JP2009086118A - Liquid crystal display and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display having satisfactory display image quality by suppressing a light leakage current of a TFT. <P>SOLUTION: In the liquid crystal display provided with the TFT as a switching element, when a width of a tip part D1 of a drain electrode D opposed to a source electrode S is defined as W1 and a width of extended part D2 extended from the tip part D1 to a direction connected to a pixel electrode of the drain electrode D is defined as W2, W1>W2 is satisfied. At this time, when widths of parts of a semiconductor layer 16 protruding from the extended part D2 of the drain electrode D and an extended part S2 of the source electrode S on an outer side of a gate electrode G are defined as ΔWa and ΔWb, respectively, ΔWa≈ΔWb is preferably satisfied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a liquid crystal display device and an electronic apparatus using the liquid crystal display device. More specifically, the present invention is a liquid crystal display device using a backlight, and can be manufactured without changing the conventional manufacturing process, and the display image quality is improved by suppressing the light leakage current of the thin film transistor TFT (Thin Film Transistor). The present invention relates to a good liquid crystal display device and an electronic apparatus using the liquid crystal display device.

In general, liquid crystal display devices often use TFTs as switching elements. The TFT is formed on a transparent substrate such as a glass substrate, and amorphous silicon (a-Si) or polysilicon (p-Si) is used for a semiconductor layer used for a channel region. Among these, TFTs using a-Si are widely used because the manufacturing process can be performed at a low temperature. By the way, when a silicon thin film made of such a p-Si film or a-Si film is irradiated with light, a photocurrent caused by electron-hole pairs is generated. Therefore, a TFT using a semiconductor layer such as a p-Si film or an a-Si film in the channel region increases the leakage current when the channel region is irradiated with light, and as a result, crosstalk occurs. There is a problem that the quality of the display image is degraded due to a decrease in contrast.

Therefore, conventionally, it is formed as an array substrate using a bottom gate type (reverse stagger type) TFT in which the gate electrode is on the lower side and the channel region is on the upper side of the gate electrode, and the light from the backlight is partly on the gate electrode. The light from the backlight is made difficult to hit the channel region directly so as to be shielded from light. Further, by a light shielding film provided on the counter substrate, or TF
The channel region and its peripheral region are also shielded by a signal line made of a metal film passing over T.

However, particularly in an array substrate using a bottom gate type TFT, even if the conventional technique as described above is applied, the light incident from an oblique direction is not sufficiently shielded. Normally, the gate electrode that also functions as the lower light-shielding film has a flat source electrode and drain electrode in the upper layer, and therefore reflects incident light and enters the channel region. In this case, the light entering the channel region can be reduced by increasing the width of the gate electrode serving as a light-shielding film and separating the electrode end from the channel region. However, the parasitic capacitance due to the increased weight of the source and drain electrodes and the gate electrode is increased. Inconveniences such as increase in aperture and decrease in aperture ratio occur.

In addition, in the conventional liquid crystal display device as described above, the distance between the light shielding film and the channel region is 3
In terms of dimensions, the gate electrode, the drain electrode, the source electrode, the gate insulating film, the interlayer insulating film and the like are considerably separated. For this reason, light that is incident from an oblique direction between the light shielding film and the channel region or the reflected light is not sufficiently shielded. As a technique for solving such problems of the prior art, a liquid crystal display device having a TFT 70 as shown in FIG. 9 is already known. FIG. 9 is a schematic cross-sectional view of a portion of the TFT 70 of the liquid crystal display device disclosed in Patent Document 1 below.

The TFT 70 has a gate insulating film 72 formed so as to cover the upper part of the gate electrode G formed on the surface of the transparent substrate 71 and the surface of the transparent substrate 71. The gate insulating film 72 has a small thickness over the entire surface of the gate electrode G and is thickened from a position away from the gate electrode G. Then, a semiconductor layer 73 is formed so as to cover the surface of the gate insulating film 72 at a position corresponding to the gate electrode G, and the surface of the semiconductor layer 73 is arranged to face each other at a position corresponding to the gate electrode G. A source electrode S and a drain electrode D are formed so as to form the region 74.

