JPH1020345A - Wiring board having two-terminal switching element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the damage of the lower layer wirings of signal wirings at the time of an etching treatment. SOLUTION: Electrodes 73 of respective columns among pixel electrodes 73 arranged in a matrix form are respectively connected via MIM(metal insulator metal) to the respective signal wirings 74 of a substrate member 6 of the liquid crystal panel of a liquid crystal display device. The opening rate of the member 67 is higher than the opening rate of the substrate member formed by using TFTs(thin-film transistors). The execution of a brighter display with the liquid crystal display device of a reflection type is possible. The signal wirings 74 have a laminated structure to cover the wirings 79 by superposing the upper layer wirings 78 cpnsisting of tantalum on lower layer wirings 79 consisting of a mixed material contg. aluminum. The specific resistance value of the mixed material is smaller than the specific resistance value of the tantalum. The wiring resistance value over the entire part of the signal wirings 74 is, therefore, lower than that when the signal wirings are formed of the tantalum alone. Further, the change in the shapes of the wirings in consequence of electromigration is prevented and, therefore, the damage of the lower layer wirings 9 at the time of the production stage is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board having a two-terminal switching element suitably used for a display device using an active matrix driving method.

[0002]

2. Description of the Related Art A liquid crystal display device is used as a display device for various electronic devices because of its low power consumption, thinness and light weight. For example, a liquid crystal display device is used as a display device of a personal computer and a word processor. It is also used as a terminal display device for office automation and a television display device. In recent years, in this liquid crystal display device, higher image quality of a displayed image and an increase in display capacity have been demanded.

A liquid crystal display device used as a display device of the above-described device performs a so-called matrix type display. 2. Description of the Related Art A liquid crystal display device that performs matrix display includes a plurality of pixels arranged in a matrix on a display screen that displays a display image. In this apparatus, the display state of each pixel is individually switched to display a display image as an arbitrary figure. In order to increase the display capacity in the device, the number of pixels forming the display screen is increased.

As such a liquid crystal display device, there is a simple matrix drive type liquid crystal display device using a voltage averaging method. The liquid crystal display device of the driving system has a configuration in which a liquid crystal layer is sandwiched between a pair of substrate members formed on one surface thereof in parallel with a plurality of strip-shaped display electrodes at predetermined intervals. The substrate member is disposed such that one surface on which the display electrodes are formed is opposed to each other, and the strip-shaped display electrodes are orthogonal to each other. Pixels of the liquid crystal display device are formed at portions where display electrodes of the respective substrate members overlap when the device is viewed from the normal direction of one surface of the substrate member.

In order to increase the display capacity in a simple matrix drive type liquid crystal display device, it is necessary to increase the number of strip-shaped display electrodes. When the number of display electrodes is increased with respect to a displayable region having a limited area, the width of each display electrode is reduced. As a result, the electric signal transmitted through the display electrode may be distorted, or the signal may leak to pixels other than the pixel to which the signal is to be applied. Therefore, the display contrast ratio in the device is reduced, and a desired contrast ratio cannot be obtained. As described above, the device of the simple matrix drive system is not suitable for large-capacity display having an extremely large number of pixels.

[0006] An active matrix driving method is known as a driving method of a liquid crystal display device of a matrix type display capable of performing a large capacity display. In an active matrix driving type liquid crystal display device, a switching element is provided for each pixel arranged in a matrix, and the pixel and a signal wiring for transmitting a signal are connected via the switching element, and the signal is individually transmitted to the pixel. Supply / cut off. As the switching element, for example, a thin film transistor (Thin Film Transistor; hereinafter, abbreviated to “TFT”) as a three-terminal element, and a metal-insulator-metal (Metal-Insulator-Metal; MIM ”). The driving method is a twisted nematic (hereinafter abbreviated as “TN”) type, a super twisted nematic (Su
per Twisted Nematic; hereinafter abbreviated as “STN”
And a guest-host (hereinafter abbreviated as "GH") type liquid crystal display device.

[0007] These active matrix drive type liquid crystal display devices are used, for example, in portable information terminal equipment. In this device, there is a demand for a liquid crystal display device capable of performing large-capacity display with high resolution. In this device, in order to increase the resolution and the display capacity, it is necessary to increase the number of pixels and to reduce the pixel interval as compared with a conventional liquid crystal display device. For this purpose, it is necessary to increase the length of the signal wiring and reduce the width thereof. Further, the number of pixels connected to a single signal line via a switching element increases.

When the width of the signal wiring is reduced, the wiring resistance generally increases, and the electric signal applied to the signal wiring becomes
As the distance from one end of the wiring, which is the signal input end, increases, the signal is attenuated and distorted. In addition, tantalum (Ta) is often used for signal wiring. Tantalum has a higher specific resistance value than other wiring materials. Therefore, when the length of the signal wiring is increased, the applied electric signal is attenuated as the distance from the electric signal input end of the signal wiring increases. Therefore, although an electric signal without attenuation is given to a pixel connected near the signal input end of the signal wiring, an attenuated electric signal is given to a pixel connected at a position distant from the input end.

Therefore, pixels in the vicinity of the signal input end of the signal wiring have a sufficient ON / OFF ratio of the electric signal and a high contrast ratio between white display and black display.
In a pixel connected at a position far from the input end, the contrast ratio is reduced. As a result, in a column of pixels connected to the same signal wiring, gradation occurs in which the contrast ratio decreases from a pixel closer to the electric signal input terminal to a pixel farther from the electric signal input terminal. Such gradation results in uneven lighting of the display of the display device.

As a first prior art for solving such a problem, there is a liquid crystal display device in which signal wirings have a laminated structure made of different conductive materials. The structure of a TN reflective liquid crystal display device using the active matrix driving method will be described below. The device has a so-called XGA pixel array. Each pixel individually takes one of the display states of white display and black display, and performs monochrome display as the entire display device.

In the liquid crystal display device, a pair of polarizing plates are provided with a liquid crystal panel interposed therebetween. The transmission axis of each polarizing plate is
Mutually orthogonal. A reflection plate is provided on one of the pair of polarizing plates on the side opposite to the liquid crystal panel. The liquid crystal panel has a configuration in which a TN liquid crystal layer is sandwiched between a pair of substrate members.

On the other hand, the substrate member is a substrate member on the reflector side of the pair of substrate members. In this one substrate member, the same number of pixel electrodes as the pixels of the liquid crystal display device are arranged on one surface on the liquid crystal layer side of an insulating glass substrate having translucency along horizontal and vertical directions H and V orthogonal to each other. They are arranged in a matrix. Thereafter, 1 is arranged linearly along the horizontal direction X.
The members of the group are called "rows". A group of components arranged linearly along the vertical direction Y is referred to as a “column”. The substrate is provided with a signal wiring for transmitting a signal to the pixel electrode, and a switching element for individually connecting the pixel wiring and the signal wiring. The electric signal transmitted through the signal wiring is individually supplied or cut off to each pixel electrode via the switching element.

FIG. 13 shows a MIM as a switching element.
FIG. 3 is a partial plan view showing a configuration for one pixel of one substrate member 1 using an element. On the other hand, the substrate member 1 includes the substrate 3, the pixel electrode 5, the signal wiring 6, and the MIM element 7.

The same number of pixel electrodes 5 as pixels are arranged in a matrix along the horizontal and vertical directions H and V on one surface of the substrate 3 on the liquid crystal layer side. The same number of signal lines 6 as the number of rows or columns of pixels are prepared, and the signal lines 6 are interposed between the rows or columns of the adjacent pixel electrodes 5 and arranged in parallel with each other. The pixel electrode 5 and the signal wiring 6 are electrically connected only via the MIM element 7. On one surface of the substrate 3, an alignment film (not shown) is formed so as to cover the pixel electrode 5, the signal wiring 6, and the MIM element 7.

FIG. 14 shows a TFT as a switching element.
FIG. 9 is a partial plan view showing a configuration of one pixel of a one-sided substrate member 11 using. On the other hand, the substrate member 11 is configured to include the substrate 13, the pixel electrode 15, the signal wirings 16 and 17, and the TFT 18. When the TFT 18 is used as a switching element, two types of signal wirings 16 and 17 are prepared, each transmitting a different electric signal.

The same number of pixel electrodes 15 as pixels are arranged in rows and columns along the horizontal and vertical directions H and V on one surface of the light-transmitting insulating substrate 13 on the liquid crystal layer side. The same number of signal lines 16 and 17 as the number of rows and columns of pixels are prepared, and the signal lines 16 and 17 are interposed between the rows and columns of adjacent pixel electrodes 15 and arranged in parallel with each other. Signal wiring 16, 17
Are the gate electrode 19 and the source electrode 20 of the TFT 18.
Connected to each other. The pixel electrode 15 and the signal wiring 16,
17 is electrically connected only through a TFT 18 which is a switching element. On one surface of the substrate 13, an alignment film (not shown) is formed so as to cover the pixel electrode 5, the signal wirings 16 and 17, and the TFT 18.

FIG. 15 is a cross-sectional view of the signal lines 6 and 16 taken along line CC. The signal wires 6 and 16 have a two-layered structure in which the upper wire 21 covers the lower wire 22. Upper layer wiring 21
Is formed of tantalum in order to form an insulating film for electrically blocking the signal wirings 6 and 16 from the outside by using an anodic oxidation method. The lower wiring 22 is formed of aluminum having a specific resistance smaller than that of tantalum in order to reduce the wiring resistance of the signal wirings 6 and 16 as a whole.

On the other hand, a plurality of opposing electrodes having translucency are arranged on one surface on the liquid crystal layer side of an insulating glass substrate having translucency so as to face the pixel electrodes 5 and 15. It has the structure which was done. On one surface of the substrate, a signal wiring for transmitting an electric signal given to the counter electrode is formed. An alignment film is also provided on one surface of the substrate so as to cover the counter electrode. The one and other substrate members are arranged so that one surface on which each electrode of each substrate is formed is opposed to each other, and the signal wires 6, 16 and the signal wires of the other substrate member are orthogonal to each other. Sandwich.

In a TN type liquid crystal layer, the arrangement of liquid crystal molecules in the layer changes depending on the presence or absence of an electric field in the layer. The optical rotation of the liquid crystal layer is lost when a predetermined electric field is generated in the layer. In this device, the presence or absence of optical rotation in the liquid crystal layer of the liquid crystal panel is switched by changing the voltage applied between the pixel electrode 5 and the counter electrode.

Only the light polarized in a direction substantially parallel to the transmission axis of the other polarizing plate on the other substrate member side is incident on the liquid crystal layer. When no electric field is generated and the liquid crystal layer has optical rotation,
The incident light is emitted after the polarization direction is changed by 90 degrees, passes through one polarizing plate on the one substrate member side, and is reflected by the reflecting plate. The reflected light exits the device after passing through the other polarizing plate, the liquid crystal layer, and the one polarizing plate again. At this time, the display state of the pixel is white display. Further, when the optical rotation is lost due to the generation of an electric field, the incident light that has passed through one polarizing plate exits the liquid crystal layer while maintaining the polarization direction, and cannot pass through the other polarizing plate. At this time, the display state of the pixel is black display.

