JP3603974B2 - Wiring board and display device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring board provided with a two-terminal non-linear element having a laminated structure of metal-insulating film-metal and applied to, for example, a display device such as a liquid crystal display device and a method of manufacturing the same. The present invention relates to a wiring board in which an insulating film of a nonlinear element is formed by anodic oxidation of a lower metal, a method of manufacturing the same, and a display device using the wiring board.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, liquid crystal display devices have been widely used for various applications such as personal computers, word processors, terminal display devices for office automation, and televisions because of their low power consumption, light weight, and thinness. . In recent years, in particular, there has been a demand for a large display content and high image quality.
[0003]
As a conventional liquid crystal display device, a device using a simple matrix drive by a voltage averaging method of a TN (Twisted Nematic) method or an STN (Super Twisted Nematic) method is generally known. However, the above method is not suitable for large-capacity display because a sufficient contrast ratio cannot be obtained with an increase in the number of scanning lines.
[0004]
In view of this, an active drive system in which a switching element is provided for each pixel constituting a display screen has been conventionally developed. As the switching element in the active driving method, a thin film transistor or a two-terminal nonlinear element is used. In particular, a liquid crystal display device using a two-terminal nonlinear element having a simple structure is expected to be promising in terms of manufacturing cost. Above all, a so-called MIM (Metal-Insulator-Metal) type two-terminal nonlinear element having a laminated structure of metal-insulating film-metal has already been put to practical use.
[0005]
Note that a method of forming the insulating film by an anodic oxidation method is conventionally known. The formation of an insulating film by the anodic oxidation method has advantages such as the ability to form a uniform film over a large area and a relatively high throughput as compared with other thin film forming techniques such as sputtering, vacuum deposition, or CVD. is there.
[0006]
For example, Japanese Patent Application Laid-Open No. 55-161273 discloses a technique of forming tantalum pentoxide by anodizing Ta as an insulating film. As the insulating film in the MIM-type two-terminal nonlinear element that is currently in practical use, the one made of tantalum pentoxide is mainly used. In addition, Al or the like also exists as a metal that can be anodized in addition to Ta. However, in consideration of the non-linearity and symmetry of the device characteristics after formation, Ta is generally used conventionally. .
[0007]
Here, an example of a conventional method of manufacturing a wiring board using a two-terminal nonlinear element as a switching element will be described with reference to FIGS.
[0008]
FIGS. 11A, 11C, 11E, and 11G are plan views showing the configuration of a conventional wiring board in the order of main manufacturing steps. Each of FIGS. 11B, 11D, 11F, and 11H is a cross-sectional view showing a cross section taken along a plane along the line EE shown in each of the plan views. .
[0009]
First, a base coat insulating film (not shown) is formed on the glass substrate 60. Next, after a Ta film is formed on the base coat insulating film by a sputtering method, the Ta film is patterned by a photolithography method to form a signal wiring 62 and a branch line (lower electrode) 61 of the signal wiring 62. Are simultaneously formed.
[0010]
Next, the surfaces of the signal wiring 62 and the lower electrode 61 are anodized to form insulating films 62a and 61a, respectively, thereby obtaining an insulating film of a two-terminal nonlinear element.
[0011]
When a plurality of cells (wiring boards) are simultaneously formed in a mass production line or the like, a plurality of cells 75 are arranged on one large substrate 76 as shown in FIG. Are connected to each other to form an anodic oxide wiring 77. That is, the substrate 76 is immersed in an electrolytic solution bath, and a formation voltage is applied to the anodic oxidation wiring 77, whereby anodization is simultaneously performed on all of the plurality of cells 75. At this time, as shown in FIG. 13, the input terminals 78 connected to the external circuit after completion in each cell 75 are covered with a protective film 79 such as a resist so as not to be anodized.
[0012]
Subsequently, as described above, a metal film such as Al, Cr, or Ti is formed by sputtering so as to cover the insulating film 61a formed by anodic oxidation, and then patterned by photolithography. Thereby, the upper electrode 63 of the two-terminal nonlinear element is formed.
[0013]
Finally, after forming a thin film of a transparent conductive film such as ITO on the entire surface, patterning is performed by a photolithography method to form a pixel electrode 64, as shown in FIG. Is completed. This wiring board can be applied to a liquid crystal display device or the like.
[0014]
Hereinafter, the wiring substrate including the two-terminal nonlinear element as described above is referred to as an element-side substrate, and a method of manufacturing a liquid crystal display device using the element-side substrate will be described.
[0015]
FIG. 15 is a cross-sectional view schematically showing a configuration of a liquid crystal display device formed using the above-described element-side substrate. FIG. 15 is a cross-sectional view showing a cross section when the liquid crystal display device is cut along a plane corresponding to line FF in FIG.
