Patent Abstract:
A liquid crystal display device including first and second substrates, a liquid crystal layer, a plurality of gate bus lines and a plurality of drain bus lines. A plurality of pixel regions are defined by the gate bus lines and the drain bus lines. Pixel electrodes are divided into at least four regions such that at least four domains of different liquid crystal orientation directions are defined within the pixel regions. The first and second regions each include a micro-cutout pattern including a plurality of cutouts extending in a slanted direction with respect to an edge of the first or second region, respectively, and the cutouts of the first region and the cutouts of the second region are generally parallel to each other both within each of the regions as well as across the first and second regions.

Full Description:
This application is a Continuation of U.S. patent application Ser. No. 10/720,706, filed Nov. 24, 2003, which is a Divisional of U.S. patent application Ser. No. 10/166,119, filed Jun. 10, 2002, now U.S. Pat. No. 7,145,619. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid crystal display substrate that forms a part of a liquid crystal display used in a display section of an information apparatus or the like, a liquid crystal display having the same and a method of manufacturing the same. 
     2. Description of the Related Art 
     In general, a liquid crystal display comprises two substrates having a transparent electrode and a liquid crystal sealed between the two substrates. The liquid crystal is driven by applying a voltage between the two transparent electrodes to control the transmittance of light through the liquid crystal, which allows a desired image to be displayed. An active matrix liquid crystal display is comprised of a TFT substrate having thin film transistors (TFTs) for switching respective pixels formed thereon and a common electrode substrate having a common electrode formed thereon. A recent increase in the need for liquid crystal displays has resulted in diverse requirements for liquid crystal displays. In particular, there are strong demands for improvements of viewing angle characteristics and display quality, and VA (vertically aligned) mode liquid crystal displays are regarded as promising means for satisfying such demands. 
     A VA mode liquid crystal display is comprised of two substrates which have been subjected to a vertically aligning process on surfaces thereof facing each other and a liquid crystal having negative dielectric anisotropy sealed between the two substrates. The liquid crystal molecules of the liquid crystal are characterized by homeotropic alignment and are aligned substantially perpendicularly to the substrate surfaces when no voltage is applied between the electrodes. They are aligned substantially in parallel with the substrate surfaces when a predetermined voltage is applied between the electrodes and are aligned at an angle to the substrate surfaces when a voltage lower than said voltage is applied. 
     MVA (multi-domain vertical alignment) type liquid crystal displays are recently attracting attention from the viewpoint of improvement of viewing angle characteristics of liquid crystal displays. In the case of an MVA type display, a pixel is divided into a plurality of domains using alignment regulating structures such as linear protrusions and slits provided on two substrates to achieve separate alignment in which liquid crystal molecules are tilted in a different direction in each domain. 
       FIG. 35  shows a configuration of an MVA type liquid crystal display and shows an arrangement of linear protrusion formed as alignment regulating structures on two substrates.  FIG. 35  shows three pixels in red (R), green (G) and blue (B). As shown in  FIG. 35 , linear protrusions  104  are formed on a TFT substrate  108  and linear protrusions  106  are formed on a common electrode substrate  110 . The linear protrusions  104  and  106  are formed at an angle to the pixels. Each of the R, G and B pixel regions is defined by a black matrix (BM)  102  formed on the common electrode substrate  110 . The BM  102  serves as a light shield for a storage capacity bus line extending across each pixel substantially in the middle thereof and a storage capacity electrode located above the same (both of which are not shown). 
       FIG. 36  is a sectional view of the liquid crystal display taken along the line X-X in  FIG. 35 . As shown in  FIG. 36 , the TFT substrate  108  has a pixel electrode  114  formed for each pixel on a glass substrate  112 . The figure omits an insulation film, drain bus lines, a protective film, and so on formed on the glass substrate  112 . The linear protrusions  104  are formed on the pixel electrodes  114 . A vertical alignment film  116  is formed to cover the pixel electrodes  114  and linear protrusions  104  entirely. The common electrode substrate  110  has the BM  102  formed on the glass substrate  112 . Resin color filter (CF) layers R, G and B ( FIG. 36  shows the filters G and B only) are formed in each of the pixel regions defined by the BM  102  on the glass substrate  112 . A common electrode  118  is formed on the region CF layers R, G and B, and the linear protrusions  106  are formed on the common electrode  118 . Further, a vertical alignment film  116  is formed to cover the common electrode  118  and linear protrusions  106  entirely. Spherical spacers  122  made of plastic or glass for maintaining a gap (cell gap) between the substrates  108  and  110  and a liquid crystal LC is sealed between the TFT substrate  108  and common electrode substrate  110 . 
       FIG. 37  is a sectional view of the liquid crystal display taken along the line Y-Y in  FIG. 35 , and it shows a state of the liquid crystal LC when no voltage is applied. As shown in  FIG. 37 , liquid crystal molecules (represented by columns in the figure) are aligned substantially perpendicularly to the vertical alignment films  116  on the two substrates  108  and  110 . Therefore, liquid crystal molecules in the regions where the linear protrusions  104  and  106  are formed are aligned substantially perpendicularly to the surface of the linear protrusions  104  and  106  and are aligned at a slight angle to the normal of the two substrates  108  and  110 . Since polarizers (not shown) are provided in a crossed Nicols configuration outside the two substrates  108  and  110 , black display is achieved when no voltage is applied. 
       FIG. 38  is a sectional view of the liquid crystal display taken along the line Y-Y in  FIG. 35  similarly to  FIG. 37 , and it shows a state of the liquid crystal LC when a voltage is applied. The broken lines in the figure represent lines of electric force between the pixel electrodes  114  and common electrode  118 . As shown in  FIG. 38 , when a voltage is applied between the pixel electrodes  114  and common electrode  118 , the electric field is distorted in the vicinity of the linear protrusions  104  and  106  which are made of a dielectric material. As a result, the tilting angles of liquid crystal molecules having negative dielectric anisotropy are regulated, and the tilting angles can be controlled depending on the field intensity to display gray shades. 
     At this time, if the linear protrusions  104  and  106  are provided in linear configurations as shown in  FIG. 35 , liquid crystal molecules in the vicinity of the linear protrusions  104  and  106  are tilted in two directions which are orthogonal to the extending directions of the linear protrusions  104  and  106 , the tilting directions being symmetrically defined about the linear protrusions  104  and  106 . Since the liquid crystal molecules in the vicinity of the linear protrusions  104  and  106  are at a slight angle to a direction perpendicular to the two substrates  108  and  110  even when no voltage is applied, they are quickly tilted in response to the field intensity. The tilting directions of liquid crystal molecules in the neighborhood are sequentially determined in accordance with the behavior of the above-mentioned liquid crystal molecules, and the tilting angles depend on the field intensity. As a result, alignment separation is achieved at the linear protrusions  104  and  106 . 
       FIG. 39  is a sectional view taken along a line Y-Y of a liquid crystal display as shown in  FIG. 35  in which slits  120  are formed in place of the linear protrusions  104 , the figure showing a state of the display when no voltage is applied. As shown in  FIG. 39 , the slits  120  which are alignment regulating structures are formed by removing the pixel electrodes  114 . Liquid crystal molecules are aligned substantially perpendicularly to the vertical alignment films  116  on the two substrates  108  and  110  similarly to the liquid crystal molecules shown in  FIG. 37 . 
       FIG. 40  is a sectional view of the liquid crystal display taken along the line Y-Y similarly to  FIG. 39 , and it shows a state of a liquid crystal LC when a voltage is applied. As shown in  FIG. 40 , lines of electric force substantially similar to those in the regions where the linear protrusions  104  are formed as shown in  FIG. 38  are formed in the regions where the slits  120  are formed. As a result, alignment separation is achieved about the linear protrusions  106  and slits  120 .  FIGS. 37 and 40  omit the spherical spacers  122  for maintaining a cell gap. 
       FIG. 41  is a sectional view of the liquid crystal display taken along the line Z-Z in  FIG. 35  showing the neighborhood of a drain bus line  126 . As shown in  FIG. 41 , the TFT substrate  108  has an insulation film  124  covering an entire surface of the glass substrate  112 . The drain bus line  126  is formed on the insulation film  124 . A protective film  128  is formed on the entire surface of the drain bus line  126 . A pixel electrode  114  for each pixel is formed on the protective film  128 . A black matrix BM  102  is formed on a common electrode substrate  110  provided in a face-to-face relationship with the TFT substrate  108  such that it serves as a light shield for regions on the TFT substrate  108  where no pixel electrode  114  is formed (edges of pixel regions). 
     The conventional MVA type liquid crystal display has the problem of darkness of display because of low transmittance of the panel. The low panel transmittance is attributable to various factors including a reduction in the numerical aperture caused by misalignment between the TFT substrate  108  and common electrode substrate  110 , a reduction in the numerical aperture attributable to the alignment regulating structures (the linear protrusions  104  and  106  or slits  120 ), and irregularities in the alignment of the liquid crystal in the vicinity of the spherical spacers  122 . 
     Because of significantly improved viewing angle characteristics, MVA type liquid crystal displays are preferably used as monitors for personal computers and the like for which high luminance has relatively low importance. However, in order to use them as display sections of DVD (digital versatile disk) players or televisions for which high luminance is an important requirement, it is necessary to provide a brighter back-light or to use a special sheet for aligning light-emitting directions to improve luminance in a particular direction. This has resulted in the problem of an increase in the manufacturing cost. 
