JPH0713194A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To provide the process for production of the liquid crystal display element capable of simplifying production stages and the constitution to be used for production, shortening the time for production and increasing a non- defective article rate by providing the liquid crystal display device which can be improved in an opening rate and improved in a display grade. CONSTITUTION:A display substrate 42 includes an insulating substrate 21, such as glass, and a substrate protective film 22 is formed on this insulating substrate 21. Gate electrode lines 23 and a first gate insulating film 24 are formed on this substrate protective film 22. A second substrate protective film 25, a semiconductor film 26, contact layers 28a, 28b, a channel part protective insulating film 27, source electrodes 29 and drain electrodes 30 respectively formed on the contact layers 28a, 28b, pixel electrodes 31 and a protective insulating film 32 are formed, successively from the insulating substrate 21 side, in this order on the protective insulating film 22. Opening regions of nearly the same shape and the same size as the shape and size of the pixel electrodes 31 are formed in the protective insulating film 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix type liquid crystal display substrate, and more particularly to a matrix type liquid crystal display substrate for performing a matrix display using a transistor as an address element and a method for manufacturing the same.

[0002]

2. Description of the Related Art A liquid crystal display device is constructed by sandwiching a liquid crystal layer between a pair of insulating substrates such as glass. In an active matrix display device, a thin film transistor or the like is formed as a switching element on one display substrate of a pair of insulating substrates, and a counter electrode is formed on the other counter substrate of the pair of insulating substrates. Has been done.

A plan view of the display substrate in a conventional matrix type liquid crystal display device is shown in FIG. This display board
The insulating substrate 1 and the substrate protection film 2 formed on the insulating substrate 1, the thin film transistors 13 formed in a matrix, the pixel electrodes 11, and the gate electrode lines (scanning lines).
3 and a source electrode line (signal line) 9.

The gate electrode line 3 and the source electrode line 9 are arranged so as to intersect with each other through the insulating films 2 and 5 so as not to be electrically short-circuited. A transparent pixel electrode 11 is formed in a region surrounded by the signal lines 3 and 9, and is connected to the source electrode line 9 via a thin film transistor 13.

Then, in the peripheral portion of the picture element electrode 11,
As the protective insulating film 12, Si _x N _y is relatively easily formed by the plasma CVD method in a low temperature atmosphere. In consideration of the influence of the pattern shift when forming the Si _x N _y , the pixel electrode 11 is patterned so as to cover a portion slightly inward of the peripheral portion thereof. The hatched portion in FIG. 4 indicates the opening region 14 where the protective insulating film 12 is not formed and the pixel electrode 11 is exposed.

FIG. 6 is a cross-sectional view of the thin film transistor 13 formed on the display substrate, taken along the section line X6-X6 in FIG.

A substrate protective film 2 is formed on an insulating substrate 1, and a gate electrode 3, a first gate insulating film 4, a second gate insulating film 5 and a semiconductor for forming a channel portion are formed on the substrate protective film 2. Film (consisting of intrinsic semiconductor, amorphous silicon or microcrystalline silicon) 6, channel portion protective insulating film 7, n-type or p-type semiconductor formed on the protective film 7, amorphous silicon film or microcrystalline silicon Contact layers 8a, 8b made of a film, contact layers 8a,
The source electrode 9 and the drain electrode 10 and the pixel electrode 11 respectively formed on 8b are formed in this order on the insulating substrate 1, and the protective insulating film 12 is formed on the uppermost layer.

In the above display substrate, a thin film having a uniform film thickness is formed on the entire surface of the insulating substrate 1 on the insulating substrate 1.
It is created by repeating the step of performing pattern processing several times.

The pattern processing method will be described below.

A photoresist is applied to the entire surface of the insulating substrate 1 on which any thin film such as a metal thin film on which the gate electrode 3 is formed and an insulating thin film on which the gate insulating film 4 is formed. The photomask on which each pattern such as the gate electrode 3 is formed is accurately positioned with respect to the insulating substrate 1. Exposing with a stepper device.
In the subsequent phenomenon step, a pattern of photoresist is formed on the thin film. Hereinafter, the process from the application of the photoresist to the phenomenon will be referred to as a photolithography process. When this insulating substrate 1 is dipped in an etching solution, the thin film portion not covered with the photoresist is melted and removed, and the thin film pattern is formed. Finally, the remaining resist is removed by peeling or the like.

[0011]

The display substrate is made finer by forming the pixel electrodes 11 at a high density. On the other hand, as the definition becomes higher, the areas of regions such as the gate signal line 3, the source signal line 9 and the thin film transistor 13 that do not contribute to the image display operation relatively increase. Therefore, there is a problem that the aperture ratio, which is the ratio of the area of all the pixel electrodes 11 to the area of the display area defined on the display substrate, decreases.