The above-mentioned simple aluminum has a less expensive target for forming a thin film by the sputtering method than other metals having a lower specific resistance value than tantalum. In addition, when the formed thin film is etched by using the photolithography method, an etching solution by a wet method is inexpensive and patterning is easy. Therefore, the lower wirings of the signal wirings 6 and 16 are often formed of simple aluminum.

However, the metal layer of aluminum alone is
It is known that a mass transfer phenomenon called electromigration occurs. Due to this mass transfer phenomenon, hillocks and voids may be generated in the lower wiring 22 composed of a metal layer of aluminum alone.
Hillocks are irregularities on the wiring surface, and voids indicate holes formed in the wiring. When hillocks and voids occur in the lower wiring 22, the upper wiring 21 formed so as to overlap the wiring 22 cannot completely cover the lower wiring 22.

For example, when a hillock is generated, as shown in FIG. 16A, a projection 25 serving as a hillock of the lower wiring 22 penetrates through the conductor layer of the upper wiring 21 and is exposed to the outside. When a void is formed in the lower wiring 22, a recess 26 is also formed in the upper wiring 21 according to the void in the lower wiring 22, as shown in FIG. Extremely thin. On the other hand, in the manufacturing process of the substrate members 1 and 11, after the signal wirings 6 and 16 are formed, the patterning process for the substrate members is repeated a plurality of times in order to form the pixel electrodes 5 and 15 and the switching elements 7 and 18. When an etching process is performed in this patterning process, an etchant may erode into the lower electrode 22 from the vicinity of the convex portion 25 and the concave portion 26 and may etch the lower wiring 22. As a result, FIG.
17 (B) and FIG. 17 (B), cavities 28 and 29 are formed in the lower wiring 22 after the etching process. When the etching process is further repeated, the etchant further penetrates the cavities 28 and 29 to erode the lower wiring 22 and the eroded area increases.

When such cavities 28 and 29 are formed, the wiring resistance of the signal wirings 6 and 16 increases at these portions, which causes uneven lighting. Further, if the cavity is enlarged, it may cause disconnection of the signal wires 6 and 16. Further, when hillocks and voids are generated, the lower wiring 22 is not completely electrically insulated from the surrounding components by the upper wiring 21, so that the pixel electrodes 5, 15 from the lower wiring 22 do not pass through the switching elements 7, 18. In some cases, the electric signal may leak directly.

The present applicant has proposed, in Japanese Patent Application Laid-Open No. Hei 3-137622, a technique for minimizing the erosion of an etching solution caused by hillocks and voids in a wiring substrate using a TFT as a switching element. . In the active matrix substrate disclosed in this publication, the lower wiring is cut so as to be oblique with respect to the extending direction of the wiring and divided into a plurality of discontinuous conductors. The upper wiring is integrally formed so as to continuously cover the plurality of conductors. Even if hillocks and voids are generated in a part of the divided lower layer wiring and are eroded by the etching solution, the erosion is limited only to the conductor in which the hillocks and voids are generated. In the substrate, the generation of hillocks and voids in the lower wiring is not prevented. Therefore, if a hillock or a void occurs, the lower layer wiring is eroded at that portion, and the specific resistance value of the wiring increases.

The applicant of the present application has disclosed Japanese Patent Application Laid-Open No. Hei 3-11852.
In Japanese Patent Publication No. 0, a technique for preventing electromigration in a thin film transistor array used as the one substrate member 11 of the liquid crystal display device described above is proposed. The gate bus line of this thin film transistor array has a configuration in which a lower gate line formed of an alloy containing aluminum which is unlikely to cause electromigration is covered with an upper gate line formed of a conductive material other than the alloy.

[0027]

In the above-mentioned thin film transistor array, a gate bus signal line for supplying an electric signal to a gate electrode of a TFT and a signal line for supplying an electric signal to a source electrode on a substrate form an insulating layer. It is formed so as to be interposed and orthogonal to each other. Although these wirings are electrically insulated individually by the insulating layer, a structure occurs in which an insulating layer is sandwiched between the signal wirings at the intersections of the wirings. Therefore, an additional capacitance is generated at the intersection, thereby inhibiting transmission of an electric signal.

As described above, in the liquid crystal display device,
There is a demand for a bright display screen. In order to perform bright display, it is necessary to increase the aperture ratio and increase the amount of light emitted from the display screen. The aperture ratio is a ratio of the area of the light transmissible area to the area of the displayable area of the display device. When the array is used as one substrate member of a liquid crystal display device, the number of wirings formed on the member increases as compared with the one wiring substrate 1 using MIM elements. Since the signal wiring and the TFT are realized by a metal material that blocks light, the aperture ratio is reduced accordingly. Therefore, when the array is used as one wiring substrate of a reflection type liquid crystal display device,
The brightness of the display screen decreases.

Further, the TFT has a complicated structure as compared with the MIM element, and the number of manufacturing steps is large. Therefore, the manufacturing cost of the TFT is larger than the manufacturing cost of the MIM element. The manufacturing process of the TFT includes a process of heating a substrate member to a high temperature, for example, a process using a chemical vapor deposition method. Therefore, it is necessary to select a material that does not cause distortion and deformation in the high heat treatment for the substrate of the thin film transistor array. Such substrate materials are generally expensive.

An object of the present invention is to provide a wiring board having a two-terminal switching element having a signal wiring which has a small specific resistance value and can prevent generation of hillocks and voids.

[0031]

According to the present invention, there are provided a plurality of electrodes arranged on an insulating substrate, and a plurality of signal wirings arranged on the substrate and supplied with an electric signal to be supplied to each electrode. A wiring board having a two-terminal switching element including a plurality of two-terminal switching elements for individually supplying / cutting an electric signal given to the signal wiring to each electrode, wherein each signal wiring is predetermined. A first wiring having a width; and a second wiring having a width larger than the first wiring and being formed on the first wiring so as to overlap with the first wiring. A wiring substrate having a two-terminal switching element, wherein the wiring substrate is made of a conductive material having a specific resistance smaller than the specific resistance of the conductive material forming the wiring. According to the present invention, the wiring board has a configuration in which a plurality of individual electrodes, signal wires, and two-terminal switching elements are formed on an insulating substrate. Each signal wiring and each individual electrode
They are electrically connected via terminal switching elements. The number of signal wirings is smaller than that of individual electrodes, and a plurality of individual electrodes are connected to a single signal wiring. Each signal wiring is provided with an electric signal to be supplied to a plurality of connected individual electrodes. The two-terminal switching element is, for example, a MIM element that is a two-terminal nonlinear element, and is prepared for each individual electrode. The element transmits an electric signal transmitted through the signal wiring,
Supply / cut off to each individual electrode individually. by this,
Of the group of individual electrodes electrically connected to the same signal wiring, the same electric signal is given to only some of the individual electrodes. Each signal wiring is formed by at least partially overlapping a first wiring and a second wiring. The conductive material forming the first wiring is a conductive material containing aluminum, and a conductive material having a specific resistance smaller than that of the conductive material forming the second wiring is used. As the material,
For example, an alloy composed of aluminum and silicon can be used. The wiring resistance value of signal wiring made of the same conductive material is
It increases as the length of the wiring increases. Also, it increases as the cross-sectional area of the wiring decreases. When the wiring resistance of the signal wiring increases, attenuation and distortion occur in the signal while the electric signal given to the signal wiring is transmitted through the wiring.
Therefore, an individual electrode electrically connected to the wiring near one end where an electric signal is input and an individual electrode electrically connected near the other end opposite to the one end of the signal wiring. The level and waveform of the applied electric signal are different from those of the electrode. When the signal wiring is a wiring having the above-described two-layer structure, the wiring resistance can be reduced as compared with a signal wiring formed in the same shape using only the conductive material of the second wiring. therefore,
Even when the wiring length of the signal wiring is long and the cross-sectional area is small, the electric signal can be transmitted from one end to the other end of the signal wiring without attenuation and distortion. As a wiring having such a two-layer structure, a wiring in which a first wiring and a second wiring made of simple aluminum are overlapped is known. Since simple aluminum has a small specific resistance and a high electric conductivity, the wiring resistance of the signal wiring can be reduced. However, a single aluminum wiring is liable to change its shape due to so-called electromigration. The second wiring is formed by laminating a thin film of a conductive material of the second wiring on the lower first wiring and patterning the thin film. When the above-mentioned shape change occurs in the first wiring, the shape of the thin film formed by being laminated on the wiring also changes, and the thickness of the thin film becomes extremely thin at that portion or the first wiring is exposed. There is. If the thin film is subjected to an etching treatment, an etchant may enter the first wiring through the thin film at a portion where the shape of the first wiring changes, and the first wiring may be etched and damaged. When the first wiring is damaged, the wiring resistance of the signal wiring increases at the damaged portion. Therefore, it causes attenuation and distortion of the electric signal transmitted through the signal wiring. When a mixed material containing aluminum (hereinafter, referred to as an “Al mixed material”) is obtained by adding an impurity to single aluminum, it is possible to prevent a change in the shape of the wiring due to electromigration. Therefore, when the second wiring is further formed on the first wiring formed of the Al mixed material, the thin film of the conductive material of the second wiring is not affected by the shape change. Therefore, it is possible to prevent the first wiring from being erroneously etched during the etching of the thin film. Thus, it is possible to prevent an increase in the wiring resistance value of the signal wiring due to a change in the shape of the first wiring. The Al mixed material has a smaller specific resistance value and a higher electric conductivity than other conductive materials containing no aluminum. In addition, the Al mixed material has a lower energy barrier compared to other conductive materials at the junction with p-type and n-type silicon, and can form a good semiconductor-metal bond (ohmic contact). it can. Further, since a chemically stable oxide layer can be formed on the surface, it is hardly corroded. Therefore, the Al mixed material is more suitable as a wiring material for wiring in a wiring board than other conductive materials. Further, the thin film of the Al mixed material is easier to perform the etching process than the thin film of another conductive material containing no aluminum. Further, when performing a wet etching process, it is easy to obtain an etchant used for the process. Further, when a thin film of an Al mixed material is formed, a high-purity target used in a film forming technique such as a sputtering method and an evaporation method can be easily obtained at low cost. Also,
Using this target, a high-purity thin film can be easily formed. Therefore, the implementation is easier as compared with the case where another metal material is used. In such a wiring board, the area occupied by the signal wiring and the switching element in the substrate area is smaller than that of a wiring board having a structure using a TFT for the element. Therefore, when the wiring substrate is used as a substrate member of a liquid crystal display device, the aperture ratio of the device can be improved. Therefore, a liquid crystal display device with a bright display can be realized.

