JP4281701B2 - Excimer light irradiation equipment - Google Patents

Description

  The present invention relates to an excimer light irradiation apparatus that irradiates excimer light having an emission peak in a vacuum ultraviolet region by excimer discharge, and more particularly to an excimer light irradiation apparatus that can perform high-power irradiation uniformly over a large area.

  Conventionally, ultraviolet irradiation has been performed on an object to be irradiated in a sterilization apparatus, a cleaning apparatus, a resin curing apparatus, a film forming apparatus using a chemical vapor deposition method (CVD method), or the like. An excimer light irradiation apparatus is used for such ultraviolet irradiation treatment. By using such an apparatus, the processing speed can be increased and the cost of processing can be reduced. In order to improve the processing speed, it is necessary to increase the area and output of the excimer light irradiation apparatus. In addition, in an excimer light irradiation apparatus used for a film forming apparatus or the like, the uniformity of excimer light illuminance distribution is particularly strictly required in order to form a film with a uniform film thickness.

  A conventional excimer light irradiation apparatus employs a structure in which an excimer lamp that emits excimer light by excimer discharge is disposed in a casing. However, in such an apparatus, the excimer lamp is composed of a discharge vessel having a double tube structure in which an arc tube is arranged coaxially, and therefore the material constituting the discharge vessel is quartz glass. As a result, the discharge vessel is damaged, and the cost of such an apparatus is high, so that it is difficult to configure the apparatus so as to cope with an increase in the area of the object to be processed.

  In order to solve such a problem, Japanese Patent No. 3125191 discloses an excimer light irradiation apparatus that can cope with an increase in area and output of an object to be processed and that can obtain uniform planar light emission. Has been proposed.

FIG. 7 is a front sectional view of the excimer light irradiation device disclosed in the above publication.
This excimer light irradiation device is provided inside the casing 1 on the circumferential side of the cylindrical metal electrode (outer electrode 2), the rod-shaped metal electrode (inner electrode 3) installed on the central axis thereof, and the inner electrode 3. A plurality of electrode units 5 made of the dielectric 4 formed are arranged. The housing 1 is filled with a discharge gas, and a high-frequency voltage is applied between the outer electrode 2 and the inner electrode 3 by a high-frequency power source 8 to generate a discharge between the electrodes 2 and 3. Excimer light is irradiated through a light exit window 6 attached to the vertical casing 1.

  According to such an excimer light irradiation apparatus, the area can be increased by arranging a large number of electrode units 5. Moreover, since the discharge volume can be increased by increasing the total length of the electrodes 2 and 3 in the electrode unit 5, high output can be achieved. In particular, by allowing gas to flow into the housing 1 and flowing gas between the electrodes 2 and 3 of each electrode unit 5, it is possible to suppress an increase in gas temperature, and thus further increase in output can be expected. Furthermore, uniform planar light emission can be obtained by closely arranging the electrode units 5 adjacent to each other.

Japanese Patent No. 3125191

  In the excimer light irradiation apparatus shown in the above publication, when a plurality of electrode units 5 generate a discharge, the same number of high frequency power supplies are not connected to the electrode units 5, but one high frequency power supply is also used to reduce the cost. A plurality of electrode units 5 are connected to 8 in parallel and lit. In this case, the same voltage is applied to the plurality of electrode units 5 to start discharging.

However, even if the same voltage is applied between the electrodes 2 and 3, due to a minute difference in the distance between the electrodes 2 and 3 of each electrode unit 5, a minute difference in the thickness of the dielectric 4, and the like, The voltage applied to each will be different. That is, even if the same voltage is applied to each of the plurality of electrode units 5, an electrode unit 5 that starts discharging and an electrode unit 5 that does not start discharging are generated.
In order to efficiently generate excimer molecules by discharge, a gas pressure of several tens of kPa is preferable. However, at such a gas pressure, when discharge starts at a certain electrode unit 5, a voltage at which discharge starts (discharge start) The voltage during discharge (discharge sustaining voltage) is lower than the voltage). As a result, when a plurality of electrode units 5 are connected in parallel to the high-frequency power source 8, when a discharge starts in a certain electrode unit 5, the voltage applied to the electrode unit 5 that has not yet started discharging decreases. Will end up. Therefore, the problem that discharge cannot be started about all the electrode units 5 arises.

