JP2008293738A - Euv light generating device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EUV light generating device in which device cost is kept low, energy transfer efficiency is improved, and an EUV light output can be obtained stably without variations in energy by eliminating the displacement of droplet positions. <P>SOLUTION: The droplet supply means 6 supplies a droplet 1A including a metal or a metal compound as a target 1 to an EUV light generating point A along a supply passage 1B. The droplet heating means 7 has a heat source 7a arranged around the supply passage 1B of the droplet 1A, and heats the droplet 1A by radiant heat radiated from the heat source 7a. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an EUV light generation apparatus used for a light source such as an exposure apparatus, and more particularly to an apparatus for supplying a target that is a generation source of EUV light.

  An optical lithography technique for optically transferring a circuit pattern onto a semiconductor wafer is important for LSI integration. As an exposure apparatus used for photolithography, an apparatus using a reduction projection exposure method called a stepper is mainly used. That is, a transmitted light of an original image (reticle) pattern illuminated by an illumination light source is projected onto a photosensitive material on a semiconductor substrate by a reduction projection optical system to form a circuit pattern. The resolution of this projected image is limited by the wavelength of the light source used. For this reason, the wavelength of the light source is gradually shortened to the ultraviolet region in accordance with the demand for further miniaturization of the pattern line width.

  In recent years, KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm) that oscillates light in the deep ultraviolet region (DUV light) is used as a light source, or F2 laser that oscillates light in the vacuum ultraviolet region (VUV light). (Wavelength 157 nm) has been developed as a light source.

  At present, an attempt is made to use an EUV light source (wavelength: 13.5 nm) that outputs light in the extreme ultraviolet region (hereinafter referred to as EUV light) as a light source for photolithography in order to perform further fine processing.

  The methods for generating EUV light are roughly classified into an LPP (laser-generated plasma) method and a DPP (discharge generated plasma) method. In the LPP type EUV light source, the target is irradiated with a short pulse laser beam to excite the target into a plasma state to generate EUV light, which is condensed by a condenser lens and output to the outside. . On the other hand, in a DPP type EUV light source, a target gas is introduced between both electrodes and a voltage is applied between both electrodes to excite the target into a plasma state between both electrodes to generate EUV light. The light is condensed by a condensing lens and EUV light is output to the outside.

  Hereinafter, the LPP method will be described as a representative.

  FIG. 1 conceptually shows the configuration of an EUV light generation apparatus based on the LPP method used as a light source of an exposure apparatus.

  A condensing mirror 3 for condensing EUV light is provided inside the vacuum chamber 2. The EUV light condensed by the condenser mirror 3 is transmitted to an exposure apparatus (not shown) outside the vacuum chamber 2. In the exposure apparatus, a semiconductor circuit pattern is formed on a semiconductor wafer using EUV light.

  The inside of the vacuum chamber 2 is evacuated by a vacuum pump or the like and is in a vacuum state. This is because EUV light has a short wavelength of 13.5 nm and does not propagate efficiently unless in a vacuum.

  The target 1 serving as an EUV light generation source is positioned at a predetermined EUV light generation point A in the vacuum chamber 2, that is, a laser beam condensing point. As the material of the target 1, tin Sn, lithium Li, xenon Xe, or the like is used.

In the driver laser device 4 as a laser oscillator, the laser beam L is pulse-oscillated and the laser beam L is emitted. As the laser, an Nd: YAG laser, a CO2 laser, or the like is used.

The laser light L is condensed at the EUV light generation point A through a condensing optical system. The laser beam L is applied to the target 1 at a timing when the target 1 is positioned at the EUV light generation point A. By irradiating the target 1 with the laser beam L, the target 1 is excited into a plasma state and EUV light is generated.

  The generated EUV light diverges in all directions around the plasma. The collector mirror 3 is disposed so as to surround the plasma. The EUV light that diverges in all directions is collected by the collecting mirror 3 and reflects the collected EUV light. The condensing mirror 3 selectively reflects a desired wavelength of 13.5 nm. The EUV light 5 (output EUV light) reflected by the condenser mirror 3 is propagated to the exposure apparatus.

  A part of the target 1 is split and scattered by debris due to a shock wave or the like when plasma is generated. The debris includes fast ions and residues of the target 1 that did not become plasma.

  The target 1 is roughly classified into a droplet (droplet) target, that is, a liquid target or a fixed target. In the case of a liquid target, for example, a metal such as tin Sn or lithium Li is melted at a high temperature and, for example, jetted or droplet-shaped from a fine hole such as a nozzle and ejected to the EUV light generation point A. In the case of a fixed target, the metal is wire-shaped or tape-shaped and fed to the EUV light generation point A, or the metal is disk-shaped or rod-shaped and rotated at the EUV light generation point A.

  The liquid target is a target that is a molten metal obtained by melting a metal or a metal compound, a target in which a metal or a metal compound is dissolved in a solvent such as methanol, or a target that is dispersed in a colloidal solution. being classified. In the former, the metal component or metal compound component in the droplet is 100%, but in the latter, the metal component or metal compound component in the droplet has a concentration according to the amount of the solvent.

  In recent years, a significant increase in the output of EUV light has been demanded. Accordingly, it has been required to use a high-power laser for the driver laser device 4 to maintain a high-power and stable output of EUV light for a long time.

  For example, in order to obtain EUV light with a high output of 50 W or more, the LPP method illustrated in FIG. 1 is more suitable than the DPP method.

  However, even when an LPP type EUV light generation apparatus is employed, the problem that debris is generated with the generation of EUV light as described above is unavoidable.

Debris is undesirable from the viewpoint of durability of the EUV light generation apparatus or efficiency of light output.

