JPH1195256A - Active matrix substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost and high performance TFT(thin film transistor) by enabling elimination of a source wiring forming process. SOLUTION: A metallic film is formed and a gate wiring 7, source wiring 9, a gate electrode, a source electrode, and a drain electrode are formed of a same material simultaneously. The gate wiring 7 is formed to be discontinuous with the source wiring 9 at their interconnecting part, but can be brought into a conductive state by being electrically connected with a bridge wiring via contact holes 8. Moreover, since a gate insulating film is formed between the gate wiring 7 and the source wiring 9, it is possible to keep an insulating state between them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active matrix substrate used for an active matrix type liquid crystal display device and the like, and more particularly to an active matrix substrate having a thin film transistor (TFT) formed on an insulating substrate.

[0002]

2. Description of the Related Art As a semiconductor device having TFTs on an insulating substrate such as glass, an active matrix type liquid crystal display or an image sensor using these TFTs as pixel switching elements is known.

The TFTs used in these devices include an amorphous silicon semiconductor (a-Si) or a crystalline silicon semiconductor (p-type) as a thin silicon semiconductor layer.
-Si) is generally used.

[0004] Inverted staggered TFTs using a-Si are most commonly used because of their low processing temperature, relatively simple manufacturing steps, and high mass productivity. However, physical properties such as conductivity are inferior to p-Si. Therefore, in order to obtain higher-speed characteristics, it is strongly required to establish a method for manufacturing a TFT made of p-Si.

In a TFT made of p-Si, in order to obtain higher-speed characteristics, it is desired to reduce the wiring resistance by using Al or an Al alloy for the wiring. However,
Since a heat treatment at about 400 to 600 ° C. is required in the step of forming a p-Si thin film or in the step of activating impurities, an inverted staggered structure in which a gate electrode is at the lowermost layer, such as a TFT made of a-Si, is used. Then, it becomes difficult to use Al as the wiring material. Therefore, a TFT made of p-Si
, It is common to use a top gate structure. However, a TFT having a top gate structure requires more steps because the number of steps increases and the process becomes complicated.

On the other hand, when an active matrix type liquid crystal display device using such a TFT is applied to a projector or the like, an increase in off-state current of a semiconductor layer or a change in a threshold voltage due to strong light entering the TFT. etc,
A new problem such as a change in characteristics or a decrease in reliability occurs. Therefore, a method of forming a light-shielding film for preventing light from entering the TFT below the channel of the TFT is often used.

[0007]

In order to manufacture an active matrix type liquid crystal display device using the above-described TFT, the light-shielding film, the gate wiring, and the source wiring are formed in separate steps. Since a material deposition step, a photo step, and an etching step are required, the number of steps is increased.

The present invention has been made in view of the above-described conventional problems, and has as its object to provide a low-cost, high-performance TFT that enables a reduction in the number of source wiring forming steps.

[0009]

According to another aspect of the present invention, there is provided an active matrix substrate comprising: a thin film transistor; a gate wiring; a source wiring; In an active matrix substrate having a light-shielding film provided in a lower layer, the gate wiring and the source wiring are formed of the same material, and the gate wiring or the source wiring is formed of the gate wiring and the source wiring. Are formed discontinuously at the intersections, and a cross-linked wiring is formed at the intersections with the same material as the light shielding film.

According to a second aspect of the present invention, in the active matrix substrate having a thin film transistor, a gate wiring, and a source wiring on an insulating substrate, the gate wiring and the source wiring are formed of the same material. And the gate wiring or the source wiring is formed discontinuously at the intersection of the gate wiring and the source wiring, and a bridge wiring is formed at the intersection with the same material as the semiconductor film forming the thin film transistor. It is characterized by being.

According to the active matrix substrate of the present invention, the gate wiring and the source wiring are formed of the same material, and the gate wiring or the source wiring is formed discontinuously at the intersection of the gate wiring and the source wiring. Since the bridge wiring is formed of the same material as the light shielding film at the intersection, the gate wiring and the source wiring can be simultaneously formed in the same step, and the light shielding film and the bridge wiring are formed in the same step. It can be formed simultaneously.