According to the present invention, there are provided a plurality of electrodes arranged on an insulating substrate, a plurality of signal wirings provided on the substrate and supplied with an electric signal to be supplied to each electrode, and a plurality of signal wirings provided on the signal wirings. A wiring board having a two-terminal switching element having a plurality of two-terminal switching elements for individually supplying / cutting the applied electric signal to / from each electrode, wherein each signal wiring has a first width having a predetermined width. A wiring having a larger width than the first wiring and having a second wiring formed so as to overlap with the first wiring, wherein the first wiring has a first conductor layer made of aluminum; A second conductive layer made of a conductive material having a specific resistance smaller than that of the conductive material forming the second wiring, wherein the second conductive layer is formed of a first conductive layer and a second conductive layer. Are formed so as to be interposed between the second wiring and the second wiring. Resistivity of the conductor material is a circuit board having a two-terminal switching element being greater than the resistivity of aluminum. According to the present invention, the wiring board has a configuration in which a plurality of individual electrodes, signal wires, and two-terminal switching elements are formed on an insulating substrate. The arrangement state of these components is the same as that of the wiring board according to the first aspect. The signal wiring is formed by laminating the first and second wirings. The lower first wiring has a stacked structure in which a plurality of conductor layers are stacked. When this wiring substrate is used as a substrate member of a liquid crystal display device, a brighter display can be obtained by improving the aperture ratio of the device as compared with a substrate member using a TFT as a switching element. The plurality of conductor layers of the first wiring include the first and second conductor layers. The first conductor layer is made of simple aluminum (A
l). The second conductor layer is a conductor material other than simple aluminum and is made of a material having a lower specific resistance than the conductor material of the second wiring. Further, the specific resistance of the conductive material forming the second wiring is larger than the specific resistance of aluminum. Thus, the first wiring is formed by laminating a plurality of layers of a plurality of conductive materials having a specific resistance smaller than that of the conductive material of the second wiring. Therefore, it can be considered that the specific resistance of the entire first wiring is smaller than the specific resistance of the second wiring. Therefore, the wiring resistance of the signal wiring having the above-described configuration is smaller than the wiring resistance of the same-shaped signal wiring formed of only the conductive material of the second wiring. Therefore, it is possible to prevent the attenuation and distortion of the electric signal transmitted through the signal wiring. The first wiring is formed by laminating the second conductive layer so as to be interposed between the first conductive layer and the second wiring. If at least one second conductive layer is stacked at this position, the number and order of the plurality of conductive layers stacked below the second conductive layer are not limited. May be. For example, the first and second conductor layers are sequentially and alternately stacked. A third conductor layer made of a conductor material different from the conductor material of the first and second conductor layers;
One or more first to third conductor layers are stacked. As the plurality of conductive materials forming the first wiring in this way, any material may be used as long as the specific resistance value is smaller than the conductive material of the second wiring. If the first conductor layer made of simple aluminum does not directly contact the second wiring, the laminated structure of the first wiring can be an arbitrary structure. Simple aluminum has the same characteristics as the above-described Al mixed material, and is more suitable as a wiring material for wiring in a wiring board than other conductive materials. However, as described above, a shape change due to electromigration is likely to occur in a single aluminum wiring. By laminating a thin film of another material on the single aluminum wiring, it is possible to prevent the shape change from occurring. As the thin film material, a conductive material and an insulating material can be used. It is preferable that a thin film made of a conductive material be laminated on a single aluminum wiring because the first wiring and the second wiring are electrically connected to each other over the entire wiring surface. With the first wiring having the above-described configuration, it is possible to prevent a change in the shape of the first wiring due to electromigration. Further, even if the shape changes, it is difficult for the changed portion to penetrate the second conductive material and reach the second wiring. Therefore, the shape change does not affect the second wiring. Therefore, it is possible to prevent the first wiring from being damaged in the manufacturing process due to the shape change, thereby preventing an increase in the wiring resistance value of the signal wiring and disconnection of the signal wiring.

According to the present invention, the width of the overlapping portion of the first wiring and the second wiring is at least 1 μm or more. According to the present invention, in the wiring board, the second wiring is formed such that at least one portion overlaps the first wiring. The width of the overlapping portion is at least 1 μm or more. Also the second
When the wiring is formed so as to completely cover the first wiring, it is possible to prevent an electric signal from leaking from the first wiring directly to the individual electrode. The above-described wiring board is used, for example, as a wiring board member of an active matrix drive type liquid crystal display device. In this wiring board member, in order to increase the aperture ratio, it is preferable that the width of the non-light-transmitting signal wiring be as narrow as possible. When the width of the signal wiring is reduced, the specific resistance value of the signal wiring generally increases. The wiring resistance value of the signal wiring including the first and second wirings decreases as the width of the overlapping portion of the first and second wirings increases. Therefore, in order to increase the aperture ratio and reduce the specific resistance value of the signal wiring, it is preferable that the signal wiring has an overlapping portion having a width as wide as possible. The first and second wirings cover a desired portion of the thin film of the conductive material formed on the insulating substrate with a photoresist layer having a shape equivalent to the wiring shape, and are not covered with the layer of the thin film. The remaining portion is formed by removing by an etching process. In this etching process and photolithography process for forming a photoresist layer, it is difficult to perform fine processing of 1 μm or less. For such a reason, it is preferable that the width of the overlapping portion of the signal wiring is at least 1 μm or more.

According to the present invention, the two-terminal switching element includes a first electrode electrically connected to the signal wiring and integrally formed, and a second electrode electrically connected to the pixel electrode.
A two-terminal nonlinear element formed by laminating an electrode and an insulator layer interposed between the first and second electrodes, wherein the conductive material of the second wiring includes at least tantalum. I do. According to the present invention, the two-terminal switching element has a configuration in which first and second element electrodes are stacked with an insulator layer interposed therebetween. The first and second element electrodes are formed of a conductive material, for example, a metal. The signal wiring is formed integrally with the first element electrode and is electrically connected. Each individual electrode is electrically connected to the second element electrode. The two-terminal nonlinear element having such a configuration is a so-called metal-insulator-metal (MIM) element. Further, the conductive material of the second wiring includes at least tantalum (Ta). That is, the material is realized by simple tantalum and a tantalum-based metal that is a tantalum metal compound. Since the first element electrode is formed integrally with the signal wiring, the electrode has at least a single-layer structure of a tantalum-based metal or a stacked structure of a tantalum-based metal and an aluminum-based metal. The tantalum-based metal is exposed on the surface of this electrode. When a thin film layer of a tantalum-based metal is subjected to an oxidation treatment using an anodic oxidation method, tantalum oxide (TaO _x )
Is formed. The anodic oxide film functions as an insulator layer. An anodic oxide film of tantalum oxide (TaO _x ) generally has little contamination with impurities and has high insulation properties. The thickness of the anodic oxide film can be easily adjusted by changing the value of the formation voltage in anodic oxidation. Therefore, when the first device electrode is the lower electrode of the MIM device, the insulator layer laminated thereon is replaced with a tantalum oxide (T
aO _x ). Also,
In the anodic oxidation treatment for obtaining the insulator layer, the surface of the signal wiring is also anodized. With this, MIM
Simultaneously with the process of forming the insulator layer of the element, an insulator film covering the signal wiring can be formed. When the signal wiring is covered with such an insulating film and insulated, electric signals can be prevented from leaking from the signal wiring directly to the individual electrodes.

[0035]

FIG. 1 is a sectional view showing a simplified structure of a liquid crystal display device 61 according to one embodiment of the present invention. FIG. 2 is a front view showing the appearance of the liquid crystal display device 61. FIG. The liquid crystal display device 61 is a reflection type liquid crystal display device of a TN type which is of an active matrix drive system. The device 61 performs monochrome display.

In the displayable area of the display screen of the device 61, 1024 pixels each along the horizontal direction H and 768 pixels (1024 × 768) along the vertical direction V are arranged in a matrix. . Such a pixel array is an XGA
Pixel array. The above-described cross-sectional view of FIG. 1 corresponds to the A-A cross-sectional view of the liquid crystal display device 61 of FIG.

Each pixel takes a display state of either white display or black display in the display screen. The white display is a state in which light can pass through the inside of the device 61 and a state in which light is emitted from the display screen. The black display is a state in which light to be emitted from the display screen is blocked. The device 61 visually displays a desired image on a display screen by combining pixels whose display states are individually switched.

The liquid crystal display device 61 has a configuration in which a liquid crystal panel 63 is sandwiched between a pair of polarizing plates 64 and 65. The polarizing plates 64 and 65 are arranged such that their transmission axes are orthogonal to each other when viewed from the normal direction U of the device 61. Further, on the opposite side of the polarizing plate 65 from the liquid crystal panel 63, a reflection plate (not shown) is provided. In the liquid crystal display device 61, the polarizing plate 64 side is a display screen that is a light incident surface and a light emitting surface. The liquid crystal panel 63 has a configuration in which a liquid crystal layer 69 is sandwiched between substrate members 67 and 68 described below. The liquid crystal layer 69 is formed of, for example, a nematic liquid crystal material.

FIG. 3 is a partial plan view showing a detailed configuration of the substrate 67 on the side of the reflection plate and the polarizing plate 65 of the liquid crystal panel 63 of the liquid crystal display device 61 of FIG. FIG. 4 is a sectional view of the substrate member 67 taken along line BB of FIG. 1, 3 and 4 will be described together.

The substrate member 67 includes a substrate 71, a pixel electrode 7
3, signal wiring 74, MIM element 75, and alignment film 76
It is comprised including. The substrate 71 is formed of a light-transmitting insulating substrate material. On one surface 72 of the substrate 71 on the liquid crystal layer 69 side, the pixel electrodes 73 are arranged in a predetermined arrangement described later.
The signal wiring 74 and the MIM element 75 are formed. Further, on the one surface 72 side of the substrate 71, each of the components 73 to 7
5 is formed so as to cover the substrate member 67.
Is formed. The substrate member 67 is connected to one surface 7 of the substrate 71.
The two sides are arranged so as to be in contact with the liquid crystal layer 69.

The substrate 71 has a light transmitting property and an insulating property. Such a substrate 71 is made of, for example, Corning #
Implemented in 7059 Fusion Pyrex glass. Alternatively, an insulating base coat film may be formed on the entire surface of one surface 72 of the substrate 71, and the constituent elements 73 to 75 may be formed on the base coat film. The base coat film is realized by, for example, tantalum oxide (TaO _x ) which is an insulating material. When a base coat film is formed on one surface 72 of the substrate 71, during the manufacture of the substrate member 67, the impurities from the substrate 71 are removed by the components 73
To 75 to prevent each component from being contaminated. Further, entry of impurities into the liquid crystal layer 69 can be prevented. Thereby, each of the constituent elements 73 to 7
5, especially the element characteristics of the MIM element 75 can be improved. Further, since the deterioration of the liquid crystal can be prevented, the voltage holding ratio can be kept good.

The same number of pixel electrodes 73 as the number of pixels of the liquid crystal display device 61 are prepared. The pixel electrodes 73 are arranged in a matrix on the one surface 72 of the substrate 71 in parallel along the horizontal direction H and the vertical direction V. Hereinafter, a group of components arranged in a straight line along the horizontal direction H is referred to as a “row”. A group of components arranged on a straight line along the vertical direction V is referred to as a “column”. The pixel electrode 73 is realized with a light-transmitting conductive material.
Examples of the light-transmitting conductive material include tin-indium oxide (ITO).

The signal lines 74 are formed in the same number as the number of columns of the pixel electrodes 73. Each signal wiring 74 is connected to the pixel electrode 73
Are extended from one end to the other end of the substrate 71 in parallel with each row. The signal lines 74 are arranged in parallel with each other with an interval. One column of pixel electrodes 73 is interposed between two adjacent signal lines 74.