  That is, debris of fast ions collides with an optical device such as the condensing mirror 3 and scratches a smooth reflecting surface such as the condensing mirror 3 to impair the durability of the optical system. Further, when debris adheres to an optical device such as the condensing mirror 3, the reflectance of the EUV light is lowered, and the output of the EUV light is lowered. Further, the gasification of the debris reduces the degree of vacuum in the vacuum chamber 2, reduces the EUV light propagation efficiency, and decreases the EUV light output.

Consider the case of irradiating a liquid target with laser light.

  For example, even in the case of a droplet having a particle size of about 10 μm, the thickness of the target that contributes to the generation of EUV light is about a slight thickness (for example, 10 nm) of the surface of the droplet. The remaining material becomes debris.

  Therefore, comparing the case where the droplet is made of 100% metal and the case where the concentration of the metal is lowered by the solvent, if the particle size of the droplet is the same, the amount of metal that becomes debris Is advantageous in that the number of droplets of the latter metal solution is smaller and the formation of debris can be suppressed.

Therefore, for the purpose of reducing the generation amount of debris by supplying the minimum amount of target 1 to the EUV light generation point A irradiated with laser light, a metal composed of a molten metal or a molten metal compound Attempts have been made to use droplets such as metal solutions in which the concentration of the component of the metal or metal compound is lowered, instead of using droplets containing 100% of the component or metal compound component.

  In the following Patent Documents 1 and 2, in an LPP type EUV light generation apparatus, the generation of debris is suppressed by supplying a droplet of a metal solution or a droplet of a solution containing metal particles to the EUV light generation point A. The invention is described. In this case, although depending on the concentration of the metal component, the EUV light 5 can be stably generated at a metal component density lower by about 20% to 5% than when the molten metal is a droplet.

  However, when the metal solution is used as a droplet or when the solution containing metal particles is used as a droplet, solvent components other than the metal component that is the source of EUV light in the droplet are used as EUV light output. Influence. That is, the liquid components other than the metal in the droplets are scattered or evaporated in the vacuum chamber 2 by irradiation with the laser light L without contributing to the generation of the EUV light 5. Such scattered or evaporated matter of the solvent becomes debris and adheres to or damages the surface of the optical device such as the condenser mirror 3. As a result, the reflectance of the EUV light 5 is reduced.

  Further, the gas generated by the evaporation of the solvent stays in the vicinity of the plasma. The staying gas becomes an EUV light absorber. For this reason, the EUV light that can be effectively used is reduced, and the output of the EUV light is substantially reduced.

  Therefore, it is necessary to prevent solvent components other than the metal component in the droplets from being scattered or evaporated in the vacuum chamber 2 by the irradiation of the laser beam L. As one method for that, it is conceivable that the solvent component is removed from the droplet before the droplet reaches the EUV light generation point A.

Therefore, in Patent Documents 3 and 4 below, when a solution containing metal fine particles is supplied as a droplet toward the EUV light generation point A, the laser beam or the particle is emitted before the droplet reaches the EUV light generation point A. An invention is described in which the droplet is preliminarily heated by irradiating the droplet with the beam to promote evaporation or sublimation of the solvent in the droplet to remove the solvent component from the droplet.
USP 6862339 USP 6865255 JP 2004-288517 A JP 2006-210110 A

  Since the laser beam is highly condensable, when the droplet is preheated before it reaches the EUV light generation point A, energy is injected into the narrow space targeted by the droplet to evaporate the solvent. It is also effective as a method of sublimating.

  However, the laser has a problem that the apparatus cost is relatively high, and the conversion efficiency from electric input to laser output is as low as about 10%.

  Further, since the laser beam has good light condensing properties, the droplet is not uniformly heated when the laser beam is irradiated on one side of the droplet. For this reason, when the solvent in the droplet evaporates or sublimates, the position of the droplet may shift due to the reaction. As a result, when the EUV light generation point A is irradiated with the driver laser light L for plasma generation, the position of the droplet is deviated from the EUV light generation point A, and the output energy of the EUV light 5 varies. As described above, when the output energy of the EUV light 5 varies and the EUV pulse energy becomes unstable, there is a possibility that the semiconductor device cannot be stably produced with high quality.

  The present invention has been made in view of such circumstances, and suppresses the apparatus cost, improves the energy conversion efficiency, eliminates the positional deviation of the droplets, and stably stabilizes the EUV light without any variation in energy. The problem to be solved is to obtain an output.

The first invention is
In an EUV light generation apparatus in which EUV light is generated by making a target located at an EUV light generation point into a plasma state,
Droplet supplying means for supplying a droplet containing a metal or a metal compound as a target toward an EUV light generation point along the supply path;
A heat source is disposed around the supply path of the droplet, and a droplet heating means for heating the droplet by radiant heat radiated from the heat source is provided.

The second invention is the first invention,
The droplet heating means is a means for heating the droplet using a heat source as a lamp.

The third invention is the first invention,
The droplet heating means is a means for heating the droplet using a heat source as a wall surface.

A fourth invention is the second invention,
The lamp is characterized by being a halogen lamp, an arc lamp or an incandescent lamp.

The fifth invention is the second invention,
The lamp is arranged along the droplet supply path, and the intensity distribution of the radiant heat radiated from the lamp is wide in the direction along the droplet supply path and narrow in the direction perpendicular to the droplet supply path. It is characterized by becoming.

A sixth invention is the third invention,
The wall surface is heated by resistance heating or induction heating.

A seventh invention is the third invention,
The wall surface is a wall surface surrounding the droplet supply path, and the intensity distribution of the radiant heat radiated from the wall surface is wide in the direction along the droplet supply path and perpendicular to the droplet supply path. It is characterized by narrowing in the direction.