In order to cope with such a problem, it is possible to suppress the occurrence of the above-described problem by increasing the voltage applied to each electrode unit 5, but applying a high voltage is not possible for a high-frequency power supply. This is accompanied by an increase in size, which is disadvantageous in terms of cost.
Even if a metal auxiliary electrode is installed between the electrodes to reduce the discharge start voltage, there is an effect of reducing the discharge start voltage, but since the discharge is concentrated near the auxiliary electrode, a uniform illuminance distribution You will not be able to get.

  In view of the above problems, an object of the present invention is to provide an excimer light irradiation apparatus capable of starting discharge simultaneously for all of the electrode units even when a plurality of electrode units are connected in parallel to a high-frequency power source. There is.

The present invention employs the following means in order to solve the above problems.
The first means is that an electrode unit comprising an inner electrode, an outer electrode provided around the inner electrode, and a dielectric provided on at least one of the two electrodes is an excimer light generator. In an excimer light irradiation apparatus arranged adjacent to each other in a gas-filled casing, an excimer light irradiation apparatus is characterized in that an opening communicating with a discharge space is formed in an outer electrode of the adjacent electrode unit. .

  A second means is an excimer light irradiation apparatus according to the first means, wherein the inner electrode is made of a rod-like body and the outer electrode is made of a cylindrical body.

  According to a third means, in any one of the first means and the second means, the pressure of the excimer light generating gas filled in the casing is 10 kPa or more, and the outside of the adjacent electrode unit The excimer light irradiation apparatus is characterized in that the distance between the openings of the electrodes is 10 mm or less.

  According to the excimer light irradiation apparatus of the present invention, even when a plurality of electrode units are connected in parallel to a high-frequency power source and the same voltage is applied to each electrode unit, excimer discharge is generated in the discharge spaces of all the electrode units. Can be generated. Further, since it is not necessary to apply an excessively high voltage, it is not necessary to increase the size of the high-frequency power source. And the problem that the electrode unit in which excimer discharge is formed and the electrode unit in which excimer discharge is not formed, which has been a problem in the conventional excimer light irradiation apparatus, can be solved well.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a front cross-sectional view of an excimer light irradiation apparatus according to the invention of the present embodiment, and FIG. 2 is a main part cross-sectional view as seen from AA ′ of the excimer light irradiation apparatus shown in FIG.
The excimer light irradiation apparatus 100 includes a housing 1, an electrode unit 5 including an outer electrode 2, an inner electrode 3, and a dielectric 4, a light emission window 6 fitted and fixed in an opening of the housing 1, It comprises a metal member 7 for controlling the gas flow and a high frequency power source 8 electrically connected to the electrode unit 5.

  The housing 1 is made of stainless steel and filled with argon gas as an excimer light generating gas. The filling pressure of argon gas is 10 kPa to 1000 kPa, for example, 50 kPa. Argon gas is introduced into the housing 1 from the gas inlet 10 provided in the housing 1 at a flow rate of 1 liter (L) / min and discharged from the gas exhaust port 11. That is, by preventing the excimer light generating gas from excessively raising the temperature by causing the excimer light generating gas to recirculate inside the housing 1, the excimer light generation efficiency associated with the high temperature of the excimer light generating gas can be improved. The decline is prevented.

  When argon gas is used as the excimer light generating gas, argon excimer light having a center wavelength of 126 nm is generated. In addition, xenon gas and krypton gas can be used. These mixed gases can also be used. That is, excimer light having a wavelength corresponding to the application can be generated by selecting the type of gas or adjusting the mixing ratio of the gas.

