JPH07162007A - Manufacturing method of active matrix substrate - Google Patents

Abstract

(57) [Abstract] [Purpose] To manufacture an active matrix substrate which can reduce power consumption of a liquid crystal display device at a low cost by a simplified process. [Configuration] Phosphorus ions are selectively implanted into a source electrode 105 and a drain electrode 106 made of ITO. By forming an a-Si film 107 thereon and diffusing phosphorus ions, the first n ⁺ a-Si is formed on the source electrode 105.
The contact layer 108 is formed in a self-aligned manner, and the second n ⁺ a-Si contact layer 109 is formed on the drain electrode 106.
Are formed in a self-aligned manner. Since phosphorus ions are not injected into the pixel electrode made of ITO, the transmittance of the pixel electrode does not decrease.

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 an active matrix substrate used in a liquid crystal display device or the like, in which a pixel electrode is independently controlled by a switching element for display.

[0002]

2. Description of the Related Art Conventionally, in a display device such as a liquid crystal display device, a display pattern is formed on a screen by selecting display picture elements arranged in a matrix and performing light modulation.
An active matrix driving method is known as one of the light modulation methods for the display picture element, and
It is used in word processors and terminal display devices of computers. In this active matrix drive type display device, an independent picture element electrode is provided for each display picture element, and a switching element is connected to each picture element electrode. By this switching element, the voltage applied between the pixel electrode provided on the active matrix substrate and the counter electrode provided on the counter substrate is switched, and the liquid crystal or the like sandwiched between the two substrates is switched. The display medium is light modulated. Here, as the switching element, a TFT (thin film transistor) element, a diode element, a FET (bulk transistor) element, a varistor element, etc. are generally known.

FIG. 2 shows a conventional active matrix substrate TF using a staggered TFT as a switching element.
A sectional view of a T portion is shown. In this active matrix substrate, a light shielding film 202 is formed on a glass substrate 201,
An insulating film 203 is formed so as to cover the light shielding film 202.
On the insulating film 203, a transparent conductive ITO (Ind
picture element electrode 20 made of ium tin oxide)
4, source electrode 205 and drain electrode 206 are formed. The source electrode 205 is connected to a source bus line (not shown), and the drain electrode 206 is formed in a state of being connected to the pixel electrode 204. First and second n ⁺ a-Si (amorphous silicon) contact layers 208 and 209 are formed on the source electrode 205 and the drain electrode 206, respectively.
An a-Si film 207 to be a channel of a TFT is formed in a state of being bridged over 08 and 209. a-Si
A gate electrode 211 is formed on the film 207 with a gate insulating film 210 interposed therebetween. Gate electrode 211
Are connected to a gate bus line (not shown).

[0004]

In the liquid crystal display device which has been put into practical use as the above-mentioned liquid crystal television, word processor, terminal display device of a computer, etc., the display quality is improved, the power consumption is reduced and the weight is reduced. It is necessary to achieve improved performance and lower prices. Therefore, there is a demand for development of a manufacturing method capable of obtaining a high-performance liquid crystal display device with a simplified process.

Conventionally, the above active matrix substrate is manufactured as follows.

First, as shown in FIG. 3A, a light shielding film 202 is formed on a glass substrate 201.

Next, as shown in FIG. 3B, the insulating film 2
03 is formed into a film, and the pixel electrode 204 and the source electrode 2 are formed thereon.
05 and the drain electrode 206 are formed.

After that, as shown in FIG. 3C, phosphorus ions are plasma-doped from the electrode forming side of the substrate.
As a result, the pixel electrode 204, the source electrode 205,
ITO such as drain electrode 206 and source bus line
Phosphorus ions are implanted into the entire surface of the pattern.

An a-Si film is formed thereon and phosphorus is diffused to form an n ⁺ a-Si layer. By patterning this, the n ⁺ a-Si contact layers 208 and 209 and the TFT as shown in FIG.
Then, an a-Si film 207 which will be the channel of is formed.

Next, as shown in FIG. 3E, a gate insulating film 210 is formed and a gate electrode 211 is formed thereon.