In an eighth aspect based on the first aspect,
A heating chamber in which the droplet is heated and a space in which EUV light is generated are separated by a partition having an opening through which the droplet passes.

A ninth invention is the first invention,
The droplet is a liquid metal, a metal solution, a metal compound solution, or a colloidal solution containing metal particles or metal compound particles.

The tenth invention is the first invention,
The main component of the metal is tin Sn or lithium Li.

The eleventh invention is the first invention,
The main component of the metal compound is tin oxide SnO2.

In a twelfth aspect based on the first aspect,
The main component of the solvent of the droplet is a dispersible liquid or organic solvent or water or liquid nitrogen or liquid xenon.

The thirteenth invention
An EUV light generation method in which a target located at an EUV light generation point is brought into a plasma state to generate EUV light,
Supplying a droplet containing a metal or a metal compound as a target toward an EUV light generation point along a supply path;
By radiating heat to the droplet, a part or all of the solvent constituting the droplet is removed, and the metal particles or metal compound particles are aggregated to a density lower than that of the solid metal or solid metal compound Or a step of dispersing the target in a certain space where the target can be in a plasma state;
And a step of bringing the target into a plasma state with the target being a space where metal particles or an aggregate of metal compound particles or metal particles or metal compound particles are dispersed.

As shown in FIG. 2, the first invention is premised on an EUV light generation apparatus 10 that generates EUV light by making a target 1 (droplet 1A) located at an EUV light generation point A into a plasma state.

  The droplet supply means 6 supplies a droplet 1A containing a metal or a metal compound as the target 1 toward the EUV light generation point A along the supply path 1B.

  The droplet heating means 7 has a heat source 7a disposed around the supply path 1B of the droplet 1A, and heats the droplet 1A with radiant heat radiated from the heat source 7a.

  In FIG. 3A, the droplet 1A including the metal particles 1C or the metal compound particles 1C ′ is preliminarily heated by the radiant heat radiated from the heat source 7a of the droplet heating means 7 around the supply path 1B. It is a figure which shows that the metal particle 1C or metal compound particle 1C 'became the state aggregated to the density lower than those solid density. In FIG. 3B, the droplet 1A including the metal particles 1C or the metal compound particles 1C ′ is preliminarily heated by the radiant heat radiated from the heat source 7a of the droplet heating means 7 around the supply path 1B. The metal particles 1C or the metal compound particles 1C ′ are in a state of being dispersed in a certain space where the target 1 can be in a plasma state.

  According to the first invention, as shown in FIG. 2, a droplet 1A containing a metal or a metal compound as a target 1 is supplied toward an EUV light generation point A along a supply path 1B.

Then, as shown in FIG. 3 (a), for example, a droplet 1A in a colloidal solution containing metal particles 1C or metal compound particles 1C ′ is supplied from a heat source 7a of the droplet heating means 7 around the supply path 1B. It is preliminarily heated by the radiant heat radiated. Thereby, all or a part of the solvent in the droplet 1A is removed, and the metal particles 1C or the metal compound particles 1C ′ are aggregated to a density lower than their solid density. Alternatively, as shown in FIG. 3B, the droplet 1A containing the metal particles 1C or the metal compound particles 1C ′ is preliminarily radiated from the heat source 7a of the droplet heating means 7 around the supply path 1B. To be heated. Thereby, all or a part of the solvent in the droplet 1A is removed, and the metal particles 1C or the metal compound particles 1C ′ are dispersed in a certain space where the target 1 can be brought into a plasma state.

In this way, all or a part of the solvent component other than the metal component in the droplet 1A is removed, and the droplet 1A in an aggregated state such as the metal particle 1C or a dispersed state such as the metal particle 1C becomes the EUV light generation point A. To reach. At the EUV light generation point A, the driver laser light L for plasma generation is irradiated onto the droplet 1A, and EUV light 5 is generated.

According to the first aspect of the invention, the laser light L is applied to the target 1A in which the solvent component is removed and the metal particles are agglomerated or dispersed. Therefore, the target from which the solvent component is not removed. Compared with the case where 1A is irradiated with the laser light L, the generation efficiency of the EUV light 5 is increased. That is, if there is a liquid component other than the metal in the droplet 1A, the liquid component does not contribute to the generation of the EUV light 5 and is scattered or evaporated in the vacuum chamber 2 by the irradiation of the laser light L. . Such scattered or evaporated matter of the solvent becomes debris and adheres to or damages the surface of the optical device such as the condenser mirror 3. As a result, the reflectance of the EUV light 5 is reduced. Further, the gas generated by the evaporation of the solvent stays in the vicinity of the plasma. The staying gas becomes an EUV light absorber. For this reason, the EUV light that can be effectively used is reduced, and the output of the EUV light 5 is substantially reduced. However, the droplet 1A from which the solvent component has been removed in advance does not cause such a decrease in the output of the EUV light 5.

Further, the replacement frequency of the expensive condenser mirror 3 is reduced. As a result, the operation cost of the EUV light generation apparatus 10 can be reduced and the operating rate can be improved.

In the first invention, the preliminary heating to the droplet 1 before the droplet 1A reaches the EUV light generation point A is performed not by irradiation with laser light but by radiant heat from the heat source 7a. Therefore, compared with the case where a laser is used, the apparatus cost can be kept low and the energy conversion efficiency becomes very high.

Further, as compared with the case where a laser is used, the entire droplet 1A is heated uniformly, so that the position of the droplet 1A is not shifted due to evaporation or sublimation of the liquid component. Therefore, it is possible to prevent the output energy of the EUV light 5 from being varied and the EUV pulse energy from becoming unstable due to the positional deviation of the droplet 1A at the EUV light generation point A. Thereby, it becomes possible to stably produce semiconductor devices with high quality.

