JP2018156732A - Excimer lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excimer lamp in which movement of the position of the outer end of an inner electrode can be restrained, even if lighting an unlighting are repeated.SOLUTION: In an excimer lamp including a discharge container 10 of a double tube structure where an outer tube 11 and an inner tube 12 are placed coaxially, an outer electrode 30 placed on the outer peripheral surface of the outer tube 11, and an inner electrode 20 placed on the inner peripheral surface of the inner tube 12, and extending in the axial direction of the discharge container 10, where a discharge space S formed between the outer tube 11 and the inner tube 12 is filled with electric discharge gas, the inner electrode 20 consists of multiple electrode members, and in a superposition part where the ends of adjoining electrode members in the longitudinal direction are superposed, the adjoining electrode members are spot welded, and a pressing member 28 for pressing the inner electrode 20 against the inner tube 12 in the superposition part is provided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an excimer lamp used as a light source for performing surface treatment such as cleaning treatment, ashing treatment, and film formation treatment by irradiating ultraviolet rays.

  The excimer lamp is suitably used as a light source in surface treatment of an object to be processed using vacuum ultraviolet light, such as cleaning treatment, ashing treatment, and film formation treatment.

FIG. 7 is a cross-sectional view schematically showing the configuration of an example of a conventional excimer lamp.
This excimer lamp includes a discharge vessel 40 made of a dielectric. The discharge vessel 40 has a double tube structure in which a cylindrical outer tube 41 and a cylindrical inner tube 42 are arranged coaxially, and an inner peripheral surface of the outer tube 41 and an outer peripheral surface of the inner tube 42. A discharge space S is formed between the two. In the discharge space S, a discharge gas for generating an excimer that emits vacuum ultraviolet light having a wavelength of 200 nm or less is enclosed. As the discharge gas, for example, xenon gas, a mixed gas of argon and chlorine, or the like can be used.
A net-like outer electrode 45 made of a conductive material such as a wire mesh is provided on the outer peripheral surface of the outer tube 41.
An inner electrode 46 is provided in close contact with the inner peripheral surface of the inner tube 42. The inner electrode 46 is composed of, for example, two semi-cylindrical aluminum plates disposed opposite to each other across the tube axis C of the discharge vessel 40. The two aluminum plates are pressed and fixed to the inner peripheral surface of the inner tube 42 by the pressing member 48. In this excimer lamp, a plurality of pressing members 48 are provided at positions separated from each other in the axial direction of the discharge vessel 40.
The outer electrode 45 and the inner electrode 46 are connected to a high frequency high voltage power source 50, for example.
In this excimer lamp, a high-frequency and high-voltage is applied between both the outer electrode 45 and the inner electrode 46, whereby the discharge gas is discharged in the discharge space S, and vacuum ultraviolet light is emitted.
An excimer lamp having such a configuration is disclosed in Patent Document 1, for example.

JP 2001-23578 A

  Therefore, in such an excimer lamp having a double tube structure, when the lighting and extinguishing are repeated many times, the phenomenon that the outer edge position of the inner electrode 46 gradually moves from the original position occurs. It became clear. As a result, for example, in an excimer lamp in which one end of the inner tube is sealed, the inner electrode may break through the sealing portion and damage the excimer lamp.

