Patent Description:
X-rays have been conventionally used for medical, industrial, and research applications. In the medical field, X-rays are used for such applications as chest radiography, dental radiography, and computed tomography (CT). In the industrial field, X-rays are used for such applications as non-destructive testing and tomographic non-destructive testing to observe the inside of materials such as structures and welds. In the research field, X-rays are used for such applications as X-ray diffraction to analyze the crystal structure of materials and X-ray spectroscopy (X-ray fluorescence analysis) to analyze the constituent elements of materials.

X-rays can be generated using an X-ray tube, in which a pair of electrodes (anode and cathode) are provided. When a high voltage is applied between the anode and cathode while a cathode filament is being heated by flowing an electric current therethrough, negatively charged thermoelectrons that are generated at the filament collide with a target on the anode surface at high speed, generating X-rays from the target. In X-ray tubes, a technique is also known in which the target on the anode is a liquid metal jet, and this target is irradiated with an electron beam to produce X-rays with high brightness.

Extreme ultraviolet light (hereinafter referred to as EUV light) having a wavelength of <NUM>, which is in the soft X-ray region having a relatively long wavelength among X-rays, has been recently used for exposure light. The base material of a mask for EUV lithography, the mask being provided with fine patterns, is a reflective mirror having a stacked structure, which is provided with a multilayer film (e.g., molybdenum and silicon) for reflecting EUV light on a substrate made of low-thermal-expansion glass. The EUV mask is fabricated on the multilayer film by patterning a material that absorbs radiation having a wavelength of <NUM>.

The size of unacceptable defects in EUV masks is much smaller than that of conventional ArF masks, making its detection difficult. Hence, EUV masks are usually inspected using radiation having a wavelength that matches the wavelength operated on lithography, which is called an actinic inspection. For example, when performed using radiation having a wavelength of <NUM>, the actinic inspection can detect defects with resolution better than l0 nm.

EUV light source apparatuses generally include DPP (Discharge Produced Plasma) light source apparatuses, LDP (Laser Assisted Discharge Produced Plasma) light source apparatuses, and LPP (Laser Produced Plasma) light source apparatuses. The DPP type EUV light source apparatus applies high voltage between electrodes between which discharge gas containing EUV radiation species (plasma raw material in the gas phase) is supplied to generate a high-density high-temperature plasma by the discharge, thus utilizing the extreme ultraviolet light radiated from the plasma.

The LDP light source apparatus is an improved version of the DPP light source apparatus. In the DPP light source apparatus, for example, a liquid high-temperature plasma raw material such as Sn (tin) or Li (lithium) containing EUV radiation species is supplied to the surface of the electrode (discharge electrode) at which the discharge occurs. The material is then irradiated with an energy beam such as a laser beam or an electron beam to vaporize the material, and then a high-temperature plasma is generated by discharge.

The LPP light source apparatus generates plasma by focusing a laser beam on a droplet that has been ejected in a form of a minute liquid droplet, which is the target material for EUV radiation, and by exciting the target material. The droplet is made of materials including tin (Sn) or lithium (Li).

In this way, the DPP method (LDP method) light source apparatus or the LPP method light source apparatus can be used as an EUV light source apparatus that generates EUV light in the soft X-ray region. Meanwhile, since DPP method (LDP method) light source apparatus uses discharge between the electrodes to generate plasma, debris caused by EUV raw materials is eventually likely to generate. In contrast, since the LPP method light source apparatus is designed to set a minute droplet made of tin, which is the EUV raw material, to be a target and focus a laser beam for excitation onto the target, thus making the configuration of the light source apparatus complex. In addition, in the LPP method light source apparatus, it is difficult to stably drop and supply the tin droplets, making the stable generation of EUV light difficult.

Patent Literature <NUM> discloses a method in which a liquid target material for generating X-rays is applied to disk-shaped rotation bodies and the applied liquid material is irradiated with an energy beam (laser beam) to generate X-rays. This method is capable of obtaining high-brightness X-rays with a relatively simple configuration. Applying the method described in Patent Literature <NUM> to an EUV light source apparatus corresponds to the LPP method. However, this method eliminates the need for supplying the EUV raw material in liquid in a form of a droplet. Hence, this method is capable of readily supplying the EUV material, and enables the liquid EUV material to be reliably irradiated with a laser beam, obtaining EUV radiation with a relatively simple configuration. Patent Literature <NUM> discloses an EUV apparatus having the features of the preamble of claim <NUM> and extracting EUV radiation from a side face of the rotation body. Patent Literature <NUM> relates to another EUV device wherein a secondary plasma is generated.