As described above, according to the first invention, the apparatus cost is kept low, the energy conversion efficiency is improved, the position shift of the droplet 1A is eliminated, and the EUV light output is stably obtained with no energy variation. Be able to.

The present invention can be applied not only to an LPP type EUV light generation apparatus, but also to a DPP type EUV light generation apparatus in which a target is introduced between both electrodes.

In the second invention, as shown in FIG. 4, the heat source 7a is a lamp, and the droplet 1A is heated by the radiant heat radiated from the lamp 7a.

In the third invention, as shown in FIG. 8, the heat source 7a is a wall surface, and the droplet 1A is heated by the radiant heat radiated from the wall surface 7a.

In the fourth invention, as shown in FIG. 4, the droplet 1A is heated by radiant heat radiated from a lamp 7a composed of a halogen lamp, an arc lamp or an incandescent lamp.

In the fifth invention, as shown in FIG. 5, the lamp 7a is disposed along the supply path 1B of the droplet 1A. As shown in FIG. 6, the intensity distribution of the radiant heat radiated from the lamp 7a is wide in the direction along the supply path 1B of the droplet 1A and narrow in the direction perpendicular to the supply path 1B of the droplet 1A. Yes.

In the sixth invention, as shown in FIG. 9, the wall surface 7a is heated by resistance heating, and the droplet 1A is heated by the radiant heat radiated from the wall surface 7a. As shown in FIG. 10, the wall surface 7a is heated by induction heating, and the droplet 1A is heated by the radiant heat radiated from the wall surface 7a.

In the seventh invention, as shown in FIG. 8, the wall surface 7a is a wall surface surrounding the supply path 1B of the droplet 1A, and the droplet 1A is heated by the radiant heat radiated from the wall surface 7a. As in FIG. 5, the intensity distribution of the radiant heat radiated from the wall surface 7a is wide in the direction along the supply path 1B of the droplet 1A and narrow in the direction perpendicular to the supply path 1B of the droplet 1A. .

In the eighth invention, as shown in FIG. 11, the heating chamber 7c in which the droplet 1A is heated and the space (vacuum chamber 2) in which EUV light is generated include openings 7d, 7e, 7f through which the droplet 1A passes. Partitioned by partition walls 7g1, 7g2, and 7g3. Therefore, the liquid component of the droplet 1A can be evaporated or sublimated in the heating chamber 7c without increasing the pressure in the vacuum chamber 2.

In the ninth invention, the droplet 1A that is a liquid metal, a metal solution, a metal compound solution, or a colloidal solution containing metal particles or metal compound particles is supplied toward the EUV generation point A.

  In the tenth aspect of the invention, the droplet 1A whose main metal component is tin Sn or lithium Li is supplied toward the EUV generation point A.

  In the eleventh aspect of the invention, a droplet 1A in which the main component of the metal compound is tin oxide SnO2 is supplied toward the EUV generation point A.

In the twelfth invention, the droplet 1A, in which the main component of the solvent is a dispersible liquid or organic solvent, water, liquid nitrogen, or liquid xenon, is supplied toward the EUV generation point A.

The thirteenth invention is a method invention corresponding to the invention of the apparatus of the first invention, and the same effect as the first invention can be obtained.

  Embodiments of an EUV light generation apparatus and method according to the present invention will be described below with reference to the drawings.

(First apparatus configuration example)
FIG. 2 shows a first device configuration example.

The EUV light generation apparatus 10 shown in FIG. 2 is an apparatus that generates the EUV light 5 by setting the target 1 located at the EUV light generation point A to a plasma state and outputs the EUV light 5 to the outside.

The EUV light generation apparatus 10 is an EUV light generation apparatus based on the LPP method used as a light source of the exposure apparatus 20.

That is, a condensing mirror 3 that condenses EUV light is provided inside the vacuum chamber 2 of the EUV light generator 10. The EUV light condensed by the condenser mirror 3 is transmitted to the exposure apparatus 20 outside the vacuum chamber 2. In the exposure apparatus 20, a semiconductor circuit pattern is formed on the semiconductor wafer using the EUV light 5.

  The inside of the vacuum chamber 2 is evacuated by a vacuum pump or the like and is in a vacuum state. The gas in the vacuum chamber 2 is exhausted to the outside by the exhaust device 40. The space where EUV light is generated is in a vacuum state because the EUV light has a short wavelength of 13.5 nm and cannot be efficiently transmitted unless it is in a vacuum.

  The target 1 serving as an EUV light generation source becomes a droplet (droplet) 1A and is supplied to a predetermined EUV light generation point A in the vacuum chamber 2, that is, a condensing point of the laser light L.

The droplet 1A is a liquid metal, a metal solution, a metal compound solution, or a colloidal solution containing metal particles or metal compound particles.

When the target 1 in the droplet 1A is made of metal, the main component of the metal can be, for example, tin Sn or lithium Li.

Moreover, when the target 1 in the droplet 1A is composed of a metal compound, the main component of the metal compound can be, for example, tin oxide SnO2.

The main component of the solvent of the droplet 1A can be, for example, a dispersible liquid or organic solvent, water, liquid nitrogen, or liquid xenon. As the organic solvent, for example, methanol, ethanol, acetone, or a mixed solution thereof can be used.

The following description will be made on the assumption that the droplet 1A is a colloidal solution containing metal particles 1C of tin Sn or metal compound particles 1C ′ of tin oxide SnO2.

In the driver laser device 4 as a laser oscillator, the laser beam L is pulse-oscillated and the laser beam L is emitted. The laser is a CO2 laser. It is also possible to use other lasers, for example Nd: YAG lasers.