     Further, the formation of linear protrusions, an insulation layer, and so on as alignment regulating structures increases manufacturing steps when compared to manufacturing steps for normal substrates, which also results in an increase in the manufacturing cost. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a substrate for a liquid crystal display with which a display having high luminance and preferable display characteristics can be obtained, a liquid crystal display having the same, and a method for manufacturing the same. 
     The above-described object is achieved by a liquid crystal display substrate, characterized in that it comprises a substrate which sandwiches a liquid crystal having negative dielectric anisotropy in combination with an opposite substrate provided in a face-to-face relationship, a plurality of gate bus lines formed on the substrate, a plurality of drain bus lines formed on the substrate such that they intersect the gate bus lines, pixel regions defined by the gate bus lines and the drain bus lines, a thin film transistor formed in each of the pixel regions, a resin color filter layer formed in each of the pixel regions, a pixel electrode formed in each of the pixel regions, and an alignment regulating structure formed on the substrate for regulating the alignment of the liquid crystal. 
     The above-described object is achieved by a liquid crystal display, characterized in that it comprises: a thin film transistor substrate including a first substrate, a plurality of bus lines formed on the first substrate such that they intersect each other, pixel regions defined by the bus lines, a thin film transistor formed in each of the pixel regions, a resin color filter layer formed in each of the pixel regions, and a pixel electrode formed in each of the pixel regions; a common electrode substrate including a second substrate different from the first substrate in the thickness or material and a common electrode formed on the second substrate, the common electrode substrate being provided in a face-to-face relationship with the first substrate; and a liquid crystal sealed between the thin film transistor substrate and the common electrode substrate. 
     Further, the above-described object is achieved by a liquid crystal display substrate, characterized in that it comprises a substrate which sandwiches a liquid crystal in combination with an opposite substrate provided in a face-to-face relationship therewith, a plurality of gate bus lines formed on the substrate, a plurality of drain bus lines formed on the substrate such that they intersect the gate bus lines, pixel regions defined by the gate bus lines and the drain bus lines, a thin film transistor formed in each of the pixel regions, a resin color filter layer formed in each of the pixel regions, a pixel electrode formed in each of the pixel regions, and a resin layer formed to cover source and drain electrodes of the thin film transistor and the drain bus lines. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a configuration of a liquid crystal display in a first mode for carrying out the invention; 
         FIG. 2  is a sectional view showing a first basic configuration of a substrate for a liquid crystal display in the first mode for carrying out the invention, a liquid crystal display having the same, and a method of manufacturing the same; 
         FIG. 3  is a sectional view showing a modification of the first basic configuration of a substrate for a liquid crystal display in the first mode for carrying out the invention, a liquid crystal display having the same, and a method of manufacturing the same; 
         FIG. 4  is a sectional view showing a second basic configuration of a substrate for a liquid crystal display in the first mode for carrying out the invention, a liquid crystal display having the same, and a method of manufacturing the same; 
         FIG. 5  shows a third basic configuration of a substrate for a liquid crystal display in the first mode for carrying out the invention; 
         FIGS. 6A and 6B  show the third basic configuration of a substrate for a liquid crystal display in the first mode for carrying out the invention; 
         FIG. 7  shows a configuration of a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIG. 8  is a sectional view showing a configuration of a substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIG. 9  shows a configuration of a substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIGS. 10A and 10B  are sectional views showing the configuration of the substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIGS. 11A and 11B  are sectional views taken at a manufacturing step showing a method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIGS. 12A and 12B  are sectional views taken at a manufacturing step showing the method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIGS. 13A and 13B  are sectional views taken at a manufacturing step showing the method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIGS. 14A and 14B  are sectional views taken at a manufacturing step showing the method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIGS. 15A and 15B  are sectional views taken at a manufacturing step showing the method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIGS. 16A and 16B  are sectional views taken at a manufacturing step showing the method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-1 in the first mode for carrying out the invention; 
         FIG. 17  is a sectional view showing a configuration of a liquid crystal display according to Embodiment 1-2 in the first mode for carrying out the invention; 
         FIG. 18  is a sectional view showing the configuration of the liquid crystal display according to Embodiment 1-2 in the first mode for carrying out the invention; 
         FIG. 19  shows a configuration of a substrate for a liquid crystal display according to Embodiment 1-3 in the first mode for carrying out the invention; 
         FIG. 20  is a sectional view showing the configuration of the substrate for a liquid crystal display according to Embodiment 1-3 in the first mode for carrying out the invention; 
         FIG. 21  is a sectional view taken at a manufacturing step showing a method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-3 in the first mode for carrying out the invention; 
         FIG. 22  is a sectional view taken at a manufacturing step showing the method of manufacturing the substrate for a liquid crystal display according to Embodiment 1-3 in the first mode for carrying out the invention; 
         FIG. 23  shows a configuration of a substrate for a liquid crystal display according to Embodiment 2-1 in a second mode for carrying out the invention; 
         FIG. 24  is a sectional view taken at a manufacturing step showing a configuration of a liquid crystal display according to Embodiment 2-2 in the second mode for carrying out the invention; 
         FIG. 25  shows a configuration of a liquid crystal display according to Embodiment 3-1 in a third mode for carrying out the invention; 
         FIGS. 26A and 26B  are sectional views showing the configuration of the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIG. 27  shows a method of manufacturing the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIG. 28  shows the method of manufacturing the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIG. 29  shows the method of manufacturing the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIG. 30  shows the method of manufacturing the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIGS. 31A and 31B  are sectional views taken at a manufacturing step showing the method of manufacturing the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIGS. 32A and 32B  are sectional views taken at a manufacturing step showing the method of manufacturing the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIGS. 33A and 33B  are sectional views taken at a manufacturing step showing the method of manufacturing the liquid crystal display according to Embodiment 3-1 in the third mode for carrying out the invention; 
         FIGS. 34A and 34B  are sectional views showing a configuration of a liquid crystal display according to Embodiment 3-2 in the third mode for carrying out the invention; 
         FIG. 35  shows a configuration of a conventional liquid crystal display; 
         FIG. 36  is a sectional view showing the configuration of the conventional liquid crystal display; 
         FIG. 37  is a sectional view showing the configuration of the conventional liquid crystal display; 
         FIG. 38  is a sectional view showing the configuration of the conventional liquid crystal display; 
         FIG. 39  is a sectional view showing the configuration of the conventional liquid crystal display; 
         FIG. 40  is a sectional view showing the configuration of the conventional liquid crystal display; 
         FIG. 41  is a sectional view showing the configuration of the conventional liquid crystal display; and 
         FIG. 42  is a sectional view showing a modification of the substrate for a liquid crystal display according to Embodiment 1-2 in the first mode for carrying out the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Mode for Carrying Out the Invention 
     A description will be made with reference to  FIGS. 1 through 22  and  FIG. 42  on a substrate for a liquid crystal display in a first mode for carrying out the invention, a liquid crystal display having the same, and a method of manufacturing the same. A first basic configuration in the present mode for carrying out the invention will be described with reference to  FIGS. 1 and 2 .  FIG. 1  shows three pixels in R, G and B on a TFT substrate  8 . As shown in  FIG. 1 , the pixels are defined by gate bus lines  25  extending in the horizontal direction in the figure and drain bus lines  26  extending in the vertical direction in the figure. TFTs (no shown) are formed in the vicinity of intersections between the bus lines  25  and  26 . Above the TFTs, in order to prevent light from impinging upon the TFTs, resin overlap sections  32  are formed in which at least two out of resin CF layers R, G and B are overlapped with each other. In the liquid crystal display in the present mode for carrying out the invention, no black matrix is formed on a common electrode substrate which is provided in a face-to-face relationship with the TFT substrate  8 , and the bus lines  25  and  26  and the resin overlap sections  32  formed on the TFT substrate  8  provides the function of a black matrix. Light can be blocked by forming any one of the resin CF layers R, G and B on the TFTs instead of the resin overlap sections  32  shown in  FIG. 1 . 
       FIG. 2  is an illustration showing a first basic configuration of a substrate for a liquid crystal display in the present mode for carrying out the invention and a liquid crystal display having the same is a sectional view of the liquid crystal display taken along the line A-A in  FIG. 1 . As shown in  FIG. 2 , the TFT substrate  8  has an insulation film  24  formed on a substantially entire surface of a glass substrate  12 . The drain bus lines  26  are formed on the insulation film  24 . The resin CF layers R, G and B ( FIG. 2  shows the layers G and B only) are formed on the drain bus lines  26  (a CF-on-TFT structure). A pixel electrode  14  for each pixel is formed on the resin CF layers R, G and B. A common electrode substrate  10  provided in a face-to-face relationship with the TFT substrate  8  is comprised of a glass substrate  12  and a common electrode  18  formed on an entire surface thereof. No black matrix is formed on the common electrode substrate  10 . A vertical alignment film (not shown) is formed to cover the pixel electrode  14  and common electrode  18  entirely. A liquid crystal layer LC is sealed between the TFT substrate  8  and common electrode substrate  10 . 