In this TFT 70, the thickness of the gate insulating film 72 on the gate electrode G is the transparent substrate 7 around it.
Since the gate insulating film 72 is thinner than the upper gate insulating film 72, an inclined surface 75 is formed on the outer periphery of the gate electrode G in the gate insulating film 72. Therefore, even when external light from a backlight or the like enters the gate insulating film 72 from an oblique direction, the source electrode S and the drain electrode D formed on the inclined surface 75 of the gate insulating film 72 are separated from the TFT 70. The incident light component that finally reaches the channel region 74 can be reduced.

Further, as a configuration for reducing the photocurrent of the TFT even when the channel region is irradiated with light by means other than light shielding, the following Patent Document 2 discloses an edge portion of the semiconductor layer 81 as shown in FIG. For the purpose of reducing the leakage current generated in the above, a TFT 80 in which a gate electrode G, a source electrode S, and a drain electrode D are arranged concentrically is disclosed. FIG. 10 is an enlarged plan view of a TFT portion disclosed in Patent Document 2 below. The TFT 80 includes a semiconductor layer 81
Since the edge portion of the gate electrode G does not exist on the line connecting the source electrode S and the drain electrode D, the drain electrode D and the source electrode S are not short-circuited by the gate electrode G, so that the light leakage current can be reduced. Is.

On the other hand, in Patent Document 3 below, as shown in FIG. 11, a TFT 90 in which a source electrode S and a drain electrode D are arranged to face each other with a semiconductor layer 91 interposed on a gate electrode G. A TFT 90 is disclosed which is formed in a rod shape and is connected to a pixel electrode 92 and has a recess 94 for receiving a source electrode S and a distal end portion 93 of a drain electrode D. FIG. 11 is an enlarged plan view of the TFT portion of the liquid crystal display device disclosed in Patent Document 3 below. This TFT90
This is because the drain electrode D is formed in a rod shape so that the fluctuation of the parasitic capacitance C _GD of the TFT 90 is reduced even if the drain electrode D is formed shifted in the longitudinal direction. As a result, the display image quality of the liquid crystal display device Can be made uniform.
Japanese Patent Laid-Open No. 6-112486 Japanese Patent Laid-Open No. 8-160469 JP 2002-190605 A

In the TFT 70 of the liquid crystal display device disclosed in Patent Document 1, it is possible to prevent light that has entered the oblique direction from the backlight or the like effectively from reaching the channel region 74 without providing a light shielding film. However, in order to realize such an element structure of the TFT 70,
It is necessary to add a process for forming a recess in the gate insulating film 72, which is not preferable from the viewpoint of production efficiency.

Further, in the TFT 80 of the liquid crystal display device disclosed in Patent Document 2, leakage current generated at the edge portion of the semiconductor layer 81 can be reduced, but light leakage current caused by light irradiated on the semiconductor layer 81 is reduced. Insufficient to reduce. That is, in this TFT 80, both of the two electrodes formed concentrically can be the source electrode S and the drain electrode D. However, in particular, when the outer concentric electrode is the drain electrode D connected to the pixel electrode, the outer periphery of the drain electrode D is longer than the outer periphery of the source electrode S. Due to the carriers, the charge of the pixel electrode is changed to the drain electrode D.
Will be offset through. Therefore, there arises a problem that a desired charge cannot be held in the pixel electrode.

On the other hand, the TFT 90 of the liquid crystal display device disclosed in Patent Document 3 can achieve a certain effect for the purpose of suppressing a change in parasitic capacitance with respect to the process, but for a liquid crystal display device in recent years in which the brightness of the backlight is significantly increased. Insufficient suppression of light leakage current. That is, this T
As the shape of the drain electrode D of the FT 90, a circumferential shape, a square shape, a polygonal shape, or the like has been proposed as the shape of the tip end of the drain electrode D. In any case, the drain electrode D extending from the tip end portion 93 to the pixel electrode 92 is proposed. The line width is formed constant. Therefore, in the TFT 90, since the area of the semiconductor layer exposed outside the gate electrode G where the light from the backlight cannot be blocked by the gate electrode G is large, the light leakage current increases.