The laser light L is condensed at an EUV light generation point A through a condensing optical system 8 constituted by a condensing lens or the like. The laser beam L is irradiated to the target 1 at the timing when the target 1 in the droplet 1A is positioned at the EUV light generation point A. By irradiating the target 1 with the laser beam L, the target 1 is excited into a plasma state and EUV light is generated. That is, the target 1 is brought into a plasma state with the target 1 being a certain space in which the aggregate of the metal particles 1C or the metal compound particles 1C ′ or the metal particles 1C or the metal compound particles 1C ′ are dispersed.

  The generated EUV light 5 diverges in all directions around the plasma. The collector mirror 3 is disposed so as to surround the plasma. The EUV light that diverges in all directions is collected by the collecting mirror 3 and reflects the collected EUV light. The condensing mirror 3 selectively reflects a desired wavelength of 13.5 nm. The EUV light 5 (output EUV light) reflected by the condenser mirror 3 is propagated to the exposure device 20. A broken line in FIG. 2 indicates an optical path of EUV light.

  A part of the droplet 1A, that is, a part of the target 1 is split and scattered by a shock wave at the time of plasma generation and becomes debris. Debris includes charged ions, fast ions, and residues that did not become plasma.

  A collection device 30 is provided in the direction in which the droplet 1A is supplied. The recovery device 30 is configured by, for example, a filter, a vacuum pump, or the like, and recovers debris by trapping the debris or evacuating and discharging it to the outside.

The target supply unit 6 includes a nozzle 6a and the like, and is a device that drops the droplet 1A toward the EUV light generation point A. The target supply means 6 supplies the droplet 1A toward the EUV light generation point A along the supply path 1B.

  The droplet heating means 7 includes a heat source 7a disposed around the supply path 1B of the droplet 1A. The droplet 1A is heated by the radiant heat radiated from the heat source 7a. The heat source 7a is a lamp composed of a halogen lamp, an arc lamp, or an incandescent lamp.

  The droplet heating means 7 is formed around the space 7h through which the droplet 1A passes, that is, the space 7h including the supply path 1B, and supplies power to the cylindrical member 7i provided with the lamp 7a and the lamp 7a. And a power supply device 7j that generates heat from the lamp 7a. When power is supplied to the lamp 7a by the power supply device 7j, the lamp 7a generates heat and radiates radiant heat. Thereby, radiant heat is radiated to the space 7h through which the droplet 1A of the cylindrical member 7i passes, that is, the droplet 1A of the supply path 1B.

  In FIG. 3A, the droplet 1A including the metal particles 1C or the metal compound particles 1C ′ is preliminarily heated by the radiant heat radiated from the heat source 7a of the droplet heating means 7 around the supply path 1B. It is a figure which shows that the metal particle 1C or metal compound particle 1C 'became the state aggregated to the density lower than those solid density. In FIG. 3B, the droplet 1A including the metal particles 1C or the metal compound particles 1C ′ is preliminarily heated by the radiant heat radiated from the heat source 7a of the droplet heating means 7 around the supply path 1B. The metal particles 1C or the metal compound particles 1C ′ are in a state of being dispersed in a certain space where the target 1 can be in a plasma state.

  Hereinafter, the operational effects of the above-described first apparatus configuration example will be described.

  According to the first apparatus configuration example, as shown in FIG. 2, the droplet supply means 6 causes the droplet 1A, which is a colloidal solution containing, for example, metal particles 1C or metal compound particles 1C ′, to enter the supply channel 1B. And supplied toward the EUV light generation point A.

Then, as shown in FIG. 3A, for example, a droplet 1A that is a colloidal solution containing metal particles 1C or metal compound particles 1C ′ is a heat source of the droplet heating means 7 around the supply path 1B. It is preliminarily heated by radiant heat radiated from the lamp 7a. Thereby, all or a part of the solvent in the droplet 1A is removed, and the metal particles 1C or the metal compound particles 1C ′ are aggregated to a density lower than their solid density. Alternatively, as shown in FIG. 3B, the radiant heat radiated from the lamp 7a, which is the heat source of the droplet heating means 7 around the supply path 1B, is the droplet 1A including the metal particles 1C or the metal compound particles 1C ′. Is preliminarily heated. Thereby, all or a part of the solvent in the droplet 1A is removed, and the metal particles 1C or the metal compound particles 1C ′ are dispersed in a certain space where the target 1 can be brought into a plasma state.

In this way, all or a part of the solvent component other than the metal component in the droplet 1A is removed, and the droplet 1A in the aggregated state such as the metal particles 1C or the dispersed state such as the metal particles 1C is the EUV light generation point. A is reached. At the EUV light generation point A, the driver laser light L for plasma generation is irradiated onto the droplet 1A, and EUV light 5 is generated.

According to the first apparatus configuration example, since the solvent component is removed and the target 1A in which the metal particles are aggregated or dispersed is irradiated with the laser light L, the solvent component is removed. The generation efficiency of the EUV light 5 is higher than when the target 1A that is not irradiated with the laser light L is irradiated. That is, if a liquid component other than metal is present in the droplet 1A, the liquid component does not contribute to generation of the EUV light 5 and is scattered or evaporated in the vacuum chamber 2 by irradiation with the laser light L. To do. Such scattered or evaporated matter of the solvent becomes debris and adheres to or damages the surface of the optical device such as the condenser mirror 3. As a result, the reflectance of the EUV light 5 is reduced. Further, the gas generated by the evaporation of the solvent stays in the vicinity of the plasma. The staying gas becomes an EUV light absorber. For this reason, the EUV light that can be effectively used is reduced, and the output of the EUV light 5 is substantially reduced. However, the droplet 1A from which the solvent component has been removed in advance does not cause such a decrease in the output of the EUV light 5.

Further, the replacement frequency of the expensive condenser mirror 3 is reduced. As a result, the operation cost of the EUV light generation apparatus 10 can be reduced and the operating rate can be improved.

