JP6483020B2 - Discharge lamp, discharge lamp manufacturing method, and discharge lamp electrode - Google Patents

Description

  The present invention relates to a discharge lamp used in an exposure apparatus or the like, and more particularly, to an electrode structure in which a plurality of metal members are joined.

  In a short arc type discharge lamp, an object to be exposed such as a substrate is irradiated with high-intensity light. In order to increase the size of the object to be exposed and further improve the throughput, it is required to increase the output of the discharge lamp, and accordingly, the rated power consumption must be increased.

  When the power is increased, the conventional single metal electrode structure affects the electron emission, heat emission, durability, and the like. In addition, since the weight of the electrode increases, the load on the electrode support rod and the like is large.

  Therefore, it has been proposed to form an electrode by joining a plurality of metals. For example, an electrode is formed by solid-phase joining a tip portion of an electrode made of tritium tungsten containing thorium or the like and a rear body portion made of pure tungsten or the like (see Patent Documents 1 and 2).

JP 2011-154927 A JP 2011-070823 A

  When an electrode is configured by solid-phase bonding of different metals, a gap is likely to be generated near the outer edge of the bonded surface as the temperature increases or decreases during bonding due to a difference in thermal expansion coefficient. If the electrode becomes hot when the lamp is lit, the gap may be enlarged and the electrode may be damaged. In addition, a wedge-shaped gap is formed in the vicinity of the bonding surface even in an electrode in which the same metal member is solid-phase bonded.

  Therefore, in the electrode formed by solid phase bonding, it is necessary to increase the bonding strength in the vicinity of the bonding surface.

  The discharge lamp of the present invention includes a discharge tube and a pair of electrodes disposed in the discharge tube, and at least one of the electrodes is constituted by an electrode obtained by solid-phase bonding a front end side member and a rear end side member. The The front end side member is in a position close to the electrode front end surface side, that is, the other electrode side, and the rear end side member is in a position close to the electrode support bar. The rear end side member is higher / larger than the front end side member.

  The front end side member and the rear end side member can be configured by a metal member. For example, the front end side member can be constituted by triated tungsten, and the rear end side member can be constituted by molybdenum having relatively high extensibility.

  In the present invention, the groove portion is formed on the side surface of the electrode so as to straddle the joint surface between the front end side member and the rear end side member, that is, the joint surface is interposed therebetween. However, the “electrode side surface” includes both the tapered surface formed on the electrode tip side and the side surface (outer peripheral surface) of the body portion.

  The groove formed for improving the bonding strength has a groove pitch and a groove depth that are smaller than the pitch and depth of the heat radiating groove on the order of millimeters. For example, it is possible to form grooves having a pitch and depth of 100 μm or less. By forming such a fine groove, the vicinity of the outer edge of the joining surface of the rear end side member having high spreadability is deformed relatively deeply.

  The groove portion including such a joining surface may have a surface roughness Ra of the rear end side surface of 1.2 μm or more. Further, the surface roughness Ra of the side surface of the tip side member may be 0.7 μm or less. Furthermore, what is necessary is just to form a groove part so that the reflectance of a rear end side member side surface may become smaller than the reflectance of a front end side member side surface. By satisfying such numerical values, the joint surface strength can be improved.

  About a fine groove | channel, a wedge vicinity can be deformed by forming a coarse groove | channel compared with a front end side member. For example, the groove may be formed on the side surface of the rear end side member so that “goe or burr” occurs. That is, the groove is preferably formed so as to be partially torn off or peeled off. On the other hand, in consideration of arc discharge stability, it is preferable to form a fine groove with no peeling on the side surface of the tip side member of the groove.

  It is also possible to configure the fine groove so that it is deeper on the rear end side surface than on the front end side surface. In the vicinity of the wedge, the rear end side metal member surface is easily deformed.

  When the electrode is formed by cutting, the groove is preferably formed in the cutting after the solid phase bonding of the electrode. By simultaneously forming the groove during cutting using a lathe, the manufacturing process is not complicated.

  In the groove portion, it is possible to form a wide groove having a larger pitch and depth than the fine groove across the joint surface.

  According to another aspect of the present invention, there is provided a method for manufacturing a discharge lamp, in which a front end side member and a rear end side member having higher extensibility than the front end side member are solid-phase bonded, and a side surface of the electrode member subjected to solid phase bonding is cut. In the manufacturing method of the discharge lamp to be processed, in the cutting process, the groove is formed on the side surface of the electrode member so as to straddle the joint surface between the front end side member and the rear end side member. For example, in the cutting process, fine grooves due to peeling may be formed on the side surface of the rear end side member.

