JP4158705B2 - Excimer light irradiation equipment - Google Patents

Description

  The present invention relates to an apparatus for irradiating excimer light by excimer discharge. In particular, the present invention relates to an excimer light irradiation apparatus for the purpose of uniformly irradiating a large area with high output.

In recent years, a sterilization apparatus using excimer light, a liquid crystal substrate cleaning apparatus, a resin curing apparatus, and the like are known. As the excimer light source, an excimer discharge lamp is generally used. As an excimer discharge lamp, for example, a cylindrical lamp vessel made of, for example, quartz glass is provided with an outer electrode and an inner electrode on the outside and inside, respectively, and an excimer-generating gas is sealed inside the lamp vessel ( For example, see Japanese Patent Publication No. 7-87093). In the excimer discharge lamp, electric energy is supplied from the outside to the outer electrode and the inner electrode, whereby discharge occurs in the lamp vessel, and excimer light is generated by the excimer generation gas.
Moreover, as an excimer light irradiation apparatus equipped with such an excimer discharge lamp, for example, a structure disclosed in Japanese Patent Application Laid-Open No. 11-183699 is known.

  However, according to the excimer light irradiation apparatus as described above, the lamp vessel of the excimer discharge lamp as the light source is made of quartz glass, and the quartz glass constituting the lamp vessel deteriorates with the lapse of the lamp lighting time, and excimer light Therefore, it is difficult to maintain a desired illuminance for a long time. In recent years, in the aforementioned sterilizer, liquid crystal substrate cleaning device, resin curing device, etc., the power input to the excimer lamp has been increased to increase the output of the excimer lamp in order to reduce the cost by increasing the process speed. Therefore, the deterioration of the quartz glass constituting the lamp vessel is remarkable.

  Further, there is a problem that the excimer generation gas is contaminated by the impurity gas generated in the lamp vessel by the excimer light irradiation, and the light output of the excimer light decreases with time. More specifically, when the lamp vessel or the excimer light transmission window is made of a material that releases oxygen gas by being exposed to excimer light such as quartz glass, the oxygen gas released as the impurity gas is the excimer gas. It absorbs light strongly and significantly reduces the light output of excimer light.

  In order to solve the above problem, in an excimer light irradiation apparatus in which a plurality of pairs of electrodes are arranged in a stainless steel casing with a dielectric interposed therebetween, the excimer light generating rare gas filled in the casing is replaced. A method is known (see, for example, JP-A-2001-148233). Hereinafter, the structure described in this publication will be described with reference to FIG.

FIG. 9 is a longitudinal sectional view for explaining a conventional excimer light irradiation apparatus equipped with a rare gas replacement method.
The excimer light irradiation device 90 includes a casing 91, a cylindrical dielectric 92, and a rod-shaped electrode 93 that is fitted on the inner surface of the dielectric 92 and faces the dielectric 92. In the housing 91, a light extraction window 95 is incorporated in an opening provided in the light emitting direction 200, and a gas inlet 96 for sucking and exhausting a rare gas as an excimer discharge generated gas introduced into the housing 91. A gas discharge port 97 is provided. The rare gas in the housing 91 can be replaced by the gas inlet 96 and the gas outlet 97. In the housing 91, by applying a high frequency high voltage to the opposing electrode 93 by an external circuit (not shown), an excimer discharge is formed between the opposing electrodes 93, thereby forming a discharge portion 98, and noble gas excimer light is generated. Radiated.

According to the structure shown in FIG. 9, since the lamp vessel made of quartz glass is not required unlike the excimer light irradiation device on which the excimer discharge lamp is mounted, the service life can be greatly extended. Further, even if the dielectric 92 and the light extraction window 95 are made of quartz glass, the rare gas in the housing 91 can be always replaced, so that the generated oxygen is discharged out of the housing 91 together with the rare gas, and impurities There is no gas problem.
Japanese Patent Publication No. 7-87093 JP 11-183699 A JP 2001-148233 A

  However, when an excimer light irradiation device was manufactured according to the structure shown in FIG. 9 and a lighting test was performed, the problem of impurity gas does not occur, but unevenness in illuminance occurs in the light irradiated from the excimer light irradiation device. It has been found that there is a problem that a uniform illuminance distribution cannot be obtained on a surface irradiated with (also referred to as a surface to be processed).