In the first apparatus configuration example, the preliminary heating of the droplet 1 before the droplet 1A reaches the EUV light generation point A is not performed by laser light, but from the lamp 7a that is a heat source. Therefore, compared with the case of using a laser, the apparatus cost can be kept low and the energy conversion efficiency becomes very high.

Further, as compared with the case where a laser is used, the entire droplet 1A is heated uniformly, so that the position of the droplet 1A is not shifted due to evaporation or sublimation of the liquid component. Therefore, it is possible to prevent the output energy of the EUV light 5 from being varied and the EUV pulse energy from becoming unstable due to the positional deviation of the droplet 1A at the EUV light generation point A. Thereby, it becomes possible to stably produce semiconductor devices with high quality.

As described above, according to the first apparatus configuration example, the apparatus cost can be kept low, the energy conversion efficiency can be improved, the position shift of the droplet 1A can be eliminated, and the EUV light can be stably generated without energy variation. Output will be obtained.

(Second apparatus configuration example)
Implementations in which the first apparatus configuration example is appropriately modified are also possible.

  FIG. 4 shows a second device configuration example. Components other than the droplet heating means 7 are the same as those in the first apparatus configuration example.

  The droplet heating means 7 of the second apparatus configuration example includes a lamp 7a as a heat source, a spheroid mirror 7k that guides radiant heat radiated from the lamp 7a to the supply path 1B, and supplies power to the lamp 7a. And a power supply device 7j that generates heat.

A lamp 7a is disposed at the first focal point of the spheroid of the spheroid mirror 7k. The supply path 1B is located at the second focal point of the spheroid of the spheroid mirror 7k. The lamp 7a is a lamp having a filament shape close to a point light source. As the lamp 7a, either a halogen lamp, an arc lamp, or an incandescent lamp can be used.

When power is supplied to the lamp 7a by the power supply device 7j, the lamp 7a generates heat and radiates radiant heat. Thereby, the radiant heat radiated by the lamp 7a is reflected by the spheroid mirror 7k and radiated to the droplet 1A of the supply path 1B.

In FIG. 4, the droplet heating means 7 is constituted by a set of heating means of a lamp 7a and a spheroid mirror 7k, but is not limited to one set, but two or more sets of lamps 7a and a spheroid mirror It is also possible to arrange 7k around the supply path 1B. Thereby, the uniformity of the radiant heat intensity on the supply path 1B can be improved.

  Since the operational effects of the second device configuration example are the same as the operational effects of the first device configuration example, the description thereof is omitted.

(Third device configuration example)
FIG. 5A shows a third device configuration example. Components other than the droplet heating means 7 are the same as those in the first apparatus configuration example.

  The droplet heating means 7 of the third device configuration example includes a lamp 7a as a heat source, an elliptical condenser mirror 7l that guides radiant heat radiated from the lamp 7a to the supply path 1B, and supplies power to the lamp 7a. It is comprised with the power supply device 7j which heats 7a.

The lamp 7a is formed in a rod shape. The lamp 7a has a long filament shape. The lamp 7a is disposed along the supply path 1B of the droplet 1A.

The elliptical condensing mirror 7l has a length corresponding to the lamp 7a and is arranged along the supply path 1B in the same manner as the lamp 7a.

FIG. 5B shows an AA cross section of the lamp 7a and the elliptical condenser mirror 71, that is, a cross section perpendicular to the supply path 1B. As shown in FIG. 5B, the elliptical condenser mirror 7l has an elliptical surface, and a lamp 7a is disposed at the first focal point of the elliptical surface. The supply path 1B, that is, the droplet 1A is located at the second focal point of the elliptical surface of the elliptical condenser mirror 7l. As the lamp 7a, either a halogen lamp, an arc lamp, or an incandescent lamp can be used.

6A, 6B, and 6C show intensity distributions of radiant heat radiated from the lamp 7a.

In FIG. 6, the z axis is an axis in the direction of the supply path 1B, and the x axis and the y axis are axes in a direction perpendicular to the supply path 1B.

As shown in FIG. 6, the intensity distribution of the radiant heat radiated from the lamp 7a is wide in the z-axis direction along the supply path 1B of the droplet 1A and is perpendicular to the supply path 1B of the droplet 1A. , Narrow in the y-axis direction.

  The operational effects of the third apparatus configuration example are the same as the operational effects of the first apparatus configuration example, and thus description thereof is omitted.

(Fourth device configuration example)
In the third apparatus configuration example shown in FIG. 5, a pair of lamps 7a and an elliptical condenser mirror 7l are provided on one side of the supply path 1B along the supply path 1B, but along the supply path 1B. Thus, it is possible to provide a pair of lamps 7a and an elliptical condenser mirror 7l on both sides of the supply path 1B.

FIG. 7 is a diagram illustrating a fourth device configuration example, and corresponds to FIG.

FIG. 7 shows a cross section perpendicular to the supply path 1B of the lamp 7a and the elliptical condenser mirror 7l. As shown in FIG. 7, along the supply path 1B, a pair of lamps 7a and an elliptical condenser mirror 71 are provided on both sides of the supply path 1B. The two sets of lamps 7a and the elliptical condensing mirror 7l are arranged to face each other so as to sandwich the supply path 1B.

The elliptical condenser mirror 7l has an elliptical surface, and a lamp 7a is disposed at the first focal point of the elliptical surface. The supply path 1B is positioned at the second focal point of the elliptical surface of the elliptical condenser mirror 7l. As the lamp 7a, either a halogen lamp, an arc lamp, or an incandescent lamp can be used.