[0016]
The substrate that sandwiches the liquid crystal in pair with the element-side substrate (hereinafter, referred to as the opposite-side substrate) is manufactured as follows. First, a base coat insulating film (not shown) is formed on the glass substrate 69 (not shown). Next, the opposing electrode 68 is formed by patterning a transparent conductive film made of ITO or the like into a stripe shape. Further, a color filter layer or the like may be formed as necessary.
[0017]
Further, alignment films 66a and 66b are respectively formed on the surfaces of the above-mentioned element-side substrate and the opposite-side substrate. These alignment films 66a and 66b are made of an organic resin and fired at 200 ° C. Further, as schematically shown in FIG. 15, the alignment films 66a and 66b are rubbed so that the twist angle of the liquid crystal molecules 67a in the liquid crystal 67 is 90 °.
[0018]
When the element-side substrate and the opposing-side substrate are bonded to each other, first, a thermosetting sealing agent is applied to one substrate, and spacers are dispersed on the other substrate. Then, the signal wiring 62 of the element-side substrate and the opposing electrode 68 of the opposing-side substrate are opposed to each other so as to be orthogonal to each other, and both substrates are bonded to each other, and then heat-pressed. Thereafter, a liquid crystal 67 is injected into a gap between the two substrates and sealed. Thus, a liquid crystal cell is completed.
[0019]
By disposing the transmission type polarizing plates 70a and 70b respectively on the entire surface and the back surface of the liquid crystal cell, a transmission type liquid crystal display device is constituted. Note that a reflective liquid crystal display device can be obtained by employing a configuration in which a reflective plate is further provided on the rear polarizing plate 70a.
[0020]
By the way, in the above-mentioned conventional wiring board, the signal wiring and the lower electrode are formed of the same material (Ta), and the insulating film is formed by the anodic oxide film of the lower electrode. A non-linear element can be formed. Further, since the Ta oxide film is used as the insulating film, this two-terminal nonlinear element has nonlinear characteristics with good symmetry.
[0021]
[Problems to be solved by the invention]
However, the above conventional configuration has the following problem due to the fact that both the lower electrode 61 and the signal wiring 62 of the MIM type two-terminal nonlinear element are formed of Ta. That is, Ta is a material having a relatively high specific resistance as a metal. For this reason, there is a problem that signal attenuation or dulling occurs between the side closer to the input terminal of the signal wiring 62 and the side farther from the input terminal, causing phenomena such as gradation and crosstalk, and deteriorating the display quality of the display device.
[0022]
[Means for Solving the Problems]
In order to solve the above problem, a wiring board according to claim 1 is a wiring board comprising: a pixel electrode; a signal wiring; and a two-terminal nonlinear element connected to the signal wiring and the pixel electrode. Terminal nonlinear element,Made of Ta and partially overlapped with the signal wiring.A lower electrode connected thereto;The surface of the lower electrodeAn insulating film formed by anodic oxidation and an upper electrode made of metal and connected to the pixel electrode are sequentially laminated, and the signal wiring has a higher electrical resistance than the lower electrode of the two-terminal nonlinear element. Of low Al or an alloy containing Al as a main component,At the same time as the insulating film of the two-terminal nonlinear element, the surface of the signal wiring is covered with an Al oxide film obtained by anodic oxidation.It is characterized by:
[0023]
In the above configuration, since the signal wiring is formed from a metal having lower electric resistance than the lower electrode of the two-terminal nonlinear element, the wiring resistance can be reduced. This prevents the signal input to the signal wiring from being dulled by the wiring resistance. As a result, when this wiring board is applied to a display device, the occurrence of phenomena such as gradation and crosstalk is suppressed, and high-quality display can be realized.
[0024]
Further, since the signal wiring also functions as an anodic oxidation wiring, the wiring resistance at the time of anodic oxidation is reduced, so that the insulating film of the two-terminal nonlinear element is formed uniformly. Thus, it is possible to provide a wiring board that suppresses variation in element characteristics and realizes more uniform display in a display device.
[0025]
Further, since the signal wiring is formed of Al or an alloy containing Al as a main component, the wiring resistance is reduced, and it is possible to provide a wiring substrate that realizes a more uniform display in a display device.
[0026]
further,By forming the lower electrode from Ta, the insulating film is formed of tantalum pentoxide obtained by anodizing tantalum. As a result, a two-terminal nonlinear element having excellent symmetry of nonlinear characteristics is realized.
[0027]
Claim2The wiring substrate according to the present invention is a wiring substrate including a pixel electrode, a signal wiring, and a two-terminal nonlinear element connected to the signal wiring and the pixel electrode, wherein the two-terminal nonlinear element includes:TaAnd a lower electrode connected to the signal wiring, an insulating film formed by anodizing the lower electrode, and an upper electrode made of metal and connected to the pixel electrode. The signal wiring is made of a transparent and conductive material, and the lower electrode is formed so as to partially overlap the signal wiring.
