JPH06175157A - Active matrix type liquid crystal display - Google Patents

Abstract

PURPOSE:To make an allowance in aligning precision when a liquid crystal display device is built up into a television, a video movie, a projector, etc., to simplify the packaging and to reduce a cost by forming the parting of the peripheral part of an image display region on a TFT substrate. CONSTITUTION:By forming a light shielding layer 1 on the peripheral part of the pixel region on the substrate side of a TFT (thin film transistor) in an active matrix type liquid crystal display, a parting is formed on the peripheral part of an image display region and the image display region is defined. The active matrix type liquid crystal display also incorporates a driver for driving data line and a driver for driving gate line on the same substrate as that of the pixel. The data line transmits successively a video signal fetched into a sample holder to a pixel, a scanning signal is imparted to the gate line and a TFT 2 turned on by the scanning signal writes a video signal fetched into the data line in a liquid crystal cell 3. This liquid crystal is used as a dynamic memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, a TFT which constitutes a pixel switch element of an active matrix type liquid crystal display device is shown in FIG.
As shown in, the pixel electrode 19 and the data line 17 are in the same layer as TF.
Since T was formed, the data line was the uppermost layer, and it was not possible to form a light-shielding layer between the data lines and form a parting line in the outer peripheral portion of the image display area. Therefore, as shown in FIG. 9, a parting is formed by the light shielding layer 27 on the outer peripheral portion of the color filter (hereinafter referred to as CF) 23 on the counter substrate 22.

[0003]

As a method of bonding the TFT substrate 26 and the counter substrate 22 to each other, the sealing agent 22 is cured by irradiation of ultraviolet rays. At this time, the TFT element formed in the image display area 25 is Ultraviolet light is irradiated from the counter substrate side for protection. Light-shielding layer 2 on the counter substrate
Since 7 does not transmit ultraviolet light, in order to surely cure the sealant 24, the CF outer peripheral light shielding layer 27 on the counter substrate is required.
A transparent insulating area for sealing must be provided from to the edge of the counter substrate. Since the area of the light-shielding area which is a parting of the outer peripheral portion of the image display area cannot be enlarged by the transparent insulating area, alignment accuracy is required when incorporating the module into the module, which hinders simplification of mounting and cost reduction. Have a point. Further, the image display region 25 on the TFT substrate side cannot be enlarged, which hinders miniaturization such that the number of pixels is increased and the aperture ratio, which is a ratio of transmitting light of the backlight to the image display region, cannot be improved. There are also problems.

[0004]

T is formed on the transparent substrate of the present invention.
An active matrix type liquid crystal display device in which pixels having FT elements are arranged in a matrix is characterized in that a light-shielding layer is formed on a TFT substrate so that the peripheral portion of the image display region has a parting. The light shielding layer is made of a metal, a metal compound, or a black organic thin film.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a constitutional view of a TFT substrate of an active matrix type liquid crystal display device of the present invention. The image display area is clarified by forming the light shielding layer 1 on the outer peripheral portion of the pixel area on the TFT substrate side of the active matrix type liquid crystal display device of the present invention. The active matrix type liquid crystal display device incorporates a data line driving driver and a gate line driving driver on the same substrate as the pixels. The data line sequentially transmits the video signal captured in the sample holder to the pixels. A scanning signal is applied to the gate line. TFT turned on by scanning signal
2 is the liquid crystal cell 3 for transmitting the video signal taken in the data line.
Write in. The liquid crystal is used here as a dynamic memory. Generally, the time constant of the liquid crystal is around 100 ms, so that it is possible to hold a sufficient signal by refreshing in a cycle shorter than this. Further, if a storage capacitor is added in parallel with the liquid crystal capacitor as needed, the storage characteristics will be further improved. The storage capacitor is constructed by providing a transparent conductive film under the pixel electrode, stacking the pixel electrode on the gate line in the previous stage, and arranging a dedicated capacitance line in parallel with the gate line or the signal line. There are ways.

Next, the process of manufacturing the TFT substrate of the active matrix type liquid crystal display device of the present invention will be described in detail. 2 and 3 are process cross-sectional views of the TFT substrate of the active matrix type liquid crystal display device of the present invention.