The signal wiring 74 has a laminated structure in which an upper wiring 78 and a lower wiring 79 are overlapped. The upper wiring 78 and the lower wiring 79 are each realized by a conductive material having a low wiring resistance. Further, as the conductive material forming the lower wiring 79, it is preferable to use a conductive material having a lower specific resistance value than the conductive material forming the upper wiring 78. In the device 61, tantalum (Ta) is used as a conductive material of the upper wiring 78. As the conductive material of the lower wiring 79, an aluminum compound having a specific resistance smaller than that of tantalum is used. As the aluminum compound, a mixed material (Al-Si) obtained by adding silicon (Si) to aluminum (Al) is exemplified. This mixed material (Al-S
The addition ratio of silicon in i) is 8 wt%, and the specific resistance value of the mixed material is 4.8 μΩ · cm. Hereafter, the substance α
And a substance β are referred to as an (α-β) mixed material.

The wiring width of the lower wiring 79 is 5-10.
μm is preferred. Further, it is preferable that the width W1 of the overlapping portion where the upper wiring 78 and the lower wiring 79 overlap is 1 μm or more. Further, it is preferable that the upper layer wiring 78 completely covers the lower layer wiring 79 and completely shields the lower layer wiring 79 from the outside. In the wiring board 67 of this embodiment, the width of the lower wiring 79 is 8 μm, and the width of the upper wiring 78 is 1
It is formed so as to be 8 μm, and the longitudinal center lines of the upper layer wiring and the lower layer wiring 79 coincide when viewed from the normal direction U. Thus, the upper layer wiring 78 is formed to be larger by 5 μm on both sides in the width direction of the wiring than the lower layer wiring 79, and can cover the lower layer wiring 79. The width W1 of the overlapping portion is equal to the wiring width of the lower wiring 79, that is, 8 μm.

The same number of MIM elements 75 as the number of pixel electrodes 73 are prepared. The MIM elements 75 individually electrically connect the pixel electrodes 73 in each column to the signal wiring 74 adjacent to the column. The MIM element 75 includes a lower electrode 81, an insulator layer 82,
In addition, the upper electrode 83 is formed by being stacked in order from the bottom. The lower electrode 81 is electrically connected to the signal wiring 74. The upper electrode 83 is electrically connected to the pixel electrode 73.

The MIM element 75 is a switching element, and supplies or cuts off an electric signal transmitted via the signal wiring 74 for each electrode 73 individually. MIM element 75
Has a non-linear current-voltage characteristic in which the resistance value increases when the voltage value of the input signal is small, and decreases when the voltage value of the input signal is large enough to drive the liquid crystal. . An active matrix driving method using the MIM element 75 as a switching element is as follows.
The non-linear current-voltage characteristic of the MIM element 75 is applied to switching of supply / cutoff of a signal to be supplied from the signal wiring 74 to the pixel electrode 73.

The lower electrode 81 has a laminated structure in which an upper layer 85 and a lower layer 86 are overlapped. Upper layer 85
Is formed so as to cover the lower layer portion 86 and shield it from the outside. The upper layer portion 85 includes an upper layer wiring 78 of the signal wiring 74.
Is electrically connected to Lower layer portion 86 is electrically connected to lower layer wiring 79 of signal wiring 74. The relationship between the material and shape of the upper layer portion 85 and the lower layer portion 86 and the specific resistance of the conductive material is the same as the relationship between the upper layer wiring 78 and the lower layer wiring 79. In the device 61 of the present embodiment, the upper layer 85
And the lower layer part 86 includes an upper wiring 78 and a lower wiring 79.
Are formed integrally with the same conductive material.

Therefore, upper layer portion 85 of lower electrode 81 is realized by, for example, tantalum (Ta). The lower layer portion 86 of the lower electrode 81 is realized by a (Al-Si) mixed material.
The insulator layer 82 is made of, for example, tantalum oxide (TaO).
_x ). The upper electrode 83 is realized by titanium (Ti).

The alignment film 76 covers the pixel electrode 73 having the above-described structure, the signal wiring 74, and the MIM element 75. The surface of the alignment film 76 is subjected to an alignment process for aligning the molecular axes of the liquid crystal molecules with an alignment process direction which is a predetermined direction. For the orientation treatment, for example, an oblique deposition method and a rubbing method are used.

FIG. 5 shows the liquid crystal panel 6 of the liquid crystal display device 61.
3 is a partial plan view showing a detailed configuration of a substrate member 68 on the display screen side of FIG. FIG. 1 and FIG. 5 will be described together.

The substrate member 68 includes a substrate 91 and a counter electrode 9.
3 and an orientation film 94. Substrate 91
Is an insulating substrate having a light-transmitting property.
Of the same material as the substrate 71 of FIG. A plurality of strip-shaped opposing electrodes 93 are formed on one surface 92 of the substrate 91 on the liquid crystal layer 69 side. Further, an alignment film 94 is formed on one surface 92 so as to cover each counter electrode 93. The surface of the alignment film 94 is subjected to the above-described alignment processing along a predetermined alignment processing direction orthogonal to the alignment processing direction of the alignment film 76 of the substrate member 67.

Each of the opposing electrodes 93 is an electrode to be provided in a region of the pixel electrode 73 of the substrate member 67 which faces a group of pixel electrodes 73 belonging to the same row, and a scanning signal wiring for transmitting a scanning signal to the electrode. Are integrated. The same number of the counter electrodes 93 as the number of rows of the pixel electrodes 73 are prepared,
When the liquid crystal panel 63 is viewed from the normal direction U, the pixel electrodes 7
3 is formed at a position facing each row. At this position, each counter electrode 93 is in the horizontal direction H of the substrate 91, respectively.
From one end to the other end in a straight line. The extending direction of the counter electrode 93 is orthogonal to the extending direction of the signal wiring 74 when viewed from the normal direction U. Further, the respective counter electrodes 93 are arranged in parallel with each other at predetermined intervals along the vertical direction V. The counter electrode 93 is formed of a light-transmitting conductive material. The material includes, for example, tin-indium oxide (ITO).

Referring back to FIG. A plurality of terminals 98 are provided at one end 97 of the substrate member 67 in the vertical direction V. Each terminal 98 is electrically connected to signal wiring 74. A plurality of terminals 100 are provided at one end 99 of the substrate member 68 in the horizontal direction H. Each terminal 10
0 is electrically connected to the counter electrode 93, respectively. The terminals 98 and 100 are for connecting the device 61 to a device for applying a desired electric signal to the signal wiring 74 and the counter electrode 93.

Referring again to FIG. The cells of the liquid crystal panel 63 include the substrate members 67 and 68 having the above-described configuration,
One surface 72, 92 side of the substrates 71, 91 are opposed to each other, and are bonded at predetermined intervals. The predetermined interval is, for example, 5 μm. This interval is
For example, it is held by a sealing material that seals around the substrate members 67 and 68. At this time, each of the substrate members 67, 68
Are arranged such that the extending direction of the signal wiring 74 and the extending direction of the counter electrode 93 are orthogonal to each other when viewed from the normal direction U.
Further, the rubbing axes indicating the orientation directions of the alignment films 76 and 94 are orthogonal to each other when viewed from the normal direction U when the substrate members 67 and 68 are arranged as described above. The liquid crystal made of the above-described liquid crystal material is injected into the gaps between the cells formed as described above to form the liquid crystal panel 63. A single pixel region 96 of the liquid crystal panel 63 is shown in FIGS.

The liquid crystal display device 61 of this embodiment has a MIM element 7 which is a non-linear two-terminal element as a switching element.
5 is an apparatus utilizing the nonlinearity of the element resistance of the element. In such a device, when the element capacitance of the two-terminal element is larger than the liquid crystal capacitance of the liquid crystal layer of the pixel to which the element belongs, when a voltage is applied between the electrodes 73 and 93 of the pixel, the element other than the pixel A voltage may be applied between the electrodes. As a result, for example, there may be a problem that crosstalk occurs in which the contrast of an image is reduced. To prevent this crosstalk, 2
When an MIM element is used as a terminal element, the ratio between the element capacitance and the liquid crystal capacitance is preferably set to 1:10. When the MIM element 75 having such a capacitance ratio is used, good element characteristics can be obtained in each pixel.

Referring back to FIG. Among the liquid crystal molecular axes 102 which are the long axes of the liquid crystal molecules 101 in the liquid crystal layer 69, the liquid crystal molecule axis 1 of the liquid crystal molecule 101 a closest to the substrate member 67.
02a coincides with the rubbing axis indicating the direction of the alignment treatment of the alignment film 76 of the substrate member 67. The liquid crystal molecular axis 102 b of the liquid crystal molecule 101 b closest to the substrate member 68 among the liquid crystal molecular axes 102 coincides with the rubbing axis of the alignment film 94 of the substrate member 68. Since the rubbing axes of the alignment films 76 and 94 are orthogonal to each other when viewed from the normal direction U, the liquid crystal molecules 101
The liquid crystal molecular axes 102a and 102b of a and 101b are also orthogonal to each other when viewed from the normal direction U. Thereby, the twist angle of the liquid crystal molecules in the liquid crystal layer 69 is adjusted to 90 °.

The arrangement of the liquid crystal molecules 101 in the liquid crystal layer 69 made of a nematic liquid crystal material changes according to the presence or absence of an electric field in the liquid crystal layer 69. The presence or absence of an electric field in the liquid crystal layer 69 is determined for each pixel by the electrodes 73,
It is switched by changing the voltage applied between 93.

For example, when a predetermined voltage is not applied between the pixel electrode 73 and the counter electrode 93 in an arbitrary pixel region 96, no electric field is generated in the liquid crystal layer 69.
At this time, the molecular arrangement of the liquid crystal molecules 101 in the portion of the liquid crystal layer sandwiched between the electrodes 73 and 93 in the region 96 is changed according to the alignment film 7.
6,94 orientation directions. At this time, the liquid crystal molecule axes of the liquid crystal molecules 101 are aligned with the substrate members 67 and 68.
Is substantially parallel to one surface, and its twist angle is kept at 90 °. Therefore, in this state, the light incident on the pixel propagates along the liquid crystal molecule axis of each liquid crystal molecule 101 and is emitted after the polarization direction is bent by 90 °.

When a predetermined voltage is applied between the pixel electrode 73 and the counter electrode 93 in the region 96, an electric field is generated between the two electrodes 73 and 93. At this time, the molecular arrangement of each liquid crystal molecule 101 in the liquid crystal layer 69 in the region 96 is defined by the direction of the generated electric field. At this time, the liquid crystal molecule axis 102 of each liquid crystal molecule 101 extends along the electric field direction of the generated electric field and is substantially orthogonal to the surfaces of the substrate members 67 and 68.
As a result, the optical rotation of the liquid crystal layer 69 is lost. Therefore, in this state, light incident on the liquid crystal layer 69 of the pixel is emitted while maintaining the polarization direction. As described above, by adjusting the voltage applied between the pixel electrode 73 and the counter electrode 93, the arrangement of the liquid crystal molecules 101 in the liquid crystal layer 69 interposed between the two electrodes 73 and 93 is changed. Switches the presence or absence of optical rotation.

