JP3583120B2 - Reflection type liquid crystal display device and manufacturing method thereof - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reflection type liquid crystal display device and a method of manufacturing the same, and more particularly, to a reflection type liquid crystal display device that reflects externally incident light to be a display light source and a method of manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a reflection type liquid crystal display device (liquid crystal display) which does not need to include a backlight as a light source is provided by providing a reflection plate inside a device and reflecting a light incident from the outside by the reflection plate to form a display light source. display (LCD) is known.
[0003]
FIG. 9 is a partial sectional view of a conventional reflection type liquid crystal display device. As shown in FIG. 9, the reflective LCD 1 includes a lower substrate 2 and an opposing substrate 4 that faces the lower substrate 2 with a liquid crystal layer 3 interposed therebetween.
[0004]
The lower substrate 2 has a semiconductor element 5, a drain wiring 6, and a convex pattern 7 formed on an insulating substrate 2a. An insulating layer 8 is formed so as to cover the semiconductor element 5, the drain wiring 6 and the convex pattern 7, and a reflective electrode (reflective plate) 9 is formed on the insulating layer 8. The opposing substrate 4 has an insulating substrate 4a and a transparent electrode 4b formed on the liquid crystal layer 3 side.
[0005]
The insulating layer 8 made of an organic material, an inorganic material, or an organic material and an inorganic material, which is stacked on the drain wiring 6, is used to passivate the insulating film or the semiconductor element 5 when forming irregularities on the insulating substrate 2a. Also serves as a membrane.
[0006]
[Problems to be solved by the invention]
However, if the continuous convex pattern 7 is not formed on the drain wiring 6, only the thin insulating layer 8 covers the drain wiring 6 (see FIG. 9), and thus the color of light reflected by the drain wiring 6 Is yellowish, and affects the display characteristics of the reflective LCD 1.
[0007]
FIG. 10 is an explanatory diagram showing a light reflection state by the reflection type LCD of FIG. As shown in FIG. 10, the incident light Li reaches the lower substrate 2 from the opposing substrate 4 through the liquid crystal layer 3, is reflected there, becomes reflected light Lr, passes through the liquid crystal layer 3 again, and returns to the opposing substrate 4. Is emitted outside.
[0008]
That is, when only the thin insulating layer 8 covers the drain wiring 6 made of a metal material, the distance between the drain wiring 6 sandwiching the liquid crystal layer 3 and the opposing substrate 4 is wider than that of the reflective electrode 9 sandwiching the liquid crystal layer 3. Thus, the reflected light Lr reflected by the drain wiring 6 has a larger birefringence (Δn · d) than the reflected light Lr reflected by the reflective electrode 9 and becomes yellowish. For this reason, at the time of white display, yellowish white is displayed.
[0009]
An object of the present invention is to provide a reflective liquid crystal display device that prevents reflected light from taking on a yellow tint and does not display yellowish white during white display, and a method of manufacturing the same.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a reflection type liquid crystal display device according to the present invention has a liquid crystal layer sandwiched between a lower substrate and a lower substrate disposed opposite to each other, and a reflection electrode provided on the lower substrate. In a reflective liquid crystal display device that reflects external incident light and serves as a display light source, the reflective electrode has a shape reflecting the uneven pattern on an insulating film having an uneven pattern formed on the surface. In the gap formed by the adjacent reflective electrodes, on the wiring formed on the lower substrate, only the convex portion not including the concave portion of the insulating film is located. It is characterized in that the part is surrounded.
[0011]
By having the above configuration, the reflective electrode is laminated on the insulating film having the uneven pattern formed on the surface thereof with the shape reflecting the uneven pattern, and the wiring formed on the lower substrate is formed. In the gap formed by the adjacent reflective electrodes above, only the convex portion not including the concave portion of the insulating film is located, and the convex portion surrounds the periphery of the pixel portion. Thus, the reflection electrode provided on the lower substrate prevents the reflected light, which reflects the incident light from the outside, from becoming yellowish, and does not display yellowish white when displaying white.
[0012]
Further, the reflective liquid crystal display device can be realized by the method of manufacturing a reflective liquid crystal display device according to the present invention.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a partial sectional view of a reflection type liquid crystal display device according to one embodiment of the present invention. As shown in FIG. 1, a reflective liquid crystal display (LCD) 10 includes a lower substrate 11, a liquid crystal layer 12, and an opposing side disposed to face the lower substrate 11 via the liquid crystal layer 12 inside the device. It has a substrate 13.
[0015]
The reflective LCD 10 employs, for example, an active matrix system in which a thin film transistor (TFT) is provided as a switching element for each pixel.
