JP3270920B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for manufacturing a terminal portion of a TFT (thin film transistor) substrate of an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device has been used as a thin information terminal display device. As the liquid crystal display device, there are an active matrix type liquid crystal display device and a simple matrix type liquid crystal display device.

Among them, an active matrix type liquid crystal display device can perform the same operation as driving a large number of pixels independently, so that even if the number of lines increases with an increase in display capacity, it is simple. Unlike the matrix type liquid crystal display device, the duty ratio is reduced, and problems such as a decrease in contrast and a decrease in viewing angle do not occur. For this reason, the active matrix type liquid crystal display device has a CRT
Average color display can be obtained, and its use as a thin flat display is expanding.

In a conventional active matrix type liquid crystal display device, a drain terminal and a gate terminal connected to an external terminal of a tab type are formed of ITO for reliability after connection.
(A transparent electrode made of indium tin oxide). Therefore, in the manufacturing process, an electrochemical deposition method that applies a voltage to the drain bus is used, so that the ITO can be formed with a small number of masks. A TFT substrate compatible with both-side extraction of terminals including terminals was manufactured.

FIGS. 9 to 12 are views for explaining steps of manufacturing electrodes, wirings and terminals of a TFT (thin film transistor) substrate constituting a conventional active matrix type liquid crystal display device. In the intermediate steps of FIGS. 10 and 11, only the elements within the dashed line shown in FIG. 9 will be described. However, if all the elements have the same element type, the same processing is performed and the same configuration is obtained. is there.

First, as shown in FIG. 9, ITO and Cr are provided on an insulating substrate and patterned by a normal photolithography process to form an island-shaped drain terminal 1 and an island-shaped gate terminal 2. , A drain bus 3 and a pixel electrode 4 are formed.

Next, as shown in FIG. 10A, an electrochemical deposition method for applying a voltage to the drain bus 3, that is,
A resist film (not shown) is deposited on the drain bus 3 by an electrodeposition resist method, and Cr is etched using the resist film as a mask, thereby forming an island-like drain terminal 1, an island-like gate terminal 2, and an island-like gate terminal 2. Then, the ITO which is the lower conductive film of each of the pixel electrodes 4 is exposed.

[0008] Then, as shown in FIG. 10 (b), n ⁺
A contact layer such as type α-Si (amorphous silicon) was selectively deposited on Cr and ITO, and subsequently an active layer such as α-Si and a gate insulating film such as SiN were continuously formed on the entire surface. Thereafter, contact holes 5 and 6 for connecting the drain bus 3 and the drain terminal 1 and a contact hole 7 for connecting the gate bus and the gate terminal 2 are formed by a normal photolithography process.

Next, as shown in FIG. 11, after a conductive film such as aluminum is deposited, patterning is performed by a normal photolithography process to form a gate electrode 8, a gate bus 9, and a drain terminal 1 and a drain bus 3. Is formed.

Then, as shown in FIG. 12, the gate substrate 8 is completed by etching the gate insulating film and the active layer using the gate electrode 8, the gate bus 9, and the bridge 10 made of a conductive film of aluminum or the like as a mask. Things. The wiring layers running above and below the substrate to which each drain bus 3 is connected need to be cut and separated into drain bus units after the completion of the TFT substrate.

[0011]

However, FIG.
In the case of the structure described above, the existence of the drain bus 3 between the drain terminals 1 causes the substantial gap W between the drain terminals 1 (that is, the side opposite to the side end of the drain terminal adjacent to the side end of the drain bus). In other words, there has been a problem that a high alignment accuracy is required when connecting to an external terminal.

Accordingly, the present invention provides a TF for an active matrix type liquid crystal display device with a wide gap between drain terminals and capable of taking out both terminals without increasing the number of photomasks to be used by devising the manufacturing process.
It is intended to manufacture a T substrate.

[0013]

According to the present invention, there is provided a liquid crystal display device comprising:
A drain terminal (1 in FIG. 4) composed of an ITO film and a first conductive film provided thereon on an insulating substrate, a drain bus (3 in FIG. 4) formed integrally with the drain terminal, and a gate terminal ( After providing the pixel electrode (2 in FIG. 4) and the pixel electrode (4 in FIG. 4), a voltage is applied to at least the drain bus (3 in FIG. 4), and a mask member is selectively applied to a portion where the voltage is applied. A mask member is selectively deposited on at least the drain bus (3 in FIG. 4) by an electrochemical deposition method of depositing, and the first conductive film is removed by etching using the mask member as a mask. The ITO film, which is the lower conductive film, is exposed by exposing at least a part of the first conductive film on the drain terminal (1 in FIG. 4). Exposing membrane It is characterized in that to.