As described above, the transmission axes of the polarizing plates 64 and 65 sandwiching the liquid crystal panel 63 are orthogonal to each other. Further, the transmission axis of the polarizing plate 64 and the rubbing axis of the alignment film 94 of the substrate 68 are parallel. Also, the polarizing plate 65 and the substrate member 6
7 is parallel to the rubbing axis of the alignment film 76.

Therefore, when a predetermined voltage is not applied between the electrodes 73 and 93, the incident light that has entered the liquid crystal panel 63 via the polarizing plate 64 has its polarization direction bent by 90 ° and exits from the liquid crystal panel 63. The light passes through the polarizing plate 65 and is reflected by the reflecting plate. The reflected light passes through the polarizing plate 65 again, and the polarization direction is again bent by 90 ° in the liquid crystal panel 63, and then passes through the polarizing plate 64 and is emitted. Thus, the display state of the pixel in this state is white display. When a predetermined voltage is applied between the electrodes 73 and 93, the incident light that has entered through the polarizing plate 64 passes through the liquid crystal panel 63 while maintaining the polarization direction, and
Reaches 5. Since the polarization direction of the incident light coincides with the direction of the transmission axis of the polarizing plate 64, the incident light cannot pass through the polarizing plate 65. Therefore, in this state, the pixel is in a black display state. As described above, in the liquid crystal display device 61, display is performed by changing the display state of each pixel by changing the voltage applied between the electrodes 73 and 93 of each pixel.

As described above, the reflection type liquid crystal display device 61 transmits incident light incident on the device 61 from outside to the liquid crystal layer 6.
After 9 passes, display is performed by the reflected light reflected by the reflector. Therefore, there is no light source required for a so-called transmission type liquid crystal display device. Therefore, the power consumption of the device can be reduced, and the device can be made thinner and lighter. Such a liquid crystal display device is expected to be used, for example, as a display device of a portable information terminal. In particular, as a display device for this purpose, a reflective liquid crystal display device having a bright display screen called paper white and having high resolution and capable of large-capacity display is suitable.

FIG. 6 is a step-wise sectional view for explaining a method of manufacturing the substrate member 67 of the liquid crystal panel 63 of the liquid crystal display device of FIG. Hereinafter, a manufacturing process of the substrate member 67 will be described.

First, a thin film of an (Al—Si) mixed material, which is a conductive material of the lower wiring 79 of the signal wiring 74 and the lower layer 86 of the lower electrode 81, is formed on one surface 72 of the substrate 71 by a sputtering method. I do. The thickness of the thin film is about 2
00 nm. Next, a photoresist film mask having the same shape as the lower wiring 79 of the signal wiring 74 and the lower layer 86 of the lower electrode 81 is formed on the thin film by photolithography. Subsequently, an etching process is performed on the substrate 71 whose surface is covered with the mask, thereby forming the lower wiring 79 and the lower layer 86 of the lower electrode 81.

The above-described photolithography processing and etching processing are collectively referred to as patterning processing.
In the photolithography process, first, a thin film of a photoresist is formed on a thin film of a desired material to be processed.
A mask suitable for the wiring pattern to be formed of the material of the thin film to be processed is overlaid on this thin film, exposed and developed. Thereby, depending on the photosensitivity of the photoresist,
Only one of the exposed portion and the unexposed portion is removed. On the thin film of the desired material, the remaining portion of the photoresist is left in the same shape as the wiring pattern, and covers the thin film. As described above, when the etching process is performed on the thin film of a desired material covered with the photoresist film mask that matches the wiring pattern, only the portion of the photoresist film that is not covered with the mask is etched and removed. . As a result, the thin film is processed, and a wiring pattern formed of a desired material is formed. When the etching process is completed, the photoresist film is removed by a predetermined chemical process.

Next, on one surface 72 of the substrate 71, a thin film of a conductive material which covers the lower layer 79 and the lower layer 86 of the lower electrode 81 and forms the upper layer 85 of the upper layer 78 and the lower electrode 81. Is formed using a sputtering method. For example, tantalum (Ta) is used as the conductive material. The tantalum thin film is formed, for example, by a DC sputtering method using a tantalum sintered target containing 2 mol% to 10 mol% of nitrogen. The thickness of the thin film is, for example, 300 nm. Next, a patterning process is performed on the formed conductor thin film to form an upper layer 8 of the upper wiring 78 and the lower electrode 81.
A conductive layer 106 having substantially the same shape as that of No. 5 is formed. The substrate member formed in this way is shown in FIG.
Shown in

For example, when the conductive material is tantalum (Ta)
In this case, the thin film of the conductive material is etched by a dry etching method using a mixed gas of CF ₄ and oxygen (O ₂ ). In addition, in addition to the dry etching method, a wet etching method using an etching solution that is hydrofluoric nitric acid may be used for the etching of the tantalum thin film. The wet etching method has a higher processing speed in the etching processing than the dry etching method. Therefore, the throughput of manufacturing the substrate can be improved.

Subsequently, the surface of the conductor layer 106 is oxidized using an anodic oxidation method. Thus, the surface portion of the conductor layer 106 is oxidized, and an oxide layer having a predetermined thickness is formed. Tantalum oxide (TaO) which is an oxide of tantalum
_x ) is an insulator material. Thereby, the conductor layer 10
The oxide layer on the surface of No. 6 functions as an insulator layer. The remaining portion of the conductor layer 106 that is not oxidized becomes the upper layer 85 of the upper wiring 78 and the lower electrode 81. The signal wiring 74 composed of the upper wiring 78 and the lower wiring 79
Is covered with the oxide layer of the insulator and is electrically isolated from the outside. Further, an insulator layer 82 made of the oxide is formed on the surface of the lower electrode 81 composed of the upper layer portion 85 and the lower layer portion 86. The thickness of the insulator layer covering the insulator layer 82 and the signal wiring 74 is, for example, about 60 nm. FIG. 6B shows the substrate member formed in this manner.

For example, when conductor layer 106 is made of tantalum (T
When formed in a), a 1% ammonium tartrate solution is used as the electrolyte used for the anodic oxidation method. The processing temperature is set to 25 ° C. Furthermore, the formation current was increased to 0.18 mA / unit area per anodized area.
cm ² and the formation voltage is 31 V.

When an oxide layer is formed by anodizing the conductive layer using the anodic oxidation method, the thickness of the oxide layer is proportional to the formation voltage. Since the electrical resistance of the insulator layer increases as its thickness increases, dielectric breakdown due to static electricity hardly occurs. Therefore, to prevent the dielectric breakdown,
It is preferable to increase the thickness of the insulator layer. However, when the thickness of the insulator layer is increased, the voltage-current characteristics of the MIM element 75 deteriorate. Therefore, in the MIM element 75 of the present embodiment, it is preferable that the thickness of the insulator layer, which is the oxide layer, be about 60 nm.

Subsequently, a thin film of a conductive material for forming the upper electrode 83 is formed on one surface 72 of the substrate 71 so as to cover the signal wiring 74 and the insulator layer 82, and the thin film is subjected to a patterning process. . Thus, the upper electrode 83 is formed by being laminated on the insulator layer 82. Thereby, the lower electrode 81, the insulator layer 82, and the upper electrode 83
Are stacked to form an MIM element 75.
FIG. 6C shows the substrate member on which the MIM element 75 is formed.

Subsequently, a thin film of a conductive material for the pixel electrode 73 is formed on one surface 72 of the substrate 71 so as to cover the signal wiring 74 and the MIM element 75, and the thin film is subjected to a patterning process. As a result, one surface 72 of the substrate 71
The pixel electrode 73 is formed. At this time, the pixel electrode 73
Is formed so as to overlap with an end of the upper electrode 83 of the MIM element 75. Thereby, the upper electrode 83
And the pixel electrode 73 are electrically connected. The substrate member formed in this way is shown in FIG.

Finally, a thin film made of the material of the alignment film 76 is formed on one surface 72 of the substrate 71 so as to cover the pixel electrode 73, the signal wiring 74, and the MIM element 75, and the surface of the thin film is subjected to a rubbing process. . Thereby, the alignment film 76
Is formed. By such a series of processing operations, the substrate member 67 shown in FIG. 3 is formed.

The signal wiring 74 of the wiring board 67 thus formed is made of only the insulator material of the upper wiring 78 of tantalum (Ta) formed on one substrate member of the liquid crystal display device of the first prior art. The wiring resistance can be reduced as compared with the signal wiring formed by the method. Further, in the signal wiring having the laminated structure, it is possible to prevent the occurrence of voids and hillocks due to electromigration, as compared with the case where the lower wiring 79 is formed of simple aluminum (Al).

FIG. 7 is a step-by-step cross-sectional view for explaining a manufacturing process of the one-sided substrate member, which is a comparative example of the above-described substrate member 61. On the other hand, the substrate member is a substrate member on the side of the reflection plate of the liquid crystal panel of the TN type reflection type liquid crystal display device of the active matrix driving system according to the first prior art. The board member has a similar configuration to the board member 67 of the present embodiment, and the same components are denoted by the same reference numerals,
Description is omitted. The manufacturing process of the substrate member will be described below. The manufacturing process is performed by the substrate member 6 of the present embodiment shown in FIG.
7 has steps similar to those of FIG. 7, and a detailed description of the same steps will be omitted.

First, a thin film of tantalum (Ta) is formed on one surface of a light-transmitting insulating substrate 71 by a sputtering method, and the thin film is subjected to a patterning process. As a result, a conductor layer 106 having substantially the same shape as the signal wiring 108 and the lower electrode 109 is formed.
This state is shown in FIG. Next, the conductor layer 106
Is oxidized by anodic oxidation to form an insulator layer 82 made of tantalum oxide (TaO _x ) and a signal wiring 10.
8 is formed. The remaining portion of the conductor layer 106 that is not oxidized becomes the signal wiring 108 and the lower electrode 109. This state is shown in FIG.

Subsequently, a thin film of titanium (Ti) is formed on one surface of the substrate 71, and the thin film is subjected to a patterning process to form an upper electrode 83. This state is shown in FIG. Thus, the MIM element 75 is formed on the substrate 71. Further, a thin film of tin-indium oxide (ITO) is formed on the one surface, and the thin film is subjected to a patterning process to form a pixel electrode 73. This state is shown in FIG. Finally, an alignment film (not shown) is formed on the one surface, and a one-sided substrate member is formed.

When the manufacturing process of the substrate member 67 of the present embodiment is compared with the manufacturing process of the substrate member as a comparative example, the manufacturing process of the present embodiment is different from the manufacturing process of the comparative example in that the lower layer wiring 79 and It can be seen that a step of manufacturing the lower layer portion 86 of the lower electrode is added. As described above, the manufacturing process of the substrate member 67 can be realized only by adding a single process to the conventional manufacturing process of the substrate member. Also, the added step is a step of performing a thin film formation and a patterning process, and is easy to carry out.

The conductive material of the lower wiring 79 of the signal wiring 74 of the liquid crystal display device 61 of the present embodiment includes aluminum, and has a specific resistance smaller than that of the conductive material of the upper wiring 78. Is selected. The conductive material of the upper wiring 78 and the lower wiring 79 is tantalum (Ta).
Alternatively, a conductive material other than the (Al-Si) mixed material may be used.