[0016]
The lower substrate 11 includes an insulating substrate 14, a TFT 15, a drain wiring 16, a convex pattern 17, an insulating layer 18, and a reflective electrode 19. The TFT 15, the drain wiring 16, and the convex pattern 17 formed on the insulating substrate 14 are covered with an insulating layer 18, and a contact hole reaching the source electrode of the TFT 15 is formed in the insulating layer 18. .
[0017]
A reflection electrode 19 is formed on the insulating layer 18 except for a portion covering the convex pattern 17 formed on the drain wiring 16. That is, the drain wiring 16 is covered with the convex pattern 17 and the insulating layer 18, and the reflective electrode 19 is laminated on the insulating layer 18.
[0018]
The reflection electrode 19 is connected to a source electrode or a drain electrode of the TFT 15 and has a function as a reflection plate and a pixel electrode. The reflection electrode 19 reflects external incident light to serve as a display light source. .
[0019]
The opposing substrate 13 has an insulating substrate 20 and a transparent electrode 21 positioned on the liquid crystal layer 12 side thereof. Light incident on the opposing substrate 13 passes through the liquid crystal layer 12 to the lower substrate 11. Then, the light is reflected there and exits from the opposite substrate 13 through the liquid crystal layer 12 again.
[0020]
FIG. 2 is a plan view showing an example of forming one pixel of the convex pattern in FIG. As shown in FIG. 2, the convex pattern 17 is formed by a plurality of linear convex portions 17a which are randomly arranged in a plane formed by a rectangular frame and are connected to each other at an arbitrary bending angle. I have.
[0021]
That is, the reflective electrode 19 is laminated on the insulating layer having the convex and concave pattern 17 formed on the surface thereof, and the surface of the reflective electrode 19 has a shape reflecting the concave and convex pattern.
[0022]
The frame portion of the projecting pattern 17 is formed by a frame projecting portion 17b whose width is wider than the width of the linear projecting portion 17a formed in another region so that the drain wiring 16 can be covered. , On the drain wiring 16. An insulating layer 18 is formed to cover the convex pattern 17.
[0023]
As described above, the insulating layer 18 of the reflective LCD 10 is made of any of an organic material, an inorganic material, or an organic material and an inorganic material, and the film thickness of the upper part of the drain wiring 16 is a reflection in the liquid crystal display region. It is formed so as to be equal to or thicker than the convex portion of the concave / convex pattern of the electrode 19 (convex height on the drain wiring 16 ≧ convex convex portion of the reflective electrode 19).
[0024]
Therefore, by laminating the film forming the convex pattern 17 and the film forming the insulating layer 18 on the drain wiring 16, the insulating layer of the concave / convex pattern having a rounded convex shape at the tip is formed on the upper layer of the drain wiring 16. Since the layer is formed, the upper layer of the drain wiring 16 can be made to have the same thickness as the convex portion of the concave / convex pattern in the liquid crystal display region so as not to be lower than at least the concave portion of the concave / convex pattern.
[0025]
FIG. 3 is an explanatory diagram showing a light reflection state of the reflective LCD of FIG. As shown in FIG. 3, the incident light Li that has entered the opposing substrate 13 and has reached the lower substrate 11 through the liquid crystal layer 12 is reflected by the drain wiring 16 to become reflected light Lr. The light is emitted to the outside of the opposing substrate 13.
[0026]
At this time, in the reflective LCD 10, the upper layer of the drain wiring 16 also has the same film thickness as the convex portions of the concave and convex pattern of the reflective electrode 19, which is a liquid crystal display area. The space between the opposing substrates 13 does not become wider than other portions.
[0027]
That is, the contact surface of the lower substrate 11 with the liquid crystal layer 12 is so set that the distance between the opposing substrate 13 and the reflective electrode 19 or the lower substrate 11 on which the reflective electrode 19 is formed is equal. It is formed in one state.
[0028]
Therefore, the reflected light Lr reflected by the drain wiring 16 and the reflected light Lr reflected by the reflective electrode 19 do not have different birefringences (Δn · d) (see FIG. 9). For this reason, it is possible to prevent the color of the reflected light Lr from the drain wiring 16 from shifting from yellow to blue and becoming yellowish.
[0029]
FIG. 4 is a sectional view showing a positional relationship between a drain wiring and a pixel electrode in the reflective LCD of FIG. As shown in FIG. 4, in the case of the reflective LCD 10, the surface of the insulating layer 18 covering the convex pattern 17 on the drain wiring 16, that is, adjacent to the surface of the drain wiring 16 formed on the lower substrate 11. The convex pattern 17 and the insulating layer 18 are located in the gap formed by the reflective electrode 19, and the drain wiring 16 and the reflective electrode (pixel electrode) 19 are formed without overlapping (see (a)).
