JP3482825B2 - Color filter substrate for reflective liquid crystal display - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal display device,
The present invention relates to an output display device such as an EL (electro luminescence) display device, an input / output display device for directly inputting from a display screen, or an electrode substrate used for a solar cell or the like, particularly for a reflective liquid crystal display device. Of color filter substrate.

[0002]

2. Description of the Related Art In general, a liquid crystal display device is mainly composed of a pair of electrode plates on which electrodes are arranged and a liquid crystal substance enclosed between the electrode plates. By applying a voltage between the electrodes, the alignment state of the liquid crystal substance is changed to control the plane of polarization of the light passing through the liquid crystal substance, and the polarizing film controls the transmission and non-transmission of the liquid crystal for screen display. It is a thing.

The liquid crystal display device is generally a transmissive liquid crystal display device having a light source (lamp) as a backlight. However, since these transmissive liquid crystal display devices consume a large amount of power due to a backlight lamp and have a short operating time when driven by a battery, they are not able to take full advantage of the liquid crystal display device's inherent portable characteristics. There was a problem. For this reason, in recent years, development of a reflection type liquid crystal display device that utilizes external light (that is, no built-in backlight lamp) has become active.

As a reflective liquid crystal display device, for example, as shown in the schematic view of FIG. 3, a structure in which a reflective film 31 and a color filter 32 are sequentially laminated on the surface side of a rear substrate 30 such as glass facing the liquid crystal 39. There are many proposals using the color filter substrate 2. The color filter 32
Is a plurality of light-transmissive pixels (hereinafter, simply referred to as pixels) colored in R (red), G (green), B (blue), etc., formed in accordance with a predetermined pattern. Further, the reflection film 31 may be used as the above-mentioned reflection electrode which also serves as an electrode.

Conventionally, an aluminum thin film is often used as the reflection film 31 shown in FIG. But,
Aluminum has a problem that it is easily corroded by water or a base, and as a reflective electrode, it has a low light reflectance and is easily electrically disconnected. Further, aluminum has a characteristic problem of low light reflectance.

For this reason, it has been proposed to use silver as a material for the reflective film. It can be said that silver is superior to aluminum in the above points, that is, in terms of corrosion resistance and light reflectance (for example, silver has a light reflectance of about 10% as compared to aluminum. Excellent). However, silver has a drawback that it has a low adhesion to a substrate such as glass or plastic, and when it is formed on the substrate as a silver thin film, it is easily peeled off from the substrate. Further, when a silver thin film is formed on a substrate with high-purity silver, the high-purity silver thin film easily aggregates due to the influence of heat and oxygen, and the heat treatment causes the silver thin film to become cloudy. There is also the problem that it looks like.

The present inventors have made up for the above-mentioned drawbacks of silver,
Japanese Patent Application No. Hei 7 (1999) describes a technology for providing silver with high reflectance at a practical level.
It has been proposed in No. -88798. In this technique, as shown in FIG. 4 in which a portion B surrounded by a dotted line in FIG. 3 is enlarged, a reflection film 41 is sandwiched between a mixed oxide thin film 45 and a mixed oxide thin film 47 and a silver alloy thin film 46. Since it has a three-layer structure and the surface of the silver alloy thin film is covered with the mixed oxide,
This has the advantage that the silver alloy thin film is protected.

[0008]

The brightness of "white" at the time of screen display is one of the most important points in the display performance of a reflective liquid crystal display device. In order to make "white" brighter, the liquid crystal display mode is set such that when no voltage is applied, the light incident on the display device passes through the liquid crystal substance,
The so-called normally white mode in which the transmitted light is reflected by the reflective film 31 and the display screen looks "white", and the reflective film 31 that reflects light is made to be a solid surface like a mirror (that is, all are electrically It is desirable to form them in a state in which they are continuously connected. At this time, the aperture ratio of "white" is defined as 100%.

Further, in recent years, liquid crystal display devices are required to have high display quality. Therefore, in the reflection type liquid crystal display device, there is an increasing demand for improving the durability of the reflective film. That is, when the resistance of the reflective film is poor, defects (such as spots) occur in the reflective film due to moisture (humidity) in the surrounding atmosphere, and display defects and disconnection of electrodes occur, which lowers the display quality. Is.

