JP2004152842A - Processing method by ultraviolet light irradiation and ultraviolet light irradiation device - Google Patents

Abstract

An object of the present invention is to provide an ultraviolet light irradiation method for irradiating an object to be processed with ultraviolet light in an atmosphere of a processing gas containing oxygen to perform surface treatment by relatively inexpensive cost and simple equipment. It is an object of the present invention to provide a processing method capable of improving efficiency and reducing processing time.
An irradiation method using ultraviolet light irradiation according to the present invention includes a lamp that emits vacuum ultraviolet light in a lamp house, and a window for applying vacuum ultraviolet light is arranged in the lamp house. In a light irradiation method using an ultraviolet light irradiation device for irradiating a separated object with light through the window, air is supplied to a space between the window and the object.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for performing surface treatment by irradiating an object to be treated with ultraviolet light in a treatment gas atmosphere containing oxygen. More specifically, a cleaning method and apparatus for irradiating an organic substance attached to the surface of an object such as a substrate for manufacturing a liquid crystal display (LCD) or a semiconductor silicon wafer with ultraviolet light, and a method of irradiating the surface of the object with ultraviolet light The present invention relates to a light irradiation method and a device for improving lightness.
[0002]
[Prior art]
In general, ultraviolet light having a wavelength shorter than 200 nm is particularly called vacuum ultraviolet light and is distinguished from ultraviolet light having a wavelength longer than 200 nm. This is because ultraviolet light having a wavelength of 200 nm or less is hardly allowed to proceed in the atmosphere because it is absorbed by oxygen atoms and molecules containing oxygen atoms. On the other hand, this vacuum ultraviolet light has high energy and can cut off the connectors of organic substances, so that it is industrially useful for light cleaning and surface modification, and various vacuum ultraviolet light irradiation devices are used.
[0003]
In particular, in ultraviolet light (UV) ozone cleaning, conventionally, ultraviolet light having a wavelength of 254 nm is irradiated in a reaction tank using ozone generated by an ozone generator, or light having wavelengths of 185 nm and 254 nm generated from a low-pressure mercury lamp is used. Ozone was generated using light having a wavelength of 185 nm, and cleaning was performed using light having a wavelength of 254 nm.
The mechanism of UV ozone cleaning will be briefly described. Ultraviolet light having a wavelength of 242 nm or less can dissociate oxygen molecules O ₂ into oxygen atoms O, and the dissociated oxygen atoms O combine with oxygen molecules to generate ozone (O ₃ ), one of active oxygen species. Generate. Although this ozone has a high oxidizing ability, it absorbs the ultraviolet light and dissociates into excited oxygen atoms O ( ¹ D) and oxygen molecules O ₂ , so that the active oxygen species having a higher oxidizing ability than the ozone, Oxygen atoms O ( ¹ D) can be generated. In light dry cleaning, the organic substance on the surface of the object to be treated is vaporized by the cooperative action of the oxidizing action of the active oxygen generated by these reactions and the effect of cutting the molecular bond of the organic substance on the surface of the article by ultraviolet light. Cleaning or surface treatment is performed by volatilizing low molecular weight compounds such as H ₂ O and carbon dioxide gas CO ₂ .
[0004]
In recent years, excimer lamps have been developed as light sources for use in light cleaning and the like. For example, a xenon excimer lamp in which xenon gas is sealed can efficiently emit light having a wavelength of 172 nm. It is possible to produce a high concentration and to wash the object to be processed at a high speed.
[0005]
However, as described above, light having a wavelength of 200 nm or less usually hardly travels in the atmosphere, so that in a conventional UV cleaning device or the like, the distance between the excimer lamp and the irradiation target is extremely reduced, or the distance between the excimer lamp and the irradiation target is very small. When a distance is required, an inert gas atmosphere is provided in the space up to the irradiation object.
[0006]
A cleaning apparatus using such an excimer lamp is disclosed in Japanese Patent Application Laid-Open No. 2001-113163 for the purpose of improving the processing speed. A device provided with a gas inflow means is disclosed. Specifically, it is disclosed that the cleaning rate can be improved by flowing nitrogen gas alone or flowing a wet nitrogen gas passed through pure water, that is, nitrogen gas + water vapor.