Tantalum (Ta) has a relatively small specific resistance value compared to other metals, and has low wiring resistance. Further, tantalum is formed by using an anodizing method with tantalum oxide (Ta).
A uniform insulator layer made of O _x ) can be easily formed. Therefore, a tantalum-based metal material is used for the upper wiring 78.
It is preferable to select the conductive material. This tantalum-based metal has a nitrogen content of 2 m in addition to simple tantalum.
ol% to 10 mol% of tantalum nitride (TaN) is used.

As the conductive material of the lower wiring 79, a mixed material containing aluminum other than the above-described (Al-Si) mixed material, as long as the specific resistance is smaller than that of the conductive material of the upper wiring 78. May be used. As such a mixed material, for example, an (Al-Si-Cu) mixed material,
(Al-Mg) mixed material, (Al-Mg-Si) mixed material, (Al-Ti) mixed material, (Al-Ti-Si) mixed material, (Al-Mn) mixed material, (Al-Mn-S)
i) Mixed material, (Al-Zn) mixed material, (Al-Zn)
-Si) mixed material, (Al-Mo) mixed material, (Al-
An alloy that is a Mo—Si) mixed material may be used.
The wiring formed of these mixed materials has the same features as the wiring formed of simple aluminum and can prevent electromigration.

Among such mixed materials, (Al—S
i) When the mixed material is subjected to an oxidation treatment by an anodic oxidation method, an insulating film formed of (Al ₂ O ₃ —SiO ₂ ) is formed. Therefore, for example, even when a crack occurs in the upper wiring 78 and the surface of the lower wiring 79 is exposed, an insulating film is formed on the lower wiring 79 during the anodic oxidation treatment for forming the insulator layer 82. Therefore, current leakage to the pixel electrode 73 due to the crack can be prevented.
Therefore, among the above-mentioned mixed materials, (Al-S
i) It is preferable to use a mixed material.

Further, the width W1 of the overlapping portion of the upper wiring 78 and the lower wiring 79 of the signal wiring 74 described above.
Is set to be 1 μm or more. The reasons are as follows. The first reason is that
The resolution capability of an apparatus used for a patterning process performed in a manufacturing process of the wiring board 67 is 1 μm or more. For example, current resist coating equipment,
The resolution limit of the stepper exposure machine and the developing device is 2
μm. For example, the resolving power of an exposure machine is caused by light used for patterning, and it is difficult to further improve it. Therefore, it is difficult to obtain a precise structure such as a wiring having a width of 1 μm or less by patterning.

The second reason is that when the width of the above-mentioned superimposed portion is 1 μm or less, the effect of reducing the resistance value of the signal wiring 74 is small. Table 1 shows the wiring resistance of each signal wiring 74 when the wiring width of the lower wiring 79 is changed.

[0086]

[Table 1]

The signal wiring 7 under each condition of Table 1 described above
The value of the wiring resistance R of No. 4 is obtained by the following equation.

[0088]

(Equation 1)

In the above equation, the length L of the wiring is 153.
6 mm. The wiring width WTa of the upper wiring 78 is 18 μm.
m. The layer thickness tTa of the upper wiring 78 is 3300 °
And The conductive material of the upper wiring 78 is tantalum. The specific resistance ρTa of tantalum is 160 μΩ · c
m. The wiring width WAl of the lower wiring 79 is 8 μm. The layer thickness tAl of the lower wiring 79 is set to 2000 °. The conductive material of the lower wiring 79 is an (Al-Si) mixed material having a specific resistance ρSi of 4.8 μΩ · cm. The width Wl of the overlapping portion of the upper wiring 78 and the lower wiring 79 in the signal wiring 74 is determined by the lower wiring 7 of the signal wiring 74.
9 is the same as the wiring width.

As shown in Table 1, when the width W1 of the overlapping portion is increased, the wiring resistance R of the signal wiring 74 is reduced. When the width W1 of the superposed portion is 1 μm or less, the wiring resistance of the signal wiring 74 becomes 20 kΩ or more, and the lower wiring 79
Is close to the state where no is formed. Therefore, it is preferable that the width of the overlapping portion W1 is 1 μm or more.

In the liquid crystal display device 61 of this embodiment, the wiring width of the upper wiring 78 is 18 μm, and the wiring width of the lower wiring 79 is 8 μm. At this time, it can be seen from Table 1 that the wiring resistance R of the signal wiring 74 is about 4 kΩ. Therefore, it can be seen that the wiring resistance is reduced to about (1/10) as compared with the case where the signal wiring 74 is formed only with the upper wiring 78 made of tantalum without forming the lower wiring 79.

In the liquid crystal display device 61 including the substrate member 67 using the signal wiring 74 formed as described above, the signal attenuation from the vicinity of the input end of the electric signal of the signal wiring 74 to the opposite end thereof is reduced. Hardly occurred. Therefore, generation of gradation in the liquid crystal display device 61 could be prevented.

A liquid crystal display device according to a second embodiment of the present invention will be described below. The liquid crystal display device of the present embodiment has the same configuration as the liquid crystal display device 61 of the first embodiment, and the same components are denoted by the same reference numerals and description thereof will be omitted.
In the liquid crystal display device of the present embodiment, the substrate member 6 on the reflection plate side is used.
The lower wiring of the seventh signal wiring 74 has a laminated structure in which a plurality of conductor layers made of different conductive materials are laminated.

The liquid crystal display device is an active matrix driving type and is a TN type reflection type liquid crystal display device. The device has a configuration in which a liquid crystal panel 63 is sandwiched between polarizing plates 64 and 65. The liquid crystal panel 63 has a configuration in which a liquid crystal layer 69 is sandwiched between a pair of substrate members 67 and 68. The lower wiring of the signal wiring 74 of the substrate member 67 on the reflector side is 2
It has a laminated structure of first and second conductor layers made of different kinds of conductive materials.

Of these conductor layers, simple aluminum (Al) is used as the conductor material of the first conductor layer. As the conductor material of the second conductor layer, a conductor material having a specific resistance smaller than that of the conductor material of the upper wiring 78 is used. In the present embodiment, simple molybdenum (Mo) is used as the conductor material of the second conductor layer. The specific resistance of molybdenum is 4.7 μΩ · c at 18 ° C.
m. The specific resistance value of simple tantalum is 14.7 μΩ · cm at 18 ° C. Therefore, the specific resistance value of simple molybdenum is smaller than the specific resistance value of simple tantalum.

The second conductor layer 112 is formed of the first conductor layer 11
1 and covers at least the upper surface of the first conductor layer. The upper wiring 78 is formed of the first and second conductor layers 11.
It is formed so as to cover the lower wiring 113 composed of 1 and 112. The lower layer of the lower electrode 81 of the MIM element 75 also has a stacked structure of the first and second conductor layers. The upper layer portion 85 of the lower electrode 81 includes the first and second conductor layers 11
It is formed so as to cover the lower layer portion 114 having a stacked structure of 1,112.

FIG. 8 is a step-by-step partial cross-sectional view in each step for explaining the manufacturing process of the substrate member 67 of the liquid crystal panel 63 of the liquid crystal display device described above. This partial sectional view has a configuration similar to the partial sectional view of FIG. Further, the manufacturing process of the substrate member has a similar process to the manufacturing process of the substrate member 67, and a detailed description of the same operation will be omitted.

First, a thin film of a conductive material of the first conductive layer 111 is formed on one surface 72 of the substrate 71. continue,
A thin film of a conductive material of the second conductive layer is formed by laminating on the thin film. As a conductor material of the first conductor layer 111,
Simple aluminum (Al) is used. As the conductor material of the second conductor layer 112, simple molybdenum (Mo)
Is used. The thickness of the thin film of the conductive material of the first conductive layer is 50 nm. The thickness of the thin film of the conductive material of the second conductive layer is 100 nm. These conductive material thin films are continuously formed by subjecting the substrate 71 to a sputtering process using, for example, an in-line type sputtering device.

Next, the lower wiring 113 and the lower electrode 11 of the lower electrode 81 are formed on the thin film of the conductive material of the second conductive layer.
A photoresist layer mask corresponding to the shape of No. 4 is formed by photolithography. The shapes of the lower layer wiring 113 and the lower layer portion 114 are the same as those of the substrate member 67 of the first embodiment.
The shape of the lower layer wiring 79 and the shape of the lower layer 86 of the lower electrode match. Subsequently, an etching process is performed on each thin film of the substrate member on which the mask is formed. In this etching process, an etching method capable of simultaneously etching a simple aluminum thin film and a simple molybdenum thin film is used. As a result, the lower wiring 1 formed by the laminated structure of the first conductor layer 111 and the second conductor layer 112 is formed.
13 and a lower layer portion 114 of the lower electrode 81 are formed.
FIG. 8A shows the substrate member formed in this manner.

Subsequently, the lower layer wiring 113 and the lower layer 11
A thin film of a conductive material such as tantalum is formed on one surface 72 of the substrate 71 on which the substrate 4 is formed, and the thin film is subjected to a patterning process. Thus, the conductor layer 106 made of tantalum is formed. The substrate member formed in this way is shown in FIG.

Subsequently, the conductor layer 106 is subjected to an oxidation treatment using an anodic oxidation method. Thereby, the conductor layer 1
06 is oxidized to form an insulator layer 82, and the remaining portion that is not oxidized becomes an upper layer portion 85 of the upper wiring 78 and the lower electrode 81. Thus, the signal wiring 74 and the lower electrode 81 are formed. The substrate member formed in this way is shown in FIG.

Subsequently, the upper electrode 83 made of, for example, titanium (Ti) and the pixel electrode 73 made of tin-indium oxide (ITO) are formed by the same method as the manufacturing method in the manufacturing process of the substrate member 67 of the first embodiment. Form. Thus, the pixel electrode 73, the signal wiring 74, and the MIM element 75 are formed on one surface of the substrate 71. FIG. 8D shows the substrate member formed in this manner.

Further, a thin film of a film material of the alignment film 76 is formed on one surface of the substrate member so as to cover each of the constituent elements 73 to 75, and the surface of the thin film is subjected to a rubbing treatment to form the alignment film 76. Form. Through such a series of processing steps, a substrate member on the reflection plate side of the liquid crystal panel 63 is formed.

The lower wiring 11 of the signal wiring 74 of this embodiment
Reference numeral 3 has a structure in which a second conductor layer made of another conductor material is laminated on a first conductor layer realized by simple aluminum. The lower layer wiring 113 includes first and second layers.
It may have a structure in which the conductor layer is laminated two or more times and a plurality of times. Further, two or more types of conductive layers of the conductive material to be stacked may be used. For example, simple aluminum (A
l), it may have a laminated structure in which conductor layers made of simple molybdenum (Mo) and simple chromium (Cr) are sequentially stacked. At this time, the uppermost layer of the lower wiring 79 is
The conductor layer in contact with the upper wiring 78 is a conductor layer other than the conductor layer formed of simple aluminum (Al).

As described above, when at least one conductor layer made of another conductor material is interposed between the conductor layer of aluminum (Al) and the upper wiring 78, the surface of the conductor layer of aluminum alone becomes The effect of hillocks and voids caused by electromigration is due to the upper wiring 7
8 can be prevented. For example, it is possible to prevent a protrusion caused by a hillock from penetrating through the upper wiring 78.