The present invention has been made to solve the above-mentioned problems of the prior art, and its object is to produce TFTs by light from a backlight or the like which can be manufactured without any change in the conventional manufacturing process.
An object of the present invention is to provide a bright liquid crystal display device in which the light leakage current is reduced and the display image quality is good.

In order to achieve the above object, a liquid crystal display device according to the present invention includes, as a switching element, a gate electrode formed on a transparent substrate, an insulating film that covers the gate electrode and the surrounding transparent substrate surface, and the gate electrode. In a liquid crystal display device comprising a thin film transistor comprising a semiconductor layer formed on a surface of an upper insulating film and a source electrode and a drain electrode arranged to face each other so as to partially overlap the semiconductor layer, the source electrode W1> W2 where W1 is the width of the extended portion extending from the front end portion of the drain electrode and W2 is the width of the extended portion extending from the front end portion of the drain electrode. It is characterized in that it has an extension portion that is the same as or narrower than the width of the opposite tip portion and the tip portion of the source electrode.

According to the liquid crystal display device of the present invention, the width of the tip of the drain electrode facing the source electrode of the TFT is W1, and the width of the extension extending from the tip of the drain electrode to the pixel electrode is W2. Then, W1> W2 is formed. Accordingly, since the width of the portion where the semiconductor layer protrudes outside the gate electrode can be narrowed, it is difficult to irradiate the semiconductor layer with external light, so that the generation of carriers due to the photoelectric effect is reduced, and the charges of the pixel electrode are reduced by this carrier. It is possible to suppress the cancellation. Therefore, according to the liquid crystal display device of the present invention, the light leakage current caused by the external light from the backlight or the like entering the channel region is reduced, and a liquid crystal display device with good display image quality can be obtained. In addition, since the area of the drain electrode located on the semiconductor layer can be reduced, the parasitic capacitance C _GD between the gate electrode and the source electrode can be reduced, so that the operation speed of the liquid crystal display device can be increased.

In the liquid crystal display device of the present invention, when the width of the portion of the semiconductor layer that protrudes from the extended portion of the drain electrode and the extended portion of the source electrode outside the gate electrode is ΔWa and ΔWb, respectively, It is preferably formed so that = ΔWb.

According to the liquid crystal display device of this aspect, it is possible to minimize a portion where the semiconductor layer protrudes from the gate electrode while securing a processing overlap margin between the semiconductor layer and the source / drain electrode. Therefore, the photocurrent generated in the protruding semiconductor layer can be suppressed.

In the liquid crystal display device of the present invention, an arc-shaped or linear recess is formed at the tip of the source electrode, and an arc-shaped or linear protrusion is formed at the tip of the drain electrode. It is preferable that the arc-shaped or linear protrusions of the drain electrode are arranged at a predetermined distance in the arc-shaped or linear recess of the source electrode. In addition, between the front-end | tip part and extension part of a drain electrode, you may connect so that a width | variety may change in step shape, or you may connect so that a width | variety may become narrow continuously.

According to the liquid crystal display device of this aspect, it is possible to reduce the variation in the parasitic capacitance between the gate electrode and the drain electrode even if there is a mask shift or the like during manufacture. Furthermore, since the length (channel width) of the portion where the periphery of the tip of the drain electrode and the source electrode face each other can be increased, the TFT
The on-state current can be increased. Therefore, according to the liquid crystal display device of this aspect, in addition to the effects of the present invention, there can be obtained a liquid crystal display device that can be operated at high speed with less variation in display image quality.

In the liquid crystal display device of the present invention, an arc-shaped or linear recess is formed at the tip of the source electrode, and an arc-shaped or linear protrusion is formed at the tip of the drain electrode. It is preferable that the arc-shaped or linear protrusions of the drain electrode are arranged at a predetermined distance in the arc-shaped or linear recess of the source electrode.

In the liquid crystal display device according to this aspect, in addition to the effects of the present invention, manufacturing is easier than in the case where the source electrode or the drain electrode has an arc shape.

Furthermore, in order to achieve the above object, an electronic apparatus according to the present invention includes any one of the liquid crystal display devices described above.