Further, the gate wiring and the source wiring are formed of the same material, and the gate wiring or the source wiring is formed discontinuously at the intersection of the gate wiring and the source wiring, and a thin film transistor is formed at the intersection. Since the bridge wiring is formed of the same material as the semiconductor film to be formed, the gate wiring and the source wiring can be simultaneously formed in the same step, and the semiconductor film and the bridge wiring are simultaneously formed in the same step. Can be.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1) FIG. 1 is a process diagram showing a cross section of a TFT, FIG. 2 is a process diagram showing a cross section of an intersection between a gate wiring and a source wiring according to FIG. 1, and FIG. FIG. 4 is a plan view showing an intersection between a gate wiring and a source wiring.

As shown in FIGS. 1 (a) and 2 (a), after cleaning the surface of an insulating substrate 1 made of, for example, glass having an outer size of about 300 mm × 300 mm, a thin metal film such as Ta is sputtered. Thickness 1 using the method
The metal thin film is processed into a predetermined shape of the light shielding film 2 by performing a photolithography and an etching process. The light-shielding film 2 is not formed only in the lower part of the TFT which is the original purpose as shown in FIG. 1A, but is not formed between the gate wiring and the source wiring as shown in FIG. Cross-linking wiring 3 formed at the intersection
And

Next, a silicon oxide film (SiO ₂ ) or a silicon nitride film (SiN) is deposited as the insulating thin film 4 to a thickness of about 100 to 500 nm using a chemical vapor deposition (CVD) method or a sputtering method. Let it. And
A-Si5 is deposited as a semiconductor film on the insulating thin film 4 to a thickness of about 50 to 100 nm using a CVD method, and photolithography and etching are performed to form a-Si5.
Is formed in a predetermined shape, and a-Si5
Is crystallized.

Next, as shown in FIGS. 1B and 2B, a gate insulating film 6 is deposited and formed into a predetermined shape by photolithography and etching. At this time, as shown in FIG. 2B, a contact hole 8 for connecting the gate wiring 7 and the bridging wiring 3 is formed in the gate insulating film 6. Then, impurity ions are implanted into the a-Si5 using a known technique, and activated by laser light or the like.

Further, as shown in FIG. 2B, a contact hole 8 for connecting the gate wiring 7 and the bridging wiring 3 is formed in the insulating thin film 4. Then, a metal film is formed to form the gate wiring 7 and the source wiring 9, and FIG.
The gate electrode 10, the source electrode 11, and the drain electrode 12 shown in FIG.

As shown in FIGS. 2B and 3, the gate wiring 7 is formed discontinuously at the intersection with the source wiring 9, but is electrically connected to the bridge wiring 3 via the contact hole 8. The connection can be made conductive. Further, since the gate insulating film 6 is formed between the gate wiring 7 and the source wiring 9, the insulating state can be maintained. In this embodiment, the gate line 7 is discontinuous, but the source line 9 may be discontinuous.

Thereafter, as shown in FIGS. 1C and 2C, an interlayer insulating film 13 is formed by using a known technique, and as shown in FIG. 1C, a contact hole 14 and a pixel electrode are formed. 15 are formed.

(Embodiment 2) FIG. 4 is a process diagram showing a cross section of another TFT, FIG. 5 is a process diagram showing a cross section of an intersection between a gate wiring and a source wiring according to FIG. 4, and FIG. 3 is a plan view showing an intersection between a gate wiring and a source wiring according to FIG.

As shown in FIGS. 4 (a) and 5 (a), after cleaning the surface of an insulating substrate 1 made of glass having an outer size of, for example, about 300 mm × 300 mm, the insulating thin film 4 is made of SiO ₂ or SiN is deposited to a thickness of about 100 to 500 nm using a CVD method or a sputtering method.

Then, a-Si5 is deposited as a semiconductor film on the insulating thin film 4 to a thickness of about 50 to 100 nm by a CVD method, and photolithography and etching are performed to form the a-Si5 into a predetermined shape. Once formed, a-Si5 is crystallized using known techniques. The a-Si 5 is not formed only in the TFT region which is the original purpose as shown in FIG. 4A, but is formed at the intersection between the gate wiring and the source wiring as shown in FIG. To form a bridge wiring 3.

