JP2002229014A - Liquid crystal cell, method of manufacturing liquid crystal cell, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost semitransmissive liquid crystal display device with high luminance. SOLUTION: The array substrate has switching elements and a reflection layer, a coloring layer formed so as to cover the switching elements and the reflection layer and provided with contact holes and translucent pixel electrodes formed on the coloring layer, connected to the switching elements via the contact holes, and provided with a reflection mode display region superimposed on the reflection layer and a transmission mode display region which is not superimposed on the reflection layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transflective liquid crystal cell for performing color display, a method for manufacturing a liquid crystal cell, and a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a reflection type liquid crystal display device has been widely used as a display of a portable telephone or a portable computer. This is because the reflective liquid crystal display device can perform display using external light, so that there is no need for a backlight or the like, and power consumption can be significantly reduced. However, the reflection type liquid crystal display device naturally has a problem that the display itself becomes dark in a dark place, and the surrounding environment to be used is limited. Recently, in order to solve the above problems, a so-called transflective liquid crystal display device having both a reflection type and a transmission type function has been developed. For example, JP-A-2000-19
563 discloses a liquid crystal display device having a reflective layer and a transmissive layer in a pixel, and also discloses a technique of disposing a colored layer in front of the liquid crystal layer for performing color display.

[0003]

However, when the colored layer is disposed in front of the liquid crystal layer, that is, on the side of the counter substrate, a high precision alignment accuracy is required when bonding the counter substrate and the array substrate. Is required, which causes an increase in manufacturing cost. Further, in order to cope with a slight misalignment, it is necessary to arrange a thick light-shielding film or the like between the pixels, which causes a problem that the luminance of the display is reduced. The present invention has been made in view of the above problems, and has as its object to provide a liquid crystal cell which performs high-luminance display and is inexpensive to manufacture, a method of manufacturing the same, and a liquid crystal display device.

[0004]

According to the present invention, there is provided a light-transmitting array substrate, a light-transmitting opposing substrate disposed opposite to the array substrate, and a light-transmitting opposing substrate disposed between the array and the opposing substrate. In a liquid crystal cell having a liquid crystal composition, the array substrate is formed over the switching element and the reflective layer, the switching element and the reflective layer, and a colored layer having a contact hole; And a light-transmitting pixel electrode that is connected to the switching element via the pixel electrode and has a region for displaying a reflective mode that is superimposed on the reflective layer and a region for displaying a transmissive mode that is not superimposed on the reflective layer. Is a liquid crystal cell. Also,
The present invention provides a liquid crystal cell having a light-transmitting array substrate, a light-transmitting counter substrate disposed to face the array substrate, and a liquid crystal composition disposed between the array substrate and the counter substrate. And a lighting device that illuminates the liquid crystal cell from the array substrate side, wherein the array substrate is formed so as to cover the switching element and the reflective layer, and the switching element and the reflective layer. A colored layer having a region formed on the colored layer, connected to the switching element through a contact hole, and displaying a reflective mode that is superimposed on the reflective layer and a region that is displayed in a transmissive mode that is not superimposed on the reflective layer. And a light-transmitting pixel electrode.