The present inventors diligently studied the cause of the above illuminance unevenness, and ascertained that one of the main causes is a gap between the electrode and the dielectric. This will be specifically described below.
In the excimer light irradiation apparatus shown in FIG. 9, a rod made of, for example, aluminum used as the electrode 93 or a tube made of, for example, quartz glass, used as the dielectric 92 has a dimensional error during its manufacture. As a specific example, the case where a rod made of aluminum is used as an electrode will be described below with reference to FIG.

  FIG. 10 is a diagram for explaining an aluminum bar 93 that serves as an electrode having a dimensional error. Even if the standard of the aluminum rod 93 is, for example, 10 mm in diameter, as shown in FIG. 10, the diameter X1 at one end is 9.8 mm, the diameter X2 at the center is 10.2 mm, and the other end is There is an error from the standard value at each part such that the diameter X3 is 10 mm. Such an error from the standard value is called a dimensional error. In the example of FIG. 10, a dimensional error of ± 2% is generated. Although not shown here, the above dimensional error naturally occurs also in the quartz glass tube 92 which should be a dielectric for covering the periphery of the aluminum rod 93. Therefore, when the aluminum rod 93 which becomes an electrode is inserted into the quartz glass tube 92 which becomes such a dielectric, a gap is generated between the two. The discharge state when a gap is generated between the electrode and the dielectric will be described below with reference to FIG.

FIG. 11 is a diagram for explaining the state of excimer discharge when there is a gap between the electrode and the dielectric. As shown in FIG. 11, when the aluminum rod 93 serving as an electrode is fitted inside the quartz glass tube 92 serving as a dielectric, the inner diameter of the quartz glass tube 92 and the outer diameter of the aluminum rod 93 have a dimensional error. A gap portion is formed between the aluminum rod 93 and the quartz glass tube 92 that is not in contact, and almost no discharge is formed in this portion. On the other hand, in the portion where the aluminum rod 93 and the quartz glass tube 92 are in contact, the above phenomenon does not occur and a discharge is formed.
As a result, in the excimer light irradiation apparatus shown in FIG. 9, when a plurality of electrodes and dielectrics are inserted with a gap between them, the illuminance is applied to the light emitted from the excimer light irradiation apparatus. It is thought that unevenness occurs.

Here, the reason why the discharge hardly occurs in the portion where the metal rod serving as the electrode is not in contact with the dielectric tube will be described. When a voltage V is applied between one electrode 1 and the other electrode 2 covered with the dielectric 3 as shown in FIG. 12, on the dotted line A where the other electrode 2 and the dielectric 3 are in close contact with each other. The capacitance of the dielectric 3 is C ₁ , the capacitance of the discharge space 6 between the dielectric 3 and one electrode 1 is C _2, and one surface 4 of the dielectric 3 and the other electrode 2 are V _{1 is} the voltage between and V ₂ is the voltage in the discharge space 6. The capacitance of the gap 7 between the other electrode 2 on the dotted line B where the other electrode 2 and the dielectric 3 are not in close contact with each other surface 5 of the dielectric ₃ is C ₃ , and the dielectric 3 The voltage between one surface 4 and the other electrode 2 is V ₁ ′, and the voltage in the discharge space 6 is V ₂ ′. If the capacitance of the space to which V ₁ ′ is applied is C ₁ ′, C ₁ ′ is expressed as follows.

V ₁ , V ₂ , V ₁ ′, V ₂ ′ are expressed as follows.

Since the width of the gap 7 is smaller values of larger the _{C 3,} equation (1) (3) (5) from _{C 1} 'value of decreases, _{V 1'} the value of the increases, the _{V 2} ' The value becomes smaller. Conversely to the value of about C ₃ width of the gap is small is increased, C 1 _'value of approaches to the value of C _1, if there are no intervals of the gap, C _1' for a = C _1, V ₁ '= V ₁ and V ₂ ′ = V ₂ . That is, V ₂ ′ becomes smaller than V ₂ as the gap interval increases.
From the above, as shown in FIG. 11, if there is a gap when the aluminum rod 93 is inserted into the quartz glass tube 92, the voltage applied to the discharge space is reduced compared to the case where both are in close contact with each other. Is not expected to occur.