As the conductive material of the second conductive layer formed of a conductive material other than aluminum, a material having a specific resistance smaller than that of the conductive material of the upper wiring 78 is used. Table 2 shows the specific resistance at 18 ° C. of the simple metal material.

[0107]

[Table 2]

As the conductive material of the second conductive layer 112, a material having a specific resistance as small as possible is preferably used. Thus, for example, gold (Au) and silver (A
It is preferred to use g). However, gold (A
u), silver (Ag), and platinum (Pt) have a high raw material price, which causes an increase in the manufacturing cost of the substrate member 67.
Also, copper (Cu), chromium (Cr), cobalt (Co)
And cadmium (Cd) is difficult to handle. Therefore, it is preferable that molybdenum (Mo) be used as the conductor material of the second conductor layer 112.

Further, molybdenum has an excellent etching property among the above-described simple metals, and can have a high etching selectivity of the first conductor layer 111 with aluminum. For example, in the etching treatment of the thin film of simple molybdenum, by using an etching solution weaker than the etching solution for the thin film of simple aluminum, it is possible to prevent an overhang from occurring in the first conductive layer 111 of aluminum. Can be. Further, since the thin film of simple molybdenum can be etched by using the same etching solution as the etching solution of the thin film of simple aluminum, each thin film is subjected to a single wet etching treatment, and the first conductive layer and the second conductive film are etched. The conductor layers 111 and 112 can be formed simultaneously. Therefore, it is not necessary to individually etch the conductor layers 111 and 112 in the manufacturing process, and the manufacturing process is simplified.

Further, as long as the conductor material of the second conductor layer 112 has a specific resistance smaller than that of the conductor material of the upper wiring 78, various kinds of materials other than the above-described simple metal may be used. Materials can be used. For example, as the conductive material that can be used, MoSi ₂ , WSi
₂ , TaSi ₂ , TiSi ₂ , and TiN. In addition, (Al-Cu) mixed material, (Al-T
i-W) mixed material, (Sn-Cr) mixed material, (Sn-
(Cu-Cr) mixed material, (Pb-Cr) mixed material, (P
(b-Cu-Cr) mixed material and (Au-Pd-Ti) mixed material. Further, as the conductor material, a mixed material containing aluminum which is used as the conductor material of the lower wiring 79 in the first embodiment may be used.

Lower layer wiring 113 having the above-described laminated structure
It is preferable that the width W1 of the overlapping portion between the lower wiring 113 and the upper wiring 78 of the signal wiring 74 including 1 is 1 μm or more. Table 3 shows the wiring resistance R of the signal wiring 74 when the wiring width of the lower wiring 113 is changed.

[0112]

[Table 3]

The wiring resistance in Table 3 described above was obtained by calculation using the above-described equations (1) to (3). At this time,
The values of the parameters in the equations (1) to (3) are the same as the calculation of the wiring resistance R in the signal wiring 74 of the board member 67 in the first embodiment. Further, the value of the specific resistance value of the conductor material of the lower wiring 79 is replaced with the specific resistance value of a wiring having a laminated structure of simple aluminum and simple molybdenum. The specific resistance value (ρ · Mo) is 4.4 μΩ · cm.

As shown in Table 3, the width of the lower wiring 113,
That is, when the width W1 of the overlapping portion of the upper wiring 78 and the lower wiring 113 is less than 1 μm, the wiring resistance R of the signal wiring 74 is 20 kΩ or more, and the effect of reducing the resistance is small. The lower wiring 113 of this embodiment has a wiring width of 8 μm.
At this time, the wiring resistance R of the signal wiring 74 is reduced to 3.8 kΩ. Therefore, the wiring resistance can be reduced to about (1/10) compared to the case where the signal wiring 74 is formed only by the upper wiring 78 without forming the lower wiring 113.

As shown in the above-described manufacturing process, when the lower wiring 113 is formed in a laminated structure of a conductor layer of simple aluminum and single molybdenum, the first conductor layer and the second conductor layers 111 and 112 After the conductive material layers 111 and 112 are formed by laminating thin films of a conductive material, they can be collectively etched by using the same etching technique.

When the second conductor layer 112 is formed using the other conductor materials described above, the etching method of the conductor material of the second conductor layer and the etching method of the conductor material of the first conductor layer are used. May be different. At this time, the conductor layers 111 and 112 are individually formed and patterned to form the conductor layers 111 and 112.

If the etching strength of the etchant of the second conductor layer is greater than the etching strength of the etchant of the conductor material of the first conductor layer, the first conductor layer 111 may overhang. . When such an overhang occurs, the wiring resistance of the conductor layer becomes disordered,
As a whole, the wiring resistance of the signal wiring 74 does not match the design value. Therefore, the conductive material of the second conductive layer 112 can be etched with an etchant having an etching strength equal to or lower than that of the etchant of the conductive material of the first conductive layer 111. It is preferred to use a possible conductor material.

The liquid crystal display device according to the third embodiment of the present invention will be described below. The liquid crystal display device of the present embodiment has a configuration similar to that of the liquid crystal display device of the first embodiment. The liquid crystal display device 61 is a reflection type liquid crystal display device of a TN type which is of an active matrix drive system. The liquid crystal display device has a configuration in which a liquid crystal panel 63 is sandwiched between polarizing plates 64 and 65. The liquid crystal panel 63 has a configuration in which the liquid crystal layer 69 is sandwiched between the substrate member 116 and the substrate member 68.

FIG. 9 is a partial plan view showing the detailed structure of the substrate member 116. The board member 116 has a configuration similar to that of the board member 67 of the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted. The substrate member 116 has a pixel electrode 73, a signal wiring 74, and a MIM element 75 arranged in a predetermined arrangement on one surface 72 of an insulating substrate 71 having a light-transmitting property.
75, and an alignment film 76 is formed. The signal wiring 74 has a laminated structure in which an upper wiring 78 and a lower wiring 79 are overlapped.

The MIM element 75 has a structure in which a lower electrode 117, an insulator layer 82, and an upper electrode 83 are stacked in this order from the bottom. The lower electrode 117 is formed integrally with only the upper wiring 78 of the signal wiring 74 and is electrically connected. Therefore, unlike the lower electrode 81 of the first embodiment, the lower electrode 117 does not include the lower layer 86 made of the same conductive material as the lower wiring 79 of the signal wiring 74. The lower electrode 117 is formed only of the same conductive material as the upper wiring 78.

In the MIM element 75 of the first embodiment, when a pinhole is formed in the conductor layer 106 to be the upper layer 85 of the lower electrode 81 in the manufacturing process, the insulator layer 82 In some cases, impurities may be mixed in from the lower layer portion 86. Since the lower electrode 117 of the MIM element 75 of the present embodiment is formed of only tantalum (Ta) alone, even if a pinhole is formed in the conductor layer that is a material of the lower electrode 117, the lower electrode 117 is insulated during the anodic oxidation process. Body layer 82
Can be prevented from being mixed with impurities.

In the present embodiment, lower wiring 79 of signal wiring 74 is realized by, for example, a mixed material of aluminum. The lower wiring 79 is made of a simple aluminum (A
It may have a laminated structure of l) and another conductive material.

The liquid crystal display devices according to the first to third embodiments are reflection type liquid crystal display devices. The liquid crystal display device of this embodiment can be used as a transmissive liquid crystal display device by removing the reflector attached to the polarizing plate 65 and providing a light source instead of the reflector. Such MIM
An active matrix driving type liquid crystal display device using the element 75 as a switching element is a thin film transistor (TF
The aperture ratio is larger than that of a liquid crystal display device using T) as a switching element. Therefore, a brighter display can be realized as the transmissive and reflective liquid crystal display devices.

Although the liquid crystal display devices of the first to third embodiments are TN type liquid crystal display devices,
Pixel electrode 73, signal wiring 74, and MIM of this embodiment
The element 75 can also be used as a component of a GH liquid crystal display device.

FIG. 10 is a partial sectional view showing the structure of a phase-change GH type liquid crystal display device 131 according to a fourth embodiment of the present invention. The device 131 has a so-called H-VGA pixel array in which (480 × 320) pixels are arranged in a matrix, and performs color display. In a GH type liquid crystal display device,
Display is performed utilizing the anisotropy of the absorption coefficient of the dichroic dye added to the liquid crystal to be enclosed.

The device 131 comprises a pair of substrate members 132, 1
Reference numeral 33 denotes a configuration in which a liquid crystal layer 134 made of a cholesteric liquid crystal to which a p-type dye is added is sandwiched. Substrate member 13
Except for the numbers, the components 2 and 133 have a configuration similar to the board members 67 and 68 of the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted. .

FIG. 11 is a partial plan view showing a detailed structure of one substrate member 132 of liquid crystal display device 131. Hereinafter, FIG. 10 and FIG. 11 will be described together.

On one surface 72 of the light-transmitting insulating substrate 71, the same number of signal lines 74 as the number of pixel columns are parallel to each other at predetermined intervals along the horizontal direction H. , The longitudinal direction of each wiring is arranged in parallel with the vertical direction V. The signal wiring 74 includes an upper wiring 78 and a lower wiring 79.
Are laminated. Each of the signal wirings is provided with the same number of MIM elements 75 as the number of pixel rows, one by one in the pixel region 96. Signal wiring 74 and MI
On the M element 75, an organic insulating layer 142 is formed so as to cover the components 74 and 75.

The pixel electrodes 75a are superposed on the organic insulating layer 142, are electrically insulated from the signal wiring 74, and are arranged in a matrix. The pixel electrode 75a and the lower electrode 83 of the MIM element 75 are electrically connected through a through hole 145 provided in the organic insulating layer 142. Further, the substrate 7
1 on one surface 72, each component 73, 74, 75a
Is formed so that the alignment film 76 is subjected to an alignment process in a predetermined alignment direction.

In the GH type liquid crystal display device, the pixel electrode 75
a also serves as a reflector. The pixel electrode 75a is manufactured by forming a thin film of a conductive material having a high reflectance, such as a metal material, on one surface 146 of the organic insulating layer 142 and performing a patterning process on the thin film. Organic insulating layer 142
One surface 146 is formed with irregularities indicated by solid and large circles in the partial plan view of FIG. Since the pixel electrode 75a is formed from a conductive thin film formed on one surface 146 of the organic insulating layer 142, it has similar irregularities. Thereby, the light reflection efficiency of the electrode 75a is improved. Therefore, one surface of the pixel electrode 75a is a diffuse reflection surface having a high reflectance, and the display brightness and contrast ratio of the device 131 are improved.

FIG. 12 is a partial plan view showing the detailed configuration of the other substrate member 133 of the liquid crystal display device 131. Hereinafter, FIG. 10 and FIG. 12 will be described together.

On the other hand, the substrate member 133 is provided with a band-shaped counter electrode 93 on one surface 92 of the translucent insulating substrate 91 on the liquid crystal layer 134 side, as viewed in the normal direction U.
Are formed along a direction orthogonal to the direction in which the signal wiring 74 extends. One surface 92 of substrate 91 and counter electrode 93
A color filter 153, which is a color filter having a different color for each pixel and arranged in the same arrangement state as the pixel arrangement of the pixels, is interposed therebetween. The one surface is formed so as to cover the components 93 and 153, and is covered with an alignment film 94 that has been subjected to an alignment process in a predetermined alignment direction.

