JP4017277B2 - Vacuum ultraviolet laser - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum ultraviolet laser that oscillates laser light in the vacuum ultraviolet region.
[0002]
[Prior art]
Conventionally, a vacuum ultraviolet laser that oscillates a vacuum ultraviolet light having a wavelength of about 20 nm to 200 nm, which is called a vacuum ultraviolet region, is known, such as an ArF laser (193 nm) and an F2 laser (157 nm). Such a vacuum ultraviolet laser is mainly used for precision processing such as laser lithography.
[0003]
FIG. 8 shows a configuration diagram of an F2 laser as an example of a conventional vacuum ultraviolet laser.
In the figure, an F2 laser 1 encloses a laser gas, causes a discharge inside thereof, and oscillates a laser beam 11 in a vacuum ultraviolet region, and a laser beam 11 oscillated from the laser chamber 2 in a narrow band. (That is, the center wavelength of the laser light 11 is stabilized and the spectral width of the wavelength is narrowed), and the wavelength characteristics (center wavelength and spectral width) of the narrow-band laser light 11 and And a wavelength measuring device 3 for measuring power.
[0004]
Inside the laser chamber 2, for example, fluorine (F 2) and helium (He) are sealed as a laser gas at a predetermined pressure ratio, and a set of discharge electrodes 5, 5 is installed at the predetermined position. . By applying a high voltage between the discharge electrodes 5 and 5 from a high voltage power source (not shown), the laser beam 11 having a wavelength of about 157 nm is oscillated.
At this time, the upper surface opening 12 is provided on the upper end surface of the laser chamber 2, and the discharge circuit 4 connected to the discharge electrodes 5 and 5 seals the upper surface opening 12. The upper end surface of the laser chamber 2 is provided with an O-ring groove 16 over the entire periphery of the upper surface opening 12, and an O-ring 17 is inserted into the inside of the O-ring groove 16. Is sealed.
[0005]
The laser chamber 2 includes a front window 7 and a rear window 9 (hereinafter collectively referred to as windows 7 and 9) at the front end (right end in the drawing) and the rear end. The oscillated laser beam 11 is transmitted through the rear window 9 and emitted from the laser chamber 2, and enters the band narrowing unit 10 disposed behind the laser chamber 2 (left side in the drawing) to be narrowed. The The narrow-band laser beam 11 passes through the laser chamber 2, a part of which is partially transmitted through the front mirror 8 provided in front of the outside, and enters the processing machine 15.
At this time, a part of the laser beam 11 emitted from the front mirror 8 is sampled by the wavelength measuring device 3, and the wavelength characteristic and power are measured.
In general, in such an F2 laser 1, a high voltage is applied in a pulse form, and the laser beam 11 pulsates.
[0006]
At this time, the emitted laser light 11 is vacuum ultraviolet light and is very well absorbed by oxygen, water vapor, and the like in the air, so that the power is attenuated by passing through the air. In order to prevent such power attenuation, the optical path of the laser beam 11 emitted from the laser chamber 2 is sealed.
That is, as shown in the figure, the optical path of the laser beam 11 includes a wavelength box 13 covering the wavelength measuring device 3, a band narrowing box 14 covering the band narrowing unit 10, and sealing covers 22 and 22 connecting them. Are covered with optical path covers 13, 14, and 22. And the connection part of these optical path covers 13, 14, and 22 is sealed with an O-ring 25 inserted in the O-ring groove 24, and the inside of the optical path is purged with, for example, an inert gas to block air from the optical path. is doing.
[0007]
[Problems to be solved by the invention]
However, the prior art has the following problems.
[0008]
That is, a part of the laser beam 11 oscillated in the laser chamber 2 is reflected by the windows 7 and 9 and the discharge electrodes 5 and 5, and becomes irregularly reflected light 11 </ b> B, and the irregular reflection is repeated inside the laser chamber 2.
Then, as shown in FIG. 8, the irregularly reflected light 11 </ b> B enters, for example, a gap between the discharge circuit 4 and the laser chamber 2 and irradiates the O-ring 17 that seals the laser gas, so that organic matter is generated from the O-ring 17. There is a problem that this organic substance is mixed into the laser gas and contaminates the laser gas to shorten its lifetime, or adheres to the optical components in the laser chamber 2 such as the windows 7 and 9 to contaminate the optical components.