[0014]

Since the electrochemical deposition method is used to expose the ITO film as the lower conductive film of the pixel electrode, the number of photomasks used in the photolithography process is not increased, and the electrochemical Since the ITO film of the drain terminal is exposed by an etching process that does not use a static deposition method, the drain terminal and the drain bus can be integrally formed, and a portion running in parallel with the drain terminal of the drain bus is not required. Therefore, the gap between the drain terminals can be widened in the liquid crystal display device capable of taking both terminals out.

[0015]

1 to 4 are views for explaining a manufacturing process of a liquid crystal display device in which an electrodeposition resist process is performed before forming a TFT according to a first embodiment of the present invention. As in the description of the conventional example, only the elements within the dashed line shown in FIG. 1 will be described in the intermediate steps of FIGS.

First, as shown in FIG. 1, 500 ° ITO and 1500 ° Cr are continuously formed on an insulating substrate by sputtering, and are patterned by a usual photolithography process to form a drain terminal 1 and a gate terminal 2. , A drain bus 3 formed integrally with the drain terminal, and a pixel electrode 4.

In this case, the thickness of the ITO is 3
The film thickness of Cr may be 1 to 700 °.
It is good if it is 2,000 to 2,000Å.

Next, the substrate is immersed in the electrodeposition resist solution, and a voltage of 6 V is applied to the drain bus 3 (therefore, the drain terminal 1) and the gate terminal 2 for 20 seconds, so that the drain terminal 1, the drain bus 3, and the Then, an electrodeposition resist is attached to the upper surface of the gate terminal 2 (not shown).

Then, as shown in FIG. 2A, Cr is etched by using a Cr etchant, for example, an aqueous solution containing ceric ammonium nitrate and perchloric acid using the electrodeposited resist as a mask. Then, the ITO film as the lower conductive film of the pixel electrode 4 is exposed.

Next, as shown in FIG. 2B, after the electrodeposition resist is removed, an n ⁺ type α-Si contact layer is selectively deposited only on the ITO film and the Cr film of the substrate by the plasma CVD method. Followed by an α-Si active layer on the entire surface,
Then, a SiN gate insulating film is continuously formed. Then
An opening 11 at the center of the drain terminal 1, an opening 12 at the center of the gate terminal 2, and a contact hole 13 for connecting the gate bus and the gate terminal 2 are formed by a usual photolithography process.

The selective deposition process of the n ⁺ -type α-Si contact layer is carried out intermittently in a continuous hydrogen plasma atmosphere by phosphine (PH ₃ ) and silane (Si).
H ₄ ) is introduced by a plasma CVD method,
The hydrogen plasma allows selective deposition on the conductive film.

Next, as shown in FIG. 3A, after depositing 3000 ° of aluminum by a sputtering method,
The gate electrode 8 and the gate bus 9 are formed by patterning by a normal photolithography process. The thickness of the aluminum is 2000 to 40.
It is sufficient if it is 00Å.

Next, as shown in FIG. 3B, the substrate is immersed in a Cr etchant, and the Cr film exposed in the central opening 11 of the drain terminal 1 and the central opening 12 of the gate terminal 2 is removed. Then, the underlying ITO film is exposed. In this case, the gate insulating film substantially serves as an etching mask.

Next, as shown in FIG. 4, using a gate electrode 8 and a gate bus 9 made of aluminum as a mask, a SiN gate insulating film, an α-Si active layer, and n ⁺
The TFT substrate is completed by collectively etching the type α-Si contact layer. Also in this case, the wiring layers running above and below the substrate to which each drain terminal 1 is connected, and the wiring layer to which each gate terminal is connected are cut after completion of the TFT substrate, so that each drain terminal unit and each gate terminal unit are cut. Need to be separated.