Such a phenomenon is considered to occur by the following mechanism. That is, when the excimer lamp is turned on, the temperature of the discharge vessel 40 rises due to absorption of a part of ultraviolet rays by the glass material constituting the discharge vessel 40 and dielectric loss. When the temperature of the discharge vessel 40 rises, the temperature of the inner electrode 46 and the pressing member 48 also rises. When the temperature of the inner electrode 46 rises, the inner electrode 46 mainly extends in the length direction due to thermal expansion. Further, when the temperature of the pressing member 48 rises, the pressing member 48 extends mainly in the circumferential direction due to thermal expansion, thereby increasing the pressing force of the pressing member 48 against the inner electrode 46. However, since the plurality of pressing members 48 are not arranged at equal intervals in the axial direction for manufacturing reasons, the inner electrode 46 has a specific direction with a place where the pressing force is high as a pseudo fixed point. Will grow greatly, but not so much in the other direction. Here, the length of the inner electrode 46 in the longitudinal direction increases as the inner electrode 46 becomes longer. Further, the amount of elongation in the length direction of the inner electrode 46 also varies depending on the arrangement position of the pressing member 48.
On the other hand, when the excimer lamp is turned off, the temperature of the discharge vessel 40 starts to decrease. As the temperature of the discharge vessel 40 decreases, the temperature of the inner electrode 46 begins to decrease, and the temperature of the pressing member 48 also begins to decrease with a slight delay. When the temperature of the inner electrode 46 begins to decrease, the inner electrode 46 begins to contract mainly in the length direction. When the temperature of the pressing member 48 starts to decrease, the pressing member 48 starts to contract mainly in the circumferential direction. At this time, since the pressing force of the pressing member 48 varies as described above, the inner electrode 46 uses the place where the pressing force (friction) of the pressing member 48 is large as a pseudo fixing point. Shrink towards.
However, if the pseudo fixed point at the time of thermal expansion / contraction is displaced from the center in the axial direction, the outer edge of the inner electrode 46 does not return to the original position. As a result, when the excimer lamp is completely cooled, the position of the outer edge of the inner electrode 46 is moved outward in the length direction. At this time, all the pressing members 48 are contracted, and the pressing force of each pressing member 48 returns to the normal magnitude.
As described above, when the excimer lamp is repeatedly turned on and off, it is considered that the inner electrode moves little by little in a certain direction by the above mechanism.

  The present invention has been made based on the above situation, and provides an excimer lamp that can suppress the movement of the position of the outer edge of the inner electrode even when lighting and extinguishing are repeated. For the purpose.

The excimer lamp of the present invention includes a discharge vessel having a double tube structure in which an outer tube and an inner tube are coaxially disposed, an outer electrode disposed on an outer peripheral surface of the outer tube, and an inner peripheral surface of the inner tube. And an inner electrode extending along the axial direction of the discharge vessel, and an excimer formed by filling a discharge space in a discharge space formed between the outer tube and the inner tube A lamp,
The inner electrode is composed of a plurality of electrode members, and the adjacent electrode members are spot-welded in the overlapping portion in which the end portions in the length direction of the adjacent electrode members are overlapped,
The overlapping portion is provided with a pressing member that presses the inner electrode against the inner tube.

In the excimer lamp of the present invention, the inner electrode is composed of three or more electrode members,
The lengthwise dimension of the central electrode member in the three electrode members adjacent to each other in the axial direction of the discharge vessel is configured to be smaller than the lengthwise dimension of the other two electrode members. preferable.

  According to the excimer lamp of the present invention, the plurality of electrode members constituting the inner electrode are independently expanded and contracted at a place where the pressing force by the pressing member is high as a pseudo fixed point during thermal expansion and contraction. In addition, the amount of displacement of the outer edge of the inner electrode can be reduced. In addition, since it is only necessary that the pressing member is disposed at a position where the overlapping portion is pressed, the amount of displacement of the outer edge of the inner electrode due to variations in the pressing position of the pressing member and the pressing force of the individual pressing members. Can be prevented from changing significantly. Therefore, even if the excimer lamp is repeatedly turned on and off, it is possible to suppress the movement of the position of the outer edge of the inner electrode.