However, in the technique proposed by the present inventor, since the silver alloy thin film, which is a reflective film, is used as an electrode, for example, since the patterning is performed in stripes, the number of light reflecting portions is reduced and the "white" aperture ratio is 100. % Up to 85 ~
The aperture ratio was 90%, and the brightness of "white" was inferior. Also, in terms of resistance, it cannot be said that the performance required in recent years is sufficiently satisfied, and defects such as spots occur at the end of the reflective film, and display defects and electrode disconnection occur. It is a thing.

The present invention has been made in view of the above problems, and its problem is that at least an adhesive layer, a silver alloy thin film, and one or more color filters are provided on a substrate. It is an object of the present invention to provide a color filter substrate for a reflective liquid crystal display device, which is capable of displaying a bright screen on a color filter substrate for a reflective liquid crystal display device, which is sequentially stacked, and which has high resistance and is less likely to cause a display defect.

[0012]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems. as a result,
The focus is on the edges of the color filter substrate. This is because, in the conventional color filter substrate, as shown in FIG. 4 described above, the silver alloy thin film 46 which is a component of the reflective film 41 is exposed from the end surface of the color filter substrate. Therefore, in the state shown in FIG. 4, due to the moisture (humidity) in the surrounding atmosphere, the mixed oxide thin films 47 and 45 are formed.
The present inventors have found that the interfaces 48 and 49 with the silver alloy thin film 46 are eroded, resulting in poor adhesion between these layers. In addition, when alkali (alkali metal element) adheres to and remains on the color filter substrate due to human contact or insufficient washing with water after the alkali cleaning in the color filter substrate manufacturing process, the above-mentioned poor adhesion between the layers. The present inventors have also found that is more likely to occur.

The present inventors are studying the mechanism of the reaction in which the interface between the mixed oxide thin films 47 and 45 and the silver alloy thin film 46 is eroded. I haven't gone. However, the approximate situation in which silver is oxidized at the interfaces 48 and 49 and at the same time the mixed oxide is reduced to form a hydrate is clear, as will be described later. .

The reaction at this interface proceeds from the pattern end of the silver alloy thin film 46 exposed to the outside air.
In addition, the reaction is rather slow and does not proceed rapidly, but as time passes, it may reach the seal part that seals the liquid crystal substance. In that case, the sealing strength of the liquid crystal seal decreases. However, this is not preferable for the operation of the liquid crystal display device.