According to the electronic apparatus of the present invention, it is possible to obtain an electronic apparatus including a liquid crystal display device with excellent display image quality in which the light leakage current of the TFT is suppressed.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples and drawings. However, in the following embodiments, a TFT as a switching element in a liquid crystal display device is described in order to embody the technical idea of the present invention, and the present invention is specified as the TFT described in this embodiment. The present invention is equally applicable to other embodiments within the scope of the claims. In each drawing used for the description in this specification, each layer and each member are displayed in different scales so that each layer and each member can be recognized on the drawing. However, it is not necessarily displayed in proportion to the actual dimensions.

FIG. 1 is a schematic plan view of one pixel that is seen through the color filter layer of the liquid crystal display device of the embodiment. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is an enlarged plan view of the TFT in the III part of FIG. FIG. 4 is an enlarged plan view of a first modification of the TFT corresponding to FIG. FIG. 5 is an enlarged plan view of a second modification of the TFT corresponding to FIG. FIG. 6 is an enlarged plan view of a third modification of the TFT corresponding to FIG. FIG. 7 is an enlarged plan view of a fourth modification of the TFT corresponding to FIG. 8A is a diagram showing a personal computer equipped with the liquid crystal display device of the present invention, and FIG. 8B is a diagram showing a mobile phone equipped with the liquid crystal display device of the present invention.

First, the configuration of a transmissive liquid crystal display device according to an embodiment will be described with reference to FIGS. The liquid crystal display device 10 includes an array substrate AR and a color filter substrate CF facing each other with a liquid crystal layer interposed therebetween. The array substrate AR has a transparent substrate 11 made of, for example, a glass plate or an acrylic plate. In the display area on the transparent substrate 11, a plurality of scanning lines 12 made of a metal such as aluminum or molybdenum are formed in parallel at equal intervals, and a gate electrode G of the TFT is extended from the scanning line 12. ing. Similarly, in the display area on the transparent substrate 11, an auxiliary capacitance line 13 is formed in the approximate center between adjacent scanning lines 12 so as to be parallel to the scanning line 12, and the auxiliary capacitance line 13 includes the auxiliary capacitance line 13. Auxiliary capacitance electrode 1 made wider than
4 is formed.

A gate insulating film 15 made of silicon nitride, silicon oxide, or the like is laminated on the entire surface of the transparent substrate 11 so as to cover the scanning lines 12, the auxiliary capacitance lines 13, and the gate electrodes G. Then, a semiconductor layer 16 composed of an a-Si layer or a p-Si layer is formed on the gate electrode G via a gate insulating film 15, and a plurality of metals such as aluminum or molybdenum are formed on the gate insulating film 15. The signal lines 17 are formed so as to be orthogonal to the scanning lines 12. Further, a source electrode S of the TFT is extended from the signal line 17 so as to be in contact with the semiconductor layer 16,
Further, the drain electrode D is provided on the gate insulating film 15 so as to be in contact with the semiconductor layer 16 by using the same material as the signal line 17 and the source electrode S.

Here, a region surrounded by the scanning lines 12 and the signal lines 17 corresponds to one subpixel. The gate electrode G, the gate insulating film 15, the semiconductor layer 16, the source electrode S, and the drain electrode D constitute a TFT serving as a switching element, and this TFT is formed in each pixel.
In this case, the auxiliary capacitance of each pixel is formed by the drain electrode D and the auxiliary capacitance electrode 14. A specific configuration of the TFT in the liquid crystal display device of this embodiment will be described later.

A protective insulating film (also referred to as a passivation film) 1 made of, for example, an inorganic insulating material over the entire surface of the transparent substrate 11 so as to cover the signal lines 17, the TFTs, and the gate insulating film 15.
8 is laminated, and an interlayer film 19 (also referred to as a planarizing film) made of an organic insulating film is laminated on the protective insulating film 18 over the entire transparent substrate 11. A contact hole 20 is formed in the protective insulating film 18 and the interlayer film 19 at a position corresponding to the drain electrode D of the TFT. Further, in each pixel, a pixel electrode 21 made of, for example, ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) is formed on the surface of the contact hole 20 and the interlayer film 19, and all the pixels are formed on the surface of the pixel electrode 21. Alignment film (not shown) to cover
Are stacked.

