JP2001281680A - Liquid crystal display device, method of manufacture for the same and film-laminated structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flatly form a pixel electrode, not only between wirings but also on the wirings to improve an opening ratio in an active matrix type liquid crystal display device. SOLUTION: An insulating film pattern 4 having a recessed part 4a is formed, and the wiring 2 is formed in the recessed part 4a. The depth of the recessed part 4a is equal to the film thickness of the wiring 2. An upper part insulating film 5, having a continuous surface, is formed on the entire surface over the insulating film pattern 4 and the wiring 2 in the recessed part, and a pixel electrode 3 is formed on the upper part insulating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device and a method of manufacturing the same, and more particularly, to a technique for flattening the surface of a wiring region and an inter-wiring region in a driving substrate for such a liquid crystal display device. .

[0002]

2. Description of the Related Art FIGS. 7A and 7B schematically show a plan view and a sectional view of a main part of a drive substrate in a conventional active matrix type liquid crystal display device. In addition, FIG.
(B) schematically shows a plan view and a sectional view of a main part of a drive substrate in another conventional active matrix type liquid crystal display device. In these drawings, similar parts are denoted by the same reference numerals.

The structure of the conventional driving substrate shown in FIG. 7 corresponds to that disclosed in Japanese Patent Application Laid-Open No. Hei 4-234820, wherein 12 is a wiring, 13 is a pixel electrode, 14 is an insulating film, and 16 is This is a substrate including an insulating film substrate 16a and a lower layer 16b formed on the insulating film substrate. This drive substrate forms a layer and a pattern (lower layer 16b) other than the wiring 12 and the pixel electrode 13 on the insulating substrate 16a, then forms an insulating film 14, and subsequently forms the pixel electrode 13 on the insulating film 14. In addition, the wiring 12 is formed. If the liquid crystal display device is of a transmission type, a transparent material must be used for the insulating film 14, and therefore, for example, photosensitive transparent polyimide is used.

On the other hand, the structure of the conventional driving substrate shown in FIG. 8 is based on the technology disclosed in Japanese Patent Application Laid-Open No. 4-338718. According to this conventional technique, in order to make the upper surface of the wiring 12 and the pixel electrode 13 flat, that is, at the same level, a transparent insulating film 14 is laid under the pixel electrode 13 to form a convex portion, or the wiring is etched in advance to form a concave portion. To next,
By covering the wiring 12 with the insulator 15, the transparent pixel electrode 13
To eliminate the step. As the insulator 15, for example, a polyimide resin film is used.

[0005]

In the above two prior arts, the wiring 12 (FIG. 7) or the wiring 12 (FIG. 8) covered with the insulator 15 and the insulating film 14 form a continuous same level surface. Therefore, the region where the pixel electrode 13 can be formed is limited on the insulating film 14. Here, the pixel electrode 1
In order to explain the reason why the region in which the pixel electrode 3 can be formed is limited on the insulating film 14, the pixel electrode forming region is formed not only on the insulating film 14 but also on the wiring 1 in each of the conventional structures of FIGS.
FIGS. 9 and 10 show the case where the area is extended to the area 2 above. In FIG. 9, since the wiring 12 and the pixel electrode 14 are directly connected, the pixel is always electrically connected to the wiring 12. 9 and 10, the pixel electrode 1
3 is affected by the wiring step and is not flat (recess)
Will occur. Therefore, in the rubbing step of performing the alignment treatment of the liquid crystal, the alignment treatment cannot be performed uniformly due to the obstacle of the step, so that the alignment force of the liquid crystal is reduced at the step. For the above reasons, the pixel electrode 13 cannot be formed in a region other than the insulating film 14 in the conventional structure. This leads to a decrease in aperture ratio, which is inconvenient for a liquid crystal display device.

Accordingly, an object of the present invention is to provide an active matrix type liquid crystal display device in which a plurality of scanning lines and a plurality of signal lines intersect on an insulating substrate, and a pixel electrode is provided on at least one of the scanning lines and the signal lines. It is an object of the present invention to provide a liquid crystal display device capable of improving the aperture ratio by making the device flat, and a method of manufacturing the same. Another object of the present invention is to provide a film stack structure suitable for realizing such a liquid crystal display device.