[0030]
In other words, the positional relationship between the drain wiring 16 and the reflective electrode 19 of the reflective LCD 10 is not a state where the end of the drain wiring 16 and the end of the reflective electrode 19 are on the same line and overlapped (see the dotted line (b)). The end of the wiring 16 and the end of the reflective electrode 19 are not on the same line, and they are separated from each other (see the dotted line (a)).
[0031]
For this reason, when the drain wiring 16 and the reflective electrode 19 overlap (see (b)), it is inevitable that the parasitic capacitance becomes large and the pixel voltage fluctuates. Since the pixel voltage does not fluctuate, the display characteristics are not adversely affected when the voltage polarities of the two drain lines are the same as in the case of the gate line inversion drive.
[0032]
FIG. 5 is an explanatory view showing a reflective electrode manufacturing process in the manufacturing process of the reflective LCD shown in FIG. As shown in FIG. 5, first, a TFT 15 and a drain wiring 16 are formed on an insulating substrate 14 (see (a)).
[0033]
Next, after applying an organic resin, for example, on the insulating substrate 14 on which the drain wiring 16 is formed, an exposure and development process is performed, and an uneven pattern is formed on the surface of the reflective electrode 19 with a convex pattern forming mask. A plurality of convex patterns 17 to be formed are formed (see (b)). At this time, the frame portion of the convex pattern 17 is positioned on the drain wiring 16.
[0034]
Next, an insulating layer 18 made of an organic resin is formed so as to cover the convex pattern 17 to form a smooth uneven shape, and then exposure and development are performed to open a contact hole (see (c)). When the insulating layer 18 is formed, the thickness of the upper part of the drain wiring 16 is made equal to or larger than that of the concave and convex pattern of the reflective electrode 19 which is a liquid crystal display region by the convex pattern 17.
[0035]
Next, after forming an aluminum (Al) thin film covering the insulating layer 18 together with the contact hole in accordance with the formation position of the reflective electrode 19, exposure and development are performed to form the reflective electrode 19 as a reflective pixel electrode. (See (d)).
[0036]
In forming the reflection electrode 19, the drain wiring 16 and the reflection electrode 19 are prevented from overlapping each other. The material of the reflective electrode 19 is not limited to Al, and may be formed of another conductive material.
[0037]
FIG. 6 is an explanatory diagram of a manufacturing method (part 1) in the reflective electrode manufacturing process of FIG. As shown in FIG. 6, when the reflective electrode 19 is formed, after forming the resist pattern 22 of the reflective electrode 19 (see FIG. 6A), the etching process of the reflective electrode 19 is performed for a long time, so that the processing amount for the Al thin film is increased. And the width of the completed pattern is made narrower than the resist pattern 22 (see (b)). Thereby, it is possible to prevent the reflection electrode 19 from overlapping the drain wiring 16.
[0038]
FIG. 7 is an explanatory diagram of a manufacturing method (No. 2) in the reflective electrode manufacturing process of FIG. As shown in FIG. 7, in the case of this manufacturing method, the resist pattern 22 of the reflective electrode 19 is formed in a pattern that does not overlap with the drain wiring 16, but this is done so that it does not overlap in the mask design stage (( a)), or by extending the development time at the stage of resist development so as not to overlap (see (b)). This prevents the reflection electrode 19 from overlapping the drain wiring 16.
[0039]
A method of forming the upper portion of the drain wiring 16 so as to have a thickness equal to or larger than the convex portion of the concave / convex pattern of the reflective electrode 19 will be described below.
[0040]
FIG. 8 is an explanatory diagram showing the relationship between the mask pattern width and the cross-sectional shape of the convex pattern. As shown in FIG. 8, when the width of the mask pattern is 4 μm, the width is about 7 μm and the step is about 2.2 μm. When the width of the mask pattern is 10 μm, the width is about 10 μm and the step is about 2. 8 μm.
[0041]
That is, as the width of the mask pattern increases, the film thickness of the convex pattern 17 increases, so that the mask pattern width of the convex pattern 17 formed on the drain wiring 16 is changed to the convex portion formed in the region of the reflective electrode 19. By making the width larger than the width, an insulating film having a large thickness can be formed.
