JP2002122884A - Liquid crystal display device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which off leak current during a TFT off interval can be reduced and on current during an on interval can be increased and its manufacturing method. SOLUTION: A variable color layer 52 is provided between an active layer 4 of a TFT and a TFT substrate 1. When the TFT is turned off, the layer 52 is colored to reduce the amount of light beams made incident on the active layer region so as to reduce the off leak current of the TFT. When the TFT is turned on, the layer 52 is made transparent, the on current is made larger by maximully using the light beams that are made incident. Thus, the on and the off currents can be independently optimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device equipped with an inverted staggered thin film transistor (hereinafter abbreviated as TFT) and a method of manufacturing the same, and more particularly to a liquid crystal display device which optimizes the on-current and off-leak current of the TFT. And its manufacturing method.

[0002]

2. Description of the Related Art Conventionally, the characteristics of a TFT fluctuate due to incident light. Therefore, if an attempt is made to reduce the off-leak current by changing the conditions for forming an insulating film, the on-current is also reduced. If the current is increased, the off-leakage current also increases, so neither the on-state current nor the off-leakage current is sufficient. However, when the liquid crystal display device has to make compromises at a current characteristic level that has little effect on reliability and optical characteristics Was seen a lot.

Here, the structure of a liquid crystal display device of a horizontal electric field type will be described. FIG. 9 shows a state of a TFT substrate for a display cell for one pixel, and FIG.
FIG. 4 is a plan view of the TFT substrate when viewed from above,
FIG. 9B shows a plane perpendicular to the TFT substrate passing through the cutting line AA ′ in FIG.
FIG. 3 is a cross-sectional view when a substrate (referred to as a color filter substrate facing a TFT substrate; hereinafter, referred to as a CF substrate) is cut.

A comb-like electrode for generating an electric field substantially parallel to the surface of a first transparent substrate 101 made of a transparent insulating material such as glass is used for a TFT substrate 1 on which a TFT element is formed.
00, and the color layer material is TFT substrate 1
The description will be made on the assumption that the case is formed only on the CF substrate 200 which is the counter substrate of No. 00.

[0005] The display cell shown in FIG.
01 and the light-shielding gate electrode 102, the common electrode 122, and the silicon nitride film (Si
Nx) or the like, a first insulating film 103, an a-Si (amorphous silicon) layer 106, and an SD made of a metal such as Cr.
Electrodes (refers to source / drain electrodes, hereinafter SD
A pixel electrode 127 and a data line 137 formed simultaneously with the SD electrode 107, a protective film 108 made of a silicon nitride film (SiNx) or the like, and a polarizing plate on the other surface of the first transparent substrate 101. TF with 110
A T substrate 100 and a second substrate made of a transparent insulating material such as glass.
The black matrix 211 on one surface of the transparent substrate 201 and the second transparent substrate 201, the color layer 213, the second insulating film 214 made of a silicon nitride film (SiNx) and the like, and the other surface of the second transparent substrate 201 on the other surface Conductive film 215, polarizing plate 21
And a CF substrate 200 having an alignment film 6 formed on the uppermost surface of each substrate by printing an alignment film by a method such as offset printing.

The thus obtained TFT substrate 100 and CF
The alignment film of the substrate 200 is rubbed as an alignment film 117, alignment molecules of the alignment film are arranged in a predetermined direction, a cell gap material is sandwiched between the two substrates so as to have a predetermined interval, and a liquid crystal is formed in the gap. 118 is sealed.

Further, a comb-shaped pixel electrode 12 for effectively generating an electric field in a lateral direction with respect to the surface of the TFT substrate 100.
The distance between 7 and common electrode 122 is set to about 7 μm.

