JP2000178777A - UV treatment method for metal oxide surface and UV irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet treatment method which can be performed without deteriorating the original characteristics of a metal oxide by preventing the release of oxygen in the metal oxide, and a method suitable for use in the method. Provided is an ultraviolet irradiation device. SOLUTION: The temperature of the surface of the metal oxide is controlled to be 50 ° C. or higher, and the surface of the metal oxide is irradiated with ultraviolet rays in an atmosphere containing 450 ppm or more of ozone. The apparatus comprises an ultraviolet irradiation chamber 1 to which ultraviolet light is irradiated, and an ozone concentration control means 5 for controlling the ozone concentration in the ultraviolet irradiation chamber 1.
And temperature control means 4 for controlling the temperature of the object to be irradiated with ultraviolet light.
And the ultraviolet ray generating means 2. The ozone concentration control means 5 has an ozone concentration of 450 ppm around the object to be irradiated with ultraviolet light.
The above-described control is performed, and the temperature control means 4 is configured to control the surface temperature of the object to be irradiated with ultraviolet light to be 50 ° C. or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, such as UV / O ₃ cleaning for dirt removal by organic substances ITO membrane surface used in the electrical circuit, suitable disinfection method and to the metal oxide surface And an ultraviolet irradiation device.

[0002]

2. Description of the Related Art Ultraviolet rays have a short wavelength and large energy, and are used in various fields such as chemical synthesis, light cleaning, and fine processing using the energy. On the other hand, metal oxides also have various characteristics depending on their composition, and are therefore used in various areas such as insulating films, transparent conductive films, photocatalysts, and electrode materials. In many cases, the surface of the metal oxide is irradiated with ultraviolet light, and the surface is subjected to some treatment with ultraviolet light.
For example, a transparent electrode made of a metal oxide such as ITO or SnO is used in an LCD panel.
There is a need for improved wettability that leads to improved coating properties of the alignment film. The main factor that hinders the coatability on the metal oxide film is an organic film attached to the surface of the metal oxide.
O ₃ cleaning is employed.

According to this method, ultraviolet rays are irradiated on a metal oxide film in an ozone atmosphere. The ultraviolet rays generate oxygen radicals from ozone and activate organic substances. By the reaction, the organic substance is oxidized and changed into a low molecular oxide such as carbon dioxide or water, so that the organic substance is removed from the surface or is in a state where it is easily removed. In this method, it is necessary to create an ozone atmosphere,
As a method, a method of introducing air or oxygen gas containing oxygen into an ultraviolet irradiation chamber and simultaneously generating ozone from oxygen and irradiating ultraviolet light onto the metal oxide film by irradiating the ultraviolet light, an ozone generator is used. There is a method of introducing the ozone into the ultraviolet irradiation chamber.

[0004]

According to the above-mentioned method of removing the organic film adhering to the surface of the metal oxide film by UV / O ₃ cleaning, the wettability of the surface of the metal oxide film is adjusted to the contact angle of pure water. This can be improved to about 2 °, and this method can be said to be a very excellent method. However, on the other hand,
During the ultraviolet treatment, a phenomenon may occur in which the originally transparent metal oxide film is colored and blackened, and the function as a transparent electrode is impaired. Various investigations have been made. Then, it was found that the cause of the blackening was the breaking of the metal-oxygen bond of the metal oxide caused by the irradiation of the metal oxide with ultraviolet rays and the release of oxygen due to this. Therefore, various methods have been tried, such as shortening the irradiation time of ultraviolet rays, weakening the intensity of ultraviolet rays, and changing the wavelength of ultraviolet rays, but preventing blackening without reducing the effect of improving wettability. It was difficult to do.

[0005] Further, the phenomenon that the metal-oxygen bond of the metal oxide is broken and the oxygen is released by the irradiation of ultraviolet rays is caused by the problem of ITO, S used in the above LCD panel.
This is not a problem peculiar to the UV / O ₃ cleaning of a transparent electrode made of a metal oxide such as nO, and the surface of the metal oxide is eventually irradiated with ultraviolet rays regardless of whether it is aggressive or passive. This is a phenomenon that occurs in the case where it is performed, and is a phenomenon that should be prevented from causing deterioration of the characteristics of the metal oxide.