From the above points, the present inventors have made a liquid crystal cell into a liquid crystal display device, that is, when a liquid crystal substance is enclosed between a pair of electrode plates provided with electrodes, a pattern of a reflective film is formed. The present invention proposes a color filter substrate for a reflective liquid crystal display device in which the edge (end) is not exposed from the end face of the substrate. Further, the invention according to claim 1 will be described below. The present inventors formed a reflective film using a soda glass containing an alkali metal element as a substrate and a non-alkali glass containing no alkali metal element (for example, 7059 material manufactured by Corning Incorporated) as a substrate. It has been empirically found that the reflection film having a substrate made of soda glass containing an alkali metal element has lower moisture resistance. As a result, the present inventors presume that the resistance of the reflective film is affected by the alkali metal element contained in the substrate. The present inventors conducted the following test to confirm this assumption. First, a soda glass containing an alkali metal element is used as a glass substrate, and a reflective film 11 having a three-layer structure is formed on the glass substrate as shown in FIG. 11, and a thin film X-ray showing the crystalline state of the reflective film 11 is formed. The diffraction data 71 is shown in FIG.
Shown in. The reflection film 11 is formed by a sputtering method as in the later-described (Example), and has a three-layer structure in which the silver oxide thin film 26 is sandwiched between the mixed oxide thin film 25 and the mixed oxide thin film 27. Further, the mixed oxide thin films 25 and 27 are
Cerium oxide, tin oxide, and titanium oxide are added to indium oxide as a base material, and the composition is 32 at% (atomic percent) of cerium and 1 to 1 of tin and titanium in terms of metal elements excluding oxygen. It was 0.5 at% (atomic percent). In addition, silver alloy, silver 1 gold 1
At% (atomic percent) and copper are added at 0.5 at% (atomic percent), respectively. Then, the substrate 50 having the reflective film 11 formed thereon was subjected to a pressure cooker test (PCT) of leaving it in an atmosphere of a temperature of 120 ° C., a humidity of 100%, and a pressure of 2 atm for 10 hours. FIG. 7 shows thin film X-ray diffraction data 72 showing the crystalline state of the reflective film 11 of FIG. In addition, in FIG. 7 and the graph of FIG. 8 described later, the horizontal axis represents the diffraction angle 2θ (°) of the X-ray,
The vertical axis represents the diffraction intensity (CPS). As can be seen from FIG. 7, in the thin film X-ray diffraction data 71 showing the crystalline state of the reflective film before PCT, a gentle peak can be observed, but no prominent peak is observed, indicating that crystallization progresses in the reflective film. Cannot be said. On the other hand, in the thin film X-ray diffraction data 72 showing the crystalline state of the reflective film after PCT, it is obvious that the peak 73 (dotted line part in FIG. 7) is around 2θ of 28 ° with θ as the diffraction angle. Appeared, and it was found that some kind of crystalline substance was formed on the reflective film. Therefore, the inventors of the present invention assumed an alkali metal element as a crystal substance in which a remarkable peak 73 was generated, and further conducted the following test as a confirmation test. That is, the indium nitrate powder was heat-treated at a temperature of 400 ° C. for 3 hours to form indium oxide (In 2 O 3) thin film X-ray diffraction data 81, and indium nitrate and sodium hydroxide (NaOH) were mixed. The thin film X-ray diffraction data 82 was obtained after the mixture was heat-treated at 400 ° C. for 3 hours as described above. Figure 8 shows thin film X-ray diffraction data obtained from indium oxide (In2 O3) alone.
81, indium nitrate and sodium hydroxide (NaOH)
The thin film X-ray diffraction data 82 obtained from the mixture of As is clear from FIG. 8, the mixture of indium nitrate and sodium hydroxide (NaOH) has a 2θ of 28.
A prominent peak 83 (indicated by a dotted line in FIG. 8) appears in the vicinity of 0 °, which is the thin film X-ray diffraction data shown in FIG. 7.
Consistent with 72 prominent peaks 73. From this, it is judged that the remarkable peak of the thin film X-ray diffraction data 72 of FIG. 7 appeared due to the crystallization of the Na (sodium) compound. From the above tests, the present inventors have found that the substrate supporting the reflection film contains an alkali metal element (for example, the substrate is soda glass containing Na (sodium) which is an alkali metal element). ), The alkali metal element begins to melt from the substrate under moisture (humidity) in the surrounding atmosphere, and the alkali metal element diffuses into the reflective film. Furthermore, when the alkali metal element diffuses into the reflection film, the alkali metal element causes migration to the silver alloy thin film that constitutes the reflection film, and as a result, destroys the reflection film, causing defects such as spots and peeling. The present inventors have found out. For this reason, the inventors of the present invention have found that if the substrate supporting the reflective film contains almost no alkali metal element, more preferably no alkali metal element at all, even if there is moisture (humidity) in the atmosphere around the substrate. The present invention is based on the idea that defects such as spots do not occur in the reflective film, that is, the moisture resistance of the reflective film is improved. As described further below
In addition, when the silver thin film and the metal thin film are in contact with each other,
And the presence of alkali metal elements have a very bad effect on the reflective film.
It gives a sound. Therefore, the deterioration of the reflective film is suppressed.
One of the ways to get it is to expose the reflective film
Overcoat layer with transparent resin, or
Is ITO (a mixed oxide of indium oxide and tin oxide)
It is preferable to cover the reflective film with a transparent electrode formed in
Can be said.