The thicknesses of the polarizing plates 110 and 216 are set to about 0.2 mm. The conductive film 215 is set to a thickness of about 50 nm. The first transparent substrate and the second transparent substrate are set to a thickness of about 0.7 mm.
The black matrix 211 is set to a thickness of about 1 μm. The color layer 213 is set to a thickness of about 1 μm. The thickness of the second insulating film 214 is set to a thickness of about 1 μm. The orientation film 117 is set to a thickness of about 50 nm. The data line 137 and the pixel electrode 127 are set to a thickness of 200 nm. The first insulating film (gate insulating film) 103 is set to a thickness of about 500 nm. The protective film 108 is set to a thickness of about 300 nm. The common electrode 122 is set to a thickness of about 400 nm. Also, the thickness (cell gap) of the liquid crystal 118
3. arranges the spacers in the cell at an appropriate distribution density,
It is set to 5 μm.

In the liquid crystal panel thus obtained, the transmission axis of the polarizing plate 110 of the TFT substrate 100 is made coincident with the alignment direction of the liquid crystal specified by the rubbing method, and the CF is used.
A polarizing plate 216 having an absorption axis orthogonal to that of the TFT substrate 100 is attached to the substrate 200, and light 156 is applied to the TFT substrate 1.
By irradiating from the 00 side and giving a potential difference freely between the pixel electrode 127 and the common electrode 122, full-color display from black display to white display can be performed.

Next, the TFT substrate 1 shown in FIG.
FIGS. 10 and 11 show a manufacturing method for forming the TFT No. 00 as a cross-sectional view taken along the line BB ′ of FIG. 9A.

First, a light-shielding gate electrode 102 made of Cr or the like is formed on the first transparent substrate 101. At this time, a common electrode 122 is simultaneously formed on another region of the first transparent substrate 101 (FIG. a)).

Next, a silicon oxide film and a silicon nitride film (SiNx) are sequentially deposited on the entire surface of the first transparent substrate 101 to form a first insulating film 103. Further, an a-Si film 104 is formed.
An n ⁺ -type a-Si film 105 is sequentially deposited, and the n ⁺ -type a-Si film and the a-Si film are patterned into the same pattern to form an a-
An a- layer comprising an Si film 104 and an n ⁺ type a-Si film 105;
An Si layer 106 is formed (FIG. 10B).

Next, a metal film such as Cr is deposited on the entire surface of the first transparent substrate 101 so as to cover the a-Si layer 106, and is patterned to form the SD electrode 107. At this time, the SD electrode 107 A pixel electrode 127 as an extension,
Data lines 137 are formed on other areas. Pixel electrode 1
27, as shown in FIG. 9A, the first transparent substrate 10 is formed by forming parallel electrodes with a common electrode 122 formed below and applying a voltage between the electrodes.
A substantially parallel electric field is generated on the surface of the first surface. SD electrode 10
7 is formed, using the pattern of the SD electrode 107 as a mask, the n ⁺ -type a-Si
N ⁺ type a-Si so that at least the film 105 is removed.
The film 104 is etched (FIG. 10C).

Next, a protective film 108 made of a silicon nitride film covering the SD electrode 107, the pixel electrode 127 and the a-Si layer 106 is deposited, and the common electrode 122 and the pixel electrode 127 are deposited.
Then, a protective film 108 is formed thereon (FIG. 11A).

Finally, the alignment film 11 is formed on the protective film 108.
7, a polarizing plate 110 is formed on the back surface of the first transparent substrate 101 (the surface of the first transparent substrate 101 on which the TFT is not formed is referred to as the back surface).
The T substrate is completed (FIG. 11B). In the color display of the liquid crystal display device, as shown in FIG.
This is performed by irradiating the CF substrate 200 facing the T substrate 100. Upon irradiation with the light 156, the characteristics of the TFT of the TFT substrate 100 formed as described above fluctuate due to incident light.

That is, when light enters the a-Si layer 106 in a region not shielded by the light-shielding gate electrode 102 of the TFT, carriers are generated in the a-Si layer 106, and
The source-drain current.