A channel conductive film 10 is formed on the transparent insulating substrate 9.
To form a film of 500 to 1500Å. As the channel conductive film, since a driving driver is incorporated, a polycrystalline silicon capable of forming a CMOS structure and having a high ON / 0FF ratio of TFT is used. As a method for forming a polycrystalline silicon film, low pressure CVD (Chemica) in which monosilane (hereinafter referred to as SiH ₄ ) is thermally decomposed and deposited at a temperature of 550 ° C. to 650 ° C.
1 Vapor Deposition) method. In order to further improve the ON current of the TFT, amorphous silicon is deposited as a precursor film by a plasma CVD apparatus or a low pressure CVD apparatus, and then thermal annealing is performed at 550 to 650 ° C. for 4 hours or more. Crystal 1μ
The particle size can be increased to m or more. In order to increase the crystal grain size, laser annealing such as excimer laser or argon laser may be used in addition to thermal annealing. Next, after the polycrystalline silicon film is patterned into an island shape by a photolithography method, a gate insulating film 11 is formed. When a quartz substrate is used as a transparent insulating substrate for the gate insulating film, a dense and highly reliable oxide film can be formed by high temperature dry oxidation using a MOS process. In addition, nitride film and H
TO (High Temperature CVD S
ilicon Dioxide Film) or the like may be used. Next, the gate line 12 is formed. Polycrystalline silicon is used as the gate line material. However, since the sheet resistance of polycrystalline silicon is as high as 20Ω or more, when the number of pixels in the horizontal direction increases, a gate scanning line delay easily occurs.
Therefore, molybdenum silicide (hereinafter referred to as M
oSi _X ) and tungsten silicide (hereinafter W)
Metal compounds such as Si _X ) and chromium (hereinafter Cr
In some cases, metal wiring such as (hereinafter, referred to as), molybdenum (hereinafter, referred to as Mo), tungsten (hereinafter, referred to as W), or the like is used. Next, the source region 13 and the drain region 14 are formed in a self-aligned manner by ion implantation using the gate line as a mask. Next, a first interlayer insulating film is formed on the entire surface of the substrate. As the first interlayer insulating film, a SiO ₂ film is formed by using a normal pressure CVD method or a tetraethoxysilane (hereinafter referred to as TEOS) gas. Besides the SiO ₂ film, a plasma CVD method may be used to form a nitride film. Next, an opening is formed in the source region 13 to electrically connect the data line and the channel conductive layer 10 formed of polycrystalline silicon, and the data line 17 is formed. As a material of the data line, metal wiring such as aluminum (hereinafter referred to as Al) or Cr, Mo, W is used. The pixel electrode 19 may be formed in the same layer as the data lines, but since the data lines are located at the uppermost layer, the light shielding layer 1 for dividing the image display area cannot be formed between the data lines. In addition, as the pixel becomes finer, the line and space between the data line and the pixel electrode becomes stricter due to the pattern rule, and the capacitive coupling becomes larger. As a result, the leak current becomes large, which causes deterioration of display quality due to insufficient contrast. Therefore, in the present invention, the data line is embedded below the pixel electrode. As a result, it is not necessary to consider the space between the pixel electrode and the data line, the pixel electrode region can be expanded, and the area of the opening for transmitting light can be increased. After patterning the data lines by photolithography, a second interlayer insulating film is formed on the entire surface of the substrate. Second
As a method for forming the interlayer insulating film, it is necessary to perform processing at a temperature equal to or lower than the melting temperature of the metal thin film used as the data line material. Therefore, when using Al for the data line, 4
It is necessary to form the insulating film at a low temperature of 50 ° C. or lower. Therefore, plasma TEOS device and plasma ozone TEOS
An insulating film is formed at a low temperature by using an apparatus, a TEOS apparatus using atmospheric pressure ozone, or the like. A metal or a metal compound is deposited on the second interlayer insulating film by a sputtering method or the like and patterned by a photolithography method to form the light shielding layer 1. The light-shielding layer is formed not only on the outer peripheral portion of the image display area but also on the outer peripheral portion of FIG.
As in (c), it is possible to shield the data lines and gate lines in the image display area from light. As the light shielding layer, A
Metal thin films such as 1, Cr, Mo, W, MoSi _X , WS
In addition to a metal compound thin film such as i _X , a black organic thin film may be used. Next, a hole is formed on the drain region 14 by wet etching or dry etching, and the pixel electrode 19 is formed into a film by a sputtering method and patterned by a photolithography method. As the pixel electrode,
Indium tin oxide, which is a transparent conductive film (hereinafter referred to as IT
(Referred to as O) or the like is used. There is no problem even if the steps of the light shielding layer and the pixel electrode are reversed. The TFT is formed by the above steps.

Next, the structure of the outer peripheral portion of the image display area will be described based on an embodiment. First, two types of structures were tried for the light-shielding layer formed between the sample holder of the data line and the pixel. A plan view and a sectional view of the first structure are shown in FIG.
FIG. 4B shows a cross section taken along the line AA ′ of FIG. The first interlayer insulating film 16 is deposited on the transparent insulating substrate 9, the data wiring 17 passes through the insulating film, and the light shielding film is deposited on the second interlayer insulating film 18. Since the light-shielding film is formed of a metal or a metal compound, when there is a defect in the second interlayer insulating film, the data lines may be short-circuited via the light-shielding film and a vertical line defect may occur. Since the data line is made of metal such as Al,
Acts as a light shielding layer. Therefore, as a second structure, FIG.
As shown in, the light shielding film 1 was formed in an island shape only between the adjacent data lines by the photolithography method. As a result, it is possible to significantly prevent the data lines from being short-circuited due to a defective insulating film, and it is possible to suppress defective display.