  In order to solve the above problems, in order to minimize the portion that is not in contact between the electrode and the dielectric, a rod that becomes an electrode with a small dimensional error from the standard value and a tube that becomes a dielectric are used. A method is conceivable. However, a rod or tube with a small dimensional error is very expensive, so it is not a practical method in consideration of cost.

  Accordingly, the problem to be solved by the present invention is that in an excimer light irradiation apparatus that forms excimer discharge between electrodes that are arranged to face each other through a dielectric in a casing filled with excimer-generating gas, the electrode and the dielectric By increasing the contact area, the excimer discharge can be satisfactorily performed, and the illuminance unevenness of the irradiated light can be eliminated and the illuminance distribution on the surface to be processed can be made uniform.

  In order to solve the above-mentioned problems, an excimer light irradiation device according to the present invention includes a housing having a light extraction window in the light emitting direction and an electrode disposed in the housing and facing each other through a dielectric, and faces each other. Excimer discharge is generated between the electrodes, and at least one of the opposing electrodes and the dielectric have screw portions, and are screwed together by the screw portions.

  According to the excimer light irradiation apparatus of the present invention, either one of the opposing electrodes and the dielectric have screw portions, and both are screwed by each screw portion. As a result, even if the electrode and the dielectric have some dimensional errors with respect to the standard value, the contact area increases when the screw portions come into contact with each other, and the portion where no discharge is formed can be reduced. . Therefore, it is possible to obtain a uniform illuminance distribution on the surface to be processed without causing illuminance unevenness in the irradiated light, and furthermore, the dimensional error with respect to the standard value is extremely small for the members constituting the electrode and the dielectric. This is advantageous in terms of cost.

FIG. 1 is a diagram for explaining an excimer light irradiation apparatus according to the present invention. FIG. 1A is a cross-sectional view in the longitudinal direction, and FIG. 1B is a view of a plate-like electrode arranged in a case described later shown in FIG.
As shown in FIG. 1A, an excimer light irradiation device 10 includes a casing 11, one rod-shaped electrode 13 disposed in the casing 11 and opposed via a cylindrical dielectric 12, and a plate-shaped electrode 13. And the other electrode 14. The arrangement of the dielectric 12, the one electrode 13, and the other electrode 14 will be described in detail. As shown in FIG. 1B, each of the 30 to 300 through holes 20 provided in the other electrode 14. The dielectric 12 is disposed so as to contact the surface, and one electrode 13 is inserted so as to be concentrically disposed in the through hole 20. That is, one electrode 13 and the other electrode 14 are opposed to each other with the tubular dielectric 12 interposed therebetween.

  The housing 11 is provided with a light extraction window 15 at an opening provided in the light emission direction 200, a gas suction port 16 and a gas discharge port 17, and 5 to the light extraction window 15. A support base 18 for supporting the plate-like electrode 14 is attached so as to have an interval of about 20 mm. By having an interval, the gas can easily flow between the one electrode 13 and the other electrode 14 when the excimer generating gas is refluxed into the housing. However, if the interval is too large, the discharge unit 19 is further away from the light extraction window 15, and therefore the interval is preferably about 5 to 20 mm. The casing 11 is filled with, for example, xenon gas as an excimer discharge generation gas through the gas suction port 16 so that the pressure in the casing 11 becomes 40 kPa, and the one electrode 13 and the other electrode 14 facing each other are filled. By applying a high frequency high voltage of, for example, a voltage of 3 kV and a frequency of 50 kHz in an external circuit (not shown), a discharge portion 19 is formed by excimer discharge, and xenon excimer light having a wavelength of 172 nm is emitted.

  In the case 11, the excimer discharge generated gas is refluxed. More specifically, the gas sucked from the gas suction port 16 contributes to the formation of the discharge part 19 and is then discharged out of the housing 11 through the gas discharge port 17. As the excimer discharge generated gas that circulates in the housing 11, in addition to the above xenon gas, argon gas, krypton gas, or the like can be used. These gases are not limited to simple substances, and may be used as a mixed gas. Furthermore, a mixed gas of a halogen gas and one of the above gases can also be used as long as the safety problem can be solved.

  FIG. 2 shows an enlarged view of a dotted line portion A in FIG. FIG. 3 is an enlarged view of a dotted line portion B in FIG.

