JP4152623B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device and a manufacturing method thereof.
[0002]
[Prior art]
An example of a basic configuration of a liquid crystal display device using a TFT as a driving element is as follows. A TFT, a scanning wiring, or a signal wiring is formed on a first transparent substrate, and a color filter is formed on a second transparent substrate. The liquid crystal is sealed in the gap with the TFT or color filter forming surface of the second transparent substrate facing inside. The TFT on the first substrate is disposed in each pixel region. The color filter on the second substrate has red (R), green (G), and blue (B) regions of color arranged in stripes for each pixel region, and each color CF is separated by black such as metal. It has a matrix configuration. The brightness, that is, the aperture ratio of the liquid crystal display device configured as described above is greatly reduced when the alignment accuracy of the first and second substrates is poor, and this influence is caused by the TFT, the scanning wiring, or the signal on the first substrate. Greater than the effect of deterioration in alignment accuracy between wires. Therefore, in addition to TFT, scanning wiring, signal wiring, etc. on the first substrate, the technology to form the color filter and black matrix previously formed on the second substrate at the same time, generally color filter-on-TFT The technology called is open to the public.
[0003]
On the other hand, as a method of widening the viewing angle of the liquid crystal display device, the liquid crystal molecules are rotated while being kept almost horizontal with the substrate, and both the pixel electrode and the common electrode for driving the liquid crystal are formed on the first substrate. An IPS (In-Plane-Switching) method in which a voltage is applied between the two electrodes to generate an electric field that is nearly horizontal with the substrate, and one of the pixel electrode and the common electrode is not processed into a comb shape. An FSS (Fringe-Field-Switching) method has been proposed in which a flat plate is formed and a tooth-like electrode is formed on the upper portion thereof via an insulating film. The FSS system is disclosed in Japanese Patent Application Laid-Open No. 11-202356.
[0004]
A method for realizing a color filter on TFT by the IPS method is disclosed in Japanese Patent Laid-Open No. 2000-111957.
[0005]
[Problems to be solved by the invention]
However, in Japanese Patent Application Laid-Open No. 2000-111957, pixel electrodes for applying an electric field to the liquid crystal layer are arranged above the color filter layer through through holes opened in the color filter layer. This through hole is formed for each pixel. However, as a result of experiments, the inventors have found a serious problem regarding mass productivity and yield that the yield drop due to clogging of the through hole is large. In the IPS display system, a through hole is opened as in Japanese Patent Application Laid-Open No. 2000-111195 because of a voltage dividing effect by a color filter layer having a low dielectric constant and a thickness that is larger than the thickness of the inorganic insulating film on the TFT. If not, a sufficient voltage cannot be applied to the liquid crystal layer, and there is a problem that the transmittance is lowered.
[0006]
Further, in Japanese Patent Application Laid-Open No. 11-202356, in order to rotate liquid crystal molecules horizontally with the first substrate, a common electrode not formed in a comb shape on the first substrate and a comb tooth via an insulating film thereon. Although a configuration in which a pixel electrode having a shape is formed is disclosed, the color filter is not formed on the first substrate, and there is no technical disclosure including problems relating to the color filter on TFT. On the other hand, Japanese Patent Application Laid-Open No. 2000-11957 discloses one method of color filter-on-TFT using the IPS method, but in the cross-sectional structure, a transparent insulating film is formed between the pixel electrode and the common electrode. As a basic configuration, the resin color layer that constitutes the color filter CF layer is configured with a predetermined thickness of red (R), green (G), and blue (B) according to the designated color scheme of each pixel. And patterned. Therefore, after forming a normal TFT, after three photo-patterning steps, the color filter layer R, G, B is formed, and then one of the pixel electrode or the common electrode is formed. In addition, a transparent insulating film is formed, and the pixel electrode or the other comb electrode of the common electrode is formed on the transparent insulating film. Further, such a long process increases the chance of alignment of exposure on the first substrate on which the TFT is formed, and when a manufacturing process that secures an alignment margin is performed, the color filter on TFT There is a problem that the original purpose of providing a bright liquid crystal display device by increasing the aperture ratio and transmittance, which are the objectives, is impaired.
[0007]
The object of the present invention is to solve the above-mentioned problems. The first object is to form a pixel electrode and a common electrode for driving a liquid crystal layer on a first glass substrate without forming a through hole for each pixel. Furthermore, another object of the present invention is to provide a TFT liquid crystal display device that also incorporates a color filter layer.
[0008]
The second purpose is to form not only TFT but also CF on the first substrate when a liquid crystal display device having a wide viewing angle is formed by rotating liquid crystal molecules horizontally on the substrate using a simple manufacturing method. The liquid crystal display device and the manufacturing method thereof are provided.
[0009]
A third object is to provide a liquid crystal display device having a high aperture ratio or transmittance and a method for manufacturing the same.
[0010]
Further objects of the present invention will become apparent herein.
[0011]
[Means for Solving the Problems]
A typical means for solving the above problems will be briefly described as follows.
[0012]
(Means 1) A first and second transparent substrates, and a liquid crystal layer sandwiched between the first and second substrates, wherein the first substrate has a plurality of video signal lines and a plurality of scanning signals. And a plurality of pixel regions formed as regions surrounded by the video signal lines and the scanning signal lines, each pixel region having at least one active element and a pixel electrode, In a liquid crystal display device having a color filter layer between liquid crystal layers, a boundary of a color filter of a pixel adjacent in a scanning signal line extending direction is positioned on the video signal line, and the boundary portion and the video signal line And a light shielding layer is formed between the color filter and the liquid crystal layer.
[0013]
This shortens the process, and by providing a color filter boundary on the video signal line and providing a light-shielding layer that shields the boundary region, a liquid crystal display device that can reduce the alignment margin and improve the aperture ratio can be realized. .
[0014]
(Means 2) A first and second transparent substrates, and a liquid crystal layer sandwiched between the first and second substrates, wherein the first substrate has a plurality of video signal lines and a plurality of scanning signals. And a plurality of pixel regions formed as regions surrounded by the video signal lines and the scanning signal lines, each pixel region having at least one active element, a pixel electrode, and a common electrode, In a liquid crystal display device having a color filter between a pixel electrode and the liquid crystal layer, the common electrode is formed in an upper layer than the color filter, the pixel electrode is formed in a lower layer than the color filter, and the color filter is the pixel The region is formed so as to overlap at least the entire surface of the pixel electrode.
