JPS6222455A - Thin film active device substrate - Google Patents

Abstract

PURPOSE:To repair perfectly and easily defects of the display using thin film active elements such as TFTs, by forming auxiliary wiring electrically insulated between separated electrodes or forming a section not intentionally being contacted electrically, to cause the up and down conduction through the wiring or the section by laser. CONSTITUTION:After amorphous silicon oxide is formed on a glass substrate, an amorphous silicon layer is formed. After it is patterned, Al is evaporated, and patterning forms a source line 2, source electrodes 3, 4, drain electrodes 5, 6 and auxiliary wiring 11. An amorphous silicon oxide layer is formed thereon as an insulating film by plasma CVD and an Al layer is evaporated by EB evaporation. After patterning forms a gate line 7 and auxiliary wirings 9A, 9B, dry etching opens a contact hole 8. Thereafter, EB evaporation forms an ITO film, and a lift-off method patterns a display pixel electrode 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tI film active element substrate in which a large number of thin film active elements are arranged near intersections of row and column electrodes.

[Prior Art] Recently, development of thin displays has been actively carried out due to demands for office automation equipment terminals, portable televisions, and the like. Among these, an active matrix system is being researched in which active elements are arranged at the intersections of the electrodes for driving in information display devices in which electrodes are arranged in rows and columns in order to accommodate large-capacity graphic displays. Figure 2 shows fil as a thin film active element.
(21) is a liquid crystal layer, and (22) is a switching transistor for driving the liquid crystal layer. (23) is a data line for applying the voltage necessary to drive the liquid crystal, and (20 is a selection signal line that controls the gate of the transistor (22). (25) and (2B) are It is a transparent electrode.

FIG. 3 shows a plan view of a conventionally known TPT having a coplanar structure. indicates the source electrode of each transistor, which is made of metal such as AI. Reference numeral (5) denotes a drain electrode, which is made of metal such as AI, like the source electrode. Reference numeral (7) denotes a gate line, which is made of metal such as AI, like the source electrode.

The contact hole (8) is made in the insulating film to insulate the source electrode (3) and the gate line (7), and is used to connect the drain electrode (5) and the display pixel electrode (10). It is. (1G) is the display pixel electrode,
It is formed from a transparent conductive film such as ITO or 5n02.

In addition, two or more thin film active elements may be formed and used on each display pixel electrode. For example, in an electrochromic display element (ECD), a liquid crystal display element (LCD) is used for driving the electrochromic display element (ECD).
), two TPTs are used for one pixel.

[Problems to be solved by the invention] As mentioned above, high-density information display with good visibility is possible by using thin film active elements, but at least one thin film active element is required for each pixel. Therefore, it is extremely difficult to produce a large number of thin film active devices without defects.

Defects caused by thin film active elements include structural defects such as short circuits between electrodes and disconnections between electrodes, and defects such as defects in thin film active element characteristics.

Mutual short circuits between electrodes occur due to dust in the interelectrode insulating film, but when there is a short circuit, the signal from one electrode escapes through the short circuit point, resulting in display defects such as line defects. It becomes the cause.

Furthermore, if the electrical characteristics of the thin film active element are poor, the thin film active element will not operate sufficiently even when a signal voltage is applied, resulting in a non-lighting defect when selected.

The number of such defects as described above varies depending on the management status of the manufacturing process, but at the level required for display quality, not even a single line defect is allowed, and even a point defect is 0.
It is necessary to keep it below 0.1%, but currently it is 20.
Substrates with zero or more lines often contain zero to a few line defects or several point defects, resulting in low cell yields and impeding the practical use of information display devices using thin-film active elements. This was the main obstacle.

A method for repairing such defects in a substrate requires two steps: cutting and connecting the defective portion.

As a cutting method, there are methods using a laser trimmer, an ultrasonic ivy, and the like. Examples of the connection method include vapor deposition using a focused ion beam and a method using a laser CVD method. Although the cutting method is relatively easy, the connecting method requires a large number of equipment and requires processes such as evacuation and gas introduction, which poses problems in substrate processing capacity.

: Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes: - A thin film active element substrate on which auxiliary wiring is provided in advance so that defects can be repaired using the auxiliary wiring. The present invention is intended to provide a thin film active element substrate in which electrodes are arranged in a matrix on an insulating substrate, and thin film active elements are provided near the intersections of the electrodes in the matrix, in which an insulating film is sandwiched, A thin film active element having a three-layer structure consisting of conductive thin films on the upper and lower sides, and at least a part of the three-layer structure being electrically connected in the vertical direction by laser irradiation. It is a board.

In the present invention, an electrically insulated auxiliary wiring is formed between electrodes that are separated by one, or a portion is intentionally left without electrical contact, and a laser beam is applied to these portions in the vertical direction. It is characterized by electrical connection by establishing continuity.

A brief explanation of the connection method using this method will be added here. A cross-sectional view of the three-layer structure is shown in Figure 4(a), where (41) is a glass substrate, (42) and (44) are conductive thin films, and (
43) shows an insulating g film. When a substrate with this structure is irradiated with a laser from above, it becomes shaped as shown in (b). At this time, the upper or lower conductive material covers the exposed surface of the insulating film, allowing electrical continuity between the upper and lower conductive thin films. Items in such a state did not show any change during the cleaning process, current test, etc. In addition, this auxiliary wiring can be formed at the same time as one of the electrodes arranged in a matrix, so not only does it add a repair function without increasing the number of steps, but it can also be patterned in advance to make it easier to connect. By devising the shape and arranging auxiliary wiring to deal with various defects, this method can be made easier and more reliable.For example, in the overlapped part of matrix electrodes, To repair the short circuit that has occurred,
An auxiliary electrode is formed in advance, and if a defect occurs, the defective part is electrically isolated.

It is also possible to eliminate display defects by cutting the electrode and connecting it via an auxiliary electrode.

In addition, in this method, compared to conventional repair methods, the laser trimmer used for cutting can be used as is, and a single device can have both cutting and connecting functions. Furthermore, since evacuation, gas introduction, etc. are not required, the substrate processing capacity can be greatly improved.

Furthermore, as a result of creating various active element substrates, defects can occur at any location, and the probability of adjacent active elements becoming defective is extremely low. If there is a defect in the active element, the defective part is deleted and the second active element is connected so that a second active element can be used, thereby eliminating line defects and single point defects and improving the yield of thin film active element substrates. enable.

Although the present invention can be applied to active elements such as thin film transistors and thin film diodes, the following description will be made using TPT as an example.

This will be explained below with reference to the drawings.

FIG. 1 is a plan view showing a typical structure of the TPT of the present invention. The whole structure has a coplanar structure. The structure has two resistors and an auxiliary electrode. (1) is a semiconductor layer made of amorphous silicon, polycrystalline silicon, microcrystalline silicon, etc., (2) is a source line made of metal such as AI, and (3) is a source electrode of a transistor of each pixel.

(0 indicates the source electrode of the second transistor, (5
), (8) indicate the drain electrodes of the first and second transistors, respectively, (7) indicates the gate line made of metal such as AI like the source and drain electrodes, (8)
) is a contact hole made in an insulating film for insulating the gate line and source line, and is for connecting the display pixel electrode (10) and the drain electrode (5).

(8A) and (3B) are auxiliary wiring according to the present invention.

Similarly to the gate electrode, it is made of a metal such as AI and may be formed at the same time as the gate electrode.Also, (11) is an auxiliary wiring made of a metal such as AI and may be formed at the same time as the source electrode. The auxiliary wiring using this conductive thin film is
Metal electrode such as AI, Cr, etc., 140. ．． Any transparent electrode such as 79n02 may be used and may be formed by a well-known method such as evaporation or sputtering, but by forming it simultaneously with the formation of the gate line or source line as in this example, it is possible to add an additional manufacturing process. It has the advantage that there is no need for However, similarly, the auxiliary wiring may be formed simultaneously with the formation of the display pixel electrode.

