FR2803843A1 - Glass article used as a substrate for a plasma display screen comprises glass substrate and a barrier film of indium oxide and/or tin oxide to prevent diffusion of metallic ions formed on the substrate surface - Google Patents

Abstract

Barrier film (2) mainly containing indium oxide and/or tin oxide on a glass substrate (1) containing alkali prevents diffusion of metallic ions formed on the substrate surface. Sublayer preventing diffusion of metallic ions formed on the substrate surface may comprise an intermediate layer between the substrate and the barrier film. An insulating film can be formed on the barrier film. The surface electrical resistance of the insulating film is 1.0 \* 10<6> Ohm /square to 1.0 \* 10<6> Ohm /square, preferably even after thermal treatment at 550 deg C for an hour. An electrode film (4) (preferably, comprising silver) is formed on the insulating film. An Independent claim is given for a glass substrate for a screen.

Description

ARTICLE <B><U>EN</U> </B> GLASS <B><U>ET</U> </B> SUBSTRATE <B><U>EN</U> </B> GLASS FOR A FIELD OF THE INVENTION <U> AND </U> PRESENTATION <U> OF THE ART </U> <U> RELATED </U> The present invention relates to a glass article on which a barrier film is formed, the film being capable of exhibiting an excellent effect of preventing simple or mutual diffusion of an alkali into glass and metal when a metal film is formed on a glass surface containing an alkali, and the present invention further relates to a glass substrate for a screen or display panel.

In general, a flat screen or display panel, such as a plasma display panel (PDP), a field effect display (Field Emission Display FED), a liquid crystal display (LCD) ) or an electroluminescent display (ELD), is achieved by forming elements, such as electrodes on two glass substrates and laminating the glass substrates. In particular for the front glass substrates, transparent electrodes, for example made of ITO (indium-tin-oxide) and SnO 2, are employed. Metals, such as Ag, Cr / Cu / Cr, are used as auxiliary electrodes, in particular for a large area screen, in order to decrease the resistance of the electrode wiring. In a glass substrate for a plasma display panel (PDP), a soda-lime glass substrate (containing silica, soda and lime) put in the form of a plate with a thickness of 1, 5 mm to 3.5 mm or an alkali containing glass plate having a lower high annealing temperature (high strain point) is used. These glass substrates are manufactured using a float glass process which is suitable for mass production and achieving excellent surface flatness. During processing, the float glass is exposed to an atmosphere of hydrogen gas, so that a reducing layer with a thickness of several microns is formed on a surface thereof. it is generally known that this reducing layer contains Sn2 + derived from molten Sn.

In the manufacturing process of the plasma display panel, the application of Ag as a bus electrode to a surface of a glass substrate through transparent electrodes is followed by heating to a temperature. at 550 C to 600 C for 20 to 60 minutes and the treatment is repeated several times.

During this heating treatment, Ag + ions are diffused into the transparent electrodes and reach the surface of the glass where the ion exchange between the Ag + ions and the Na 'ions contained in the glass takes place. Therefore, the Ag + ions migrate into the glass and the Ag + ions which have migrated are reduced by the Sn "present in the reducing layer so that Ag colloids are formed. Due to the Ag colloids, the glass substrate is tinted yellow.

This coloring problem due to metallic colloids can occur not only in the case of forming a metal electrode film of Ag, but also in the case of forming another electrode film of a metal such as Cu or Au which diffuses easily. The problem of coloring due to Ag colloids can also arise in a rear window of an automobile having Ag electrodes in the form of strips for demisting.

It has been proposed that in the case of using alkali-containing glass as a substrate for a screen, a barrier film is formed to prevent metal ions from diffusing, thereby preventing ion exchange between the screen. alkali contained in the glass and the Ag or the like used for the electrodes in the case of a plasma display panel and thus avoiding staining of the glass due to colloids of Ag, where the barrier film is made of a metal , a nitride or an oxide such as Si02, Zr02, A1203 and Ti02 (Japanese patent H09-245652A, Japanese patent H10-114549A, Japanese patent H10-302648A, Japanese patent H11-109888A and Japanese patent H11-130471A) .