Further, the color filter substrate CF is provided on the surface of the transparent substrate 22 made of a glass substrate, an acrylic substrate, or the like, at a position corresponding to at least the display region of the array substrate AR, for example, red (R) corresponding to each pixel. , Green (G), blue (B) color filter layer 2
3 is provided. Further, a common electrode 24 and an alignment film (not shown) are stacked on the surface of the color filter layer 23. In addition, as the color filter layer 23, a color filter layer of cyan (C), magenta (M), yellow (Y), or the like may be used in an appropriate combination. In the case of monochrome display, the color filter layer may be used. May not be provided.

The array substrate AR and the color filter substrate CF thus obtained are opposed to each other, columnar spacers (not shown) for keeping the cell gap at the peripheral portion constant at appropriate intervals are arranged, and the array substrate Sealing material around AR and color filter substrate CF (
After the liquid crystal 25 is injected between the two substrates and the holes into which the liquid crystal 25 is injected are sealed, the transmissive liquid crystal display device 10 is obtained.

Here, the configuration of the TFT of the liquid crystal display device 10 of the embodiment will be described in detail with reference to FIG. In FIG. 3, a gate insulating film (not shown) is formed on the surface of the gate electrode G, a semiconductor layer 16 is formed on the gate insulating film, and the source electrode S is partially overlapped with the semiconductor layer 16. And the drain electrode D are formed. Here, the source electrode S is
A tip portion S ₁ facing the drain electrode D is an arcuate recess, and this tip portion S ₁
From extends, it is connected to the signal line 17 via an extension portion S ₂ width narrower than the tip portion S ₁ (see FIG. 1). The drain electrode D, the shape of the tip portion D ₁ facing the source electrode S is arcuate but has a disc shape of substantially a diameter W1, the tip portion D of the disc-shaped
Extending from _1, it is connected to the pixel electrode 21 (see FIGS. 1 and 2) via an extension D ₂ having a width W2 from the tip portion D _1.

In the liquid crystal display device 10 of this embodiment, the width of the tip portion D ₁ of the source electrode S and the counter to the drain electrode D of the TFT and W1, the drain electrode D of the tip portion D ₁ from the pixel electrode 21
When the width of the extended portion D ₂ extending in a direction connecting was W2 and is formed such that W1> W2. Accordingly, since the width of the portion where the semiconductor layer 16 protrudes outside the gate electrode G can be reduced, it is difficult to irradiate this portion with external light from a backlight or the like. for that reason,
Since the generation of carriers in the semiconductor layer 16 due to the photoelectric effect is reduced and the light leakage current is reduced, it is possible to suppress the charge of the pixel electrode 21 from being canceled. Moreover, in the liquid crystal display device 10 of the embodiment, since the area of the drain electrode D located on the semiconductor layer 16 can be reduced, the parasitic capacitance C _GD between the gate electrode G and the drain electrode D can be reduced. The operation speed of the liquid crystal display device 10 is increased.

In the liquid crystal display device 10 according to the embodiment, the semiconductor layer 16 extends to the outside of the gate electrode G on the source electrode S side and the drain electrode D side. Further, on the side orthogonal to the source electrode S side and the drain electrode D, the light from the backlight is formed so as to be positioned on the gate electrode G in order to make it difficult for light from the backlight to enter the semiconductor layer 16. On the other hand, an extension D of the drain electrode D
_2, the semiconductor 16 so as to partially protrude from the extension D ₂ of the drain electrode D, and is formed so as to ride over the semiconductor layer 16 outside the gate electrode G. The width of the portion where the semiconductor layer 16 is protruded from the extended portion D ₂ of the drain electrode D and DerutaWa.

Further, the extended portion S ₂ of the source electrode S is formed so as to get over the semiconductor layer 16 outside the gate electrode G so that the semiconductor 16 partially protrudes from the extended portion S ₂ of the source electrode S. The semiconductor layer 16 is to ΔWb the width of the portion protruding from the extension portion S ₂ of the source electrode S. In the TFT of this embodiment, ΔWa = ΔWb is set. However, ΔWa and ΔWb do not necessarily have to be exactly the same value, and may be slightly different.

With such a configuration, it is possible to minimize a portion where the semiconductor layer protrudes from the gate electrode while securing a processing overlap margin between the semiconductor layer and the source / drain electrode. Therefore, the photocurrent generated in the protruding semiconductor layer can be suppressed.