[0007]
FIG. 4 is a schematic view of a conventional irradiation apparatus. The ultraviolet light irradiation device 41 includes an excimer lamp 42 that emits vacuum ultraviolet light inside a lamp house 43, and irradiates vacuum ultraviolet light from an irradiation window 44 toward an irradiation object 45. A space is provided between the irradiation object 45 and the irradiation window 44, and nitrogen is jetted from a nitrogen jet port 46, which is an inert gas inflow means provided in the lamp house 43, to change the atmosphere in the space S1. The atmosphere is nitrogen.
[0008]
However, in the irradiation device 41 in which the nitrogen gas is introduced by providing the inert gas inflow means, not only the cost is greatly increased depending on the flow rate of the nitrogen gas, but also the control of the flow rate and the control of the mixing ratio with water vapor are controlled. Therefore, there is a problem that the apparatus itself becomes large-scale as a result.
[0009]
Further, if the space S1 from the excimer lamp 42 to the irradiation object 45 is completely made into a nitrogen atmosphere, the vacuum ultraviolet light radiated from the excimer lamp 42 reaches the irradiation object 45 sufficiently but generates ozone. There was a problem that processing such as washing could not be performed.
[0010]
On the other hand, when the space S1 between the excimer lamp 42 and the irradiation target 45 in the irradiation device 41 is filled with air, the vacuum ultraviolet light emitted from the excimer lamp 42 sufficiently emits the irradiation target 45. There was a problem that did not reach.
[0011]
[Patent Document 1]
JP 2001-113163 A
[Problems to be solved by the invention]
The present invention provides an ultraviolet light irradiation method for performing surface treatment by irradiating an object to be processed with ultraviolet light in an atmosphere of a processing gas containing oxygen, in which the processing efficiency is reduced by relatively inexpensive cost and simple facility means. It is an object of the present invention to provide a processing method that can improve the processing time.
[0013]
[Means for Solving the Problems]
The irradiation method using ultraviolet light irradiation of the present invention includes a lamp for emitting vacuum ultraviolet light in a lamp house, a window for irradiating vacuum ultraviolet light is disposed in the lamp house, and the irradiation target is separated from the window. A light irradiation method using an ultraviolet light irradiation device for irradiating an object with light through the window, characterized in that air is caused to flow in a space between the window and the object to be irradiated.
[0014]
Thereby, a flow occurs in the air existing in the space between the window surface and the irradiation object, and the active oxygen concentration in the space is made uniform near the window surface and the irradiation object. . That is, there is an advantage that the active oxygen amount in the vicinity of the irradiation object is substantially increased, and as a result, the cleaning speed can be increased.
[0015]
Further, the ultraviolet irradiation apparatus of the present invention includes a lamp for radiating vacuum ultraviolet light in a lamp house, a window for irradiating vacuum ultraviolet light is arranged in the lamp house, and an irradiation target separated from the window. In the ultraviolet light irradiation apparatus for irradiating light through the window, a nozzle for flowing air into a space sandwiched between the window and the object to be irradiated is provided.
[0016]
This allows air to flow into the space between the window and the irradiation object. In addition, with the flow of air, high-concentration ozone near the window surface generated by vacuum ultraviolet light is diffused and averaged in the space, so that the ozone concentration on the surface of the processing object is substantially reduced to air. This is higher than before flowing and has the effect of improving the cleaning speed.
[0017]
Further, the distance between the window and the space sandwiched between the objects to be irradiated is not more than 5 mm.
[0018]
Accordingly, there is an advantage that even in the air, the vacuum ultraviolet light reaches the object to be irradiated, and sufficient active oxygen can be generated, so that a sufficient cleaning effect can be obtained.
[0019]
Further, a nozzle for flowing air into a space sandwiched between the window and the side surface of the irradiation object is provided separately from the irradiation device.
[0020]
Thereby, there is an advantage that the irradiation apparatus itself can be downsized.