That is, the invention according to claim 1 is a color filter substrate for a reflection type liquid crystal display device, in which at least an adhesive layer, a silver alloy thin film, and a color filter having one or more surfaces are sequentially laminated on the substrate. In each of the color filters for each surface, the silver alloy thin film has one electrically independent pattern, and when the liquid crystal cell is formed into a liquid crystal display device, the silver alloy thin film pattern is formed from the end surface of the substrate. Not exposed and transparent on the color filter
Less resin overcoat layer or transparent electrode
Both are laminated to cover the entire surface of the above silver alloy thin film.
In addition, the surface of the substrate or the substrate itself is made of a material that does not substantially contain an alkali metal element. For example, as the substrate used in the present invention, use alkali-free glass containing no alkali metal element such as 7059 material or 1737 material manufactured by Corning Co., Ltd. rather than soda glass containing alkali metal element such as Na (sodium). Is preferred.

As described above, in the color filter substrate of the present invention, the color filter formed on the substrate may be provided on one side or may be provided on multiple sides in consideration of productivity and the like. When multiple color filters are attached on the substrate, the size of the color filters is approximately the same as that of the color filters so as to face each color filter, and one electrically connected pattern is formed (for example, the entire surface is made solid). ) The same number of silver alloy thin films as the color filters are formed on the substrate.

In the case of a color filter substrate having multiple color filters attached, the TFT is similar to the color filter.
Substrates formed by attaching (thin film transistor) matrices on multiple surfaces are stacked so that individual color filters and TFT (thin film transistor) matrices face each other, and then liquid crystal is sealed between these substrates. After encapsulating and sealing the liquid crystal, the liquid crystal cell is obtained by cutting and dividing so that the color filter and the TFT (thin film transistor) matrix facing each other become a set.

At the time of this cutting and dividing, as shown in FIG. 1 described later, the edge of the effective pattern of the silver alloy thin film.
Is not exposed from the fractured surface of the substrate is the main object of the present invention. The above-mentioned "effective pattern" is a color filter pattern, that is, a solid pattern, for example, which is made of a silver alloy thin film and faces the screen display portion. That is, at the time of manufacturing the color filter substrate, for example, alignment marks 15, 15 'for alignment, accuracy patterns called vernier formed for the purpose of manufacturing, or a pattern such as a cutting line is as described above. It can be said that it may be exposed from the fracture surface of the substrate as long as it is electrically independent of the "effective pattern". Next, the color filter substrate of the present invention can be used as a semi-transmissive color filter substrate having a light source on the back surface of the substrate by reducing the thickness of the silver alloy thin film. However, in this case, since the thickness of the silver alloy thin film is small, the portion where the pixel is not formed (non-opening portion)
Then, the light from the back surface of the substrate is transmitted without being blocked by the silver alloy thin film. Because of this, in a dark room,
When the liquid crystal display device incorporating the semi-transmissive color filter substrate is used, the transmitted light from the non-aperture portion is conspicuous and the display quality of the liquid crystal display device is deteriorated. Therefore, when the color filter substrate of the present invention is used as a semi-transmissive color filter substrate, the present inventors eliminate the transmitted light in the non-opening portion and ensure the color purity as much as possible. It is proposed to increase the film thickness of and to provide an opening in the silver alloy thin film portion facing the central region of each pixel. Therefore, the invention according to claim 2 is characterized by being a silver alloy thin film capable of transmitting light from the back surface of the substrate by forming an opening in a part of the silver alloy thin film. In addition, according to the use environment of the liquid crystal display device incorporating the color filter substrate, when the color filter substrate is manufactured as a reflective type or a transmissive type, it can be easily adjusted by appropriately adjusting the size and position of the aperture. It is possible to change to a reflective type or a transmissive type.

As described above, it is preferable to use a silver thin film or a silver alloy thin film as the reflective film in terms of light reflectance. However, these silver-based thin films do not have sufficient adhesion to substrates made of glass or plastic. Therefore, in order to improve the adhesion of the silver alloy thin film to the substrate, the present inventors previously formed a metal thin film or a metal oxide thin film having an adhesive force on the substrate on the substrate, and then, ,
They have found that it is good to form a silver alloy thin film.

That is, the invention according to claim 3 is characterized in that the adhesive layer is an adhesive layer selected from at least one of a metal thin film and a metal oxide thin film.

