JP3614166B2 - Active matrix display device - Google Patents

Description

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

  Conventionally, as shown in FIG. 8, in the TFT constituting the pixel switch element of the active matrix liquid crystal display device, since the pixel electrode 19 and the data line 17 are formed in the same layer, the data line is the uppermost layer. Further, it was impossible to form a light shielding layer between the data lines and form a parting on the outer periphery of the image display area. Therefore, as shown in FIG. 9, a parting line 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.

  As a method of bonding the TFT substrate 26 and the counter substrate 22, the sealing agent 22 is cured by ultraviolet irradiation. At this time, in order to protect the TFT elements formed in the image display region 25, the UV light is applied from the counter substrate side. Irradiate light. Since the light shielding layer 27 on the counter substrate does not transmit ultraviolet light, a transparent insulating region for sealing is provided from the CF outer periphery light shielding layer 27 on the counter substrate to the end of the counter substrate in order to cure the sealing agent 24 with certainty. There must be. The transparent insulating area cannot increase the area of the light-shielding area that becomes a parting of the outer periphery of the image display area, so that alignment accuracy is required when incorporating the module into the module, which hinders simplification of mounting and cost reduction. Has a point. Further, the image display area 25 on the TFT substrate side cannot be enlarged, which hinders miniaturization such as an increase in the number of pixels and an increase in the aperture ratio, which is a ratio of the image display area transmitting the backlight light. Also has problems.

An active matrix type liquid crystal display device in which pixels having TFT elements are formed in a matrix on a transparent substrate according to the present invention has a liquid crystal between a pair of substrates, and a plurality of gates on one of the pair of substrates. An image display region having a line, a plurality of data lines, a transistor provided corresponding to an intersection of the gate line and the data line, a pixel electrode provided corresponding to the transistor, and the gate line In an active matrix type display device having a driver for driving a gate line to be driven,
A light shielding layer formed in an island shape between adjacent gate lines is provided on the one substrate between the image display region and the gate line driving driver. Further, the light shielding layer is formed of the same film as the data line. Furthermore, a light-shielding layer covering the gate line is further provided.

The active matrix liquid crystal display device of the present invention includes a liquid crystal between a pair of substrates, and a plurality of gate lines, a plurality of data lines, and the gate lines on one of the pair of substrates. An active matrix display having an image display area having a transistor provided corresponding to the intersection of data lines, a pixel electrode provided corresponding to the transistor, and a sample holder connected to the data line In the device
A light-shielding layer formed in an island shape between adjacent data lines is provided on the one substrate between the image display region and the sample holder.

  A light shielding layer was formed in an island shape by patterning into an island shape by photolithography only between adjacent data lines or adjacent gate lines. As a result, the parting region can be shielded from light, and display defects due to defects in the first interlayer insulating film and the second interlayer insulating film can be suppressed.

  A configuration diagram of a TFT substrate of the active matrix type liquid crystal display device of the present invention is shown in FIG. The image display region is clarified by forming the light shielding layer 1 on the outer periphery of the TFT substrate side pixel region 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. The TFT 2 turned on by the scanning signal writes the video signal taken in the data line into the liquid crystal cell 3. The liquid crystal is used here as dynamic memory. In general, the time constant of the liquid crystal is around 100 ms, so that a sufficient signal can be held by refreshing at a shorter cycle. Further, if a holding capacitor is added in parallel with the liquid crystal capacitor as required, the holding characteristics are further improved. As a storage capacitor configuration method, a transparent conductive film is provided under the pixel electrode, a pixel electrode is overlaid on the previous gate line, and a dedicated capacitor line is arranged in parallel with the gate line or signal line. There are methods.