[0009]
The laser beam 11 emitted from the laser chamber 2 is reflected by an optical component (not shown) such as a mirror disposed on the optical path, for example, and a part thereof becomes irregularly reflected light 11B. Then, as shown in the figure, an O-ring 25 for entering the gap between the optical path covers 13, 14, 22 and sealing the optical path is irradiated.
As a result, the O-ring 25 is deteriorated as described above, and impurities such as air enter the optical path, and the laser light 11 is absorbed by the impurities (especially oxygen), so that the power of the laser light 11 is reduced. .
Furthermore, as described above, when organic matter is generated from the O-ring 25, there is a problem that the organic matter adheres to the optical component in the optical path and contaminates the optical component.
[0010]
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vacuum ultraviolet laser capable of preventing the O-ring from being irradiated with laser light.
[0011]
[Means, actions and effects for solving the problems]
In order to achieve the above object, a first invention provides a vacuum ultraviolet laser that oscillates laser light in a vacuum ultraviolet region, an O-ring provided in a laser chamber for sealing laser gas, or an optical path of laser light. A light shielding means for shielding at least one of the O-rings provided on the optical path cover from vacuum ultraviolet light, and the light shielding means is formed on one abutting surface of the two abutting members. And an O-ring groove, a light-shielding groove or a light-shielding recess, and a light-shielding protrusion formed on the other abutting surface at a position facing the O-ring groove, the light-shielding groove or the light-shielding recess .
According to a second aspect of the present invention, in a vacuum ultraviolet laser that oscillates laser light in a vacuum ultraviolet region, an O-ring provided in a laser chamber for sealing laser gas, or an optical path cover for sealing an optical path of the laser light. A light shielding means that shields at least one of the O-rings provided in the vacuum ultraviolet light from the vacuum ultraviolet light, and the light shielding means includes two cylindrical members inserted into the inner peripheral side of the other cylindrical member. The other cylinder at a position spaced from the end face of one cylindrical member by a predetermined distance so as to cover the gap between the contact surfaces of the two members at the front in the vacuum ultraviolet light entry direction. A light-shielding protrusion or an annular light-shielding plate is provided on the inner peripheral surface of the member.
According to a third aspect of the present invention, there is provided a vacuum ultraviolet laser that oscillates laser light in a vacuum ultraviolet region, an O-ring provided in a laser chamber for sealing laser gas, or an optical path cover for sealing an optical path of laser light. A light shielding means for shielding at least one of the O-rings provided from the vacuum ultraviolet light from the vacuum ultraviolet light, the light shielding means being provided at a contact portion between the two contact members, and between the contact surfaces of the two members An annular light shielding plate is provided on the inner surface of one of the two members so as to cover the gap in front of the entrance direction of the vacuum ultraviolet light.
[0012]
According to the first, second, and third inventions, the O-ring for sealing the laser gas has the light shielding means that prevents the vacuum ultraviolet light from being irradiated. This light shielding means is opposed to the O-ring groove, light shielding groove or light shielding recess formed on one abutting surface of the two abutting members, and opposed to the O ring groove, light shielding groove or light shielding recess on the other abutting surface. The light-shielding protrusion formed at the position to be fitted is fitted. Thereby, since vacuum ultraviolet light is not irradiated to the O-ring of the laser chamber, organic substances are hardly generated from the O-ring. Accordingly, it is unlikely that the organic substance is mixed into the laser gas and the power and wavelength characteristics of the laser light are reduced, or the organic substance is attached to the optical element in the laser chamber and the optical element is soiled. Therefore, it is possible to operate the vacuum ultraviolet laser stably over a long period of time.
[0013]
Further, the O-ring for sealing the optical path is provided with a light shielding means for preventing the vacuum ultraviolet light from being irradiated. This light-shielding means is a position in which one cylindrical member is spaced a predetermined distance from the end surface of one cylindrical member in the gap between the contact surfaces of the two members that are inserted into the inner peripheral side of the other cylindrical member. The other of the cylindrical members is covered with a light shielding protrusion or an annular light shielding plate in front of the entrance direction of the vacuum ultraviolet light. In addition, the gap between the contact surfaces of the two contact members is provided in the contact portion of the two contact members, and an annular light shielding plate provided on the inner surface of either member is used in front of the entrance direction of the vacuum ultraviolet light. Covered with. Thereby, since vacuum ultraviolet light is not irradiated to the O-ring, the O-ring is rarely deteriorated. Accordingly, since the optical path is well sealed and shielded from the air, the laser beam is less absorbed and the power is less attenuated. In addition, the O-ring has a longer life and the maintenance interval of the vacuum ultraviolet laser becomes longer. Further, since vacuum ultraviolet light is not irradiated to the O-ring, organic substances are rarely generated from the O-ring. As a result, the optical path is well sealed, so that organic substances are mixed in the optical path and adhere to the optical element in the optical path so that the laser beam is not absorbed and the optical element is hardly damaged. Therefore, it is possible to operate the vacuum ultraviolet laser stably over a long period of time.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In the embodiment, the same elements as those used in the description of the prior art are denoted by the same reference numerals, and redundant description is omitted.
