JP2015062202A - Extreme ultraviolet ray source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EUV (extreme ultraviolet) ray source device capable of transmitting vibration of a piezoelectric element to a fine hole plate, and to generate exactly a droplet of a target, while restraining sufficiently attenuation of amplitude and distortion of a waveform.SOLUTION: An EUV ray source device includes an EUV ray generation chamber 2, and a target substance supply part. A piezoelectric element 25 assists formation of a droplet 29 by abutting on a bottom face 22 and by imparting vibration to a capillary 28 via the bottom face, in the capillary 28 comprising a surrounding wall, a fine hole plate 23 having a micro-fine hole provided in an exit end of the surrounding wall, and the bottom face 22 connected to the surrounding wall and opposed to the piezoelectric element 25, for storing a target substance under a dissolved state, and for injecting the target substance from the micro-fine hole to form the droplet 29.

Description

  The present invention relates to an LPP (laser produced plasma) type EUV (extreme ultra violet) light source device for generating extreme ultraviolet light used for exposure of a semiconductor wafer, and more particularly, to target material in an extreme ultraviolet light generation chamber. The present invention relates to an extreme ultra violet light source device having an improved target material supply unit for injecting it.

  In recent years, miniaturization of circuit patterns has rapidly progressed in semiconductor integrated circuits, and fine processing of 30 nm node or less will be required within the next few years. There is an EUV light source using 13.5 nm light as a promising candidate of an exposure light source to satisfy the requirement. EUV light is obtained by converting a substance called a target into plasma. There are two types of methods for converting the target into plasma, that is, DPP (discharge produced plasma) using plasma generated by discharge and LPP (laser produced plasma) using plasma generated by a laser beam. In the LPP method, the laser is condensed with high density, and the target is turned into plasma by the energy.

  FIG. 12 is a diagram showing an outline of an example of a conventional LPP type EUV light source device. As shown in FIG. 12, the EUV light source apparatus includes a driver laser 101, an EUV light generation chamber 102, a target material supply unit 103, and a laser beam condensing optical system 104 as main components.

The driver laser 101 is an oscillation amplification type laser device that generates driving laser light used to excite a target material.
The EUV light generation chamber 102 is a chamber in which EUV light is generated. The EUV light generation chamber 102 is evacuated by a vacuum pump 105 in order to facilitate the plasma formation of the target material and prevent the EUV light from being absorbed. In addition, a window 106 for introducing laser light 120 generated from the driver laser 101 is attached to the EUV light generation chamber 102. Further, inside the EUV light generation chamber 102, a target injection nozzle 103a, a target collection cylinder 107, and an EUV light condensing mirror 108 are arranged.

  The target material supply unit 103 supplies a target material used for generating EUV light into the EUV light generation chamber 102 via a target injection nozzle 103 a that is a part of the target material supply unit 103. Among the supplied target materials, those which are no longer necessary without being irradiated with the laser light are recovered by the target recovery cylinder 107.

  The laser beam condensing optical system 104 includes a mirror 104a that reflects the laser beam 120 emitted from the driver laser 101 toward the EUV light generation chamber 102, and a mirror adjustment mechanism 104b that adjusts the position and angle (tilt angle) of the mirror 104a. And a condensing element 104c that condenses the laser light 120 reflected by the mirror 104a, and a condensing element adjustment mechanism 104d that moves the condensing element 104c along the optical axis of the laser light. The laser beam 120 condensed by the laser beam condensing optical system 104 passes through a hole formed in the central portion of the window 106 and the EUV light collector mirror 108 and reaches the trajectory of the target material. Thus, the laser beam condensing optical system 104 condenses the laser beam 120 so as to form a focal point on the trajectory of the target material. As a result, the target material 109 is excited and turned into plasma, and EUV light 121 is generated.

  The EUV light collecting mirror 108 is, for example, a concave mirror in which a Mo / Si film that reflects light of 13.5 nm with high reflectivity is formed on the surface thereof, and reflects the generated EUV light 121 to generate IF (intermediate). Condensed at the focusing point. The EUV light 121 reflected by the EUV light collector mirror 108 includes unnecessary light (electromagnetic wave (light wave having a wavelength shorter than that of the EUV light) among the light generated from the gate valve 110 provided in the EUV light generation chamber 102 and plasma. ), Light having a wavelength longer than that of EUV light (for example, ultraviolet light, visible light, infrared light, etc.) is removed, and it passes through a filter 111 that transmits only desired EUV light (for example, light having a wavelength of 13.5 nm). The EUV light 121 condensed at the IF (intermediate condensing point) is then guided to an exposure machine or the like via a transmission optical system.