Further, according to the present invention, there is provided a method for manufacturing a liquid crystal cell in which one substrate and another substrate are bonded to each other and a liquid crystal is sealed in a gap between the two substrates. Forming a colored layer material over the switching element and the reflective layer, patterning the colored layer material to form a colored layer having a contact hole, and connecting to the switching element via the contact hole on the colored layer Forming a pixel electrode having a light-transmitting property to overlap with the reflective layer.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing a liquid crystal cell and a liquid crystal display device according to the present embodiment, and FIG. 2 is a partial plan view of an array substrate 1. In addition,
FIG. 1 is a sectional view taken along the line AA ′ in FIG. First, the structure of the array substrate 1 is such that a thin film transistor 1
10 are formed. This thin film transistor 110
Is a semiconductor layer 111 made of polycrystalline silicon, and a gate insulating film 11 made of a silicon oxide film formed thereon.
2, a gate electrode 113 made of a molybdenum-tungsten alloy formed on the gate insulating film, an interlayer insulating film 114 formed of a silicon oxide film formed over the gate electrode 113, an interlayer insulating film 114 and a gate insulating film 1
12 through the contact holes formed in the semiconductor layer 1
Source electrode 11 made of aluminum connected to 11
It is a so-called coplanar type composed of 5S and the drain electrode 115D. The reflection layer 102 made of aluminum is formed on the interlayer insulating film 114. Further, the thin film transistor 110 and the reflective layer 102
, A colored layer 103 made of resin is formed.
The coloring layer 103 has a contact hole reaching the source electrode 115S, and a light-transmitting ITO (Indium Tin Oxide) formed on the coloring layer 103.
Is connected to the source electrode 115S via this contact hole.

[0007] An alignment film 105 made of polyimide is formed on the entire surface so as to cover the pixel electrode 104. A λ / 4 plate 107 and a polarizing plate 106 are attached to the back surface of the glass substrate 101. The array substrate 1
The gate electrode 113 is formed integrally with the scanning line 113L, and the drain electrode 115D is formed integrally with the signal line 115L. Then, the scanning line 113L and the signal line 11
A region defined by 5L is defined as a pixel region, and a pixel electrode 104 is formed in the pixel region. An end of the pixel electrode 104 overlaps with the scanning line 113L and the signal line 115L. Further, the reflection layer 102 is formed by being divided into two in the pixel region. The area of the reflective layer 102 with respect to the area of the pixel region was set to be approximately 50%. The region where the reflective layer 102 is present in the pixel region is a region where the reflective mode is displayed, and the region where the reflective layer 102 is not present is a region where the display in the transmissive mode is performed. Returning to FIG. 1, the opposing substrate 2 has an opposing electrode 202 made of ITO and an alignment film 203 made of polyimide over one main surface of a glass substrate 201 having a light-transmitting property. Configuration. Then, on the back surface side of the counter substrate 2, λ / 4
A plate 205 and a polarizing plate 204 are attached. The polarizing plate 204 is disposed so that the transmission axis is orthogonal to the polarizing plate 106, and the λ / 4 plate 205 has an optical axis
The optical axis of the λ / 4 plate 107 is arranged to be orthogonal to the optical axis of the λ / 4 plate 205 at an angle of 45 ° with respect to the transmission axis.

Then, the array substrate 1 and the counter substrate 2 are bonded to each other on one principal surface side, that is, the alignment film 105 and the alignment film 203 by a sealing material (not shown) with a gap therebetween. Liquid crystal 3 is sealed in the gap. This liquid crystal 3 uses a twisted nematic liquid crystal,
It has a retardation of λ / 4. A liquid crystal cell is constituted by the above-described array substrate 1, counter substrate 2, and liquid crystal 3. Further, a backlight 4 as an illumination device for illuminating the liquid crystal cell from the array substrate 1 side.
Are arranged on the back side of the array substrate 1 outside the liquid crystal cell to constitute a liquid crystal display device. Next, an operation of each pixel region of the liquid crystal display device will be described. In each pixel region, the liquid crystal 3 operates due to a potential difference between the pixel electrode 104 and the counter electrode 203, and the light is transmitted / blocked by the polarizing plates 204 and 104. Explaining the display in the transmission mode, first, the light from the backlight 4 is applied to the polarizing plate 10.
6 is linearly polarized. Then, the linearly polarized light is changed to circularly polarized light by the λ / 4 plate 107. Here, the pixel electrode 104 is O
At the FF potential, the circularly polarized light is changed to linearly polarized light by the liquid crystal 3, becomes circularly polarized light again by the λ / 4 plate 205, and a part of the circularly polarized light is transmitted through the polarizing plate 204 to perform bright display. When the pixel electrode is at the ON potential, it passes through the liquid crystal 3 as circularly polarized light, becomes linearly polarized light orthogonal to the transmission axis of the polarizing plate 204 by the λ / 4 plate 205, and does not pass through the polarizing plate 204, thereby providing a dark display.