Further, according to the TFT liquid crystal display device 10 of this embodiment, the source electrode S is the tip portion S ₁ facing the drain electrode D has an arc-shaped recess, the drain electrode S and the opposing portions of the width It is connected to the signal line 17 through the extension of the extension portion S ₂ of the width smaller than. The drain electrode D is the tip portion D ₁ facing the source electrode S is arcuate having a disk shape substantially the diameter W1, the extended portion of the narrower width W2 than the width W1 of the tip portion And is connected to the pixel electrode 21. With such a configuration, it is possible to suppress a variation in the parasitic capacitance C _GD between the gate electrode G and the drain electrode D even if there is a mask shift or the like during manufacturing. Furthermore, since the length (channel width) of the portion where the periphery of the drain electrode is opposed to the source electrode can be increased, the on-current of the TFT can be increased. For this reason, according to the liquid crystal display device 10 including the TFT of this embodiment, the liquid crystal display device 10 with little variation in display image quality and operable at high speed can be obtained.

As shown in FIG. 3, the TFT of the liquid crystal display device 10 of the embodiment is such that the tip portion S ₁ facing the drain electrode D of the source electrode S is an arc-shaped recess, and the source electrode of the drain electrode D Although the tip portion D ₁ to S and the counter is arcuate shows an example of using a disc-shaped substantially in diameter W1. However, the TFT that can be used in the liquid crystal display device of the present invention can be variously modified as long as the following conditions (1) and (2) are satisfied at the same time, in addition to those shown in FIG.
(1) the source electrode S and facing the drain electrode D of the width of the end portion D ₁ and W1, the width of the extended portion D ₂ from the tip portion D ₁ extending in the direction connecting the pixel electrode 21 of the drain electrode D W
When 2, the condition of W1> W2 is satisfied.
In the outer (2) the gate electrode G, when the semiconductor layer 16 has an extension portion _{D 2} and DerutaWa respective width of the portion protruding from the extension portion _{S 2} of the source electrode S and DerutaWb drain electrode D, of approximately ΔWa = ΔWb Meet the condition.

Modified examples of TFTs that can be used in the liquid crystal display device of the present invention will be described with reference to FIGS. 4 to 7, the same components as those of the TFT shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. The first modification shown in FIG. 4, while the tip portion D ₁ of the drain electrode D of the TFT of Example uses those disk shape substantially the diameter W1 is arcuate, drain tip portion D ₁ of the electrode D is an example of using those semi disk shape with a diameter W1 is arcuate. In this case, although the stepwise width between the tip portion D ₁ of the drain electrode D and the extension portion D ₂ is changed, the same effect as the case of the liquid crystal display device of Example.

The second modification shown in FIG. 5, the drain electrode D and a portion facing the source electrode S has a linear recess, the shape of the tip portion D ₁ facing the source electrode S of the drain electrode D Is a square shape having a width W1. Moreover, the tip portion D ₁ of the this drain electrode D is to the channel length is constant and is parallel to the front end portion of the source electrode S. in addition,
In the second modification, the width of the extension portion S ₂ of the source electrode S is the same as the width of the tip portion S ₁ of the source electrode S. Even in the case of the second modified example, since the above conditions (1) and (2) are satisfied at the same time, the same effects as in the case of the liquid crystal display device of the example can be obtained.

In the third modification shown in FIG. 6, in the TFT of the embodiment, the portion of the source electrode S facing the drain electrode D is linear, and the tip of the drain electrode D facing the source electrode S shape of the portion D ₁ also has a linear shape in which square shape having a width W1. Moreover, the end portion D ₁ of the this drain electrode D is to the channel length is constant and is parallel to the front end portion of the source electrode S. In addition, in the third modification, the width of the extension portion S ₂ of the source electrode S is the same as the width of the tip portion S ₁ of the source electrode S. Even in the case of the third modified example, since the above conditions (1) and (2) are satisfied at the same time, the same effects as in the case of the liquid crystal display device of the example can be obtained.

