JPH079520B2 - Method for manufacturing active matrix liquid crystal display device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing an active matrix liquid crystal display device which is a liquid crystal display for displaying an image of a television or the like.

[Prior art and its problems] An active matrix liquid crystal display device using TFT (thin-film transistor) is composed of ITO (Indiun (In) -Tin (Sn) -Oxide) on a transparent insulating substrate such as crows. The transparent pixel electrodes are formed in a matrix, and TFTs are arranged in an array corresponding to the pixel electrodes. This TFT is used for plasma / CVD of semiconductor films and insulating films.
It is formed by laminating by a method and etching into a desired shape. When this plasma / CVD method is used, hydrogen is present in the plasma, so that the conductive film made of an oxide such as ITO is reduced and its composition is changed to deteriorate the resistance value, the transmittance, and the like.
Therefore, the pixel electrode made of ITO needs to be adhered and formed after the step of forming and arranging the TFTs.

Therefore, conventionally, an active matrix liquid crystal display device is manufactured by a method as shown in FIGS. That is, as shown in FIG. 2A, the surface of the transparent insulating substrate 1 such as glass is washed. Metal (Cr,
Al, Ta, etc.) is vapor-deposited to form a metal film, and then the metal film is subjected to a first photolithography process (resist coating,
Exposure, phenomenon, etching, etc.)
As shown in FIG. 3B, the gate electrode 2 and the gate line (not shown) are formed on the surface of the insulating substrate 1.

After this, the gate electrode 2 and the gate line (not shown)
Over the insulating substrate 1 to form an insulating film (Si-N) and an amorphous silicon film (a-Si: H) on the insulating substrate 1 by a plasma / CVD method, and these are formed by a second photolithography process. As shown in c), the gate insulating film 3 and the amorphous silicon film 4 are formed so as to cover the gate electrode 2 and the gate line.

After that, a metal film (Al or the like) is vapor-deposited so as to cover the gate insulating film 3 and the amorphous silicon film 4, and a third photolithography process is performed, so that the source as shown in FIG. An electrode 5, a drain electrode 6 and a drain line (not shown) are formed.

Then, finally, a transparent conductive film made of ITO is formed on the insulating substrate 1 by vapor deposition or the like so as to cover the source electrode 5, the drain electrode 6, and the drain line (not shown). The pixel electrodes 7 are formed in a matrix on the insulating substrate 1 by the photolithography process of the first time. In this case, each of the pixel electrodes 7 overlaps a part of the source electrode 5 and is electrically connected to the source electrode 5.

However, in such a manufacturing method, the photolithography process of sequentially performing resist coating, exposure, development, etching and the like must be repeated four times, resulting in poor productivity and yield, resulting in high cost. There was a problem.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the number of times of photolithography processing to simplify the manufacturing process, and to achieve low cost and high quality. An object of the present invention is to provide a method for manufacturing an active matrix liquid crystal display device capable of obtaining the above.

[Summary of the Invention] In order to achieve the above-mentioned object, according to the present invention, a transparent conductive film and a metal film are laminated on a transparent insulating substrate in a first step, and the transparent conductive film is formed in a second step. And a conductor formed of a metal film, the pixel electrode portion is formed in a matrix, and a conductive portion including an electrode portion and a line portion connected to the electrode portion is formed between the pixel electrode portions, and the conductor is formed. A plurality of transistor element regions are formed by laminating an insulating film and an amorphous semiconductor film on a predetermined portion above, and in the third step, among the metal films, the metal film laminated on at least the pixel electrode portion is formed. And removing the transparent pixel electrode to form a transparent pixel electrode,
The essential point is that the conductor film connected to the semiconductor film in the transistor element region is formed into a predetermined shape in the step of.

[Embodiment] An embodiment of the present invention will be described below in the order of steps with reference to FIGS. 1A and 1B.