[0015]
Accordingly, it is possible to provide a TFT liquid crystal display device in which a pixel electrode and a common electrode for driving a liquid crystal layer are arranged on the first glass substrate without forming a through hole for each pixel, and a color filter layer is also built in.
[0016]
(Means 3) First and second transparent substrates, and a liquid crystal layer sandwiched between the first and second substrates, wherein the first substrate has a plurality of video signal lines and a plurality of scanning signals. And a plurality of pixel regions formed as regions surrounded by the video signal lines and the scanning signal lines, each pixel region having at least one active element, a pixel electrode, and a common electrode, In the liquid crystal display device having a color filter between a pixel electrode and the liquid crystal layer, the common electrode and the pixel electrode are formed below the color filter layer, and the color filter is at least in the pixel region and in common with the pixel electrode. It is formed so as to overlap the entire surface of the electrode.
[0017]
Also in this means, a TFT liquid crystal in which a pixel electrode for driving a liquid crystal layer and a common electrode are arranged on the first glass substrate and a color filter layer is also built in without forming a through hole for each pixel similarly to the means 2. A display device can be provided.
[0018]
(Means 4) A first and second transparent substrates, and a liquid crystal layer sandwiched between the first and second substrates, and formed on at least one of the first and second substrates The first substrate has a plurality of video signal lines, a plurality of scanning signal lines, and a plurality of pixel regions formed as a region surrounded by the video signal lines and the scanning signal lines; Each pixel region includes at least one active element and a pixel electrode, and in the liquid crystal display device having a color filter layer between the pixel electrode and the liquid crystal layer, the color filter is interposed between the pixel electrode and the common electrode. The driving electric field of the liquid crystal layer is formed between the pixel electrode and the common electrode through a path that passes through both the liquid crystal layer and the color filter.
[0019]
With this arrangement, a driving electric field is applied to the liquid crystal layer sandwiched between the color filter layer and the second substrate without forming a through hole in each pixel of the color filter layer. Since no through hole is provided in the color filter, the alignment accuracy between the layers is improved, so that the aperture ratio is improved and a bright TFT liquid crystal display device can be realized.
[0020]
Further, an example of the means of the present invention will be described as follows.
[0021]
In order to apply a larger electric field to the liquid crystal layer, the pixel or common electrode formed in the color filter layer is planarly comb-shaped, the common electrode or pixel electrode under the color filter is rectangular, and at least the above-mentioned If the end of the comb electrode overlaps with the lower rectangular electrode, and the electric field strength between the common electrode and the pixel electrode is defined by the film thickness of the insulating film sandwiched between the common electrode and the pixel electrode as described above good. Further, the pixel or common electrode is formed into a comb-like shape in a plane, the common electrode or pixel electrode below the color filter is rectangular, and at least the end portion of the comb electrode overlaps the lower rectangular electrode, As described above, the color filter layer may be formed on the upper part of the insulating film so that the electric field strength between the pixel electrodes is defined by the film thickness of the insulating film sandwiched between the common electrode and the pixel electrode.
[0022]
In a liquid crystal display device that achieves another object of the present invention, at least two or more color filter layers are stacked to serve as a light-shielding film for a TFT, thereby simplifying the process.
[0023]
A liquid crystal display device that achieves another object of the present invention is a color filter having a high transmittance by separating the color filter layers along adjacent drain lines so as not to overlap each other or by separating each color pixel layer. Since the color filter layer itself can be used as an electrode, a bright TFT liquid crystal display device with a low driving voltage can be provided.
[0024]
The means for providing a bright TFT liquid crystal display device will be further described as follows.
[0025]
A first and second transparent substrate; and a liquid crystal layer sandwiched between the first and second substrates, wherein the first substrate includes a plurality of video signal lines, a plurality of scanning signal lines, and the In the liquid crystal display device having a pixel region formed as a region surrounded by a video signal line and each signal line adjacent to the scanning signal line, each pixel region having at least one active element and a pixel electrode. A liquid crystal display device comprising: a light-shielding layer and a common electrode laminated on a signal line through an insulating film, wherein the light-shielding layer is a metal, and the common electrode is a transparent conductor.
[0026]
Further, a portion of the common electrode on the video signal line is wider than the light shielding layer.
[0027]
Furthermore, the common electrode is laminated on the light shielding layer.
[0028]
Furthermore, the common electrode is laminated below the light shielding layer.
[0029]
Further, the common electrode overlaps with the light shielding layer on the video signal line, and the common electrode does not overlap with the light shielding layer in a display region between the video signal lines.
[0030]
Furthermore, the pixel electrode has a comb shape.
[0031]
Furthermore, the pixel electrode has a comb shape and is formed below the insulating film.
[0032]
Further, the insulating film is a color filter and has a boundary portion positioned on the video signal line.
[0033]
Furthermore, the insulating film is an organic film.
[0034]
Furthermore, the light shielding layer is also formed on the scanning signal line.
[0035]
Further means and advantages of the present invention will become apparent in this specification including the claims.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following examples, the semiconductor film is represented by amorphous silicon (a-Si) and the transparent conductive film is represented by ITO. However, this may be polycrystalline silicon, giant crystal silicon, or single crystal silicon. In addition, other transparent conductive films such as indium zinc oxide (IZO), InO 2, SnO 2, ZnO, a mixture thereof, or a conductive oxide containing In may be used. As names for TFT wiring, a scanning wiring is a gate wiring and a video signal wiring is a drain wiring. The TFT source and drain electrodes are referred to as a TFT electrode connected to the drain wiring side as a drain electrode, and a pixel electrode side sandwiching the TFT channel length region as a source electrode.
[0037]
[Example 1]
1 and 2 show the structure of a pixel portion of a liquid crystal display device according to the first embodiment. FIG. 1 shows a cross section taken along the line AA ′ of FIG.