It is an axial direction sectional view showing the outline of the composition in an example of the excimer lamp of the present invention. It is sectional drawing which abbreviate | omits and shows a part in the AA line shown in FIG. It is a perspective view which shows the principal part structure in the excimer lamp shown in FIG. 1 in the state which fractured | ruptured a part of inner tube | pipe. It is sectional drawing which shows roughly the junction part of the several electrode member in an inner side electrode body. It is a figure which shows the structure in an example of a press member. It is sectional drawing which shows roughly the junction part of the several electrode member in the other structural example of an inner side electrode body. It is an axial direction sectional view showing the outline of the composition in an example of the conventional excimer lamp.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is an axial sectional view showing an outline of the configuration of an example of an excimer lamp according to the present invention. FIG. 2 is a cross-sectional view in which a part of the line AA shown in FIG. 1 is omitted. FIG. 3 is a perspective view showing a configuration of a main part of the excimer lamp shown in FIG. 1 with a part of the inner tube broken.
This excimer lamp includes a discharge vessel 10 having a double tube structure having a cylindrical discharge space S. The discharge vessel 10 is formed by joining both end portions of a cylindrical outer tube 11 and a cylindrical inner tube 12 arranged coaxially to each other by end walls 13. In this example, both ends of the inner tube 12 are open, and the inner space of the inner tube 12 in which the inner electrode 20 described later is disposed is, for example, an atmospheric atmosphere. In the excimer lamp of the present invention, one end or both ends of the inner tube 12 may be closed (sealed). Reference numeral 13a in FIG. 1 denotes a tip tube formed by sealing a fluid flow tube provided for performing surface treatment (for example, cleaning treatment) on the discharge vessel 10 and filling of discharge gas.
The discharge vessel 10 is made of a dielectric material that is transparent to excimer light (for example, light having a wavelength of 200 nm or less) emitted in the discharge vessel 10. As a dielectric material constituting the discharge vessel 10, for example, synthetic quartz glass or the like can be used.

  A discharge gas that forms excimer molecules by excimer discharge is enclosed in the discharge space S. As the discharge gas, for example, xenon gas, a mixed gas of argon and chlorine, or the like can be used.

  Further, a getter separator 16 is provided at the end of the discharge space S, and a getter chamber 15 is formed between the getter separator 16 and the end wall 13 of the discharge vessel 10. The getter chamber 15 houses a getter 18 for removing impure gas (for example, water) in the discharge space S and stabilizing the discharge. As the getter 18, for example, titanium, tantalum, an alloy of aluminum and zirconium, barium, or the like can be used.

Inside the inner tube 12 in the discharge vessel 10, an inner electrode 20 extending along the axial direction of the discharge vessel 10 is provided in close contact with the inner peripheral surface of the inner tube 12.
Further, a net-like outer electrode 30 made of a conductive material such as a wire net is provided in close contact with the outer peripheral surface of the outer tube 11 in the discharge vessel 10.
A high frequency power source (not shown) is connected to the inner electrode 20, and a high frequency high voltage is applied between the outer electrode 30 and the inner electrode 20, whereby a discharge is formed in the discharge space S.

Thus, in the above excimer lamp, the inner electrode 20 is composed of a plurality of electrode members.
The inner electrode 20 in this example is composed of, for example, three-to-six electrode members, each of which is formed such that a thin metal plate has a semicircular cross-sectional shape. More specifically, each of the inner electrodes 20 includes a pair of joined bodies (hereinafter referred to as “inner side”) in which a first electrode member 22, a second electrode member 23, and a third electrode member 24 are connected in the axial direction. It is referred to as an “electrode body”) 21, 21. In each inner electrode body 21, 21, as shown in FIG. 4, the first electrode member 22 and the second electrode member 23 are, for example, in a state where the second electrode member 23 is positioned on the inner surface side. In the overlapping portion 25 where the end portions in the length direction are overlapped, spot welding is performed, for example, by spot welding. Further, the second electrode member 23 and the third electrode member 24 are, for example, an overlapping portion 25 in which end portions in the length direction are overlapped with each other in a state where the second electrode member 23 is positioned on the inner surface side. In, for example, spot welding is performed by spot welding. In FIG. 4, a region surrounded by a broken line with a hatched line schematically shows the joint portion W of the electrode member. Here, the size L of the separation distance in the axial direction between the opposing edges of the first electrode member 22 and the third electrode member 24 is, for example, about 0.5 to 2.0 mm. Moreover, the axial direction length of the superposition part 25 is larger than the magnitude | size of the width | variety of the press member mentioned later, for example, 10-30 mm.
The pair of inner electrode bodies 21, 21 are arranged to face each other across the tube axis C of the discharge vessel 10 with a gap G extending in the axial direction between the edges in the circumferential direction facing each other. Yes. By forming the gap G in the circumferential direction, the extension in the circumferential direction due to the thermal expansion of each inner electrode body 21, 21 can be absorbed by the gap G. Here, the size of the gap (separation distance in the circumferential direction) G is, for example, 0.1 to 1.0 mm.