The fourth modification shown in FIG. 7, in the third modification, between the extended portion D ₂ of the drain electrode D of the tip portion D ₁ and the tip portion D narrower than _one width W2 is continuously Are connected in a tapered shape so that the width becomes narrower. Even in the case of the fourth modified example, the above (1)
And since the conditions of (2) are satisfy | filled simultaneously, there exists an effect similar to the case of the liquid crystal display device of an Example.

As described above, the example of the transmission type liquid crystal display device has been described as the embodiment and the modification of the present invention. Such a liquid crystal display device of the present invention can be used for electronic devices such as personal computers, mobile phones, and portable information terminals. 8A shows an example in which the liquid crystal display device 41 is used in the personal computer 40, and FIG. 8B shows an example in which the transflective FFS type liquid crystal display panel 46 is used in the mobile phone 45. However, these personal computers 4
Since the basic configuration of 0 and the cellular phone 45 is well known to those skilled in the art, a detailed description thereof will be omitted.

It is the schematic plan view for 1 pixel of seeing through the color filter layer of the liquid crystal display device of an Example. It is sectional drawing along the II-II line of FIG. FIG. 3 is an enlarged plan view of a TFT in a portion III in FIG. 1. FIG. 10 is an enlarged plan view of a first modification of the TFT corresponding to FIG. 3. FIG. 10 is an enlarged plan view of a second modification of the TFT corresponding to FIG. 3. FIG. 10 is an enlarged plan view of a third modification of the TFT corresponding to FIG. 3. FIG. 10 is an enlarged plan view of a fourth modification of the TFT corresponding to FIG. 3. FIG. 8A is a diagram showing a personal computer equipped with the liquid crystal display device of the present invention, and FIG. 8B is a diagram showing a mobile phone equipped with the liquid crystal display device of the present invention. It is an enlarged plan view of the TFT part of the liquid crystal display device of a prior art example. It is an enlarged plan view of a TFT portion of another conventional liquid crystal display device. It is an enlarged plan view of a TFT portion of yet another conventional liquid crystal display device.

Explanation of symbols

10: Liquid crystal display device 11: Transparent substrate 12: Scanning line 13: Auxiliary capacitance line 14: Auxiliary capacitance electrode 15: Gate insulating film 16: Semiconductor layer 17: Signal line 18: Protective insulating film 19
: Interlayer film 20: Contact hole 21: Pixel electrode 22: Transparent substrate 23: Color filter layer 24: Common electrode 25: Liquid crystal S: Source electrode S ₁ : Tip of (source electrode) S ₂ : Extension of (source electrode) Part D: Drain electrode D ₁ : Tip part (of the drain electrode) D ₂ : Extension part (of the drain electrode) AR: Array substrate CF: Color filter substrate

Claims (6)

As a switching element, a gate electrode formed on a transparent substrate, an insulating film covering the gate electrode and the surrounding transparent substrate surface, a semiconductor layer formed on the surface of the insulating film on the gate electrode, In a liquid crystal display device including a thin film transistor including a source electrode and a drain electrode arranged to face each other so as to partially overlap a semiconductor layer,
It is formed so that W1> W2, where W1 is the width of the tip portion of the drain electrode facing the source electrode and W2 is the width of the extended portion extending from the tip portion of the drain electrode. Liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the source electrode includes a tip portion facing the drain electrode and an extended portion having a width equal to or narrower than a width of the tip portion of the source electrode. Outside the gate electrode, the semiconductor layer is formed such that ΔWa = ΔWb when the widths of the extended portion of the drain electrode and the extended portion of the source electrode are ΔWa and ΔWb, respectively. The liquid crystal display device according to claim 1 or 2. An arcuate or linear recess is formed at the tip of the source electrode, an arcuate or linear protrusion is formed at the tip of the drain electrode, and the arcuate or linear protrusion of the drain electrode is 4. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is disposed at a predetermined distance in an arc-shaped or linear recess of the source electrode. Both the tip portion of the source electrode and the tip portion of the drain electrode are formed in a straight line,
4. The liquid crystal display device according to claim 1, wherein a tip portion of the source electrode and a tip portion of the drain electrode are arranged in parallel at a predetermined distance.   An electronic apparatus comprising the liquid crystal display device according to claim 1.

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