[0028]
According to the above configuration, since the signal wiring is made of a transparent and conductive material, the aperture ratio is improved, and a bright display is realized in the display device using the wiring substrate. Further, since the signal wiring itself is not anodized, it is not necessary to form a protective film or the like in the input terminal portion for connecting the signal wiring to an external circuit in the anodizing step. As a result, the manufacturing process is simplified, and the manufacturing cost can be reduced.
[0029]
Further, by forming the lower electrode from Ta, the insulating film is formed of tantalum pentoxide obtained by anodizing tantalum. As a result, a two-terminal nonlinear element having excellent symmetry of nonlinear characteristics is realized.
[0030]
Claim3The wiring board described in the claim2In the configuration described,UpThe signal wiring is ITO, In_TwoO_Three, And SnO_TwoThe feature is that it consists of either.
[0031]
According to the above configuration, FaithNo. wiring is ITO, In_TwoO_ThreeOr SnO_TwoBy being formed from such a transparent and highly conductive material, it is possible to realize a high-quality display that is bright and free of gradation, crosstalk, and the like in a display device to which this wiring substrate is applied.
[0032]
Claim4The display device described in claims 1 to3A display element is sandwiched between the wiring substrate according to any one of the above and a counter substrate having a plurality of transparent conductive films formed substantially in parallel on the transparent substrate.
[0033]
For example, liquid crystal can be suitably used as the display element. According to the above configuration, it is possible to provide a display device that realizes bright and high-quality display.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS.
[0035]
1 (a), (c), (e), (g) and (i) are plan views showing the configuration of a wiring board according to an embodiment of the present invention in the order of main manufacturing steps. 1 (b), (d), (f), (h), and (j) are cross-sectional views each showing a cross section taken along a plane along line AA shown in each of the plan views. It is.
[0036]
The wiring board of the present embodiment includes a so-called MIM (Metal-Insulator-Metal) type two-terminal nonlinear element in which an insulating film is sandwiched between metal layers, and is manufactured by the following method. First, a 3000 ° thick base coat insulating film (not shown) made of tantalum pentoxide or the like is formed on a glass substrate 10 by a direct current (DC) sputtering method or the like. As the glass substrate 10, for example, Fusion Pyrex glass having a trade name of “7059” manufactured by Corning Incorporated can be used. However, the present invention is not limited to this, and a glass substrate made of, for example, quartz glass, borosilicate glass, soda lime glass, or the like can be used.
[0037]
Although the base coat insulating film can be omitted, the formation of the base coat insulating film prevents other thin films formed on the base coat insulating film from being contaminated by impurities contained in the glass substrate 10. Therefore, there is an effect that the characteristics of the two-terminal nonlinear element are improved.
[0038]
Next, a Ta thin film is formed on the glass substrate 10 to a thickness of 3000 ° by a DC sputtering method. Here, a sintered body target having a nitrogen concentration of 2 to 10 mol% is used, a reaction gas is argon at a flow rate of 100 sccm, a sputtering gas pressure is 0.4 Pa, and a DC power is 2.6 W / cm.^TwoThe substrate was heated at a temperature of 100 ° C. for 3 minutes, the substrate was conveyed at a speed of 100 mm / min, and the distance between the substrate and the target was 77 mm. Further, CF is applied to the Ta thin film._FourAnd O_Two1A and 1B, an island-shaped lower electrode 11 is formed on the surface of the glass substrate 10 as shown in FIGS.
[0039]
Next, an Al thin film is formed to a thickness of 4000 ° by a sputtering method. The Al thin film may be formed from an alloy containing Al as a main component. Then, the Al thin film is formed, for example, by using HF and HNO._ThreeBy patterning into a line shape as shown in FIGS. 1C and 1D by a photolithography method using an air-fuel mixture as an etchant, the signal wiring 12 is formed so as to cover a part of the lower electrode 11. Form. Note that the signal wiring 12 also functions as an anodic oxidation wiring in an anodic oxidation step described later.
[0040]
Next, using a 1% ammonium tartrate solution as an electrolytic solution, the surface of the lower electrode 11 and the surface of the signal wiring 12 excluding the vicinity of the connection terminal to the external drive circuit are anodized. Thus, as shown in FIGS. 1E and 1F, an insulating film 11a made of tantalum pentoxide having a thickness of about 600 ° is formed on the surface of the lower electrode 11 and the Al oxide is formed on the surface of the signal wiring 12. The insulating film 12a made of is formed. In this case, the anodic oxidation was performed at a liquid temperature of about 25 ° C., a formation voltage of 31 V, and a formation current of about 10 mA / sheet.