[0042]
Similarly, even when an acrylic resin is used for the convex pattern forming film, the film thickness above the drain wiring 16 can be formed to be equal to or greater than the convex portion of the concave / convex pattern of the reflective electrode 19.
[0043]
When an acrylic resin is used, as the line width formed by the photoresist becomes wider, the step after firing becomes higher. Therefore, by utilizing this phenomenon, the convex pattern 17 formed on the drain wiring 19 is formed. Can be formed into a pattern wider than that of the liquid crystal display area, and a layer having a larger thickness than the convex portions of the concave / convex pattern can be formed.
[0044]
As described above, in the reflective LCD 10, first, a convex-shaped insulating layer having a rounded tip is formed on the drain wiring 16, and second, the reflective electrode 19 and the drain wiring 16 overlap. Thirdly, the convex pattern 17 formed on the drain wiring 16 is formed in a pattern having a wider width than that formed in a region overlapping with the reflective electrode 19, so that the reflective electrode It has a configuration in which the convex portion is formed higher than a certain region of 19.
[0045]
That is, a convex pattern 17 and an insulating layer 18 covering the convex pattern 17 are formed on the drain wiring 16 to make the thickness of the liquid crystal layer 12 uniform, and at the same time, the drain wiring 16 is formed to reduce the parasitic capacitance. The insulating layer 18 is arranged between the adjacent reflective electrodes 19 so that the reflective electrode 19 located above the reflective electrode 19 does not overlap.
[0046]
As a result, the insulating layer 18 formed on the drain wiring 16 so as to cover the convex pattern 17 is formed at a position where each end face of the reflection electrode 19 on both sides does not overlap with the extension of both sides of the drain wiring 16 and on both sides. It is formed and arranged at the same height as the reflective electrode 19.
[0047]
The configuration in which the distance between the pixel electrodes (reflection electrodes 19) is wider than the width of the drain wiring 16 is an ideal state, but the state in which each end face of the reflection electrode 19 coincides with both side surfaces of the drain wiring 16 may be used. It is sufficient that at least each end face of the reflection electrode 19 on both sides does not overlap each other so as to enter the extension of both side faces of the drain wiring 16. For example, even if only one of them overlaps due to misalignment or the like, it is in a flush state. If so, the necessary effects can be obtained.
[0048]
As described above, according to the present invention, the convex pattern 17 and the insulating layer 18 on the upper part of the drain wiring 16 are used as a part of the pattern for forming the concave and convex shape of the reflective electrode 19, and the reflective electrode 19 is connected to the drain wiring 16. It is formed higher than the convex portion of the liquid crystal display portion so that it does not overlap and the insulating layer 18 and the reflective electrode 19 are flush with each other.
[0049]
As a result, it is possible to suppress the coloring of the reflected light Lr reflected by the drain wiring 16 from becoming yellowish, and to improve the display of yellowish white during white display.
[0050]
That is, when the voltage polarities of the two drain lines are the same as in the case of the gate line inversion drive, not only the parasitic capacitance that adversely affects the display characteristics can be reduced, but also the color of the light reflected by the drain lines 16 can be reduced. The taste can be improved and the display characteristics can be improved.
[0051]
In the above-described embodiment, the switching element is not limited to the TFT 15, and another switching element such as a diode may be used. Further, the film thickness may be adjusted by laminating a film for forming the convex pattern 17 and a film for forming the insulating layer 18 on another wiring made of a metal material, not limited to the drain wiring 16.
[0052]
【The invention's effect】
As described above, according to the present invention, the reflective electrode is laminated on the insulating film having the concave / convex pattern formed on the surface, with the shape reflecting the concave / convex pattern, and the lower substrate In the gap formed by the adjacent reflective electrodes on the wiring formed in the above, only the convex portion not including the concave portion of the insulating film is located, and the convex portion surrounds the periphery of the pixel portion. Therefore, the reflective electrode provided on the lower substrate prevents the reflected light, which reflects the incident light from the outside, from taking on a yellow tint, and does not display yellowish white when displaying white.
[0053]
Further, the reflective liquid crystal display device can be realized by the method of manufacturing a reflective liquid crystal display device according to the present invention.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of a reflection type liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a plan view showing an example of forming one pixel of a convex pattern in FIG. 1;
FIG. 3 is an explanatory diagram showing a light reflection state of the reflection type LCD of FIG. 1;
FIG. 4 is a sectional view showing a positional relationship between a drain wiring and a pixel electrode in the reflective LCD of FIG. 1;
FIG. 5 is an explanatory view showing a reflective electrode manufacturing process in the manufacturing process of the reflective liquid crystal display device shown in FIG.