The adhesive layer may be formed of aluminum, an aluminum alloy, a nickel-chromium alloy, a magnesium alloy, a refractory metal such as titanium or tantalum, or a metal thin film of these alloys. Alternatively, the adhesive layer may be formed as a thin film from a metal oxide such as indium oxide, tin oxide, aluminum oxide, zinc oxide, or titanium oxide, or a mixture of these metal oxides. Further, it may be formed of metal nitride.

The silver thin film or the silver alloy thin film generally has the drawbacks that silver sulfides are formed on the surface to cause discoloration, and that they are soft and easily scratched. In order to compensate for this, it is desirable to form a transparent metal oxide film on the silver alloy thin film to protect the silver alloy thin film.

Therefore, the invention according to claim 4 is characterized in that a metal oxide thin film is inserted between the color filter and the silver alloy thin film.

The metal oxide thin film formed on the silver alloy thin film is not particularly limited as long as it is transparent and has a small amount of ionic eluate. For example, Periodic Table of Elements 4a
Group, 5a group, 3b group, 4b group, or Zn (zinc)
The above oxide or a mixed oxide of these oxides may be used. Among them, mixed oxides obtained by adding oxides having a high refractive index such as cerium oxide and titanium oxide to oxides such as indium oxide, tin oxide and zinc oxide are particularly preferable.

The metal oxide used in the present invention has no crystal grain and is in an amorphous state in order to avoid grain boundary diffusion of silver by the metal oxide thin film (silver easily moves on the grain boundary and surface of the metal oxide). It is preferably a metal oxide thin film.

In addition, the inventors of the present invention have found that, in the structure in which the silver thin film and the metal oxide thin film are in contact with each other, as a result of long-term storage or a humidity test (under high temperature and high humidity conditions), the silver thin film and the metal oxide film are oxidized. It was found that the interface with the thin film tends to be weakened and peeled off easily. As a result, the present inventors have found that in the presence of water (humidity) and also of an alkali metal element, silver oxidizes (emits electrons) at the interface between silver and an oxide, which causes a metal reaction with complicated reactions. It was judged that the oxide was clearly affected. Therefore, it is important to suppress the electron emission of silver in order to improve the resistance of the reflective film. From this viewpoint, it is effective to use a silver alloy thin film in which a metal having a work function higher than that of silver is added to silver. The present inventors have found that

AGNE PERIODIC TABLE
According to the Periodic Table of Elements, the work function of silver is 4.28 eV, and similarly, copper is 4.47 eV, gold is 4.58 eV, nickel is 4.84 eV, palladium is 4.82 eV, and platinum (platinum) is used.
Is 5.29 eV, and it is preferable to add a metal having a work function higher than silver to silver. However, when the total amount of the metals added to these silver exceeds 5 at% (atomic percent), the light reflectance of the silver alloy thin film is conspicuously lowered, and gold,
Noble metals such as platinum and palladium are expensive and have a large cost impact, so the total amount of metals added to silver is 5 at.
% (Atomic percent) or less is desirable.

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

In the present invention, a transparent electrode made of ITO (a mixed oxide of tin oxide and indium oxide) may be laminated as a constituent element of the color filter substrate.
This transparent electrode may be formed into a predetermined pattern by a known means such as a photolithography method after forming a solid film on the entire surface by a sparring method, an evaporation method or the like, or using a mask sputtering method, It may be formed in a predetermined pattern shape. In addition, in the color filter substrate for the liquid crystal display device using the horizontal electric field system called IPS, the above-mentioned transparent electrode may not be formed. It is also possible to use a reflective film as the common-side drive electrode instead of the transparent electrode. At this time,
The transparent electrode may be omitted by forming a thin color filter or overcoat.

The substrate that can be used in the present invention is not limited to a transparent substrate, and may be a substrate colored in white or another color. Further, an electric circuit, a solar cell, a silicon wafer, semiconductor elements such as amorphous silicon or polysilicon, and MIM (diode element) may be formed on the substrate itself. Further, an optical functional film such as a polarizing plate including elliptically polarized light, a λ / 4 wavelength plate, a retardation film, a light scattering film, a microlens, a diffraction grating, or a hologram is indirectly or directly formed on the reflective film. It doesn't matter.