  An electrode for a discharge lamp according to another aspect of the present invention includes a front end side member and a rear end side member solid-phase bonded to the front end side member, and the groove portion serves as a bonding surface between the front end side member and the rear end side member. It is formed on the electrode side face across. It is also possible to perform solid-phase bonding of the members having the same spreadability.

  ADVANTAGE OF THE INVENTION According to this invention, the electrode which raised joint strength can be comprised in the electrode which carried out the solid phase joining of the several member.

It is the top view which showed typically the short arc type discharge lamp which is 1st Embodiment. It is a schematic side view of an anode and a cathode. It is a partial side view of a cathode. It is the figure which expanded the metal member joining surface vicinity in a cathode. It is a partial side view of the cathode in 2nd Embodiment. It is a figure showing the photograph of the cathode of joining surface vicinity. It is the figure showing the enlarged photograph of FIG. It is a figure showing the photograph of the joint surface vicinity by an electron microscope.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view schematically showing the short arc type discharge lamp according to the first embodiment.

  The short arc type discharge lamp 10 is a discharge lamp that can be used as a light source of an exposure apparatus (not shown) for pattern formation, and includes a transparent quartz glass discharge tube (light emitting tube) 12. A cathode 20 and an anode 30 are opposed to the discharge tube 12 with a predetermined interval.

  On both sides of the discharge tube 12, quartz glass sealing tubes 13A and 13B are provided integrally with the discharge tube 12 so as to face each other, and both ends of the sealing tubes 13A and 13B are formed by caps 19A and 19B. It is blocked. Here, the discharge lamp 10 is arranged along the vertical direction so that the anode 30 is on the upper side and the cathode 20 is on the lower side.

  Inside the sealing tubes 13A and 13B, conductive electrode support rods 17A and 17B for supporting the metallic cathode 20 and the anode 30 are disposed, a metal ring (not shown), and a metal foil 16A such as molybdenum. , 16B to the conductive lead rods 15A, 15B, respectively. The sealing tubes 13A and 13B are welded to glass tubes (not shown) provided in the sealing tubes 13A and 13B, thereby sealing the discharge space DS in which mercury and a rare gas are sealed. The

  The lead rods 15A and 15B are connected to an external power source (not shown), and are connected between the cathode 20 and the anode 30 via the lead rods 15A and 15B, the metal foils 16A and 16B, and the electrode support rods 17A and 17B. A voltage is applied to. When electric power is supplied to the discharge lamp 10, arc discharge occurs between the electrodes, and a bright line (ultraviolet light) due to mercury is emitted.

  FIG. 2 is a schematic side view of an anode and a cathode.

  The cathode 20 includes a metal member (front end side member) 20A having an electrode front end surface 20S perpendicular to the electrode axis E, and a metal member (rear end side member) 20B joined to the metal member 20A behind the metal member 20A. The metal member 20B supported by the electrode support rod 17A includes a columnar portion 23B and a truncated cone-shaped portion 23A, and the truncated cone-shaped metal member 20A is joined to the truncated cone-shaped portion 23A of the metal member 20B.

  The anode 30 includes a metal member (front end side member) 30A having an electrode front end surface 30S perpendicular to the electrode axis E, and a metal member (rear end side member) 30B joined to the metal member 30A. The metal member 30A includes a truncated cone portion 33A and a columnar portion 33B, and the columnar metal member 30B is joined to the columnar portion 33B of the metal member 30A.

  The tip-side metal member 20A is made of an alloy mainly composed of tungsten such as triated tungsten or a high melting point metal such as pure tungsten (W). On the other hand, the metal member 20B on the rear end side is made of a metal having higher extensibility than the metal member 20A or an alloy containing the metal as a main component. Here, the metal member 20B is made of molybdenum (Mo). The metal members 30A and 30B of the anode 30 are made of pure tungsten (W) and molybdenum (Mo), respectively.

  FIG. 3 is a partial side view of the cathode. FIG. 4 is an enlarged view of the vicinity of the metal member bonding surface in the cathode. The groove formed on the side surface of the cathode will be described with reference to FIGS.

  The cathode 20 is manufactured by solid-phase joining the materials to be the metal members 20A and 20B obtained by sintering and solidifying a metal powder according to a discharge plasma sintering (SPS sintering) method, and then cutting with a lathe. Is done. The tapered surface (reduced diameter surface) 20Q of the cathode 20 is formed by the cutting process.