It is important to suppress the effects of debris in the above-mentioned light source apparatuses that emit X-rays, EUV light, or the like.

In view of the above circumstances, it is an object of the present invention to provide a light source apparatus capable of suppressing the effects of debris.

In order to achieve the above-mentioned object, a light source apparatus according to claim <NUM> is devised.

In the light source apparatus, the plate member is configured to be rotatable. The front surface of the plate member is supplied with the plasma raw material and is irradiated with an energy beam. This generates plasma and emits radiation. The plate member is disposed such that the normal axis of the incident area onto which the energy beam is incident is off from the between-axes area, which is located between the incident axis of the energy beam and the emission axis of the radiation. This provides a light source apparatus capable of suppressing the effects of debris associated with the generation of plasma.

The light source apparatus may further include a chamber that accommodates the plate member. In this case, the beam introduction section may include an incident chamber connected to the chamber and an incident aperture that allows the energy beam to enter the chamber from the incident chamber. The plate member may be disposed such that the normal axis is off from the opening of the incident aperture.

The light source apparatus may further include a chamber that accommodates the plate member. In this case, the radiation extraction section may include an emission chamber connected to the chamber and an emission aperture that allows the radiation to enter the emission chamber from the chamber. The plate member may be configured such that the normal axis is off from the opening of the emission aperture.

The light source apparatus may further include a gas supply section that blows gas in a direction from the between-axes area toward the normal axis such that the normal axis is located downstream from the between-axes area.

The chamber may have an inside thereof maintained in a more reduced-pressure atmosphere than that of the incident chamber.

The incident chamber may be supplied with gas to increase its internal pressure.

The chamber may have an inside thereof maintained in a more reduced-pressure atmosphere than that of the emission chamber.

The emission chamber may be supplied with gas to increase its internal pressure.

The between-axes area may include a three-dimensional area constituted by extending a two-dimensional area between the incident axis and the emission axis in a plane including the incident axis and the emission axis, along the normal direction of the plane.

At least either of an angle formed with the incident axis and the normal axis or an angle formed with the emission axis and the normal axis may be configured to be included in a range from <NUM> degrees to <NUM> degrees.

Each of the angle formed with the incident axis and the normal axis and the angle formed with the emission axis and the normal axis may be configured to be included in a range from <NUM> degrees to <NUM> degrees.

The beam introduction section may include an incident protrusion protruding toward the incident area and including the incident aperture at the end of the incident protrusion.

The incident protrusion may have a cone shape with a cross-sectional area that decreases toward the end of the incident protrusion.

The radiation extraction section may include an emission protrusion protruding toward the incident area and including the emission aperture at the end of the protrusion.

The emission protrusion may have a cone shape with a cross-sectional area that decreases toward the end of the emission protrusion.

The light source apparatus may further include a voltage applying section that applies a voltage to the emission protrusion.

The radiation may include X-rays or extreme ultraviolet light.

The light source apparatus may further include a thickness adjustment mechanism that adjusts the thickness of the plasma raw material supplied to the front surface.

As described above, the present invention is capable of suppressing the effects of debris. The effects described herein are not necessarily limiting; however, but they may be any of the effects described in this disclosure.

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

<FIG> is a schematic diagram illustrating a configuration example of a light source apparatus according to an embodiment of the present invention. <FIG> illustrates a schematic cross section of the light source apparatus <NUM> when the light source apparatus <NUM> is cut along the horizontal direction at a predetermined height from its installation surface and viewed from above. In <FIG>, in order to facilitate the understanding of the configuration and operation of the light source apparatus <NUM>, omitted is the illustration of the cross section of portions that does not need to be described on the configuration of the cross section, for example. Hereinafter, the X direction denotes as the left-right direction (the positive side of the X axis is the right side and the negative side is the left side), the Y direction denotes the front-rear direction (the positive side of the Y axis is the front side and the negative side is the rear side), and the Z direction denotes the height direction (the positive side of the Z-axis is the upper side, and the negative side is the lower side). Obviously, the application of the present technology is not limited to the direction in which the light source apparatus <NUM> is used.