6 is an explanatory view of a manufacturing method (part 1) in the reflective electrode manufacturing process of FIG.
FIG. 7 is an explanatory diagram of a manufacturing method (part 2) in the reflective electrode manufacturing process of FIG.
FIG. 8 is an explanatory diagram showing a relationship between a mask pattern width and a cross-sectional shape of a convex pattern.
FIG. 9 is a partial sectional view of a conventional reflection type liquid crystal display device.
FIG. 10 is an explanatory diagram showing a light reflection state of the reflection type LCD of FIG. 9;
[Explanation of symbols]
10. Reflective LCD
11 Lower substrate 12 Liquid crystal layer 13 Opposite substrate 14 Insulating substrate 15 TFT
Reference Signs List 16 drain wiring 17 convex pattern 17a linear convex part 17b convex part for frame 18 insulating layer 19 reflective electrode 20 insulating substrate 21 transparent electrode 22 resist pattern Li incident light Lr reflected light

Claims (10)

A reflection type liquid crystal display device having a lower substrate disposed opposite to the substrate and a liquid crystal layer sandwiched between the opposite substrate, and a reflection electrode provided on the lower substrate, which reflects an incident light from the outside and serves as a display light source. At
The reflective electrode is stacked on an insulating film having a concave-convex pattern formed on a surface thereof, in a shape reflecting the concave-convex pattern,
In the gap formed by the adjacent reflective electrode on the wiring formed on the lower substrate, only the convex portion not including the concave portion of the insulating film is located, and the peripheral portion of the pixel portion is formed by the convex portion. A reflective liquid crystal display device, which is enclosed. 2. The reflective liquid crystal display device according to claim 1, wherein the insulating film includes a convex pattern formed on the lower substrate and an insulating layer covering the convex pattern. 3. The convex pattern of the insulating film located in the gap above the wiring, wherein the convex pattern is formed higher than the reflective electrode formed in the pixel electrode section. Reflective liquid crystal display. The width of the convex pattern of the insulating film formed on the wiring is wider than the width of the convex pattern formed in another region, and is not narrower than the width of the wiring. The reflective liquid crystal display device according to claim 1. The reflective wiring according to any one of claims 1 to 4, wherein the wiring and the reflective electrode are formed at positions where an end of the wiring and an end of the reflective electrode do not overlap. Liquid crystal display. 5. The reflection type liquid crystal display device according to claim 1, wherein the wiring and the reflection electrode are formed at a position where a side surface of the wiring and an end face of the reflection electrode coincide with each other. . 7. The reflection type liquid crystal display device according to claim 1, wherein the liquid crystal is driven by an active matrix method in which a thin film transistor as a switching element is provided for each pixel. A reflection type liquid crystal display device having a lower substrate disposed opposite to the substrate and a liquid crystal layer sandwiched between the opposite substrate, and a reflection electrode provided on the lower substrate, which reflects an incident light from the outside and serves as a display light source. In the manufacturing method of
Forming a switching element and a wiring on the insulating substrate of the lower substrate;
On the wiring and the insulating substrate, a plurality of convex patterns for forming a concavo-convex pattern on the surface of the reflective electrode, and a line width on an upper part of the wiring is convex of the convex pattern in the concavo-convex pattern of the reflective electrode. In comparison with the portion, the width is not narrower than the width of the wiring, only the convex portion not including the concave portion of the insulating film is located on the wiring, the periphery of the pixel portion by the convex portion. Forming a frame so as to be enclosed;
The insulating film is formed on the insulating substrate so as to cover the convex pattern, so that a film thickness of the upper part of the wiring is equal to or larger than a convex part of the reflective electrode in a liquid crystal display area. Forming a smooth uneven shape;
A step of laminating a conductive thin film covering the insulating layer corresponding to the position where the reflective electrode is formed, and forming the reflective electrode so as not to overlap the wiring. Manufacturing method. When forming the reflective electrode, after forming a resist pattern of the reflective electrode, by performing a long etching process of the reflective electrode, to increase the processing amount for the conductive thin film, a pattern completed than the resist pattern 9. The method for manufacturing a reflective liquid crystal display device according to claim 8, wherein the width of the liquid crystal display device is reduced. By making the mask pattern width of the convex pattern formed on the wiring larger than the width of the convex part formed in the region of the reflective electrode, the thickness of the upper part of the wiring is reduced by the irregular pattern of the reflective electrode. 9. The method of manufacturing a reflective liquid crystal display device according to claim 8, wherein the reflective liquid crystal display device is formed so as to be equal to or thicker than the convex portion.

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