In order to prevent this phenomenon, if the light path to the a-Si layer 106 is to be cut off as widely as possible in order to reduce the off-leak current of the TFT, the on-current also decreases, and conversely, the a-Si layer If the on-current is increased by increasing the incident light area as much as possible by limiting the light-shielding portion 106 to only the active region to increase the on-current, neither the on-current nor the off-leak current is sufficient. In many cases, a compromise has to be made at a current characteristic level that does not affect reliability or optical characteristics as a display device.

[0018]

One of the methods for solving this problem is disclosed in Japanese Unexamined Patent Publication No. Sho 62-235983, in which a transparent electrode is formed on a channel portion of a reverse staggered TFT, and a voltage is applied to the transparent electrode. The on-current is increased and the off-leakage current is reduced by controlling the incidence of light from the counter substrate side by rotating the liquid crystal positioned above the applied liquid crystal.

However, in this method, no measures are taken against light irradiation from the back surface of the TFT substrate.

The present invention controls the incidence of light from the back of the TFT substrate, which is the main cause of the incidence of light on the TFT, from the viewpoint of the amount of incident light and light energy, thereby reducing the off-leak current when the TFT is off and simultaneously turning it on. It is an object of the present invention to provide a liquid crystal display device capable of increasing an on-state current at the time and a method of manufacturing the same.

[0021]

According to the present invention, there is provided a liquid crystal display device comprising a transparent substrate and an active element formed thereon, wherein the transparent substrate is formed in a direction opposite to the active element with respect to the transparent substrate. What is claimed is: 1. A liquid crystal display device which performs color display by irradiating light toward a substrate, wherein a transparent switch electrode formed on the transparent substrate and a colored state formed in contact with the transparent switch electrode are variable. Having a colored layer,
The variable coloring layer is disposed between the transparent switch electrode and a light-shielding gate electrode that constitutes the active element, and causes a potential difference between the gate electrode and the transparent switch electrode to generate the variable coloring layer. The basic configuration is to control the incidence of light on the active layer constituting the active element by changing the colored state of the active element. The liquid crystal display device of the present invention employs the following application modes.

First, control of light incidence on the active layer is as follows:
It is performed by changing the amount of light incident on the active layer by passing light through the variable coloring layer, or controlling the incidence of light on the active layer is performed by passing light through the variable coloring layer. This is performed by changing the light energy of light incident on the active layer.

Further, the gate electrode has a transparent gate electrode which is at least in contact with each other on a plane substantially parallel to the surface of the transparent substrate.

Further, the variable coloring layer is formed in a shape that at least partially overlaps with the active layer region other than the overlapping region with the gate electrode in the active layer.

Next, in the method for manufacturing a liquid crystal display device according to the present invention, a step of depositing a transparent conductive film on a transparent substrate and patterning the transparent conductive film to form a transparent switch electrode; Depositing a variable coloring material covering the transparent switch electrode, patterning the variable coloring material to form a variable coloring layer on the transparent switch electrode in a pattern substantially the same as the transparent switch electrode; and Depositing a first insulating film covering the electrode and the variable coloring layer on the transparent substrate; and a light-shielding gate electrode and a transparent gate on the first insulating film and located above the variable coloring layer. Forming electrodes so as to be in contact with each other at least in a plane substantially parallel to the plane of the transparent substrate; and a second insulating film covering the light-shielding gate electrode and the transparent gate electrode Depositing a semiconductor film on the first insulating film, patterning the semiconductor film on the second insulating film, and forming an active layer made of a semiconductor film above the light-shielding gate electrode. Forming the variable colored layer in a shape that at least partially overlaps the active layer region of the active layer other than the overlapping region with the light-shielding gate electrode. It is.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described.
Since the focus is on the incidence of light on the Si film, the description will be focused on the TFT.

