JP2874252B2 - Active matrix substrate defect repair method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a defect repair method for an active matrix display device in which a driving thin film transistor is provided corresponding to a pixel, and a voltage is written to and held in a liquid crystal cell by using a switching action of the thin film transistor. Without increasing the parasitic capacitance and reducing the aperture ratio
An object of the present invention is to provide a thin film transistor capable of repairing a defect of an active matrix type liquid crystal display device, wherein a semiconductor thin film previously bonded via an insulating thin film on a supporting substrate is configured as an operating semiconductor layer, and A repairing thin film transistor having an electrode pad derived from an electrode is formed, and further, a repairing module substrate is prepared by removing a supporting substrate on the back surface of the repairing thin film transistor forming region, and display electrodes are formed on a surface by a matrix. The active matrix substrate provided with a thin film transistor corresponding to the display electrode is inspected, the detected defective thin film transistor is removed, and the repairing thin film transistor is placed on the trace of the removed thin film transistor through the electrode pad. Connection.

[Industrial applications]

The present invention relates to a defect repair method for an active matrix type display device in which a driving thin film transistor is provided corresponding to a pixel, and a voltage is applied to and held in a liquid crystal cell by using a switching action of the thin film transistor.

The active matrix display device is used as a thin display device for an information terminal together with a simple matrix display device, and a liquid crystal is used as a display medium.

Here, comparing the characteristics of the two, the active matrix type can perform the same operation as driving a large number of pixels independently, and therefore, even if the number of lines increases with an increase in display capacity, the simple matrix type As described above, the driving duty ratio is reduced, and problems such as a reduction in contrast and a phenomenon of a viewing angle do not occur. For this reason, the active matrix type liquid crystal display device can provide color display comparable to that of a cathode ray tube (CRT), and its use as a thin flat display is expanding.

However, in the active matrix type display device, it is necessary to form a switching element for each pixel, so that the number of elements becomes enormous, and the structure is complicated, so that the production yield is reduced and the cost is increased. .

[Conventional technology]

A conventional reciprocating method when a point defect occurs in an active matrix type liquid crystal display panel has been performed by adopting a redundant configuration in which a plurality of thin film transistors are provided for each pixel.

That is, as shown in FIG. 4, for each of a large number of pixels arranged in a matrix, a plurality of (two examples are shown in the figure) pixel driving thin film transistors T are provided, and a defect occurs. The thin film transistor is cut and separated, and the pixels are driven by the remaining thin film transistors.

In the figure, E is a display electrode, SB is a scan bus, and DB is a data bus.

[Problems to be Solved by the Invention] With the above-described conventional defect repair method using a redundant configuration, it is difficult to identify a thin film transistor having a defect. Since a plurality of pixels are provided for each pixel, there are problems such as an increase in parasitic capacitance and a decrease in aperture ratio.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a defect repair method for an active matrix liquid crystal display device that enables a defect repair of an active matrix liquid crystal display device without causing an increase in parasitic capacitance and a decrease in aperture ratio.

[Means for solving the problem]

The present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a view showing a section taken along the line II of FIG. 2, and FIG. 2 is a plan view showing one repairing thin film transistor according to the present invention.

In the figure, reference numeral 1 denotes a repair thin film transistor, and reference numeral 2 denotes an active matrix substrate.

A semiconductor substrate is pasted on the support substrate 11 via the insulating thin film 12 in advance, and is thinned. Using the semiconductor thin film 14 as an operating semiconductor layer, a thin film transistor and connection pads 15 derived from the gate electrode G, source electrode S, and drain electrode D of the thin film transistor are formed. Furthermore, the thin film transistor and the supporting substrate on the back surface of the connection pad formation region are removed, whereby the repairing thin film transistor 1 according to the present invention is obtained. Here, the back surface of the connection pad 15 is an insulating thin film
12 may be removed.

On the other hand, in the active matrix substrate 2, display electrodes (not shown) are arranged in a matrix on the surface of an insulating substrate 21 such as a glass substrate, similarly to a normal substrate.
A thin film transistor (not shown) is provided corresponding to the display electrode. The active matrix substrate 2 is inspected, and if a defect of the thin film transistor is detected, it is removed using a laser beam or the like.

Then, the repair thin film transistor 1 is formed on the trace of the thin film transistor removed on the active matrix substrate 2.
Connect to. To do so, the electrode pads 15 are overlaid on the corresponding connection electrodes 22 of the active matrix substrate 2 and both are connected.

The connection electrode 22 may be provided on the active matrix substrate 2 with an electrode dedicated to connection, or may be a gate bus line, a drain bus line and a display electrode to which the respective electrodes of the removed defective thin film transistor are connected. May be used.

The connection between the connection pad 15 and the connection electrode 22 can be easily performed by a method of irradiating a laser beam or applying ultrasonic waves.

Finally, the repairing thin film transistor 1 is separated from the support substrate 11 using a laser beam or the like.

(Operation)

As described above, according to the defect repair method for the active matrix substrate using the repairing thin film transistor, only one driving thin film transistor needs to be provided for each pixel on the active matrix substrate. Therefore, a defective thin film transistor can be easily detected.

Further, since a plurality of thin film transistors, which are problematic in a normal redundant configuration, are provided in the normal portion, an increase in parasitic capacitance and a decrease in aperture ratio can be suppressed.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

This embodiment is directed to an SOI in which a single crystal Si thin film is formed on an insulating film.
(Silicon On Insulator) Utilizing a technique for forming a substrate, for example, a wafer bonding method (Nikkei Micro Devices, March 88, pp. 82-98), a graphoepitaxy method, or the like can be used.