[0041]
Next, a Ti thin film having a thickness of, for example, 4000 ° is formed by a sputtering method, and the Ti thin film is patterned by a photolithography method using, for example, 5% HF as an etchant. Thus, upper electrode 13 is formed such that anodic oxide film 11a and a part thereof overlap. Here, although Ti is used as the material of the upper electrode 13, Ta, Cr, Al, or the like can be used instead.
[0042]
Finally, by laminating and patterning a transparent conductive film made of ITO or the like, a pixel electrode 14 is formed so as to cover a part of the upper electrode 13 as shown in FIGS. 1 (i) and 1 (j). . Through the above steps, as shown in FIG. 2, a wiring board having a two-terminal nonlinear element is completed.
[0043]
According to the above configuration, the two-terminal nonlinear element is composed of Ta / Ta_TwoO_Five/ Ti MIM structure. In other words, this two-terminal nonlinear element has nonlinear characteristics with good symmetry because the insulating layer is formed of an anodic oxide film of Ta. Further, since the signal wiring 12 is formed of Al or an alloy containing Al as a main component, the wiring resistance is lower than that of a conventional case using Ta as a wiring material. Accordingly, when a display device such as a liquid crystal display device is formed using this wiring substrate, display unevenness, crosstalk, gradation, and the like due to signal dulling due to wiring resistance are reduced, and uniform high-quality display can be performed. Become.
[0044]
Further, since the signal wiring 12 also serves as an anodic oxidation wiring, the wiring resistance at the time of anodic oxidation is reduced, and the thickness of the insulating film (insulating film 11a) of the MIM type two-terminal nonlinear element must be uniform. Can be. As a result, variations in element characteristics are suppressed, and more uniform display can be realized.
[0045]
[Embodiment 2]
Another embodiment according to the present invention will be described below with reference to FIGS.
[0046]
3A, 3C, 3E, and 3G are plan views showing the configuration of the switching element according to the present embodiment in the order of main manufacturing steps. FIGS. 3B, 3D, 3F, and 3H are cross-sectional views each showing a cross section taken along a plane along line BB shown in each of the plan views. .
[0047]
The wiring board of the present embodiment is manufactured by the following method. First, as in the first embodiment, a base coat insulating film is formed on a glass substrate 20. The base coat insulating film is not essential and may be omitted.
[0048]
Next, a Ta thin film is formed to a thickness of 3000 ° by DC sputtering. Then, this Ta thin film is_FourAnd O_Two3A and 3B, an island-shaped lower electrode 21 is formed. At the time of this patterning, a terminal portion (see an input terminal 25 in FIG. 5) for connecting an external circuit to the wiring board is formed simultaneously with the lower electrode 21.
[0049]
Next, a transparent conductive film made of a transparent and highly conductive material such as ITO is formed to a thickness of 2500 ° by sputtering to cover the glass substrate 20 on which the lower electrode 21 is formed. This transparent conductive film is made of, for example, HF and HNO_ThreeAs shown in FIGS. 3C and 3D, the signal wiring 22 and the pixel electrode 24 are simultaneously formed by patterning by a photolithography method using an air-fuel mixture as an etchant. Here, an example in which ITO is used as the material of the transparent conductive film has been described._TwoO_ThreeOr SnO_TwoEtc. can be suitably used.
[0050]
Next, by anodizing the surface of the lower electrode 21 using a 1% ammonium tartrate solution as an electrolyte, as shown in FIGS. 3E and 3F, the surface is exposed without being covered with the signal wiring 22. An insulating film 21a is formed on the surface of the lower electrode 21 which is formed. Here, anodization was performed at an electrolyte temperature of about 25 ° C., a formation voltage of 31 V, a formation current of about 10 mA / sheet, and an insulating film 21a made of tantalum pentoxide having a thickness of about 600 ° was obtained.
[0051]
Next, a Ti thin film having a thickness of, for example, 4000 .ANG. Is formed by sputtering, and the Ti thin film is patterned by, for example, a photolithography method using EDTA as an etchant, thereby forming an anode, as shown in FIGS. The upper electrode 23 is formed so as to partially overlap with each of the oxide film 21a and the pixel electrode 24. Here, Ti is used as the material of the upper electrode 23, but Ta, Cr, Al, or the like can be used instead.
[0052]
Through the above steps, as shown in FIG. 4, the lower electrode 21 (Ta) and the insulating film 21a (Ta_TwoO_Five) And a two-terminal nonlinear element composed of the upper electrode 23 (Ti), a transparent signal wiring 22, and a pixel electrode 24 are completed.
[0053]
In the above configuration, the lower electrode 21 is formed of Ta, and the insulating film 21a is formed of tantalum pentoxide obtained by anodizing the lower electrode 21. A non-linear element is realized.