On the other hand, in the display in the reflection mode, first, the external light is linearly polarized by the polarizing plate 204 and the λ / 4 plate 205
As a result, the light is changed to circularly polarized light and is incident on the liquid crystal 3. Here, when the pixel electrode 104 is at the OFF potential, the liquid crystal 3 changes the light into linearly polarized light, reaches the reflective layer 102 and is reflected. The liquid crystal 3 again changes the light into circularly polarized light, and the λ / 4 plate 205 changes the light into linearly polarized light parallel to the transmission axis of the polarizing plate 204 to perform bright display. When the pixel electrode 104 is at the ON potential, the pixel electrode 104 reaches the reflective layer 102 in the state of circularly polarized light and is reflected therefrom, and further enters the λ / 4 plate 205 in the state of circularly polarized light.
, And becomes a dark display. In either mode of display, light passing through the coloring layer 103 is observed during bright display, so that color display can be performed. Next, a method for manufacturing the liquid crystal cell will be described in detail. First, a method for manufacturing the array substrate 1 will be described. Plasma CV on a 0.7 mm thick glass substrate 101
D (Chemical Vapor Depositi
On) method, an amorphous silicon film is formed to a thickness of 50 nm. Then, the amorphous silicon is annealed in a nitrogen atmosphere at a temperature of 400 ° C. to 600 ° C. for about 1 hour to reduce hydrogen in the amorphous silicon. A so-called dehydrogenation step is performed.

Subsequently, the amorphous silicon is irradiated with a XeCl excimer laser to form a polycrystalline silicon film. Then, this polycrystalline silicon film is formed by CDE (Chemical Dr).
The semiconductor layer 111 is formed by patterning into an island shape by the y etching method. Next, the semiconductor layer 111
And a silicon oxide film having a thickness of 150 nm is formed by plasma CVD using tetraethoxysilane as a source gas to form a gate insulating film 112. Further, a molybdenum-tungsten alloy is further deposited on the
A gate electrode 1 is formed to a thickness of 0 nm and patterned.
13 and the scanning line 113L integral with the gate electrode 113 are formed simultaneously. In this state, the semiconductor layer 111 is doped with phosphorus ions using the gate electrode 113 as a mask.
This doping is performed by ionizing phosphine gas with plasma at a dose of 3 × 10 ¹⁵ / cm ² and an acceleration voltage of 80 keV. By this doping, a low-resistance region is formed in the semiconductor layer 111, and the source electrode 115S and the drain electrode 115D are connected to this region later. After the ion doping, annealing is performed at a temperature of about 400 ° C. to 600 ° C. to activate the doped ions. Further, the semiconductor layer 111 is exposed to hydrogen plasma while being heated to 350 ° C. in order to fill dangling bonds in the semiconductor layer 111.

Next, over the entire surface covering the gate electrode 113,
A silicon oxide film is formed by a plasma CVD method using silane as a source gas, and a contact hole is formed by patterning to form an interlayer insulating film 114. Subsequently, an aluminum film is formed to a thickness of 400 nm by a sputtering method, patterning is performed, and the source electrode 115 is formed.
S, the drain electrode 115D and the signal line 115L integral with the drain electrode 115D are formed simultaneously. Here, the source electrode 115S and the drain electrode 115D are connected to low-resistance regions formed in the semiconductor layer through contact holes formed in the interlayer insulating film 114, respectively. Further, at this time, the reflection layer 102 is simultaneously formed in the pixel region (FIG. 3A). Next, a coloring layer 103 is formed to cover the thin film transistor 110 and the reflective layer 102. First,
20% by weight of red pigment with a particle size of 0.05 to 0.2 μm
3μ of dispersed photo-curable acrylic resin with spinner
m. Then, pre-baking is performed at 90 ° C. for 5 minutes, ultraviolet light of 150 mJ / cm ² is irradiated through a photomask, development is performed using a 0.1 wt% aqueous solution of tetramethylammonium hydride for 60 seconds, and after washing with water, 200 ° C. By performing post-baking for a long time, a red colored layer 103 is formed. The developed red coloring layer 103 has a stripe shape arranged every two rows for a plurality of pixel regions arranged in a matrix, and has a shape having a contact hole corresponding to each pixel region. (FIG. 3B).