  The target is a molten metal such as Sn or Li. Such a target material is melted by a target generation device, extruded from a fine hole of about several tens of μm by an inert gas such as Ar, and conveyed to a laser condensing point. The molten metal extruded from the fine holes is initially in a streak-like state, but becomes a non-constant lump from a certain distance. However, when a certain vibration is applied to the streaky molten metal column, the molten metal column pushed out from the fine hole changes into a spherical lump (called a droplet) having a certain size from a certain distance. Therefore, by applying appropriate vibrations to the fine holes, desired molten metal droplets are formed and irradiated with a CO2 laser or the like at the focal point to generate plasma. When the light emitted from the generated plasma is reflected by a condenser mirror that selectively reflects light having a wavelength of 13.5 nm, the selected extreme ultraviolet (EUV) light propagates to the exposure machine side.

Since EUV light is absorbed by oxygen or the like, the above process is performed in a vacuum chamber.
Note that the molten metal irradiated to the laser becomes debris in a neutral or ionic state and spreads in all directions. In order to minimize the generation of this debris, it is preferable that the amount of molten metal irradiated to the laser is set to an amount sufficient to obtain desired EUV light.

  Patent Document 1 discloses a target generation apparatus that generates droplets with uniform grains by transmitting vibrations of a piezo element to a side wall of a target injection nozzle. 13 and 14 are an elevation view and a plan view showing a cross section of the target injection nozzle disclosed in Patent Document 1. FIG. The target container 200 of the disclosed target generation apparatus is filled with a target such as molten metal, and the target is injected into the vacuum chamber from the pore 204 at the lower end of the target container. A plurality of piezo elements 206 are in contact with symmetrical positions across the heat insulating material 210 on the belly portion of the side wall 202 of the target container 200, and by vibrating the piezo elements 206, the vibration is generated in the target container 200. It is transmitted to the side wall 202. The target ejected from the pore 204 becomes a spherical droplet having substantially the same size from a position depending on a certain distance due to the vibration of the target container 200.

  A resistor film such as molybdenum is formed on the outer side of the side wall 202 of the target container 200 to form a heating body 214 that maintains the melting temperature of the target. When using tin as a target, it is necessary to maintain the target temperature in the range of 300 ° C to 400 ° C. On the other hand, since many piezo elements have a Curie point of 100 ° C. or lower, a heat insulating material 210 is interposed between the piezo element 206 and the target container 200 so that the heat of the target container 200 functions as the piezo element 206. I try not to damage it. In addition, in order to grip a part constituting the target injection nozzle in a fixed position and reliably transmit the vibration of the piezo element 206 to the side wall 202, a grip member 218 that surrounds the outside of the piezo element 206 and supports it while applying pressure. It has. The holding member 218 is provided with a cooling path 220 for circulating a cooling medium therein, and cools the piezo element 206.

  The target generation device disclosed in Patent Document 1 is configured such that each of the piezo elements 206 can be driven independently, and when a foreign object adheres to the target container side wall 202, the piezo element 206 at a symmetrical position can be expanded and contracted. By driving so as to be reversed, the target container side wall 202 can be moved violently at an arbitrary position in the circumferential direction, and the foreign matter can be easily separated and discharged.

  According to the disclosed invention, the heat insulating material 210 is interposed between the piezo element 206 and the heating body 214 of the target container 200, and the grip member 218 including the cooling path 220 is brought into close contact with the outside of the piezo element 206. Even if a piezo element having a low Curie point is used, strong vibration is applied to the target container 200 without impairing the performance of the piezo element, and even if a fixed substance is generated on the inner wall, it can be easily separated and eliminated. However, since the heat insulating material 210 is interposed between the target container 200 and the piezoelectric element 206, the vibration transmitted to the target container 200 is attenuated and the vibration waveform is broken. Further, in order to compensate the attenuation and transmit sufficient vibration, it is necessary to increase the vibration of the piezo element 206, and the deterioration of the piezo element is promoted.