In FIG. 1A (A) (a), 10 is a transparent insulating substrate such as glass. After cleaning the insulating substrate 10, a transparent conductive film 11 made of ITO (Indiun (In) -Tin (Sn) -Oxide) is vapor-deposited on the upper surface of the insulating substrate 10 to a thickness of about 500 Å, and on the transparent conductive film 11. Metal film made of metal such as Cr, Ni, Mo
Evaporate 12 to a thickness of about 1000Å. After that, each of the laminated films 11 and 12 is subjected to a photolithography process to form an insulating substrate.
A large number (only one is shown in the figure) of pixel electrode portions 15 are formed in a matrix on the gate electrode 10, and a gate electrode 13 and a gate line portion 14 corresponding to the pixel electrode portions 15 are formed. That is, a metal film is formed by applying resist, exposing and developing.
By forming a resist pattern (not shown) on 12 and covering the metal film 12 in a predetermined shape with this resist pattern, and etching the remaining exposed metal film 12 and the transparent conductive film 11 thereunder, As shown in FIGS. 1A (A) (A), a transparent conductive film is formed on the insulating substrate 10.
A gate electrode 13, a gate line portion 14, and a pixel electrode portion 15 composed of 11 and the metal film 12 are formed.

Next, as shown in FIGS. 1A (B) and (B), the gate insulating film 16 and the two-layer amorphous silicon film 17 are continuously formed by plasma / CVD so as to cover the metal film 12. In this case, the gate insulating film 16 is made of silicon nitride (Si ₃ N
₄ ) and is deposited to a thickness of about 3000Å. Two
The layer amorphous silicon film 17 is composed of an active amorphous silicon layer (ia-Si) 17a and an ion-doped amorphous silicon layer (n ⁺ -a-Si) 17b, and the thickness of the lower active amorphous silicon layer 17a. Is about 3000Å, and the upper amorphous silicon layer 17b is about 300Å. In this case, even if the gate insulating film 16 and the two-layer amorphous silicon film 17 are formed by the plasma / CVD method, the ITO
Since the transparent conductive film 11 made of is protected by the metal film 12, the composition of the conductive film 11 does not change due to reduction of the conductive film 11 by hydrogen in plasma. Thereafter, the laminated gate insulating film 16 and the two-layer amorphous silicon film 17 are patterned by photolithography to form a transistor element region. That is, amorphous silicon film
When a resist pattern is formed on 17 and the gate insulating film 16 and the two-layer amorphous silicon film 17 are etched by this resist pattern (not shown), FIG. 1A (B)
As shown in (b), the gate insulating film 16 and the two-layer amorphous silicon film 17 are left only in a portion which covers a part of the gate electrode 13 and the gate line portion 14.

Thereafter, as shown in FIGS. 1A (C) and (c), unnecessary portions of the metal film are removed by etching from the transparent conductive film 11 and the metal film 12 which are initially formed in layers. That is, the above
The exposed metal film 12 is etched using the amorphous silicon film 17 formed by the process shown in FIGS. 1A (B) and (B) as a resist. Then, the pixel electrode portion 15 becomes the transparent pixel electrode 15a composed only of the ITO transparent conductive film 11, and the gate line portion 14 which is not covered with the amorphous silicon film 17 is also composed only of the ITO transparent conductive film 11. It becomes the transparent gate line film 14a.

Next, as shown in FIGS. 1B (D) and (d), 1 μm of aluminum (Al) is formed so as to cover the transparent conductive film 11 made of ITO and the amorphous silicon film 17 from which the metal film 12 is removed.
The metal film 18 is vapor-deposited to a thickness of about m, and the metal film 18 is formed into a predetermined pattern by photolithography. That is, a resist film 19 is formed on the metal film 18, exposed and developed, and then the metal film 18 is etched to form a drain electrode.
20, the drain line 21, and the source electrode 22 are formed, and the metal film 18 is formed on the gate line film 14a made of the transparent conductive film 11. At this time, the resist film 19 on the metal film 18
Leave. The source electrode 22 is formed from the amorphous silicon film 17 to the end of the metal film 12 of the pixel electrode portion 15, and is electrically connected to the transparent pixel electrode 15a.

With the resist film 19 left on the metal film 18, an amorphous silicon layer (n ⁺ -a-Si) 17b exposed on the surface is formed on the first B layer.
As shown in FIGS. (E) and (e), it is removed by etching. Then, when the resist film 19 is removed, as shown in FIGS. 1B (F) and (f), the transparent pixel electrodes 15a are arranged in a matrix on the upper surface of the transparent insulating substrate 10, and the transparent gate lines are formed. A transparent pixel electrode 1 in which a gate line 14b covered with a metal film 18 is formed on the film 14a
A TFT having an inverted staggered structure is formed corresponding to 5a in an electrically connected state.