[0021]
Further, in addition to the above-described invention, the nozzle controls an air outflow direction so that air can be blown to the vicinity of the window surface.
[0022]
Thereby, after the vacuum ultraviolet light emitted from the window surface reacts with oxygen in the vicinity of the window surface to generate active oxygen, the active oxygen is efficiently transported to the irradiated object side, and newly generated. There is an advantage that oxygen to react can be supplied.
[0023]
Further, in addition to the above-mentioned invention, a transport device for roller-transporting the object to be irradiated is arranged on the window surface side in the above.
[0024]
Accordingly, there is an advantage that even when the size of the object to be irradiated is larger than the vacuum ultraviolet light irradiation area of the irradiation apparatus such as a large liquid crystal substrate, the cleaning process can be performed smoothly.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic view of an ultraviolet light irradiation apparatus used for the treatment by ultraviolet irradiation of the present invention. An ultraviolet light irradiation device 10 of the present invention includes a xenon excimer lamp 2 that generates vacuum ultraviolet light having a wavelength of 172 nm in a lamp house 1, and a cooling block 3 that contacts a part of the excimer lamp 2 is provided. An irradiation window 5 is provided which includes a nitrogen inlet 11a and a nitrogen outlet 11b for purging the interior of the lamp house 1 with an inert gas, and for extracting vacuum ultraviolet light emitted from the excimer lamp 2. In the lamp house 1, a reflection mirror 4 for efficiently irradiating vacuum ultraviolet light emitted from the excimer lamp 2 to the outside is arranged.
[0026]
In addition, the vacuum ultraviolet light emitted from the lamp house 1 is emitted toward an irradiation target 6 arranged in parallel at a position away from the irradiation window 5 by an irradiation distance d. Further, the irradiated object 6 is moved and processed at a constant transport speed by a transport device, for example. Further, a nozzle 7 for flowing air into a space S between the irradiation window 5 and the irradiation target 6 of the ultraviolet light irradiation device 10 is arranged. A certain amount of air 8 jetted from the nozzle 7 is blown in the surface direction of the irradiation window 5.
[0027]
The UV ozone cleaning rate in the same apparatus was measured using a non-alkali glass plate which is a substrate used in a liquid crystal substrate manufacturing process. FIG. 2 shows the measurement results. The vertical axis in FIG. 2 is the contact angle of pure water, and the horizontal axis is the time converted from the transport speed when the substrate to be irradiated is roller-transferred to the irradiation time of the ultraviolet light applied to the substrate. Each of the measurement data is obtained when the air was measured in the atmosphere without flowing air, when air was flowed at 1 L / min, 5 L / min, 7 L / min, and when nitrogen was flowed at 7 L / min as a comparative measurement.
[0028]
In the UV ozone cleaning, the organic component adhering to the substrate is decomposed and cleaned by ultraviolet rays, whereby the wettability of the substrate surface is improved and the contact angle is reduced. In FIG. 2, the contact angle is high when the irradiation time of ultraviolet light is short, and the contact angle is low when the irradiation time is long. In addition, the effect in each processing atmosphere is that, for example, when the irradiation time is about 8 seconds, the contact angle between the case where the air flow rate is 5 L / min and 7 L / min and the case where the nitrogen flow rate is 7 L / min by the irradiation in the atmosphere are as follows. Have the same degree of effect. In addition, for example, when the irradiation time is about 6 seconds, the cleaning speed is higher when the air is supplied than when the air is not supplied. Furthermore, the contact angle at each irradiation time has a cleaning curve substantially equal between the case where air flows at 7 L / min and the case where nitrogen flows at 7 / min.
[0029]
FIG. 3 shows a concentration distribution of ozone generated when vacuum ultraviolet rays having a wavelength of 172 nm are irradiated into the atmosphere from the ultraviolet irradiation apparatus 10 described above. The vertical axis indicates the concentration of ozone, and the horizontal axis indicates the distance from the irradiation window of the vacuum ultraviolet light irradiation device. For the measurement of the ozone concentration, the absorbance of light having a wavelength of 254 nm was measured at each point away from the irradiation window 5. However, the measurement was performed without flowing air from the nozzle.