In view of the above, an object of the present invention is to provide an ultraviolet treatment method which can be performed without deteriorating the original characteristics of a metal oxide by preventing a change in the composition of the metal oxide, in particular, elimination of oxygen. An object is to provide an ultraviolet irradiation device suitable for use.

[0007]

According to the present invention, there is provided a method for treating a metal oxide surface with ultraviolet light, comprising:
The temperature is controlled to be 0 ° C. or higher, and the surface of the metal oxide is irradiated with ultraviolet rays in an atmosphere containing 450 ppm or more of ozone. By controlling the temperature and the ozone concentration in this manner, the speed at which oxygen is released by ultraviolet irradiation and the speed at which oxygen is bonded to the portion from which oxygen has been released are balanced, and as a result, oxygen is prevented from being released by ultraviolet irradiation. It prevents peeling and deterioration of the properties of the metal oxide. The type of metal oxide to which this treatment method can be applied is not particularly limited, but is particularly effective when the metal oxide is a conductive transparent metal oxide. An ultraviolet irradiation apparatus according to the present invention includes an ultraviolet irradiation chamber in which an object to be irradiated with ultraviolet light is placed and irradiated with ultraviolet light, an ozone concentration control means for controlling an ozone concentration in the ultraviolet irradiation chamber, and a temperature of the object to be irradiated with ultraviolet light. Temperature control means for controlling the temperature, and ultraviolet light generating means for generating ultraviolet light to be irradiated, the ozone concentration control means is configured to be controlled so that the ozone concentration around the object to be irradiated with ultraviolet light is 450 ppm or more, The temperature control means is configured to perform control such that the surface temperature of the object to be irradiated with ultraviolet light becomes 50 ° C. or higher.

As the above-mentioned ultraviolet ray generating means, various types can be used. When a low-pressure mercury lamp is used as the ultraviolet ray generating means, the structure of the ultraviolet ray irradiating apparatus is such that the ozone generating apparatus is connected to the ultraviolet ray irradiating chamber. The structure is good. When a low-pressure mercury lamp is used as the ultraviolet ray generating means, a structure in which a plurality of mercury lamps are attached in close contact with a lamp block on the outer surface of one cooling pipe through which a cooling medium passes is preferable.

Further, as the ultraviolet ray generating means, 20
A dielectric barrier discharge lamp that emits ultraviolet light having a wavelength of 0 nm or less is particularly suitable. In this case, it is not necessary to attach an ozone generator.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be further described with reference to embodiments. FIG. 1 is a schematic diagram of an apparatus structure showing an example of an ultraviolet irradiation apparatus according to the present invention. This apparatus comprises an ultraviolet irradiation chamber 1 in which an ultraviolet irradiation object is placed and irradiated with ultraviolet light, an ozone concentration control means 5 for controlling the ozone concentration in the ultraviolet irradiation chamber 1, and a temperature of the ultraviolet irradiation object. Temperature control means 4 for controlling the temperature and ultraviolet light generating means 2 for generating ultraviolet light to be irradiated.
The above-described control is performed, and the temperature control unit is configured to control the surface temperature of the object to be irradiated with ultraviolet light to be 50 ° C. or higher.
Further, an ozone generator 6 is connected to the apparatus, and ozone is supplied from an ozone spray nozzle 10 and an exhaust port 8 is provided, so that the atmosphere containing high concentration of ozone can be safely discharged. It is configured as follows.

The ozone concentration control means 5 is connected to the ozone concentration measurement sensor 7 and the ozone generator 6, receives a concentration information signal from the ozone concentration measurement center 7, and receives the ozone concentration signal from the ozone generator based on the signal. The amount of generation was adjusted, and the ozone concentration around the sample table 3 on which the object to be irradiated with ultraviolet light was placed was 4
This is an electric circuit that is controlled to be 50 ppm or more. The upper limit of the ozone concentration is 500
It is preferable that the concentration is controlled so as to be not more than 00 ppm. The higher concentration has no meaning in the processing efficiency, and on the contrary, it tends to adversely affect other parts such as the ultraviolet irradiation object and the apparatus main body. That's why.