  In the case where the inner electrode body 21 is configured by three or more electrode members as in the illustrated example, the lengthwise dimension of the central electrode member in the three electrode members adjacent to each other in the axial direction is It is preferable that it is smaller than the dimension of the other two electrode members in the length direction. That is, in the illustrated example, the dimension in the length direction of the second electrode member 23 is smaller than the dimension in the length direction of the first electrode member 22 and the dimension in the length direction of the third electrode member 24. Is preferred. By adopting such a configuration, it is possible to further reliably prevent the outer edge of the inner electrode body 21 from changing in the axial direction by repeatedly turning on and off the excimer lamp. The length in the length direction of the first electrode member 22 and the length in the length direction of the third electrode member 24 may be the same size or different sizes. It is preferable that the size is set.

Also, the outer diameters of the first electrode member 22, the second electrode member 23, and the third electrode member 24 are all the inner tube 12 in order to improve the adhesion with the inner peripheral surface of the inner tube 12. It is preferable that it is the magnitude | size substantially the same as the internal diameter of this. Here, the outer diameter of the electrode member refers to the size of the diameter of a circle (circumscribed circle) in contact with the outer peripheral surface of the electrode member in the longitudinal section of the electrode member.
In the above, the material of the first electrode member 22, the second electrode member 23, and the third electrode member 24 is, for example, SUS (stainless steel), aluminum, copper, or the like from the viewpoint of heat resistance and thermal conductivity. A metal material is used.

Each inner electrode body 21, 21 is provided by being pressed against the inner peripheral surface of the inner tube 12 by a pressing member disposed inside the inner tube 12.
As shown in FIG. 5, the pressing member in this example is configured by, for example, a circular plate spring (C spring) 28 formed by bending a strip-shaped metal thin plate so that the cross section has a C shape. Yes. In this example, a plurality of arc-shaped leaf springs 28 having the same shape and the same dimensions, including those that press the overlapping portion 25 of the inner electrode body 21, are provided apart from each other in the axial direction. ing.
For example, SUS (stainless steel) can be used as the material of the arc-shaped leaf spring 28.
Each arcuate leaf spring 28 preferably has an outer diameter D of the arcuate curved surface portion in a natural state (the state shown in FIG. 5) slightly larger than the inner diameter of the inner tube 12. Here, the outer diameter D of the curved surface portion refers to the diameter of a circle (circumscribed circle) in contact with the outer peripheral surface of the arcuate plate spring 28 in the axial section of the arcuate plate spring 28. With such a configuration, the inner electrode bodies 21 and 21 can be suitably adhered to the inner tube 12.

Thus, in the excimer lamp having the above-described configuration, each of the pair of inner electrode bodies 21 and 21 constituting the inner electrode 20 is divided in the axial direction and configured by three electrode members 22, 23, and 24. In addition, spot welding is performed at an overlapping portion 25 in which end portions in the length direction of adjacent electrode members are overlapped. Each inner electrode body 21 is pressed against the inner tube 12 by the pressing member 28 in the overlapping portion 25. For this reason, when the excimer lamp is turned on, each electrode member 22, 23, 24 causes the overlapping portion 25, which is a place where the pressing force is high, due to thermal expansion accompanying the increase in the temperature of the inner electrode body 21. The position where the pressing member 28 to be pressed is disposed is extended independently as a pseudo fixed point. On the other hand, when the excimer lamp is turned off, each electrode member 22, 23, 24 presses the overlapping portion 25, which is a place with a high pressing force, as the temperature of the inner electrode body 21 decreases. The position where the member 28 is disposed contracts independently as a pseudo fixed point. For this reason, the thermal expansion / contraction of the inner electrode body 21 can be reduced. In addition, the thermal expansion of the inner electrode body 21 can be mitigated by forming a gap between the edges of the first electrode member 22 and the third electrode member 24. Therefore, the sum of the extension amount and the contraction amount of each electrode member 22, 23, 24 is the same as the extension amount and the contraction amount of one continuous electrode member as in the configuration shown in FIG. Even so, the amount of displacement of the outer edge of the inner electrode body 21 can be reduced.
Further, although the displacement amount of the outer edge of the inner electrode body 21 varies depending on the arrangement position of the pressing members 28 and variations in the pressing force of the individual pressing members 28, the pressing member 28 is arranged at a position where the overlapping portion 25 is pressed. Therefore, it is possible to prevent the amount of displacement of the outer edge of the inner electrode body 21 from changing significantly. As a result, even when the excimer lamp is repeatedly turned on and off, the movement of the outer edge of the inner electrode body 21 can be suppressed.