[0047]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment of the present invention will be described in detail. Example 1 As shown in FIG. 1, the color filter substrate 1 for a reflective liquid crystal display device according to Example 1 has a thickness of
0.7mm non-alkali glass substrate 10 (Corning, 1
737 material), a reflective film 11, a color filter 12 formed by a known pigment dispersion method, an overcoat layer 13 made of an acrylic resin or the like, and a transparent electrode 14 having a thickness of 140 nm. Its main part is composed. Here, based on the gist of the present invention, the reflective film 11 is formed so as to be solid over the entire surface so as to cover at least the formation region of the color filter 12 and to be inside the end portion of the substrate 10.
It should be noted that the reflective film 11 is provided near the edge of the color filter substrate.
Alignment marks 15, 1 independent of
5'is formed at the same time when the reflective film 11 is formed.

FIG. 2 is an enlarged view of the portion A surrounded by the dotted line in FIG. As shown in FIG. 2, the reflective film 11 according to the first embodiment is a mixed oxide thin film 25 (film thickness 35 nm) which is an adhesive layer.
, Silver alloy thin film 26 (thickness 150 nm), mixed oxide thin film 27
(Thickness 70 nm). The mixed oxide thin films 25 and 27 were prepared by adding cerium oxide, tin oxide, and titanium oxide to indium oxide as a base material, and the composition thereof was 32 at% of cerium in terms of metal elements excluding oxygen. (Atomic percent), tin and titanium were 1 to 0.5 at% (atomic percent). In addition, silver alloy, silver, platinum at 0.5at% (atomic percent),
1 at% (atomic percent) of gold and 1 at% (atomic percent) of copper were added.

The reflective film 11 uses a sputtering device,
They are laminated in a vacuum state at a substrate temperature of 100 ° C. or less. After forming the reflective film 11 on the substrate 10, the substrate is subjected to heat treatment (annealing) for heating at a temperature of 300 ° C. for 1 hour. It was done. After that, the color filter 12, the overcoat layer 13, and the transparent electrode 14 are formed into a reflective film by a known method.
The color filter substrate 1 according to the present Example 1 was obtained by sequentially stacking and depositing on 11 layers.

The color filter substrate 1 of the first embodiment is
500 in a high temperature and high humidity environment with a temperature of 60 ° C and a humidity of 95%
After being left for a time, the appearance of the reflective film 11 did not change and defects such as spots did not occur. Further, when the light reflectance of the reflective film 11 was measured before forming the color filter 12, the light reflectance was as good as 90% or more, and there was no problem in practical use.

In the first embodiment, the silver alloy thin film is used.
A mixed oxide thin film 27 was laminated on 26
27 may be omitted. Further, the reflective film 11 of the present invention,
After forming a three-layer structure on the entire surface of the substrate 11, a desired pattern shape can be obtained by performing etching with a sulfuric acid-based etching solution or the like using a known photolithography method. The reflective film 11 having a desired pattern may be formed by using a mask sputtering method using a metal mask having an opening pattern.

Example 2 As shown in FIG. 9, the color filter substrate 1 according to Example 2 is sequentially laminated on a 0.7 mm-thick non-alkali glass substrate 90 (1737 material manufactured by Corning Incorporated). The reflective film 91, the color filter 92 formed by a known pigment dispersion method, the acrylic resin overcoat layer 93, and the transparent electrode 94 having a thickness of 140 nm form a main part. The reflective film 91, the color filter 92, and the overcoat layer according to the second embodiment.
The configuration, material, and forming method of the transparent electrode 94 and the transparent electrode 94 are the same as those of the first embodiment.

Here, in the second embodiment, a round opening 95 having a diameter of 40 μm, which corresponds to about 5% of the effective area of each pixel, is formed in the portion of the reflective film 91 facing the central portion of each pixel of the color filter 92. It is opened so that the light emitted from the back surface of the substrate 90 can pass through the opening 95. In the second embodiment, a reflective film having a three-layer structure is formed on the entire surface of the substrate 90.
After forming 91, the opening 95 is also formed by etching at the same time when the reflection film 91 is formed into a desired pattern shape by etching with a sulfuric acid-based etching solution using a known photolithography method. Further, FIG. 10 is a plan view of the color filter substrate 1 of the second embodiment as viewed from the color filter 92 side, and a round opening 95 provided in the reflective film 91 is shown near the center of each pixel. There is. The shape, size, and position of the opening 95 provided in the reflective film 91 can be adjusted, and may be appropriately set according to the intended use of the color filter substrate 1.

