JPH05303111A - Active matrix substrate and its production - Google Patents

Abstract

(57) [Summary] (Modified) [Structure] The transparent conductive film 2 is formed on the substrate 1, and the transparent conductive film 2 is used as the base layer 2 for the pixel electrode 2a and the gate electrode 3a.
Then, the base layer 2b of the gate electrode is covered with a metal thin film 3 formed by electrolytic plating to form a gate electrode 3a, and then an insulating layer 4 to be a gate insulating film and a first layer to be a channel region. The semiconductor layer 5 and the second semiconductor layer 6 to be an ohmic contact layer are formed to form the first semiconductor layer 5 and the second semiconductor layer 6 in an island shape, and then the insulating layer on the pixel electrode 2a. A part of 4 is removed, and a metal layer 7 to be source / drain electrodes is formed and patterned. [Effect] The manufacturing process is simplified due to the reduction of the photo process. Also, mass productivity is increased by electrolytic plating of gate electrodes,
Further, since the gate electrode is formed of a metal material having a low resistance, the characteristics of the transistor are improved, and the display becomes high definition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an active matrix substrate and an active matrix substrate formed by the method, and more particularly to a method of manufacturing an active matrix substrate and an active matrix substrate used for an active matrix type liquid crystal display device or the like. Regarding

[0002]

2. Description of the Related Art A conventional method of manufacturing an active matrix substrate will be described with reference to FIG.

First, as shown in FIG. 1A, a transparent conductive film 2 to be a pixel electrode and a metal film 3 to be a gate electrode (scanning signal line) 3a are formed on a glass substrate 1 by a sputtering method or the like. To do.

Next, as shown in FIG. 1B, the metal film 3
Is patterned by etching or the like so that the gate electrode (scanning signal line) 3a is formed.

Next, as shown in FIG. 1C, the transparent conductive film 2 is patterned by etching or the like so that the lower layer portion 2a of the gate electrode 3a, the pixel electrode 2b and the extraction electrode 2c are formed.

Next, as shown in FIG. 3D, an insulating layer 4 which will be a gate insulating film, a first semiconductor layer 5 which will be a channel region, and a second semiconductor layer 6 which will be an ohmic contact layer will be sequentially formed. It is formed by stacking. The first semiconductor layer 5 is composed of a lower semiconductor layer 5a serving as a channel region and an upper semiconductor layer 5b serving as an etching stopper layer.

Next, as shown in FIG. 1E, the first semiconductor layers 5a and 5b and the second semiconductor layer 6 on the gate electrode 3a are formed in an island shape.

Next, as shown in FIG. 1F, a part of the insulating layer 4 on the pixel electrode 2b is removed.

Next, as shown in FIG.
Are formed and patterned to form the source / drain electrodes and divide the ohmic contact layer 6. In this case, the upper semiconductor layer 5b of the first semiconductor layer 5 serves as a stopper layer for the etching solution used when dividing the ohmic contact layer 6.
When forming and patterning the metal layer 7, the metal layer 7 on the extraction electrode 2c is left.

Finally, as shown in FIG. 1H, a passivation film 8 made of silicon nitride (SiN _x ) or the like is formed, and patterning is performed so that the extraction electrode 2c portion is exposed to complete the process.

[0011]

However, according to this conventional method for manufacturing an active matrix substrate, (b)
There is a problem that a photomask is required in each of the steps (c), (e), (f), (g), and (h), and a total of six photomasks are required, and the photoprocess takes time. If there are many photo process steps in this way, it becomes a factor of decreasing the manufacturing yield.

Further, in this conventional method of manufacturing an active matrix substrate, the metal layer 3 to be the gate electrode 3a is formed by a film forming method requiring a vacuum system such as spattering, so that mass productivity is poor. was there.

Further, in this conventional method of manufacturing an active matrix substrate, the metal layer 3 to be the gate electrode 3a is formed.
Is formed by a film-forming method that requires a vacuum system such as sputtering, the material is limited to chromium (Cr), aluminum (Al), tantalum (Ta), etc., in order to prevent signal delay. However, there is a problem that it is necessary to increase the width and thickness of the gate electrode 3a to reduce the resistance, which hinders high definition.