  As shown in FIG. 2, the dielectric 12 has a screw portion 120 formed on the surface thereof screwed into a screw portion 140 formed on the surface of the through hole 20 provided in the other electrode 14. Therefore, it is held by the other electrode 14. As shown in FIG. 3, the screw portion 120 includes a convex portion 121 and a concave portion 122, a top portion 123 is formed at the tip of the convex portion 121, and a bottom portion 124 is formed at the bottom of the concave portion 122. The screw portion 140 includes a convex portion 141 and a concave portion 142, and a top portion 143 is formed at the tip of the convex portion 141, and a bottom portion 144 is formed at the bottom of the concave portion 142. As the screw part 120 and the screw part 140 are screwed together, the convex part 121 and the convex part 141 come into contact at a plurality of locations.

With the above configuration, the contact area between the dielectric 12 and the other electrode 14 can be increased, so that excimer discharge can be satisfactorily formed. In addition, since the dielectric 12 and the other electrode 14 are screwed together and held, it is possible to hold them more firmly than simply fitting them together, so that vibration or impact is applied to the housing 11. However, there is no possibility of causing an illuminance change due to a deviation from the optimum position. Further, for example, in a method in which an aluminum rod serving as one electrode 13 is inserted into a quartz glass tube serving as a dielectric 12, if there is a dimensional error between the quartz glass tube and the aluminum rod, the quartz glass tube is forcedly inserted into the quartz glass tube. There is a risk of cracking. On the other hand, in the configuration of the present invention, there is little such fear, and there is an advantage that the excimer light irradiation apparatus 10 can be easily manufactured.
The dielectric 12 has a plate-like length in order to prevent a discharge not passing through the dielectric 12 between the one rod-like electrode 13 and the other plate-like electrode 14. The electrode 14 is preferably longer than the thickness of the electrode 14. Specifically, it is particularly preferable that both ends of the dielectric 12 are about 5 to 20 mm longer than the other electrode 14.

Hereinafter, the casing 11, the light extraction window 15, the dielectric 12, the one electrode 13, and the other electrode 14 will be described in detail.
The casing 11 is composed of a cylindrical box made of stainless steel, and has an outer diameter of 200 mm to 600 mm, a height of 200 mm to 600 mm, and a wall thickness of 3 to 5 mm. Of course, not only a cylinder but also a box whose section obtained by cutting along the XZ plane is a polygon such as a rectangle can be used. The Z-axis direction is not shown in FIG. 1A, but is perpendicular to the paper surface.
The light extraction window 15 is made of a quartz glass disk and has a diameter of 100 to 400 mm and a thickness (Y-axis direction) of 5 to 30 mm. Of course, the plate is not limited to a circular plate, and may be a plate whose cross section obtained by cutting along the XZ plane is a polygon such as a rectangle. The material of the light extraction window 15 is not limited to quartz glass, and sapphire, magnesium fluoride (MgF ₂ ), or the like can be used. According to the light irradiation device 10 of the present invention, since it has a function of recirculating the gas in the housing 11, a material that releases oxygen gas when exposed to excimer light such as quartz glass or sapphire is used as a light extraction window. 15 can be suitably used.

The dielectric 12 is made of, for example, a ceramic cylinder, and has an outer diameter of 5 to 30 mm, a total length of 10 to 120 mm, and a thickness of 1 to 5 mm. Of course, not only a cylinder but also a cylinder whose section obtained by cutting along the XZ plane is a polygon such as a rectangle may be used. The outer peripheral surface of the dielectric 12 is threaded. The dimensions of the screw portion 120 are preferably M5 to M30 (JIS standard B 0205 metric coarse screw). The material of the dielectric 12 is not limited to ceramics, and glass or the like can be used. The following method can be considered as a method of forming the screw part 120 in the dielectric 12. When it is formed on the outer peripheral surface of the dielectric 12, it is cut by a lathe, and when it is formed on the inner peripheral surface of the dielectric 12 as shown in FIG. The ceramic can be molded and fired in a state where the screw portion is formed. Further, when a material called machinable ceramics that can be easily machined is used, the screw portion can be easily formed. The ceramics, alumina _{(Al 2 O} 3), mullite _{(3Al 2 O 3, 2SiO 2} ), steatite (MgO, SiO ₂₎ can be used. As the machinable Brucella mix, sintering the fluorine mica or Those using molten mica ceramics or those using aluminum titanate ceramics, aluminum nitride ceramics, or the like can be used.

