JPH06242453A - Active matrix type liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a structure which reduces the resistance of the source bus line of the active matrix type liquid crystal display device and also reduces the manufacturing cost by simplifying the process. CONSTITUTION:In the active matrix type liquid crystal display device which has pixel electrodes 104 arranged in matrix on an insulating substrate 101 and independently controls the pixel electrodes 104, and the source bus line 107 is formed of ITO, a contact hole 112 is formed in an area of an insulating film 103, formed on the source bus line 107, where it does not crosses the gate bus line 114, and while a gate electrode 113 gate bus line 114 is formed of molybdenum thereupon, the ITO and molybdenum are brought into contact with each other. This structure has the two-layered structure part of the ITO and molybdenum at part of the source bus line 107.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a gate bus line and a source bus line of an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art Pixel electrodes are arranged in a matrix on an insulating substrate, a thin film transistor element is connected to each pixel electrode, and the thin film transistor elements are switching-controlled so that each pixel electrode is independent of each other. It is used in display devices that use driven active matrix liquid crystals. Display devices adopting the active matrix drive system have been put to practical use in liquid crystal televisions, word processors, computer terminal display devices, and the like.

In these active matrix type liquid crystal display devices, FIG. 3A and FIG. 3 are a plan view of one pixel portion of an active matrix type liquid crystal display device using a stagger type thin film transistor and a sectional view at EF. It shows in (b). This active matrix type liquid crystal display device includes a light shielding plate 302 on a transparent insulating substrate 301, an insulating film 303, a pixel electrode 304 formed of a transparent electrode (ITO), a source electrode 305, and a drain electrode 306.
A first source bus line 307, an amorphous silicon layer 308 to be a channel, a first n ⁺ silicon semiconductor layer 309, and a second n ⁺ silicon semiconductor layer 310.
And a second source bus line 311 such as chromium for reducing the resistance of the source bus line, a gate insulating film 312 made of SiO ₂ , a gate electrode 313, and a gate bus line 314.

[0004]

In recent years, liquid crystal televisions, word processors, terminal display devices for computers, etc. in which active matrix type liquid crystal display devices have been put into practical use have been reduced in price, and active matrix type liquid crystal display devices themselves have been reduced in price. Price reduction is required, and simplification of the process is desired.

In the above conventional active matrix type liquid crystal display device, in order to reduce the resistance of the source bus line,
It is necessary to have a two-layer structure of a transparent conductive film (ITO) and metal wiring, which has a drawback that the process becomes complicated. When connecting ITO and metal wiring, chromium, which has a relatively high adhesive force on ITO, is often used as the metal wiring. However, chromium has a high specific resistance and is used in large-scale and high-definition active matrix liquid crystal display devices. Has the drawback of increasing the resistance of the source bus line, and further has the drawback of complicating the process because it is necessary to form metal wiring having a low specific resistance such as aluminum.

The present invention solves the above problems, and an object thereof is to provide an inexpensive active matrix type liquid crystal display device with a simplified process.

[0007]

The first invention of the present invention is as follows:
In an active matrix liquid crystal display device in which pixel electrodes are arranged in a matrix on an insulating substrate and staggered thin film transistors are used as switching elements for independently controlling the pixel electrodes, the gate electrodes and gate bus lines are made of molybdenum. The source bus line to I
A contact hole is formed in a region of the insulating film formed on the source bus line that does not intersect with the gate bus line, the ITO and the molybdenum are brought into contact with each other, and the ITO is partially formed on the source bus line. This is an active matrix type liquid crystal display device characterized in that a two-layer structure portion of molybdenum is arranged. In this liquid crystal display device, the gate electrode and the gate bus line and molybdenum electrically connected to the source bus line are simultaneously formed.

A second aspect of the present invention is an active matrix type liquid crystal in which pixel electrodes are arranged in a matrix on an insulating substrate and staggered thin film transistors are used as switching elements for independently controlling the pixel electrodes. In the display device, the gate electrode and the gate bus line are configured by a two-layer structure wiring in which the lower layer is molybdenum and the upper layer is aluminum, and the source bus line is formed of ITO,
A contact hole is formed in a region of the insulating film formed on the source bus line that does not intersect the gate bus line,
The active matrix type liquid crystal display device is characterized in that the ITO and the molybdenum are brought into contact with each other, and a three-layer structure portion of ITO and molybdenum-aluminum is arranged on a part of the source bus line.