[0014]

The present invention has been made in view of the above problems of the prior art, and is characterized by the manufacturing method thereof in which a transparent conductive film is formed on a substrate. Then, the transparent conductive film is patterned into a base layer for the pixel electrode and the gate electrode, the base layer for the gate electrode is covered with a metal thin film formed by electrolytic plating to form a gate electrode, and then a gate insulating film is formed. An insulating layer, a first semiconductor layer to be a channel region, and a second semiconductor layer to be an ohmic contact layer are sequentially laminated to form a first semiconductor layer and a second semiconductor layer in an island shape. The point is that a part of the insulating layer on the pixel electrode is removed, and a metal layer to be the source / drain electrodes is formed and patterned.

If the above manufacturing method is used,
A pixel electrode made of a transparent conductive film, a gate electrode, and a take-out electrode are provided on a substrate, and the gate electrode is covered with a low-resistance metal material such as gold, silver, or copper, and an insulating film that becomes a gate insulating film is formed on the gate electrode. An active matrix substrate having a layer, a first semiconductor layer to be a channel region, a second semiconductor layer to be an ohmic contact layer, and a metal layer to be source / drain electrodes is obtained.

[0016]

With the above-described structure, the photo process for forming the gate electrode is reduced once compared with the conventional one, and the manufacturing process is simplified. Further, when the gate electrode is formed, electroplating is performed, so that mass productivity is increased. Further, when electrolytic plating is performed, the gate electrode can be formed of a metal material having a low resistance such as gold, silver, and copper, so that the on-state current of the transistor rises well and high definition can be achieved.

[0017]

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a diagram for explaining a manufacturing process of an active matrix substrate according to the present invention.

First, as shown in FIG. 1A, the transparent conductive film 2 is formed on the glass substrate 1 by a sputtering method or the like. This transparent conductive film 2 is made of indium tin oxide (IT
O) or tin oxide (SnO ₂ ).

Next, as shown in FIG. 3B, the transparent conductive film 2 is patterned so that the base layer 2a of the gate electrode, the pixel electrode 2b, and the extraction electrode 2c are formed. This patterning is performed by removing unnecessary portions by etching with an etching solution such as a mixed solution of hydroiodic acid and hypophosphorous acid.

Next, as shown in FIG. 3C, the underlayer 2b of the gate electrode is covered with a metal thin film formed by electrolytic plating. This metal material includes gold (Au) and silver (A
g), copper (Cu), etc. are suitable. For electrolytic plating of such metal materials, the pH is 3 for gold plating.
In the case of silver plating, for example, potassium cyanide potassium having a liquid temperature of 20 to 60 ° C. and a liquid temperature of 20 to 40 ° C. is used for silver plating. When plating, the pH is 11-13 and the liquid temperature is 50-6.
Copper cyanide or the like at 0 ° C. is used. Further, since the underlying layer 2a of the gate electrode serves as a scanning signal line of the active matrix substrate and is independent of the pixel electrode 2b, it may be connected to any one of the scanning signal lines. For example, only the base layer 2a and the extraction electrode 2c portion of the gate electrode can be selectively electrolytically plated.
Also, when copper or gold is used as the metal material, corrosion resistance
Titanium (Ti) or tantalum (Ta), which has excellent chemical resistance, may be further plated.

This is the same as the conventional manufacturing method, and as shown in FIG. 3D, the insulating layer 4 to be the gate insulating film, the first semiconductor layer 5 to be the channel region, and the ohmic contact layer are to be formed. The second semiconductor layer 6 is sequentially laminated and formed. The insulating layer 4 is, for example, a silicon nitride film (Si
N _X ), and the like, and the first semiconductor layer 5 and the second semiconductor layer 6 are formed of amorphous silicon or the like, and both are formed by a plasma CVD method or the like. When the first semiconductor layer 5 is formed of the lower semiconductor layer 5a that serves as a channel region and the upper semiconductor layer 5b that serves as an etching stopper layer, it is not necessary to provide the etching stopper layer in a special process, and the process is simplified. In addition, the channel length can be shortened and high definition can be achieved. In this case, in order to have a difference in etching rate between the upper semiconductor layer 5b and the second semiconductor layer 6, the upper semiconductor layer 5b contains, for example, a small amount of nitrogen element or carbon element, and the second semiconductor. It is desirable that the layer 6 be composed of a microcrystalline semiconductor layer.