     In the conventional liquid crystal display shown in  FIG. 41 , a capacity is formed between the pixel electrode  114  and drain bus line  126  with the protective film  128  sandwiched as a dielectric material if the pixel electrode  114  is formed such that it extends above the drain bus line  126 . It is therefore necessary to provide a predetermined gap extending in parallel with the substrate surface between the pixel electrode  114  and drain bus line  126 . 
     On the contrary, in the liquid crystal display in the present mode for carrying out the invention shown in  FIG. 2 , the resin CF layers R, G and B are formed between the pixel electrodes  114  and drain bus lines  126 . Since the resin CF layers R, G and B are applied and formed using a spin coat process or the like, they can be easily formed with a great thickness compared to the protective film  128  that is formed using a CVD (chemical vapor deposition) process. It is therefore possible to reduce any electrostatic capacity generated between the drain bus lines  26  and pixel electrodes  14 . Since this makes it possible to form the pixel electrodes  14  in an overlapping relationship with the drain bus lines  26  in the direction perpendicular to the substrate surface, there is no need for forming a black matrix on the common electrode substrate  10 , which improves the numerical aperture. Further, since the drain bus lines  26  serve as a black matrix to eliminate any need for providing a black matrix on the common electrode substrate  10 , the number of manufacturing steps is reduced. This also eliminates any reduction in the numerical aperture attributable to misalignment between the TFT substrate  8  and common electrode substrate  10 . 
     The CF-on-TFT structure shown in  FIG. 2  is suitable for a TN normally white mode liquid crystal display in which leakage of light can occur when black is displayed unless pixel electrodes  14  are formed such that edges of the same overlap drain bus lines  26 . However, in order to suppress a capacity formed in a region where a pixel electrode  14  and a drain bus line  26  overlap each other, the resin CF layers R, G and B must be formed with a considerably great thickness. This results in a problem in that the CF-on-TFT structure necessitates a manufacturing process that is more complicated than forming the resin CF layers R, G and B on the opposite substrate. Further, in order to block light with the drain bus lines  26  reliably (bus line light-blocking), the resin CF layers R, G and B must be formed such that their edges are accurately aligned with the drain bus lines  26 . Therefore, in the case of drain bus lines with a very small line width, a proximity exposure apparatus which is normally used for forming the resin CF layers R, G and B may fail to achieve sufficient alignment. On the contrary, the use of a stepper or mirror-projection type aligner having excellent aligning accuracy can result in an increase in the manufacturing cost of the CF-on-TFT structure. 
       FIG. 3  shows a modification of the first basic configuration shown in  FIG. 2 . As shown in  FIG. 3 , the pixel electrodes  14  are formed such that predetermined gaps in the direction of the substrate surface are kept between edges of the pixel electrodes  14  and drain bus line  26  in order to prevent the pixel electrodes  14  from overlapping the drain bus line  26  when viewed in the direction perpendicular to the substrate surface. An edge of the resin CF layer G is formed on the drain bus line  26 , however, an edge of the resin CF layer B is misaligned with the top of the drain bus line  26  because of a shift during patterning. However, in the case of a MVA type normally black mode liquid crystal display which displays black when no voltage is applied, even if a pixel electrode  14  is formed with a predetermined gap from a drain bus line  26  such that they do not overlap each other, the problem of leakage light will not occur because such a gap region appears in black when no voltage is applied. Further, since no capacity is generated because no overlap region is formed between the pixel electrode  14  and drain bus line  26 , resin CF layers R, G and B can be as thin as desired. Even when the resin CF layers R, G and B are formed such that their edges are misaligned with the top of the drain bus line  26  as shown in  FIG. 3 , no light leaks as long as the edges of the resin CF layers R, G and B are closer to the drain bus line  26  than the edges of the pixel electrodes  14 . Since this makes it possible to provide a great margin for alignment during the patterning of the resin CF layers R, G and B, the CF-on-TFT structure can be obtained at a low cost using a normal proximity exposure apparatus. 
       FIG. 4  shows a second basic configuration of the substrate for a liquid crystal display in the present mode for carrying out the invention and the liquid crystal display having the same,  FIG. 4  showing a sectional view of the liquid crystal display taken along the line B-B in  FIG. 1 . As shown in  FIG. 4 , the liquid crystal display has linear protrusions  28  as alignment regulating structures formed on the pixel electrodes  14 . The resin CF layers R, B and G are laminated in the same order in the vicinity of the intersection between the gate bus line  25  and drain bus line  26  to form a resin overlap section  32  to serve as a black matrix. A protrusion  29  which does not function as an alignment regulating structure is formed on the resin overlap section  32 . The protrusion  29  is formed simultaneously with the linear protrusions  28  from the same material as that of the latter. The resin overlap section  32  between the resin layers forming a part of the TFT substrate  8  and the protrusion  29  are laminated to form a columnar spacer  30  which maintains a call gap between the TFT substrate and the common electrode substrate  10  provided in a face-to-face relationship. 
     In the second configuration in the present mode for carrying out the invention, the columnar spacer is formed by laminating the resin CF layers and so on forming a part of the TFT substrate  8 . Since this reduces the number of manufacturing steps, the manufacturing cost can be reduced. Further, since this makes it possible to reduce leakage of light and irregularities of alignment that can occur in the vicinity of dispersed spacers having a spherical configuration or the like, preferable display characteristics can be achieved. 
       FIG. 5  shows a third configuration of the substrate for a liquid crystal display in the present mode for carrying out the invention. A frame pattern  34  for shielding edges of a display area  38  from light is formed in a frame region  40  of the common electrode substrate  10 . For example, across-shaped alignment mark used for combining the same substrate with the TFT substrate  8  (which is not shown in  FIGS. 5 and 6B ) in a face-to-face relationship is formed outside the frame region  40 . 
       FIG. 6A  is an enlarged view of the region α of the common electrode substrate  10  shown in  FIG. 5 .  FIG. 6B  shows a section of the common electrode substrate  10  taken along the line C-C in  FIG. 6A . As shown in  FIGS. 6A and 6B , a common electrode  18  is formed in the display area  38  on the glass substrate  12  and in the frame region  40  at the edges of the display area  38 . Linear protrusions  28  are formed on the common electrode  18  in the display area  38  at an angle to an edge of the display area  38  using a black resist (black resin) or the like. A frame pattern  34  for shielding the edges of the display area  38  from light is formed on the common electrode  18  in the frame region  40  simultaneously with the linear protrusions  28  from the same material. An alignment mark  36  is formed simultaneously with the linear protrusions  28  from the same material on the left side of the frame region  40  in the figures. 
     In the third basic configuration in the present mode for carrying out the invention, since the frame pattern  34  and alignment mark  36  are formed simultaneously with alignment regulating structures from the same material, the number of steps for manufacturing the common electrode substrate  10  is reduced to allow a reduction in the manufacturing cost. 
     The substrate for a liquid crystal display in the present mode for carrying out the invention and the liquid crystal display having the same will now be more specifically described with reference to Embodiments 1-1, 1-2 and 1-3. 
     Embodiment 1-1 
     A description will now be made with reference to  FIGS. 7 through 16B  on a substrate for a liquid crystal display according to Embodiment 1-1, a liquid crystal display having the same, and a method of manufacturing the same.  FIG. 7  is a conceptual illustration showing a TFT substrate  8  and a common electrode substrate  10  which are combined,  FIG. 7  showing three pixels in R, G and B. For example, the liquid crystal display of the present embodiment is an MVA type liquid crystal display, and  FIG. 7  also shows the positions of alignment regulating structures. Linear protrusions  28  are formed on the common electrode substrate  10  at an angle to edges of the pixel regions. On the TFT substrate  8 , slits  20  and finer slits  21  extending from the slits  20  substantially perpendicularly to the extending direction of the slits  20  are formed at an angle to the edges of the pixel regions. A plurality of finer slits  21  are formed at intervals smaller than the intervals between the slits  20  and linear protrusions  28 . When alignment regulating structures are formed at relatively small intervals, liquid crystal molecules having negative dielectric anisotropy are aligned in parallel with the direction in which the alignment regulating structures extend. Therefore, the alignment of liquid crystal molecules is more strongly regulated by forming the finer slits  21  perpendicular to the slits  20 . 
       FIG. 8  shows a section of the liquid crystal display taken along the line D-D in  FIG. 7 . As shown in  FIG. 8 , the TFT substrate  8  has an insulation film  24  formed on an entire surface of a glass substrate  12 . Drain bus lines  26  are formed on the insulation film  24 . Resin CF layers R, G and B ( FIG. 8  shows the layers G and B only) are formed on the drain bus lines  26 . Pixel electrodes  14  and the slits  20  which are cuts-off in a part of the pixel electrodes  14  are formed on the resin CF layers R, G and B.  FIG. 8  omits the finer slits  21 . The common electrode substrate  10  has a common electrode  18  formed on an entire surface of a glass substrate  12 . Linear protrusions  28  are formed on the common electrode  18 . A vertical alignment film (not shown) is formed on the pixel electrodes  14 , common electrode  18 , and linear protrusions  28 . A liquid crystal LC having negative dielectric anisotropy is sealed between the TFT substrate  8  and common electrode substrate  10 . 