However, the barrier film cannot provide sufficient efficiency to prevent the diffusion of metal ions. In particular, the nitride barrier film is oxidized during a heating treatment in a manufacturing process of a plasma display, thereby reducing the effectiveness of preventing the diffusion of metal ions.

<U> AIM AND </U> SUMMARY <U> OF </U> THE INVENTION The object of the present invention is to solve the above-mentioned problems and to provide a glass article exhibiting no problem of coloring due to the invention. to metal colloids by virtue of its excellent efficiency in preventing the diffusion of metal ions, and providing a glass substrate for a high quality screen or display comprising the glass article mentioned above.

The glass article of the present invention has a glass substrate containing an alkali and a barrier film formed on a surface of the glass substrate containing an alkali to prevent diffusion of metal ions. The barrier film mainly consists of an indium oxide and / or a tin oxide.

The barrier film mainly consisting of indium oxide (m203) and / or tin oxide (Sn02) has excellent efficiency in preventing the diffusion of metal ions, and thus can effectively prevent elution of the alkali contained. in the glass and prevent the diffusion of metal ions contained in a metal film formed on the surface of the glass plate in the glass.

When the barrier film is formed directly on the alkali-containing glass plate, the alkali compound contained in the glass affects the compactness of the barrier film formed thereon, thereby affecting the effectiveness of preventing the diffusion of metal ions.

That is, when the diffusion barrier film is formed by a physical vapor deposition process, such as a sputtering process, an ion-plating process, or an ion-plating process. evaporation under vacuum, the alkali diffuses as a trace from the glass during film formation and the diffusion of the alkali can affect the crystal structure of the barrier film. In the case of a large amount of diffused alkali, the crystal structure of the barrier film is deteriorated so that the barrier film becomes porous, thereby lowering the effectiveness of preventing the diffusion of metal ions.

When the barrier film for preventing the diffusion of metal ions is formed by an application method, such as a printing method or a sol-gel method, the application operation should be followed by a coating operation. cooking (baking) or heating (firing). The above crystal structure of the barrier film may be deteriorated during the baking or heating operation after the application of the diffusion barrier material. When the barrier film is formed by a chemical vapor deposition (CVD) process, such as a chemical gas deposition process, the same phenomenon as that of the physical vapor deposition process occurs. When the barrier film is formed by the chemical vapor deposition process, the source material used in the process usually contains chlorine, so the material releases chlorine during film formation and the chlorine reacts with the alkali compound contained. in the glass substrate so as to deposit chlorine compounds on the glass substrate. The parts where the chlorinated compounds are formed do not allow the formation of the above barrier film consisting mainly of indium oxide and / or tin oxide, so that the barrier film has pinholes. The diffusion of metal ions cannot be prevented at these parts.

Therefore, in order to eliminate the detrimental effect due to the alkali contained in the glass substrate, an undercoat for preventing the diffusion of alkali ions (hereinafter, sometimes referred to simply as "underlayer") is previously formed on the alkali-containing glass substrate. The barrier film mainly consisting of indium oxide and / or tin oxide is formed on the underlayer, thereby having the effect of securely preventing the diffusion of metal ions. In the glass article of the present invention, an insulating film is formed on the barrier film, if necessary, and an electrode film, preferably containing Ag, is further formed on the insulating film.

The surface electrical resistance of the insulating film is preferably in a range of 1.0 x 106 @ 2 / C to 1.0 x 1016 S210. The surface electrical resistance of the insulating film is preferably maintained in the range of 1.0 x 106 S2 / 0 to 1.0 x 1016 S2 / 0 even after the heating operation at 550 C for one hour, that is, that is, the heating conditions of the usual manufacturing process for display panels or plasma screens.

The glass substrate for a screen of the present invention comprises an alkali-containing glass substrate, an underlayer for preventing the diffusion of alkali ions formed on a surface of the alkali-containing glass substrate, a barrier film consisting mainly of a indium oxide and / or tin oxide to prevent diffusion of metal ions, an insulating film and an electrode film. The surface electrical resistance of the insulating film is within a range of 1.0 x 106 S2 / [] to 1.0 x 1016 52 / E] even after the heating operation at 550 C for one hour. The glass substrate for a screen exhibits no coloration due to metal colloids due to the excellent efficiency in preventing the diffusion of metal ions from the barrier film, so that significantly high quality is obtained.