First, a first embodiment of the present invention will be described with reference to FIG. The present invention shows the basic structure in the first embodiment. Here, FIG.
FIG. 2 is a plan view of one pixel of a TFT substrate of a liquid crystal display device,
FIG. 1B is a cross-sectional view taken along the line CC ′ of FIG. Further, the present invention relates to an amorphous silicon (a-Si) layer which is an active layer of a TFT, and the configuration of other portions is the same as that shown in FIG. The sectional view is a
-It focuses on the Si layer and the structure above and below it.

First, on the first transparent substrate 1, a transparent switch electrode 51 and a variable coloring layer 52 thereon are formed.
Further, a light-shielding gate electrode 2 is formed above the transparent switch electrode 51 and the variable coloring layer 52, and a transparent gate electrode 53 as an auxiliary gate electrode having the same electric potential as the light-shielding gate electrode 2 is formed. Is done. Here, the transparent switch electrode 51 is formed in parallel with the light-shielding gate electrode 2, led out to an external connection terminal at an end of the first transparent substrate 1, and applied with a predetermined voltage. Although the transparent switch electrode 51 is formed to have the same width as the variable coloring layer 52 in the drawing, the transparent switch electrode 51 may be formed to include the variable coloring layer 52 in a plane.

The light-shielding gate electrode 2 and the transparent gate electrode 53 integrally form a gate electrode 54, and a voltage is applied between the gate electrode 54 and the opposing transparent switch electrode 51 to thereby form a gate electrode 54 therebetween. This causes an electric field to be generated.

Therefore, the variable coloring layer 52 is sandwiched between the transparent switch electrode 51 and the gate electrode 54, and an electric field generated by applying a voltage between the gate electrode 54 and the transparent switch electrode 51. Will be affected.

In the present embodiment, the transparent gate electrode 53 is formed so as to cover the light-shielding gate electrode 2, but the transparent gate electrode 53 is laid below (FIG. 8A). It is clear that the light-shielding gate electrode 2 may be formed in the first step.

Next, the gate electrode 54 is covered with the first insulating film 3.
Then, a TFT is formed above the gate electrode 54.
a-Si film 4, n⁺A type a-Si film 5 is deposited, and
A-Si film 4 and n⁺Consisting of a type a-Si film 5
An a-Si layer 6 is formed, and an SD electrode 7 is formed thereon.
And n in the opening using the SD electrode 7 as a mask. ⁺
The entirety of the mold a-Si film 5 and a part of the a-Si film 4 are removed.
Forming a channel portion 58 to complete the thin film transistor.
Let it run. The top of the TFT is covered with a protective film 8 and further aligned.
A film 17 is formed.

The operation of the first embodiment can be described as follows.

Basically, as described above, by applying a voltage between the gate electrode 54 and the transparent switch electrode 51, an electric field is generated between them, and the transparent switch electrode 51 and the gate electrode 54 The coloring state of the variable coloring layer 52 interposed therebetween is changed, and light 56 from the back surface of the first transparent substrate 1 (here, the side on which the TFT is formed is referred to as the front surface side of the transparent substrate) is emitted from the TFT. The degree of incidence on the a-Si layer 6 constituting the active layer is controlled. The degree of incidence of the light referred to here is the light a-Si
It refers to the intensity of incident light on the layer 6, the incident energy of light on the a-Si layer 6, or a combination thereof.

Next, to give an example in which the area of light incident on the a-Si layer 6 is changed, the variable coloring layer 52 can take various pattern forms. Here, it is sufficient to show the patterns of the light-shielding gate electrode 2, the a-Si layer 6, and the SD electrode 7 in addition to the variable coloring layer 52. 52 are shown in FIG.