[0054]
Further, since the signal wiring 22 is formed of a transparent and highly conductive material, the aperture ratio is improved. Thus, when a display device is formed using this wiring substrate, bright and high-quality display can be performed on the display device. Further, since it is not necessary to form a thin wiring in order to improve an aperture ratio as in the conventional case, it is possible to form a thick wiring to reduce a wiring resistance value, and to achieve higher quality display in a display device. Can be realized.
[0055]
Further, in the above configuration, as shown in FIG. 5, the input terminals 25 for connecting an external circuit are covered with a transparent conductive film realized by ITO or the like. The input terminals 25 need not be protected with a protective film or the like as in the conventional case. As a result, the manufacturing process can be simplified, and the manufacturing cost can be reduced. Incidentally, reference numeral 26 shown in FIG. 5 denotes an anodized wiring.
[0056]
[Embodiment 3]
Another embodiment according to the present invention will be described below with reference to FIGS.
[0057]
6A, 6C, 6E, and 6G are plan views showing the configuration of the switching element according to the present embodiment in the order of main manufacturing steps. 6 (b), (d), (f), and (h) are cross-sectional views each showing a cross section taken along a plane along the line CC shown in each of the plan views. .
[0058]
The wiring board according to the present embodiment is different from the wiring board according to the second embodiment mainly in that the manufacturing process of the lower electrode of the two-terminal nonlinear element is performed after the manufacturing process of the signal wiring and the pixel electrode. Are different.
[0059]
The method for manufacturing the wiring board of the present embodiment is as follows. First, a base coat insulating film is formed on a glass substrate 30 as in the first embodiment. The base coat insulating film is not essential and may be omitted.
[0060]
Next, a transparent conductive film made of, for example, ITO is formed to a thickness of 2500 ° on the surface of the glass substrate 30 by a sputtering method. Then, the transparent conductive film is formed by, for example, HF and HNO._ThreeAs shown in FIGS. 6A and 6B, the signal wiring 32 and the pixel electrode 34 are formed by patterning by a photolithography method using an air-fuel mixture as an etchant.
[0061]
Next, on the glass substrate 30 on which the signal wiring 32 and the pixel electrode 34 are formed, a Ta thin film is formed to a thickness of 3000 ° by DC sputtering. Then, this Ta thin film is_FourAnd O_Two6C and 6D, an island-shaped lower electrode 31 is formed by patterning by dry etching using an air-fuel mixture. The lower electrode 31 is formed so as to partially overlap the signal wiring 32 and not to overlap with the pixel electrode 34.
[0062]
Next, the surface of the lower electrode 31 is anodized using a 1% ammonium tartrate solution as an electrolytic solution, thereby forming an insulating film 31a on the surface of the lower electrode 31, as shown in FIGS. Form. Here, anodic oxidation was performed at an electrolyte temperature of about 25 ° C., a formation voltage of 31 V, and a formation current of about 10 mA / sheet to obtain an insulating film 31a made of tantalum pentoxide having a thickness of about 600 °.
[0063]
Next, a Ti thin film having a thickness of, for example, 4000 .ANG. Is formed by sputtering, and the Ti thin film is patterned by, for example, a photolithography method using EDTA as an etchant, thereby forming an anode as shown in FIGS. 6 (g) and 6 (h). The upper electrode 33 is formed so as to partially overlap with each of the oxide film 31a and the pixel electrode 34. Here, Ti is used as the material of the upper electrode 33, but Ta, Cr, Al, or the like can be used instead.
[0064]
Through the above steps, as shown in FIG. 7, the lower electrode 31 (Ta) and the insulating film 31a (Ta_TwoO_Five) And a two-terminal nonlinear element composed of the upper electrode 33 (Ti), the transparent signal wiring 32, and the pixel electrode 34 are completed.
[0065]
In the above configuration, the lower electrode 31 is formed of Ta, and the insulating film 31a is formed of tantalum pentoxide obtained by anodizing the lower electrode 31. A non-linear element is realized.
[0066]
Further, since the signal wiring 32 is formed of a transparent and highly conductive material, the aperture ratio is improved. Thus, when a display device is formed using this wiring substrate, bright and high-quality display can be performed on the display device.
[0067]
Further, also in the configuration of the present embodiment, in the anodic oxidation step, it is not necessary to protect the input terminal for connecting the present wiring board to an external circuit with a protective film or the like, so that the manufacturing process can be simplified. In addition, the manufacturing cost can be reduced.
[0068]
[Embodiment 4]
Still another embodiment according to the present invention will be described below with reference to FIGS. 8 and 9.
[0069]
8A, 8C, 8E, 8G, 8I, 8K, and 8M show the configuration of the switching element according to the present embodiment in the order of main manufacturing steps. It is a top view. Also, each of FIGS. 8B, 8D, 8F, 8H, 8J, 8L, and 8N is cut along the DD line shown in each of the plan views. FIG.