[0030]
As is clear from the measurement results, high concentration of ozone is present in the vicinity of the surface of the irradiation window 5 and almost no ozone is generated at a point 10 mm or more from the surface of the irradiation window 5. . The measurement shows that ozone is efficiently generated within a distance of 5 mm from the surface of the irradiation window 5 and is a useful region for cleaning or the like.
[0031]
【The invention's effect】
According to the cleaning method of the present invention, the amount of active oxygen in the vicinity of the irradiation object can be increased, and as a result, the cleaning speed can be increased.
[0032]
Further, since the ultraviolet light irradiation device of the present invention can flow air into the space between the window and the object to be irradiated, high concentration ozone generated near the window surface generated by vacuum ultraviolet light is diffused. By averaging in the space, the ozone concentration on the surface of the object to be treated is substantially increased, which has the effect of improving the cleaning speed.
[0033]
In addition, since the distance from the window surface to the object to be irradiated is 5 mm or less, even in the air, the vacuum ultraviolet light reaches the object to be irradiated, and sufficient active oxygen can be generated. There is an advantage that an effect can be obtained.
[0034]
Further, by directing the nozzle toward the window surface, the vacuum ultraviolet light reacts with oxygen near the window surface to generate active oxygen, and then the active oxygen is efficiently transported to the irradiated object side. In addition, there is an advantage that newly reacting oxygen can be supplied.
[0035]
Furthermore, there is an advantage that even if the object to be irradiated becomes large, the object to be irradiated can be transported to the irradiation apparatus, and a sufficient cleaning effect can be obtained without replacing the irradiation part with an inert gas or the like. .
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing an ultraviolet light irradiation apparatus according to the present invention; FIG. 2 is a view showing a relationship between a vacuum ultraviolet light irradiation time on a workpiece and a contact angle of pure water according to the present invention; FIG. 4 is a diagram showing an ozone concentration distribution according to a distance from a window surface in the present invention. FIG. 4 is a schematic diagram of a conventional ultraviolet light irradiation apparatus.
DESCRIPTION OF SYMBOLS 1 Lamp house 2 Xenon excimer lamp 3 Cooling block 4 Reflection mirror 5 Irradiation window 6 Irradiated object 7 Nozzle 8 Spouted air 10 Ultraviolet light irradiator 11a Nitrogen inlet 10b Nitrogen outlet S Space between irradiation window and workpiece d Irradiation distance 41 Ultraviolet light irradiator 42 Excimer lamp 43 Lamp house 44 Irradiation window 45 Irradiated object 46 Nitrogen outlet S1 Space between irradiation window and treated object

Claims (6)

A lamp for radiating vacuum ultraviolet light is provided in the lamp house, and a window for irradiating vacuum ultraviolet light is arranged in the lamp house. A method for processing by ultraviolet light irradiation, wherein air is flowed in a space between the window and the object to be irradiated, using a light irradiation apparatus. A lamp for radiating vacuum ultraviolet light is provided in the lamp house, and a window for irradiating vacuum ultraviolet light is arranged in the lamp house, and an ultraviolet light for irradiating an object to be irradiated separated from the window through the window is provided. In the light irradiation device,
An ultraviolet light irradiation device comprising a nozzle for flowing air in a space between the window and the object to be irradiated. 3. The ultraviolet light irradiation device according to claim 2, wherein a distance between the window and the space sandwiched between the objects to be irradiated is 5 mm or less. 4. 3. The ultraviolet light irradiation device according to claim 2, wherein a nozzle for flowing air into a space sandwiched between the window and a side surface of the irradiation object is provided separately from the irradiation device. 4. 5. The ultraviolet light irradiation device according to claim 2, wherein the nozzle controls an air outflow direction so that air can be blown to the vicinity of the window surface. 6. 6. The ultraviolet light irradiation apparatus according to claim 2, wherein a conveying device for roller-conveying the object to be irradiated is disposed on the window side.

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