The light source apparatus <NUM> is a light source apparatus of the LPP method capable of emitting the radiation R ranging from hard X-rays having a wavelength of <NUM> or less to soft X-rays (including EUV light), for example. Hence, the light source apparatus <NUM> can be used as an X-ray generator or an EUV light source apparatus (EUV radiation generator). Obviously, the present technology can also be applied to light source apparatuses that emit radiation in other wavelength bands.

The light source apparatus <NUM> includes an enclosure <NUM>, a vacuum chamber <NUM>, an energy beam incident chamber <NUM>, a radiation emission chamber <NUM>, a raw material supply mechanism <NUM>, and a controller <NUM>. The enclosure <NUM> is configured such that its external shape is approximately a cube. The enclosure <NUM> includes an emission hole <NUM> formed in the front face of the enclosure <NUM>, an incident hole <NUM> formed in the right side face thereof, two through-holes <NUM> and <NUM> formed in the rear face thereof, and a through-hole <NUM> formed in the left side face thereof. The enclosure <NUM> can be made of any materials; for example, the enclosure is made of metal.

In the present embodiment, the radiation R is set to allow its emission axis EA to pass through the emission hole <NUM> in the front face and extend in the Y-direction (front-rear direction). The radiation R such as X-rays and EUV light is extracted along the emission axis EA and emitted through the emission hole <NUM> toward the front side. In the present embodiment, the energy beam EB is set to allow its incident axis IA to extend from the incident hole <NUM> on the right side face toward the rear side at an oblique angle to the left. As shown in <FIG>, a beam source <NUM> that emits the energy beam EB is disposed outside the enclosure <NUM>. The beam source <NUM> is disposed to allow the energy beam EB to enter the interior of the enclosure <NUM> along the incident axis IA. Examples of the energy beam EB include an electron beam or a laser beam. The beam source <NUM> can be configured to employ any configurations capable of emitting these energy beams EB.

The vacuum chamber <NUM>, the energy beam incident chamber (hereinafter simply referred to as incident chamber) <NUM>, and the radiation emission chamber (hereinafter simply referred to as emission chamber) <NUM> are spatially connected to each other. In other words, the vacuum chamber <NUM> and the incident chamber <NUM> are connected to each other. Similarly, the vacuum chamber <NUM> and the emission chamber <NUM> are connected to each other. In the present embodiment, the vacuum chamber <NUM>, the incident chamber <NUM>, and emission chamber <NUM> are constituted by a chamber body <NUM>, an outer protrusion <NUM> protruding toward the front side from the front face of the chamber body <NUM>, and two inner protrusions <NUM> and <NUM> protruding inward from the inner circumferential face of the chamber body <NUM>. The chamber body <NUM>, the outer protrusion <NUM>, and the two inner protrusions <NUM> and <NUM> are made of metal materials, for example.

The chamber body <NUM> is configured such that its external shape is approximately a rectangular parallelepiped shape, and has its front, rear, left, and right faces that are arranged to face the front, rear, left and right faces of the enclosure <NUM>, respectively. The chamber body <NUM> is disposed such that its right-front corner, which is between the front face and the right side face, is located in the incident axis IA of the energy beam EB.

As shown in <FIG>, an emission hole <NUM> is formed in the front face of the chamber body <NUM>. The emission hole <NUM> is formed along the emission axis EA of the radiation R, and in line with the emission hole <NUM> in the front face of the enclosure <NUM>. The outer protrusion <NUM> is configured to protrude toward the front side from the circumferential edge of the emission hole <NUM> in the chamber body <NUM>. The outer protrusion <NUM> is configured to protrude toward the front side more than the emission hole <NUM> of the enclosure <NUM> with being inscribed in the emission hole <NUM> of the enclosure <NUM>. The inner protrusion <NUM> is configured to protrude inward from the circumferential edge of the emission hole <NUM> inside the chamber body <NUM>. The space surrounded by the outer protrusion <NUM> and the inner protrusion <NUM> serves as the emission chamber <NUM>. The outer protrusion <NUM> and the inner protrusion <NUM> themselves, which are the components constituting the emission chamber <NUM>, can also be referred to as the emission chamber. The outer protrusion <NUM> and the inner protrusion <NUM> may be integrally formed with the chamber body <NUM>, or they may be separately formed and then connected to the chamber body <NUM>.