According to such a method for manufacturing an active matrix liquid crystal display device, the transparent pixel electrodes 15a can be formed in a matrix on the transparent insulating substrate 10 by three photolithography processes, and the transparent pixels can be formed. Electrode 15a
Since a TFT having an inverted staggered structure corresponding to can be formed, the manufacturing process can be simplified, the productivity is excellent, and the manufacturing cost is low. Particularly, in the first step, the pixel electrode portion 15 composed of the ITO transparent conductive film 11 and the metal film 12 is formed, and in the subsequent steps, the gate insulating film 16 and the two-layer amorphous silicon film are formed by the plasma / CVD method.
Even if 17 is formed, the transparent conductive film 11 of the pixel electrode portion 15 is a metal film.
As it is protected by 12, transparent conductive film 11
Is reduced, the composition thereof is changed, and the resistance value, the transmittance, and the like are not lowered, and good production can be performed and high quality products can be obtained. Further, since the gate line 14b has the same metal film 18 as the drain electrode 20 and the source electrode 22 formed on the transparent electrode film 11,
Even if the gate line film 14a made of the transparent conductive film 11 is simply broken, the metal film 18 can prevent the entire gate line 14b from being broken, and the conduction reliability is excellent and the yield can be improved.

EFFECTS OF THE INVENTION As described in detail above, the present invention is the first step,
A transparent conductive film and a metal layer are laminated and formed on a transparent insulating substrate, and in a second step, pixel electrodes are formed in a matrix with a conductor composed of the transparent conductive film and the metal layer. A plurality of transistor element regions are formed by forming a conductive portion composed of an electrode portion and a line portion connected to the electrode portion between the portions, and forming an insulating film and an amorphous semiconductor film at a predetermined position on the conductor. And in the third step, at least the metal film laminated on the pixel electrode portion of the metal film is removed to form a transparent pixel electrode composed of only the transparent conductive film. Since the conductor film connected to the semiconductor film in the transistor element region is formed in a predetermined shape, the number of photolithography processes can be reduced to simplify the manufacturing process and reduce the cost. It is possible to obtain a good quality in the door.

[Brief description of drawings]

FIG. 1A and FIG. 1B show an embodiment of the present invention.
(A) to (E) of FIG. 1 and FIG. 1B are cross-sectional views of the main part showing the manufacturing process of the active matrix liquid crystal display device, and (a) to (e) of FIG. 1A and FIG. 2 (a) to 2 (e) are cross-sectional views of relevant parts showing a conventional manufacturing process. 10 ... Transparent insulating substrate, 11 ... Transparent conductive film, 12 ... Metal film, 13 ... Gate electrode, 14 ... Gate line section, 14a ...
… Gate line film, 14b …… Gate line, 15 …… Pixel electrode part, 15a …… Pixel electrode, 16 …… Gate insulating film, 17…
… Two layers of amorphous silicon film, 17a …… Active amorphous silicon film, 17b …… Amorphous silicon film, 1
8 …… Metal film, 20 …… Drain electrode, 22 …… Source electrode.

Claims (1)

[Claims] 1. A first step of laminating a transparent conductive film and a metal film on a transparent insulating substrate, and a conductor in which the transparent conductive film and the metal film are laminated,
The pixel electrode portion is formed in a matrix, a conductive portion including an electrode portion and a line portion connected to the electrode portion is formed between the pixel electrode portions, and an insulating film and an insulating film are formed at predetermined locations on the conductor. A second step of forming a plurality of transistor element regions by stacking an amorphous semiconductor film, and removing at least the metal film stacked in the pixel electrode portion among the metal films formed in the first step. Then, a third step of forming a transparent pixel electrode composed only of the transparent conductive film, and a conductor film connected to the semiconductor film of the transistor element region formed in the second step are formed into a predetermined shape. And a fourth step of forming the active matrix liquid crystal display device.