[0038]
First, it demonstrates using FIG. On the first substrate SUB1 using a glass substrate, a gate wiring (gate electrode) GL made of Mo, Cr, or Al is disposed, and a gate insulating film GI made of SiN is formed so as to cover the gate wiring GL. ing. The gate wiring GL is supplied with a scanning drive voltage. A semiconductor film AS made of amorphous silicon is disposed on the gate wiring GL via a gate insulating film GI, and functions as a channel layer of a thin film transistor (TFT). Further, the drain electrode SD1 and the source electrode SD2 are arranged by Mo 2, Cr or Al through the semiconductor layer d0 doped with phosphorus at a high concentration, and the protective film PSV using SiN is formed so as to cover them. Yes. The drain electrode SD1 actually constitutes a part of the drain wiring DL to which the video signal voltage is supplied. A pixel electrode PX using a transparent conductive film such as ITO connected to the source electrode SD2 through a through hole CN penetrating the protective film PSV is disposed on the protective film PSV.
[0039]
In this embodiment, a color filter layer FIL is formed on the pixel electrode PX. Here, in plan view, the pixel electrode PX has a rectangular shape inside one pixel area, that is, inside one pixel area defined by adjacent drain wiring DL and adjacent gate wiring. The color filter FIL uses an organic material, and its planar pattern is a vertical stripe pattern. Of course, the shape is not limited to a stripe shape, and may be a rectangular shape or a square shape particularly when the pixel arrangement is a so-called delta arrangement. As shown in FIG. 1, for example, the color pattern of the green color filter layer FIL (G) and the red color filter layer FIL (R) is divided on the drain wiring DL.
[0040]
Further, a light shielding film BM, a common electrode line CL, and a common electrode CT are disposed on the color filter layer FIL. When the planar pattern of FIG. 2 is seen, the light shielding film BM is formed on the drain wiring DL and the gate wiring GL, and has a structure in which incident light from the surface is not directly applied to the semiconductor layer AS. On the other hand, the common electrode line CL similarly has a mesh pattern disposed on the drain line DL and the gate line GL. The width of the light-shielding film BM is wider, and it has a pattern that overlaps with the lower pixel electrode PX via the color filter layer FIL. The common electrode CT is a part of the common electrode wiring CL, and has a comb-shaped portion in the pixel region. In this embodiment, the light shielding film BM is made of a Cr or Mo metal film, and the common electrode wiring CL is made of a transparent conductive film such as ITO. An alignment film ORI is formed on the common electrode and the color filter FIL in the gap, and the surface thereof is subjected to an alignment process.
[0041]
The light shielding layer BM is made of a metal film of Cr or Mo, the common electrode is made of a transparent conductive film, and the laminated structure of the light shielding layer and the common electrode or the common electrode wiring is provided above the drain by being separated by a color filter FIL. There are two advantages of improving the contrast ratio by shielding light near the drain wiring DL and improving the aperture ratio by using a common electrode and a transparent electrode. Since the common electrode line CL on the video signal line also functions as the common electrode CT, the naming method is not necessarily important. In FIG. 1, a transparent common electrode wider than the light shielding layer BM is laminated on the DL. However, since the end of the common electrode on the DL can also be used as a light transmission region, the aperture ratio can be further improved. . Moreover, although the transparent electrode is used as the upper layer of the light-shielding layer, this has the effect of protecting the metallic light-shielding layer therebelow by using a highly stable transparent conductor as the upper layer due to being an oxide. . In this case, a metallic light-shielding layer is formed, and then a metal layer is first formed by coating, exposure, development, and etching, and then a transparent conductor layer is formed, and coating, exposure, development, and etching are performed in the pixel. The common electrode can be composed of only a transparent electrode. Needless to say, conversely, a metallic light-shielding layer may be an upper layer, and a common electrode of the transparent electrode may be a lower layer. In this case, after the metal layer and the transparent conductor layer are collectively formed, the metal layer is photo-exposed, exposed, developed, and etched, and then the transparent conductor layer is photo-exposed, exposed, developed, and etched, thereby forming a common electrode in the pixel. Can be formed of only a transparent electrode to form a light transmission region, and a continuous film formation of the metal layer and the transparent conductor layer is possible, which has an effect of improving the contact and adhesion between the metal layer and the transparent conductor layer. The light shielding layer BM may also be formed on the gate wiring GL to form a matrix. This is because image quality can be improved by reducing the feeding resistance, and a light shielding layer for shielding the TFT is not required on the counter substrate side, so that the aperture ratio can be further improved. In addition, the effect described above is not necessarily limited to the color filter in the distance between the drain wiring DL and the light shielding layer BM, and an organic insulating film or an inorganic insulating film may be used. From the viewpoint of reducing the parasitic capacitance of the drain wiring DL, an organic insulating film having a low dielectric constant is desirable. Further, the pixel electrode PX is configured in a comb shape as a so-called IPS arrangement, and the liquid crystal molecules are driven by a so-called lateral electric field having a component parallel to the substrate between the pixel electrode PX and the common electrode CT. The above effects can be achieved. In the above description, when the light shielding layer is an upper layer, when an organic insulating film is used instead of the color filter, when the pixel electrode PX is comb-like, when the light shielding layer is provided on the gate wiring GL, and The configuration when these are combined is not shown. This is because those skilled in the art can easily understand structural changes from the above description.
[0042]
Further, a laminated structure of the light shielding layer and the common electrode wiring CL may be provided only on the gate wiring GL. The effect of reducing the feeding resistance due to the fact that the light shielding layer is a metal layer can be achieved. In particular, in the normally black mode, the liquid crystal on the transparent electrode does not operate if it has the same potential, that is, displays black and does not cause a significant reduction in contrast. Even if it is composed of only the common electrode wiring CL, it is possible to realize a practically acceptable constant image quality.
[0043]
On the other hand, an alignment film ORI is formed inside the second substrate SUB2 made of glass, and the surface thereof is rubbed. The first glass substrate SUB1 and the second glass substrate SUB2 are disposed to face each other on the alignment film ORI formation surface, and the liquid crystal layer LC is disposed therebetween. A polarizing plate POL is formed on the outer surfaces of the first and second glass substrates SUB1 and SUB2. The first substrate SUB1 and the second substrate SUB2 are not limited to glass but may be a transparent substrate such as plastic.
