circuit portion in this block. The measurement of the leakage current is rationalized by dividing the image display unit into 4 × 6 blocks in this way. If no short circuit is found in the block inspection, the matrix substrate is passed to the next step as a non-defective product. On the contrary, if the number of short-circuited points is so large that the cover cannot be completed even if the laser is used for relief, the matrix substrate is discarded as a defective product.

Only the matrix substrate having a smaller number of short-circuit points than the preset number is observed with the infrared thermoviewer (not shown) in the corresponding block. If, for example, MODEL RM-2AS manufactured by Burns, Inc. in the United States is used as the infrared thermoviewer and MODEL NO.1780 is selected as the objective lens, a 3.2 mm square area is displayed on the CRT with a resolution of 30 μm. Since heat is generated by Joule heat at the short-circuited portion, the heat is detected by the above system and displayed on the CRT. Since the amount of heat generated is determined by the size of the leak current, the material and film thickness of the scanning line and signal line, etc., continuous use of a DC signal rather than a pulse signal as in block inspection The heat generation improves the detection sensitivity. If the 3.2 mm square area is smaller than the specified block, move the stage or infrared thermoviewer that describes the matrix substrate to observe the inside of the specified block.
It goes without saying that the heat generation status displayed above can be easily recognized not only visually but also automatically by image processing.

If the short-circuited portion between the scanning line and the signal line can be accurately identified, it is naturally possible to melt the scanning line or the signal line with a laser. In the present invention, in order to surely open the short circuit, 2
Although it is claimed that the parts are blown, this is because in an active image display device that incorporates a TFT (thin film transistor) as a switching element for each picture element, the scanning line Since a part of the gate electrode is used as the gate electrode, a short circuit between the gate electrode and the signal line occurs with a much higher probability than a short circuit between the scanning line and the signal line at the intersection. Which of the scanning line and the signal line is easily cut depends on the device structure, so it cannot be said unconditionally, but it is more advantageous to cut the scanning line from the viewpoint of power consumption.

In order to carry out the laser fusing, a positioning accuracy of the order of μm is required. On the other hand, since the crossing position of the scanning line and the signal line is clearly defined by the mask design, fully automatic laser fusing is possible if the location of laser fusing is predetermined. However, there is a possibility that the accuracy of fusing may decrease due to changes in the laser power and spot size, or changes in the film thickness of the conductive lines such as the scanning lines and signal lines that are about to be blown. It is important for ancillary work or ancillary process to confirm that the value is decreased or is below the specified value. Re-cutting with a laser is not impossible for a short circuit found by electrical re-inspection, but in general, there is a high possibility of secondary failure and it is advisable to discard it as a defective product.

Next, the point defect inspection according to the present invention will be described. Fifth
As is clear from the equivalent circuit in the figure, in the active matrix substrate in which the storage capacitor 10 is built in for each unit pixel, if the thin film transistor 8 is turned on, the storage capacitor
If 10 has a dielectric breakdown, a current path is formed from the signal line 4 through the thin film transistor 8, the storage capacitor 10, and the common line 12. The electrical resistance of the storage capacitor 10 in the state of dielectric breakdown is usually not sufficiently low, and therefore, the electric field is concentrated on the dielectric breakdown of the storage capacitor 10 and heat is also generated. Based on this principle, a potential of, for example, 20 V is applied to the scanning line blocks 16 and 17 and the signal line blocks 13, 15 or 13 and 14, the common line 12 is grounded (0 V), and an infrared thermoviewer is used to detect heat generation points. By searching, it is possible to detect the dielectric breakdown point of the storage capacitor 10, which is one of the causes of point defects.

When the storage capacitor 10 has a breakdown, the potential of the pixel electrode becomes the same potential as the common line 12, so when assembled into a liquid crystal panel, a black dot defect occurs in a normal black polarizing plate formation, and a normally white polarizing plate. There will be white spot defects in the composition.

The cause of the point defect is not only the short circuit of the storage capacitor but also the malfunction of the thin film transistor 8 and the contact defect between the thin film transistor 8 and the pixel electrode. These point defects cannot be detected in a configuration in which the unit pixel has only one thin film transistor 8 and one storage capacitor 10.

As described above, according to the present invention, a short circuit between a plurality of conductive paths that should originally be insulated such as a scanning line and a signal line is collectively inspected in a proper unit and short-circuited. It is possible to detect the line defect and the point defect of the high density and large area relatively easily because the existence can be precisely identified by observing the surface with the infrared thermoviewer only when the abnormality caused by is detected. be able to.