Next, as shown in FIG. 4B and FIG. 5B, a gate insulating film 6 is deposited and formed into a predetermined shape by performing photolithography and etching steps. At this time, a contact hole 8 for connecting the gate wiring 7 and the bridging wiring 3 is formed in the gate insulating film 6.

Then, impurity ions are implanted into the a-Si 5 by using a known technique, and activated by laser light or the like. At this time, impurity ions are also implanted into a-Si forming the cross-linked wiring 3 and activated by laser light or the like.

Further, a metal film is formed, and the gate wiring 7 and the source wiring 9, and the gate electrode 10, the source electrode 11 and the drain electrode 12 are simultaneously formed of the same material.

As shown in FIGS. 5B and 6, the gate wiring 7 is formed discontinuously at the intersection with the source wiring 9, but is electrically connected to the bridge wiring 3 through the contact hole 8. The connection can be made conductive. Further, since the gate insulating film 6 is formed between the gate wiring 7 and the source wiring 9, the insulating state can be maintained. In this embodiment, the gate line 7 is discontinuous, but the source line 9 may be discontinuous.

Thereafter, as shown in FIGS. 4C and 5C, an interlayer insulating film 13 is formed by using a known technique, and as shown in FIG. 4C, a contact hole 14 and a pixel electrode are formed. 15 are formed.

[0029]

As described above, according to the active matrix substrate of the present invention, the gate wiring and the source wiring are formed of the same material, and the gate wiring or the source wiring is formed of the gate wiring and the source wiring. Are formed discontinuously at the intersections of the two, and the bridge wirings are formed at the intersections with the same material as the light shielding film, so that the gate wirings and the source wirings can be simultaneously formed in the same process, Since the film and the cross-linked wiring can be formed simultaneously in the same process, the manufacturing process can be simplified and an active matrix substrate can be obtained at low cost.

Further, the gate wiring and the source wiring are formed of the same material, and the gate wiring or the source wiring is formed discontinuously at the intersection of the gate wiring and the source wiring, and a thin film transistor is formed at the intersection. Since the bridge wiring is formed of the same material as the semiconductor film to be formed, the gate wiring and the source wiring can be simultaneously formed in the same step, and the semiconductor film and the bridge wiring are simultaneously formed in the same step. Therefore, the manufacturing process can be simplified and an active matrix substrate can be obtained at low cost.

[Brief description of the drawings]

FIGS. 1A to 1C are process diagrams showing a cross section of a TFT.

FIGS. 2A to 2C are process diagrams showing cross sections of intersections between a gate wiring and a source wiring according to FIG. 1;

FIG. 3 is a plan view showing an intersection between a gate wiring and a source wiring according to FIG. 1;

FIGS. 4A to 4C are process diagrams showing cross sections of another TFT.

5 (a) to 5 (c) are process diagrams showing cross sections of intersections between gate lines and source lines according to FIG.

6 is a plan view showing an intersection between a gate wiring and a source wiring according to FIG. 4;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 light-shielding film 3 cross-linked wiring 4 insulating thin film 5 a-Si 6 gate insulating film 7 gate wiring 8 contact hole 9 source wiring 10 gate electrode 11 source electrode 12 drain electrode 13 interlayer insulating film 14 contact hole 15 pixel electrode

Claims (2)

[Claims] 1. A thin film transistor on an insulating substrate,
In an active matrix substrate including a gate wiring, a source wiring, and a light shielding film provided below the thin film transistor, the gate wiring and the source wiring are formed of the same material, and the gate wiring or the source is formed. An active matrix substrate, wherein a wiring is discontinuously formed at an intersection of the gate wiring and the source wiring, and a bridging wiring is formed at the intersection with the same material as the light shielding film. 2. A thin film transistor on an insulating substrate,
In an active matrix substrate having a gate line and a source line, the gate line and the source line are formed of the same material, and the gate line or the source line intersects the gate line and the source line. An active matrix substrate, wherein the active matrix substrate is formed discontinuously in a portion, and a bridging wiring is formed at the intersection with the same material as a semiconductor film forming the thin film transistor.