  As described above, generally, the larger the dimension in the length direction of the inner electrode 20, the larger the displacement amount of the outer edge of the inner electrode 20. However, according to the excimer lamp of the present invention, even if the excimer lamp is repeatedly turned on and off, it is possible to prevent the position of the outer edge of the inner electrode body 21 from moving. Is particularly useful when it is configured as 900 mm or more (effective light emission length is 840 mm or more).

As mentioned above, although one embodiment of the excimer lamp of the present invention has been described, the present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the excimer lamp shown in FIG. 1, the configuration of each inner electrode body is not limited to that of the above embodiment. For example, as shown in FIG. 6, each inner electrode body 21 may be composed of two electrode members, a first electrode member 22 and a third electrode member 24. That is, in the example shown in FIG. 1, the inner electrode body does not have the second electrode member, and the end portions of the first electrode member 22 and the third electrode member 24 are spot-welded to each other. Good. Each of the inner electrode bodies may be composed of four or more electrode members that are connected to each other in the axial direction.
Moreover, the electrode member which comprises an inner side electrode body is not limited to that whose length direction cross section is a semicircle (semi-cylindrical thing).
Furthermore, the pressing member is not limited to the arcuate leaf spring (C spring) having a C-shaped cross section, and may be any member that can substantially uniformly press the inner electrode against the inner tube in the circumferential direction. .

[Example 1]
In accordance with the configuration shown in FIG. 1, an excimer lamp having the following specifications (hereinafter referred to as “lamp A1”) was manufactured.
<Lamp A1 specification>
Discharge vessel (10): material: synthetic quartz glass, total length: 1300 mm (effective light emission length: 1200 mm)
Outer tube (11): outer diameter; 40 mm
Inner tube (12): inner diameter; 14 mm
Discharge gas: Xenon gas Outer electrode (30): Material: Ni alloy, axial length: 1200 mm
Inner electrode (20): Each electrode is composed of a pair of inner electrode bodies in which three electrode members are connected in the axial direction (three to six electrode members).
Inner electrode body (21): axial length; 1200 mm
First electrode member (22): a stainless steel thin plate having a thickness of 0.2 mm formed into a semi-cylindrical shape, outer diameter: about φ14 mm, lengthwise dimension: about 600 mm
Second electrode member (23): a stainless steel thin plate having a thickness of 0.2 mm formed into a semi-cylindrical shape, outer diameter: about φ14 mm, lengthwise dimension: about 50 mm
Third electrode member (24): a stainless steel thin plate having a thickness of 0.2 mm formed into a semi-cylindrical shape, outer diameter: about φ14 mm, lengthwise dimension: about 600 mm
Overlapping part (25): lengthwise dimension: 25 mm
Separation distance (L) between the edges of the first electrode member and the third electrode member: 1 mm
Gap between edges in the circumferential direction of the inner electrode body (G): 1 mm
Pressing member (28): C spring formed by arcuate stainless steel thin plate having a thickness of 0.2 mm and a width of 10 mm, outer diameter: about φ16 mm, number: 10 pieces, arrangement position: spacing within a range of 150 mm ± 50 mm Every (the position of the overlapping part of the electrode member is 30 mm)

[Comparative Example 1]
The excimer lamp manufactured in Example 1 is a comparative excimer lamp (hereinafter referred to as “Lamp B1”) having the same specifications as the excimer lamp according to Example 1 except that the configuration of the inner electrode is changed as follows. ").
Inner electrode: composed of a pair of electrode members each formed of a semi-cylindrical stainless steel plate having a thickness of 0.2 mm Electrode member: outer diameter: about φ14 mm, lengthwise dimension: 1200 mm

[Example 2]
In the excimer lamp manufactured in Example 1, the pressing member that presses one of the overlapping portions is disposed at a position shifted to the outer side in the axial direction by 1 mm within the range of the overlapping portion. An excimer lamp (hereinafter referred to as “lamp A2”) having the same specifications as the excimer lamp according to the present invention was manufactured.