  In the cutting process, the metal members 20A and 20B are cut along a direction perpendicular to the electrode axis E, that is, along the circumferential direction. Here, cutting is performed at an angle α of ± 10 ° or less with respect to the bonding surface S1. Then, in the cutting process for forming the electrode having the tapered surface 20Q, the groove R is simultaneously formed.

  The groove R is formed across the joining surface S1, and is formed of a fine groove (hereinafter referred to as a fine groove). The fine grooves r are grooves formed at a predetermined pitch interval P1 simultaneously with the cutting process, and the pitch interval P1 is set in a range of 1 μm to 5 μm. This is sufficiently smaller than the heat radiation groove formed in the conventional discharge lamp. In FIG. 4, regarding the fine groove r, the fine groove formed in the metal member 20A is represented as “r1A”, and the fine groove formed in the metal member 20B is represented as “r1B”.

  The fine groove r1B formed in the metal member 20B on the rear end side is a peeled groove, and the groove depth d reaches a position deeper than the tool cutting edge ridge position. However, the groove depth d is shown here as the distance from the line connecting the groove peak points to the bottom. On the other hand, a fine groove r1A that does not peel or hardly occurs is formed in the metal member 20A having relatively low spreadability. The groove depth d is smaller (shallow) on the metal member 20A side than on the metal member 20B side.

  The number of rotations / rotation speed of the lathe at the time of cutting, the material of the blade, the cutting angle, the cutting amount, etc., so as to form fine grooves r having different surface conditions such as depth and roughness across the joining surface S1. Is adjusted. Here, the adjustment is performed so that a difference in groove occurs at the joint surface S1 during continuous cutting.

  The groove depth d in the metal member 20B is relatively uneven because it is a groove due to peeling, but the cutting depth of the blade is adjusted so that the depth is 5 μm or more. On the other hand, the cut amount and the like are adjusted so as to prevent the metal member 20A from being peeled.

  When the metal surface becomes rough, irregular reflection of light increases and the reflectance decreases. Originally, the reflectance of light is larger in molybdenum than in tungsten. However, by forming the fine grooves r (r1A, r1B), the reflectance on the metal member 20B side in the groove portion R is the same as that on the metal member 20A side. It becomes smaller than the reflectance. Moreover, the surface roughness Ra of the metal member 20B is 1.2 μm or more and the surface roughness Ra of the metal member 20A is 0.7 μm or less by cutting.

  As described above, the metal member 20B made of molybdenum (Mo) on the rear end side has higher spreadability than the metal member 20A made of tungsten (W) on the front end side, and is easily deformed. Therefore, when the metal members 20A and 20B are solid-phase bonded, a wedge W tends to be generated near the outer edge of the bonding surface S1, as shown in FIG. The wedge W often occurs at the micro order level.

  However, when the fine groove r is formed in the vicinity of the joint surface S1, in the metal member 20B having relatively high extensibility, the fine groove r1B is formed so as to cause peeling, so that the vicinity of the outer edge of the joint surface S1. In this case, plastic deformation occurs. This is brought about by adjusting the force applied to the metal member 20B at the time of cutting and performing the cutting along the joining surface S1 (within 10 °). As a guideline for forming such a fine groove r1A, cutting may be performed so that the above-described surface roughness Ra is 1.2 μm or more.

  As a result, the shape of the wedge W also changes and becomes the same size as the fine groove r formed near the joint surface S1. The wedge W generated on the joint surface S1 changes in shape from a state of being deeply cut to the electrode center side, and in some cases, the wedge W is in a crushed state. This prevents the joint from being damaged starting from the wedge due to the difference in thermal expansion in the vicinity of the joint surface S1 during lamp operation.

  In particular, the taper surface 20Q has a high current density, and thermal stress due to the difference in thermal expansion coefficient acts greatly from the metal member 20B toward the metal member 20A. However, since the bonding strength is high, high thermal conductivity and electrical conductivity are achieved. Can be maintained. Thereby, the thorium content in the tip side metal member 20A can be kept to the minimum necessary.

  Further, by forming the minute groove r1A in the metal member 20A on the front end side, when a thermal stress is applied from the metal member 20B to the metal member 20A during lamp lighting, the thermal stress is released by the minute groove r1A. It is possible to prevent chipping in the vicinity of the joint surface S1. In order to realize this, the fine groove r1A may be formed so that the surface roughness Ra is 0.7 μm or less.

  Further, by the plastic deformation by cutting near the surface of the metal member 20B, a fine groove r1B that bites into the electrode center side is formed in the vicinity of the joint surface S1 of the metal member 20B, and the joint near the outer edge of the joint surface S1. Can be strengthened. In particular, when the metal member 20B is formed of pure molybdenum, peeling easily occurs and the surface roughness Ra is easily increased.