The temperature control means 4 is based on a resistance heater 9 embedded in the sample stage 3, a temperature sensor (not shown) for measuring the temperature of the sample stage, and a temperature information signal input from the temperature sensor. The power supply to the resistance heater 9 is adjusted so that the surface temperature of the object to be irradiated with ultraviolet light becomes 50 ° C. or more based on the relationship between the temperature of the sample table 3 and the temperature of the surface of the object to be irradiated with ultraviolet light determined in advance. Is an electric circuit to be controlled.
The upper limit of the control temperature varies depending on the object to be irradiated with ultraviolet rays. However, when a transparent conductive metal oxide film is formed on a glass substrate serving as an LCD panel and this metal oxide surface is subjected to ultraviolet treatment, The upper limit of the temperature is preferably set to 200 ° C., and the temperature is controlled so as not to rise.

The ultraviolet ray generating means 2 is a lamp unit to which a plurality of low-pressure mercury lamps are attached. FIG.
FIG. 2 is a schematic structural diagram illustrating an example of a structure of a lamp unit. A lamp unit having this structure includes a lamp block 22 of a low-pressure mercury lamp 21 on one surface of a square tube 23 made of stainless steel or the like.
Are mounted in close contact with each other, and cooling water is caused to flow through the square tube 23 to cool the plurality of mounted lamps 21 by a common cooling tube. The lamp unit having this structure has lower cost and better cooling efficiency than those in which a plurality of water cooling plates are attached to a lamp block for each lamp. The end of the square tube is closed by welding or the like with a metal plate to which a nipple is attached.

When a low-pressure mercury lamp is used as an ultraviolet ray generating means, the concentration of ozone is set to 100 to 300 ppm unless ozone is introduced from the outside. Difficult to create ozone concentration. Therefore, when a low-pressure mercury lamp is used, it is preferable to provide an ozone generator in this way.

Further, as an ultraviolet ray generating means, 200 nm
When a dielectric barrier discharge lamp emitting the following ultraviolet light is used, the efficiency of ozone generation from oxygen is increased, and the ozone concentration can be easily controlled to 450 ppm or more without installing an ozone generator. In particular, a dielectric barrier discharge lamp in which xenon gas or a gas mainly composed of xenon is filled has a short wavelength of 172 nm, and is particularly efficient and efficient.

Although the apparatus of the present invention is widely used for ultraviolet irradiation, it is suitable for performing light ashing such as removal of a resist or ultraviolet irradiation for light cleaning. Particularly suitable for light cleaning. The ultraviolet treatment method of the present invention is carried out, for example, by using the above-described ultraviolet irradiation apparatus of the present invention, but using, as an example, a case where the present invention is applied to the surface of a transparent conductive metal oxide film used for an LCD panel. Hereinafter, the ultraviolet treatment method of the present invention will be described in more detail.

For the LCD panel, a transparent electrode made of a metal oxide such as ITO or SnO is used.
In order to improve the coating property of the alignment film on the transparent metal oxide thin film, it is required to improve the wettability of the surface of the transparent metal thin film. The ultraviolet treatment method of the present invention can be used for improving this wettability.

For example, a substrate in which an ITO thin film is formed on a glass substrate is mounted on the sample stage 3 of the apparatus shown in FIG. Can improve the overall wettability,
Moreover, blackening of the ITO thin film does not occur. In the ultraviolet treatment method of the present invention,

The substrate is heated and the temperature of the surface of the ITO thin film is set to 5
The temperature is controlled so as to be 0 ° C. or more, and the ozone concentration around the surface of the ITO thin film is made 450 ppm or more. The reason for increasing the surface temperature and increasing the ozone concentration in this way is to prevent the ITO thin film from being blackened, whereby the amount of ultraviolet light reaching the surface is reduced and a large amount of ozone is generated. This is presumably because oxygen atoms diffuse into the transparent metal oxide due to heat and compensate for the released oxygen, thereby preventing blackening. Under such conditions, the time required for improving the wettability is also reduced. In addition, the wettability is improved up to a contact angle of pure water of about 2 °.

The temperature of the surface of the ITO thin film is preferably as low as possible in consideration of the influence on other parts of the substrate.
If the temperature is lower than the above, a phenomenon of blackening will be observed. Therefore, it is preferable to set the temperature higher than this. The ozone concentration is preferably as low as possible in consideration of the influence on other parts of the substrate and the apparatus main body, but is preferably 450 ppm or more to prevent the occurrence of blackening, preferably 500 ppm.
It is good to be more than ppm. And the upper limit is 50
It is better to be 000 ppm. This condition is the same even in the case of a SnO thin film, for example.