       FIG. 9  shows a configuration in the vicinity of TFTs on the TFT substrate  8  of the present embodiment. As shown in  FIG. 9 , the TFT substrate  8  has a plurality of gate bus lines  25  ( FIG. 9  shows only one of them) extending in the horizontal direction in the figure and the plurality of drain bus lines  26  ( FIG. 9  shows three lines) extending in the vertical direction in the figure across the gate bus lines  25  on a glass substrate  12 . TFTs  42  are formed in the vicinity of intersections between the bus lines  25  and  26 . A TFT  42  is comprised of a drain electrode  44  that is a branch of a drain bus line  26 , a source electrode  46  provided in a face-to-face relationship with the drain electrode  44  with a predetermined gap kept between them, and a part (gate electrode) of a gate bus line  25  which overlaps the drain electrode  44  and source electrode  46 . An active semiconductor layer  52  is formed on the gate electrode, and a channel protection film  48  is formed on the same. The gate bus lines  25  and drain bus lines  26  define pixel regions, and resin CF layers R, G and B are formed in each of the pixel regions. A pixel electrode  14  is formed in each of the pixel regions. The pixel electrodes  14  are formed such that their edges in the horizontal direction in the figure overlap edges of the drain bus lines  26  when viewed in the direction perpendicular to the substrate surfaces.  FIG. 9  omits slits. 
       FIG. 10A  shows a section of the TFT substrate  8  taken along the line E-E in  FIG. 9 , and  FIG. 10B  shows a section of the TFT substrate  8  taken along the line F-F in  FIG. 9 . As shown in  FIGS. 10A and 10B , the resin CF layers R, G and B are formed on the TFTs  42  and drain bus lines  26 . The pixel electrodes  14  are formed on the resin CF layers R, G and B. The pixel electrodes  14  are formed such that their edges overlap the edges of the drain bus lines  26  when viewed in the direction perpendicular to the substrate surfaces. 
     A method of manufacturing the liquid crystal display of the present embodiment will now be described with reference to  FIGS. 11A through 16B .  FIGS. 11A through 16B  are sectional views taken at manufacturing steps showing the method of manufacturing the liquid crystal display of the present embodiment. FIGS.  11 A,  12 A,  13 A,  14 A,  15 A and  16 A show the section of the TFT substrate  8  taken along the line E-E in  FIG. 9 , and  FIGS. 11B ,  12 B,  13 B,  14 B,  15 B and  16 B show the section of the TFT substrate  8  taken along the line F-F in  FIG. 9 . For example, as shown in  FIGS. 11A and 11B , an aluminum (Al) layer having a thickness of 100 nm and a titanium (Ti) layer having a thickness of 50 nm are formed in the same order on an entire surface of a glass substrate  12  and are patterned to form gate bus lines  25 . The patterning is carried out using a photolithographic process in which a predetermined resist pattern is formed on the layers to be patterned; the layers to be patterned are etched using the resist pattern as an etching mask; and the resist pattern is then removed. 
     Next, for example, a silicon nitride film (SiN film) having a thickness of 350 nm, an a-Si layer  52 ′ having a thickness of 30 nm, and a SiN film having a thickness of 120 nm are continuously formed as shown in  FIGS. 12A and 12B . Then, a channel protection film  48  to serve as an etching stopper is formed on a self-alignment basis by patterning the same through backside exposure. For example, an n + a-Si layer having a thickness of 30 nm, a Ti layer having a thickness of 20 nm, an aluminum layer having a thickness of 75 nm, and a Ti layer having a thickness of 40 nm are then formed as shown in  FIGS. 13A and 13B  and are patterned using the channel protection film  48  as an etching stopper to form drain electrodes  44 , source electrodes  46 , and drain bus lines  26 . TFTs  42  are completed through the above-described steps. 
     Next, as shown in  FIGS. 14A and 14B , for example, a red resist having a photosensitive pigment dispersed therein is applied to a thickness of 3.0 μm and patterned. Thereafter, post-baking is performed to form resin CF layers R in predetermined pixel regions, the layers having contact holes  50  formed above the source electrodes  46 . 
     Next, as shown in  FIGS. 15A and 15B , for example, a blue resist having a photosensitive pigment dispersed therein is applied to a thickness of 3.0 μm and patterned. Thereafter, post-baking is performed to form resin CF layers B in predetermined pixel regions. Similarly, as shown in  FIGS. 16A and 16B , resin CF layers G are formed in predetermined pixel regions. Next, an ITO film having a thickness of 70 nm for example is formed on the entire surface and patterned to form pixel electrodes  14  such that their edges in the horizontal direction in the figures overlap edges of the drain bus lines  26  when viewed in the direction perpendicular to the substrate surfaces. A TFT substrate  8  as shown in  FIGS. 9 through 10B  is completed through the above-described steps. 
     While the resin CF layers R, G and B are formed directly on source/drain forming layers such as the drain electrodes  44 , source electrodes  46  and drain bus lines  26  in the present embodiment, a protective film may be formed on the source/drain forming layers and the resin CF layers R, G and B may be formed on the protective film. Alternatively, a protective film may be formed on the resin CF layers R, G and B, and the pixel electrodes  14  may be formed on the protective film. Obviously, the TFTs  42  and resin CF layers R, G and B may be formed and manufactured using materials and steps other than those described above. 
     Referring to alignment regulating structures, the slits  20  and finer slits  21  are formed on the TFT substrate  8 , and the linear protrusions  28  are formed on the common electrode substrate  10  in the present embodiment. However, they may be used in different combinations. The present embodiment provides effects similar to those achieved with the above-described first basic configuration. 
     Embodiment 1-2 
     A description will now be made with reference to  FIGS. 17 ,  18  and  42  on a substrate for a liquid crystal display according to Embodiment 1-2 and a liquid crystal display having the same.  FIG. 17  is a sectional view of the liquid crystal display of the present embodiment showing a configuration thereof,  FIG. 17  showing a section similar to that shown in  FIG. 8 . As shown in  FIG. 17 , the liquid crystal display of the present embodiment has dielectric layers  56  which are formed above slits  20  in a TFT substrate  8  and which serve as alignment regulating structures for improving response characteristics of liquid crystal molecules to half tones. The dielectric layers  56  are formed from a photoresist or the like. 
       FIG. 18  is a sectional view of the liquid crystal display of the present embodiment showing a configuration of the same,  FIG. 18  showing a section similar to that shown in  FIG. 4 . As shown in  FIG. 18 , in the liquid crystal display of the present embodiment, resin CF layers R, B and G are formed in the same order in the vicinity of intersections between gate bus lines  25  and drain bus lines  26  on the TFT substrate  8 . A protrusion  29  which does not function as an alignment regulating structure is formed on a common electrode  18  on a common electrode substrate  10 . A columnar spacer  30  for maintaining a cell gap is formed by a gate bus line  25  on the TFT substrate  8 , an insulation film  24 , a drain bus line  26 , resin CF layers R, G and B, and the protrusion  29  on the common electrode substrate  10 . 
     The columnar spacer  30  is not limited to the above-described configuration and may be constituted by other layers. For example, it is possible to use a resin layer that is formed simultaneously with the dielectric layers  56  on the resin CF layer B from the same material as that of the layers  56 . In this case, it is not necessary to form the protrusion  29  on the common electrode substrate  10 . The TFTs  42 , resin CF layers R, G and B, and so on may be formed and manufactured using materials and steps other than those described above. The alignment regulating structures respectively formed on the TFT substrate  8  and common electrode substrate  10  may be in other combinations. The present embodiment provides the same effects as those achieved with the above-described second basic configuration. 
       FIG. 42  is a sectional view of the liquid crystal display of the present embodiment showing a modification of the same, and  FIG. 42  shows a section similar to that shown in  FIG. 4 . As shown in  FIG. 42 , in the liquid crystal display of the present modification, a columnar spacer  30  is structured by only resin CF layers R, B and G laminated in the same order in the vicinity of intersections between gate bus lines  25  and drain bus lines  26  on the TFT substrate  8 . Thus, the columnar spacer  30  may be formed using neither the protrusion  29  on the common electrode substrate  10  nor the dielectric layers  56  on the TFT substrate  8 . 
     It is desirable for the CF-on-TFT structured MVA-LCD having another alignment regulation structure besides the protrusion  29  to use this structure. In the TN mode LCD, for example, it is necessary to consider the laminating accuracy at the time of laminating the resin CF layers, the panel attaching accuracy and the necessary area for obtaining the enough height of the layer while the columnar spacer is formed by laminating the resin CF layers. It is necessary to enlarge the sectional area of resin CF layers for forming the columnar spacer, therefore, the problem that the aperture ratio of pixel has to decrease is caused to the TN mode LCD. 
     On the other hand, there is no need to consider the panel attaching accuracy in the CF-on-TFT structure. However, the aperture ratio of pixel is decreased by forming the BM layer to shade the defective alignment of the liquid crystal in the vicinity of columnar spacer. 
     On the contrary, since the CF-on-TFT structured MVA-LCD has a normally black mode which always becomes black on the part of the display where the pixel electrode does not exist, there is no need to form BM layers. Therefore, it is possible to suppress the decreasing of aperture ratio of pixel. Moreover, since it is no need to consider the panel attaching accuracy and the defective alignment of the liquid crystal in the vicinity of columnar spacer, it is possible to form the columnar spacer with suppressing the decreasing of aperture ratio of pixel. 
     Embodiment 1-3 
     A description will now be made with reference to  FIGS. 19 through 22  on a substrate for a liquid crystal display according to Embodiment 1-3, a liquid crystal display having the same, and a method of manufacturing the same.  FIG. 19  shows a configuration of the substrate for a liquid crystal display of the present embodiment and corresponds to  FIG. 6A .  FIG. 20  shows a section of the substrate for a liquid crystal display taken along the line G-G in  FIG. 19  and corresponds to  FIG. 6B . As shown in  FIGS. 19 and 20 , a common electrode  18  is formed on a glass substrate  12  in a display area  38  and a frame region  40  on a common electrode substrate  10 . Linear protrusions  28  are formed on the common electrode  18  in the display area  38  at an angle to edges of the display area  38 . The linear protrusions  28  are formed by a bottom layer made of chromium (Cr) that is a light-blocking metal and a top layer which is a resist layer used for patterning Cr. A frame pattern  34  for shielding edges of the display area  38  from light is formed in the frame region  40 . A cross-shaped alignment mark  36  used for combining the common electrode substrate with a TFT substrate (which is not shown in  FIGS. 19 and 20 ) in a face-to-face relationship is formed on the glass substrate  10  on the left side of the frame region  40  in the figure. The frame pattern  34  and alignment mark  36  are formed simultaneously with the linear protrusions  28  from the same material. 