According to this method, the process can be simplified, but as shown in FIG.
04, the source electrode 205, the drain electrode 206, and the source bus line, etc., the entire surface of the pattern made of ITO is doped with phosphorus ions. As a result, there has been a problem that the transmittance of the pixel electrode 204 is lowered and the brightness of the liquid crystal display device is lowered. Further, in order to improve the brightness, it is necessary to increase the intensity of the backlight, which causes a problem that power consumption cannot be reduced.

The present invention has been made in order to solve the above-mentioned conventional problems, and can improve the performance of an active matrix type liquid crystal display device and can manufacture it by a simple process. It aims at providing the manufacturing method of.

[0013]

According to the method of manufacturing an active matrix substrate of the present invention, a thin film transistor for controlling a pixel electrode in which the pixel electrode is formed in a matrix is provided on each of the source electrode and the drain electrode. ^{+ an} a-Si contact layer is formed, an a-Si film is formed in a region extending from one contact layer to another contact layer, and a gate insulating film is interposed between the a-Si film and the a-Si film. A method of manufacturing an active matrix substrate having a structure in which a gate electrode is provided, and a step of forming the pixel electrode, the source electrode, and the drain electrode each made of a transparent conductive film on an insulating substrate. , A step of selectively implanting phosphorus ions into the source electrode and the drain electrode, and a-S covering the source electrode and the drain electrode into which the phosphorus ions are implanted. Film is formed by diffusing phosphorus into the a-Si film, since the n ⁺ a-Si contact layer and a step formed in a self-aligned manner, the objects can be achieved.

In this manufacturing method, after forming a light-shielding film on the insulating substrate, the source electrode and the drain electrode are formed above the light-shielding film, and then the source electrode and the drain electrode are formed. Forming a negative resist on the substrate and exposing and developing the negative resist from the light-shielding film side, thereby forming a resist pattern,
The phosphorus ions may be implanted from the resist pattern side.

[0015]

In the present invention, phosphorus ions are selectively implanted into the source and drain electrodes made of ITO. By forming an a-Si film thereon and diffusing phosphorus ions, an n ⁺ a-Si contact layer is formed in a self-aligned manner. Since phosphorus ions are not injected into the pixel electrode made of ITO, the transmittance of the pixel electrode does not decrease, the power consumption of the liquid crystal display device can be reduced, and a high-performance liquid crystal display with a simple process can be achieved. The device can be manufactured.

After forming a light shielding film on the insulating substrate, a source electrode and a drain electrode are formed above the light shielding film,
After that, a negative resist is formed on the substrate on which the source electrode and the drain electrode are formed, and the negative resist is exposed and developed from the light-shielding film side, whereby a resist pattern is formed and phosphorus ions are implanted from the resist pattern side. In this case, phosphorus ions are selectively implanted into the source electrode and the drain electrode.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1E shows a sectional view of a TFT portion of an active matrix substrate manufactured by using the present invention. In this active matrix substrate, a light shielding film 102 is formed on an insulating substrate 101 made of glass, and an insulating film 103 is formed so as to cover the light shielding film 102. On the insulating film 103, transparent and conductive ITO is used.
A pixel electrode 104, a source electrode 105, and a drain electrode 106 are formed. The source electrode 105 is connected to a source bus line (not shown), and the drain electrode 106 is formed in a state of being connected to the pixel electrode 104. Source electrode 105 and drain electrode 106
First and second n ⁺ a-Si (amorphous silicon) contact layers 108 and 109 are formed on the upper surface of the first and second contact layers 108 and 109. The film 107 is formed. A gate electrode 111 is formed on the a-Si film 107 with a gate insulating film 110 interposed therebetween. The gate electrode 111 is connected to a gate bus line (not shown).

This active matrix substrate was manufactured as follows.

First, as shown in FIG. 1A, a chromium film having a thickness of 500 angstrom is formed on an insulating substrate 101 by sputtering, and this is patterned to form a light shielding film 1.
02 was formed.

Next, as shown in FIG. 1B, the light shielding film 1
02 for insulating the thin film transistor from the thin film transistor 1
As No. 03, a silicon oxide film was formed to a thickness of 4500 angstroms. An ITO film is formed thereon with a thickness of 600 Å, and the ITO film is patterned to form a pixel electrode 104, a source electrode 105 and a drain electrode 106.
Formed.