FIGS. 5 to 8 are views for explaining a manufacturing process of a liquid crystal display device in which a TFT according to a second embodiment of the present invention is formed and then an electrodeposition resist process is performed. As in the description, in the intermediate steps of FIGS. 6 and 7, only the elements within the dashed line shown in FIG. 5 will be described.

First, as shown in FIG. 5, similar to the first embodiment, 500 DEG of ITO and 1500 DEG of
Is continuously formed by sputtering, and is patterned by a normal photolithography process to form a drain terminal 1, an island-shaped gate terminal 2, a drain bus 3 formed integrally with the drain terminal, and a pixel electrode 4.
To form

Also in this case, the film thickness of the ITO is
It is sufficient that the thickness is 300 to 700 °, and the thickness of Cr is
It is good if it is 1000-2000 °.

Next, as shown in FIG. 6A, an n ⁺ -type α-Si contact layer is selectively deposited only on Cr by a plasma CVD method, and subsequently, an α-Si active layer and a A SiN gate insulating film is continuously formed. Next, the central opening 11 of the drain terminal 1 and the gate terminal 2
Central opening 12, and gate bus and gate terminal 2
Is formed by a normal photolithography process.

Next, as shown in FIG. 6 (b), after depositing 3000 ° of aluminum by sputtering,
The gate electrode 8 and the gate bus 9 are formed by patterning by a normal photolithography process. The thickness of the aluminum is 2000 to 40.
It is sufficient if it is 00Å.

Next, as shown in FIG. 7A, the substrate is immersed in a Cr etchant, and the Cr film exposed in the central opening 11 of the drain terminal 1 and the central opening 12 of the gate terminal 2 is removed. Then, the underlying ITO film is exposed. Also in this case, the gate insulating film substantially serves as an etching mask.

Next, as shown in FIG. 7B, using a gate electrode 8 and a gate bus 9 made of aluminum as a mask, an SiN gate insulating film, an α-Si active layer, and n
^The Cr film is exposed by collectively etching the ⁺ type α-Si contact layer.

Next, the substrate is immersed in the electrodeposition resist solution, and a voltage of 6 V is applied to the drain bus 3 (accordingly, the drain terminal 1) for 20 seconds. Attach (not shown).

Next, as shown in FIG. 8, C exposed by a Cr etchant using the electrodeposition resist as a mask.
The r film is removed by etching to expose the ITO film as the lower conductive film of the pixel electrode 4, and finally, the electrodeposition resist is peeled off to complete the TFT substrate. Also in this case, the wiring layers running above and below the substrate to which each drain terminal 1 is connected need to be cut and separated into drain terminal units after the completion of the TFT substrate.

In each of the above embodiments, the electrodeposition resist method is used as the electrochemical deposition method. However, a conductive film having a selective etching property is selectively deposited on Cr and ITO by electrolytic plating. Alternatively, this conductive film may be used as a mask when etching Cr. Also,
This electrolytic plating method can be used at the time of forming the first electrode pattern. That is, in the above embodiment, patterning is performed after depositing ITO and Cr. However, only ITO is deposited and patterned, and
Cr may be selectively deposited on TO to form a two-layer electrode film made of ITO and Cr.

Further, in each embodiment of the present invention,
SiN is used as a gate insulating film.
"N" represents ordinary Si ₃ N ₄ or a silicon nitride film having a composition close to that of Si ₃ N ₄ , but is not limited to such a silicon nitride film, and may be another insulating film such as a silicon oxide film or alumina. Alternatively, as a material of the TFT, an amorphous semiconductor made of Si containing Ge (germanium) or C (carbon) may be used in addition to α-Si.

[0036]

According to the present invention, the gap between drain terminals can be widened with the same number of photomasks as in the conventional manufacturing method, so that the definition of the active matrix type liquid crystal display device can be improved.

[Brief description of the drawings]

FIG. 1 is a view illustrating a manufacturing process up to a middle of a method of manufacturing a TFT substrate according to a first embodiment of the present invention.

FIG. 2 is a view for explaining the manufacturing steps after FIG. 1 of the method for manufacturing a TFT substrate according to the first embodiment of the present invention.

FIG. 3 is a view for explaining the manufacturing steps after FIG. 2 of the method for manufacturing a TFT substrate according to the first embodiment of the present invention.