     A method of manufacturing the substrate for a liquid crystal display of the present embodiment will now be described with reference to  FIGS. 21 and 22 . For example, an ITO film having a thickness of 100 nm is first formed on an entire surface of the glass substrate  12  and patterned as shown in  FIG. 21  to form the common electrode  18 . For example, a Cr film having a thickness of 100 nm is then formed on the entire surface as shown in  FIG. 22 . Next, a resist is applied to the entire surface, exposed, and developed to form a predetermined resist pattern. Then, Cr is etched using the resist pattern as an etching mask to form the bottom layer of the linear protrusions  28 , the frame pattern  34 , and the alignment mark  36 . The resist pattern is then hardened through post-baking to form the top layer of the linear protrusions  28 . The common electrode substrate  10  of the present embodiment is completed through the above-described steps. 
     While a metal layer capable of blocking light such as Cr is used to shield the frame region  40  from light or to allow the alignment mark  36  to be visually recognized and a resist is used to form the linear protrusions  28  in the present embodiment, the need for a metal layer for blocking light can be eliminated by using a black resist for forming an opaque film as the resist layer as shown in  FIGS. 5 through 6B . An MVA type liquid crystal display is in the normally black mode, and such a black resist will sufficiently work if it has an OD-value (optical density) on the order of 2.0. 
     As thus described, the present embodiment makes it possible to provide a liquid crystal display having high luminance and preferable display characteristics. 
     Second Mode for Carrying Out the Invention 
     A description will now be made with reference to  FIGS. 23 and 24  on a substrate for a liquid crystal display on a second mode for carrying out the invention, a liquid crystal display having the same, and a method of manufacturing the same. 
     Color liquid crystal displays are used as monitors and displays of notebook PCs, PDAs (personal digital assistants), and the like, and there are recent demands for further reductions in the weight of such displays. In general, glass substrates occupy a great percentage of the weight of a liquid crystal display compared to other members. For example, glass substrates having a thickness of 0.7 mm occupy about 40% of the weight of a liquid crystal display. It is a common and effective approach to reduce the weight of glass substrates in order to reduce the weight of a liquid crystal display. 
     One means for reducing the weight of a glass is to reduce the thickness of the same. However, it is difficult to form TFTs and color filters on a thin glass through highly accurate patterning, and a problem arises in that there is a limit on patterning accuracy. When glass substrates having different characteristics are used as a TFT substrate and a common electrode substrate provided in a face-to-face relationship, a problem arises in that it is difficult to combine them together because of deformation of the substrates attributable to heat or the like. Although the two substrates may be polished to reduce the thicknesses of them after the liquid crystal panel is completed, a problem arises in that the manufacturing cost is increased. 
     Another method for reducing the weight of substrates is to use plastic substrates instead of glass substrates. However, this results in the same problem as encountered in the case of thin glass substrates in that it is difficult to form TFTs and color filters for which highly accurate patterning is required. Further, since such substrates are soft, a problem arises in that they may be insufficient in resistance to pressures applied by fingers and the like depending on the intended usage. It is an object of the present mode for carrying out the invention to provide a lightweight liquid crystal display having high reliability. 
     Taking those problems into consideration, in the present mode for carrying out the invention, TFTs and color filters are formed on one substrate. Since this eliminates the need for highly accurate patterning on another substrate, thin glass substrates, plastic substrates or the like may be freely chosen. Further, columnar spacers for maintaining a cell gap are formed on a substrate in advance in the present mode for carrying out the invention. This makes it possible to provide a stable cell gap and to improve anti-pressure properties. 
     A more specific description will be made on substrates for a liquid crystal display in the present mode for carrying out the invention, liquid crystal displays having the same, and methods of manufacturing the same with reference to Embodiments 2-1 and 2-2. 
     Embodiment 2-1 
     A liquid crystal display according to Embodiment 2-1 will now be described. A TFT substrate  8  of the liquid crystal display of the present embodiment has a configuration similar to that of the TFT substrate  8  in the first mode for carrying out the invention shown in  FIGS. 9 through 10B . 
       FIG. 23  corresponds to  FIG. 10A  and shows a section of the liquid crystal display of the present embodiment. As shown in  FIG. 23 , the liquid crystal display of the present embodiment is formed by combining a TFT substrate  8  and a common electrode substrate  10  having a thickness smaller than that of the TFT substrate  8  with a predetermined cell gap kept between them. The common electrode substrate  10  has a common electrode  18  formed on a glass substrate  12 ′ having a thickness smaller than that of a glass substrate  12  to serve as the TFT substrate  8 . 
     A method of manufacturing a substrate for a liquid crystal display according to the present embodiment and a liquid crystal display having the same will now be briefly described. A method of manufacturing the TFT substrate  8  will not be described because it is similar to that in the first mode for carrying out the invention shown in  FIGS. 11A through 16B . As shown in  FIG. 23 , a glass substrate  12 ′ made of non alkali glass which is the same material as that of a glass substrate  12  to serve as the TFT substrate  8  and which has a thickness smaller than that of the glass substrate  12 , e.g., 0.2 mm, is used as the common electrode substrate  10 . For example, an ITO film having a thickness of 100 nm is formed on an entire surface of the glass substrate  12 ′ and patterned to form a common electrode  18 . This step completes the common electrode substrate  10 . 
     Thereafter, alignment films are formed on surfaces of the substrates  8  and  10  in a face-to-face relationship and are rubbed. Next, a sealant is applied, and spacers are dispersed. The substrates  8  and  10  are then combined and cut into each panel. Next, a liquid crystal is injected through a liquid crystal injection port and sealed, and polarizers are applied. A liquid crystal display according to the present embodiment is completed through the above-described steps. 
     While non alkali glass having a thickness of 0.2 mm is used as the glass substrate  12 ′ of the present embodiment, glass having a specific density different from that of the glass substrate  12  may be used instead. Soda lime glass including alkaline components may be used to achieve a greater reduction in the manufacturing cost. For example, the glass includes 1% or more alkaline components. However, when glass including alkaline components is used in a liquid crystal display having TFTs  42  of the channel-etching type or the like having exposed active semiconductor layers  52 , since the TFTs  42  can be contaminated by alkali, the TFTs  42  are preferably protected with a protective film or the like. Such a problem will not occur when glass including alkaline components is used in a liquid crystal display having TFTs  42  with a channel protection film. 
     In the present embodiment, resin CF layers R, G and B are formed on the TFT substrate  8  to allow the use of a substrate made of glass or plastic as the common electrode substrate  10 . This makes it possible to provide a lightweight and reliable liquid crystal display. Resistance to pressures applied by fingers and the like can be improved by providing a thicker substrate on the side of the display screen. 
     Embodiment 2-2 
     A liquid crystal display according to Embodiment 2-2 will now be described with reference to  FIG. 24 .  FIG. 24  is a sectional view of the liquid crystal display of the present embodiment showing a configuration of the same. As shown in  FIG. 24 , a common electrode substrate  10  of the liquid crystal display of the present embodiment has a glass substrate  12 ′ having a thickness smaller than that of a glass substrate  12  to serve as a TFT substrate  8  just as in the liquid crystal display of Embodiment 2-1. 
     Resin CF layers B, G and R are formed in the same order on the TFT substrate  8 , and resin layers  60  made of photosensitive acrylic resin are formed on the same to form columnar spacers  30  for maintaining a cell gap. The layers of the columnar spacers  30  may be in other configurations, and the layers may be formed in any order. In the case of an MVA type liquid crystal display, the resin layers  60  may be formed simultaneously with linear protrusions as alignment regulating structures from the same material as that of the latter. 
     In the present embodiment, the use of the columnar spacers  30  prevent any variation of the cell gap attributable to spherical spacers or the like dispersed on a substrate surface which can be stranded on alignment regulating structures, and this makes it possible to provide a stable cell gap. Further, since the columnar spacers  30  are provided on the substrate surface uniformly and in a high density, anti-pressure properties are improved. For this reason, a reliable liquid crystal display can be provided even when the common electrode substrate  10  is provided on the display screen side. When the TFT substrate  8  is provided on the display screen side, since reflection is increased by the metal layer, it is desirable to use a low-reflection multi-layer metal at least on the side of the metal layer facing the glass substrate  12 . 
     Effects of the present mode for carrying out the invention will now be specifically described in comparison to those of a conventional liquid crystal display. Table 1 specifies two substrates A1 and B1 that form a part of a conventional liquid crystal display. Resin CF layers R, G and B are formed on the substrate A1, and TFTs  42  are formed on the substrate B1. The substrates A1 and B1 are made of NA35 glass. The substrates A1 and B1 have a thickness of 0.7 mm and a density of 2.50 g/cm 3 . 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Components 
                 Panel 
               