[0044]
In the TFT liquid crystal display device formed as described above, when an electric field is not applied to the liquid crystal layer LC, the liquid crystal molecules in the liquid crystal layer LC have a homogeneous alignment that is substantially parallel to the first glass substrate SUB1. is doing. However, the initial alignment state is not limited. When a voltage difference is applied between the common electrode CT and common electrode wiring CL formed on the first glass substrate SUB1 and the pixel electrode PX, an electric field is generated, and liquid crystal molecules rotate at a value equal to or higher than the threshold electric field, and the transmittance is controlled. Is done. The lines of electric force applied to the liquid crystal layer pass from the common electrode CT to the pixel electrode PX through the liquid crystal layer LC and the color filter layer FIL. In this structure, since a lot of electric field components in the lateral direction with respect to the substrate are included, a component in which liquid crystal molecules rotate with respect to the substrate becomes dominant, and a liquid crystal display device with a wide viewing angle can be obtained.
Further, the comb-like common electrode CT and the pixel electrode PX in the pixel region overlap with each other with the color filter layer FIL interposed therebetween, and the maximum electric field applied to the liquid crystal layer LC is defined by the thickness of the color filter layer FIL. . The color filter layer is formed of a 1 to 2 μm resin layer. In this method, the maximum electric field between the pixel electrode PX and the common electrode CT is defined by a planar dimension on the first glass substrate SUB1, for example, as compared with an IPS liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 2000-11957. The driving voltage can be reduced. In the above publication, a transparent insulating film is further formed on the pixel color filter, and a pixel electrode and a common electrode are arranged so as to sandwich the transparent insulating film, and the patterning of the transparent insulating film and the patterning formed thereon are performed. In this embodiment, the process can be simplified and the number of interlayer alignment can be reduced, so that the aperture ratio can be improved and a bright liquid crystal display can be provided.
[0045]
Next, an example of a manufacturing method will be described. First, as shown in FIG. 3A, a laminated film of Cr, Mo, or Al and Mo is formed, and this is patterned by photolithography and etching techniques to form on the first glass substrate SUB1. A gate wiring GL is formed.
[0046]
Next, as shown in FIG. 3B, a gate insulating film GI made of SiN is formed on the first glass substrate SUB1 including the gate wiring GL, and the gate wiring GL is made of amorphous silicon through this. A semiconductor film AS and a high concentration semiconductor film d0 are formed. The n-type high concentration semiconductor film d0 to which the semiconductor film AS and phosphorus are added is formed by continuously forming the gate insulating film GI, the semiconductor film AS, and the high concentration semiconductor film d0, and then using the photolithography and etching techniques. It is formed by patterning d0 and the semiconductor film AS.
[0047]
Next, as shown in FIG. 3C, the drain electrode SD1 and the source electrode SD2 are formed so as to partially overlap the pattern with the high concentration semiconductor film d0. Thereafter, using the drain electrode SD1 and the source electrode SD2 as a mask, the high concentration semiconductor layer d0 is removed by dry etching to form a TFT channel region. The drain wiring DL is formed of the same process and material as the drain electrode SD1.
[0048]
Next, as shown in FIG. 4A, a protective film PSV is formed on the gate insulating film GI using SiN so as to cover the drain electrode SD1, the source electrode SD2, the semiconductor film AS, and the drain wiring DL. Subsequently, a contact hole CN of the protective film PSV is opened on the source electrode SD2 by photolithography and etching. Next, as shown in FIG. 4B, a pixel electrode PX using a transparent conductive film made of ITO is formed on the protective film PSV. The pixel electrode PX is substantially rectangular in plan and is connected to the source electrode SD1 through the contact hole CN.
[0049]
Next, as shown in FIG. 5A, a color filter layer FIL is formed on the protective film PSV and the pixel electrode PX. The color filter layer FIL is formed of, for example, a resin film containing a red (R), green (G), or blue (B) dye or pigment. For example, a pigment dispersion resist in which a pigment capable of obtaining desired optical characteristics such as red is dispersed in an acrylic-based photosensitive resin is used. First, a pigment dispersion resist is applied onto the pixel electrode PX and the protective film PSV, and this is formed by exposure and development so that a pattern edge comes on the adjacent drain wiring DL using a photomask. The color filter layer FIL can be formed by repeating these steps three times for the number of colors, for example, three colors of red (R), blue (B), and green (G).
[0050]
Next, as shown in FIG. 5B, a light shielding film BM of Cr or Mo is formed, and finally, the common electrode wiring CL and the common electrode CT are formed of a transparent conductive film using ITO. The common electrode line CL is formed so that the drain line DL is covered with a color filter FIL. The common electrode CT has a comb shape and overlaps with the lower pixel electrode PX via the color filter FIL.
The light shielding film BM is formed of a metal film. In this case, however, there is an advantage that the common potential can be transmitted to lower resistance together with CL. Also, a resin film may be used, and in this case, there is an effect that the capacity between CL and DL can be further reduced. Further, it can be omitted depending on the application, whereby the process is simplified, the yield is improved, and an inexpensive liquid crystal display device can be provided. In particular, when the semiconductor film AS is made of polycrystalline silicon, giant crystal silicon, or continuous grain boundary silicon (CGS) in which crystal grain boundaries of silicon polycrystalline are adjacent to each other, the TFT generated by light irradiation is turned off. Since the leakage current between the drain electrode SD1 and the source electrode SD2 in the state can be reduced, the light shielding film BM can be easily removed.
[0051]
As described above, in this embodiment, the lines of electric force from the common electrode CT and the common electrode wiring CL on the color filter FIL pass through the liquid crystal layer LC in FIG. 1 and pass through the color filter layer FIL to the lower pixel electrode PX. It reaches. The liquid crystal molecules in the liquid crystal layer LC are rotated by the electric field determined by the lines of electric force, and the transmittance is controlled. Furthermore, in the pixel region of this embodiment, as shown in FIGS. 1 and 2, no through hole is formed in the color filter layer FIL. This is a significant difference from the IPS liquid crystal display device disclosed in Japanese Patent Laid-Open No. 2000-111957, in which a color filter is formed on the first glass substrate SUB1. As a result, yield reduction due to contact failure that occurs when contact holes are formed in each pixel of the color filter FIL made of resin, and uneven brightness due to differences in contact resistance between pixels are fundamentally eliminated. I was able to do it. As a result, as a wide viewing angle liquid crystal display device in which the pixel electrode PX, the common electrode CT, and the color filter layer FIL are formed on the first glass substrate SUB1, the liquid crystal has high yield quality and eliminates luminance unevenness for each pixel. A display device was realized.
[0052]
In this embodiment, the TFT is described, but an MIM may be used.