The emission chamber <NUM> is configured to have a cone shape with its central axis being aligned with the emission axis EA of the radiation R. The emission chamber <NUM> is configured to have a large cross-sectional area at its center portion in the direction of the emission axis EA of the radiation R, and have the cross-sectional area being decreased toward the front and rear ends. In other words, the emission chamber <NUM> is shaped to taper toward the front and rear ends.

An incident window <NUM> is formed in the right-front corner of the chamber body <NUM>. The incident window <NUM> is formed along the incident axis IA of the energy beam EB, and in line with the incident hole <NUM> in the right side face of the enclosure <NUM>. The inner protrusion <NUM> is configured to protrude inside the right-front corner of the chamber body <NUM> along the incident axis IA of the energy beam EB from a position surrounding the incident window <NUM>. In the internal space of the chamber body <NUM>, the space surrounded by the inner protrusion <NUM> serves as the incident chamber <NUM>. The inner protrusion <NUM> and the right-front corner of the chamber body <NUM> themselves, which are the components constituting the incident chamber <NUM>, can also be referred to as the incident chamber. The inner protrusion <NUM> may be integrally formed with the chamber body <NUM>, or it may be separately formed and then connected to the chamber body <NUM>.

The incident chamber <NUM> is configured to have a cone shape with its central axis being aligned with the incident axis IA of the energy beam EB. The incident chamber <NUM> is configured to have a cross-sectional area being decreased toward its end inside the chamber body <NUM> in the direction of the incident axis IA of the energy beam EB. In other words, the incident chamber <NUM> has a tapered shape toward the end thereinside.

In the internal space of the chamber body <NUM>, the space excluding the internal space of the inner protrusion <NUM>, which serves as the emission chamber <NUM>, and the internal space of the inner protrusion <NUM>, which serves as the incident chamber <NUM>, serves as the vacuum chamber <NUM>. The components themselves constituting the vacuum chamber <NUM> can also be referred to as the vacuum chamber. As shown in <FIG>, the chamber body <NUM> has a portion that protrudes through the through-hole <NUM> in the left side face of the enclosure <NUM> to the outside of the enclosure <NUM>, and the portion has a front end connected to an exhaust pump <NUM>. The exhaust pump <NUM> exhausts the inside of the vacuum chamber <NUM> and depressurizes the vacuum chamber <NUM>. This suppresses the attenuation of the radiation R generated in the vacuum chamber <NUM>. The inside of the vacuum chamber <NUM> is not necessarily a vacuum atmosphere, provided that it is a reduced-pressure atmosphere with respect to the incident chamber <NUM> and the emission chamber <NUM>. The inside of the vacuum chamber <NUM> may be supplied with an inert gas. The specific configuration of the exhaust pump <NUM> is not limiting, and any pump such as a vacuum pump can be used.

The raw material supply mechanism <NUM> is a mechanism for generating the plasma P in a plasma generation area <NUM> in the vacuum chamber <NUM> and emitting the radiation R (X-rays, EUV light). The raw material supply mechanism <NUM> includes a disk-shaped rotation body <NUM> for supplying raw material, and a container <NUM> that accommodates the liquid-phase plasma raw material (radiation raw material) <NUM>. The rotation body <NUM> and the container <NUM> are disposed inside the vacuum chamber <NUM>. As shown in <FIG>, the disk-shaped rotation body <NUM> has an incident area <NUM> onto which the energy beam EB is incident. The rotation body <NUM> is disposed in the vacuum chamber <NUM> such that the incident area <NUM> is located at the intersection of the incident axis IA and the emission axis EA. The incident area <NUM> of the rotation body <NUM> is supplied with the plasma raw material <NUM> and irradiated with the energy beam EB incident thereon to generate the plasma P The area (space) where the plasma P is generated in the vacuum chamber <NUM> becomes the plasma generation area <NUM>. Accordingly, the plasma generation area <NUM> is an area corresponding to the position of the incident area <NUM> of the rotation body <NUM>. In addition, the detail on the raw material mechanism <NUM> will be described later.

