JP2008191470A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the yield of a liquid crystal display device by reducing the contact defect of a light shielding layer for channel protection of a pixel TFT and a constat voltage wiring. <P>SOLUTION: The liquid crystal display device is provided with a common layer 7 which is integral with adjacent two light shielding layer lines among a plurality of the light shielding layer lines 4 and are used to connect these light shielding layer lines and a scanning line driving circuit line power source line 8 and thereby the space for installing the contact hole 15 is sufficiently assured and the designing taking the size of the contact holes, the number of installation thereof, etc., into consideration is made attainable and therefore, the contact defect of the light shielding layer line 4 and the scanning line driving circuit line power source line 8 can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an active matrix liquid crystal display device.

  2. Description of the Related Art In recent years, an active matrix type liquid crystal display device in which pixel TFTs (thin film transistors) are arranged in a matrix form as switching elements at intersections of a plurality of scanning lines and a plurality of signal lines that are arranged to cross each other on an array substrate. Is widely used as a display device for information equipment because of its excellent color development and few afterimages. In a projection type liquid crystal projector such as a projection, the liquid crystal display device is irradiated with strong light, and thus light leakage of the pixel TFT occurs in an array substrate having a top gate structure. On the other hand, a method of preventing light leakage of the TFT by irradiating light from the back side of the pixel TFT channel, that is, the counter substrate side is used.

On the other hand, the head-up display, which has been developed in recent years, projects an image on the windshield of a car. In this case, powerful backlight light is applied to the liquid crystal display device, and sunlight is applied to the liquid crystal display device through the windshield. As a result, the pixel TFTs on the array substrate are exposed to light from above and below the channel, causing a reduction in contrast ratio due to light leakage. Therefore, recently, in a head-up display, a light shielding layer is formed on the back side of the pixel TFT channel via an insulating film, and the light shielding layer is electrically connected to a constant voltage wiring to stabilize the potential of the light shielding layer and cause light leakage. A technique for preventing the occurrence of the above has been disclosed (see, for example, Patent Document 1 and Patent Document 2). In this case, the light shielding layer formed by multilayer wiring on the array substrate and the constant voltage wiring are connected through the contact hole.
Japanese Patent Laid-Open No. 11-101990 JP 2004-258671 A

  However, in the prior art, when contact failure occurs due to ESD (electrostatic discharge) or contact hole formation failure, the potential of the light shielding layer becomes unstable, so that light leakage occurs in the pixel TFT and yield decreases. .

  The present invention has been made in view of the above, and an object of the present invention is to reduce contact failure between a channel protection light-shielding layer of a pixel TFT and a constant voltage wiring and improve yield in a liquid crystal display device.

  A liquid crystal display device according to the present invention includes a plurality of scanning lines and a plurality of signal lines that are wired to cross each other, a pixel TFT disposed at each intersection of the plurality of scanning lines and the plurality of signal lines, and a pixel TFT A plurality of light shielding layer lines wired along a plurality of scanning lines and at least two adjacent light shielding layer lines among the plurality of light shielding layer lines. And a common layer for electrically connecting the line and the constant voltage wiring through the contact hole.

  In the present invention, the channel portion of the pixel TFT is shielded from light and is integrated with at least two adjacent light shielding layer lines out of the plurality of light shielding layer lines wired along the plurality of scanning lines. By providing a common layer for electrically connecting the light shielding layer line and the constant voltage wiring through the contact hole, a sufficient space for the contact hole is secured, and the size and number of the contact holes are taken into consideration. Therefore, the contact failure between the light shielding layer line and the constant voltage wiring can be reduced.

  In the common layer of the liquid crystal display device, a plurality of contact holes are dispersedly provided.

  In the present invention, it is possible to reduce the occurrence of contact hole formation defects by disposing a plurality of contact holes in the common layer.

  The constant voltage wiring in the liquid crystal display device uses, for example, a power line of a scanning line driving circuit that drives the scanning lines.

  According to the liquid crystal display device of the present invention, it is possible to reduce the contact failure between the channel protection light-shielding layer of the pixel TFT and the constant voltage wiring, and to improve the yield.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment]
The block diagram of FIG. 1 shows a schematic configuration on an array substrate of a liquid crystal display device according to an embodiment. As shown in the figure, the liquid crystal display device includes a display area 101 provided in the center, a scanning line driving circuit 102 disposed on the left side, a signal line driving circuit 103 disposed on the lower side, and an upper side. The array substrate 100 is provided with a signal line termination portion 104 disposed on the right side and a scanning line termination portion 105 disposed on the right side portion. Here, the liquid crystal display device is, for example, a head-up display that projects an image on a windshield of a car, and a backlight device (not shown) is disposed on the back side of the array substrate 100.