  FIG. 15 is a block diagram showing a vibration part of a conventional droplet generating apparatus that has been used by the applicant. The nozzle portion 301 provided at the tip of the target injection nozzle is provided with a thin tube 303 serving as a flow path for a target supplied from a target storage unit (not shown), and a fine hole is provided at the tip of the thin tube 303. A pore plate 304 is provided. The nozzle portion 301 is heated to a temperature equal to or higher than the melting point of the target material. In order to vibrate the pore plate 304, a piezo element 306 is disposed in the vicinity of the pore plate 304. Since the piezo element 306 does not vibrate when the temperature is equal to or higher than the Curie temperature, it is necessary to keep the temperature at least at or below the Curie point, preferably at or below 1/2 the Curie point. Therefore, the heat flow from the high-temperature nozzle unit 301 is blocked by the heat insulating material 305, and the heat generated in the piezo element 306 is removed by the coolant 308 that can be cooled with water or the like through the cooling water pipe 320.

  The heat insulating material 305 is formed of a resin or ceramic material having low thermal conductivity. Since the heat insulating material 305 formed using a resin-based material has lower rigidity than metal, the vibration of the piezo element 306 is absorbed by the heat insulating material, and the amplitude of vibration transmitted to the pore plate 304 is reduced. On the other hand, the heat insulating material 305 formed using a ceramic material is brittle and difficult to handle, and the vibration transmitted to the pore plate 304 is attenuated and the waveform is distorted.

  FIG. 16 is a graph showing the amount of displacement in the vibration measured in the vicinity of the piezoelectric element 306 and the vibration measured in the vicinity of the pore plate 304. As can be seen from the figure, the amplitude is attenuated and the vibration waveform is distorted in the process in which vibration is transmitted from the piezoelectric element 306 to the pore plate 304. A certain amount of amplitude is required to generate droplets. Therefore, when the attenuation due to transmission increases, it is necessary to increase the vibration of the piezo element. Thereby, deterioration of the piezo element is accelerated. In addition, problems such as the droplet shape and generation timing becoming unstable due to distortion of the vibration waveform were clarified.

U.S. Pat. No. 7,378,673

  Therefore, the problem to be solved by the present invention is an extreme case where the vibration of the piezo element is transmitted to the pore plate while sufficiently suppressing the attenuation of the amplitude and the distortion of the waveform, and the droplet of the target material is generated accurately. An ultraviolet light source device is provided.

  In order to solve the above problems, an extreme ultraviolet light source apparatus according to the present invention is an extreme ultraviolet light source apparatus that generates extreme ultraviolet light by converting a target material into plasma by irradiating a droplet of the target material with laser light. A target material supply unit having a chamber in which extreme ultraviolet light is generated and a nozzle unit for injecting the target material into the chamber, and a pore plate with micropores attached to the end of the nozzle unit A target material supply unit formed with a narrow tube for storing the target material, a bottom surface directly connected to the narrow tube, and a vibration surface bonded to the bottom surface of the nozzle unit, and directly from the vibration surface to the bottom surface of the nozzle unit Piezoelectric elements that generate droplets of the target material that drops regularly by transmitting vibrations and vibrating the capillary tube, and emit laser light Includes a laser light source, an optical system for irradiating a laser beam emitted from the laser light source to the droplet of the target material, the.

  Note that a protrusion may be provided on the bottom surface so that the piezoelectric element is in direct contact with the protruded surface. Furthermore, it is preferable to arrange a member having a cooling mechanism at a position opposite to the bottom surface with the piezoelectric element interposed therebetween. A vibration may be transmitted by bonding a rigid member to the vibration surface of the piezo element and bonding the rigid member to the bottom surface. The rigid member preferably has a larger contact area with the piezo element than a contact area with the bottom surface. Further, the rigid member may be provided with a cooling mechanism. The piezo element preferably contains any one of PZT, AlN thin film, crystal, lithium niobate, lead titanate, lead metaniobate, gallium phosphate, langasite, and zinc oxide.

  According to the present invention, since the vibration of the piezo element is directly transmitted to the bottom surface facing the piezo element to vibrate the capillary tube, it is possible to suppress the attenuation of the vibration amplitude and the distortion of the waveform as much as possible. it can. Therefore, droplets are regularly generated, plasma is generated at a certain position, and stability of EUV intensity in IF is improved.