Next, as shown in FIG. 3E, the first semiconductor layer 4 and the second semiconductor layer 5 on the gate electrode 3a are formed in an island shape. In this case, an etching solution such as hydrofluoric acid and nitric acid is used.

Next, as shown in FIG. 3F, a part of the insulating layer 4 on the pixel electrode 2a is removed. In this case, an etching solution such as a mixed solution of ammonium fluoride and hydrofluoric acid is used.

Next, as shown in FIG.
A metal layer 7 to be a drain electrode is formed and patterned. This metal layer 7 is made of aluminum, titanium, chrome,
It is made of tantalum. In this case, when etching aluminum or titanium, a mixed solution of phosphoric acid and nitric acid is used, when etching chromium, a mixed solution of cerium ammonium nitrate and nitric acid is used, and when etching tantalum, CF is used. Etching is performed by chemical dry etching using ₄ gas and O ₂ gas. The second semiconductor layer 6 is divided by etching with a mixed solution of hydrofluoric acid and nitric acid. In this case, the upper semiconductor layer 5b of the first semiconductor layer 5 serves as a stopper layer for the etching solution. A metal layer such as molybdenum silicide may be interposed between the ohmic contact layer 6 and the metal layer 7 in order to obtain a good ohmic contact between the ohmic contact layer 6 and the metal layer 7.

Finally, as shown in FIG. 3H, a passivation film 7 made of silicon nitride (SiN _x ) or the like is formed, and patterning is completed so that the extraction electrode 2c portion is exposed to complete the process. Such a passivation film 7
Is also formed by the plasma CVD method.

In the method of manufacturing an active matrix substrate according to the present invention, steps (b) (e) (f) (g) (h) are performed.
A photomask is required in each step of, and a total of five photomasks are sufficient.

[0028]

As described above, according to the method of manufacturing an active matrix substrate of the present invention, a transparent conductive film is formed on the substrate, and the transparent conductive film is patterned into pixel electrodes and gate electrodes. Since the gate electrode is covered with a metal thin film formed by electrolytic plating, the number of photo processes for forming the gate electrode is reduced once compared with the conventional method, the manufacturing process is simplified, and the factor of reduction in manufacturing yield is reduced. be able to. Further, when the gate electrode is formed, electroplating is performed, so that mass productivity is increased. Further, as described above, when the gate electrode is covered with a metal thin film formed by electrolytic plating, the gate electrode is covered with gold, silver,
It can be formed of a metal material having a low resistance such as copper, so that the on-state current of the transistor rises well and high definition can be achieved.

[0029]

[Brief description of drawings]

FIG. 1 is a process chart for explaining a method for manufacturing an active matrix substrate according to the present invention.

FIG. 2 is a process chart for explaining a conventional method of manufacturing an active matrix substrate.

[Simple explanation of symbols]

1 ... Substrate, 2 ... Transparent conductive film, 3a ... Gate electrode, 4 ... Insulating film, 5 ... First semiconductor layer, 6 ...
..Second semiconductor layer, 7 ... Metal layer

Claims (2)

[Claims] 1. A transparent conductive film is formed on a substrate, the transparent conductive film is patterned on a base layer of a pixel electrode and a gate electrode, and the base layer of the gate electrode is covered with a metal thin film formed by electrolytic plating. To form a gate electrode, and then an insulating layer to be a gate insulating film, a first semiconductor layer to be a channel region, and a second semiconductor layer to be an ohmic contact layer are sequentially laminated to form a first semiconductor layer and a first semiconductor layer. A method for manufacturing an active matrix substrate, comprising forming two semiconductor layers in an island shape, then removing a part of the insulating layer on the pixel electrode to form a metal layer to be a source / drain electrode and patterning the metal layer. 2. A pixel electrode made of a transparent conductive film, a gate electrode and a take-out electrode are provided on a substrate, and the gate electrode and the take-out electrode are covered with a low resistance metal material such as gold, silver or copper. An active matrix substrate comprising an insulating layer to be a gate insulating film, a first semiconductor layer to be a channel region, a second semiconductor layer to be an ohmic contact layer, and a metal layer to be source / drain electrodes, which are provided on the top.