FIG. 4 is a view for explaining the manufacturing steps after FIG. 3 of the method for manufacturing a TFT substrate according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a manufacturing process up to a middle of a method of manufacturing a TFT substrate according to a second embodiment of the present invention.

FIG. 6 is a view for explaining the manufacturing steps after FIG. 5 of the method for manufacturing a TFT substrate according to the second embodiment of the present invention.

FIG. 7 is a view for explaining the manufacturing steps after FIG. 6 of the method for manufacturing a TFT substrate according to the second embodiment of the present invention.

FIG. 8 is a view for explaining the manufacturing steps after FIG. 7 of the method for manufacturing a TFT substrate according to the second embodiment of the present invention.

FIG. 9 is a diagram illustrating a manufacturing process up to halfway in a conventional method of manufacturing a TFT substrate.

FIG. 10 is a view for explaining the manufacturing steps after FIG. 9 of the conventional method for manufacturing a TFT substrate.

FIG. 11 is a diagram illustrating a manufacturing process of the conventional method for manufacturing a TFT substrate after FIG. 10;

FIG. 12 is a diagram illustrating a manufacturing process of the conventional method of manufacturing a TFT substrate after FIG. 11;

[Explanation of symbols]

Reference Signs List 1 drain terminal 2 gate terminal 3 drain bus 4 pixel electrode 5 contact hole for connecting drain bus and drain terminal 6 contact hole for connecting drain bus and drain terminal 7 connecting gate bus and gate terminal Contact hole 8 for gate electrode 9 gate bus 10 bridge 11 central opening of drain terminal 12 central opening of gate terminal 13 contact hole for connecting gate bus and gate terminal

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mari Hodachi 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Koji 1015 Kamikodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Stock In-company (56) References JP-A-6-194688 (JP, A) JP-A-6-59117 (JP, A) JP-A-4-365012 (JP, A) JP-A-2-153325 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1368 G02F 1/1343 G02F 1/1345

Claims (11)

(57) [Claims] 1. An electrode of a thin film transistor, a drain terminal formed of an ITO film on a insulating substrate and a first conductive film provided thereon, a drain bus formed integrally with the drain terminal, a gate terminal, and After providing a pixel electrode, at least a mask member is selectively formed on at least the drain bus by an electrochemical deposition method of applying a voltage to at least the drain bus and selectively depositing a mask member on a portion to which the voltage is applied. Depositing and removing the first conductive film by etching using the mask member as a mask to expose the ITO film which is a lower conductive film of the pixel electrode; and forming the thin film transistor on a substrate including the drain terminal. Forming a gate insulating film, and removing at least a part of the first conductive film on the drain terminal by etching; And removing the ITO film by removing. 2. The method according to claim 1, wherein the first conductive film is a lower conductive film of the pixel electrode.
2. The method according to claim 1, wherein the step of exposing the TO film is performed before forming the gate electrode and the gate bus. 3. The method according to claim 2, wherein the gate electrode and the gate bus are made of aluminum. 4. A step of applying a voltage to at least the drain bus, wherein a voltage is also applied to the gate terminal, and the mask member is selectively deposited on the gate terminal. A method for manufacturing a liquid crystal display device according to claim 2. 5. The method according to claim 1, wherein the lower conductive film is
2. The method according to claim 1, wherein the step of exposing the TO film is performed after forming the gate electrode and the gate bus. 6. The method according to claim 5, wherein the gate electrode and the gate bus are made of aluminum. 7. The step of applying a voltage to at least the drain bus is a step of applying a voltage only to the drain bus, and exposing the ITO film, which is a lower conductive film of the pixel electrode, 7. The method according to claim 5, wherein the first conductive film on the gate terminal is also removed to expose the ITO film. 8. The method according to claim 1, wherein said electrochemical deposition is an electrodeposition resist method. 9. The method for manufacturing a liquid crystal display device according to claim 1, wherein said first conductive film is a Cr film. 10. The method according to claim 1, wherein prior to the step of removing a part of the first conductive film on the drain terminal to expose the ITO film, the drain terminal, the drain bus, the gate terminal, and the pixel electrode. 2. The method according to claim 1, further comprising the step of selectively depositing a contact layer thereon by a plasma CVD method. 11. The method according to claim 10, wherein an amorphous silicon active layer and a gate insulating film are continuously deposited after depositing the contact layer.