               
                   
                   
                 Thickness 
                 Density 
                 on 
                 Weight 
               
               
                   
                 Material 
                 (mm) 
                 (g/cm 3 ) 
                 Substrates 
                 Percentage 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Substrate 
                 NA35 glass 
                 0.7 
                 2.50 
                 CF 
                 1 
               
               
                 A1 
               
               
                 Substrate 
                 NA35 glass 
                 0.7 
                 2.50 
                 TFT 
               
               
                 B1 
               
               
                   
               
             
          
         
       
     
     Table 2 specifies two substrates A2 and B2 that form a part of another conventional liquid crystal display. NA35 glass having a density of 2.50 g/cm 3  is used for both of the substrates A2 and B2 similarly to the substrates A1 and B1. After they are combined, each of the substrates A2 and B2 is polished to a thickness of 0.5 mm. Resin CF layers R, G and B are formed on the substrate A2, and TFTs  42  are formed on the substrate B2. Although a reduction in weight has been achieved in the resultant panel in that it has a weight percentage of 0.71 (hereinafter referred to as “panel weight percentage”) where it is assumed that a liquid crystal panel obtained by combining the substrates A1 and B1 shown in Table 1 has a weight percentage of 1, the panel is more expensive because of an increase in the manufacturing cost. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Components 
                 Panel 
               
               
                   
                   
                 Thickness 
                 Density 
                 on 
                 Weight 
               
               
                   
                 Material 
                 (mm) 
                 (g/cm 3 ) 
                 Substrates 
                 Percentage 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Substrate 
                 NA35 glass 
                 0.5 
                 2.50 
                 CF 
                 0.71 
               
               
                 A2 
               
               
                 Substrate 
                 NA35 glass 
                 0.5 
                 2.50 
                 TFT 
               
               
                 B2 
               
               
                   
               
             
          
         
       
     
     Table 3 specifies two substrates A3 and B3 that form a part of a liquid crystal display according to the present embodiment. NA35 glass having a thickness of 0.7 mm and a density of 2.50 g/cm 3  is used for the substrate B3 similarly to the substrate B1. TFTs  42  and resin CF layers R, G and B are formed on the substrate B3. Asahi AS glass that is alkali glass having a thickness of 0.2 mm and a density of 2.49 g/cm 3  is used for the substrate A3. The resultant panel has a weight percentage of 0.64 which represents a weight smaller than that of the panel shown in Table 2. The substrate A3 may be made of any type of glass that is lighter than the substrate B3. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Components 
                 Panel 
               
               
                   
                   
                 Thickness 
                 Density 
                 on 
                 Weight 
               
               
                   
                 Material 
                 (mm) 
                 (g/cm 3 ) 
                 Substrates 
                 Percentage 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Substrate 
                 Asahi AS 
                 0.2 
                 2.49 
                 — 
                 0.64 
               
               
                 A3 
               
               
                 Substrate 
                 NA35 glass 
                 0.7 
                 2.50 
                 TFT 
               
               
                 B3 
                   
                   
                   
                 CF 
               
               
                   
               
             
          
         
       
     
     Table 4 specifies two substrates A4 and B4 that form a part of another liquid crystal display according to the present embodiment. NA35 glass having a thickness of 0.7 mm and a density of 2.50 g/cm 3  is used for the substrate B4 similarly to the substrate B1. TFTs and color filters are formed on the substrate B4. Polyethersulfone (PES) having a thickness of 0.2 mm and a density of 1.40 g/cm 3  is used for the substrate A4. The resultant panel has a weight percentage of 0.58 which represents a greater reduction in weight than that of the panel shown in Table 3. The material of the substrate A4 is not limited to PES and may be any plastic such as polycarbonate (PC) or polyacrylate (PAR). 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Components 
                 Panel 
               
               
                   
                   
                 Thickness 
                 Density 
                 on 
                 Weight 
               
               
                   
                 Material 
                 (mm) 
                 (g/cm 3 ) 
                 Substrates 
                 Percentage 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Substrate 
                 PES 
                 0.2 
                 1.40 
                 — 
                 0.58 
               
               
                 A4 
               
               
                 Substrate 
                 NA35 glass 
                 0.7 
                 2.50 
                 TFT 
               
               
                 B4 
                   
                   
                   
                 CF 
               
               
                   
               
             
          
         
       
     