BRIEF <U> DESCRIPTION OF THE DRAWINGS </U> Fig. 1 is a sectional view showing one embodiment of the glass article of the present invention; Fig. 2 is a sectional view showing another embodiment of the glass article of the present invention; Fig. 3 is a sectional view showing still another embodiment of the glass article of the present invention; and FIG. 4 is a sectional view showing still another embodiment of the glass article of the present invention.

<U> DETAILED DESCRIPTION </U> <U> PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Figs. 1 to 4 are sectional views each showing a glass article according to each embodiment of the present invention, in which a barrier film 2 is formed on a glass substrate 1 and a metal electrode film 4 is formed. on the barrier film 2 directly (Figure 1) or, if necessary, via an insulating film 3 (Figure 2). Alternatively, the barrier film 2 is formed on the glass substrate 1 through an underlayer 5 and the metal electrode film 4 is formed on the barrier film 2 directly (Figure 3) or, if necessary , through the insulating film 3 (Figure 4).

The glass substrate 1 is made of a glass containing an alkali. The main components of alkali-containing glass are as follows.

Si02 50 to 73% by mass A1203 0 to 15% by mass R20 6 to 24% by mass R'0 6 to 27% by mass R20 is the sum of Li20, Na20 and K20, and R 'O is the sum CaO, MgO, SrO and BaO.

Barrier film 2 consists mainly of m203 and / or Sn02.

A film mainly consisting of m203 or SnO2 is generally used as a transparent conductive film. In particular, a film of In203 containing Sn (ITO) in an amount of 5% by mass and a film of SnO2 doped with fluorine or antimony are preferably used because of their low surface electrical resistance. According to the present invention, there is no particular limitation on the concentration of impurities in the barrier film 2 because the diffusion of metal ions can be prevented regardless of the value of the surface electrical resistance. However, when the barrier film 2 is also used as an electrode, the above-mentioned composition exhibiting low surface electrical resistance is preferably used as the barrier film 2. In the case of an application requiring high surface electrical resistance Such as a rear window of an automobile and a substrate for a screen, the insulating film 3 is preferably formed on the barrier film 2 consisting mainly of m203 and / or Sn02 as shown in Fig. 2.

The barrier film 2 has no particular limitation as to the ratio between the content of In203 and the content of SnO2.

The barrier film 2 may mainly contain SnO 2 and may additionally contain Sb 2 O 3, where the preferable ratio between these two components is Sn 2 O: S 2 0 3 = 99.9 - 99.99: 0.01 - 0.1 (wt%) .

As with the barrier film 2 for preventing the diffusion of metal ions, the larger thickness is preferable from the viewpoint of the efficiency of the diffusion barrier of metal ions. However, too great a thickness cannot provide the corresponding effect and, conversely, increases the cost. Therefore, the thickness of the barrier film 2 is preferably in a range of 5 nm to 200 nm, more particularly in a range of 50 nm to 200 nm.

The surface electrical resistance of the insulating film 3 is preferably in a range of 1.0 x 106 çVU to 1.0 x 1016 S2 / 0. More particularly, for a plasma display panel (screen) in which leakage current should be a significant problem, a high surface electrical resistance greater than 1.0 x 1015 S2 / 0, for example in a range of 1, 0x1015 ç2ILI at 1.0 x 1016 SI / E] is preferable. For a field (emission) effect screen (DEF) in which electrification of the substrate is expected to be a significant problem, the surface electrical resistance is preferably in a range of 1.0 x 106 52 / E] to 1.0 x 1012 5211 and, more preferably, in a range between 1.0 x 108 S2 / 0 and 1.0 x 1012 S2 / E.

Since the leakage current and / or electrification of the substrate should be a significant problem when the glass substrate is used as a screen, the above ranges of surface electrical resistance should be maintained even after the heating operation at 550 C for one hour, that is, they should not vary according to the effects of temperature during the operation of manufacturing the screen, for example, during the operation of baking or heating the Ag electrode. An insulating film 3 that is too thick may present cracking problems and increase the cost, while an insulating film 3 that is too thin may not provide stable surface electrical resistance. Therefore, the preferable thickness of the insulating film 3 is within a range of 25nm to 200nm.