As described above, the protective insulating film 12 and the second-order light amount 14 are formed by the transparent insulating film 12 (for example, Si _x N _y ) which is generally transparent and conductive when the protective insulating film 12 is present on the pixel electrode 11. This is because the interface between the pixel electrode 11 using the film ITO and the protective insulating film 12 exhibits current rectification characteristics, and a DC component that adversely affects liquid crystal driving is generated.

In order to effectively utilize the picture element such as increasing the aperture ratio, it is necessary to use the picture element electrode 11 so as to maximize the area of the picture element. On the other hand, therefore, in the prior art, as shown in FIG. 5, the protective insulating film 12 covers the portion of the pixel electrode 11 slightly inward of the peripheral edge of the pixel electrode 11, and further inside thereof. At this point, pattern processing is performed so that the opening region 14 is formed. As a result, a margin for a pattern shift when the protective insulating film 12 is formed is determined. Since the margin is set in this way, the alignment of the liquid crystal is likely to be disturbed due to the step at the boundary between the pixel electrode 11 and the protective insulating film 12. Therefore, there is a problem in that display unevenness occurs near the boundary and the display quality is degraded.

Therefore, in an actual liquid crystal display device, a black matrix made of a material having a light-shielding property is used in a shape that covers a step portion at the boundary between the pixel electrode 11 and the protective insulating film 12. The black matrix covers a region slightly inward of the peripheral edge of the pixel electrode 11 and shields the vicinity of the boundary so that the vicinity of the boundary does not contribute to the display.

The existence of such a black matrix is
The effective area in which the liquid crystal operates in the pixel electrode 11 is reduced. As a result, the aperture ratio is further reduced. In order to increase the aperture ratio, it is necessary to pattern the opening region 14 of the protective insulating film 12 over the entire surface of the pixel electrode 11. For such pattern processing, a highly accurate exposure device is required.

Further, a large number of steps are required to form a thin film transistor. This increases the probability of producing a defective thin film transistor, and also increases the manufacturing time and the manufacturing cost.

The present invention has been made to solve the above problems, and an object thereof is to provide a liquid crystal display device capable of increasing the aperture ratio and improving the display quality. It is an object of the present invention to provide a method for manufacturing a liquid crystal display device, which can simplify the manufacturing process and the structure used for manufacturing, shorten the manufacturing time, and increase the yield rate.

[0018]

A liquid crystal display device of the present invention includes a substrate having a light-transmitting property, a control signal line and a display signal line formed on the substrate and made of a material having a light-shielding property,
The protective insulating film formed only on the non-display portion including the control signal line and the display signal line is provided, thereby achieving the above object.

A method of manufacturing a liquid crystal display device according to the present invention comprises a step of forming a control signal line and a display signal line made of a material having a light shielding property on a substrate having a light transmitting property, and a photosensitive resin on the substrate. The step of forming a material and irradiating the substrate with light from the side opposite to the side where the control line and the display signal line are formed, and using the control signal line and the display signal line as a light-shielding mask, And a step of exposing the functional resin material to light, whereby the above object is achieved.

[0020]

According to the present invention, by the above means, the protective insulating film can be formed only on the non-display portion including the control signal line and the display signal line without displacement. As a result, the region surrounded by the control signal line and the display signal line can contribute to the display over the entire area. Therefore, the aperture ratio of the liquid crystal display device can be significantly improved.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of the display substrate 42 for explaining the structure of the thin film transistor 43 formed on the display substrate 42 of the matrix type liquid crystal display device 41 of the present embodiment, and FIG. 2 is a sectional plane line X2 of FIG. It is sectional drawing seen from -X2.

The active matrix liquid crystal display device 41 will be described in the following embodiments, but the present invention is not limited to the structural examples and manufacturing method examples in the present embodiments. The liquid crystal display device 41 is configured by sandwiching a liquid crystal layer between a pair of insulating substrates such as glass. In an active matrix display device, a pixel electrode, a thin film transistor, or the like is formed on one display substrate 42 of a pair of insulating substrates, and a counter electrode is formed on the other counter substrate of the pair of insulating substrates. Are formed.