Comparative Example Next, for reference, a comparative example of the color filter substrate of the present invention and the conventional color filter substrate will be described below.

In this comparative example, two types of substrates, that is, an alkali-free glass substrate 51 containing no alkali metal element and an alkali glass substrate 61 containing an alkali metal element were used, and a reflective film was formed on each substrate. It is a thing.

That is, quartz glass is used as the non-alkali glass substrate 51, and soda glass is used as the alkali glass substrate 61 containing an alkali metal element. On each substrate, the reflection film 11 having the same three-layer structure as that described in the above-described Example 1 is laminated and formed, and thereafter, the reflection film is patterned and annealed by the same steps as those in Example 1 above. Two kinds of reflective films with different substrates after processing 11
Is what I got. In this comparative example, silver alloy, silver, gold at 1 at% (atomic percent), and copper at 0.5 at
% (Atomic percent), and the composition of the mixed oxide thin film was the same as in Example 1 above. In addition, in this comparative example, when the thickness of the silver alloy thin film is increased, the reflected light becomes stronger and it becomes difficult to observe.Therefore, the thickness of the silver alloy thin film is as thin as 14 nm, and the mixed oxide with the thickness of 35 nm is used. A thin film sandwiches a silver alloy thin film.

Then, a reflective film having quartz glass as the substrate 51 (a reflective film relating to the color filter substrate of the present invention) was placed in a high temperature and high humidity high pressure tester at a temperature of 120 ° C., a humidity of 100% and a pressure of 2 atm for 10 hours. FIG. 5 is a diagram schematically showing the shape of the reflection film after being left as it is. Similarly, a reflective film with an alkali glass substrate 61 is used at a temperature of 120
FIG. 6 is a drawing schematically showing the shape of a conventional reflective film after being left for 10 hours in a high-temperature and high-humidity high-pressure tester at a temperature of 100 ° C., a humidity of 100% and a pressure of 2 atm. In addition, FIG.
6A and 6B are plan views in which, for example, a reflection film portion patterned in a stripe shape is partially enlarged (1000 times), and a portion between the patterned reflection films 11a and 11b serves as a base. The glass substrate 51 (glass surface 60) and the glass substrate 61 (glass surface 70) are exposed and visible. The cross section taken along line XX 'of FIG. 6 is shown in FIG.
However, the cross section of FIG. 5 is also substantially the same.

As shown in FIG. 5, in the reflection film of the present invention,
No change is seen at the pattern edge 53 of the reflective films 11a and 11b. However, in the reflection film using the substrate 61 made of alkali glass as shown in FIG. 6, the pattern edges 63 of the reflection films 11a and 11b are deteriorated by the alkali metal element melted from the soda glass, and stain-like defects are generated. It was what was there.

The present inventors conducted an analysis by SIMS on the pattern edge 63 portion where the spot-like defect had occurred, and as a result, the mixed oxide surface, the mixed oxide thin film and the silver alloy thin film were obtained. At the interface with, Na (sodium), K
Alkali metal elements such as (potassium) and Ca (calcium) were concentrated and detected.

[0060]

As described above, according to the present invention, it is possible to provide a color filter substrate for a reflective liquid crystal display device having a higher reflectance and a higher reliability than a reflective film using aluminum. . That is, since the edges of the silver alloy thin film that constitutes the reflective film are not exposed to the outside air, deterioration of the reflective film due to the effects of moisture (humidity) and alkali metal elements in the surrounding atmosphere is prevented, and the color filter substrate The resistance is greatly improved.

Further, in the conventional reflection film using aluminum, since aluminum is dissolved by the alkaline solution, in the manufacturing process of the color filter substrate, for example, cleaning using the alkaline solution cannot be performed before forming the color filter. There was a restriction. However, since the reflective film according to the present invention uses the silver alloy thin film and the silver alloy thin film is protected, such restrictions due to alkali have been eliminated. It is possible to move to the post-process of forming the filter without any trouble, and there is a merit that the production efficiency and productivity are improved.