Similar to FIG. 6, the intensity distribution of the radiant heat radiated from the lamp 7a is wide in the z-axis direction along the supply path 1B of the droplet 1A, and in the x-axis direction perpendicular to the supply path 1B of the droplet 1A. Narrow in the y-axis direction.

  Since the operational effects of the fourth device configuration example are the same as the operational effects of the first device configuration example, the description thereof is omitted.

  In FIG. 7, two sets of lamps 7a and elliptical condensing mirror 7l are arranged facing each other so as to sandwich supply path 1B. However, the number of lamps 7a is not limited to two and three sets or more. It is also possible to arrange the elliptical condenser mirror 7l around the supply path 1B.

(Fifth device configuration example)
In the above first, second, third, and fourth device configuration examples, the heat source 7a of the droplet heating unit 7 is a lamp, but the heat source 7a of the droplet heating unit 7 is a wall surface. Implementation is also possible.

  FIG. 8 shows a fifth device configuration example. Components other than the droplet heating means 7 are the same as those in the first apparatus configuration example.

  The droplet heating means 7 of the fifth device configuration example includes a wall surface 7a as a heat source, a wall surface heating device 7m for heating the wall surface 7a, and a power source for supplying power to the wall surface heating device 7m to cause the wall surface heating device 7m to generate heat. It is comprised with the apparatus 7n.

As the wall surface heating device 7m, a device for heating the wall surface 7a by resistance heating, a device for heating the wall surface 7a by induction heating, or the like can be used.

The wall surface 7a is a wall surface surrounding the supply path 1B of the droplet 1A, and has a length corresponding to the length of the supply path 1B.

When power is supplied to the wall surface heating device 7m by the power supply device 7n, the wall surface heating device 7m generates heat or emits high frequency to heat the wall surface 7a. For this reason, the wall surface 7a generates heat and radiates radiant heat. As a result, radiant heat is radiated to the droplet 1A of the supply path 1B facing the wall surface 7a. When radiant heat is radiated from the wall surface 7a to the droplet 1A, the droplet 1A is heated. Similar to the radiant heat intensity distribution of the lamp 7a shown in FIG. 6, the intensity distribution of the radiant heat radiated from the wall surface 7a is wide in the direction along the supply path 1B of the droplet 1A, with respect to the supply path 1B of the droplet 1A. Narrow in the vertical direction.

(Sixth device configuration example)
FIG. 9A shows a sixth device configuration example.

FIG. 9A illustrates a specific configuration of the wall surface heating device 7m of the droplet heating means 7 shown in FIG. 8, and the wall surface heating device 7m is configured by a device that heats the wall surface 7a by resistance heating. It shows that.

Components other than the droplet heating means 7 are the same as those in the first apparatus configuration example.

  The droplet heating means 7 of the sixth apparatus configuration example is formed with a cylindrical member 7r formed around the space 7p through which the droplet 1A passes, that is, the space 7p including the supply path 1B, and provided with a resistance heater 7q. A wall surface 7a as a heat source that constitutes the inner surface of the cylindrical member 7r, a resistance heater 7q that heats the wall surface 7a, and a power supply device 7n as a heater power source that supplies power to the resistance heater 7q to generate heat from the resistance heater 7q. It consists of and. FIG. 9B is a perspective view of the cylindrical member 7r.

The wall surface 7a is a wall surface surrounding the supply path 1B of the droplet 1A, and has a length corresponding to the length of the supply path 1B.

When power is supplied to the resistance heater 7q by the power supply device 7n, the resistance heater 7q generates heat and the heat is conducted to the wall surface 7a. For this reason, the wall surface 7a generates heat and radiates radiant heat. As a result, radiation heat is radiated to the droplet 1A of the supply path 1B facing the wall surface 7a, and the droplet 1A is heated. Similar to the radiant heat intensity distribution of the lamp 7a shown in FIG. 6, the intensity distribution of the radiant heat radiated from the wall surface 7a is wide in the direction along the supply path 1B of the droplet 1A, with respect to the supply path 1B of the droplet 1A. Narrow in the vertical direction.

(Seventh device configuration example)
FIG. 10 shows a seventh device configuration example.

FIG. 10 illustrates a specific configuration of the wall surface heating device 7m of the droplet heating means 7 shown in FIG. 8, and that the wall surface heating device 7m is configured by a device that heats the wall surface 7a by induction heating. Show.

Components other than the droplet heating means 7 are the same as those in the first apparatus configuration example.

The droplet heating means 7 of the seventh apparatus configuration example is formed in a cylindrical shape in which a space 7p through which the droplet 1A passes, that is, a space 7p including the supply path 1B, is formed and an induction heating coil 7s is provided. A body 7t, a wall surface 7a constituting the inner surface of the cylindrical conductor 7t, a heating source 7s for heating the wall surface 7a, and a cylindrical conductor by supplying electric power to the induction heating coil 7s. It is comprised with the power supply device 7n as an induction heating RF power supply which heats 7t.
The wall surface 7a is a wall surface surrounding the supply path 1B of the droplet 1A, and has a length corresponding to the length of the supply path 1B.

The cylindrical conductor 7t is desirably a conductor having a high melting point and a relatively high resistance value. As the cylindrical conductor 7t, a tube made of carbon, a tube made of steel, or a tube made of tungsten can be used.

When high frequency power is supplied to the induction heating coil 7s by the power supply device 7n, the cylindrical conductor 7t generates heat and the wall surface 7a generates heat. For this reason, radiant heat is radiated by the heat generated by the wall surface 7a. As a result, radiation heat is radiated to the droplet 1A of the supply path 1B facing the wall surface 7a, and the droplet 1A is heated. Similar to the radiant heat intensity distribution of the lamp 7a shown in FIG. 6, the intensity distribution of the radiant heat radiated from the wall surface 7a is wide in the direction along the supply path 1B of the droplet 1A, with respect to the supply path 1B of the droplet 1A. Narrow in the vertical direction.