It is a schematic diagram which shows the outline | summary of the extreme ultraviolet light source device (EUV light source device) which concerns on 1st Embodiment of this invention. It is an enlarged view of the nozzle part terminal part of a 1st embodiment. It is a schematic diagram which shows the outline | summary of the EUV light source device which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the EUV light source device which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the EUV light source device which concerns on 4th Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the EUV light source device which concerns on 5th Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the EUV light source device which concerns on 6th Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the EUV light source device which concerns on 7th Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the EUV light source device which concerns on 8th Embodiment of this invention. It is a plane schematic diagram which shows the outline | summary of the EUV light source device which concerns on 9th Embodiment of this invention. It is a plane schematic diagram which shows the outline | summary of the EUV light source device which concerns on 10th Embodiment of this invention. It is a figure which shows the outline | summary of the conventional LPP type EUV light source device. It is elevation surface sectional drawing of the target injection nozzle disclosed by patent document. It is a plane sectional view of a target injection nozzle indicated by patent documents 1. It is a block diagram which shows the vibration part of the conventional droplet production | generation apparatus. It is a graph which shows the displacement amount in the vibration measured near the piezoelectric element, and the vibration measured near the pore plate.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.

(First embodiment)
FIG. 1 is a configuration diagram showing an outline of an EUV light generation chamber portion of an extreme ultraviolet light source device (hereinafter also referred to as “EUV light source device”) according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a nozzle end portion. FIG.
This EUV light source apparatus includes a driver laser, a laser beam condensing optical system, an EUV light generation chamber, a target material supply unit, and an EUV light condensing optical system as main components.

  The driver laser 13 is an oscillation amplification type laser device that generates driving laser light used to excite a target material. The EUV light generation chamber 11 is a chamber in which EUV light is generated. In addition, a window 15 for introducing laser light generated from the driver laser 13 is attached to the EUV light generation chamber 11. Further, inside the EUV light generation chamber 11, a laser light condensing optical system, a target injection nozzle, and an EUV light condensing mirror 19 are arranged.

  The laser beam condensing optical system includes a condensing mirror 17 that reflects the laser beam emitted from the driver laser 13 in the direction of the EUV light generation chamber 11. The laser light condensed by the laser light condensing optical system passes through a hole formed in the central portion of the EUV light condensing mirror 19 and is condensed so as to form a focal point on the trajectory of the target material. Thereby, the droplet 29 of the target material supplied from the nozzle part 21 is excited and turned into plasma, and EUV light is generated.

  The target material supply unit supplies a target material used for generating EUV light into the EUV light generation chamber 11 via a target injection nozzle. In the nozzle portion 21 provided at the tip of the target injection nozzle, a narrow tube 28 serving as a flow path of a molten metal serving as a target is formed inside, and a pore plate 23 having a fine hole 24 formed at the tip of the narrow tube 28 is provided. ing. In order to maintain the target material in a molten state, the main body of the nozzle portion 21 is heated to a temperature close to or higher than the melting point of the target material.

  Further, in order to vibrate the narrow tube 28 or the pore plate 23, the piezoelectric element 25 is arranged with the vibration surface in direct contact with the bottom surface 22 facing the piezoelectric element 25 in the vicinity of the pore plate 23. In order to reliably transmit the vibration of the piezo element 25 to the nozzle portion 21, the pressing member 27 surrounds the piezo element 25 and is fixed to the bottom surface 22 to apply a pressing pressure to the piezo element 25. Since the piezoelectric effect does not occur when the piezo element 25 is equal to or higher than the Curie temperature, it is preferable to use a piezo element having a Curie point higher than the melting temperature of the target, preferably a piezo element having a Curie point twice or more the melting temperature.

  For the target, a molten metal such as Sn or Li is used. Such a target material is melted by a target generation device, extruded from fine holes 24 of about several tens of μm in the pore plate 23 by an inert gas such as Ar, and conveyed to a laser condensing point. The molten metal extruded from the fine holes 24 initially forms the streak-like column 30, but becomes a droplet 29 from a certain distance. Here, when high-frequency vibration is generated by the piezo element 25, the molten metal column body 30 pushed out from the fine hole 24 changes to a spherical droplet 29 having a certain size from a certain distance.

The droplet 29 is irradiated with a CO2 laser at a condensing point to generate a plasma 31. When the light emitted from the generated plasma 31 is reflected by the EUV light condensing mirror 19 that selectively reflects light having a wavelength of 13.5 nm, the selected EUV light is collected at an IF (intermediate condensing point) 33. Light is transmitted to the exposure machine side.
Note that the molten metal irradiated to the laser becomes debris in a neutral or ionic state and spreads in all directions. In order to minimize the occurrence of this debris, it is preferable to adjust the size of the droplet 29 irradiated to the laser so that the target amount is sufficient to obtain the desired EUV light.