[0053]
In this embodiment, the configuration of the pixel portion has been described. In the peripheral portion, various circuits such as a scanning signal driving circuit, a video signal driving circuit, and a control circuit are provided, and the liquid crystal display device is driven thereby. Needless to say. Of course, some or all of these circuits are composed of active elements using continuous grain boundary silicon CGS in which polycrystalline silicon, giant crystalline silicon, or polycrystalline silicon crystal grain boundaries are adjacent to each other on the first substrate SUB1. May be.
[0054]
Further, the metal material used for the wiring or electrode may be Ta, W or the like other than the materials shown in the above description.
[0055]
Needless to say, in the case of a transmissive or front light type liquid crystal display device, a backlight unit is provided on the back of one polarizing plate.
[0056]
[Example 2]
Differences in structure between the present embodiment and the first embodiment will be described with reference to FIGS. FIG. 6 shows a cross section taken along the line BB ′ of FIG.
[0057]
In the liquid crystal display device of the present embodiment, the gate electrode GL and the common electrode line CL are arranged on the first glass substrate SUB1, and the common electrode CT formed of a transparent conductive film such as ITO is shown in FIG. In addition, the common electrode wiring CL is overlapped and connected. The common electrode CT has a rectangular shape in plan view while not overlapping with the gate wiring GL and the drain wiring DL. A gate insulating film GI is covered so as to cover the electrodes and wirings of the first glass substrate SUB1. A semiconductor layer AS, a drain electrode SD1, and a source electrode SD2 are formed on the gate insulating film GI, and an n-type high-concentration semiconductor layer d0 doped with phosphorus is formed between the electrode and the semiconductor layer AS. . The source electrode SD2 and the drain electrode SD1 are formed of the same metal film as in the first embodiment. The drain electrode SD1 constitutes a part of the drain wiring DL.
[0058]
The pixel electrode PX connected to the source electrode SD2 is formed of a transparent conductive film such as ITO. The pixel electrode PX has a comb-tooth shape in the pixel region, and the comb-tooth is formed via the lower gate insulating film GI. It overlaps with the common electrode CT. PX should just have a linear area | region and the both ends may be mutually connected. The pixel electrode PX is covered with a protective film PSV using SiN. On the protective film PSV, a color filter layer FIL is formed. A light shielding film BM serving as both a light shielding for the TFT portion and a black matrix around the drain wiring DL is formed thereon. An alignment film ORI is formed thereon, and is subjected to alignment treatment in the same manner as the alignment film ORI formed inside the second glass substrate SUB2.
As described above, in this embodiment, the lines of electric force extending from the pixel electrode PX below the protective film PSV are lowered again through the protective film PSV, the color filter layer FIL, and the liquid crystal layer LC, The color filter layer FIL, the protective film PSV, and the gate insulating film GI in the gap between the pixel electrodes PX reach the common electrode CT. Here, the dielectric anisotropy of the liquid crystal used is not particularly specified. However, in this structure, a material having a positive dielectric anisotropy is more desirable because it can lower the driving voltage.
[0059]
As in the first embodiment, the present embodiment is characterized in that no contact hole is formed in each pixel of the color filter FIL formed of this resin, and the yield can be increased as compared with the conventional known example. Furthermore, the present embodiment has a great advantage that point defects can be reduced as compared with the first embodiment. The reason will be described below.
[0060]
It is known that adhesion between an organic material and an inorganic material is more difficult than organic materials or inorganic materials. However, in Example 1, it is necessary to form the common electrode CT which is an inorganic material made of a conductive metal or a transparent conductor on the color filter FIL. For this reason, the common electrode is easily peeled off from the FIL in the manufacturing process, and has a structure in which point defects are likely to occur. Furthermore, since the common electrode CT is processed into a comb-teeth shape or a line shape, its width is narrow and it is more easily peeled off. When the FIL-like component is peeled off, if it is an electrode, the light cannot be controlled in the region, and even if the light itself is controllable, the gap of the liquid crystal layer is changed, leading to uneven brightness. On the other hand, in this embodiment, a light shielding layer is formed on the FIL. This light shielding layer is formed of resin as an example. In this case, since the light shielding layer BM and the color filter FIL are organic materials, the structure is relatively difficult to peel off. Further, when the light shielding layer BM is formed of a metal material, it can be formed wider than the CT of Example 1 because it is a light shielding layer, so that the contact area with the FIL can be increased, so that a structure that is less likely to peel than Example 1 can be realized. In other words, in this embodiment, even when the light shielding layer BM is a resin or a metal, the constituent layers on the FIL can be made harder to peel than in the first embodiment, and the yield can be improved.
[0061]
Example 3
FIG. 8 shows a cross-sectional view. A gate line GL for driving a scan voltage on the first glass substrate SUB1, a drain line DL for supplying a video signal voltage, and a drain electrode SD1, a source electrode SD2, and a gate insulating film GI formed of SiN. A protective film PSV and a pixel electrode PX disposed on the protective film PSV and connected to the source electrode SD2 are formed. The structure up to the pixel electrode PX and the manufacturing process are the same as those in the first embodiment.
[0062]
The difference between the present embodiment and the first embodiment is the structure above the pixel electrode PX in the pixel and the corresponding process. The color filter layer FIL is a TFT semiconductor layer AS, and the color filter layer FIL (G) of the adjacent pixel is superimposed on the color filter layer FIL (R) for a single color. As described above, by overlapping at least two or more color filters FIL, a light shielding film effect from light incident from the second glass substrate SUB2 side is enhanced. Although two layers are stacked in FIG. 6, the light shielding effect is further enhanced by overlapping another color of the blue color filter FIL (B).
[0063]
In this embodiment, the color layer of the color filter layer FIL is a part of a pixel and is overlapped in a two-layer or three-layer plane to form at least a part of a light shielding film of a TFT portion or a black matrix separating pixels. As applied. Thereby, compared with Example 1, the light shielding film BM formed by the separate film formation and patterning can be omitted. The color filter layer FIL is formed of, for example, a resin film containing a red (R), green (G), or blue (B) dye or pigment. For example, a pigment dispersion resist in which a pigment capable of obtaining desired optical characteristics such as red is dispersed in an acrylic-based photosensitive resin is used. First, a pigment dispersion resist is applied on the pixel electrode PX and the protective film PSV, and this is exposed and developed using a photomask. The color filter layer FIL can be formed by repeating these steps three times for the number of colors, for example, three colors of red (R), blue (B), and green (G).