[0070]
The wiring board of the present embodiment is manufactured by the following method. First, as in the first embodiment, a base coat insulating film is formed on a glass substrate 40. The base coat insulating film is not essential and may be omitted.
[0071]
Next, a transparent conductive film made of a transparent and highly conductive material such as ITO is formed on the surface of the glass substrate 40 so as to have a thickness of 2500 ° by a sputtering method. Then, the transparent conductive film is formed by, for example, HF and HNO._ThreeAs shown in FIGS. 8A and 8B, a linear signal wiring 42 is formed by patterning by a photolithography method using an air-fuel mixture as an etchant.
[0072]
Further, a Ta thin film is formed to a thickness of 3000 ° on the glass substrate 40 on which the signal wiring 42 is formed by a DC sputtering method. Then, this Ta thin film is_FourAnd O_TwoAs shown in FIGS. 8C and 8D, an island-shaped lower electrode 41 is formed on the signal wiring 42 by dry etching with a mixture of the above.
[0073]
Next, the surface of the lower electrode 41 is anodized using a 1% ammonium tartrate solution as an electrolytic solution, thereby forming an insulating film 41a on the surface of the lower electrode 41 as shown in FIGS. 8 (e) and 8 (f). Form. Here, anodization was performed at an electrolyte temperature of about 25 ° C., a formation voltage of 31 V, and a formation current of about 10 mA / sheet to obtain an insulating film 41a made of tantalum pentoxide having a thickness of about 600 °.
[0074]
Next, as shown in FIGS. 8 (g) and 8 (h), an island-shaped lower electrode 41 and an insulating film formed on the surface thereof are formed by forming a Ti thin film having a thickness of, for example, 4000 ° by sputtering and patterning the Ti thin film, as shown in FIGS. The upper electrode 43 is formed so as to cover all the portions 41 a and not to protrude from the signal wiring 42.
[0075]
Next, a photosensitive resin is applied so as to have a thickness of about 2.5 μm by spin coating at a rotation speed of 500 to 3000 rpm, and as shown in FIGS. A film 45 is formed.
[0076]
Next, the organic insulating film 45 is pre-baked at about 90 ° C. and subjected to a photolithography process, so as to expose a part of the upper electrode 43 as shown in FIGS. To form
[0077]
Finally, as shown in FIGS. 8 (m) and 8 (n), the pixel electrode 44 is covered with Al so as to cover the surface of the organic insulating film 45 and to be connected to the upper electrode 43 in the contact hole 46. To form Note that this pixel electrode 44 functions as a reflective electrode that reflects light.
[0078]
Through the above steps, as shown in FIG. 9, the lower electrode 41 (Ta) and the insulating film 41a (Ta_TwoO_Five) And a two-terminal non-linear element composed of the upper electrode 43 (Ti) and a reflective pixel electrode 44 are completed.
[0079]
In the above configuration, the lower electrode 41 is formed of Ta, and the insulating film 41a is formed of tantalum pentoxide obtained by anodizing the lower electrode 41. A non-linear element is realized.
[0080]
Furthermore, since the pixel electrode 44 functions as a reflective electrode that reflects light, a reflective display device that does not require a backlight can be realized by using this wiring substrate. In addition, when a reflection type display device is realized using the above-described wiring board, since a reflection electrode is formed in the wiring board, a reflection plate is formed outside the wiring board. A double image due to a display image and a shadow can be eliminated, and higher-quality display can be performed.
[0081]
In the above-described wiring board of the present embodiment, the upper electrode 43 may be omitted, and the pixel electrode 44 may be directly connected to the insulating film 41a. According to this configuration, the step of forming and patterning Ti or the like to form the upper electrode 43 can be omitted, so that the manufacturing process can be simplified.
[0082]
[Embodiment 5]
Another embodiment according to the present invention will be described below with reference to FIG.
[0083]
The wiring boards described in each of Embodiments 1 to 4 can be suitably used for a display device such as a liquid crystal display device. Hereinafter, a wiring substrate having a two-terminal nonlinear element, such as the above-described wiring substrate, is referred to as an element-side substrate, and a liquid crystal display device including the element-side substrate will be described.
[0084]
FIG. 10 is a cross-sectional view schematically illustrating a configuration of a liquid crystal display device formed using the wiring substrate described in Embodiment 1 as an element-side substrate. The substrate that sandwiches the liquid crystal in pair with the element-side substrate (hereinafter, referred to as the opposite-side substrate) is manufactured as follows. First, a base coat insulating film (not shown) is formed on the glass substrate 59 (not shown). Next, the opposing electrode 58 is formed by patterning a transparent conductive film made of ITO or the like into a stripe shape. Further, a color filter layer or the like may be formed as necessary.