[0015]
An embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an F2 laser will be described as an example of a vacuum ultraviolet laser.
FIG. 1 is a configuration diagram of an F2 laser according to the present embodiment. In this figure, an F2 laser 1 encloses a laser gas, encloses a laser gas, generates a discharge therein, and oscillates a laser beam 11 in a vacuum ultraviolet region, and a laser beam 11 oscillated from the laser chamber 2 in a narrow band. And a wavelength measuring unit 3 that measures the wavelength characteristics and power of the laser beam 11 that has been narrowed.
[0016]
The laser chamber 2 includes substantially cylindrical window holders 6 and 6 at the front end portion and the rear end portion thereof, respectively, and a front window 7 and a rear window 9 are fixed to the front ends thereof at predetermined angles, respectively.
The laser chamber 2 is filled with, for example, fluorine (F2) and helium (He) as a laser gas at a predetermined pressure ratio, and a set of discharge electrodes 5 and 5 are provided at predetermined positions inside the laser chamber 2. is set up.
A cross-flow fan 26 is installed at a predetermined position of the laser chamber 2 and is driven to rotate by a motor (not shown) to send laser gas between the discharge electrodes 5 and 5. Then, by applying a high voltage between the discharge electrodes 5 and 5 from a high voltage power source (not shown), the laser gas is excited by discharge to oscillate the laser beam 11 having a wavelength of about 157 nm.
In general, in such an F2 laser 1, a high voltage is applied in a pulse form, and the laser beam 11 pulsates.
[0017]
The laser beam 11 oscillated in the laser chamber 2 passes through the rear window 9 and enters the band narrowing unit 10 provided on the rear rear side of the laser chamber 2.
The band narrowing unit 10 includes, for example, two prisms 32 and 32 and a grating 33 which is a wavelength selection element. Then, the laser beam 11 expanded by the prisms 32 and 32 is incident on the grating 33, and only the laser beam 11 having a predetermined wavelength characteristic is folded back in the same direction as the incident beam, so that the laser beam 11 is narrowed.
The narrow-band laser beam 11 is emitted from the narrow-band unit 10, passes through the laser chamber 2, and passes through the front window 7 provided at the front end of the laser chamber 2. A part of the laser beam 11 transmitted through the front window 7 is partially reflected by the front mirror 8 provided in front of the laser chamber 2 and returned to the laser chamber 2. The remaining laser light 11 is partially transmitted through the front mirror 8 and enters the wavelength measuring device 3.
At this time, a part of the laser beam 11 is reflected by the windows 7 and 9 and the discharge electrodes 5 and 5, and becomes irregularly reflected light 11 </ b> B and is repeatedly irregularly reflected inside the laser chamber 2.
[0018]
The wavelength measuring device 3 has a beam splitter 12 on the optical path of the incident laser beam 11. The laser beam 11 is partly reflected downward in the figure by the beam splitter 12 and becomes sample light 11A. Further, the laser beam 11 transmitted through the beam splitter 12 is incident on the processing machine 15 and serves as a light source for performing precision processing therein.
A part of the sample light 11A reflected downward by the beam splitter 12 is reflected by the second beam splitter 34, and enters a power detector 35 including, for example, a photodiode, and its power is measured. The sample light 11A that has passed through the second beam splitter 34 is incident on a wavelength detector 36 having a spectroscopic means such as an etalon, and its wavelength characteristics are detected.
[0019]
At this time, since the laser light 11 which is vacuum ultraviolet light is absorbed very well by oxygen, water vapor, etc. in the air, the power is attenuated by passing through the air.