The variable colored layer referred to here causes a potential difference between the gate electrode 54 and the transparent switch electrode 51 sandwiching the variable colored layer to generate an electric field between the gate electrode 54 and the transparent switch electrode 51, 3 has a role of changing the light transmittance of the variable colored layer, and as a first case, an electric field is generated between the gate electrode 54 and the transparent switch electrode 51, thereby the light of FIG. The intensity of light passing through the variable colored layer is changed as shown by the wavelength dependence of the transmittance. Ideally, the case where the color is changed from transparent to black, and in the second case, the gate electrode 5
4 and the transparent switch electrode 51, the variable colored layer is changed from blue to red as shown in the wavelength dependence of light transmittance in FIG.
That is, there is a case where the energy of the transmitted light is reduced according to the following expression: hν = hc / λ (h is Planck's constant, ν is light energy, and λ is light wavelength).

Of course, as another case, when changing the color of the variable colored layer from a color other than black to black, the variable colored layer is formed of a mixture of a plurality of dyes instead of a single dye. Various modifications are conceivable, such as when changing between them.

The variable coloring layer 521 shown in FIG. 2A has a rectangular pattern, and when it is in a transparent state, the light to the a-Si layer 6 is shielded only by the light-shielding gate electrode 2 to be in a light-shielding state. In this case, the light to the a-Si layer 6 is shielded with a larger area than the light-shielding gate electrode 2.

Here, the variable coloring layer 521 has a pattern including the a-Si layer 6 in both the channel width direction and the channel length direction. However, the variable coloring layer 521 does not include the a-Si layer 6 in the channel length direction. Even if the pattern includes at least the conductive gate electrode 2 in the channel length direction, the light shielding effect in the light shielding mode can be obtained.

The variable coloring layer 522 shown in FIG. 2B is a dog-bone-shaped pattern.
It is formed apart from the SD electrode 7 and partially overlaps the end of the a-Si layer 6.

Also in this case, the variable coloring layer 522
The longest part in the channel length direction has a pattern longer than the a-Si layer 6, but the a-S
Even if it is shorter than the i-layer 6, if it is at least longer than the length of the light-shielding gate electrode 2 in the channel length direction, a light-shielding effect in the light-shielding mode can be obtained.

The variable coloring layer 523 shown in FIG. 2C is a dog-bone-shaped pattern.
It is formed so as to be fitted while partially overlapping with the SD electrode 7.

Also in this case, the variable coloring layer 523
The longest portion in the channel length direction may not necessarily be longer than the a-Si layer 6 in the channel length direction, as in FIG.

FIG. 2 shows three examples of the pattern of the a-Si layer of the variable coloring layer and the light-shielding gate electrode. However, the pattern of the variable coloring layer is different from that of FIG. The light-shielding effect in the light-shielding mode can be obtained even with a shape that covers only a part of the a-Si layer region other than the overlapping region with the light-shielding gate electrode.

Next, a voltage is applied between the gate electrode 54 and the transparent switch electrode 51 to change the coloring state of the variable coloring layer 52 sandwiched between the transparent switch electrode 51 and the gate electrode 54. 4 and 5 show typical applied voltage patterns.

The applied voltage pattern shown in FIG. 4A is the simplest and ideal applied voltage timing chart, in which the voltage between the gate electrode 54 and the transparent switch electrode 51 is changed at a certain timing, for example. The variable color layer 52 is made transparent to increase the ON current by setting it to zero during a predetermined time during which the TFT is turned on, and the voltage of V is applied during other times, for example, during the time when the TFT is turned off. Colored layer 5
2 is used as a light shielding property to reduce off-leakage. Of course, the voltage between the gate electrode 54 and the transparent switch electrode 51 is set to zero at a certain timing for a predetermined time t, and the variable coloring layer 5
The case where 2 is made to have a light-shielding property (that is, the case where transparency and light-shielding are opposite to the present description under the same voltage application state) is also considered as another application form, and the application form in the opposite state is described below. The same holds true for.

The applied voltage pattern shown in FIG. 4B is a timing chart of the applied voltage when the colored state can be made sufficient only after a large electric field is applied to the variable colored layer 52. Transparent switch electrode 51
At a certain timing as a small voltage ΔV that is not zero for a predetermined time t, the variable coloring layer 52 is made transparent. At other times, a voltage of V + ΔV is applied to change the variable coloring layer 52. Light-shielding.