  In the EUV light source apparatus of the present embodiment, the nozzle portion 21 including the piezo element 25 is installed in the EUV chamber 11 in a vacuum state. The target material emitted from the pore plate 23 becomes plasma 31 at the condensing point of the laser. The light generated from the plasma 31 is sent to the IF 33 by the EUV light collector mirror 19 and then guided to the exposure machine side. In FIG. 1, the piezo element 25 is directly installed on the bottom surface 22 of the high temperature nozzle unit 21 facing the EUV chamber 11, and does not include a heat insulating material or the like that absorbs vibration. Therefore, amplitude attenuation and waveform distortion in the transmitted vibration can be suppressed as much as possible. Thereby, since the plasma 31 is stably generated at a certain position, the stability of the EUV intensity at the IF 33 is improved. In order to suppress vibration attenuation and distortion in the nozzle body 21 main body, the nozzle section 21 main body is preferably configured using a metal having high rigidity such as stainless steel.

  In FIG. 1, the piezo element 25 has a considerably high temperature in consideration of the temperature of the nozzle unit 21 body and the self-heating of the piezo element 25. Therefore, a piezo element that has a high Curie point and can operate normally at high temperatures is required. PZT (lead zirconate titanate), which is most popular as a piezo element, has a Curie point in the range of about 150 ° C to 350 ° C depending on the composition. It is not preferable to install and use it directly on the high-temperature nozzle unit 21 that handles metal.

In this embodiment, for example, an aluminum nitride (AlN) thin film that can be used at 1200 ° C, a crystal having a Curie point of 573 ° C, a lithium niobate having a Curie point of 1210 ° C, a lead titanate having a Curie point of 490 ° C, A piezo element composed of lead metaniobate having a Curie point of 570 ° C., gallium phosphate stable to 950 ° C., or langasite having a Curie point of 1400 ° C. is preferable. Note that PZT having a composition with a high Curie point can also be used, and zinc oxide that can be used up to 300 ° C. may be used.
In addition, the power supply unit or electrode for driving the piezo element 25 cannot be soldered due to the temperature relationship, so it is necessary to provide a contact or braze mechanically.

  Note that when high frequency vibration is generated in the piezo element 25, the phenomenon that the molten metal column 30 flowing down from the fine hole 24 changes into a regular spherical droplet 29 from a certain distance is not necessarily large amplitude vibration. It is known that it is caused by applying a vibration having a smooth sine waveform with a constant period. For example, if there is an amplitude of 600 to 800 pm, a sufficiently effective droplet can be formed. In the EUV light source device of the present embodiment, there is no inclusion between the piezo element 25 and the bottom surface 22 of the nozzle portion 21, so that there is no inclusion that tends to break the waveform during vibration propagation. Is transmitted to the nozzle unit 21 as it is, so that droplets of a predetermined size can be generated at predetermined intervals.

(Second Embodiment)
FIG. 3 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the second embodiment of the present invention. The EUV light source device of the present embodiment is substantially the same in other configurations except that a high vibration transmission member is added to the nozzle portion 21 of the first embodiment.

  In order to use it for holding the piezoelectric element 25, a component may be required between the piezoelectric element 25 and the nozzle portion 21. At this time, the vibration attenuation or waveform is provided by interposing the high vibration transmitting member 35 that easily transmits vibration without using a heat insulating material between the piezoelectric element 25 and the bottom surface 22 of the nozzle portion 21 as in the prior art. Can be suppressed, and droplets can be generated regularly to generate stable EUV light. As a material that easily transmits vibration, a highly rigid metal can be cited. Examples thereof include stainless steel alloys, iron metals such as carbon steel, and Ni alloys such as Inconel and Hastelloy. However, since the piezo element 25 is not forcibly cooled, it is desirable to use a piezo element that can be used at a high temperature as used in the first embodiment.

(Third embodiment)
FIG. 4 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the third embodiment of the present invention. The EUV light source device of this embodiment is substantially the same in other configurations, except that a cooling plate 37 charged with a cooling tube 39 is added to the nozzle unit 21 of the first embodiment.

  In the present embodiment, the operating temperature of the piezo element 25 is lowered without cooling the nozzle portion 21 by cooling the opposite side of the piezo element 25 to the high temperature nozzle portion 21 with the cooling plate 37. As a result, various elements including PZT having a low Curie point can be used. The cooling plate 37 is made of a material having high thermal conductivity and high rigidity, and is provided with a cooling pipe 39 therein so that a coolant such as water whose temperature is controlled by a temperature adjusting device or the like circulates. . In order to further enhance the cooling effect, the cooling plate 37 is installed so as to cover all surfaces of the pressing member 27 that surrounds the piezoelectric element 25 and applies pressure to the piezoelectric element and that is not in contact with the high-temperature structure. As a result, the contact area with the cooling plate 37 can be increased and cooling can be effectively performed.