The display substrate 42 includes an insulating substrate 21 such as glass, and a substrate protective film 22 is formed on the insulating substrate 1. A gate electrode line 23 and a first gate insulating film 24 are formed on the substrate protection film 22. On the gate insulating film 24, a second gate insulating film 25, a semiconductor film 26 forming a channel portion and formed of an intrinsic semiconductor film, an amorphous silicon film, a microcrystalline film, or the like, an n-type or a p-type Contact layers 28a and 28b formed of a semiconductor film (which may be an amorphous silicon film, a microcrystalline film, or the like), a channel portion protective insulating film 27,
The source electrode 29, the drain electrode 30, and the pixel electrode 3 which are respectively formed on the contact layers 28a and 28b.
1 and the protective insulating film 32 are formed in this order from the insulating substrate 21 side. In the protective insulating film 32, an opening region 34 having substantially the same shape and size as the pixel electrode 31 is formed.
Are formed. The gate electrode line 23, the gate insulating films 24 and 25, the semiconductor film 26, the contact layers 28a and 2
The thin film transistor 43 is formed by including 8b, the channel portion protective insulating film 27, the source electrode 29, and the drain electrode 30.

FIG. 3 is a process chart for explaining the manufacturing process of the liquid crystal display device of this embodiment. A method of manufacturing the liquid crystal display device of the above embodiment will be described with reference to FIG.

In step a1, a substrate protective film 22 made of tantalum pentoxide having a film thickness t1 (50 as an example) is formed on a transparent insulating substrate 21 made of glass by a sputtering method.
0 nm). In step a2, the substrate protective film 2
2 on top of which tantalum is formed into a film thickness t2 by a sputtering method.
(400 nm as an example) is deposited. This tantalum is a material that does not transmit light. After the tantalum is deposited, the gate electrode line 23 is formed by photoetching. Process a
3, the surface of the gate electrode line 23 is oxidized by anodic oxidation, and tantalum pentoxide is deposited to a film thickness t3 (300 as an example).
nm) to form the first gate insulating film 24.

In step a4, the gate insulating film 24 is formed.
Then, a nitride film which is the second gate insulating film 25 is formed on the upper surface of the film by a plasma CVD method to a film thickness t4 (300 nm as an example)
And in step a5, an i-type a-Si film to be the semiconductor film 26 is formed to a film thickness t5 (30 nm as an example),
In step a6, a nitride film to be the channel protective insulating film 27 is formed to a film thickness t6 (200 nm as an example). The gate insulating film 25, the semiconductor film 26, and the channel portion protective film 27 are continuously deposited using a plasma CVD device.

Next, in step a7, the insulating substrate 21
A photoresist is applied over the entire surface. Next, the photoresist is patterned into a mask by a photo etching technique. In step a8, using this photoresist mask, Si _x having a thickness of 200 nm is formed.
The N _y film is etched with the pattern of the mask to form the channel portion protective insulating film 27.

Next, in step a9, plasma CVD is performed.
N is used to form the contact portions 8a and 8b using the apparatus.
_{A +} -type a-Si film is deposited to a film thickness t7 (30 nm as an example). This n ₊ -type a-Si film is patterned together with the n-type a-Si film and the i-type a-Si film by a photoetching technique, and the i-type a-Si film becomes the semiconductor film 26 and becomes the n ₊ -type a-Si film. The -Si film becomes contact layers 28a and 28b.

The semiconductor film 26 and the contact layer 28
The above manufacturing method can be applied even if a and 28b are each formed of a microcrystalline silicon film.

Further, in step a10, Ti, Mo, W is formed by a sputtering method or an electron beam evaporation method.
As an example, a metal film such as
Pattern with photo-etching technology. This allows
Source and drain electrodes 29, 30 are formed. In this step, the thin film transistor 43 is constructed.
Next, by the same sputtering method or electron beam evaporation method, a transparent conductive film containing indium oxide as a main component is deposited to a film thickness t8 of 100 nm as an example. The transparent conductive film is patterned by the photoetching technique to form the pixel electrode 11 for display.

Next, the protective insulating film 32 is formed. First,
In step a12, on the entire surface of the insulating substrate 21,
By the plasma CVD method, a Si _x N _y film is used as an example,
It is deposited to a film thickness t9 of 0 nm. In step a13, the insulating substrate 21 is coated with a photoresist using a spin coater. Then, in step a14,
As described above, with the gate electrode line 23 and the source electrode 29 formed of the light-shielding material as a mask, the insulating substrate 21 is exposed from the back surface on the side opposite to the surface on which the gate electrode line 23 and the like are formed. The back surface is exposed by irradiating light such as ultraviolet rays for curing the resist.

In step a15, the photoresist after exposure is subjected to a phenomenon to remove the unexposed portion as an example. Next, the insulating substrate 21 is dipped in an etching solution to etch the exposed portion of the Si _x N _y film in the opening of the photoresist to form a pattern. As a result, in the protective insulating film 32, the opening region 34 having substantially the same shape and the same size as the pixel electrode 31 could be formed.