[0085]
In addition, alignment films 51a and 51b are respectively formed on the surfaces of the above-described element-side substrate and the counter-side substrate. These alignment films 51a and 51b are realized by, for example, an organic resin fired at 200 ° C., but are not limited thereto. Further, as schematically shown in FIG. 10, the alignment films 51a and 51b are subjected to rubbing treatment so that the twist angle of the liquid crystal molecules 57a in the liquid crystal 57 is 90 °.
[0086]
When the element-side substrate and the opposing-side substrate are bonded to each other, first, a thermosetting sealing agent is applied to one substrate, and spacers are dispersed on the other substrate. Then, the signal wiring 12 of the element-side substrate and the opposing electrode 58 of the opposing substrate are opposed to each other so as to be orthogonal to each other, and both substrates are bonded to each other, and then heat-pressed. Thereafter, a liquid crystal 57 (display element) is injected into a gap between the two substrates and sealed. Thus, a liquid crystal cell is completed. By disposing the transmission type polarizing plates 50a and 50b respectively on the entire surface and the back surface of the liquid crystal cell, a transmission type liquid crystal display device is constituted.
[0087]
In the above, the transmission type liquid crystal display device including the wiring substrate described in Embodiment 1 has been described. However, the same applies to the case where the wiring substrate described in Embodiments 2 and 3 is used as an element-side substrate. Thus, a transmission type liquid crystal display device can be configured.
[0088]
Note that the wiring substrate described in Embodiment 4 has a reflective pixel electrode formed of Al or the like, and a reflective liquid crystal display device can be realized by using this wiring substrate. In this case, it is not necessary to provide a reflecting plate on the rear polarizing plate 50a side. That is, in the reflection type liquid crystal display device, since the reflection electrode is formed in the wiring board, a problem of a double image due to a display image and a shadow generated when the reflection plate is formed outside the wiring board is eliminated. This has the effect that high-quality display can be realized.
[0089]
【The invention's effect】
As described above, in the wiring board according to claim 1, the two-terminal nonlinear element includes:Made of Ta Some overlap with signal wiringA lower electrode connected thereto;The surface of the lower electrodeAn insulating film formed by anodization and an upper electrode made of metal and connected to the pixel electrode are sequentially laminated, and the signal wiring has an electric resistance lower than that of the lower electrode of the two-terminal nonlinear element. Made of low Al or an alloy mainly containing Al,At the same time as the insulating film of the two-terminal nonlinear element, the surface of the signal wiring is covered with an Al oxide film obtained by anodic oxidation.Configuration.
[0090]
This suppresses the dulling of the signal input to the signal wiring due to the wiring resistance, so that when this wiring board is applied to a display device, the occurrence of phenomena such as gradation and crosstalk is suppressed, and high-quality display is achieved. This has the effect that it can be realized. Further, since the signal wiring also functions as an anodic oxidation wiring, the thickness of the insulating film of the two-terminal nonlinear element is formed uniformly. Thus, there is an effect that it is possible to suppress a variation in element characteristics and to provide a wiring board that realizes more uniform display in a display device.
[0091]
Further, since the signal wiring is formed of Al or an alloy containing Al as a main component, the wiring resistance is reduced, and it is possible to provide a wiring substrate that realizes a more uniform display in a display device.
[0092]
Further, by the configuration in which the lower electrode is made of Ta,This has the effect of realizing a two-terminal nonlinear element having excellent symmetry of the nonlinear characteristic and providing a wiring board that realizes a more uniform display in the display device.
[0093]
Claim2The described wiring board has a two-terminal nonlinear element,TaAnd a lower electrode connected to the signal wiring, an insulating film formed by anodizing the lower electrode, and an upper electrode made of metal and connected to the pixel electrode. The signal wiring is made of a transparent and conductive material, and the lower electrode is formed so as to partially overlap the signal wiring.
[0094]
As a result, the aperture ratio is improved, and an effect that a bright display can be realized in a display device to which this wiring board is applied is achieved. Further, since the signal wiring itself is not anodized, it is not necessary to form a protective film or the like in the input terminal portion for connecting the signal wiring to an external circuit in the anodizing step. As a result, there is an effect that the manufacturing process is simplified and the manufacturing cost can be reduced.
[0095]
Further, a two-terminal nonlinear element having excellent non-linear characteristic symmetry is realized by the configuration in which the lower electrode is made of Ta.
[0096]
Claim3The wiring board described in the claim2In the configuration described,UpThe signal wiring is ITO, In_TwoO_Three, And SnO_TwoIt is a structure which consists of either.
[0097]
This, FaithSince the signal wiring is formed from a transparent and highly conductive material, a display device using the wiring substrate has an effect that a bright, high-quality display can be realized.