In order to prevent such power attenuation, the narrow band unit 10 and the wavelength measuring device 3 are housed in the narrow band box 14 and the wavelength box 13, respectively. Further, the space between the laser chamber 2 and the wavelength box 13 and the narrow band box 14 is covered with sealing covers 22 and 22, respectively. The optical path covers 13, 14, and 22 that cover these optical paths form a sealed structure by the O-ring groove 24 and an O-ring 25 that is inserted into the O-ring groove 24, and purge the interior of the optical path with, for example, an inert gas. Air is shut off.
[0020]
Note that when the laser beam 11 is oscillated, the laser chamber 2 expands in the optical axis direction (left and right direction in the drawing) of the laser beam 11 by heat generated from the discharge between the discharge electrodes 5 and 5. At this time, if the narrowing box 14 and the wavelength box 13 and the window holder 6 are fixed, the expansion causes the narrowing unit 10 and the wavelength measuring device 3 to be pushed in the optical axis direction, and the F2 laser 1 The optical axis will be shifted. In order to avoid this, the window holders 6 and 6 are slidable in the optical axis direction while keeping the optical path sealed with respect to the sealing covers 22 and 22 fixed to the narrow band box 14 and the wavelength box 13, respectively. Yes.
[0021]
Hereinafter, a light shielding unit for preventing the O-ring 17 provided in the laser chamber 2 for sealing the laser gas from being irradiated to the irregularly reflected light 11B will be described.
[0022]
As shown in FIG. 1, the laser chamber 2 includes an upper chamber 2A and a lower chamber 2B, a flange portion formed on the lower end surface of the upper chamber 2A, and a flange portion formed on the upper end surface of the lower chamber 2B. The two flange portions are fixed to each other with bolts or the like (not shown).
FIG. 2 is a detailed cross-sectional view of a P portion in FIG. As shown in the figure, an O-ring groove 16 is provided over the entire periphery of the flange portion contact surface of the upper end surface of the lower chamber 2B, and an O-ring 17 fitted into the O-ring groove 16 and the upper portion The laser gas is sealed between the lower end face of the chamber 2A and the flange contact surface.
At this time, a light-shielding groove 28 is provided on the entire upper end surface of the lower chamber 2B on the inner peripheral side with respect to the O-ring groove 16. In addition, the flange portion on the lower end surface of the upper chamber 2 </ b> A facing the light shielding groove 28 has a light shielding width slightly narrower than the light shielding groove 28 and slightly lower than the depth of the light shielding groove 28. The protrusion 27 is provided over the entire circumference.
As shown in the figure, when the upper chamber 2A is fixed to the lower chamber 2B, the light shielding protrusion 27 is fitted into the light shielding groove 28. That is, since the light shielding groove 28 and the light shielding protrusion 27 constitute a labyrinth, the irregularly reflected light 11B inside the laser chamber 2 is shielded by the labyrinth, and the O-ring 17 is shielded from the irregularly reflected light 11B.
[0023]
3 and 4 show other examples of light shielding means for shielding the O-ring 17 at the same location as that in FIG.
In FIG. 3, a light shielding plate 29 is detachably fixed to an inner wall of the upper chamber 2A by a fixing means such as a bolt 30. The light shielding plate 29 prevents the irregularly reflected light 11B from entering the gap between the flange portion on the lower end surface of the upper chamber 2A and the flange portion on the upper end surface of the lower chamber 2B, and shields the O-ring 17 from the irregularly reflected light 11B. Yes.
In FIG. 4, the flange portion on the lower end surface of the upper chamber 2A is provided with a light-shielding protrusion 27 on the entire inner periphery side of the O-ring groove 16, and the flange portion on the upper end surface of the lower chamber 2B. It faces the light shielding recess 31 provided over the entire circumference. The light shielding protrusion 27 and the light shielding recess 31 prevent the irregularly reflected light 11B from entering the gap between the upper chamber 2A and the lower chamber 2B, and shields the O-ring 17 from the irregularly reflected light 11B.
The shapes of the light-shielding protrusion 27 and the light-shielding recess 31 are not limited to this. For example, as shown by a two-dot chain line in FIG. 31 may be formed obliquely.
[0024]
Further, in FIG. 1, an upper surface opening 12 is provided in the flange portion of the upper end surface of the upper chamber 2A, and the discharge circuit 4 connected to the discharge electrodes 5 and 5 is fixed so as to close the upper surface opening 12. The laser gas is sealed. An O-ring 17 is also used at this sealing location, and a light shielding means for shielding the O-ring 17 will be described below.