[0064]
In this embodiment, an overcoat layer OC made of a transparent insulating film material is formed on the color filter layer FIL. For example, a thermosetting resin such as an acrylic resin is used for the overcoat layer OC. Further, a photocurable transparent resin may be used. On top of that, CL and CT were formed. The overcoat layer OC has a flattening effect capable of reducing defects generated in the rubbing process of the alignment film ORI due to the level difference between the color filter layers FIL partially overlapped. Thereby, in the TFT liquid crystal display device in which the interval between the adjacent drain lines DL and the adjacent gate lines GL is reduced, and the interval between the drain lines DL is 80 μm or less as an example, it is accompanied by the alignment process, particularly the rubbing process. Defects were reduced compared to Example 1.
[0065]
Further, in this embodiment, it is determined by the electric lines of force from the common electrode CT and the common electrode wiring CL on the color filter FIL through the liquid crystal layer LC to the pixel electrode PX below the color filter layer FIL and the overcoat layer OC. The liquid crystal molecules in the liquid crystal layer LC are rotated by the electric field, and the transmittance is controlled.
[0066]
Example 4
9 and 10 show a liquid crystal display device of a system according to Embodiment 4 of the present invention. FIG. 9 shows a cross section on the line CC ′ of the plan view of one pixel in FIG. A gate line GL for driving a scan voltage on the first glass substrate SUB1, a drain line DL for supplying a video signal voltage, and a drain electrode SD1, a source electrode SD2, and a gate insulating film GI formed of SiN. A protective film PSV and a pixel electrode PX disposed on the protective film PSV and connected to the source electrode SD2 are formed. The structure up to the pixel electrode PX and the manufacturing process are the same as those in the first embodiment.
[0067]
A color filter layer FIL is formed on the protective film PSV. In this embodiment, the planar pattern of the color filter layer FIL is greatly different from those in the first and second embodiments. The color filter layer FIL has a boundary in the vicinity of the adjacent drain wiring DL, but the adjacent color filter layers FIL have regions separated from each other. In the cross-sectional view of FIG. 9, the red color filter layer FIL (R) and the green color filter layer FIL (G) indicate that there are regions that overlap or do not contact each other in the vicinity of the drain wiring DL.
On the other hand, since the gap between the adjacent color filter layers FIL has a large step, an overcoat layer OC made of a transparent insulating film material is formed from the upper part thereof. For example, a thermosetting resin such as an acrylic resin is used for the overcoat layer OC. Further, a photocurable transparent resin may be used. This overcoat layer OC has a flattening effect to reduce the coating failure of the alignment film ORI due to the level difference between the color filter layers FIL and further the alignment failure.
[0068]
Above that, the common electrode CT and the common electrode wiring CL for driving the liquid crystal layer LC are arranged in a comb-tooth shape. The common electrode CT is formed of a transparent conductive film such as ITO. However, as in the first to third embodiments, a metal film such as Cr or Mo may be used for both the common electrode CT and the common electrode wiring CL. In this case, the transmittance is lowered, but the resistance is lower than that of ITO, and also serves as a light shielding film. Therefore, it is not necessary to provide a special light shielding film BM, and a TFT liquid crystal display device having a larger screen can be provided.
[0069]
The greatest feature of this embodiment is that, as described above, the color filter layers of each pixel are separated so as not to overlap each other along the adjacent drain wiring DL, or further along the adjacent gate wiring. 1 pixel and 1 pixel are separated. This is to realize the following performance improvement. For color resists that determine the color of the color filter, high color purity and high transmittance are in a trade-off relationship. The inventors have found that a material having conductivity is promising as a material satisfying such a trade-off. As another promising material, it has been found that a material containing an ionic component is promising.
[0070]
However, when trial manufacture was performed according to the actual product structure, unexpected new phenomena such as deterioration of crosstalk, increase of drive voltage, and poor reliability occurred. As a result of analyzing these in detail, it came to the interpretation that the cause was as follows. That is, when these materials are used for the color filter FIL and the color filter layers FIL between adjacent pixels are overlapped, the potential of the pixel electrode PX leaks to the adjacent pixels in a highly conductive material, As a result, it was found that the deterioration of the crosstalk and the decrease of the effective voltage, that is, the increase of the driving voltage occurred. In addition, when an ionic component is included, it has been found that the exchange of ions occurs between the color filters FIL that are in contact with each other, and a color fading phenomenon occurs in the color filter FIL. It was also found that this fading phenomenon represents a reliability problem that progresses with time. And when it has electroconductivity and an ionic component, it turned out that the replacement | exchange of ion is accelerated by the actual drive of a liquid crystal display device, ie, electricity supply, and discoloration occurs rapidly.
[0071]
Therefore, in order to apply a color filter having conductivity, an ionic component, or a conductive and ionic component, the inventors have shown a sectional view in FIG. 9 and a plan view in FIG. The structure shown is devised. That is, the color filter FIL is separated for each pixel, and the color filters are further separated by the transparent overcoat film OC. Further, the overcoat film OC is provided between the color filter FIL and an electrode or a conductive material formed on the color filter, for example, the common electrode CT.
[0072]
In the former method, when the color filter has conductivity, the color filter can be prevented from being short-circuited between pixels, so that the deterioration of the crosstalk and the increase of the driving voltage can be prevented. Moreover, when a color filter has an ionic component, ion exchange between color filters can be prevented, and fading of the color filter can be prevented.
[0073]
In the latter method, when the color filter has conductivity, a short circuit between the pixel electrode PX and the common electrode CL can be prevented. When the color filter has an ionic component, the ionic component in the color filter can be prevented from dissolving into the liquid crystal layer and contaminating the liquid crystal layer, and ion exchange between the liquid crystal layer and the color filter can be suppressed. Again, fading of the color filter can be prevented.
[0074]
In FIG. 10, the gate lines GL are not separated from each other, and the color filters along the drain lines DL are not overlapped. However, a certain effect can be realized even with this structure. This is because the gate line GL is wider than the drain line DL, and the distance between pixel electrodes adjacent in the video signal line extending direction can be kept larger than the distance between pixel electrodes adjacent in the scanning signal line extending direction. This is because leakage between pixel electrodes can be reduced. A protective film is formed on the TFT as shown in FIG. This also serves to prevent a short circuit between the source and drain due to the color filter FIL.