(Eighth device configuration example)
FIG. 11 shows an eighth apparatus configuration example.

As shown in FIG. 11, a heating chamber 7 c is provided in the vacuum chamber 2.

The heating chamber 7c is a chamber through which the droplet 1A passes and is heated by the droplet heating means 7.

The heating chamber 7c and the space (vacuum chamber 2) where EUV light is generated are partitioned by partition walls 7g1, 7g2, and 7g3 having openings (apertures) 7d, 7e, and 7f through which the droplet 1A passes. The differential exhaust system 50 adjusts the pressures of the chambers 7c, 7u, 7v and the vacuum chamber 2 partitioned by the partition walls 7g1, 7g2, and 7g3 by differential exhaust. Therefore, the liquid component of the droplet 1A can be evaporated or sublimated in the heating chamber 7c without increasing the pressure in the vacuum chamber 2. In FIG. 11, the exhaust pipe of the differential exhaust exhaust device 50 is coupled only to the heating chamber 7 c, but not limited to this, each chamber 7 c, 7 u, 7 v is connected in parallel from the differential exhaust exhaust device 50. It is also possible to exhaust by connecting a pipe. Further, it is also possible to adjust the exhaust of each chamber 7c, 7u, 7v by an independent differential exhaust exhaust device.

As the droplet heating means 7, those exemplified in the first to seventh apparatus configuration examples can be applied. For example, by causing the lamp to generate heat or heating the wall surface 7a of the heating chamber 7c, the droplet 1A can be heated by radiating radiant heat into the heating chamber 7c.

In FIG. 11, the components other than the droplet heating means 7 are the same as those in the first apparatus configuration example.

In each of the above device configuration examples, an LPP type EUV light generation device has been described. However, the present invention is not only an LPP type EUV light generation device, but also a DPP method in which a target is introduced between both electrodes. The present invention can also be applied to an EUV light generator.

FIG. 1 is an apparatus configuration diagram common to the prior art and the embodiment. FIG. 2 is a diagram showing a first apparatus configuration example. FIGS. 3A and 3B are diagrams for explaining that the state is changed by preheating the droplet. FIG. 4 is a diagram showing a second apparatus configuration example. FIGS. 5A and 5B are views showing a third device configuration example. FIGS. 6A, 6B, and 6C are diagrams showing the intensity distribution of radiant heat in three dimensions. FIG. 7 is a diagram showing a fourth device configuration example. FIG. 8 is a diagram illustrating a fifth apparatus configuration example. FIGS. 9A and 9B are diagrams illustrating a sixth apparatus configuration example. FIG. 10 is a diagram showing a seventh apparatus configuration example. FIG. 11 is a diagram showing an eighth apparatus configuration example.

Explanation of symbols

1 target, 1A droplet, 6 droplet supply means, 7 droplet heating means, 10 EUV generator

Claims (13)

In an EUV light generation apparatus in which EUV light is generated by making a target located at an EUV light generation point into a plasma state,
Droplet supplying means for supplying a droplet containing a metal or a metal compound as a target toward an EUV light generation point along the supply path;
An EUV light generation apparatus comprising: a heat source disposed around a droplet supply path; and a droplet heating unit that heats the droplet by radiant heat radiated from the heat source. The EUV light generation apparatus according to claim 1, wherein the droplet heating means is means for heating the droplet using a heat source as a lamp. The EUV light generation apparatus according to claim 1, wherein the droplet heating means is means for heating the droplet using a heat source as a wall surface. 3. The EUV light generation apparatus according to claim 2, wherein the lamp is a halogen lamp, an arc lamp, or an incandescent lamp. The lamp is arranged along the droplet supply path, and the intensity distribution of the radiant heat radiated from the lamp is wide in the direction along the droplet supply path and narrow in the direction perpendicular to the droplet supply path. The EUV light generation apparatus according to claim 2, wherein The EUV light generation apparatus according to claim 3, wherein the wall surface is heated by resistance heating or induction heating. The wall surface is a wall surface surrounding the droplet supply path, and the intensity distribution of the radiant heat radiated from the wall surface is wide in the direction along the droplet supply path and perpendicular to the droplet supply path. 4. The EUV light generator according to claim 3, wherein the EUV light generator is narrow in the direction. The EUV light generation apparatus according to claim 1, wherein the heating chamber in which the droplet is heated and the space in which the EUV light is generated are partitioned by a partition having an opening through which the droplet passes. The EUV light generation apparatus according to claim 1, wherein the droplet is a liquid metal, a metal solution, a metal compound solution, or a colloidal solution containing metal particles or metal compound particles. The EUV light generation apparatus according to claim 1, wherein the main component of the metal is tin Sn or lithium Li. 2. The EUV light generation apparatus according to claim 1, wherein the main component of the metal compound is tin oxide SnO2. The EUV light generation apparatus according to claim 1, wherein the main component of the solvent of the droplet is a dispersible liquid or organic solvent, water, liquid nitrogen, or liquid xenon. An EUV light generation method in which a target located at an EUV light generation point is brought into a plasma state to generate EUV light,
Supplying a droplet containing a metal or a metal compound as a target toward an EUV light generation point along a supply path;
By radiating heat to the droplet, a part or all of the solvent constituting the droplet is removed, and the metal particles or metal compound particles are aggregated to a density lower than that of the solid metal or solid metal compound Or a step of dispersing the target in a certain space where the target can be in a plasma state;
And a step of bringing the target into a plasma state with a target in a space in which metal particles or an aggregate of metal compound particles or metal particles or metal compound particles are dispersed.
An EUV light generator characterized by comprising:

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