  The temperature of the cooling plate 37 is set to a temperature that satisfies two requirements: (1) the temperature at which the piezo element 25 can operate or less, and (2) the nozzle unit 21 body, which is a high-temperature structure. Further, in order to carry out temperature management, it is necessary to measure the temperature of the nozzle portion 21 of the high-temperature structure, the piezo element 25, and the cooling plate 37 with a thermocouple, a resistance temperature detector, a fiber thermometer, or the like. As a typical case, when PZT is used for the piezo element and tin Sn is used for the target material, the temperature of the cooling plate 37 is controlled so that the high-temperature structure is 260 ° C. or higher and the piezo element is 100 ° C. or lower. Moreover, the piezoelectric element enumerated in description of 1st Embodiment and usable at high temperature may be sufficient. However, even if the temperature of the high-temperature structure portion in contact with the piezo element 25 is 260 ° C. or less, the influence of the temperature of the contact portion is small when the molten metal is separated from the portion to some extent (because the molten metal does not solidify). ) Can be set lower. For example, the aforementioned 260 ° C. may be 200 ° C. in some cases.

(Fourth embodiment)
FIG. 5 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the fourth embodiment of the present invention. The EUV light source device of the present embodiment differs from the nozzle portion 21 of the first embodiment in that a cooling tube 43 is charged in the pressing member 27 and a heat insulating member 45 is provided so that the high-temperature structure is not cooled. However, the other configurations are almost the same.

  The nozzle portion of the present embodiment is characterized by a structure in which a cooling pipe 43 is provided on a pressing member that applies pressure to the piezo element 25 and the refrigerant is directly passed therethrough. Thereby, the cooling efficiency of the piezo element 25 increases. In addition, since the pressing member 41 with cooling and the nozzle part 21 became near, there exists a possibility that the nozzle part 21 may be cooled excessively. Therefore, by inserting a heat insulating member 45 between the pressing member 41 with cooling and the nozzle portion 21, the temperature of the high-temperature object such as the nozzle portion 21 is kept high.

(Fifth embodiment)
FIG. 6 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the fifth embodiment of the present invention. The EUV light source device of the present embodiment is provided with a protrusion 47 that transmits vibration of the piezo element 25 on the bottom surface 22 of the nozzle portion 21 with respect to the nozzle portion 21 of the third embodiment shown in FIG. The other configurations are substantially the same except that the piezo element 25 is brought into contact with the portion 47.

  As shown in FIG. 6, in this embodiment, the protrusion 47 of the nozzle portion 21 that transmits vibration in contact with the piezo element 25 is formed in a wedge shape so that the cross-sectional area decreases as it approaches the bottom surface 22. It is constricted to limit the heat flow rate at a position where it is connected to the bottom surface 22. Thereby, the vibration of the piezo element 25 can be efficiently transmitted to the nozzle portion 21 and the inflow / outflow of heat from the piezo element 25 can be suppressed. Furthermore, the cooling plate 37 having the cooling pipe 39 is disposed so as to contact the back of the pressing member 27 that applies pressure to the piezoelectric element, and the piezoelectric element 25 is cooled from the pressing member 27 side, The temperature control of the piezo element 25 can be easily performed.

(Sixth embodiment)
FIG. 7 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the sixth embodiment of the present invention. In the EUV light source device of the present embodiment, a heat insulating member 51 is inserted between the pressing member 27 and the bottom surface 22 of the nozzle portion 21 with respect to the nozzle portion 21 of the fifth embodiment shown in FIG. The other configurations are substantially the same except that the temperature decrease and the temperature increase of the pressing member 27 are suppressed. The heat insulating member 51 can suppress the temperature drop of the high-temperature nozzle portion 21 that melts the metal, and can suppress the temperature rise of the pressing member 27 that needs to be cooled because the piezo element 25 is not heated.

(Seventh embodiment)
FIG. 8 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the seventh embodiment of the present invention. The EUV light source device of the present embodiment is cooled by a high vibration transmission member 35 interposed between the piezoelectric element 25 and the bottom surface 22 of the nozzle portion 21 with respect to the nozzle portion 21 of the second embodiment shown in FIG. The other configurations are almost the same except that the pipe 53 is attached.