Further, by providing the laser, the detected short circuit can be immediately blown, and the line defect or the point defect can be immediately corrected immediately after the detection.

Therefore, the detection and repair of defects according to the present invention is more efficient with higher density and large area, that is, with more electrodes, and with fewer short circuits, in other words, the device fabrication technology reaches the industrialized level. The higher the efficiency, the higher the operational efficiency.

Further, automation of inspection and correction becomes extremely easy. Further, it is possible to use it as a point defect inspection machine for an active type matrix substrate having an auxiliary capacity for each picture element, and it is possible to provide an inspection apparatus of high practical value.

[Brief description of drawings]

FIG. 1 is a layout drawing showing the relationship between a group of electrode terminals divided around the matrix image display device and a test terminal,
FIG. 2 is a layout drawing of the inspection terminals when COG mounting is similarly applied, FIG. 3 is a diagram showing a sequence flow of the inspection and correction method according to the present invention, and FIG. 4 is mounting on a matrix type liquid crystal image display device. FIG. 5 is a perspective view showing the means, and FIG. 5 is a view showing an equivalent circuit of the device. 1 ... Matrix type liquid crystal image display device, 2 ... Matrix substrate, 3 ... Scanning line (terminal) group, 4 ... Signal line (terminal) group, 13, 14, 15, 16, 17 ... Inspection terminal, G1-G4 ……
Scan line block, S1 to S6 ... Signal line block.

Claims (6)

[Claims] 1. A plurality of scanning lines having electrode terminals on at least one end and a signal line, wherein the plurality of scanning lines or the signal lines are appropriately connected in series to form a block, And a matrix type image display device formed so as to have inspection terminals at both ends of each block, wherein a means for supplying an electric signal to the inspection terminals and an arbitrary position in the matrix type image display device are addressed. Means and
An inspection device for a matrix type image display device, comprising an infrared thermoviewer for detecting a temperature distribution on the matrix substrate. 2. The melting inspection apparatus for a matrix type image display device according to claim 1, further comprising a laser for cutting a short circuit portion between a scanning line and a signal line in the matrix type image display device. 3. A plurality of scanning lines having electrode terminals on at least one end and a signal line, wherein the plurality of scanning lines or the signal lines are appropriately connected in series to form a block, In addition, an electric signal is applied to the pair of inspection terminals on the scanning line side and the pair of inspection terminals on the signal line side in the matrix type image display device formed to have the inspection terminals at both ends of each block. Repeated measurement of the leak current between the scanning line and the signal line, and when a short circuit between the scanning line and the signal line is detected, the relevant area is searched by the infrared thermoviewer for precise identification of the short circuit location. A method for inspecting a short circuit in a matrix type image display device, which comprises: 4. When searching with an infrared thermoviewer,
4. The short circuit inspection method for a matrix type image display device according to claim 3, wherein the electric signal is direct current. 5. A plurality of scanning lines having an electrode terminal at least at one end and a signal line, wherein the plurality of scanning lines or the signal lines are appropriately connected in series to form a block, In addition, an electric signal is applied to the pair of inspection terminals on the scanning line side and the pair of inspection terminals on the signal line side in the matrix type image display device formed to have the inspection terminals at both ends of each block. Repeated measurement of the leak current between the scanning line and the signal line, and when a short circuit between the scanning line and the signal line is detected, the relevant area is searched by the infrared thermoviewer for precise identification of the short circuit location. After completion, the stage on which the matrix type image display device is placed or the irradiation port of the laser is moved so as to be fused by laser at two places with the scanning line or the signal line at the short-circuited portion interposed therebetween. Short defect correction method of the matrix-type image display apparatus. 6. A plurality of scanning lines having electrode terminals on at least one end and a signal line, wherein the plurality of scanning lines or the signal lines are appropriately connected in series to form a block, And a matrix type image display device formed so as to have inspection terminals at both ends of each block, wherein a means for supplying an electric signal to the inspection terminals and an arbitrary position in the matrix type image display device are addressed. Means and
When detecting a short circuit of the auxiliary capacitance of the matrix type image display device having an auxiliary capacitance for each picture element, the inspection device for a matrix type image display device equipped with an infrared thermoviewer for inspecting the temperature distribution on the matrix substrate ,
A matrix type image characterized by searching for a short circuit of the auxiliary capacitance with the infrared thermoviewer while applying an electric signal to a pair of inspection terminals on the scanning line side and a pair of inspection terminals on the signal line side which are blocked. Display device point defect inspection method.