The applied voltage pattern shown in FIG. 4C is a timing chart of the applied voltage when it takes time to color the variable coloring layer 52 in a normal electric field. The voltage between the gate electrode 54 and the transparent switch electrode 51 is shown in FIG. Is set to zero for a predetermined time t at a certain timing, the variable coloring layer 52 is made transparent, and then the gate electrode 54 and the transparent switch electrode 51 are shifted by ΔT during the initial time when the variable coloring layer 52 is colored. Is easily colored as V + ΔV, and Δ
After the lapse of T, the variable coloring layer 52 is made light-blocking by applying a voltage of V.

The applied voltage pattern of FIG. 5A is an applied voltage timing chart in the case where it takes time to decolorize the variable colored layer 52 from a light-shielding property to a transparent one in a normal electric field. The time when the voltage between the transparent switch electrode 51 and the transparent switch electrode 51 becomes zero at a certain timing is t + Δt.
When the variable coloring layer 52 is made transparent by making it longer by Δt than usual, and then the variable coloring layer 52 is colored, the distance between the gate electrode 54 and the transparent switch electrode 51 is reduced so as to shorten the time until coloring. Variable voltage layer 5 with voltage V + ΔV
2 is light-shielding.

The applied voltage pattern shown in FIG. 5B shows that the variable colored layer 52 shifts from transparent to light-shielding, then shifts from transparent to a colored layer other than light-shielding (black), and then changes from the first transparent layer. 9 is an applied voltage timing chart in a case where a pattern that shifts to a light shielding property is repeated. First, the gate electrode 54
At a certain timing, the voltage between the transparent switch electrode 51 and the transparent switch electrode 51 is set to zero for a predetermined time t to make the variable colored layer 52 transparent. To make the variable coloring layer 52 light-shielding, and then to zero for t to make the variable coloring layer 52 transparent, and then apply a predetermined voltage having a polarity opposite to that of the transparent switch electrode 51 to the gate electrode 54. By applying V, it is colored in a color other than black, such as red, blue, or the like (in this example, V was used, but a voltage different from V may be used). After that, returning to the first cycle in which the variable coloring layer 52 is made transparent and light-shielding, the above-described voltage application chart is repeated.

The applied voltage timing chart shown in FIG. 5B is an example, and it goes without saying that the variable coloring layer 52 may be colored at various timings in various colors other than black. .

Next, a manufacturing method for obtaining the liquid crystal display device of the first embodiment shown in FIG.
A description will be given with reference to FIGS. 6 and 7 using a cross-sectional view of the same portion as the cross-sectional view near the TFT shown in FIG.

First, an ITO film is formed on the surface of the first transparent substrate 1, and the ITO film is patterned by using a photoresist technique, thereby forming a transparent switch electrode 51 on the surface of the first transparent substrate 1 (FIG. 6 (a)). )).

Next, on the surface of the first transparent substrate 1 on which the transparent switch electrode 51 is formed, an EC (Electro-electrode) represented by amorphous tungsten oxide (a-WO ₃ ) is formed.
An EC thin film 55 made of a material (hereinafter, abbreviated as EC) is formed by a vacuum evaporation method, a sputtering method, an electrolytic deposition method, an anodic oxidation method, or the like (FIG. 6).
(B)).

Subsequently, the EC thin film 55 is patterned by using a photoresist technique, and the bottom surface is transparent switch electrode 5.
The variable coloring layer 52 is formed so as to be in contact with the upper surface of the substrate 1 (FIG. 6C).

Next, a Ta ₂ O ₅ film 57 as a solid electrolyte film is formed on the surface of the first transparent substrate 1 on which the transparent switch electrode 51 and the variable coloring layer 52 are formed so that the surface is substantially flat. (FIG. 7A).