By repeating the same steps, the blue colored layer 10
3 and the green colored layer 103 are formed in pixel regions in different columns. Then, ITO was sputtered for 100n.
The pixel electrode 104 is formed by forming a film having a thickness of m and patterning it into a shape corresponding to each pixel region. The pixel electrode 104 is connected to the source electrode 115S via a contact hole formed in the coloring layer 103. Here, the pixel electrode 10
No. 4 is formed by overlapping its end with the scanning line 113L and the signal line 115L. Further, the reflection layer 102 is formed in advance in a part of the pixel region, and the pixel electrode 104 has a portion overlapping the reflection layer 102 and a portion not overlapping. Then, polyimide is printed so as to cover the pixel electrodes 104, and a rubbing process is performed to form an alignment film 105, thereby obtaining the array substrate 1 (FIG. 3C). Next, as a method of manufacturing the opposing substrate, a light-transmitting glass substrate 201 having a thickness of 0.7 mm having a light-transmitting property is formed on one main surface of the glass substrate 201 by a sputtering method.
A counter electrode 202 is formed by forming a film of TO to a thickness of 100 nm. Further, a rubbing treatment is performed by printing polyimide thereon, and an orientation film 203 is formed to obtain the counter substrate 2. Further, a sealing material made of epoxy resin is formed in a peripheral region of the counter substrate 2 created as described above.
At this time, a sealing material is not formed only at an inlet for injecting liquid crystal later. Then, the opposing substrate 2 and the array substrate 1 are bonded to each other with one main surface side, that is, the side on which the alignment films 203 and 105 are formed, and heated to cure the sealing material, thereby creating an empty cell. I do.

Next, the empty cell is placed in a vacuum vessel, and the interior of the vacuum vessel is returned to the atmospheric pressure with the injection port where no sealing material is formed being immersed in the liquid crystal. Inject. When the injection is completed, a sealing material made of an ultraviolet curable resin is applied to the injection port, and the liquid crystal cell is obtained by irradiating ultraviolet rays and sealing. Then, λ / 4 plates 107 and 205 are provided on both sides of the liquid crystal cell, that is, on the back side of the glass substrate 101 and the glass substrate 201, respectively, and the polarizing plates 106 and 204 are further provided outside the plates so as to satisfy the above-described condition in the optical axis direction. paste. Finally, the illumination device 4 is arranged behind the array substrate 1 to obtain a liquid crystal display device. Further, since the coloring layer 103 is formed on the array substrate 1 in the transflective liquid crystal display device, the alignment margin between the array substrate 1 and the counter substrate 2 is widened, and a liquid crystal display device with low manufacturing cost is obtained. be able to. Also, the reflection layer 1
Since 02 is integrally formed at the same time as the source electrode 115S, the drain electrode 115D, and the signal line 115L, a transflective liquid crystal display device can be obtained without increasing the number of manufacturing steps. Further, the end of the pixel electrode 104 is connected to the scanning line 113L.
In addition, since the pixel region is superimposed on the signal line 115L, the pixel region can be used to the maximum extent, and high-luminance display can be performed.