Next, two types of structures were tried in this embodiment for the light-shielding layer formed between the gate line driving driver and the pixel. A plan view and a sectional view of the first structure are shown in FIG. FIG. 6B shows a cross-sectional view taken along the line CC ′ of FIG. The gate line 12 is formed on the transparent insulating substrate 9, the first interlayer insulating film 16 and the second interlayer insulating film 18 are formed on the gate line, and the light shielding film 1 is formed on the uppermost layer. . Further, since the gate line is buried in the lowermost layer, a metal thin film used for the data line may be formed on the first interlayer insulating film instead of the light shielding film 1 (not shown). Similar to the structure of the data line shown in FIG. 4, in this structure, when a defect occurs in the interlayer insulating film, there is a possibility that the gate wirings are short-circuited with each other and a lateral line defect occurs. So the second
As shown in FIG. 7, the light shielding layer 1 was formed by patterning between adjacent gate lines in an island shape by photolithography. At this time, when the gate line is made of a transparent material such as polycrystalline silicon, the data line is formed on the first interlayer insulating film 16 so as to cover the gate line film 12 as shown in FIG. 7B. The metal material used in 17 is deposited in an island shape. This makes it possible to shield the parting region from light and suppress display defects due to defects in the first interlayer insulating film and the second interlayer insulating film.

[0010]

[Effects of the Invention] The following effects were obtained by forming a parting of the outer peripheral portion of the image display area on the TFT substrate.

As shown in FIG. 10, since the light-shielding region can be expanded to the conventional seal region, the parting width is widened. As a result, the liquid crystal display device of the present invention can be provided with sufficient alignment accuracy when it is incorporated in a module such as a television, a video movie, and a projector, so that the mounting can be simplified and the cost can be reduced.

As shown in FIG. 12, since the seal region can be formed on the light shielding layer 1 on the TFT substrate 26 without forming the light shielding layer 27 on the counter substrate, the image display region 25 formed on the TFT substrate can be formed. It is possible to increase the number of pixels and the aperture ratio without increasing the outer size of the active matrix type liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a plan configuration diagram of an active matrix type liquid crystal display device showing an embodiment of the present invention.

FIG. 2 is a process sectional view of forming a data line of a pixel TFT of an active matrix type liquid crystal display device showing an embodiment of the present invention.

3A and 3B are sectional views of the pixel TFT of the active matrix type liquid crystal display device showing the embodiment of the present invention, showing the step after FIG.

FIG. 4 is a configuration diagram between a sample holder and an image display area of an active matrix type liquid crystal display device showing an embodiment of the present invention. (A) is a plan view. (B) is sectional drawing on the AA 'line.

FIG. 5 is a configuration diagram between a sample holder and an image display area of an active matrix type liquid crystal display device showing an embodiment of the present invention. (A) is a plan view. (B) is sectional drawing on the BB 'line.

FIG. 6 is a configuration diagram between a driver for driving a gate line and an image display region of an active matrix type liquid crystal display device showing an embodiment of the present invention. (A) is a plan view. (B) is sectional drawing on CC 'line.

FIG. 7 is a configuration diagram between a driver for driving a gate line and an image display area of an active matrix type liquid crystal display device showing an embodiment of the present invention. (A) is a plan view. (B) is sectional drawing on the DD 'line.

FIG. 8 is a cross-sectional view of a pixel TFT of a conventional active matrix type liquid crystal display device.

FIG. 9 is a sectional view of a conventional active matrix type liquid crystal display device.

FIG. 10 is a sectional view of an active matrix type liquid crystal display device showing an embodiment of the present invention.

FIG. 11 is a sectional view of an active matrix type liquid crystal display device showing an embodiment of the present invention.

[Explanation of symbols]

1 Light-shielding layer 2 TFT element 3 Liquid crystal cell 4 Data line driving clock signal input terminal 5 Data line driving start signal input terminal 6 Video signal input terminal 7 Gate line driving clock signal input terminal 8 Gate line driving start signal input terminal 9 transparent insulating substrate 10 channel conductive layer 11 gate insulating film 12 gate line 13 source region 14 drain region 15 ion impurity 16 first interlayer insulating film 17 data line 18 second interlayer insulating film 19 pixel electrode 20 liquid crystal 21 deflector 22 facing Substrate 23 Color filter 24 Sealant 25 Image display area (pixel) 26 TFT substrate 27 Counter substrate side image display area (color filter) Peripheral light-shielding layer

Claims (2)

[Claims] 1. A light-shielding layer is formed on a TFT substrate in an active matrix type liquid crystal display device in which pixels having thin film transistor (hereinafter referred to as TFT) elements are arranged in a matrix on a transparent insulating substrate. Thus, the active matrix type liquid crystal display device is characterized in that it has a parting in the outer peripheral portion of the image display area. 2. The active matrix type liquid crystal display device according to claim 1, wherein the light shielding layer is made of a metal, a metal compound or a black organic thin film.