In the present invention, an auxiliary wiring (
11), and at the same time as the gate line is formed, two auxiliary wirings (9B) are formed for each overlapping part so that both ends are located on the source line and the auxiliary wiring (11). By adopting this configuration, the auxiliary wiring (8
B) and the source line (2), and the auxiliary wiring (IB) and the auxiliary wiring (11) are insulated, so even if there is a short circuit between the auxiliary wiring (11) and the gate line (7), the auxiliary wiring (1
As long as the source line (1) and the source line (2) are not electrically connected, the source line will not be affected and the number of defects will not increase.

Also, at the same time as forming the gate line on the source electrode (4) and source line (2) of the second transistor, the auxiliary wiring (
8A), and unless both the auxiliary wiring (8A), the source line (2), and the source electrode (4) are short-circuited or made conductive by laser, the second transistor will not connect to the source line. Since it is not connected, no defects will occur.

The drain electrode of the second transistor is overlapped with the display pixel electrode (lO) without using auxiliary wiring, but this also divides the drain electrode into two, with one being the drain electrode and the other being the display pixel electrode and the contact hole. You can connect the electrodes and provide auxiliary wiring to overlap both electrodes, or conversely, divide the display pixel electrode into two and connect both the electrode and the display pixel electrode with the drain electrode through a contact hole;
Auxiliary wiring may be provided to serve as an electrode.

In this example, if a gate-drain short circuit, gate-source short circuit, defective characteristics, etc. occur in the first transistor, this transistor is cut off at the A or B portion or both portions using a laser trimmer or the like. Then, the auxiliary wiring (θA
), and the second transistor You can make it work using . The state after repair is shown in FIG. 5. The electrodes are cut at parts A and H, and holes are made at (13) for vertical conduction by laser. There is a hole in the C part as well. This part shows that the laser is irradiated multiple times to ensure contact, and the gate line (7)
If a gate-source short circuit occurs at the subjunction (12) between the source line (2) and the source line (2), cut the source line at the part D and remove the auxiliary wiring (8B) and the auxiliary parts! At the overlapping part (14) of 1t (11) and the overlapping part (15) between the source line (2) and the auxiliary wiring (9B), it is possible to avoid defects and eliminate display defects by creating vertical conduction using a laser. become.

The above explanation deals with the case of coplanar fiTFT, but it also applies to stagger type, reverse stagger type, double gate type and Eurodisplay '84 Proc-eed
jngs p, 252
It can also be applied to a TPT with f-1=s, and is not particularly limited to the structure of the TPT.

In addition, we also form light shielding films, liquid crystal alignment films, color filters, polarizing plates, etc., and
It is also possible to form more than one, and various applications are possible.

[Operation] According to the TPT of the present invention, compared to the example shown in FIG. 3, defects caused by short circuits between electrodes can be easily repaired without changing the process at all, and a defect-free display can be achieved. With this method, the manufacturing yield can be easily brought close to 1.00%, so when using the TPT matrix panel as an information display device, it is much easier to use than the conventionally used dot matrix, etc. This can fully compensate for the disadvantages of high manufacturing costs.

``Example'' An example of a TPT using auxiliary wiring according to the present invention will be shown below.The structure of the TPT is the same as that shown in FIG. 1 above. 200 mm by plasma CVD method on a glass substrate.
Amorphous silicon oxide was formed using a mixed gas of silane gas and laughing gas. Thereafter, 2,000 amorphous silicon layers were formed using 100% silane gas.

This amorphous silicon layer was patterned into the shape shown in the figure by a photolithography process, and then AI was deposited by a 3000-person EB deposition method. After this,
By patterning, source line (2), source electrode (
3), (4), Drain electrodes (5), (8) and auxiliary wiring (11) were formed. Thereon, as an insulating film, an amorphous silicon oxide layer of 2,000 layers was deposited by plasma CVD, and an AI layer of 5,000 layers was deposited by EB evaporation. After this, first, a gate line (7) and auxiliary wirings (9A) and (9B) are formed by patterning, and then a contact hole (8) is formed by dry etching.
) was opened, then an ITO film was formed by EB evaporation, and a display pixel electrode (1o) was patterned using lift-off.

Using the method described above, 800μ layer pitch, 50
Ten Madrisk panels with 50 books were produced and compared with a TPT board as shown in Figure 3.