There is no particular limit on the material of the insulating film 3. The insulating film 3 can be made of any material which makes it possible to obtain the desired surface electrical resistance and it is preferably made of a film of. high strength such as SiO2, A1203, TiO2, TiON, ZrON or ZnAlO.

According to the present invention, the barrier film 2 or the insulating film 3 can be easily formed on the glass substrate 1 by a physical vapor deposition (PVD) method such as a sputtering method, an ion deposition method or a vacuum evaporation process, a chemical vapor deposition (CVD) process such as a chemical gas deposition process, a printing process, a sol-gel process or the like. There is no particular limitation on the material of the sublayer 5 formed between the barrier film 2 and the glass substrate 1. The sublayer 5 formed between the barrier layer 2 and the glass substrate 1 can be made. made of any material capable of preventing the diffusion of alkali ions (eg Na, K +) and is preferably formed of an oxide or nitride such as SiO2, TiO2, ZnO , A1203, ZrO2, MgO, SiN, TiN or AlN. Among these materials of the sublayer 5, oxides such as SiO 2, ZNO which have excellent machinability are more suitable than the others from the point of view of adhesion at the interface because the barrier film 2 formed on the sublayer 5 consists of an oxide film.

The sublayer 5 can be formed by a chemical vapor deposition (PVD) process such as a sputtering process, an ionic deposition process or a vacuum evaporation process, a chemical vapor deposition process. (CVD) such as a chemical gas deposition process, a printing process, a sol-gel process or the like. The forming method and the forming condition should be selected so that a thin layer formed from the aforementioned material has a compact structure. Among these methods, the sputtering method is suitably employed because it can facilitate the formation of a thin film having a compact structure and it can find a wide range of application in film materials. Using the same process to form the barrier film 2 and the insulating film 3 is industrially advantageous because the glass article of the present invention can be manufactured in a relatively short process. The thickness of the sub-layer 5 can be greater than 10 nm. With a thickness less than 10nm, the formation of a uniform film is impossible and the film formed may be the same as islands. In addition, the desired thickness of the sublayer 5 is greater than 10 nm to completely prevent the diffusion of alkali ions. There is no particular upper limit on the thickness, but a sufficient effect as an underlayer 5 can be obtained with a thickness not exceeding 50 nm. From an industrial point of view, the preferred thickness of the underlayer 5 is in a range of 20nm to 30nm.

In the case of forming the metal electrode film 4 made of Ag or the like on the barrier film 2 or on the insulating film 3, the preferred thickness of the metal electrode film 4 is within a range of 3 µm. at 12 µm.

<U> EXAMPLES </U> The present invention will be described concretely with reference to the following examples and to comparative examples.

<U> Example 1 </U> A soda-lime glass substrate (containing silica, soda, and lime) was prepared using the float glass method. An In203 film was formed as a barrier film to prevent diffusion of metal ions onto the soda lime glass substrate by the sputtering process. The film was formed to have a thickness shown in Table 1 using a target in In, in an argon-oxygen atmosphere and at a pressure of 0.4 Pa (3 x 10-3 Torr) and in direct current (DC) mode. Then, an Ag electrode with a thickness of 8 µm was formed by printing an Ag paste on the InzO3 film and baking it at 550 C for one hour. The degree of coloring was observed visually and the result is shown in Table 1.

<U> Examples 2 to 5, Comparative Examples 1 to 3 </U> Each barrier film shown in Table 1 was formed to have a thickness shown in Table 1 by the spraying process in the same manner as in Example 1, but using a different type of target and a different film-forming atmosphere. Then, an Ag electrode was formed in the same manner as in Example 1. The degree of coloring was observed and the result is shown in Table 1. <U> Example 6 </U> A barrier film of SnO 2 having a thickness shown in Table 1 was formed by heating a soda lime glass substrate to 550 C, blowing a gas composed of a mixture of monobutyl tin trichloride (MBTC), oxygen, nitrogen and vapor and using the chemical vapor deposition (CVD) process. Then, an Ag electrode was formed in the same manner as in Example 1. The degree of coloring was observed and the result is shown in Table 1.