[0098]
Claim4The display device described in claims 1 to3The display element is sandwiched between the wiring substrate according to any one of the above and a counter substrate having a plurality of transparent conductive films formed substantially in parallel on the transparent substrate.
[0099]
Thereby, there is an effect that a display element realizing high-quality display can be provided.
[Brief description of the drawings]
FIGS. 1 (a), (c), (e), (g), and (i) are plan views showing the configuration of a wiring board according to an embodiment of the present invention in the order of main manufacturing steps. FIG. 1 (b), (d), (f), (h), and (j) are cross-sectional views taken along the line AA shown in each of the plan views.
FIG. 2 is a plan view showing a configuration of the wiring substrate by cutting out a part of an insulating film formed on a surface of each of a signal wiring and a lower electrode.
FIGS. 3 (a), (c), (e), and (g) are plan views showing a configuration of a wiring board as another embodiment according to the embodiment of the present invention in the order of main manufacturing steps. is there. 3 (b), (d), (f), and (h) are cross-sectional views taken along the line BB shown in the plan views.
FIG. 4 is a plan view showing the configuration of the wiring board with a part of an insulating film formed on the surface of a lower electrode being cut away.
FIG. 5 is a plan view showing a configuration of the wiring board in a step of performing anodic oxidation when manufacturing the wiring board.
FIGS. 6A, 6C, 6E, and 6G are plan views showing the configuration of a wiring board according to still another embodiment of the present invention in the order of main manufacturing steps. It is. 6 (b), (d), (f), and (h) are cross-sectional views taken along the line CC shown in the plan views.
FIG. 7 is a plan view showing the configuration of the wiring substrate with a part of an insulating film formed on the surface of a lower electrode being cut away.
FIGS. 8 (a), (c), (e), (g), (i), (k), and (m) show a wiring board according to still another embodiment of the present invention. FIG. 3 is a plan view showing the configuration of the first embodiment in the order of main manufacturing steps. 8 (b), (d), (f), (h), (j), (l), and (n) are cut planes along the line DD shown in each of the plan views. FIG.
FIG. 9 is a plan view showing the configuration of the wiring substrate with a part of an insulating film formed on the surface of a lower electrode cut away.
FIG. 10 is a cross-sectional view schematically illustrating a configuration of a liquid crystal display device according to an embodiment of the invention.
FIGS. 11A, 11C, 11E, and 11G are plan views showing the configuration of a conventional wiring board in the order of main manufacturing steps. 11B, 11D, 11F, and 11H are cross-sectional views taken along the line EE shown in the plan views.
FIG. 12 shows a case where a plurality of wiring boards are arranged on a large board when an existing wiring board is manufactured on a mass production line, and anodized wiring is formed on the large board so that these wiring boards are connected to each other. It is a top view showing a situation.
FIG. 13 is a plan view showing a state in which a protective film is provided on an input terminal portion of a signal wiring when performing anodic oxidation in a conventional wiring board manufacturing process.
FIG. 14 is a plan view showing a configuration of the conventional wiring board by cutting out a part of an insulating film formed on a surface of a signal wiring and a lower electrode.
FIG. 15 is a cross-sectional view schematically illustrating an example of a configuration of a liquid crystal display device formed using a conventional wiring substrate.
[Explanation of symbols]
11 Lower electrode
11a insulating film
12 signal wiring
13 Upper electrode
14 Pixel electrode
57 liquid crystal (display element)

Claims (4)

A pixel electrode, a signal wiring, and a wiring substrate including a two-terminal nonlinear element connected to the signal wiring and the pixel electrode;
The two-terminal nonlinear element, and a lower electrode connected to overlap the signal line and a part with consisting Ta, an insulating film formed by a surface of the lower electrode is anodized, the pixel electrode with made of metal And the connected upper electrode are sequentially laminated,
The signal wiring is made of Al or an alloy containing Al as a main component having lower electric resistance than the lower electrode of the two-terminal nonlinear element, and anodizes the surface of the signal wiring simultaneously with the insulating film of the two-terminal nonlinear element. A wiring board covered with an Al oxide film obtained by the above method. A pixel electrode, a signal wiring, and a wiring substrate including a two-terminal nonlinear element connected to the signal wiring and the pixel electrode;
A lower electrode formed of Ta and connected to the signal wiring, an insulating film formed by anodizing the lower electrode, and an upper electrode formed of metal and connected to the pixel electrode; And are sequentially laminated,
The signal wiring is made of a transparent and conductive material,
The wiring board, wherein the lower electrode is formed so as to partially overlap the signal wiring. The signal wiring is ITO, In _Two O _Three , And SnO _Two 3. The wiring board according to claim 2, comprising: A display element is sandwiched between the wiring substrate according to any one of claims 1 to 3 and an opposing substrate having a plurality of transparent conductive films formed substantially in parallel on a transparent substrate. Display device.

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