In this embodiment, about 4 μm formed on a silicon wafer is used.
An Si thin film having a thickness of about 0.5 μm is formed via an SiO ₂ film having a thickness of m, and a repair module substrate having a large number of repair thin film transistors is manufactured using this SOI substrate. Then, the repair thin film transistor is connected to the mark on the active matrix substrate from which the defective thin film transistor has been removed, to repair the defect.

That is, as shown in FIG.
The substrate 11 is used. Oxidized thickness of this Si substrate 11 is about 4
A μm SiO ₂ film 12 is formed.

Next, after bonding the Si single crystal substrate on this SiO ₂ film 12 using a wafer bonding method, the thickness of the Si single crystal substrate is reduced by polishing and etching, and the thickness is reduced to about 0.5 μm.
An m thin Si film 41 is formed.

Next, as shown in FIG. 3 (b), the Si film 14 is removed in a net shape, and small pieces of the Si thin film 14 are left in a matrix. Then, a thin film transistor is formed using each of them. In the figure, 15 is a connection pad, G is a gate electrode, S is a source electrode, and D is a drain electrode. Further, three regions 41 to 42 are drawn on the Si thin film 14, which are respectively a high-resistance channel region 41 and an n ⁺ doped n-type impurity.
Source and drain regions 42, 43 of the mold.

The above-mentioned gate electrode G. source electrode S and drain electrode D
Extend from the corresponding regions 41, 42, 43 to the outside of the small pieces of the Si thin film 14, and form the connection pads 15 thereon.

Next, plasma etching was performed from the back surface of the Si substrate 11 using CF ₂ + O ₂ as a reaction gas, and as shown in FIG. 3C, the Si substrate 11 on the back surface of the region where the thin film transistor and its connection pad were formed was removed. Remove.

Thus, the thin film transistor 1 for repairing defects in the active matrix according to the present invention is completed.

In this embodiment described above, as shown in FIG. 3D, a repair module substrate 3 in which one repair thin film transistor 1 is supported in each opening of the mesh Si substrate 11 is obtained. Can be

After aligning the repairing thin film transistor with the mark where the defective thin film transistor has been removed from the active matrix substrate, the connection pad 15 is connected to a predetermined portion of the active matrix substrate using an ultrasonic wave or a laser beam [see FIG. ], The repaired thin film transistor 1 is separated from the repair module substrate 3.

According to this embodiment described above, even if there is a defective thin film transistor on the active matrix substrate, it can be easily repaired. Therefore, there is no need to employ a redundant configuration, and only one thin film transistor needs to be provided for each pixel. This makes it easy to identify a defective portion and also prevents an increase in parasitic capacitance.

In the above embodiment, the supporting substrate 11 has been described using an example of using a Si substrate.However, if the Si substrate is used, various properties such as an expansion coefficient of the Si single crystal substrate match, so that the manufacturing process is facilitated. However, the present invention is not necessarily limited to the Si substrate, and an insulating substrate such as a glass substrate may be used.

In addition, although the starting material of the semiconductor thin film 14 serving as the operating semiconductor layer is a Si single crystal substrate, it may be a polycrystalline substrate, an amorphous substrate, or a semiconductor other than Si. The selection should be made in consideration of the relationship with the configuration of the active matrix substrate.

〔The invention's effect〕

As described above, according to the present invention, a defective thin film transistor in an active matrix substrate can be easily detected and a defect can be repaired. In addition, an increase in parasitic capacitance caused by providing a plurality of thin film transistors in each pixel can be achieved. Since this does not occur, the manufacturing yield can be improved without deteriorating the display characteristics.

[Brief description of the drawings]

1 and 2 are explanatory diagrams of the configuration of the present invention, FIG. 3 is an explanatory diagram of an embodiment of the present invention, and FIG. 4 is an explanatory diagram of a conventional problem. In the figure, 1 is a repair thin film transistor, 2 is an active matrix substrate, 3 is a repair module substrate, 11 is a support substrate (Si substrate), 12 is an insulating thin film (SiO ₂ thin film), 14
Denotes a semiconductor thin film (Si single crystal thin film), 15 denotes a connection pad, 22 denotes a connection electrode, G denotes a gate electrode, S denotes a source electrode, and D denotes a drain electrode.

Continuation of the front page (72) Inventor Masaaki Kobayashi 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-1-102518 (JP, A) (58) Fields investigated (Int. Cl. ^6, DB name) G02F 1/136 G02F 1/1343 G02F 1/13 101 G09F 9/30 H01L 29/78

Claims (2)

(57) [Claims] 1. A method for repairing a defect of an active matrix substrate, in which display electrodes are arranged in a matrix on a substrate surface and a thin film transistor is provided corresponding to the display electrodes, the method comprising operating a semiconductor substrate adhered on a support substrate. A thin-film transistor for repair comprising a semiconductor layer, and gate, source and drain electrodes, and a plurality of electrode pads derived from the respective electrodes is prepared, and a defect detected on the active matrix substrate is determined. A method for repairing a defect on an active matrix substrate, comprising: removing a thin film transistor; connecting the repairing thin film transistor to a portion corresponding to the substrate where the thin film transistor is removed via each electrode pad; and replacing the thin film transistor with the removed thin film transistor. 2. The method according to claim 1, wherein a semiconductor substrate previously bonded on a support substrate is constituted as an active semiconductor layer, and the gate, source, and drain electrodes have a dimensional relationship corresponding to a thin film transistor on an active matrix substrate to be repaired. For repairing a defect of an active matrix substrate, the repair substrate has a plurality of repairing thin film transistors having the derived electrode pads, and the support substrate is provided with cutouts for separating the repairing thin film transistors. Module board.