  In the display area 101, a plurality of scanning lines 1 and a plurality of signal lines 2 intersect with each other. A pixel TFT 3 and an auxiliary capacitor 5 are arranged as switching elements at each intersection of the plurality of scanning lines 1 and the plurality of signal lines 2. The pixel TFT 3 has a gate terminal connected to the scanning line 1, a drain terminal connected to the signal line 2, and a source terminal connected in parallel to the auxiliary capacitor 5 and a pixel electrode (not shown). A plurality of light shielding layers for shielding the channel portions of the pixel TFTs 3 are wired along the plurality of scanning lines 1 (hereinafter referred to as light shielding layer lines 4).

  The scanning line driving circuit 102 supplies a control signal to the pixel TFT through the scanning line 1 based on a power supply voltage and a timing signal supplied from the outside of the array substrate 100. The signal line driver circuit 103 supplies a video signal to the pixel TFT through the signal line 2. For example, a protective diode for terminating the scanning line 1 or the signal line 2 is disposed in the signal line termination unit 104 and the scanning line termination unit 105.

  Next, a specific configuration of one pixel will be described with reference to FIGS. The layout diagram of FIG. 2 shows one pixel in the display area 101. A pixel TFT 3 is disposed at the intersection of the scanning line 1 and the signal line 2. Here, the structure of the pixel TFT 3 is a double gate structure in order to reduce leakage current. On the back side of the scanning line 1, a light shielding layer line 4 shown by oblique lines is wired. This prevents a decrease in pixel aperture ratio.

  3 is a cross-sectional view taken along a line AA in FIG. As shown in the figure, an insulating film 10 is formed on the light shielding layer line 4. A polysilicon film is formed on the insulating film 10 as the channel 11 of the pixel TFT. A TEOS film 12 is formed on the insulating film 10 and the channel 11 of the pixel TFT, and further, the scanning line 1 is wired thereon by MoW. An insulating film 13 is formed on the TEOS film 12 and the scanning line 1, and a signal line 2 is further provided thereon. Here, the contact hole 14 penetrates the insulating film 13 and the TEOS film 12, and the signal line 2 is electrically connected to the channel 11 of the pixel TFT via the contact hole 14. Thus, in the array substrate having the top gate structure, the light shielding layer line 4 is formed on the back side of the channel 11 of the pixel TFT via the insulating film 10 to shield the channel portion of the pixel TFT 3.

  Next, a specific configuration of the light shielding layer line 4 will be described with reference to the drawings. The layout diagram of FIG. 4 shows the vicinity of the boundary between the display area 101 and the scanning line driving circuit 102. In the display area 101, the light shielding layer line 4 is wired along the scanning line 1. In the scanning line driving circuit 102, the scanning line driving circuit power supply line 8 is wired in a strip shape on the boundary side in a direction perpendicular to the direction of the light shielding layer line 4. The scanning line drive circuit power supply line 8 is a 10V system power supply line, and is mainly used in a shift register / level shifter or the like in the scan line drive circuit 102.

  Of the plurality of light shielding layer lines 4 indicated by hatching, the light shielding layer lines 4 are integrated with two adjacent light shielding layer lines 4, and the light shielding layer lines and the scanning line drive circuit power supply line 8 are electrically connected via contact holes 14 and 15. A common layer 7 is provided for connection. Here, the scanning line driving circuit power supply line 8 is used as a constant voltage wiring to which a constant voltage is supplied.

By providing the common layer 7 in this manner, a sufficient space for arranging the contact hole 15 is secured, so that it is possible to design in consideration of the size and the number of the contact holes. Here, in the common layer 7, three contact holes 15 are provided in the region between the first and second light shielding layer lines 4 and in the region between the second and third light shielding layer lines 4, respectively. It is installed.
FIG. 5 shows a cross section of the common layer 7 taken along the line BB, and FIG. 6 shows a cross section of the common layer 7 taken along the line CC. The common layer 7 and the scanning line drive circuit power supply line 8 are formed in different layers. Specifically, on the common layer 7 formed integrally with the light shielding layer line 4 and on the same layer, the insulating film 10, the TEOS film 12, the scanning line 1, the auxiliary capacitance line 6, and the like, the MoW layer 16, the insulating layer The film 13 and the scanning line driving circuit power supply line 8 are formed in order.

  In such a laminated structure, the contact hole 15 penetrates the insulating film 10 and the TEOS film 12, and the common layer 7 is connected to the MoW layer 16 through the contact hole 15. Further, the contact hole 14 penetrates the insulating film 13, and the MoW layer 16 is connected to the scanning line driving circuit power supply line 8 through the contact hole 14. With such a configuration, contact failure between the light shielding layer line 4 and the scanning line drive circuit power supply line 8 can be reduced, the potential of the light shielding layer line is stabilized, and light leakage of the pixel TFT is suppressed. Therefore, the yield can be improved.

  Therefore, according to the present embodiment, two light shielding layer lines adjacent to each other among the plurality of light shielding layer lines 4 are integrated, and the light shielding layer lines and the scanning line drive circuit power supply line 8 are connected via the contact holes. By providing the common layer 7 for connection, a sufficient space for installing the contact hole 15 is secured, and the design considering the size and number of contact holes can be made. Contact defects with the line drive circuit power supply line 8 can be reduced. Therefore, contact failure between the channel protection light-shielding layer of the pixel TFT and the constant voltage wiring can be reduced, and the yield can be improved.