[0075]
In this embodiment, the case where the common electrode CL is formed on the same substrate as the pixel electrode PX has been mainly described. However, the effect of this embodiment is that the common electrode CL is formed on the substrate facing the pixel electrode PX. The same applies to the case where this is done, and is included in this embodiment.
[0076]
The color filter FIL may be separated between the pixels in both the scanning signal line extending direction and the video signal line extending direction. In this case, the pixel electrodes between adjacent pixels in the video signal line extending direction may also be separated from each other. Since it can be completely separated, the effect of this embodiment can be realized more reliably.
[0077]
When the color filter FIL is conductive, the potential of the pixel electrode PX is transmitted to the surface side of the FIL due to the conductivity of the color filter layer FIL, and the potential of the pixel electrode PX reaches the liquid crystal layer LC side. A new effect that a low TFT liquid crystal display device can be provided was realized. At this time, if the resistivity indicating the electrical conductivity of the color filter is 10 14 Ωcm or less, the effect of voltage reduction can occur. Further, in order to lower the driving voltage, it is desirable that it is 10 10 Ωcm or less. Needless to say, the lower the drive voltage, the stronger the effect of lowering the drive voltage. However, if the resistance is lowered too much, the light transmittance tends to decrease, so the range is from 10 3 Ωcm to 10 10 Ωcm. Most desirable.
[0078]
In the liquid crystal display device having the configuration of this embodiment, the driving electric field applied to the liquid crystal layer passes through the color filter layer. In a conventional method, for example, a method in which a color filter is provided on a substrate different from the TFT, in one example, the pixel electrode is on the TFT substrate, the common electrode is on the color filter of the color filter substrate, and the pixel electrode is between the common electrode. There is a vertical electric field system that generates a driving electric field. In this method, the driving electric field applied to the liquid crystal layer does not pass through the color filter layer. In the so-called lateral electric field method, both the pixel electrode and the common electrode are provided on the TFT substrate, and a driving electric field is formed between the electrodes. Therefore, the driving electric field applied to the liquid crystal layer does not pass through the color filter layer. Further, even in a method in which a color filter is provided on a TFT substrate, a conventionally known method is to provide a pixel electrode on a color filter and a common electrode on a counter substrate, and form a driving electric field on the liquid crystal layer between them. Also, the driving electric field applied to the liquid crystal layer does not pass through the color filter layer. However, in this embodiment, a color filter layer is provided between the pixel electrode and the common electrode, and a driving electric field is formed in the liquid crystal layer through the color filter layer. Therefore, when the color filter layer has ionic impurities as in this embodiment, or has conductivity, or contains some contaminant impurities, for example, metal ions or organic solvents, the liquid crystal layer. Since the reaction of the color filter is accelerated by the driving electric field passing through the color filter, a new problem has been found that the contamination of the liquid crystal layer is accelerated. Accordingly, from the viewpoint of ensuring the reliability of the liquid crystal display device and preventing the contamination of the liquid crystal layer, a color filter layer is provided between the pixel electrode and the common electrode, and the liquid crystal layer is driven through the color filter layer. In the method of forming an electric field, it is highly desirable to form a protective film for preventing contamination between the color filter and the liquid crystal layer. Further, when the protective film is an organic film, it is more desirable because a planarization effect can be realized together.
[0079]
As described above in detail, with the configuration of this embodiment, a color TFT is disposed on the TFT substrate, and a bright TFT liquid crystal display device with high color purity can be realized.
[0080]
The present invention is not limited to the embodiments of Examples 1 to 4 including technical ideas and effects, and the configurations and effects of the technical ideas disclosed in the specification including the claims are within the scope of the present invention. Includes everything.
[0081]
【The invention's effect】
A typical example of the effect of the present invention is as follows. That is, a TFT liquid crystal display device in which a pixel electrode and a common electrode for driving a liquid crystal layer are arranged on a first glass substrate without forming a through hole in a color filter for each pixel, and a color filter layer is also built in is provided. it can.
[0082]
Further, when a liquid crystal display device having a wide viewing angle is formed by rotating liquid crystal molecules horizontally on the substrate using a simple manufacturing method, a liquid crystal display device in which not only TFTs but also CFs are formed on the first substrate, and The manufacturing method can be provided.
[0083]
Furthermore, a liquid crystal display device having a high aperture ratio or high transmittance and a method for manufacturing the same can be provided.
[0084]
In addition, a bright TFT display device with a wide viewing angle can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a pixel of an embodiment of a liquid crystal display device of the present invention.
FIG. 2 is a plan view of a pixel of an embodiment of the liquid crystal display device of the present invention.
FIG. 3 is an explanatory diagram of a manufacturing method of an embodiment of the liquid crystal display device of the present invention.
FIG. 4 is an explanatory diagram of a manufacturing method of an embodiment of the liquid crystal display device of the present invention.
FIG. 5 is an explanatory diagram of a manufacturing method of an embodiment of the liquid crystal display device of the present invention.
FIG. 6 is a cross-sectional view of a pixel of an embodiment of the liquid crystal display device of the present invention.
FIG. 7 is a plan view of a pixel of an embodiment of the liquid crystal display device of the present invention.
FIG. 8 is a cross-sectional view of a pixel of an embodiment of the liquid crystal display device of the present invention.
FIG. 9 is a cross-sectional view of a pixel of an embodiment of the liquid crystal display device of the present invention.
FIG. 10 is a plan view of a pixel of an embodiment of the liquid crystal display device of the present invention.
[Explanation of symbols]
AS ... semiconductor film, SUB1 ... first glass substrate, SUB2 ... second glass substrate, SD1 ... drain electrode, SD2 ... source electrode, GL ... gate wiring, DL ... drain wiring, CL ... common electrode wiring, CT ... common Electrode, TFT ... Thin film transistor, GI ... Gate insulating film, PSV ... Protective film, PX ... Pixel electrode, FIL ... Color filter layer, LC ... Liquid crystal layer, ORI ... Alignment film, OC ... Overcoat film, BM ... Light-shielding film, POL …Polarizer.