Further, since the reflective layer 102 is divided and disposed, the display in the reflection mode and the display in the transmission mode are distributed in a well-balanced manner in the pixel area, and high quality is obtained even when the display intensity in both modes is different. Display can be performed.
In the present embodiment, the reflection layer 102 is divided into two, but is not limited to two and may be divided into more. Further, the material of the reflection layer 102 is not limited to aluminum, and chromium, silver, or the like can be used. Further, the reflective layer 102 is formed integrally with the source electrode 115S, the drain electrode 115D, and the signal line 115L, but may be formed integrally with the gate electrode 113 and the scanning line 113L. Although the area occupied by the reflective layer 102 in the pixel region is set to 50%, the ratio may be changed as appropriate. In order to utilize both the reflection mode and the transmission mode, the range is preferably about 10% to 90%. Although the coplanar thin film transistor 120 made of polycrystalline silicon is used as the switching element, for example, an inverted staggered thin film transistor made of polycrystalline silicon or amorphous silicon can be used.

[0015]

According to the present invention, a low-cost, high-luminance, transflective color liquid crystal display device can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a partial plan view of the liquid crystal display device according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating a method of manufacturing an array substrate according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Array substrate 2 ... Counter substrate 3 ... Liquid crystal 4 ... Illumination device 101, 201 ... Glass substrate 102 ... Reflection layer 103 ... Coloring layer 104 ... Pixel electrode 110 ... Thin film transistor

────────────────────────────────────────────────── ─── of the front page continued (51) Int.Cl. ⁷ identification mark FI theme Court Bu (reference) G02F 1/1368 G02F 1/1368 F-term (reference) 2H048 BA45 BA47 BA48 BB02 BB44 2H049 BA02 BA07 BB03 BB63 BC22 2H091 FA02Y FA08X FA08Z FA11X FA11Z FA14Z FA41Z GA01 GA06 GA13 2H092 GA29 JA24 JA41 JA46 KA04 KA10 MA12 MA14 MA27 MA30 PA01 PA02 PA08 PA11 PA12 PA13

Claims (7)

[Claims] A translucent array substrate, a translucent opposing substrate disposed opposite to the array substrate, a liquid crystal composition disposed between the array substrate and the opposing substrate,
A liquid crystal cell comprising: a switching element and a reflection layer; a coloring layer formed over the switching element and the reflection layer, the contact layer having a contact hole; and the contact hole being formed on the coloring layer. And a light-transmissive pixel electrode that is connected to the switching element via a reflective layer and has a region for displaying a reflective mode that is superimposed on the reflective layer and a region for displaying a transmissive mode that is not superimposed on the reflective layer. A liquid crystal cell characterized by the above-mentioned. 2. The liquid crystal cell according to claim 1, wherein the reflection layer is made of the same material as that of the switching element. 3. The array substrate has a wiring connected to the switching element, and an end of the pixel electrode partially overlaps the wiring via the coloring layer. The liquid crystal cell according to claim 1, wherein 4. The liquid crystal display device according to claim 1, wherein the reflection layer is divided into a plurality of portions and arranged. 5. A light-transmitting array substrate, a light-transmitting opposing substrate disposed opposite to the array substrate, a liquid crystal composition disposed between the array substrate and the opposing substrate,
A liquid crystal display device comprising: a liquid crystal cell having: a lighting device for illuminating the liquid crystal cell from the array substrate side; wherein the array substrate has a switching element and a reflection layer; and the switching element and the reflection layer. A colored layer having a contact hole, the colored layer having a contact hole, the region being formed on the colored layer, connected to the switching element via the contact hole, and displaying a reflective mode superimposed on the reflective layer; and A liquid crystal display device, comprising: a light-transmitting pixel electrode having a region for performing transmission mode display that is not superimposed on the reflective layer. 6. A method of manufacturing a liquid crystal cell in which one substrate and another substrate are bonded to each other and a liquid crystal is sealed in a gap between the substrates, wherein a step of forming a switching element and a reflective layer on the one substrate; Forming a colored layer material over the element and the reflective layer, patterning the colored layer material to form a colored layer having a contact hole, and forming the colored layer on the colored layer via the contact hole. Forming a pixel electrode having a light-transmitting property connected to the element and overlapping the reflective layer. 7. The method according to claim 6, wherein the reflection layer is formed simultaneously with a part of the switching element.