FIG. 5 is a detailed cross-sectional view of the Q portion in FIG. In the same figure, an O-ring groove 16 is provided on the upper end surface of the upper chamber 2A around the entire periphery of the upper surface opening 12, and an O-ring 17 is fitted therein. A light shielding protrusion 27 is formed on the lower end surface of the discharge circuit 4 at a position facing the O ring groove 16 and abutting against the O ring 17 over the entire circumference, and between the light shielding protrusion 27 and the O ring 17. The laser gas is sealed.
The light shielding protrusion 27 shields the irregularly reflected light 11B entering the gap between the discharge circuit 4 and the upper chamber 2A, and shields the O-ring 17 from the irregularly reflected light 11B.
[0025]
As described above, since the O-ring 17 provided in the laser chamber 2 has the light shielding means that does not irradiate the irregularly reflected light 11B, deterioration of the O-ring 17 is prevented. In addition, since the irregularly reflected light 11B does not strike the O-ring 17, contamination of the laser gas due to the generation of organic substances from the O-ring 17 is prevented.
[0026]
As the O-ring 17 that seals the laser gas, an O-ring 17 that seals between the discharge circuit 4 and the laser chamber 2 and an O-ring 17 that seals between the upper chamber 2A and the lower chamber 2B are illustrated. However, the object which the light shielding means shields is not limited to these. For example, for all O-rings 17 that seal laser gas, such as O-rings that seal introduction means (not shown) for driving a cross-flow fan 26 and that introduces a driving force of a motor (not shown). Applicable.
The O-ring groove 16 may be provided on any side of the discharge circuit 4, the upper chamber 2A, and the lower chamber 2B.
[0027]
Next, an example of a light shielding unit that shields the O-ring 25 for sealing the optical path of the laser light 11 emitted from the laser chamber 2 from the irregularly reflected light 11B in the optical path will be described.
[0028]
FIG. 6 is a detailed cross-sectional view of the R portion in FIG. 1, and shows a configuration example of a connection portion between the window holder 6 fixed to the laser chamber 2 and the sealing cover 22 fixed to the band narrowing box 14. ing.
In the figure, an O-ring groove 24 is provided on the outer peripheral surface of the substantially cylindrical window holder 6, and an O-ring 25 is fitted inside the O-ring groove 24. The window holder 6 is inserted into the inner peripheral side of the substantially cylindrical sealing cover 22 and seals the optical path between the inner peripheral surface of the sealing cover 22 and the O-ring 25. Further, a light shielding protrusion 27 is provided on the inner peripheral surface of the sealing cover 22 outside the end surface of the window holder 6 over the entire periphery. The light shielding protrusion 27 prevents the irregularly reflected light 11B from entering the gap between the sealing cover 22 and the window holder 6, and shields the O-ring 25 from the irregularly reflected light 11B.
Alternatively, at this time, instead of providing the light shielding protrusion 27 on the inner peripheral surface of the sealing cover 22, an L-shaped cross section is formed at substantially the same position (in the drawing, the light shielding plate 29 is drawn shifted). The annular light shielding plate 29 may be fixed with a bolt 30 or the like. As described above, the laser chamber 2 expands in the direction of the arrow in the drawing when the laser beam 11 oscillates. In this case, a predetermined gap is provided so that the window holder 6 does not collide with the light shielding protrusion 27 and the light shielding plate 29. It is necessary to provide and configure L.
[0029]
FIG. 7 is a detailed cross-sectional view of the S portion in FIG. 1 and shows a configuration example of a connection portion between the band narrowing box 14 and the sealing cover 22.
In the figure, a flange 22 </ b> A is formed at one end of the sealing cover 22, and the flange 22 </ b> A is fixed to the side surface of the band narrowing box 14 with a bolt (not shown). An O-ring groove 24 is formed on the entire end surface of the flange 22A, and an O-ring 25 is fitted therein. The O-ring 25 and the side surface of the band narrowing box 14 are in contact with each other to seal the optical path.
A substantially cylindrical light shielding plate 29 is fixed to the inner peripheral surface of the sealing cover 22 by a bolt 30 or the like over the entire circumference to shield the O-ring 25 from the irregularly reflected light 11B. At this time, if an annular light shielding protrusion 27 is formed on the outer peripheral portion on one end side of the light shielding plate 29 as indicated by a two-dot chain line in the drawing, the light shielding performance is further improved.