  On the other hand, in the fine groove r1A on the side surface of the metal member 20A, since no peeling is substantially generated, the pitch and depth are grooves with no disturbance. As a result, no crack or chipping occurs in the metal member 20A made of tungsten having low extensibility, and arc discharge during lamp operation is stabilized. Since such fine grooves r are formed simultaneously with the cutting process, the electrode manufacturing process is not complicated.

  Although the groove portion R formed on the tapered surface 20Q of the cathode 20 has been described above, the same groove portion as that of the cathode 20 is formed also in the anode 30. As a result, a groove is formed in the metal member 30A made of tungsten and the metal member 30B made of molybdenum with the joining surface S2 interposed therebetween, and a fine groove with a peeling is formed in the metal member 30B. Thereby, joint strength, thermal conductivity, and electrical conductivity can be improved.

  Thus, according to the present embodiment, the cathode 20 composed of the metal member 20A on the front end side and the metal member 20B on the rear end side is formed by solid phase bonding and cutting. A groove portion R in which fine grooves r are formed is formed on the tapered surface 20Q of the cathode 20 formed at the time of cutting. At this time, cutting is performed so that peeling occurs in the metal member 20B but does not occur in the metal member 20A.

  Next, the short arc type discharge lamp which is 2nd Embodiment is demonstrated using FIG. In the second embodiment, a heat radiating groove is further formed.

  FIG. 5 is a side view of the cathode in the second embodiment.

  The cathode 200 includes a front end side metal member 200A including a front end surface 200S and a rear end side metal member 200B. And the groove part 100R which consists of a fine groove is formed at the time of the cutting which forms the taper surface 200Q.

  Further, after the formation of the fine groove r, a groove rr having a large pitch (hereinafter referred to as a wide groove) is formed by laser irradiation. The wide groove rr has a pitch P2 and a depth d '(not shown) that are sufficiently larger (millimeter order level) than the fine groove. Here, the pitch P2 is set in a range of 0.1 mm to 1.0 mm, and the depth d 'is set in a range of 0.1 to 0.5 mm. In particular, the pitch P2 is preferably set to 0.2 mm to 0.5 mm, and the depth d 'is set to 0.2 mm to 0.5 mm.

  The wide groove rr formed in the groove portion R by the laser irradiation after the cutting process enhances the electrode heat dissipation effect and further increases the bonding strength when the metal portion melted by the laser irradiation is buried in the wedge W.

  The fine groove is formed by a method other than the cutting process, and it is possible to form a fine groove / uneven surface that does not depend on peeling. What is necessary is just to form the groove | channel with moderate depth and a pitch in the range which joint surface intensity | strength raises. In particular, it is preferable to form a groove portion having a groove depth on the rear end side larger than the groove depth on the front end side.

  For example, the fine grooves may be formed at a pitch of 100 μm or less, and cutting may be performed so that the fine grooves have a depth of 100 μm or less with respect to the rear end side metal member. This is because the wedge W often occurs at the micro-order level, so that the wedge W cannot be sufficiently filled with a groove larger than the above.

  About the formation range of a groove part, it may be only a part of joint surface vicinity, or it can also carry out over the taper surface 20Q whole. Furthermore, wide grooves with a large pitch may be formed by a method other than laser irradiation (cutting or the like), or only fine grooves or wide grooves may be formed.

  About the metal material of the metal member 20A on the front end side and the metal member 20B on the rear end side, the metal member 20B is selected so as to have relatively higher extensibility than the metal member 20A. For example, the metal member 20B can be composed of tantalum / molybdenum or an alloy mainly composed of tantalum / molybdenum.

  In addition, you may comprise an electrode with three or more metal members, respectively. Further, only one of the electrodes may have a groove formed in the vicinity of the bonding surface, and the groove can be formed on the bonding surface formed on either the tapered surface or the cylindrical surface. Further, members other than metal members may be solid-phase bonded, and can be applied to discharge lamps other than short arc type discharge lamps.

  In the first and second embodiments, different metal members are solid-phase bonded, but the same kind of metal members can also be solid-phase bonded. Even if the spreadability of the metal member is the same, a minute wedge is likely to be formed on the joint surface, and the formation of the minute groove can prevent the wedge from expanding.

  Below, the Example of this invention is described using FIGS. 6-8.