[0007]

In order to achieve the above object, a liquid crystal display device according to the present invention is an active matrix type liquid crystal display device in which a plurality of scanning lines and signal lines intersect on an insulating substrate. At least one of the signal wirings is formed in a concave portion provided in the insulating film pattern, and an upper insulating film having a continuous surface is formed on the insulating film pattern and the wiring in the concave portion. It is characterized by having.

According to this structure, since the wiring is formed in the concave portion of the insulating film pattern, the thickness of the wiring is absorbed by the depth of the concave portion. Therefore, the surface of the upper conductive film continuously formed on the wiring and the insulating film pattern can have good flatness over substantially the entire surface. Therefore, when a pixel electrode is formed on this upper insulating film, the entire surface of the pixel electrode can also have good flatness. That is, a planarized structure is obtained in all regions on and between the wirings. Therefore, uniform alignment processing can be performed. Further, since the upper insulating film formed on the wiring and between the wirings has a continuous flat surface, the pixel electrode formation region can be extended not only between the wirings but also on the wirings. Therefore,
The aperture ratio can be improved.

When the present invention is applied to only one of the scanning wiring and the signal wiring, it is desirable to apply the present invention to the wiring arranged on the upper side, usually to the signal wiring. In this case, the step formed by the lower wiring thickness can be effectively reduced.

The liquid crystal display device may be, for example, a method of manufacturing a liquid crystal display device according to another aspect of the present invention, that is, a step of forming an insulating film pattern, a step of forming a recess in the insulating film pattern, Forming a wiring of one of a scanning wiring and a signal wiring in the recess, and forming an upper insulating film having a continuous surface on the insulating film pattern and the wiring. Can be manufactured by

In order to ensure that the upper insulating film fills the gap between the surface defining the recess of the insulating film pattern and the side surface of the wiring facing this surface, the upper insulating film defines the recess. It is preferable that the film is formed so as to have a film thickness that is at least half the space between the surface of the insulating film pattern and the side surface of the wiring facing the surface. The upper insulating film having such a thickness may be used as it is, or may be thinned by an etch-back method. By etching back the entire upper insulating film, an upper insulating film having an arbitrary thickness can be obtained. Further, the flatness is further improved.

When the present invention is applied to a transmission type liquid crystal display device, the insulating film pattern has a refractive index of 1.4 to 1.4.
It is preferable to use a transparent film such as a 1.95 oxide film.

In one embodiment, a contact hole extending from the bottom of the concave portion to a lower layer is formed in the insulating film pattern.

In order to manufacture a liquid crystal display device having such a structure, the manufacturing method of the present invention further comprises forming a recess in the insulating film pattern, and then extending the contact extending from the bottom of the recess to a lower layer. The method further includes the step of forming a hole, wherein in the step of forming the wiring, the same conductive material as the wiring is buried in the contact hole simultaneously with the formation of the wiring.

Further, the film laminated structure of the present invention comprises a first insulating film having a concave portion, a conductive film provided in the concave portion and having a thickness substantially equal to the depth of the concave portion, And a second insulating film having a substantially constant thickness formed on the conductive film and the conductive film.

In this film laminated structure, the upper surface of the first insulating film and the upper surface of the conductive film are substantially at the same level, so that the second insulating film formed thereon has a flat surface over the entire surface. Can be provided. This film stacking structure can be used not only for signal wiring or scanning wiring in an active matrix type liquid crystal display device but also for any conductive film / insulating film stacking position as long as a flat surface structure is desired. it can.

[0017]

FIG. 3 is a simplified partial plan view of a driving substrate constituting a transmission type active matrix liquid crystal display device according to an embodiment of the present invention, and FIG. 1 is a method for manufacturing the driving substrate of FIG. FIG. 1E is a cross-sectional view taken along a line 1E-1E in FIG. Note that, in one aspect, the present invention has a feature in that a pixel electrode formation region is enlarged by flattening a wiring region and an inter-wiring region. Therefore, in these drawings, only a portion related to the invention is shown. Portions that are not directly related to the present invention, such as liquid crystals and alignment films, are omitted from the drawings to simplify the drawings.