[0009]

The gate bus line of the insulating film is formed on the source bus line formed of ITO by using the one-layer structure of molybdenum for the gate electrode and the gate bus line, or the two-layer structure wiring of molybdenum for the lower layer and aluminum for the upper layer. A large-scale high-definition active matrix that requires a low resistance source bus line by forming a contact hole in a region that does not intersect with and forming a gate electrode and a gate bus line at the same time as connecting ITO and molybdenum. Type liquid crystal display device can be manufactured at low cost by a simplified process.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a first embodiment, a plan view of an active matrix type liquid crystal display device is shown in FIG. 1 (a), and an AB sectional view thereof is shown in FIG. 1 (b), which will be described in detail below.

Chromium is formed on the glass substrate 101 by a sputtering method to a thickness of 500 Å, and a light shielding plate 102 is formed by a photolithography method. The light shielding plate 102 and the thin film transistor are formed on the entire upper surface of the light shielding plate 102. The insulating film 103 is formed to a thickness of 4500Å. Then I
A 600 Å TO film is formed, and the pixel electrode 104, the source electrode 105, and the drain electrode 106 are formed by photolithography.
And the first source bus line 107 is formed.

Next, the n ⁺ silicon film 500 Å is plasma C
The first n ⁺ silicon semiconductor layer 108 and the second n ⁺ silicon semiconductor layer 10 are formed by the VD method and etched.
9, the source electrode 105 is electrically connected to the first n ⁺ silicon semiconductor layer 108, and the drain electrode 106 is electrically connected to the second n ⁺ silicon semiconductor layer 109. Further, as the silicon semiconductor layer 110, amorphous silicon is formed into a film with a thickness of 300 Å by the plasma CVD method and is etched into a predetermined shape. A gate insulating film 111 made of silicon nitride is formed thereon by plasma CVD to a thickness of 3000 Å.

Next, a window is opened in the pixel electrode 104 portion of the gate insulating film 111 by etching.
A contact hole 112 is formed in a large part (at least 50% or more, preferably about 90%) of a region where the source bus line 107 and the gate bus line 114 do not intersect with each other, and molybdenum 3000 Å is formed thereon by a sputtering method. The molybdenum is etched to form the gate electrode 113, the gate bus line 114, and the second source bus line 115, and the first source bus line 1
07 is electrically connected to the second source bus line 115 through the contact hole 112.

The active matrix substrate manufactured in this manner is used as one cell substrate, and the substrate on which the counter electrodes (electrodes arranged to face each other in common for each pixel electrode) are formed is used as the other cell substrate. An active matrix type liquid crystal display device of the present embodiment can be obtained by interposing a liquid crystal layer in.

[0015]

[Embodiment 2] As a second embodiment, a plan view and a sectional view taken along the line CD of an active matrix type liquid crystal display device are shown in FIGS. 2 (a) and 2 (b), which will be described in detail below.

Chromium 500Å is formed on the glass substrate 201 by the sputtering method, and the light shielding plate 202 is formed in a predetermined shape by the photolithography method. A silicon oxide film having a thickness of 4500Å is formed on the light shielding plate 202 as an insulating film for insulating the thin film transistor. Then I
A TO film 600Å is formed and etched to form the pixel electrode 20.
4, the source electrode 205, the drain electrode 206, and the first source bus line 207 are formed.

Next, plasma C is applied to the n ⁺ silicon film 500Å.
The first n ⁺ silicon semiconductor layer 20 is formed by the VD method.
8 and the second n ⁺ silicon semiconductor layer 209, and the source electrode 205 and the first n ⁺ silicon semiconductor layer 2
08 is electrically connected to the drain electrode 206 and the second n
^{+ The} silicon semiconductor layer 209 is electrically connected. Further, amorphous silicon is formed as the silicon semiconductor layer 210 by 300Å plasma CVD method, and silicon nitride is formed as the gate insulating film 211 in 3000Å plasma C
The film is formed by the VD method.