The controller <NUM> controls the operation of each component provided in the light source apparatus <NUM>. For example, the controller <NUM> controls the operation of the beam source <NUM> and the exhaust pump <NUM>. In addition, the controller <NUM> controls the operation of various motors, plasma raw material circulators, external voltage sources, etc., which will be described later. The controller <NUM> includes computer hardware circuits necessary for computers, such as CPUs and memories (RAM, ROM). A CPU loads a control program stored in a memory into a RAM and executes it to perform various processes. The controller <NUM> may use a programmable logic device (PLD) such as field programmable gate array (FPGA), and other devices such as application specific integrated circuit (ASIC). In <FIG>, the controller <NUM> is schematically illustrated as a functional block; however, the controller <NUM> may be designed in any desired manner including the position in which the controller <NUM> is configured. In the present embodiment, the CPU of the controller <NUM> executes programs according to the present embodiment to execute the plasma generation method and the radiation emission method according to the present embodiment.

Hereinafter, the various chambers and the raw material supply mechanism <NUM>, which constitute the light source apparatus <NUM>, will be described in detail.

The incident chamber <NUM> includes the inner protrusion <NUM> at the right-front corner of the chamber body <NUM>. The incident window <NUM> is provided in the right-front corner of the chamber body <NUM>. The energy beam EB emitted from the beam source <NUM> enter the incident chamber <NUM> through the incident window <NUM> along the incident axis IA. Note that the incident axis IA of the energy beam EB can also be referred to as the optical axis (principal axis) of the energy beam EB entering the incident chamber <NUM>.

The incident window <NUM> is made of a material that is transmissive to the energy beam EB and is designed with a thickness that can withstand a pressure difference between the inside and outside of the incident chamber <NUM>. The incident window <NUM> can be made of a metal film such as titanium or aluminum when the energy beam EB is an electron beam. The incident window <NUM> can be made of glass material (quartz glass) when the energy beam EB is a laser beam. The incident window <NUM> can be made of any other materials that are transmissive to the energy beam EB.

The inner protrusion <NUM> protrudes toward the incident area <NUM> on a front surface 22a of the rotation body <NUM> and is provided with an incident aperture <NUM> at the front end of the protrusion. The incident aperture <NUM> is located in line with the incident window <NUM> along the incident axis IA of the energy beam EB. The incident aperture <NUM> allows the energy beam EB to be incident through the incident chamber <NUM> into the vacuum chamber <NUM>. In other words, the energy beam EB traveling along the incident axis IA through the incident window <NUM> passes through the incident aperture <NUM> and enter the rotation body <NUM> located in the vacuum chamber <NUM>.

The incident chamber <NUM> is provided with a capturing mechanism thereinside to capture the scattered plasma raw material <NUM> and debris. In the example shown in <FIG>, provided is a rotary window <NUM> that is a plate-shaped rotation member for transmitting the energy beam EB and capturing the plasma raw material <NUM> and debris, as the capturing mechanism. The rotary window <NUM> is configured to be disk-shaped, for example. The rotary window <NUM> is provided with a rotation shaft of a motor attached to its center, which is not shown in the figure. The motor rotates the rotation shaft, which in turn rotates the rotary window <NUM>. The motor is driven and controlled by the controller <NUM>. The motor is disposed outside the enclosure <NUM>, and the rotation shaft is connected to the rotary window <NUM> through through-holes that are formed in the enclosure <NUM> and the chamber body <NUM>, which are not shown in the figure. A mechanical seal is used to introduce the rotation shaft into the chamber body <NUM>, allowing the rotary window <NUM> to rotate while maintaining the atmosphere (gas atmosphere as will be described below) in the incident chamber <NUM>. The rotation shaft that rotates the rotary window <NUM> is located off from the incident axis IA of the energy beam EB. This allows the energy beam EB to travel through the beam transmission area of the rotary window <NUM> without being interfered by the rotation shaft of the rotary window <NUM>. Rotating the rotary window <NUM> makes it possible to increase the substantial area of the beam transmission area of the rotary window <NUM>, achieving a longer service life of the rotary window <NUM> and reducing the frequency of replacement of the rotary window <NUM>. Measures to be taken against the scattered plasma raw material <NUM> and debris will be discussed in detail later.