  Next, the process of 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 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 by 500 to 1500 angstroms. As the channel conductive film, since a driver for driving is built in, a polycrystalline silicon that can form a CMOS structure and has a high ON / 0FF ratio of TFT is used. As a polycrystalline silicon film forming method, there is a low pressure CVD (Chemical Vapor Deposition) method in which monosilane (hereinafter referred to as SiH ₄ ) is thermally decomposed and deposited at a temperature of 550 ° C. to 650 ° C. Further, in order to further improve the ON current of the TFT, after depositing amorphous silicon as a precursor film by a plasma CVD apparatus or a low pressure CVD apparatus, thermal annealing is performed at 550 to 650 ° C. for 4 hours or more to thereby form silicon. The crystal size can be increased to 1 μm or more. In order to increase the crystal grain size, there are laser annealing such as excimer laser and argon laser in addition to thermal annealing. Next, after the polycrystalline silicon film is patterned into an island shape by photolithography, a gate insulating film 11 is formed. When a quartz substrate is used as the 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. A nitride film, HTO (High Temperature CVD Silicon 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 polycrystalline silicon has a high sheet resistance of 20Ω or more, gate scanning line delay is likely to occur when the number of pixels in the lateral direction increases. Therefore, metal compounds such as molybdenum silicide (hereinafter referred to as MoSi _X ) and tungsten silicide (hereinafter referred to as WSi _X ), chromium (hereinafter referred to as Cr), molybdenum (hereinafter referred to as Mo), lower resistance molybdenum silicide (hereinafter referred to as WSi _X ), In some cases, metal wiring such as tungsten (hereinafter referred to as W) 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 using an atmospheric pressure CVD method or a tetraethoxysilane (hereinafter referred to as TEOS) gas. In addition to the SiO ₂ film, a nitride film may be formed using a plasma CVD method. Next, in order to make the data line and the channel conductive layer 10 formed of polycrystalline silicon conductive, an opening is formed on the source region 13 to form the data line 17. As a data line material, metal wiring such as aluminum (hereinafter referred to as Al), Cr, Mo, W, or the like is performed. The pixel electrode 19 may be formed in the same layer as the data line. However, since the data line is in the uppermost layer, the light shielding layer 1 for parting the image display area cannot be formed between the data lines. In addition, when the pixel becomes higher in definition, the line and space between the data line and the pixel electrode becomes stricter due to the pattern rule, and the capacity coupling increases. As a result, the leakage current increases, causing display quality deterioration due to insufficient contrast. Therefore, in the present invention, the data line is embedded below the pixel electrode. Accordingly, it is not necessary to consider the space between the pixel electrode and the data line, the pixel electrode region can be expanded, and an opening area through which light can be transmitted can be obtained. After patterning the data lines by photolithography, a second interlayer insulating film is formed on the entire surface of the substrate. As a method for forming the second interlayer insulating film, the processing must be performed at a temperature lower than the melting temperature of the metal thin film used as the data line material. Therefore, when Al is used for the data line, it is necessary to form the insulating film at a low temperature of 450 ° C. or lower. Therefore, an insulating film is formed at a low temperature using a plasma TEOS apparatus, a plasma / ozone TEOS apparatus, an atmospheric pressure ozone TEOS apparatus, or the like.

A light shielding layer 1 is formed by depositing a metal or a metal compound on the second interlayer insulating film by sputtering or the like and patterning by photolithography. The light shielding layer can not only cut off the outer periphery of the image display area, but can also shield the data lines and gate lines in the image display area as shown in FIG. As the light shielding layer, a black organic thin film may be used in addition to a metal thin film such as Al, Cr, Mo, or W, or a metal compound thin film such as MoSi _x or WSi _x . Next, a hole is formed on the drain region 14 by wet etching or dry etching, and the pixel electrode 19 is formed by sputtering and patterned by photolithography. As the pixel electrode, indium tin oxide (hereinafter referred to as ITO) which is a transparent conductive film is used. There is no problem even if the process of the light shielding layer and the pixel electrode is reversed. Through the above process, a TFT is formed.

  Next, the configuration of the outer periphery of the image display area will be described based on examples. First, two types of structures were tried for the light shielding layer formed between the data line sample holder and the pixel. A plan view and a cross-sectional view of the first structure are shown in FIG. FIG. 4B shows a cross section taken along the line AA ′ of FIG. A first interlayer insulating film 16 is deposited on the transparent insulating substrate 9, a data wiring 17 passes through the insulating film, and a 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 the second interlayer insulating film has a defect, the data lines may be short-circuited through the light shielding film, thereby causing a vertical line defect. Since the data line is wired with a metal such as Al, it itself serves as a light shielding layer. Therefore, as shown in FIG. 5, as the second structure, the light shielding film 1 is formed in an island shape only by using the photolithography method between adjacent data lines. As a result, it is possible to greatly prevent the data lines from being short-circuited due to an insulating film defect, and display defects can be suppressed.