[Comparative example]
Here, in order to facilitate understanding of the present embodiment, a liquid crystal display device conventionally disclosed as a comparative example will be described. The configuration of the liquid crystal display device of the comparative example has the same basic configuration as that described in this embodiment, and therefore, the following description will focus on differences.

  The layout diagram of FIG. 7 shows details in the vicinity of the boundary between the display area of the liquid crystal display device as a comparative example and the scanning line driving circuit. Here, the light shielding layer line 4 is electrically connected to the scanning line driving circuit power supply line 8 via the contact holes 14 and 15 for each line. Here, four contact holes 15 are provided for each line.

  In such a configuration, for example, when a contact hole formation failure occurs in the first light shielding layer line 4, the potential of the light shielding layer line 4 of the pixel TFT becomes floating. For this reason, the characteristics of the pixel TFT connected to the scanning line 1 in the first row may become unstable.

  Therefore, in the present embodiment, as shown in the layout diagram of FIG. 4, the contact hole 15 is provided by providing the common layer 7 integrated with two adjacent light shielding layer lines among the plurality of light shielding layer lines 4. Sufficient space for installation is secured. Here, the diameter of the contact hole 15 is made larger than that of the comparative example, and six are provided. Contact failures between the light shielding layer line 4 and the scanning line driving circuit power supply line 8 can be reduced.

  Further, in the common layer 7, three in the region between the first and second light shielding layer lines 4, and three in the region between the second and third light shielding layer lines 4. A plurality of contact holes 15 are distributed and installed. Thereby, the occurrence of contact failure between the common layer 7 and the MoW layer 16 due to the formation failure of the contact hole 15 can be reduced.

  In this embodiment, the common layer integrated with the two adjacent light shielding layer lines is connected to the constant voltage wiring. However, the present invention is not limited to this. The light shielding layer line or a common layer integrated with all the light shielding layer lines may be connected to the constant voltage wiring.

  In the present embodiment, six contact holes 15 are provided for each common layer. However, the present invention is not limited to this. For example, a common layer integrated with three adjacent light shielding layer lines is defined. When connecting to the voltage wiring, nine contact holes 15 can be provided.

  In the present embodiment, the power supply line of the scanning line driving circuit is used for the constant voltage wiring. However, the present invention is not limited to this, and the power supply line for the protective diode arranged at the scanning line termination portion is not limited to this. May be used.

  Further, in this embodiment, the light shielding layer line is configured to be wired along a plurality of scanning lines, but the present invention is not limited to this, for example, the light shielding layer line is wired along a plurality of signal lines, Even when a common layer similar to that in the above embodiment is provided and the power line of the signal line driver circuit or the power line of the protection diode at the signal line terminal is used as the constant voltage wiring, the same effect as in this embodiment can be obtained. be able to.

It is a block diagram which shows the schematic structure on the array substrate of the liquid crystal display device which concerns on one embodiment. It is a layout figure which shows the detail of one pixel of the said liquid crystal display device. It is sectional drawing of the AA part of FIG. FIG. 3 is a layout diagram showing details in the vicinity of a boundary between a display area of the liquid crystal display device and a scanning line driving circuit. It is sectional drawing of the BB part of the common layer of FIG. It is sectional drawing of CC part of the common layer of FIG. FIG. 6 is a layout diagram illustrating details in the vicinity of a boundary between a display area and a drive circuit of a liquid crystal display device as a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Scanning line 2 ... Signal line 3 ... Pixel TFT
4 ... light shielding layer 5 ... auxiliary capacitor 6 ... auxiliary capacitor line 7 ... common layer 8 ... scanning line drive circuit power supply line 10 ... insulating film 11 ... polysilicon film 12 ... TEOS film 13 ... insulating film 14 ... contact hole (interlayer)
15 ... Contact hole (light shielding layer)
16 ... MoW layer 100 ... array substrate 101 ... display region 102 ... scanning line driving circuit 103 ... signal line driving circuit 104 ... signal line termination unit 105 ... scanning line termination unit

Claims (3)

A plurality of scanning lines and a plurality of signal lines wired to cross each other;
A pixel TFT disposed at each intersection of the plurality of scanning lines and the plurality of signal lines;
A plurality of light shielding layer lines wired along the plurality of scanning lines, while shielding light from a channel portion of the pixel TFT;
A common layer that is integral with at least two adjacent light shielding layer lines among the plurality of light shielding layer lines, and electrically connects the light shielding layer lines and the constant voltage wiring via contact holes;
A liquid crystal display device comprising:   The liquid crystal display device according to claim 1, wherein a plurality of contact holes are distributed in the common layer.   The liquid crystal display device according to claim 1, wherein the constant voltage wiring is a power line of a scanning line driving circuit that drives the scanning line.

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