Next, a window is opened in the pixel electrode 204 portion of the gate insulating film 211 by etching, and at the same time, the first electrode is formed.
A contact hole 212 is formed in a large part (at least 50% or more, preferably about 90%) of a region where the source bus line 207 and the gate bus line 215 do not intersect, and molybdenum 500Å and aluminum 20 are formed on the contact hole 212.
00Å is continuously formed by sputtering, and is collectively etched with a mixed acid of acetic acid, nitric acid, and phosphoric acid, and the first gate electrode 213, the second gate electrode 214, the gate bus line 215, the second source bus line 216, and The third source bus line 217 is formed, and the first source bus line 207 and the second source bus line 216 are electrically connected to each other through the contact hole 212.

By enclosing a liquid crystal layer between the active matrix substrate thus manufactured and the counter substrate on which the counter electrode is formed, the active matrix type liquid crystal display device of this embodiment can be obtained.

[0020]

According to the present invention, one layer of molybdenum is used for the gate electrode and the gate bus line, or molybdenum is used for the lower layer.
At the same time as forming the gate electrode and the gate bus line, a contact hole is formed in the insulating film in a region which does not intersect the gate bus line of the source bus line formed of ITO by using the two-layer structure wiring of aluminum as the upper layer. By connecting the metal wiring made of molybdenum and ITO, an active matrix type liquid crystal display device having a low resistance source bus line can be manufactured at a low cost in a simplified process.

[Brief description of drawings]

FIG. 1 is a plan view and an AB cross-sectional view of an active matrix type liquid crystal display device showing a first embodiment of the present invention.

FIG. 2 is a plan view and a CD sectional view of an active matrix type liquid crystal display device showing a second embodiment of the present invention.

FIG. 3 is a plan view and a cross-sectional view taken along line EF of a conventional active matrix liquid crystal display device.

[Explanation of symbols]

101, 201 glass substrate 102, 202 light shielding plate 103, 203 insulating film 104, 204 picture element electrode 105, 205 source electrode 106, 206 drain electrode 107, 207 first source bus line 108, 208 first n ⁺ silicon semiconductor Layers 109 and 209 Second n ⁺ silicon semiconductor layers 110 and 210 Silicon semiconductor layers 111 and 211 Gate insulating films 112 and 212 Contact holes 113 Gate electrodes 114 Gate bus lines 115 Second source bus lines 213 First gate electrodes 214 Second gate electrode 215 Gate bus line 216 Second source bus line 217 Third source bus line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Takahama 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Yukiya Nishioka 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Osaka Incorporated (72) Inventor Hidenori Otoko 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. An active matrix type liquid crystal display device in which pixel electrodes are arranged in a matrix on an insulating substrate and a staggered thin film transistor is used as a switching element for independently controlling the pixel electrodes. The line is made of molybdenum, the source bus line is formed of a transparent conductive film, and a contact hole is formed in a region of the insulating film deposited on the source bus line that does not intersect with the gate bus line to form the transparent conductive film. An active matrix type liquid crystal display device characterized in that the transparent conductive film and a two-layer structure portion of molybdenum are interposed in a part of the source bus line by bringing the molybdenum into contact. 2. An active matrix type liquid crystal display device in which pixel electrodes are arranged in a matrix on an insulating substrate and staggered thin film transistors are used as switching elements for independently controlling the pixel electrodes. The line is composed of a two-layer structure wiring in which the lower layer is molybdenum and the upper layer is aluminum, the source bus line is formed of a transparent conductive film, and the region of the insulating film formed on the source bus line that does not intersect the gate bus line is contacted. An active matrix type liquid crystal display characterized in that a hole is bored to bring the above-mentioned transparent conductive film into contact with the above-mentioned molybdenum, and the transparent conductive film and a three-layer structure portion of molybdenum and aluminum are interposed in part of the source bus line apparatus.