It is preferable to use ultraviolet rays having a wavelength of 260 nm or less, and particularly to include ultraviolet rays having a wavelength of 254 nm. This is because the efficiency of generating oxygen radicals from ozone is increased. Furthermore, 2
It is preferable to include those having a wavelength of 00 nm or less, because the efficiency of generating ozone from oxygen increases. In addition, such ultraviolet light having a short wavelength has a large absorption coefficient due to the metal oxide, and is absorbed on the very surface of the oxide, and does not cause the desorption of oxygen due to the ultraviolet light inside the metal oxide. .

When a low-pressure mercury lamp is used as a light source, 254
It is preferable in this respect because it emits two types of ultraviolet rays, i.e., nm and 185 nm. However, it is difficult to increase the ozone concentration by itself, so it is preferable to generate ozone by an external ozone generator and introduce it into the irradiation chamber.

On the other hand, in the case of using a dielectric barrier discharge lamp which emits ultraviolet rays of 200 nm or less, it is preferable in this respect that an ozone concentration of 450 ppm or more can be easily secured by treating in an air or oxygen atmosphere. In particular, those containing xenon gas emit ultraviolet rays of 172 nm. Particularly, ultraviolet rays of this wavelength have a high efficiency of generating ozone from oxygen, and therefore those containing xenon gas are good.

[0024]

EXAMPLES The effects of the ultraviolet treatment performed to improve the wettability of the ITO film surface, which is a transparent conductive metal oxide thin film deposited on a glass substrate, will be described below. The evaluation of the effect by the treatment of the ultraviolet ray is performed by dropping pure water on the ITO film surface,
The contact angle of the resulting polka dot with respect to the surface was measured by using a contact angle meter. Note that the same device as that shown in FIG. 1 was used for ultraviolet irradiation.

(Example 1) Under the condition that the substrate temperature is 50 ° C and the atmosphere in the ultraviolet irradiation chamber is in an atmospheric state with an ozone concentration of 500 ppm, a low-pressure steam mercury lamp is used as an ultraviolet light source.
Ultraviolet rays were irradiated on the surface of the ITO film. The UV intensity of the light source was 254 with no ozone on the ITO film surface.
nm ultraviolet light is 50 mW / cm ² , 185 nm ultraviolet light is 1
3 mW / cm ² . As a result of this irradiation, irradiation time 60
Within seconds, the contact angle of pure water was 2 °, and no blackening of the ITO film occurred.

Example 2 Under a condition that the substrate temperature is 100 ° C. and the atmosphere in the ultraviolet irradiation chamber is an atmospheric state with an ozone concentration of 500 ppm, ultraviolet light was irradiated on the ITO film surface using a low-pressure vapor mercury lamp as an ultraviolet light source. The UV intensity of the light source was 254 with no ozone on the ITO film surface.
nm ultraviolet light is 50 mW / cm ² , 185 nm ultraviolet light is 1
3 mW / cm ² . As a result of this irradiation, the irradiation time 45
Within seconds, the contact angle of pure water was 2 °, and no blackening of the ITO film occurred.

Example 3 Under the condition that the substrate temperature was 100 ° C. and the atmosphere in the ultraviolet irradiation chamber was an atmospheric state with an ozone concentration of 10,000 ppm, ultraviolet light was irradiated onto the ITO film surface using a low-pressure vapor mercury lamp as an ultraviolet light source. The UV intensity of the light source is 2 in the absence of ozone on the ITO film surface.
It was 13 mW / cm ² at 50mW / cm ^2, 185nm UV at 54nm UV. As a result of this irradiation, the contact angle of pure water became 2 ° in an irradiation time of 30 seconds, and no blackening of the ITO film occurred.

Example 4 Under the condition that the substrate temperature was 50 ° C. and the atmosphere in the ultraviolet irradiation chamber was an atmospheric state with an ozone concentration of 600 ppm, ultraviolet light was irradiated on the surface of the ITO film using a xenon gas-filled dielectric barrier discharge lamp as an ultraviolet light source. . The ultraviolet light intensity of the light source was 5 mW / cm ² with 172 nm ultraviolet light without ozone on the ITO film surface. In this case, the ozone concentration was adjusted by adjusting the displacement without using the ozone generator. As a result of this irradiation, the contact angle of pure water was 2 ° with an irradiation time of 30 seconds, and I
No blackening of the TO film occurred.