As shown in <FIG>, the chamber body <NUM> is provided with a gas injection channel <NUM> that is connected to the incident chamber <NUM>. Through the gas injection channel <NUM>, gas is supplied to the incident chamber <NUM> from a gas supply system, which is omitted in the figure. The gas supplied is gas that has high transmittance to the energy beam EB, for example, a noble gas including argon (Ar) and helium (He). The gas is supplied to increase the pressure inside the incident chamber <NUM>. In other words, supplying gas from the gas injection channel <NUM> to the incident chamber <NUM> enables the internal pressure of the incident chamber <NUM> to be maintained at a pressure sufficiently higher than the internal pressure of the vacuum chamber <NUM>. The inner protrusion <NUM> has a cone shape having a smaller cross-sectional area toward the side of the protrusion (the side in which the incident aperture <NUM> is formed). The incident aperture <NUM> is provided at the front end of the inner protrusion <NUM>. This configuration is favorable for supplying gas to increase the internal pressure of the incident chamber <NUM>. In addition, the inner protrusion <NUM> configured in a cone shape contributes to reducing the space occupied by the inner protrusion <NUM> in the chamber body <NUM>. This allows for more flexibility in designing the arrangement of other components, thereby downsizing the apparatus.

In the present embodiment, the incident chamber <NUM>, inner protrusion <NUM>, incident aperture <NUM>, and other components constitute the beam introduction section that introduces the energy beam. In the present embodiment, the inner protrusion <NUM> serves as the incident protrusion.

The emission chamber <NUM> has a cone-shape with the emission axis EA as its central axis, and the front end (front end of the outer protrusion <NUM>) of the emission chamber <NUM> is connected to a utilization apparatus such as a mask inspection device. In the example shown in <FIG>, an application chamber <NUM> is connected as a chamber that forms part of the utilization apparatus. The pressure inside the application chamber <NUM> may be atmospheric pressure. The interior of the application chamber <NUM> may be purged with gas (e.g., inert gas) introduced from a gas injection channel <NUM>, if necessary. The gas inside the application chamber <NUM> may be exhausted by an exhaust means, which is omitted in the figure.

As shown in <FIG>, the outer protrusion <NUM> is provided with a gas injection channel <NUM> that is connected to the emission chamber <NUM>. Through the gas injection channel <NUM>, gas is supplied to the emission chamber <NUM> from a gas supply device, which is omitted in the figure. The gas supplied is gas that has high transmittance to the radiation R, for example, a noble gas such as argon and helium. Argon and helium can be used as gas having high transmittance for both the energy beam EB and the radiation R. Hence, the same gas may be supplied to both the incident chamber <NUM> and the emission chamber <NUM>. This case makes it possible to use a gas supply system in common, thus simplifying the apparatus. Obviously, the gas supplied to the incident chamber <NUM> may be different from the gas supplied to the emission chamber <NUM>. The gas is supplied to increase the pressure inside the emission chamber <NUM>. In other words, supplying gas from the gas injection channel <NUM> to the emission chamber <NUM> enables the internal pressure of the emission chamber <NUM> to be maintained at a pressure sufficiently higher than the internal pressure of the vacuum chamber <NUM>.

Inside the emission chamber <NUM>, provided is a collector (focusing mirror) <NUM> that guides and focuses the radiation R entering the emission chamber <NUM> into the utilization apparatus (inside the application chamber <NUM>). In <FIG>, the component of the radiation R that enters the emission chamber <NUM> and is focused is illustrated in hatching. The outer surface of the collector <NUM> is in contact with the inner surface of the emission chamber <NUM> (inner surface of the outer protrusion <NUM>) for the purpose of cooling and alignment. The collector <NUM> may be, for example, a single-shell oblique-incidence reflector mirror. The collector <NUM> is made of a metal member such as aluminum (Al), nickel (Ni), or stainless steel.