As shown in FIG. 3, a large number of scanning lines (only two adjacent lines) 1 extend in the row direction in parallel with each other, and a large number of parallel signal lines (only two adjacent lines are shown) 2.
Extend in the column direction above the scanning lines 1 so as to be orthogonal to the scanning lines 1, and near each intersection of the scanning lines 1 and the signal lines 2, a thin film transistor (TFT) as a switching element (not shown) is provided. Is formed.
The gate electrode of the TFT is connected to the scanning wiring 1, the source electrode is connected to the signal wiring 2, and the drain electrode is connected to the substantially rectangular pixel electrode 3. Each of the scanning wirings 1 and each of the signal wirings 2 are accommodated in a recess 4 a of the corresponding insulating film pattern 4. An upper insulating film 5 functioning as a flattening film is formed on each of the wirings 1 and 2 and the insulating film pattern 4 and between each of the wirings 1 and 2 and each insulating film pattern 4. On the upper insulating film 5 formed on the signal wiring 2, the pixel electrode 3 extends in a state where the peripheral portion is overlapped with one of the adjacent scanning wirings 1 and one of the adjacent signal wirings 2. .

Next, referring to FIG. 1, the method of manufacturing the liquid crystal display device according to the first embodiment will be focused on the process of manufacturing a drive substrate, particularly the process from formation of an insulating film pattern to formation of a pixel electrode. Will be explained.

First, as shown in FIG. 1A, an insulating film (first insulating film) 4 to be a lower layer of a wiring is formed on a substrate 6 comprising an insulating substrate 6a and a lower layer 6b. The film is formed to have a thickness. In the case of a transmission type liquid crystal display device, the insulating film 4 needs to be a transparent film, and has a refractive index of 1.4 to 1.9.
About 5 insulating films are appropriate. Examples of the material of the insulating film 4 include SiNx and SiOx.
An oxide film (SiO ₂ ) is used.

Subsequently, as shown in FIG. 1B, a concave portion 4a is formed in the insulating film 4 by patterning, and the insulating film pattern 4 is formed.
(For convenience, it is represented by the same reference number as the insulating film at the time of film formation). Here, in the recess 4a, the signal wiring 2 will be described later.
Therefore, the concave portion 4a needs to be formed to have a width slightly larger than the line width of the signal wiring 2. Further, the concave portion 4a must be formed to a depth corresponding to the thickness of the wiring, that is, a depth of about several thousand to 10,000 Å since the step due to the thickness of the wiring must be absorbed.

Next, a metal wiring material, for example, a conductive film made of an Al-based metal material is deposited on the entire surface of the insulating film pattern 4 to a film thickness of, for example, about 7000 °, and then photolithography is performed.
After each step of etching and resist peeling, Fig. 1 (C)
As shown in FIG. 5, the signal wiring 2 is formed in each recess 4a of the insulating film pattern.

Next, as shown in FIG. 1D, the upper insulating film (the second insulating film)
Is formed. The material of the upper insulating film 5 may be the same as or different from the material of the insulating film pattern 4. Here, the same material is used.
In this step, the flatness of the upper surface of the upper insulating film 5 is controlled by controlling the space d between the wall surface of the concave portion 4a (that is, the surface of the insulating film pattern defining the concave portion 4a) and the side surface of the wiring facing the surface. Is controlled. For example, if the space d is too wide, even if the upper insulating film 5 is formed, the scanning wiring 1
The flatness is not improved because a step is generated at the end of. On the other hand, if it is too narrow, the upper insulating film 5 cannot fill the space d, so that a cavity is generated in the space d. For this reason, a space width of, for example, about 1.0 μm is secured as the space d. Since the upper insulating film 5 is intended to planarize the upper layer by filling the space d at the time of film formation, the thickness t of the upper insulating film 5 at the time of film formation is schematically shown in FIG. Must be at least １ ／ times the space d. For example, when the space d is about 1.0 μm, it is necessary to form an oxide film SiO ₂ of about 5000 ° or more. Actually, in order to improve the flatness of the upper surface, the upper insulating film 5 having a thickness of about 15000 °, that is, about 1.5 μm is formed. Thus, the upper insulating film 5 is formed on the wiring 2 and the insulating film pattern 4, and the surface is flattened.