     As described above, the resin CF layers R, B and G are formed under the pixel electrodes  14  in the present mode for carrying out the invention. This eliminates any need for highly accurate patterning of the common electrode substrate  10  and also eliminates any need for accurate alignment when combining it with the TFT substrate  8 . Since this makes it possible to use a glass substrate, plastic substrate, or the like having a small thickness as the common electrode substrate  10 , a lightweight and reliable liquid crystal display can be provided. Further, since there is no need for polishing the TFT substrate  8  and common electrode substrate  10  to reduce their thickness after combining them, there is no increase in manufacturing steps and manufacturing cost. 
     Third Mode for Carrying Out the Invention 
     A description will now be made with reference to  FIGS. 25 through 34B  on a substrate for a liquid crystal display, a liquid crystal display having the same, and a method of manufacturing the same. 
     In the case of a substrate for a liquid crystal display having a structure in which resin CF layers R, G and B are formed on a TFT substrate  8  (CF-on-TFT structure) as in the first mode for carrying out the invention, the numerical aperture can be improved because the resin CF layers R, G and B are formed under pixel electrodes  14 . This improves the transmittance of the panel and makes it possible to improve the luminance of the liquid crystal display. 
     However, in a substrate for a liquid crystal display having the CF-on-TFT structure as in the first mode for carrying out the invention, if the top of the source/drain metal layers which are the top layer (A gate metal layer may be also included in the top layer in the case of a top gate structure. Hereinafter, such a configuration will be also simply referred to as “source/drain metal layers”.) is not covered by a protective film (passivation film) when the TFTs  42  are formed, the source/drain metal layers can be corroded by a CF developer when the resin CF layers R, G and B formed above the same are patterned, which results in a problem in that the resistance of the bus lines constituted by the metal layers is increased and in that the bus lines are broken. Another problem arises in that the source electrodes  44  and drain electrodes  46  are removed as a result of corrosion to expose the active semiconductor layer  52  which can then be contaminated as a result of contact with the CF developer. When a protective film is formed on the source/drain metal layer using a CVD apparatus, another problem arises in that there will be an increase in the number of manufacturing steps. It is an object of the present mode for carrying out the invention to provide a substrate for a liquid crystal display with which an inexpensive and reliable display can be provided, a liquid crystal display having the same, and a method of manufacturing the same. 
     In the present mode for carrying out the invention, the above-mentioned problems are solved by covering source/drain metal layers with resin CF layers R, G and B which are first formed or black matrix resin formed under the resin CF layers R, G and B or resin that formed a part of columnar spacers  30 . 
     A more specific description will now be made with reference to Embodiment 3-1 and Embodiment 3-2 on substrates for a liquid crystal display in the present invention, liquid crystal displays having the same, and methods of manufacturing the same. 
     Embodiment 3-1 
     A description will be first made on a substrate for a liquid crystal display according to Embodiment 3-1, a liquid crystal display having the same, and a method of manufacturing the same with reference to  FIGS. 25 through 33B .  FIG. 25  shows a configuration of the substrate for a liquid crystal display according to the present embodiment (CF layers are omitted in the figure).  FIG. 26A  shows a section of the substrate for a liquid crystal display taken along the line J-J in  FIG. 25 , and  FIG. 26B  shows a section of the substrate for a liquid crystal display taken along the line K-K in  FIG. 25 . As shown in  FIGS. 26A and 26B , in the substrate for a liquid crystal display, a black matrix is formed by forming two resin CF layers in different colors at edges of pixel regions. Throughout the black matrix formed by overlapping two resin CF layers, a resin CF layer R is located at the bottom thereof. The resin CF layers R are formed such that they cover all of source/drain metal layers such as drain bus lines  26 . A pixel electrode  14  is formed with a slit  20  extending in parallel with an edge of the pixel region and a plurality of finer slits  21  diagonally extending from the slit  20 . The substrate for a liquid crystal display of the present embodiment has a liquid crystal in which a polymeric structure is formed by curing ultraviolet monomers through irradiation with ultraviolet light. 
     A method of manufacturing the substrate for a display of the present embodiment will now be described with reference to  FIGS. 27 through 33B .  FIGS. 27 through 30  illustrate a method of manufacturing the substrate for a liquid crystal display of the present embodiment.  FIGS. 31A through 33B  are sectional views at manufacturing steps illustrating the method of manufacturing the substrate for a liquid crystal display of the present embodiment.  FIGS. 31A ,  32 A and  33 A show a section similar to that in  FIG. 26A , and  FIGS. 31B ,  32 B and  33 B show a section similar to that in  FIG. 26B . Steps up to the formation of TFTs  42  and drain bus lines  26  on a glass substrate  12  will not be described because they are similar to those in the method of manufacturing the substrate for a liquid crystal display of Embodiment 1-1 shown in  FIGS. 11A through 13B . 
     At steps as shown in  FIGS. 11A through 13B , a plurality of gate bus lines  25  extending in the horizontal direction in the figures and drain bus lines  26  extending in the vertical direction in the figures across the gate bus lines  25  are formed (see  FIG. 27 ). TFTs  42  are formed in the vicinity of intersections between the gate bus lines  25  and drain bus lines  26 . The gate bus lines  25  and drain bus lines  26  define pixel regions. Storage capacity bus lines (auxiliary capacity electrodes)  62  extending through the pixel regions substantially in the middle thereof and substantially in parallel with the gate bus lines  25  are formed in the same layer as that of the gate bus lines  25 . A storage capacity electrode (intermediate electrode)  64  for each pixel region is formed on the storage capacity bus line  62  in the same layer as that of the drain bus lines  26 . 
     Next, a photosensitive red resist having a pigment dispersed therein is applied to a thickness of 1.5 μm for example and patterned. It is thereafter subjected to post-baking to form first resin CF layers R on pixel regions to display red, the TFTs  42 , the gate bus lines  25 , the drain bus lines  26  and the storage capacity bus lines  62  as shown in  FIGS. 28 ,  31 A and  31 B. At this time, the drain electrodes  44 , source electrodes  46  and drain bus lines  26  that are top metal layers are covered by the resin CF layers R. 
     Next, a green resist is applied to a thickness of 1.5 μm for example and patterned. It is thereafter subjected to post-baking to form second resin CF layers G on pixel regions to display green and on the drain bus lines  26  located adjacently to such pixel regions on the left of the same, as shown in  FIGS. 29 ,  32 A and  32 B. At this time, a black matrix is formed by overlapping two resin CF layers on the TFTs  42  in the pixel regions, the gate bus lines  25  adjacent to the pixel regions, the storage capacity bus lines  62  in the pixel regions, and the drain bus lines  26  located adjacently to the pixel regions on the left of the same. 
     Next, a blue resist is applied to a thickness of 1.5 μm for example and patterned. It is thereafter subjected to post baking to form third resin CF layers B on pixel regions to display blue, the drain bus lines  26  located adjacently to such pixel regions on both sides of the same, and the TFTs  42  located adjacently to the pixel regions on the right of the same, as shown in  FIGS. 30 ,  33 A and  33 B. At this time, a black matrix is formed by overlapping two resin CF layers on the TFTs  42  in the pixel regions located adjacently to the pixel regions on the right of the same, the gate bus lines  25  adjacent to the pixel regions, the storage capacity bus lines  62  in the pixel regions, and the drain bus lines  26  located adjacently to the pixel regions on both sides of the same. 
     Thereafter, an ITO film having a thickness of 70 nm for example is formed on the entire surface and patterned to form a pixel electrode  14 , a slit  20  and finer slits  21  in each pixel region, which completes a substrate for a liquid crystal display as shown in  FIGS. 25 through 26B . 
     Next, a vertical alignment film is applied to each of surfaces of a common electrode substrate formed with a common electrode made of ITO for example and the above-described substrate for a liquid crystal display, the surfaces facing each other. For example, spherical spacers are then dispersed on one of the substrates, and a sealant is applied to the periphery of the other substrate. Subsequently, the two substrates are put together, and a liquid crystal is injected into a gap between the substrates. Referring to the liquid crystal, for example, a negative liquid crystal having negative dielectric anisotropy added with 0.2% ultraviolet-curing monomer by weight may be used. Next, for example, a tone voltage of 10 V dc is applied to the drain bus lines  26 , and a common voltage of 5 V dc is applied to the common electrode. Subsequently, for example, a gate voltage of 30 V dc is applied to the gate bus lines  25  to tilt the liquid crystal in the liquid crystal panel which is then irradiated with ultraviolet light of 2000 mJ having a wavelength in the range from 300 to 450 nm from the opposite substrate side. As a result, the ultraviolet-curing monomers are cured to form a polymeric structure in the liquid crystal in the liquid crystal panel, which causes the liquid crystal molecules (represented by columns in the drawings) to be tilted in four directions from their states when no voltage is applied, as shown in  FIG. 25 . In the present embodiment, the pre-tilt angle of the liquid crystal molecules is 86 deg. Thereafter, polarizers are applied to the two substrates to complete the liquid crystal display of the present embodiment. 