[0030]
As described above, the O-ring 25 on the narrow band box 14 side has been described as an example, but these light shielding means are provided on the O-ring 25 (see FIG. 1) provided in the optical path on the wavelength box 13 side from which the laser light 11 is emitted. The same applies to the case.
[0031]
In this embodiment, an O-ring 25 provided at the connection between the sealing cover 22 and the narrow-band box 14, the wavelength box 13, and the window holders 6 and 6 is used as the O-ring 25 that seals the optical path. Although illustrated, it is not restricted to these. For example, the narrow-band box 14 and the wavelength box 13 also use O-rings (not shown) for sealing them, and the irregularly reflected light 11B is generated from the laser light 11 and the sample light 11A therein. . These O-rings and the like are also provided with a light shielding means for shielding light from the irregularly reflected light 11B.
[0032]
As described above, according to the present embodiment, in the vacuum ultraviolet laser such as the F2 laser 1, the light shielding means for shielding the O-ring 17 for sealing the laser gas from the vacuum ultraviolet light (the light shielding protrusion 27, according to the embodiment). It has a light shielding groove 28, a light shielding plate 29, and a light shielding recess 31). In the embodiment, only the irregularly reflected light 11B is exemplified as the vacuum ultraviolet light. However, the O-rings 17 and 25 may be irradiated with the laser light 11 and the sample light 11A when adjusting the optical axis, for example. It is also effective as a light shielding means for shielding such laser light 11 and sample light 11A.
Thereby, since vacuum ultraviolet light is not irradiated to the O-ring 17, organic substances are hardly generated from the O-ring 17. As a result, organic substances are mixed into the laser gas, and the power and wavelength characteristics of the laser beam 11 are reduced, and the organic substances are less likely to adhere to the optical elements in the laser chamber 2 and the optical elements are soiled. Therefore, it is possible to operate the vacuum ultraviolet laser stably over a long period of time.
[0033]
Further, in the vacuum ultraviolet laser, in order to seal the optical path through which the laser beam 11 passes, the O-ring 25 provided in the optical path covers 14, 13, 22 is shielded from the vacuum ultraviolet light (according to the embodiment). It has a light shielding protrusion 27 and a light shielding plate 29).
Thereby, since the vacuum ultraviolet light is not irradiated to the O-ring 25, the O-ring 25 is less deteriorated and the optical path is well sealed. Therefore, air hardly enters the optical path, and the laser light 11 is not absorbed, so that the power attenuation is small. Further, the life of the O-ring 25 is extended, and the maintenance interval of the vacuum ultraviolet laser is increased. Further, since vacuum ultraviolet light is not irradiated onto the O-ring 25, organic substances are rarely generated from the O-ring 25. Thereby, organic substances are mixed in the optical path and adhere to the optical element, and the optical element is less likely to be contaminated. Therefore, it is possible to operate the vacuum ultraviolet laser stably over a long period of time.
[0034]
In this embodiment, the light shielding means as shown in FIGS. 2 to 7 is exemplified as the light shielding means for shielding the O-rings 17 and 25, but the light shielding means is not limited to the exemplified means. That is, other light shielding means may be used as long as the light shielding means shields the O-rings 17 and 25 from the vacuum ultraviolet light in the optical path or the laser chamber 2.
Further, the combination of the light shielding means and the O-rings 17 and 25 to be shielded from light is not limited to the illustrated combination. That is, when designing a vacuum ultraviolet laser, light shielding means may be provided as appropriate according to the shape of the laser chamber 2, the optical path covers 13, 14, 22 and the like.
[0035]
Further, although the F2 laser narrowed by the grating 33 has been described as an example of the vacuum ultraviolet laser, the wavelength selection element for narrowing the band is not limited to the grating 33 but may be an etalon or a dispersion prism, for example. Furthermore, the laser is not limited to a narrow band laser, and a rear mirror or the like may be disposed instead of the narrow band unit 10.
The present invention is not limited to the F2 laser, but can be applied to all gas lasers that oscillate vacuum ultraviolet light, such as the ArF excimer laser described above. Further, the present invention can be applied not only to a gas laser excited by discharge but also to a gas laser excited by means other than discharge (for example, a laser beam).
Furthermore, the present invention can be applied to vacuum ultraviolet lasers other than gas lasers. That is, in the vacuum ultraviolet laser other than the gas laser, the O-ring 17 for sealing the laser gas is not necessary, but generally an O-ring 25 is provided to seal the optical path. Is possible. By providing such a light shielding means, it is possible to prevent the deterioration of the O-ring 25 and the generation of organic substances due to the irradiation of vacuum ultraviolet light.