Referring again to FIG. In the GH type liquid crystal display device, a dichroic dye is mixed in the liquid crystal layer 134.
The dye molecule of the dichroic dye has, for example, a rod-like structure,
The dye molecules are aligned so that the major axis of the dye molecule is parallel to the liquid crystal molecular axis. Further, the p-type dichroic dye has an absorption axis substantially parallel to the dye molecular axis, strongly absorbs light polarized in a direction parallel to the molecular axis, and almost completely absorbs light polarized in a direction perpendicular to the molecular axis. Has absorption characteristics that do not absorb.

Each pixel of the liquid crystal display device 131 has a colored state that transmits light and a colorless state that blocks light according to the presence or absence of an electric field generated in the liquid crystal layer 134 sandwiched between the electrodes 75a and 93 of the pixel. Is switched to The presence or absence of the electric field is controlled by switching whether or not a predetermined voltage is applied between the electrodes 75a and 93.

When no electric field is generated in the liquid crystal layer 134 of the pixel, the liquid crystal molecules and the dye molecules are irregularly arranged in the liquid crystal layer 134 only on one surface 72, 92 of one of the substrates 71, 91. Therefore, the light incident on the liquid crystal layer is absorbed by the dye molecules and becomes a colorless state in which the light is blocked. When an electric field is generated in the liquid crystal layer, the molecular axes are arranged along the direction of the electric field so as to be substantially perpendicular to one surface 72, 92 of the substrates 71, 91. Therefore, light that has entered the liquid crystal layer 134 from the other substrate member 133 side passes through the liquid crystal layer 134, is reflected on the surface of the pixel electrode 75a also serving as a reflector, and passes through the liquid crystal layer 134 and the other substrate member 133 again. And is emitted. As a result, the pixel enters a colored state in which light is transmitted.

In the TN type liquid crystal display device, only light polarized in a direction substantially parallel to the transmission axis of the polarizing plate on the substrate member side is incident on the liquid crystal layer, and the remaining light is absorbed by the polarizing plate. Therefore, in the reflection type liquid crystal display device of the TN mode, the light reflectance generally drops to 50% or less. As a result, the brightness of the display screen may be reduced to be lower than the desired brightness. Since a polarizing plate is not used in a phase change GH type liquid crystal display device, almost 100% of light incident on the pixel can be emitted from a pixel that performs color display. Therefore, a brighter display can be realized.

Further, the signal wiring 74 having the above-described configuration is not limited to a substrate member of a liquid crystal display device, and can be used as a signal wiring of a substrate member used for other purposes. In particular, the substrate member having the signal wiring 74 and the MIM element 75 having such a structure is preferably used for a substrate member having a structure in which the wiring resistance of the signal wiring 74 is increased. Examples of the wiring structure having a high wiring resistance include a structure having a small wiring width, a structure having a small wiring thickness, and a structure having a long wiring length. In a wiring having such a wiring structure, it is conceivable that an input electric signal is attenuated from the signal input end of the wiring to the opposite end. The signal wiring having the above-described structure can reduce the occurrence of the attenuation.

[0138]

As described above, according to the present invention, a plurality of individual electrodes are connected to the signal wiring of the wiring board via the two-terminal switching element. The signal wiring has a stacked structure of a first wiring made of a mixed material containing aluminum and a second wiring made of a conductive material having a higher specific resistance than the aluminum mixed material.

As a result, the wiring resistance can be reduced as compared with the signal wiring formed in the same shape using only the conductive material of the second wiring. Therefore, the same electric signal can be given to each individual electrode while preventing attenuation and distortion of the electric signal transmitted through the signal wiring. Also,
The first wiring can be prevented from being changed in shape due to so-called electromigration, and the first wiring can be prevented from being damaged in the manufacturing process of the wiring board. Further, the signal wiring is realized by using an aluminum mixed material which is more suitable for the wiring material than the other materials and is inexpensive and easy to process, so that the manufacturing cost of the wiring board can be reduced. Further, when the wiring substrate is used as a substrate member of a liquid crystal display device, the aperture ratio of the device can be improved and a device with a bright display screen can be realized.

According to the present invention, a plurality of individual electrodes are connected to the signal wiring of the wiring board via the two-terminal switching element. The signal wiring includes a first wiring and a second wiring made of a conductive material having a higher specific resistance value than aluminum.
It has a laminated structure with wiring. The first wiring includes a first conductive layer made of simple aluminum and a second conductive layer made of a conductive material other than simple aluminum, and the outermost layer in contact with the second wiring is the second conductive layer. It has a laminated structure of a plurality of conductor layers laminated so as to form conductor layers. The specific resistance value of the conductive material of the second conductive layer of the first wiring is the second resistance.
It is smaller than the specific resistance value of the conductor material of the wiring.

Thus, similarly to the above-described signal wiring of the wiring board, the wiring resistance of the wiring can be reduced, and the attenuation and distortion of the electric signal transmitted through the signal wiring can be prevented. Further, it is possible to prevent the influence of the shape change due to the electromigration in the first conductive layer from being applied to the second wiring, and to prevent the influence from being applied to the second wiring. It is possible to prevent the first wiring from being damaged in the manufacturing process of the wiring board. Further, when the wiring substrate is used as a substrate member of a liquid crystal display device, an aperture ratio of the device can be improved, and a device that performs bright display can be realized.

According to the present invention, the width of the overlapping portion of the first and second wirings in the signal wiring is 1 μm or more.
Thus, each wiring can be formed by a general patterning process. Further, even when the signal wiring is made as thin as possible, the specific resistance value of the signal wiring can be made lower than that of the wiring made of only the conductive material of the second wiring.

Further, according to the present invention, the second wiring of the signal wiring is realized by a tantalum-based metal. Therefore, the second wiring and the lower electrode of the MIM element can be integrally formed at the same time. Further, when forming the insulator layer of the MIM element, an insulating film for insulating the second wiring can be formed at the same time. Therefore, it is possible to prevent the electric signal from leaking directly from the signal wiring to the individual electrode.

[Brief description of the drawings]

FIG. 1 is a liquid crystal display device 61 according to a first embodiment of the present invention.
It is sectional drawing which shows a structure of.

FIG. 2 is a front view of the liquid crystal display device 61.

FIG. 3 is a plan view showing a detailed configuration of a substrate member 67 on a reflection plate side of a liquid crystal panel 63 of the liquid crystal display device 61.

FIG. 4 is a cross-sectional view of the substrate member BB.

FIG. 5 shows a polarizing plate 6 of a liquid crystal panel 63 of a liquid crystal display device 61.
It is a top view which shows the detailed structure of the board member 68 of the 4 side.

FIG. 6 is a step-wise partial cross-sectional view for explaining a manufacturing process of the substrate member 67.

FIG. 7 is a step-by-step partial cross-sectional view for explaining a manufacturing process of a substrate member on the reflection plate side of the liquid crystal panel of the liquid crystal display device of the first related art as a comparative example.

FIG. 8 is a step-by-step partial cross-sectional view for explaining a manufacturing process of a substrate member 67 on the reflection plate side of the liquid crystal panel 63 of the liquid crystal display device according to the second embodiment of the present invention.

FIG. 9 is a partial plan view illustrating a detailed configuration of a substrate member 67 on a reflection plate side of a liquid crystal panel 63 of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 10 is a liquid crystal display device 1 according to a fourth embodiment of the present invention.
It is sectional drawing which shows the structure of 31.

FIG. 11 is a partial plan view showing a detailed configuration of a substrate member 132 of the liquid crystal display device 131.

FIG. 12 is a partial plan view showing a detailed configuration of a substrate member 133 on a display screen side of the liquid crystal display device 131.

FIG. 13 is a partial plan view for describing in detail a configuration of one substrate member 1 on a reflector side using an MIM element as a switching element in a liquid crystal panel of a liquid crystal display device according to a first conventional technique.

FIG. 14 is a partial plan view for explaining in detail a configuration of one substrate member 11 on a polarizing plate side using a TFT as a switching element in a liquid crystal panel of a liquid crystal display device according to a first conventional technique.

FIG. 15 is a cross-sectional view for explaining a detailed configuration of signal wirings 6 and 16 of substrate members 1 and 11;

FIG. 16 is a partial cross-sectional view showing a hillock convex portion 25 generated in the lower layer wiring 22 of the signal lines 6 and 16 in the first prior art liquid crystal display device, and one including the lower layer wiring 22 in which the convex portion 25 is formed. FIG. 3 is a partial cross-sectional view showing a state where the substrate members 1 and 11 have been subjected to an etching process.

FIG. 17 shows a concave portion 2 of a void generated in the lower wiring 22 of the signal wirings 6 and 16 in the first prior art liquid crystal display device.
6 and a partial cross-sectional view showing a state in which one of the substrate members 1 and 11 including the lower layer wiring 22 having the concave portion 26 is subjected to an etching process.

[Explanation of symbols]

 61, 131 Liquid crystal display device 67, 68; 116; 132, 133 Substrate member 71 Substrate 73 Pixel electrode 74 Signal wiring 75 MIM element 78 Upper wiring 79, 113 Lower wiring 111 First conductive layer 112 Second conductive layer

Claims (4)

[Claims] A plurality of electrodes arranged on an insulating substrate; a plurality of signal wirings arranged on the substrate and supplied with an electric signal to be supplied to each electrode; and a plurality of signal wirings provided on the signal wiring. A wiring board having a two-terminal switching element including a plurality of two-terminal switching elements that individually supply / cut off an electric signal to each electrode,
Each signal wiring has a first wiring having a predetermined width, and a second wiring having a width larger than the first wiring and being formed on the first wiring so as to overlap with the first wiring.
Wherein the first wiring is made of a conductive material containing aluminum and having a specific resistance smaller than the specific resistance of the conductive material forming the second wiring. A wiring board having the same. 2. A plurality of electrodes arranged on an insulating substrate; a plurality of signal lines arranged on the substrate and supplied with an electric signal to be supplied to each electrode; and a plurality of signal lines provided on the signal line. A wiring board having a two-terminal switching element having a plurality of two-terminal switching elements for individually supplying / cutting an electric signal to / from each electrode, wherein each of the signal wirings includes a first wiring having a predetermined width and a first wiring having a predetermined width. And a second wiring having a width larger than that of the first wiring and being formed on the first wiring so as to overlap with the first wiring. The first wiring has a first conductor layer made of aluminum, The second wiring includes a second conductive layer made of a conductive material having a specific resistance smaller than that of the conductive material constituting the second wiring, wherein the second conductive layer includes the first conductive layer and the second wiring. And is formed so as to be interposed between the second wiring and the second wiring. Resistivity of the material, the wiring board having a two-terminal switching element being greater than the resistivity of aluminum. 3. The wiring board having a two-terminal switching element according to claim 1, wherein a width of an overlapping portion of the first wiring and the second wiring is at least 1 μm or more. 4. The two-terminal switching element includes: a first electrode electrically connected to the signal wiring and integrally formed; a second electrode electrically connected to the pixel electrode; 3. A two-terminal non-linear element formed by laminating an insulator layer interposed between second electrodes, wherein the conductor material of the second wiring contains at least tantalum. A wiring board having the two-terminal switching element according to any one of the preceding claims.