     Embodiment 3-2 
     A description will be first made on a substrate for a liquid crystal display according to Embodiment 3-2, a liquid crystal display having the same, and a method of manufacturing the same with reference to  FIGS. 34A and 34B .  FIGS. 34A and 34B  are sectional views of the substrate for a liquid crystal display of the present embodiment showing a configuration of the same. While the substrate for a liquid crystal display of Embodiment 3-1 has TFTs  42  with a channel protection film, the substrate for a liquid crystal display of the present embodiment has channel-etched TFTs  66  as shown in  FIGS. 34A and 34B . 
     A description will now be made on a substrate for a liquid crystal display according to the present embodiment, a liquid crystal display having the same, and a method of manufacturing the same. First, for example, an Al layer having a thickness of 100 nm and a Ti layer having a thickness of 50 nm are formed in the same order on an entire surface of a glass substrate  12  and are patterned to form gate bus lines  25  and storage capacity bus lines. Next, for example, a SiN film having a thickness of 350 nm, an a-Si layer having a thickness of 120 nm, and an n + a-Si layer having a thickness of 30 nm are continuously formed. Next, the n + a-Si layer and a-Si layer are patterned in the form of islands to form active semiconductor layers  52 ′ and n-type semiconductor layers (not shown) located on the same. Next, for example, a MoN film having a thickness of 50 nm, an Al film having a thickness of 150 nm, a MoN film having a thickness of 70 nm, and a Mo film having a thickness of 10 nm are continuously formed and patterned, and element isolation is then carried out to form source electrodes  46 , drain electrodes  44 , and storage capacity electrodes. The channel-etched TFTs  66  are completed through the above-described steps. Subsequent steps are not illustrated and described because they are similar to those in the method of manufacturing the liquid crystal display of Embodiment 3-1 shown in  FIGS. 27 through 33B . 
     A method of manufacturing a substrate for a liquid crystal display according to another embodiment of the invention will now be described. Although not shown, features having the same functions and operations as those of the features shown in  FIGS. 34A and 34B  will be described using like reference numbers. The substrate for a liquid crystal display of the present embodiment has top-gate type TFTs  42 . First, for example, a Ti layer having a thickness of 20 nm, an Al layer having a thickness of 75 nm, a Ti layer having a thickness of 40 nm, and an n + a-Si layer having a thickness of 30 nm are formed on a glass substrate  12  and are patterned to form drain electrodes  44  and source electrodes  46 . Next, for example, an a-Si layer having a thickness of 30 nm, a SiN film having a thickness of 350 nm, and an Al layer having a thickness of 100 nm are formed and patterned to form active semiconductor layers  52 ′, an insulation film  24 , and gate bus lines  25  simultaneously. The semiconductor layers  52 ′, insulation films  24 , and gate bus lines  25  may be sequentially formed instead of forming them simultaneously. The top-gate type TFTs  42  are completed through the above-described steps. Although storage capacity bus lines  62  and storage capacity electrodes  64  are not formed in the present embodiment, they may be obviously formed. Subsequent steps will not be described because they are substantially similar to those of the method of manufacturing the liquid crystal display of Embodiment 3-1 shown in  FIGS. 27 through 33B . In the present embodiment, since the top metal layer is the gate metal layer, the gate metal layer is coated with the resin CF layer that is formed first. 
     A method of manufacturing a substrate for a liquid crystal display according to still another embodiment of the invention will now be described. Although not shown, features having the same functions and operations as those of the features shown in  FIGS. 34A and 34B  will be described using like reference numbers. The substrate for a liquid crystal display of the present embodiment has TFTs in which polysilicon (p-Si) is used for active semiconductor layers  52 . First, for example, a SiN film having a thickness of 50 nm, a SiO 2  film having a thickness of 200 nm, and an a-Si layer having a thickness of 40 nm are formed on a glass substrate  12 , and the resultant substrate is subjected to a heat treatment in an annealing oven to be dehydrogenized. Next, the a-Si layer is irradiated with a predetermined laser to be crystallized and is then patterned to form a p-Si layer. Next, for example, a SiO 2  film having a thickness of 110 nm and a AlNd film having a thickness of 300 nm are formed and patterned to form insulation films (gate insulation films)  24  and gate bus lines  25 . 
     The p-Si layer is then doped with phosphorus (P) ions to form N-type regions selectively, and the p-Si layer is subsequently doped with boron (B) ions to form P-type regions selectively. Next, for example, a SiO 2  film having a thickness of 60 nm and a SiN film having a thickness of 370 nm are formed to form an interlayer insulation film. The interlayer insulation film on the high density impurity regions is then removed to form contact holes. Next, for example, a Ti layer having a thickness of 100 nm, an Al layer having a thickness of 200 nm, and a Ti layer having a thickness of 100 nm are formed and patterned to form drain electrodes  44  and source electrodes  46 . TFTs  70  in which p-Si is used for active semiconductor layers are completed through the above-described steps. Although storage capacity bus lines and storage capacity electrodes are not formed in the present embodiment, it is obviously possible to form storage capacity bus lines simultaneously with the gate bus lines from the same material and to form storage capacity electrodes simultaneously with the source and drain electrodes from the same material. 
     While the top metal layer is covered by the resin CF layer that is formed first in the above-described embodiment, the top metal layer may be covered by resin to serve as a black matrix or resin to serve as a part of columnar spacers before the resin CF layer is formed. While a black matrix is formed by laminating two resin CF layers, i.e., the first and second resin CF layers or the first and third resin CF layers on the TFTs  42  and bus lines  25 ,  26 , and  62  in the above-described embodiment, the black matrix may be formed by staking all of the three resin CF layers. It is not necessary to form the resin CF layers if black matrix is formed at a different step. 
     Further, while the pixel electrodes  14  in the above-described embodiment are formed with the slits  20  and finer slits  21  because the described example is a polymer-fixed liquid crystal display, other alignment regulating structures may be used. While the entire top metal layer is covered with a resin CF layer in the above-described embodiment, only edge portions of the top metal layer may be covered. Obviously, the substrate for a liquid crystal display may have a structure which does not include the storage capacity bus lines  62  made of the same material as that of the gate bus lines  25  and the storage capacity electrodes  64  made of the same material as that of the source electrodes  44  and drain electrodes  46 . 
     As described above, in the present mode for carrying out the invention, the source/drain metal layer (a gate metal layer in the case of a top-gate structure) is covered by the resin CF layer that is formed first. This prevents the source/drain layer from being corroded by a CF developer when the resin CF layers are patterned. Since this prevents any increase in the bus line resistance and breakage of the bus lines, an improved yield of manufacture can be achieved. Further, the active semiconductor layers  52  will not be contaminated. There is no increase in the number of manufacturing steps because it is not necessary to form a protective film on the source/drain metal layer. 
     The liquid crystal display in the present mode for carrying out the invention is free from any reduction or irregularity of luminance attributable to a reduction in retention and burning of patterns. Since the resin CF layers R, G and B formed on the TFTs  42  absorb ultraviolet light applied to form a polymeric structure, there will be no display defect such as cross-talk or a flicker which is otherwise caused by abnormality in the characteristics of the TFTs  42 . 
     Since the alignment of liquid crystal molecules is separated in four directions in the liquid crystal display in the present mode for carrying out the invention, a wide viewing angle is provided, and high contrast can be achieved by vertical alignment. Further, since the tilting direction of liquid crystal molecules is regulated by a polymeric structure, high speed response can be achieved. 
     The invention is not limited to the above-described modes for carrying out the same may be modified in various ways. 
     For example, the pixel electrodes  14  are formed directly on the resin CF layers R, G and B in the above-described modes for carrying out the invention. The invention is not limited to such a configuration, and a protective film made of an organic or inorganic material may be formed on the resin CF layers R, G and B, and the pixel electrodes  14  may be formed on the protective film. The formation of such a protective film makes it possible to prevent the liquid crystal from being contaminated by the material of the resin CF layers and to prevent line breakage through a reduction in steps at the pixel electrodes  14 . The resin CF layers R, G and B may be formed in any order, and the materials, configurations and thicknesses of the TFTs  42  and resin CF layers R, G and B are not limited to those described in the above modes for carrying out the invention. 
     While transmission type liquid crystal displays have been referred to in the above-described modes for carrying out the invention, the invention is not limited to them and may be applied to reflection type liquid crystal displays. While MVA type liquid crystal displays have been referred to in the above-described modes for carrying out the invention, the invention is not limited to them and may be applied to liquid crystal displays in other modes such as the TN mode. 
     As thus described, the present invention makes it possible to provide a liquid crystal display having high luminance and preferable display characteristics.

Technology Classification (CPC): 6