In the electrode unit 5, the inner electrode 3 made of a metal rod is covered with a tubular dielectric body 4, and the outer electrode 2 made of a tubular body is arranged on the substantially central axis thereof. The dielectric 4 is arranged so as to be separated from the dielectric 4. The spaces between the outer electrode 2 and the dielectric 4 are discharge spaces Sa, Sb.
The outer electrode 2 is made of, for example, copper, and the inner electrode 3 is also made of, for example, copper. The dielectric 4 is made of alumina, for example.

Each outer electrode 2 in each electrode unit 5 is formed with an opening 22 so that the discharge spaces Sa and Sb of the adjacent electrode units 5a and 5b communicate with each other. The opening 22 is formed by providing a through hole in the body 21 of the outer electrode 2 made of a cylindrical body, and various shapes such as a round shape and a square shape can be adopted. The opening 22 may be provided at any location on the body 21 of the outer electrode 2 or a plurality of openings 22 may be provided. That is, the outer electrode 2 may be formed of a mesh-like cylindrical body, or the opening may be formed by means such as providing a slit in the outer electrode 2.
A plurality of such electrode units 5 are arranged adjacent to each other inside the housing 1. Here, “adjacent” means a state in which the electrode units 5 are in contact with each other, or a state in which the electrode units 5 are separated with a small space interposed therebetween.

  In addition, in the separated form, when the filling pressure of the excimer light generating gas in the housing 1 is 10 kPa or more, as will be described later, it is ensured that the electrode unit 5 that has not started the discharge is reliably charged with electrons or light. The distance between the openings 22 in the opposing outer electrode 2 of the adjacent electrode unit 5 is preferably 10 mm or less, particularly preferably 3 mm or less. Here, the “separation distance” refers to the shortest distance between the adjacent openings 22.

The light exit window 6 is made of, for example, calcium fluoride (CaF ₂ ), but may be any one that transmits argon excimer light (wavelength range of 110 nm to 150 nm). The metal member 7 is an annular metal plate (aluminum, thickness 5 mm), and has a shape that closes between the outer peripheral portion of the electrode unit 5 disposed on the outside and the inner wall of the housing 1.

Here, numerical examples relating to the excimer light irradiation apparatus according to the invention of the first embodiment will be shown. However, the present invention is not limited to the following numerical examples.
The housing 1 has a rectangular parallelepiped shape, and is 100 mm long, 100 mm wide, and 120 mm high. The outer electrode 2 has a cylindrical shape, and has an outer diameter of 14.5 mm, a wall thickness of 0.5 mm, and a total length of 30 mm. The opening 22 is circular and has a diameter of 1 mm to 3 mm, for example, 2 mm. The inner electrode 3 has a cylindrical shape and has an outer diameter of 2 mm and a total length of 65 mm. The dielectric 4 has a cylindrical shape and has an outer diameter of 4 mm, a wall thickness of 1 mm, and a total length of 60 mm. The discharge distance L between the outer electrode 2 and the dielectric 4 is 4.8 mm.
The voltage applied to both electrodes 2 and 3 by the high frequency power supply 8 is in the range of 1 kV to 10 kV, for example, 4 kV.

  In the excimer light irradiation apparatus 100 according to the invention of the present embodiment, when a plurality of electrode units 5 are connected in parallel to the high-frequency power source 8 and the same voltage is applied to each electrode unit 5, all the electrode units 5 There is an effect that excimer discharge is formed in the discharge space. And since it is not necessary to apply an excessively high voltage, a power supply does not enlarge. That is, it is possible to satisfactorily solve the problem that an electrode unit in which excimer discharge is formed and an electrode unit in which no excimer discharge is mixed, which has been a problem in the conventional excimer light irradiation apparatus.