Claims (27)

Having a liquid crystal layer sandwiched between the first and second transparent substrates and the first and second substrates;
The first substrate has a plurality of video signal lines, a plurality of scanning signal lines, and a plurality of pixel areas formed as an area surrounded by the video signal lines and the scanning signal lines, and each pixel area is at least In a liquid crystal display device having one active element and a pixel electrode, and having a color filter layer between the pixel electrode and the liquid crystal layer,
With boundary of the color filter layer of pixels adjacent to the scanning signal lines extending direction is positioned on the video signal lines, the liquid crystal layer and the color filter layer superposed on the boundary portion and the video signal line A light shielding layer is formed between
A liquid crystal display device, wherein a common signal line serving as a common electrode and a common signal line is provided between the color filter layer and the liquid crystal layer of the substrate on which the color filter layer is formed.   The liquid crystal display device according to claim 1, wherein an organic flattening film is formed between the light shielding layer and the color filter layer. The common electrode and the common signal line which also serves as a common electrode, a liquid crystal display device according to claim 2, characterized in that provided between the liquid crystal layer and the organic planarization layer.   The liquid crystal display device according to claim 1, wherein the common signal line also serves as the light shielding layer.   The liquid crystal display device according to claim 1, wherein the common signal line covers the light shielding layer on the video signal line. Having a liquid crystal layer sandwiched between the first and second transparent substrates and the first and second substrates;
The first substrate has a plurality of video signal lines, a plurality of scanning signal lines, and a plurality of pixel regions formed as a region surrounded by the video signal lines and the scanning signal lines, and each pixel region is at least In a liquid crystal display device having one active element, a pixel electrode, and a common electrode, and having a color filter layer between the pixel electrode and the liquid crystal layer,
The common electrode is formed above the color filter layer, the pixel electrode is formed below the color filter layer, and the color filter layer overlaps at least the entire surface of the pixel electrode in the pixel region. A liquid crystal display device.   The liquid crystal display device according to claim 6, wherein an organic planarization film is formed between the color filter layer and the common electrode.   The liquid crystal display device according to claim 6, wherein the pixel electrode has a planar shape and the common electrode has a linear region.   The liquid crystal display device according to claim 6, wherein a part of the common electrode is disposed so as to overlap the video signal line and also serves as a common signal line.   9. The liquid crystal display device according to claim 6, wherein a part of the common electrode is disposed so as to overlap with the scanning signal line, and also serves as a common signal line.   9. The liquid crystal display device according to claim 6, wherein a part of the common electrode is disposed so as to overlap the scanning signal line and the video signal line, and also serves as a common signal line.   The liquid crystal display device according to claim 9, wherein the common signal line also serving as the common electrode overlaps at least an end surface of the pixel electrode.   13. The liquid crystal display device according to claim 9, wherein the common signal line also serving as the common electrode is a transparent conductor, and has a light shielding layer on at least the active element.   The liquid crystal display device according to claim 9, wherein the common signal line also serving as the common electrode is a metal.   The liquid crystal display device according to claim 6, wherein the pixel electrode is a transparent electrode. A first and second transparent substrate; and a liquid crystal layer sandwiched between the first and second substrates, wherein the first substrate includes a plurality of video signal lines, a plurality of scanning signal lines, and the A plurality of pixel regions formed as regions surrounded by the video signal lines and the scanning signal lines, and each pixel region includes at least one active element, a pixel electrode, and a common electrode; In a liquid crystal display device having a color filter layer between liquid crystal layers,
The liquid crystal display device, wherein the common electrode and the pixel electrode are formed below the color filter layer, and the color filter layer overlaps at least the entire surface of the pixel electrode and the common electrode in the pixel region. .   The liquid crystal display device according to claim 16, wherein the common electrode is a transparent conductor, and is formed below the pixel electrode through at least a gate insulating film.   The liquid crystal display device according to claim 16, wherein the common electrode has a planar shape, and the pixel electrode has a linear region.   The common signal line arranged on the same layer and spaced apart from the scanning signal line, and the common signal line has an overlapping region with the common electrode. Liquid crystal display device.   A boundary of the color filter layer of pixels adjacent in the extending direction of the scanning signal line is positioned on the video signal line, and the color filter layer and the liquid crystal are superimposed on the boundary and the video signal line. The liquid crystal display device according to claim 16, wherein a light shielding layer is formed between the layers. A first and second transparent substrate; and a liquid crystal layer sandwiched between the first and second substrates, wherein the first substrate includes a plurality of video signal lines, a plurality of scanning signal lines, and the a plurality of pixel regions formed as a region surrounded by the scanning signal lines and image signal lines, each pixel region has at least one active element and the picture element electrode and the common electrode, wherein the pixel In a liquid crystal display device having a color filter layer between liquid crystal layers,
The color filter layer is formed between the pixel electrode and the common electrode, and a driving electric field for the liquid crystal layer passes through both the liquid crystal layer and the color filter layer between the pixel electrode and the common electrode. A liquid crystal display device formed by   The common electrode is formed between the color filter layer and the liquid crystal layer, the common electrode has a linear region and a region formed on the video signal line, and the pixel electrode is the color electrode. The liquid crystal display device according to claim 21, wherein the liquid crystal display device is formed under a filter layer, and the pixel electrode and the color filter layer are in contact with each other.   The boundary of the color filter layer between pixels adjacent in the scanning signal line extending direction is positioned on the video signal line, and the adjacent color filter layers overlap at the boundary, and the color filter layer 23. The liquid crystal display device according to claim 21, wherein an organic flattening film is formed thereon.   The boundary of the color filter layer between adjacent pixels in the scanning signal line extending direction is positioned on the video signal line, and the adjacent color filter layers at the boundary are separated by an insulating organic transparent film. The liquid crystal display device according to claim 21, wherein the liquid crystal display device is a liquid crystal display device.   The color filter layer is integrally formed between adjacent pixels in the video signal line extending direction, and an inorganic insulating film is formed between the active element and the color filter layer. Item 25. The liquid crystal display device according to any one of items 21, 22 and 24.   The boundary of the color filter layer between adjacent pixels in the video signal line extending direction is positioned on the scanning signal line, and the adjacent color filter layers at the boundary are separated by an insulating organic transparent film. 25. The liquid crystal display device according to claim 21, 22 or 24.   27. The liquid crystal display device according to claim 21, wherein an organic planarizing film is formed on the color filter layer.

Images