Next, on the upper insulating film 5, in a state where the peripheral portion overlaps with the signal wiring 2 on one side and the scanning wiring 1 on one side (not shown in FIG. 1), ITO (indium tin oxide) is used. ) To form a transparent pixel electrode 3 (see FIG. 3).

Thereafter, application of an alignment film, rubbing treatment, and the like are performed by a known method to complete a drive substrate. Then, after the driving substrate and the counter substrate are bonded together and liquid crystal is injected, an active matrix liquid crystal display device is completed through necessary processes such as sealing and bonding of a polarizing plate.

The "lower layer 6b" included in the substrate 6
1 comprehensively expresses various films and patterns formed between the insulating film 4 and the insulating substrate 6b shown in FIG. 1A. In addition to the TFT, the insulating film pattern 4, the scanning wiring 1 and the upper insulating film 5 thereon.
The insulating film pattern 4, the scanning wiring 1, and the upper insulating film 5 are formed by the same method as the method of forming the insulating film pattern 4, the signal wiring 2, and the upper insulating film 5 described above. In this case, the upper insulating film on the scanning wiring 1 functions as an interlayer insulating film between the scanning wiring 1 and the signal wiring 2.

In the above-described manufacturing method, after the upper insulating film 5 is deposited in the step shown in FIG.
The pixel electrode 3 is formed thereon. After the step shown in FIG. 1D, as shown in FIG. 3
May be formed. For example, when the upper insulating film 5 of 15000 ° is formed, the film thickness of the upper insulating film 5 is reduced to about 7000 ° by etching back at 8000 °.

The reason for reducing the thickness of the upper insulating film 5 is as follows. It can be said that the upper insulating film 5 is preferably thick for filling the space d and improving the flatness. However, the upper insulating film 5 has fine contact holes (FIG. 1 and FIG. 2) for electrically connecting the upper pixel electrode 3 to the lower layer 6b via a conductive film pattern formed simultaneously with the wiring 2. (Not shown), and the upper insulating film 5
As the thickness increases, it becomes more difficult to form and control a fine pattern by etching. The thickness of the pixel electrode 3 is, for example, only about 1000 to 1500 ° when ITO or the like is used. Considering the coverage of the thin-film pixel electrode 3 in the contact hole, the insulating film layer in the portion where the contact hole is formed is thick. Better not. Therefore, by performing etch back on the entire upper insulating film 5 formed to be thicker, the insulating film 5 can be controlled to an arbitrary thickness. Further, by performing the etch back, the insulating film 5 can be formed.
Since the recessed state of the insulating film 5 on the space which is slightly generated at the time of formation can be removed, the flatness is further improved. Therefore,
The flatness of the pixel electrode 3 formed in a state where the peripheral portion overlaps the signal wiring 2 and the scanning wiring 1 on one side is also improved as compared with the case where the upper insulating film 5 is not thinned.

The pixel electrode 3 is electrically connected to the lower layer 6b.
The formation position of the fine contact hole 7 for connection to the substrate can be appropriately selected. FIG. 5 shows an example in which the contact hole 7 is formed below the concave portion 4a.

The contact hole 7 is formed in the insulating film (SiO ₂ film) 4 in the step shown in FIG. 1 (B), after which a concave portion 4a is formed in the thinned portion of the upper insulating film below the concave portion 4a. As a result, a contact hole 7 extending from the bottom of the concave portion 4a to the lower layer is obtained in the insulating film 4. Thereafter, in the same manner as described with reference to FIG. 1C, a conductive film is deposited on the entire surface of the insulating film pattern 4 including the contact hole 7 and the inside of the concave portion 4a. After that, as shown in FIG. 5, the wiring 2 integrated with the conductive film of the contact hole 7 is formed in each recess 4a. Thus, conduction between the wiring 2 and the substrate lower layer 6b can be achieved via the contact hole 7. The thickness of the insulating film at the time of forming the contact hole is controlled by the thickness at the time of forming the insulating film 4 and the amount of digging of the concave step. The smaller the difference, the easier the formation of the contact hole. actually,
After forming a film of about 10,000 ° as the insulating film 4,
Å By forming in a concave shape by patterning,
The thickness of the insulating film 4 at the contact hole forming portion is 3000
Å

Although the present invention has been described with reference to some examples, the present invention is not limited to these, and can be variously modified.