The reason will be described with reference to FIGS.
FIG. 3 is a diagram showing the behavior of electrons, atoms, etc. in the discharge space when a high frequency voltage is applied.
As shown in the figure, when a high-frequency voltage is applied to the discharge space, electrons that have gained energy from the applied voltage collide with the atoms of the discharge gas, so that the atoms subjected to the electron collision are divided into electrons and ions. The electrons generated in this manner obtain energy from the applied voltage, and the above behavior is repeated, whereby the number of electrons and ions is increased and discharge is generated. That is, the excimer light irradiation apparatus according to the invention of the present embodiment easily generates a discharge due to a decrease in the discharge start voltage by increasing the total number of electrons and ions present in the discharge space of the electrode unit. It pays attention to.

FIG. 4 is an enlarged view showing a configuration in the vicinity of the opening 22 of the adjacent outer electrode 2 when a high frequency voltage is applied from the high frequency power supply 8 to each electrode unit 5.
As shown in the figure, by connecting the discharge spaces Sa and Sb of the adjacent electrode units 5a and 5b through the opening 22 provided in the outer electrode 2, the ultraviolet light emitted from the electrode unit 5a in which discharge has started. Electrode unit 5b where light, visible light, electrons, ions, excited atoms and metastable excited atoms pass through opening 22 of outer electrode 2 and electrode unit 5a adjacent to electrode unit 5a where discharge has started has not started Is introduced into the discharge space Sb.
When the outer electrode 2 or the dielectric 4 is irradiated with ultraviolet light or visible light, electrons are emitted from these surfaces. In particular, since ultraviolet light such as excimer light has high energy, electrons are easily emitted when the ultraviolet light is applied to the outer electrode 2 or the like. Electrons are also emitted when particles having energies such as ions, excited atoms, and metastable excited atoms collide with the outer electrode 2 or the surface of the dielectric 4.
In addition to the electrons and ions introduced into the electrode unit 5b where the discharge has not started, the newly released electrons are added, so that the discharge start voltage of the electrode unit 5b where the discharge has not started is easily reduced. The discharge can be started.

  As a result, according to the excimer light irradiation apparatus 100 according to the invention of the present embodiment, when a plurality of electrode units 5 are connected in parallel to one high-frequency power supply 8 and the same voltage is applied to each electrode unit 5 In this case, excimer discharge can be generated in the discharge spaces S of all the electrode units 5.

  The outer electrode 2 is a cylindrical body having openings at both ends, and the discharge spaces Sa and Sb of the adjacent electrode units 5a and 5b are connected through the openings at both ends. However, the ultraviolet light or visible light generated in the electrode unit 5a where the above discharge has started passes through the openings at both ends and enters the discharge space Sb of the electrode unit 5b adjacent to the electrode unit 5a where the discharge has not started. Never reach. Further, since the excimer light generating gas flows in the discharge spaces Sa and Sb of the electrode units 5a and 5b, the particles such as the above-described excited atoms stay at both ends of the outer electrode 2 until the gas flows. It is not introduced into the discharge space Sb of the electrode unit 5b where discharge has not started through the opening. Because of such circumstances, the technical significance of the present invention is that the opening 22 is intentionally provided in the body 21 of the outer electrode 2 made of a cylindrical body.

Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 5 is a front cross-sectional view of the excimer light irradiation apparatus according to the invention of the present embodiment, and FIG. 6 is a main part cross-sectional view of the excimer light irradiation apparatus shown in FIG.
5 and 6 correspond to the configurations of the same reference numerals shown in FIGS. 1 and 2, and detailed description thereof will be omitted.

  In the excimer light irradiation apparatus 200 shown in FIGS. 5 and 6, a coating layer 9 made of a dielectric material such as alumina is formed over the entire surface of the outer electrode 2 on the side facing the inner electrode 3. The thickness of the coating layer 9 is 0.5 mm to 2 mm, for example, 1 mm. A covering tube 23 made of a cylindrical body is inserted into the openings 22a and 22b facing each other between the adjacent electrode units 5a and 5b, and the covering layer 9 and the covering tube 23 are bonded and fixed by a ceramic adhesive. Yes.