An example of the plan view dimensions of one picture element portion of the liquid crystal display device of this embodiment is shown in the plan view of FIG. Gate electrode wire 2
3 has a line width W1 of 50 μm, and the source electrode line 29 has a line width W2.
Is 10 μm, and the distance L1 between the gate electrode lines 23 is 200 μm
m, the distance L2 between each source electrode line 29 was 100 μm, and the width W3 from each electrode such as the gate electrode line 23 and the source electrode line 29 to the pixel electrode 31 was 5 μm.

In the liquid crystal display device of the present embodiment and the manufacturing method thereof as described above, the following effects are achieved.

(1) In the conventional case, the pattern of the protective insulating film 12 includes the above-mentioned margin, so that the opening region 14 of the protective insulating film 12 is smaller than the dimension of the pixel electrode 11, The peripheral portion of the protective insulating film 12 was located at a position 3 μm from the end of the element electrode 11. Therefore, the effective area that contributes to the display of the pixel electrode 11 was small by the amount of the margin. According to the measurement by the inventor of the present application, when the occupied area of the conventional thin film transistor 13 and the thin film transistor 43 of the present embodiment is 1000 μm ² , for example,
The effective area in the conventional structure is 14456 μm ² , and the effective area in the fairness of this embodiment is 1610.
It was 0 μm ² . Therefore, it can be confirmed that the effective area of the pixel electrode 31 for operating the liquid crystal in this embodiment is about 10.2% larger than that of the conventional one, and the aperture ratio is improved.

(2) In the pattern formation of the protective insulating film 32 of the liquid crystal display substrate, after applying a photoresist, the gate electrode line 23, the source electrode line 29 and the drain electrode 30 having a light shielding property are used as a light shielding mask for insulation. Board 2
The photoresist is exposed by irradiating ultraviolet rays from the back surface of No. 1. As a result, the protective insulating film 32 is patterned without using a separate mask used in the photolithography technique as in the conventional technique.
As a result, the manufacturing process and the number of parts used for the manufacturing process can be simplified.

(3) In the present embodiment, the protective insulating film 32
A high-precision stepper device is not required for patterning. Therefore, since it is not necessary to pass through the stepper device, the exposure time is less than half that of the conventional case. Also, you don't have to use a photomask. As a result, the manufacturing time is shortened and the labor required for manufacturing is also reduced.

(4) Since the gate electrode line 23 and the source electrode line 29 are used as a light-shielding mask when forming the pattern of the protective insulating film 32, the pattern for the pixel electrode 31 in the opening region 34 formed in the protective insulating film 32. I was able to eliminate the gap. This improves the non-defective rate.

(5) Even if the type of the insulating substrate 21 used in the liquid crystal display device is changed, it is not necessary to prepare a new photomask for a photo process on the insulating substrate of a new type. Also in this respect, the labor required for manufacturing the liquid crystal display device can be reduced.

(6) In this embodiment, as described above, the opening region 34 in the protective insulating film 32 can be formed to have substantially the same shape and the same size as the pixel electrode 31. As a result, the pixel electrode 31 can contribute to the display in its entire area. Thereby, the aperture ratio of the liquid crystal display device can be increased and the display quality can be improved.

[0041]

As described above, according to the present invention, the protective insulating film can be formed only on the non-display portion including the control signal line and the display signal line without displacement. As a result, the region surrounded by the control signal line and the display signal line can contribute to the display over the entire area. Therefore, the aperture ratio of the liquid crystal display device can be remarkably improved, and the display quality can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a plan view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the section line X2-X2 in FIG.

FIG. 3 is a process diagram illustrating a manufacturing process of a liquid crystal display device according to an embodiment of the present invention.

FIG. 4 is a plan view of one picture element portion of the liquid crystal display device of the present embodiment.

FIG. 5 is a plan view of a conventional liquid crystal display substrate.

6 is a cross-sectional view taken along the section line X6-X6 in FIG.

[Explanation of symbols]

 23 Gate Electrode Line 26 Semiconductor Films 28a, 28b Contact Layer 29 Source Electrode 30 Drain Electrode 31 Pixel Electrode 32 Protective Insulating Film 34 Opening Area

Claims (2)

[Claims] 1. A light-transmitting substrate, a control signal line and a display signal line formed on the substrate and made of a light-shielding material, and a non-display portion including the control signal line and the display signal line. A liquid crystal display substrate including a protective insulating film formed only on the upper surface of the liquid crystal display substrate. 2. A step of forming a control signal line and a display signal line made of a light-shielding material on a light-transmitting substrate, a step of forming a photosensitive resin material on the substrate, and the substrate. With respect to the above, a step of irradiating light from the side opposite to the side where the control line and the display signal line are formed and exposing the photosensitive resin material by using the control signal line and the display signal line as a light-shielding mask. A method of manufacturing a liquid crystal display substrate including.