<U> Comparative Example 4 </U> A SiO 2 barrier film having a thickness shown in Table 1 was formed by a chemical vapor deposition process in the same manner as in Example 6, but using monosilane in place of MBTC and using ethylene in place of water vapor. Then, an Ag electrode was formed in the same manner as in Example 1. The degree of coloring was observed and the result is shown in Table 1. <U> Examples 7 to 11 </U> Each sub the layer shown in Table 1 was formed before the formation of a barrier film on a soda-lime glass substrate as formed in Examples 1, 2, 3 and 6.

For Examples 7-10, the sublayer was formed to have a thickness of 20nm by the sputtering process using an oxide target and in the radio frequency mode. For Example 11, the sublayer was formed to have a thickness of 20 nm by the chemical vapor deposition (CVD) process in an identical manner to Comparative Example 4.

For Example 7, a barrier film was formed in the same manner as in Example 1 after forming the SiO 2 sublayer.

For Example 8, a barrier film was formed in the same manner as in Example 1, after forming the TiO 2 sublayer.

For Example 9, a barrier film was formed in the same manner as in Example 2, after forming the SiO 2 underlayer.

For Example 10, a barrier film was formed in the same manner as in Example 3, after forming the SiO2 underlayer. For Example 11, a barrier film was formed in the same manner as in Example 6, after forming the SiO2 underlayer.

On constate à partir du tableau 1 que les exemples selon la présente invention peuvent présenter des effets de prévention significative de la coloration due aux colloïdes d'Ag produits par la diffusion des ions d'Ag. En particulier, on constate également que la sous-couche amplifie l'effet. Then, an Ag electrode was formed for each example, respectively, in the same manner as in Example 1. The degree of coloring was observed for each example and the results are shown in Table 1.

It can be seen from Table 1 that the examples according to the present invention can exhibit effects of significant prevention of the coloration due to the colloids of Ag produced by the diffusion of the ions of Ag. In particular, it is also observed that the sublayer amplifies the effect.

As described in detail, the present invention can provide a glass article having no staining problem due to metal colloids due to its excellent efficiency in preventing the diffusion of metal ions and provide a glass substrate for a high quality screen comprising the glass. glass article mentioned above.

The glass articles of the present invention are extremely useful industrially as a substrate for a screen, an automobile rear window and the like.

Claims (8)

1. A glass article comprising a glass substrate (1) containing an alkali and a barrier film for preventing diffusion of metal ions formed on a surface of said glass substrate containing an alkali, wherein said barrier film (2) consists mainly of an indium oxide and / or a tin oxide. The glass article according to claim 1, wherein said article further comprises an underlayer for preventing the diffusion of alkali ions formed on the surface of said alkali-containing glass substrate (1), and wherein said film barrier (2) is formed on said sublayer (5). 3. A glass article according to claim 1 or 2, further comprising an insulating film (3) formed on said barrier film (2). The glass article according to claim 3, wherein the surface electrical resistance of said insulating film is in a range of 1.0 x 106 S2 / 11 to 1.0 x 1016 S2 / 11. The glass article according to claim 3 or 4, wherein the surface electrical resistance of said insulating film (3) is maintained in the range of 1.0 x 106 S2 / 11 to <B> 1.0 </B> x. 1016 S2 / E] even after heat treatment at 550 C for one hour. A glass article according to any one of claims 3 to 5, further comprising an electrode film (4) formed on said insulating film (3). 7. A glass article according to claim 6, wherein said electrode film (4) comprises Ag. 8. Glass substrate for a screen including. a glass substrate (1) containing an alkali; an underlayer (5) for diffusing alkali ions formed on a surface of said alkali-containing glass substrate (1); a barrier film (2) for preventing the diffusion of metal ions consisting mainly of indium oxide and / or tin oxide; an insulating film (3); and an electrode film (4). said films being formed in the order of their enumeration, and the surface electrical resistance of said insulating film (3) being maintained in a range of j # <B><I>O</I> </B> x 106 S2 / D at 1.0 x 1016 52 / E] even after a heat treatment at 550 C for one hour.