Next, after a Cr film is formed on the Ta ₂ O ₅ film 57, the Cr film is patterned by using a photoresist technique to form the light-shielding gate electrode 2 and the common electrode 22. An overlying ITO film is formed, and a transparent gate electrode 53 is formed so as to include at least a region facing the transparent switch electrode 51. At this time, the light-shielding gate electrode 2 and the transparent gate electrode 53 are in contact with each other and integrally form the gate electrode 54 (FIG. 7B).

Next, a first insulating film 3 made of a silicon oxide film and a silicon nitride film is deposited on the surface of the Ta ₂ O ₅ film 57 on which the light-shielding gate electrode 2 and the transparent gate electrode 53 are formed. A-Si according to a manufacturing method similar to that described above.
A-Si layer 6 comprising film 4 and n ⁺ -type a-Si film 5;
The D electrode 7 and the pixel electrode 27, the channel portion 58, the protective film 8, and the alignment film 17 (a polarizing plate is also formed subsequently, but not shown here) are sequentially formed to complete the TFT (FIG. c)).

By the above manufacturing method, a TFT having a variable coloring layer can be obtained.

In the manufacturing method described above, the EC thin film 5
5, a-WO to other inorganic EC film typified by _3, the organic EC such as a conductive polymer film containing dispersed viologen
A thin film can also be used.

Next, a liquid crystal display device according to a second embodiment of the present invention is shown in FIG. In the second embodiment,
The difference from the first embodiment is that the variable coloring layer 72 itself is used as the insulating flattening film without forming the Ta ₂ O ₅ film which is the insulating flattening film of the first embodiment. With such a structure, the manufacturing process can be simplified as compared with the first embodiment.

Next, a liquid crystal display device according to a third embodiment of the present invention is shown in a sectional view in FIG. In a third embodiment,
The light-shielding gate electrode and the transparent gate electrode of the first embodiment are turned upside down to form a transparent gate electrode 63 and a light-shielding gate electrode 62, respectively. The light-shielding gate electrode 62 of the third embodiment is closer to the a-Si layer 6 in the vertical direction than the light-shielding gate electrode 52 of the first embodiment. The effect of blocking light can be enhanced.

Further, the transparent gate electrode is not always necessary, and it is possible to apply an electric field to the variable coloring layer only with the light-shielding gate electrode.

[0064]

As described above, according to the liquid crystal display device and the method of manufacturing the same of the present invention, the inverted staggered T
Providing a variable colored layer between the FT active layer and the TFT substrate,
When the TFT is off, the variable coloring layer is colored to eliminate light from entering the active layer region that is not blocked by the light-shielding gate electrode.
Alternatively, by reducing the light energy of light, T
When the TFT is on, the off-leak current of the FT is made small, and the variable coloring layer is made transparent to make full use of light incident on the active layer region which is not blocked by the light-shielding gate electrode of the TFT. Can be increased, and the on-current and the off-leak current can be independently optimized.

[Brief description of the drawings]

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

FIG. 2 is a layout diagram of a variable coloring layer pattern of the present invention.

FIG. 3 is a graph showing the wavelength dependence of the light transmittance of the variable coloring layer of the present invention.

FIG. 4 is a voltage application timing chart for changing the color state of the variable coloring layer of the present invention.

FIG. 5 is another voltage application timing chart for changing the color state of the variable coloring layer of the present invention.

FIG. 6 is a cross-sectional view illustrating a method for manufacturing the liquid crystal display device according to the first embodiment of the present invention in the order of manufacturing steps.

FIG. 7 is a cross-sectional view showing a manufacturing step following FIG. 6;

FIG. 8 is a sectional view of a liquid crystal display device according to second and third embodiments of the present invention.

FIG. 9 is a plan view and a cross-sectional view of a conventional liquid crystal display device.

FIG. 10 is a cross-sectional view showing a conventional method for manufacturing a liquid crystal display device in the order of manufacturing steps.