For example, although the active matrix type liquid crystal display device of the above embodiment is of a transmission type, it may be of a reflection type. In the case of the reflection type, the pixel electrode 3 is not transparent and may be formed using aluminum or the like, and the insulating films 4 and 5 do not need to be transparent films. In any case, the present invention relates to enlargement of a pixel electrode formation region by flattening a wiring region and a region between wirings, and it is easily understood that the present invention is applicable to any type of liquid crystal display device. I can do it.

Further, in the above embodiment, the pixel electrode 3 is formed in a substantially rectangular shape, but may be formed in a partially cutout shape if necessary. In addition, each pixel electrode 3 is formed such that the peripheral portion is overlapped with only one of the two adjacent scanning lines 1 or only one of the two adjacent signal lines 2, but is also adjacent to the two adjacent scanning lines 1. The peripheral portions may also be formed on the two signal wirings 2 so as to overlap.

In the above embodiment, the scanning wiring 1 is formed on the lower side, and the signal wiring 2 is formed on the upper side.

In the above embodiment, each step is performed not only on the upper signal wiring 2 but also on the lower scanning wiring 1, but is performed only on the upper signal wiring 2. You may. Further, different flattening processes may be performed on the signal wiring 2 and the scanning wiring 1, respectively.

Further, a switching element other than a TFT can be used.

As described above, an example in which the present invention is applied to a driving substrate of an active matrix type liquid crystal display device, in particular, to each signal wiring region and a region therebetween and each scanning wiring region and a region therebetween, with reference to FIGS. As described above, as will be easily understood by those skilled in the art, the present invention can be similarly applied to regions other than these regions, for example, regions such as a gate electrode and a drain electrode. Further, the application of the present invention is not limited to the liquid crystal display device. In short, as shown in FIG.
The present invention can be applied to any location where the surface is to be flattened by absorbing a step due to the conductive film C constituting the wiring and the electrode. FIG. 6 shows the conductive film C
FIG. 4 is a plan view showing a state in which is stored in a concave portion 4a of an insulating film pattern (first insulating film). Although it is a plan view,
For easy understanding, the conductive film C is hatched.

[0038]

As is clear from the above, according to the present invention, the wirings and all the regions between the wirings have smooth flatness, and the pixel electrodes are formed on the flat regions. Thereby, the obstacle due to the step in the rubbing treatment for performing the liquid crystal alignment treatment is reduced, and the deterioration of display quality such as poor alignment is prevented. In addition, the flatness between and between the wirings is continuous, and the wirings are also covered with the upper insulating film, so that a pixel electrode can be formed in a layer above the wirings, the pixel electrode can be formed in a wide range, and the opening can be formed. The rate can be improved. Further, in the future, with the advance of high definition, it is necessary to reduce the resistance of the wiring, and for example, it is conceivable that the thickness of the wiring will be increased. It is possible to easily cope with various film thicknesses only by controlling the film thickness when forming the insulating film pattern. As described above, according to the present invention, a high-definition active matrix liquid crystal display device having a high aperture ratio with good display quality can be provided.

[Brief description of the drawings]

FIG. 1 is a simplified process diagram showing a method for manufacturing a liquid crystal display device according to an embodiment of the present invention, and FIG. 1 (D) is 1E-1 in FIG.
It represents a section taken along the line E.

FIG. 2 is a simplified process chart showing a modification of the manufacturing method shown in FIG.

FIG. 3 is a simplified plan view of a main part of the liquid crystal display device manufactured in the process shown in FIG. 1 or FIG.

FIG. 4 is a diagram illustrating a relationship between a space between a concave wall surface of an insulating film pattern and a wiring side surface and a film thickness of an upper insulating film according to the present invention.

FIG. 5 is a simplified cross-sectional view of a modification of the liquid crystal display device of FIG.