  According to the excimer light irradiation apparatus 200 according to the invention of the present embodiment, in addition to the excimer light irradiation apparatus according to the invention of the first embodiment, the surface of the outer electrode 2 facing the inner electrode 3 is made of a dielectric. By providing the covering layer 9, the electric field is uniform on the surface of the covering layer 9 and the discharge is uniformly generated, so that a uniform illuminance distribution can be obtained.

The reason is considered as follows. That is, the surface of the outer electrode 2 made of metal is not flat when viewed microscopically, and may have minute irregularities. As a result, when a high-frequency voltage is applied between the electrodes 2 and 3, the electric field generated on the surface of the outer electrode 2 is concentrated on the convex portion, so that a sparse discharge is generated between the electrodes 2 and 3. This is because the illuminance distribution may be impaired.
However, according to the excimer light irradiation apparatus 200 according to the invention of the present embodiment, since the coating layer 9 made of a dielectric is provided on the surface of the outer electrode 2 facing the inner electrode 3, Since the electric field is uniform on the surface, the discharge occurs uniformly. Thereby, uniform illumination distribution can be obtained.
Furthermore, it is possible to prevent the electrode unit 5 from being damaged due to local heating due to the concentration of discharge.

In each of the above embodiments, an example in which a plurality of electrode units are electrically connected to one high-frequency power source and are lit in parallel has been described. However, the present invention is not limited to this.
This is because even when one electrode unit is connected to one high-frequency power supply, it is disadvantageous in terms of cost to apply an excessively high voltage more than necessary at the time of starting. This is because it is advantageous in terms of cost to apply only substantially equal voltages. That is, the present invention can naturally be applied to a form in which one high-frequency power source is electrically connected to one electrode unit and is lit.

It is front sectional drawing of the excimer light irradiation apparatus which concerns on invention of 1st Embodiment. It is principal part sectional drawing seen from A-A 'of the excimer light irradiation apparatus shown in FIG. It is a figure which shows the behavior of an electron, an atom, etc. in the discharge space when a high frequency voltage is applied. FIG. 3 is an enlarged view showing a configuration in the vicinity of an opening 22 of an adjacent outer electrode 2 when a high frequency voltage is applied to each electrode unit 5 from a high frequency power supply 8. It is front sectional drawing of the excimer light irradiation apparatus which concerns on invention of 2nd Embodiment. It is principal part sectional drawing seen from B-B 'of the excimer light irradiation apparatus shown in FIG. It is front sectional drawing of the excimer light irradiation apparatus which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing | casing 2 Outer electrode 21 Body part 22,22a, 22b Opening part 23 Clad tube 3 Inner electrode 4 Dielectric 5,5a, 5b Electrode unit 6 Light emission window 7 Metal member 8 High frequency power supply 9 Covering layer 10 Gas inlet 11 Gas exhaust port 100 Excimer light irradiation device 200 Excimer light irradiation device Sa, Sb Discharge space

Claims (3)

An electrode unit comprising an inner electrode, an outer electrode provided around the inner electrode, and a dielectric provided on at least one of the two electrodes has a casing filled with an excimer light generating gas. In the excimer light irradiation device arranged adjacent to the body,
An excimer light irradiation apparatus, wherein an opening that communicates a discharge space is formed in an outer electrode of the adjacent electrode unit.   The excimer light irradiation apparatus according to claim 1, wherein the inner electrode is made of a rod-like body, and the outer electrode is made of a cylindrical body.   The pressure of the excimer light generating gas filled in the housing is 10 kPa or more, and the separation distance between the openings of the outer electrodes of the adjacent electrode units is 10 mm or less. Item 3. The excimer light irradiation apparatus according to Item 2.

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