The collector <NUM> is optionally provided with a reflective coating on the inner reflective surface thereof. The reflective coating that reflects the radiation R is suitably made of a material such as ruthenium (Ru). Instead of being a structure in which its body is coated with Ru, which is expensive, the collector <NUM> may be configured to have a body made of glass (silicon dioxide: SiO2) and to make its inner surface be polished to form a radiation reflecting surface. Although the collector made of glass has a lower reflectivity than the collector made of metal applied with a Ru coating, the material of the collector made of glass is much less expensive than that of the collector with a Ru coating, thereby enabling the collector <NUM> to be replaced more frequently.

The inner protrusion <NUM>, which constitutes the emission chamber <NUM>, protrudes toward the incident area <NUM> on the front surface 22a of the rotation body <NUM>, and is provided with an emission aperture <NUM> at the front end of the protrusion. The emission aperture <NUM> is located in line with the emission hole <NUM> of the chamber body <NUM> and the emission hole <NUM> of the enclosure <NUM> along the emission axis EA of the radiation R. The emission aperture <NUM> allows the radiation R to enter the emission chamber <NUM> from the vacuum chamber <NUM>. In other words, a portion of the radiation R emitted from the plasma P enters the collector <NUM> through the emission aperture <NUM>. The radiation R that has entered the collector <NUM> is guided and focused by the collector <NUM> in the application chamber <NUM>. Designing the opening area of the emission aperture <NUM> appropriately makes it possible to control the aperture angle of the radiation R entering the collector <NUM>. Note that the emission axis EA of the radiation R can also be referred to as the optical axis (principal axis) of the radiation R introduced into the emission chamber <NUM> from the plasma P.

The inner protrusion <NUM> has a cone shape having a smaller cross-sectional area toward the side of the protrusion (the side in which the emission aperture <NUM> is formed). Hence, the inner protrusion <NUM> can also be referred to as a collector cone. The emission aperture <NUM> is provided at the front end of the inner protrusion <NUM>, which has a cone shape. This configuration is favorable for supplying gas to increase the internal pressure of the emission chamber <NUM>. In addition, the inner protrusion <NUM> configured in a cone shape contributes to reducing the space occupied by the inner protrusion <NUM> in the chamber body <NUM>. This allows for more flexibility in designing the arrangement of other components, thereby downsizing the apparatus.

As shown in <FIG>, a filter film <NUM> is provided between the emission chamber <NUM> and the application chamber <NUM>. The filter film <NUM> serves to physically separate the plasma generation area <NUM> in the vacuum chamber <NUM> from the application chamber <NUM> (physically separate the space), preventing the scattered plasma raw material <NUM> and debris from entering the application chamber <NUM>. This will be described later in detail. The filter film <NUM> is made of a material that transmits the radiation R generated in the plasma generation area <NUM>. When the radiation R is X-rays, the filter film <NUM> is constituted by, for example, a beryllium thin film that has a very high transmittance for X-rays. When the radiation R is EUV light, the filter film <NUM> is made of zirconium (Zr), for example.

Although being supplied with gas, the inside of the emission chamber <NUM> has a reduced-pressure atmosphere because it is spatially connected to the vacuum chamber <NUM>. In contrast, the inside of the application chamber <NUM> may have an atmospheric pressure as described above. In this case, there is a pressure difference between the emission chamber <NUM> and the application chamber <NUM>. Accordingly, the filter film <NUM> has a thickness durable enough to withstand this pressure difference. In other words, the filter film <NUM> is configured to avoid destroying the reduced-pressure atmosphere in the emission chamber <NUM>, which is spatially connected to the vacuum chamber <NUM>.

A shielding member (central occultation) <NUM> is disposed inside the emission chamber <NUM>. The shielding member <NUM> is located in line with the emission hole <NUM> of the chamber body <NUM>, the emission hole <NUM> of the enclosure <NUM>, and the filter film <NUM> along the emission axis EA of the radiation R. Among the radiation R emitted from the plasma P and entering the emission chamber <NUM>, there can be the components of radiation that are not focused by the collector <NUM> and that travel in the emission chamber <NUM>. At least part of this unfocused radiation components spread out while traveling. Typically, such radiation components are unusable with the utilization apparatus and often unnecessary. In the present embodiment, the shielding member <NUM> can block the radiation components that are not focused by the collector <NUM>.