FIG. 6 is a simplified plan view showing a state where a conductive film is formed in a concave portion of an insulating film pattern by applying the present invention.

7A is a simplified plan view of a main part of a conventional liquid crystal display device, and FIG. 7B is a sectional view taken along line 7B-7B of FIG.

8A is a simplified plan view of a main part of a conventional liquid crystal display device, and FIG. 8B is a sectional view taken along line 8B-8B of FIG. 8A.

FIG. 9 is a schematic sectional view when a pixel electrode is formed on a wiring in the conventional structure shown in FIG. 7;

FIG. 10 is a schematic sectional view when a pixel electrode is formed on a wiring in the conventional structure shown in FIG. 8;

[Explanation of symbols]

 1: scanning wiring, 2: signal wiring, 3: pixel electrode, 4: insulating film pattern, 4a: concave portion of insulating film pattern 5: upper insulating film, 6: substrate composed of insulating substrate 6a and lower layer 6b, 7: contact Hole C: conductive film.

Continued on the front page F-term (reference) 2H090 HA03 HB03X HC01 HC11 HC12 HC16 HC18 HD03 JA05 JB02 JD14 LA04 2H092 JA46 KA16 KA18 KB14 KB25 MA13 MA17 NA07 NA19 NA25 PA02 5C094 AA02 AA12 BA03 BA43 CA19 CA24 DA14 DA15 FB04 A15 EB04 DD21 QQ19

Claims (12)

[Claims] In an active matrix type liquid crystal display device in which a plurality of scanning wirings and signal wirings intersect on an insulating substrate, at least one of the scanning wirings and the signal wirings is formed in a recess provided in an insulating film pattern. And an upper insulating film having a continuous surface is formed on the insulating film pattern and the wiring in the concave portion. 2. The liquid crystal display device according to claim 1, wherein the one wiring is a wiring disposed above the other wiring, and the pixel electrode and the wiring are disposed on an upper insulating layer on an insulating film pattern. A liquid crystal display device formed on a film. 3. The liquid crystal display device according to claim 1, wherein the thickness of the wiring in the recess is substantially equal to the depth of the recess in the insulating film pattern. 4. The liquid crystal display device according to claim 1, wherein a thickness of the upper insulating film is determined by a thickness of a surface of an insulating film pattern defining the concave portion and a thickness of a wiring facing the surface. A liquid crystal display device characterized by being at least half the space between the side and the side. 5. The liquid crystal display device according to claim 1, wherein the insulating film pattern is formed of a transparent film having a refractive index of 1.4 to 1.95. Characteristic liquid crystal display device. 6. The liquid crystal display device according to claim 1, wherein the insulating film pattern has a contact hole extending from a bottom of the concave portion to a lower layer. Characteristic liquid crystal display device. 7. A method of manufacturing an active matrix liquid crystal display device in which a plurality of scanning wirings and signal wirings intersect on an insulating substrate, wherein: a step of forming an insulating film pattern; and a step of forming a recess in the insulating film pattern. Forming a wiring of one of a scanning wiring and a signal wiring in the concave portion; and forming an upper insulating film having a continuous surface on the insulating film pattern and the wiring. how to. 8. The method according to claim 7, wherein the one wiring is a wiring arranged above the other wiring, and further comprising a step of forming a pixel electrode on the upper insulating film. A method comprising: 9. The method according to claim 7, further comprising, after forming the upper insulating film, thinning the upper insulating film by an etch-back method. 10. The method according to claim 7, further comprising, after forming a recess in the insulating film pattern, forming a contact hole extending from a bottom of the recess to a lower layer. The method according to claim 1, further comprising, in the step of forming the wiring, burying the same conductive material as the wiring in the contact hole at the same time as forming the wiring. 11. The method according to claim 7, wherein the upper insulating film is formed immediately after the surface of the insulating film pattern defining the recess and the side surface of the wiring facing the surface. A thickness of at least half the space between the two. 12. A first insulating film having a concave portion, a conductive film provided in the concave portion and having a thickness substantially equal to a depth of the concave portion, and a conductive film provided on the first insulating film and the conductive film. And a second insulating film provided continuously.