[0036]
In the embodiment, the inert gas is sealed in the sealed optical path. However, the present invention is not limited to this. For example, a means for purging the inert gas in the optical path, and evacuating the optical path. And an inert gas may be continuously purged into the optical path. Alternatively, the optical path may be evacuated to remove oxygen in the optical path. In such a case, the shape of the O-ring groove 24 and the diameter of the O-ring 25 are appropriately selected according to the pressure in the optical path.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an F2 laser according to an embodiment of the present invention.
2 is a detailed cross-sectional view of a portion P in FIG. 1. FIG. 3 is a cross-sectional view showing another example of the light shielding means.
FIG. 4 is a cross-sectional view showing another example of the light shielding means.
5 is a detailed cross-sectional view of a portion Q in FIG.
6 is a detailed cross-sectional view of a portion R in FIG.
7 is a detailed cross-sectional view of a portion S in FIG.
FIG. 8 is a cross-sectional view of a conventional F2 laser.
[Explanation of symbols]
1: F2 laser, 2: laser chamber, 2A: upper chamber, 2B: lower chamber, 3: wavelength measuring device, 4: discharge circuit, 5: discharge electrode, 6: window holder, 7: front window, 8: front mirror , 9: Rear window, 10: Narrow band unit, 11: Laser light, 11A: Sample light, 11B: Diffuse reflected light, 12: Beam splitter, 13: Wavelength box, 14: Narrow band box, 15: Processing machine, 16: O-ring groove, 17: O-ring, 22: sealing cover, 24: O-ring groove, 25: O-ring, 26: cross-flow fan, 27: light-shielding protrusion, 28: light-shielding groove, 29: light-shielding plate, 30: bolt , 31: light shielding recess, 32: prism, 33: grating, 34: beam splitter, 35: power detector, 36: wavelength detector.

Claims (3)

In the vacuum ultraviolet laser (1) that oscillates the laser light (11) in the vacuum ultraviolet region,
O-ring (17) provided in the laser chamber (2) for sealing the laser gas, or O-ring provided in the optical path cover (13, 14, 22) for sealing the optical path of the laser beam (11) (25) provided with light shielding means ( 27, 28, 31 ) for shielding light from vacuum ultraviolet light (11, 11A, 11B) ,
The light shielding means includes an O ring groove (16) , a light shielding groove (28) or a light shielding recess (31) formed on one abutting surface of two abutting members, and the O ring on the other abutting surface. A vacuum ultraviolet laser (1) having a groove (16) , a light shielding protrusion (27) formed at a position facing the light shielding groove (28) or the light shielding recess (31 ). Laser light in the vacuum ultraviolet region (11) Vacuum ultraviolet laser that oscillates (1) In
Laser chamber to seal laser gas (2) O-ring provided on (17) Or laser light (11) Light path cover to seal the light path of (13,14,22) O-ring provided on (twenty five) At least one of the vacuum ultraviolet light (11,11A, 11B) Light shielding means to shield from light (27,29)
With
The light blocking means is one cylindrical member (6) Is the other cylindrical member (twenty two) Both members are provided in the fitting insertion part of the two members that are fitted on the inner peripheral side of the (6,22) One cylindrical member so as to cover the gap between the contact surfaces of the two in front of the entrance direction of the vacuum ultraviolet light (6)
The other cylindrical member at a position separated from the end face by a predetermined distance (twenty two) Shading protrusion on the inner peripheral surface of (27) Or an annular shading plate (29) Provided
A vacuum ultraviolet laser characterized by that. Laser light in the vacuum ultraviolet region (11) Vacuum ultraviolet laser that oscillates (1) In
Laser chamber to seal laser gas (2) O-ring provided on (17) Or laser light (11) Light path cover to seal the light path of (13,14,22) O-ring provided on (twenty five) At least one of the vacuum ultraviolet light (11,11A, 11B) Light shielding means to shield from light (29) With
The light shielding means is two abutting members (14,22) Both members (14,22)
The both members so as to cover the gap between the contact surfaces of the two in front of the entrance direction of the vacuum ultraviolet light (14,22) An annular shading plate on the inner surface of either (29) Provided
A vacuum ultraviolet laser characterized by that.

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