(Comparative Example) A low-pressure steam mercury lamp was used as an ultraviolet light source under the condition that the substrate temperature was 30.degree.
Ultraviolet rays were irradiated on the O film surface. The UV intensity of the light source is
254n on the surface of the ITO film without ozone
50 mW / cm ² at 185 nm UV, 13 at 185 nm UV
mW / cm ² . As a result of this irradiation, the contact angle of pure water became 2 ° at an irradiation time of 90 seconds, but the ITO film turned black when the irradiation time passed 45 seconds. The results are shown in FIG. FIG. 3 is a graph showing the change in the treatment time and the contact angle of pure water on the surface of the ITO film in the above Examples and Comparative Examples. As can be seen from this graph, 172n
UV treatment using UV light of m is most effective for improving the wettability of the ITO film surface. When the substrate temperature was set to 50 ° C. and the ozone concentration was set to 150 ppm in the same manner as in Example 1, the contact angle of pure water was 2 °, but blackening could not be prevented. , Ozone concentration 450
Under the condition of ppm, the contact angle of pure water of 2 ° was achieved, and blackening was prevented.

[0030]

According to the ultraviolet treatment method of the present invention, a change in the composition of the metal oxide, particularly the elimination of oxygen, can be prevented, and the ultraviolet treatment can be performed without lowering the original characteristics of the metal oxide. . Further, according to the ultraviolet irradiation apparatus of the present invention, the ultraviolet treatment can be performed by using the ultraviolet treatment method of the present invention without lowering the original characteristics of the metal oxide. Further, according to the ultraviolet treatment method of the present invention, blackening of the transparent conductive metal oxide can be prevented, and the wettability of the surface of the transparent conductive metal oxide can be improved in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of an example of an ultraviolet irradiation apparatus according to the present invention.

FIG. 2 is a schematic structural diagram illustrating an example of a structure of a lamp unit.

FIG. 3 shows processing time and ITO in Examples and Comparative Examples.
4 is a graph showing a change in a contact angle of pure water on a film surface.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultraviolet irradiation room 2 Ultraviolet ray generating means 3 Sample stand 4 Temperature control means 5 Ozone concentration control means 6 Ozone generator 7 Ozone concentration measuring sensor 8 Exhaust port 9 Resistance heating heater 10 Ozone spray nozzle 21 Low pressure mercury lamp 22 Lamp block 23 Square tube

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G042 DA01 DB15 DB21 DB22 DB24 DB35 DC01 DE03 DE12 4G075 AA30 AA61 AA63 CA03 CA15 CA33 EB31 4K053 PA01 QA01 RA02 SA01 SA20 XA11 XA50

Claims (6)

[Claims] 1. A metal, wherein the temperature of a predetermined metal oxide surface is controlled to be 50 ° C. or higher, and the metal oxide surface is irradiated with ultraviolet rays in an atmosphere containing 450 ppm or more of ozone. UV treatment method for oxide surface. 2. The method according to claim 1, wherein the metal oxide is a conductive transparent metal oxide. 3. An ultraviolet irradiation chamber in which an object to be irradiated with ultraviolet light is placed and irradiated with ultraviolet light, an ozone concentration control means for controlling the concentration of ozone in the ultraviolet irradiation chamber, and a temperature of the object to be irradiated with ultraviolet light. Temperature control means, and ultraviolet light generation means for generating ultraviolet light to be irradiated, wherein the ozone concentration control means is controlled so that the ozone concentration around the object to be irradiated with ultraviolet light becomes 450 ppm or more, Is an ultraviolet irradiation apparatus characterized in that the surface temperature of the object to be irradiated with ultraviolet rays is controlled to be 50 ° C. or higher. 4. The ultraviolet ray generating means is a low-pressure mercury lamp, and the low-pressure mercury lamp has a structure in which a plurality of mercury lamps are mounted on an outer surface of a cooling pipe through which a cooling medium is passed, with a lamp block closely attached thereto. The ultraviolet irradiation device according to claim 3, wherein 5. The ultraviolet irradiation apparatus according to claim 3, wherein said ultraviolet generation means is a low-pressure mercury lamp, and an ozone generator is connected to said ultraviolet irradiation chamber. 6. An ultraviolet irradiation apparatus according to claim 3, wherein said ultraviolet ray generating means is a dielectric barrier discharge lamp which emits ultraviolet rays having a wavelength of 200 nm or less.