The decrease in aperture ratio due to the formation of the auxiliary wiring and the like of the present invention was on the order of several percent, and there was no problem at all in terms of display quality. Furthermore, when compared with conventional TPT, no increase in defects or deterioration of transistor characteristics due to the formation of auxiliary wiring was observed. A short circuit test was performed on this board, and the result was 0 to 3 short circuits per board, which is the same level as the conventional one.

The types of short circuits were two gate-source short circuits and one gate-drain short circuit. At the location where the gate-drain short circuit occurs, after cutting the root A of the source electrode and the drain electrode B at the point of the short circuit with a laser, cut the auxiliary wiring (
9A) with the source line (2) and source electrode (4) and the drain electrode (6) of the second transistor.
) and the display pixel electrode (10) overlap part C with 5JL1.
Repair was carried out by irradiating a single corner laser to establish continuity between the upper and lower sides, and connect it so that a second transistor could be used.

At the location where the gate-source short circuit occurs, after cutting both sides of the intersection of the source line and the gate line at the short-circuit point with a laser, cut the overlapping part (15) of the auxiliary wiring (9B) and the source line (2) Auxiliary arrangement! ! Irradiate the overlapped part (14) between (9B) and the auxiliary wiring (11) with a 5 square square laser to establish vertical continuity, bypass the gate-source short-circuit point, and connect the source line to repair it. I did it. As a result, the defect-free board was made into cells and the -C display quality was confirmed, and the display in the repaired area was no inferior to other areas, and the deterioration of characteristics was also repaired in reliability tests due to energization. There was no difference between the areas that were not treated.

[Effects of the invention] As described above, the present invention can reduce T by simply providing an auxiliary electrode.
Display defects using thin film moving elements such as FT can be completely and easily repaired. This can significantly reduce the defect rate of products, and compared to the dot matrix type that has been used in the past, it is possible to increase the manufacturing yield and keep manufacturing costs low, which was a problem with the active matrix type. The present invention can greatly contribute to the practical application of active Madrisk panels.

[Brief explanation of drawings]

FIG. 1 is a plan view showing a typical example of the TPT of the present invention in a state before conduction is established. FIG. 2 is a conceptual diagram of a typical example of an active matrix panel. FIG. 3 is a plan view showing an example of a conventional TPT. FIGS. 4(a) and 4(b) are cross-sectional views showing a state (a) before vertical continuity is established by a hydraulic system and a state (b) after it is established. FIG. 5 is a plan view showing the connection state of the TPT after repair. Semiconductor layer 2: Source line 3.42 Source electrode 5.6: Drain electrode 7: Gate line 8 Contact hole 9A, 98.11: Auxiliary wiring lO: Display pixel electrode ) (b) Figure 3

Claims (7)

[Claims] (1) A thin film active element substrate in which electrodes are arranged in a matrix on an insulating substrate, and thin film active elements are provided near the intersections of the electrodes in the matrix, with an insulating film sandwiched between them, and conductive thin films on the upper and lower sides. 1. A thin film active element substrate having a three-layer structure, and at least a part of the three-layer structure being electrically connected in the vertical direction by laser irradiation. (2) The thin film active element substrate according to claim 1, wherein at least one conductive thin film of the three-layer structure portion is an auxiliary wiring insulated from other conductive thin films. (3) Near the electrode intersection of the matrix-shaped electrodes, a second electrode is placed approximately parallel to one electrode, the first electrode, and the other electrode is the second electrode.
3. The thin film active element substrate according to claim 2, wherein auxiliary wiring is provided to cross the electrode. (4) A second auxiliary wiring having a three-layer structure formed by sandwiching an insulating film between one end of the auxiliary wiring and the first electrode and the other end of the auxiliary wiring. Thin film active device substrate. (5) The thin film active element substrate according to claim 3, wherein the auxiliary wiring is formed simultaneously with the first electrode. (6) The auxiliary wiring is formed simultaneously with the first electrode, and the second
5. The thin film active element substrate according to claim 4, wherein the auxiliary wiring is formed simultaneously with the second electrode. (7) A bypass of the first electrode can be formed by an auxiliary wiring and two second auxiliary wirings having a three-layer structure with an insulating film sandwiched between each end of the auxiliary wiring. 4
The thin film active element substrate described in .