  The cathode of the short arc type discharge lamp having a rated power of 5 kW is formed into a cathode shape by solid-phase joining a metal member made of tritunged tungsten and a metal member made of molybdenum in accordance with the SPS sintering method, and then cutting. The anode is obtained by solid-phase bonding and cutting a front end side metal member made of tungsten and a rear end side metal member made of molybdenum. The cathode has a total length of 20 mm, a distance from the cathode tip surface to the joining surface of 5 mm, and a joining surface diameter of 16 mm.

  FIG. 6 is a view showing a photograph of the cathode near the joint surface. FIG. 7 is a diagram showing an enlarged photograph of FIG. FIG. 8 is a view showing a photograph of the vicinity of the joint surface by an electron microscope.

  As is clear from FIG. 6, the groove is formed in the direction along the joint surface S1, and is formed in the front end side member 20A and the rear end side member 20B across the joint surface S1. Further, as is apparent from FIGS. 7 and 8, the rear end side member 20B has peeling.

  Since a groove was formed along the joint surface S1 and the rear end side member 20B was cut so as to cause peeling, no wedge-shaped gap was formed at the end of the joint surface, and the joint was not damaged during lighting. .

  Various changes, substitutions and alternatives are possible with respect to the present invention without departing from the spirit and scope of the present invention as defined by the appended claims. Furthermore, the present invention is not intended to be limited to the specific embodiments of the processes, apparatus, manufacture, components, means, methods, and steps described in the specification. Those skilled in the art will appreciate from the disclosure of the present invention devices, means, and methods that perform substantially the same functions as those provided by the embodiments described herein, or that provide substantially the same operations and effects. You will recognize it. Accordingly, the appended claims are intended to be included within the scope of such devices, means, and methods.

  This application claims the priority of a Japanese application (Japanese Patent Application No. 2013-151647, filed on July 22, 2013) as a basic application, and the disclosure including the specification, drawings and claims of the basic application is referred to. Which is incorporated herein by reference in its entirety.

DESCRIPTION OF SYMBOLS 10 Discharge lamp 12 Discharge tube 20 Cathode 30 Anode S1 Joint surface R Groove part r Fine groove rr Wide groove

Claims (7)

A discharge tube;
A pair of electrodes disposed in the discharge tube,
At least one of the electrodes is an electrode obtained by solid-phase bonding a front end side member and a rear end side member having higher extensibility than the front end side member,
A groove is formed on the electrode side surface across the joint surface between the front end side member and the rear end side member,
A discharge lamp, wherein a microscopic groove is formed on a side surface of a rear end side member of the groove. A discharge tube;
A pair of electrodes disposed in the discharge tube,
At least one of the electrodes is an electrode obtained by solid-phase bonding a front end side member and a rear end side member having higher extensibility than the front end side member,
A fine groove is formed on the electrode side surface across the joint surface between the front end side member and the rear end side member,
The discharge lamp characterized in that the fine groove is deeper on the side surface of the rear end side member than on the side surface of the front end side member. A discharge tube;
A pair of electrodes disposed in the discharge tube,
At least one of the electrodes is an electrode obtained by solid-phase bonding a front end side member and a rear end side member having higher extensibility than the front end side member,
A groove is formed on the electrode side surface across the joint surface between the front end side member and the rear end side member,
The discharge lamp characterized in that in the groove portion, a fine groove and a wide groove having a larger pitch and depth than the fine groove are formed across the joint surface. The discharge lamp according to any one of claims 1 to 3 , wherein the surface roughness Ra of the side surface of the rear end side member where the fine groove is formed is 1.2 µm or more. The discharge lamp according to any one of claims 1 to 4 , wherein a surface roughness Ra of a side surface of the tip side member in a portion where the fine groove is formed is 0.7 µm or less. A discharge tube;
A pair of electrodes disposed in the discharge tube,
At least one of the electrodes is an electrode obtained by solid-phase bonding a front end side member and a rear end side member having higher extensibility than the front end side member,
A groove is formed on the electrode side surface across the joint surface between the front end side member and the rear end side member,
The discharge lamp according to claim 1, wherein in the groove portion, the reflectance of the side surface of the rear end side member is smaller than the reflectance of the side surface of the front end side member. Solid-phase joining the front end side member and the rear end side member having higher extensibility than the front end side member,
A method of manufacturing a discharge lamp for cutting a side surface of an electrode member subjected to solid phase bonding,
In the cutting process, the discharge lamp manufacturing method of forming a groove on the side surface of the electrode member so as to straddle the joint surface between the front end side member and the rear end side member,
A manufacturing method of a discharge lamp, wherein fine grooves are formed on a side surface of a rear end side member during the cutting process.

Images