In addition, when the reflective film is aluminum, when an organic material such as a color filter is laminated on the reflective film, the light reflectance of the reflective film is lowered due to the refractive index of the organic material. . However, in the present invention, since a silver alloy thin film is used for the reflective film, even if an organic material such as a color filter is laminated on the reflective film, it is not affected by the organic material and the light reflectance does not decrease. It can be said that the present invention is excellent in practical use.

[0063]

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing an embodiment of a color filter substrate of the present invention.

FIG. 2 is an explanatory cross-sectional view showing a main part of an embodiment of a color filter substrate of the present invention.

FIG. 3 is a cross-sectional explanatory view showing a main part of an example of a reflective liquid crystal display device using a conventional color filter substrate.

FIG. 4 is a cross-sectional explanatory view showing a main part of an example of a conventional color filter substrate.

FIG. 5 is an enlarged view showing a state after a resistance test is performed on the color filter substrate of the present invention.

FIG. 6 is an enlarged view showing a state after performing a resistance test on a conventional color filter substrate.

FIG. 7 is a graph showing an example of X-ray diffraction data.

FIG. 8 is a graph showing another example of X-ray diffraction data.

FIG. 9 is a sectional explanatory view showing another embodiment of the color filter substrate of the present invention.

FIG. 10 is a plan view showing the main part of another embodiment of the color filter substrate of the present invention.

FIG. 11 is an explanatory cross-sectional view showing an example of a reflective film formed on soda glass.

[Explanation of symbols]

1, 2, ......... Color filter substrate 10, 30, 40, 50, 51, 61, 90 11, 31, 41, 91 ・ ・ ・ ・ ・ ・ ・ ・ Reflective film 12, 32, 92 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Color filter 13, 33, 43, 93 ・ ・ ・ ・ ・ ・ ・ ・ Overcoat layer 14, 34, 36, 94 ・ ・ ・ ・ ・ ・ ・ ・ Transparent electrode 15 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Alignment mark 25, 27, 45, 47 ・ ・ ・ ・ ・ ・ ・ ・ Mixed oxide thin film 26, 46 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Silver alloy thin film 35 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ TFT element 37 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Polarizing film 38 ・ ・ ・ ・ ・ ・ ・ ・ ・ Light control film 39 ... 48, 49 ... 53, 63 ................... Pattern edge 60, 70 ................... Glass surface 71, 72, 81, 82 ... X-ray diffraction data 73、83 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Peak 95 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Open hole

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-82762 (JP, A) JP-A-9-179116 (JP, A) JP-A-4-315129 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G02F 1/1335 G02B 5/20 101

Claims (4)

(57) [Claims] 1. An adhesive layer, a silver alloy thin film, and 1
Or a color filter substrate for reflection type liquid crystal display in which color filters having two or more surfaces are sequentially laminated on the substrate, the silver alloy thin film is composed of one electrically independent pattern for each color filter. In addition, when the liquid crystal cell is formed into a liquid crystal display device, the pattern of the silver alloy thin film is not exposed from the end face of the substrate, and the color
Overcoat layer of transparent resin on the filter or
By stacking at least one of the transparent electrodes,
A color filter substrate for a reflective liquid crystal display device, characterized in that the film is entirely covered, and in addition, the surface of the substrate or the substrate itself is made of a material substantially containing no alkali metal element. 2. The reflection type liquid crystal according to claim 1, wherein the silver alloy thin film is a silver alloy thin film capable of transmitting light from the back surface of the substrate by forming an opening in a part of the silver alloy thin film. Color filter substrate for display device. 3. The color filter substrate for a reflective liquid crystal display device according to claim 1, wherein the adhesive layer is an adhesive layer selected from at least one of a metal thin film and a metal oxide thin film. 4. A metal oxide thin film is inserted between the color filter and the silver alloy thin film.
Alternatively, the color filter substrate for the reflective liquid crystal display device according to Item 3.