[Comparative Example 2]
In the excimer lamp manufactured in Comparative Example 1, a comparison was made except that the pressing member corresponding to the pressing member whose arrangement position was changed in the excimer lamp according to Example 2 was arranged at a position shifted to the outer side in the 1 mm axial direction. A comparative excimer lamp (hereinafter referred to as “lamp B2”) having the same specifications as the excimer lamp according to Example 1 was manufactured.

  Each of the lamps A1 and A2 according to Examples 1 and 2 and the lamps B1 and B2 according to Comparative Examples 1 and 2 is continuously turned on for 3 hours and then turned off for 1 hour as one cycle. The amount of displacement of the outer edge of the inner electrode when repeated (cycle) was examined. Here, the lamp was lit under the condition that the input per 1 cm length of the discharge space was about 10 W.

As a result, in the comparative lamp B1, the displacement amount of the outer edge of the inner electrode was 1 mm at the maximum, whereas in the lamp A1 according to the present invention, the displacement of the outer edge of the inner electrode was changed. It has been found that the amount is extremely small, and the amount of displacement of the outer edge of the inner electrode can be suppressed to be small.
Further, in the lamp A2 according to the present invention, the displacement amount of the outer edge of the inner electrode is 2.0 mm at the maximum, and the displacement amount of the outer edge of the inner electrode does not vary greatly compared to the lamp A1. There was found. That is, it has been found that the amount of displacement of the outer edge of the inner electrode does not vary greatly depending on the position of the pressing member. In contrast, in the comparative lamp B2, the maximum displacement amount of the outer edge of the inner electrode is 30 mm, and the maximum displacement amount of the outer edge of the inner electrode is larger than that of the comparative lamp B1. There was found. That is, it has been found that the amount of displacement of the outer edge of the inner electrode varies greatly depending on the position of the pressing member.

DESCRIPTION OF SYMBOLS 10 Discharge vessel 11 Outer tube 12 Inner tube 13 End wall 13a Tip tube 15 Getter chamber 16 Getter separator 18 Getter 20 Inner electrode 21 Inner electrode body (joined body)
22 1st electrode member 23 2nd electrode member 24 3rd electrode member 25 Overlapping part 28 Arc shaped leaf | plate spring (C spring)
DESCRIPTION OF SYMBOLS 30 Outer electrode 40 Discharge vessel 41 Outer tube 42 Inner tube 45 Outer electrode 46 Inner electrode 48 Pressing member 50 High frequency high voltage power source C Discharge vessel tube axis G Gap S Discharge space W Joint location

Claims (2)

A discharge vessel having a double tube structure in which an outer tube and an inner tube are coaxially disposed, an outer electrode disposed on an outer peripheral surface of the outer tube, and the discharge disposed on an inner peripheral surface of the inner tube. An excimer lamp comprising an inner electrode extending along the axial direction of the container, wherein a discharge gas is filled in a discharge space formed between the outer tube and the inner tube,
The inner electrode is composed of a plurality of electrode members, and the adjacent electrode members are spot-welded in the overlapping portion in which the end portions in the length direction of the adjacent electrode members are overlapped,
An excimer lamp, wherein a pressing member that presses the inner electrode against the inner tube is provided in the overlapping portion. The inner electrode is composed of three or more electrode members,
The lengthwise dimension of the central electrode member in the three electrode members adjacent to each other in the axial direction of the discharge vessel is smaller than the lengthwise dimension of the other two electrode members. 1. An excimer lamp according to 1.

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