  Next, regarding the light shielding layer formed between the gate line driver and the pixel, two types of structures were tried in this embodiment. A plan view and a cross-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 data line structure 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 to form a lateral line defect. Therefore, as a second structure, as shown in FIG. 7, the light shielding layer 1 is formed by patterning into an island shape by photolithography between adjacent gate lines. 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 and on the gate line film 12 as shown in FIG. The metal material used in 17 is deposited in an island shape. As a result, the parting region can be shielded from light, and display defects due to defects in the first interlayer insulating film and the second interlayer insulating film can be suppressed.

  The following effects were obtained by making a parting of the outer periphery of the image display area on the TFT substrate.

  (1) As shown in FIG. 10, since the light shielding area can be expanded in the conventional seal area, the parting width is widened. As a result, the liquid crystal display device of the present invention can be provided with a sufficient alignment accuracy when it is incorporated into a module such as a television, a video movie, or a projector.

  (2) 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 is formed. The number of pixels can be increased and the aperture ratio can be improved without increasing the external size of the active matrix liquid crystal display device.

1 is a plan configuration diagram of an active matrix liquid crystal display device according to an embodiment of the present invention. FIG. 4 is a process cross-sectional view of the active matrix type liquid crystal display device showing an embodiment of the present invention until formation of a data line of a pixel TFT. FIG. 3 is a process cross-sectional view of the pixel TFT of the active matrix liquid crystal display device according to the embodiment of the present invention after FIG. The block diagram between the sample holder and image display area of the active matrix type liquid crystal display device which shows the Example of this invention. (A) is a top view. (B) is sectional drawing on the AA 'line. The block diagram between the sample holder and image display area of the active matrix type liquid crystal display device which shows the Example of this invention. (A) is a top view. (B) is sectional drawing on the BB 'line. 1 is a configuration diagram between a gate line driver and an image display area of an active matrix type liquid crystal display device according to an embodiment of the present invention. (A) is a top view. (B) is sectional drawing on CC 'line. 1 is a configuration diagram between a gate line driver and an image display area of an active matrix type liquid crystal display device according to an embodiment of the present invention. (A) is a top view. (B) is sectional drawing on the DD 'line. Sectional drawing of the pixel TFT of the conventional active matrix type liquid crystal display device. Sectional drawing of the conventional active matrix type liquid crystal display device. 1 is a cross-sectional view of an active matrix type liquid crystal display device showing an embodiment of the present invention. 1 is a cross-sectional view of an active matrix liquid crystal display device showing an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light shielding layer 2 TFT element 3 Liquid crystal cell 4 Data line drive clock signal input terminal 5 Data line drive start signal input terminal 6 Video signal input terminal 7 Gate line drive clock signal input terminal 8 Gate line drive 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 deflecting plate 22 opposite Substrate 23 Color filter 24 Sealant 25 Image display area (pixel)
26 TFT substrate 27 Opposite substrate side image display area (color filter) outer periphery light shielding layer

Claims (5)

A liquid crystal between a pair of substrates; a plurality of gate lines on one of the pair of substrates; a plurality of data lines; a transistor provided corresponding to an intersection of the gate lines and the data lines; In an active matrix type display device comprising an image display region having a pixel electrode provided corresponding to a transistor, and a gate line driving driver for driving the gate line,
On the one substrate between the image display region and the gate line driving driver, a first light shielding layer formed in an island shape so as to overlap the gate line via a first insulating film ; ,
Active matrix type, characterized by comprising a second light-shielding layer that is the between the gate lines adjacent first light-shielding layer and formed in an island shape so as to overlap via the second insulating film, the Display device.   The active matrix display device according to claim 1, wherein the first light shielding layer is made of the same film as the data line.   2. The active matrix display device according to claim 1, wherein the second light shielding layer is formed so as to shield the gate lines and the data lines in the image display area. A liquid crystal between a pair of substrates; a plurality of gate lines on one of the pair of substrates; a plurality of data lines; a transistor provided corresponding to an intersection of the gate lines and the data lines; In an active matrix type display device comprising: an image display region having a pixel electrode provided corresponding to a transistor;
The said one substrate at the outer peripheral portion of the image display region, and characterized by including the light-shielding layer formed in an island shape as the data line between the adjacent data lines overlap with an insulating film Active matrix display.   5. The active matrix display device according to claim 4, wherein the light shielding layer is formed so as to shield the gate lines and the data lines in the image display region.

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