Then, a negative resist is applied to the surface of the substrate on which the electrodes are formed (upper side in the figure), and the light-shielding film 102 is used as a mask to expose from the side opposite to the side on which the electrodes are formed (lower side in the figure).
By developing, as shown in FIG. 1C, a resist pattern 120 was formed in a self-aligned manner. Phosphorus ions were implanted from the resist pattern 120 side by, for example, an ion doping method. The implantation conditions at this time were an acceleration voltage of 10 kV and a dose amount of 2 × 10 ¹⁵ cm ^-2 . As a result, phosphorus ions are selectively implanted into the source electrode 105 and drain electrode 106 portions of the ITO pattern, but not into the source bus line or the pixel electrode 104 portion. As described above, when the light-shielding film 102 is used as a mast and the resist pattern 120 is formed, a separate light-shielding means such as a photomask is not required for forming the resist pattern 120, and the light-shielding means need not be aligned. ,
There is an advantage that the process can be simplified. However, it goes without saying that the present invention may form the resist pattern 120 without using the light shielding film 102 as a mask.

Next, an a-Si film 107 having a thickness of 600 angstrom was formed by plasma CVD method, and phosphorus was diffused. As a result, as shown in FIG. 1D, the first n ⁺ a-Si contact layer 108 is formed on the source electrode 105 in a self-aligned manner, and the drain electrode 10 is formed.
A second n ⁺ a-Si contact layer 109 is formed on the substrate 6 in a self-aligned manner. Then, the resist is removed.

Next, as shown in FIG. 1E, for example, a silicon nitride film having a thickness of 300 is used as the gate insulating film 110.
The film was formed to 0 angstrom. A molybdenum film having a thickness of 3000 angstrom was formed thereon by, for example, sputtering, and this was patterned to form a gate electrode 111, which was used as an active matrix substrate.

When the active matrix substrate and the counter substrate having the counter electrode formed thereon are bonded to each other and liquid crystal is injected into the gap between them, a liquid crystal panel is produced. We were able to reduce power consumption.

[0026]

As is apparent from the above description, according to the present invention, since phosphorus ions are selectively implanted into the ITO patterns of the source electrode and the drain electrode, n ⁺ a-
The Si contact layer can be formed in a self-aligned manner. At this time, by forming the resist pattern by using the light shielding film as a mask, the active matrix substrate can be manufactured at a low cost by a simplified process. Since phosphorus ions are not implanted into the ITO pattern of the picture element electrode, the transmittance of the picture element electrode does not decrease, and the power consumption of the liquid crystal display device can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method for manufacturing an active matrix substrate which is an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional active matrix substrate.

FIG. 3 is a cross-sectional view showing a manufacturing process of a conventional active matrix substrate.

[Explanation of symbols]

101 glass substrate 102 light-shielding film 103 insulating film 104 picture element electrode 105 source electrode 106 drain electrode 107 a-Si film 108 first n ⁺ a-Si contact layer 109 second n ⁺ a-Si contact layer 110 gate insulating film 111 gate electrode 120 resist pattern

Claims (2)

[Claims] 1. A thin film transistor for controlling a pixel electrode in which the pixel electrode is formed in a matrix, wherein an n ⁺ amorphous silicon contact layer is formed on each of the source electrode and the drain electrode, and one of the contact layers is formed. To the other contact layer, an amorphous silicon film is formed on the contact layer, and a gate electrode is provided on the amorphous silicon film with a gate insulating film interposed therebetween. A step of forming the pixel electrode, the source electrode, and the drain electrode each made of a transparent conductive film on an insulating substrate; and a step of selectively implanting phosphorus ions into the source electrode and the drain electrode. Amorphous silicon film is formed to cover the source and drain electrodes implanted with phosphorus ions. By diffusing phosphorus into the amorphous silicon film, the production method of the active matrix substrate and forming a n ⁺ amorphous silicon contact layer in a self-aligned manner. 2. A light-shielding film is formed on the insulating substrate, the source electrode and the drain electrode are formed above the light-shielding film, and then on the substrate on which the source electrode and the drain electrode are formed. The active matrix substrate according to claim 1, wherein a negative resist is formed on the substrate, the negative resist is exposed from the light-shielding film side and developed to form a resist pattern, and the phosphorus ions are implanted from the resist pattern side. Production method.