FIG. 11 is a cross-sectional view showing a manufacturing step following FIG. 10;

[Explanation of symbols]

Reference Signs List 1, 101 First transparent substrate 2, 62, 102 Light-shielding gate electrode 3, 103 First insulating film 4, 104 a-Si film 5, 105 n ⁺ type a-Si film 6, 106 a-Si layer 7, 107 SD electrode 8,108 Protective film 10,110,216 Polarizing plate 17,117 Alignment film 22,122 Common electrode 27,127 Pixel electrode 37,137 Data line 51 Transparent switch electrode 52,521,522,523 Variable coloring layer 53, 63 Transparent gate electrode 54 Gate electrode 55 EC thin film 56, 156 Light 57 Ta ₂ O ₅ film 58, 158 Channel unit 100 TFT substrate 118 Liquid crystal 200 CF substrate 201 Second transparent substrate 211 Black matrix 213 Color layer 214 Second insulating film 215 Conductive film

Continued on the front page F-term (reference) 2H092 GA14 JA26 JA29 JA38 JA42 JA44 JB13 JB23 JB32 JB33 JB38 JB52 JB57 JB63 JB69 KA05 KA07 KA12 KA16 KA18 KB24 MA05 MA08 MA14 MA15 MA16 MA18 MA19 MA20 MA27 MA09 MA4 NA21 A25A25 PA25 BA03 BA43 CA24 DA14 EA03 EA04 EA05 EA07 EB02 GB01 5F110 AA06 AA07 AA21 CC07 DD12 DD18 EE04 EE07 EE11 EE14 GG02 GG15 HK09 HK16 HK21 NN44 NN80

Claims (7)

[Claims] 1. A color display comprising a transparent substrate and an active element formed thereon, wherein light is incident on the transparent substrate from a direction opposite to the active element toward the transparent substrate. A transparent switch electrode formed on the transparent substrate, a variable color layer formed in contact with the transparent switch electrode, the color state is variable, the variable color layer Disposed between the transparent switch electrode and the light-shielding gate electrode constituting the active element, and causing a potential difference between the gate electrode and the transparent switch electrode to change a coloring state of the variable coloring layer. The liquid crystal display device according to claim 1, wherein light incident on an active layer constituting the active element is controlled. 2. The liquid crystal display according to claim 1, wherein the control of the incidence of light on the active layer is performed by changing the amount of light incident on the active layer by passing the light through the variable coloring layer. apparatus. 3. The control of light incidence on the active layer is performed by changing light energy of light incident on the active layer by passing light through the variable coloring layer.
The liquid crystal display device according to the above. 4. The liquid crystal display device according to claim 1, wherein the gate electrode has a transparent gate electrode that is at least in contact with each other on a plane substantially parallel to the surface of the transparent substrate. 5. The variable coloring layer according to claim 1, wherein the variable coloring layer is formed in a shape at least partially overlapping an active layer region of the active layer other than an overlapping region with the gate electrode. Liquid crystal display. 6. A step of depositing a transparent conductive film on a transparent substrate, patterning the transparent conductive film to form a transparent switch electrode, and depositing a variable coloring material covering the transparent substrate and the transparent switch electrode. Patterning the variable coloring material to form a variable coloring layer on the transparent switch electrode in substantially the same pattern as the transparent switch electrode, and a first insulating film covering the transparent switch electrode and the variable coloring layer Depositing the light-shielding gate electrode and the transparent gate electrode located on the first insulating film and above the variable coloring layer substantially parallel to the surface of the transparent substrate. Forming a second insulating film covering the light-shielding gate electrode and the transparent gate electrode on the first insulating film; Depositing a semiconductor film on the second insulating film, patterning the semiconductor film, and forming an active layer made of a semiconductor film above the light-shielding gate electrode. Device manufacturing method. 7. The liquid crystal display device according to claim 6, wherein the variable coloring layer is formed in a shape at least partially overlapping an active layer region of the active layer other than an overlapping region with the light-shielding gate electrode. Production method.