  By lowering the temperature of the high vibration transmission member 35, a piezoelectric element that is used at a relatively low temperature such as PZT can be used. The temperature of the high-vibration transmission member 35 is set to a temperature that satisfies two requirements: (1) the temperature at which the piezo element 25 can operate, or (2) the nozzle portion 21 body that is a high-temperature structure is at or above a desired temperature. Moreover, in order to implement temperature management, it is necessary to measure the temperature of the nozzle portion 21 of the high-temperature structure, the piezo element 25, and the high vibration transmission member 35 with a thermocouple, a resistance temperature detector, a fiber thermometer, or the like.

(Eighth embodiment)
FIG. 9 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the eighth embodiment of the present invention. The EUV light source device of the present embodiment differs from the nozzle portion 21 of the seventh embodiment shown in FIG. 8 only in that a cooling plate 37 charged with a cooling tube 39 is added, and other components are almost the same. The same. In addition to the seventh embodiment, the piezo element 25 can be more efficiently cooled by cooling from the pressing member 27 side. In this case, the temperature of the high vibration transmission member 35 and the cooling plate 37 may be the same, but by giving a temperature difference such that the cooling plate temperature <the high vibration transmission member temperature, the piezo element is not affected by the nozzle portion 21. 25 can be cooled.

(Ninth embodiment)
FIG. 10 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the ninth embodiment of the present invention. The EUV light source device according to the present embodiment is provided with a high vibration transmission member 55 equivalent to the protrusion 47 integrally formed on the bottom surface 22 of the nozzle portion 21 with respect to the nozzle portion 21 according to the fifth embodiment shown in FIG. The other configurations are substantially the same except that the piezoelectric element 25 is joined to the vibration surface of the piezoelectric element 25 and is interposed between the bottom surface 22 and the vibration surface of the piezoelectric element 25.

  The side opposite to the nozzle portion of the piezo element 25 is cooled by the cooling plate 37 via the pressing member 27. Further, when the ground contact area between the high vibration transmission member 55 and the nozzle portion 21 is reduced, the heat flux passing through the high vibration transmission member 55 can be reduced. For example, the high vibration transmission member 55 (thermal conductivity 20 [W / (m · K)]) provides the same heat flux as the heat insulating material (thermal conductivity 0.1 [W / (m · K)]). If so, the installation area may be reduced to 1/200. If the shape of the ground plane is circular, the radius may be reduced to about one-fourth. The configuration and set temperature of the cooling plate 37 are the same as in the third embodiment.

(10th Embodiment)
FIG. 11 is a configuration diagram showing an outline of a nozzle portion in an EUV light source apparatus according to the tenth embodiment of the present invention. The EUV light source device of the present embodiment incorporates a cooling pipe 57 into a high vibration transmission member 55 interposed between the bottom surface 22 and the piezoelectric element 25 with respect to the nozzle portion 21 of the ninth embodiment shown in FIG. Other than that, the other configurations are almost the same.

  The piezoelectric element 25 is also cooled by the high vibration transmission member 55 on the nozzle portion 21 side. As in the seventh embodiment, the temperature of the high-vibration transmission member 55 is (1) below the temperature at which the piezo element 25 can operate, and (2) the nozzle unit 21 body, which is a high-temperature structure, is above the desired temperature. The temperature satisfies two requirements. Since the EUV light source device of the present embodiment has poor heat conduction between the high vibration transmission member 55 and the nozzle portion 21, the influence on the nozzle portion 21 is small even if the cooling temperature of the high vibration transmission member 55 is lowered. The temperature of 25 can be further lowered.

  The present invention is applied to an LPP type EUV light source device that generates extreme ultraviolet light for exposing a semiconductor wafer or the like, thereby suppressing vibrations of the piezoelectric element to the pore plate while sufficiently suppressing attenuation of amplitude and distortion of waveform. It can transmit and generate regular droplets, and can emit extreme ultraviolet light with high efficiency.