One electrode 13 is made of, for example, an empty rod having an outer diameter of 1 to 5 mm and a total length of 5 to 150 mm, or a hollow cylinder. Of course, not only a cylinder but also a cylinder having a polygonal cross section obtained by cutting along the XZ plane can be used.
The other electrode 14 is made of, for example, a disk made of aluminum and having an outer diameter of 50 to 400 mm and a thickness of 5 to 100 mm. Of course, it is not limited to a circular plate, but may be a plate having a rectangular parallelepiped shape. The other electrode 14 is provided with through-holes 30 to 300 which are threaded to insert the one electrode 13 concentrically and to be screwed into a screw portion 120 formed in the dielectric 12. Individually formed. The dimension of the through hole 20 is preferably M5 to M30 (JIS standard B 0205 metric coarse screw). The material of the one electrode 13 and the other electrode 14 is not limited to aluminum, but copper, brass, and stainless steel are preferable. In particular, copper is preferable because of its high thermal conductivity and easy cooling of the electrode.

  FIG. 4 is a cross-sectional view of a main part for explaining another screwing form of the dielectric and the electrode. In the excimer light irradiation apparatus 10 of the present invention, as shown in FIG. 4, a screw portion 120 and a dielectric 12 and a rod-like electrode 13 inserted into a through hole 20 formed in the other electrode 14. It is also possible to form 130.

FIG. 5 is a cross-sectional view for explaining another embodiment of the excimer light irradiation apparatus of the present invention. The same reference numerals as those in FIG. 1 denote the same parts.
Excimer light irradiation apparatus 50 is substantially the same in structure as excimer light irradiation apparatus 90 shown in FIG. 9 except that cylindrical dielectric 52 and rod-shaped electrode 53 have screw portions. Omitted. In the light irradiation device 50, a high frequency high voltage is applied to the opposing electrode 53 by an external circuit (not shown), and excimer discharge is generated between the opposing electrodes 53, thereby forming a discharge portion 59 having a wavelength of 172 nm. Xenon excimer light having
In FIG. 5, the dielectrics 52 are provided on all the electrodes 53, but the structure is not limited to this structure. In short, the dielectrics 52 may be provided on at least one side of the opposing electrodes 53.

FIG. 6 shows a cross-sectional view when the dotted line portion C in FIG. 5 is cut along the XZ plane.
Although not shown in FIG. 5, the Z-axis direction is a direction perpendicular to the paper surface.
The dielectric 52 is made of, for example, a ceramic tube, and has a screw portion 520 on the surface thereof. The electrode 53 is made of, for example, a non-empty rod made of aluminum, and has a screw portion 530 on the outer surface thereof, like the dielectric 52. The dielectric 52 and the electrode 53 are screwed into the screw portions 520 and 530 so that the convex portion 521 and the convex portion 531 are in contact at a plurality of locations.

Hereinafter, an experiment showing the effect of the light irradiation apparatus of the present invention will be described. First, the excimer light irradiation apparatus used in the experiment will be described.
<Light irradiation apparatus of the present invention>
Enclosure:
Gas sealed in a stainless steel cylindrical container housing having an outer diameter of 560 mm, a height of 200 mm, a wall thickness of 5 mm, and an inner volume of 47500 cm ³ :
Xenon gas at 50 KPa
Light extraction window:
A dielectric plate made of synthetic quartz glass having a diameter of 400 mm and a thickness of 20 mm:
An electrode having an outer diameter of 20 mm, an inner diameter of 15 mm, and a total length of 40 mm provided with an M20 screw on the outer peripheral surface. One electrode:
Non-empty aluminum rod with an outer diameter of 3 mm and a total length of 80 mm The other electrode:
An aluminum plate having an outer diameter of 450 mm and a thickness of 30 mm provided with 271 through-holes having M20 screw portions <light irradiation device of a comparative example>
Except for the point that the electrode does not have a screw portion, the other configuration is the same as that of the light irradiation apparatus of the present invention.