DESCRIPTION OF SYMBOLS 11 ... EUV light generation chamber, 13 ... Driver laser, 15 ... Window, 17 ... Condensing mirror, 19 ... EUV light condensing mirror, 21 ... Nozzle part, 22 ... Bottom, 23 ... Porous plate, 24 ... Micropore, 25 ... Piezo element, 27 ... Pushing member, 28 ... Thin tube, 29 ... Droplet, 30 ... Streaky column, 31 ... Plasma, 33 ... IF (intermediate focusing point), 35 ... High vibration transmission member, 37 ... Cooling plate, 39 ... cooling pipe, 43 ... cooling pipe, 45 ... heat insulating member, 47 ... protrusion, 51 ... heat insulating member, 53 ... cooling pipe, 55 ... high vibration transmission member, 57 ... cooling pipe, 101 ... driver laser, DESCRIPTION OF SYMBOLS 102 ... EUV light generation chamber, 103 ... Target material supply part, 103a ... Target injection nozzle, 104 ... Laser beam condensing optical system, 104a ... Mirror, 104b ... Mirror adjustment mechanism, 104c ... Collection Element 104d ... Condensing element adjusting mechanism 105 ... Vacuum pump 106 ... Window 107 ... Target recovery cylinder 108 ... EUV light condensing mirror 109 ... Target material 110 110 Gate valve 111 111 Filter 120 Laser Light, 121 ... EUV light, 200 ... Target container, 202 ... Side wall, 204 ... Fine pore, 206 ... Piezo element, 210 ... Insulating material, 214 ... Heating body, 218 ... Holding member, 301 ... Nozzle part, 303 ... Molten metal Channel, 304 ... pore plate, 305 ... heat insulating material, 308 ... coolant.

Therefore, an object of the present invention is to provide, while suppressed won the distortion of the amplitude attenuation and waveform to transmit vibrations of the piezoelectric element to the nozzle portion, extreme ultraviolet light source to accurately produce droplets of the target material Is to provide a device.

To solve the above problems, the extreme ultraviolet light source device according to one aspect of the present invention, the laser beam by irradiating a target substance, in an extreme ultraviolet light source device that generates extreme ultraviolet light to the target material into a plasma there, a chamber is generated in the extreme ultraviolet light is performed, is melted, the target material that has been under pressure by inert gas, is supplied into the chamber by the pressure, with a nozzle portion which micropores are formed a target material supply unit, disposed in the nozzle portion, and the heat transfer El piezoelectric element vibration to the nozzle portion, an optical system for irradiating a laser beam emitted from the laser light source to a target substance, the first connected to the piezoelectric element And a member having a second surface connected to the nozzle portion .

According to one aspect of the present invention, Rukoto to prevent the Runode be transmitted directly to the vibration of the piezoelectric element on the bottom facing the piezoelectric element, the amplitude of the vibrations or cause distortion of the waveform or attenuated Can do. Therefore, droplets are regularly generated, plasma is generated at a certain position, and stability of EUV intensity in IF is improved.

Claims (7)

An extreme ultraviolet light source device that generates extreme ultraviolet light by irradiating a droplet of a target material with a laser beam to convert the target material into plasma,
A chamber in which extreme ultraviolet light is generated;
A target material supply unit comprising a nozzle unit for injecting a target material into the chamber, wherein a fine plate in which fine holes are formed is attached to the end of the nozzle unit to store the target material; The target material supply unit formed with a bottom surface directly connected to the narrow tube;
It has a vibration surface joined to the bottom surface of the nozzle part, and generates a droplet of a target material to be regularly dropped by transmitting vibration from the vibration surface to the bottom surface of the nozzle part to vibrate the capillary tube. Piezo element,
A laser light source for emitting laser light;
An optical system for irradiating a droplet of a target material with laser light emitted from the laser light source;
An extreme ultraviolet light source device comprising:   The extreme ultraviolet light source device according to claim 1, wherein a projection is provided on the bottom surface and the vibration surface of the piezo element is joined to a surface of the projection.   The extreme ultraviolet light source device according to claim 1, wherein the piezo element transmits vibration by joining a rigid member to a vibration surface and joining the other end surface of the rigid member to the bottom surface as the vibration surface.   The extreme ultraviolet light source device according to claim 3, wherein the rigid member has a contact area with the vibration surface of the piezoelectric element larger than a contact area with the bottom surface.   The extreme ultraviolet light source device according to claim 3, wherein the rigid member includes a cooling mechanism.   The extreme ultraviolet light source device according to claim 1, wherein a member having a cooling mechanism is disposed at a position opposite to the bottom surface with the piezoelectric element interposed therebetween.   The piezo element includes any one of PZT, AlN thin film, crystal, lithium niobate, lead titanate, lead metaniobate, gallium phosphate, langasite, and zinc oxide. The extreme ultraviolet light source device according to claim 1.

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