<Measurement method of illuminance>
Next, an experimental method using the excimer light irradiation apparatus of the present invention and a comparative example will be described. FIG. 7 is a diagram for explaining an illuminance measurement method for the light irradiation apparatus of the present invention and a comparative example.
About the light irradiation apparatus of this invention and a comparative example, it lights on the conditions of 3 kV and 50 KHz, and is 10 mm away from the light extraction window 15 attached to the housing | casing 11 to the Y-axis direction as shown in FIG. The illuminance of excimer light having a wavelength of 172 nm emitted from the light irradiation device 10 was measured by the illuminance measurement device 40. Specifically, the light receiver 41 provided in the illuminance measuring device 40 moves the light receiver 41 by 20 mm from one end 151 to the other end 152 of the light extraction window 15 at each position. The illuminance was measured. That is, assuming that the center position of the light extraction window 15 (intersection of diagonal lines) is X = 0 and Z = 0, when the length in the X-axis direction is 460 mm, one end 151 is set to X = −230. Assuming that a position 20 mm away from the end 151 in the X-axis direction is X = −210 and the other end is X = 230, (X, Z) = (− 230, 0), (−210, 0) ) ... Illuminance is measured at a total of 24 locations of (230, 0).

<Experimental result>
Finally, the experimental results will be described. FIG. 8 is a diagram showing the illuminance measured by the light irradiation apparatus of the present invention and a comparative example. □ shown in FIG. 8 indicates data in the light irradiation apparatus of the present invention, and ■ indicates data in the light irradiation apparatus of the comparative example.
According to FIG. 8, the light irradiation device of the comparative example has a large variation in illuminance in the region of X = −90 to 150, whereas the light irradiation device of the present invention has a variation in illuminance in the region of X = −90 to 150. You can see that it is suppressed. Therefore, the light irradiation apparatus of the present invention can make the illuminance distribution uniform on the irradiated surface as compared with the light irradiation apparatus of the comparative example.

  The light irradiation apparatus of the present invention as described above has a structure in which any one of the opposing electrodes and the dielectric are provided with a screw portion, and any one of the electrodes and the dielectric are screwed together. As a result, even if the electrode and the dielectric have a slight dimensional error with respect to the standard value, a portion that does not generate discharge may be formed when the screw portions formed in each contact with each other. Absent. Therefore, it is possible to obtain a uniform illuminance distribution on the surface to be processed without causing illuminance unevenness in the irradiated light, and furthermore, the dimensional error with respect to the standard value is extremely small for the members constituting the electrode and the dielectric. This is advantageous in terms of cost.

It is a figure for demonstrating the excimer light irradiation apparatus of this invention. The enlarged view of the dotted-line part A in Fig.1 (a) is shown. It is an enlarged view of the dotted line part B shown in FIG. It is sectional drawing for demonstrating the other screwing form of a dielectric material and an electrode. It is sectional drawing for demonstrating other embodiment of the excimer light irradiation apparatus of this invention. Sectional drawing at the time of cut | disconnecting the dielectric material and electrode shown in FIG. 5 by XZ plane is shown. It is a figure for demonstrating the measuring method of the illumination intensity about the light irradiation apparatus of this invention and a comparative example. It is a figure which shows the illumination intensity distribution measured with the light irradiation apparatus of this invention and the comparative example. It is a figure for demonstrating the conventional excimer light irradiation apparatus provided with the noble gas substitution method. It is a figure for demonstrating the aluminum rod used as the electrode which has a dimension error. The figure for demonstrating the mode of excimer discharge in case a clearance gap exists between an electrode and a dielectric material is shown. It is a figure for demonstrating the reason a discharge hardly arises in the part which is not contacting between the metal rod used as an electrode, and the dielectric tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light irradiation apparatus 11 Housing | casing 12 Dielectric 13 One electrode 14 The other electrode 15 Light extraction window 16 Gas inlet 17 Gas outlet 18 Support base 19 Discharge part 20 Through-hole 40 Illuminance measuring device 41 Light receiver 120 Screw part 121 Convex part 122 Concave part 123 Top part 124 Bottom part 140 Screw part

Claims (1)

In an excimer light irradiation device that includes a housing having a light extraction window in the light emitting direction and electrodes that are disposed in the housing and face each other via a dielectric, and generates excimer discharge between the facing electrodes.
An excimer light irradiation apparatus, wherein at least one of the opposing electrodes and the dielectric have screw portions and are screwed together by the screw portions.

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