In the present embodiment, the emission chamber <NUM>, the outer protrusion <NUM>, the inner protrusion <NUM>, the emission aperture <NUM>, and other components constitute the radiation extraction section that extracts and emits radiation from the generated plasma. In addition, in the present embodiment, the inner protrusion <NUM> serves as the emission protrusion.

<FIG> is a schematic diagram illustrating a configuration example of the raw material supply mechanism <NUM>. <FIG> illustrates the rotation body <NUM> and the container <NUM> viewed from the direction of arrow A in <FIG>. Accordingly, the front surface 22a of the rotation body <NUM> is illustrated in <FIG>.

As shown in <FIG> and <FIG>, the raw material supply mechanism <NUM> includes the disk-shaped rotation body <NUM>, the container <NUM>, a motor <NUM>, a rotation shaft <NUM>, a skimmer <NUM>, and a plasma raw material circulator <NUM>.

The disk-shaped rotation body <NUM> has the front surface 22a and a back surface 22b, and includes the incident area <NUM> onto which the energy beam EB is incident and that is set at a predetermined position on the front surface 22a. Conversely, of the two main surfaces of the rotation body <NUM>, the main surface where the incident area <NUM> is set for the energy beam EB to be incident onto is the front surface 22a. The opposite main surface is the back surface 22b. The rotation body <NUM> is made of a high-melting-point metal such as tungsten (W), molybdenum (Mo), or tantalum (Ta). The lower side of the rotation body <NUM> is partially immersed in the plasma raw material <NUM> stored in the container <NUM>.

When X-rays are emitted as the radiation R, X-ray raw materials are used as the plasma raw material <NUM>. The X-ray raw material is a metal that is in the form of liquid at room temperature. Examples of the X-ray raw material include gallium (Ga), and gallium alloys such as Galinstan (registered trademark), which is a eutectic alloy of gallium, indium (In), and tin (Sn). When EUV light is emitted as the radiation R, EUV raw materials are used as the plasma raw material <NUM>. Examples of the raw material that emits EUV light include tin (Sn) and lithium (Li) that are in the form of liquid. Since Sn and Li are solid at room temperature, the container <NUM> is provided with a temperature control means, which is omitted from the figure. For example, when the EUV raw material is Sn, the container <NUM> is maintained at a temperature above the melting point of Sn.

The rotation shaft <NUM> of the motor <NUM> is connected to the center of the back surface 22b of the rotation body <NUM>. The controller <NUM> controls the operation of the motor <NUM>, which allows the rotation body <NUM> to rotate via the rotation shaft <NUM>. The rotation shaft <NUM> is disposed to extend in a direction orthogonal to the front surface 22a of the rotation body <NUM>. Hence, the rotation body <NUM> rotates around the direction orthogonal to the front surface 22a. The rotation shaft <NUM> passes through the through-hole <NUM> in the enclosure <NUM> and is introduced into the vacuum chamber <NUM> via a mechanical seal <NUM>. The mechanical seal <NUM> allows the rotation shaft <NUM> to rotate while maintaining a reduced-pressure atmosphere in the vacuum chamber <NUM>.

The rotation body <NUM> rotates around the rotation shaft <NUM> while a part of the lower side of the rotation body <NUM> is immersed in the plasma raw material <NUM> stored in the container <NUM>. As a result, the plasma raw material <NUM> that has spread on the front surface 22a of the rotation body <NUM> due to its wettability with the front surface 22a of the rotation body <NUM> is pulled up from the raw material storage portion of the container <NUM> and is transported. Hence, the motor <NUM> and the rotation shaft <NUM> serve as a raw material supply section that apply the raw material to at least a part of the front surface 22a of the rotation body <NUM>. As shown in <FIG>, in the present embodiment, the incident area <NUM> onto which the energy beam EB is incident is set in the vicinity of the circumferential edge of the front surface 22a of the rotation body <NUM>. The configuration and operation of the raw material supply section (motor <NUM> and rotation axis <NUM>) are appropriately designed to supply this incident area <NUM> with the plasma raw material <NUM>.

A skimmer <NUM> is disposed at a predetermined position on the circumferential edge of the rotation body <NUM> as a layer thickness adjustment section for adjusting the layer thickness of the plasma raw material <NUM> that has been supplied on the front surface 22a of the rotation body <NUM> to a predetermined thickness. The skimmer <NUM> is, for example, a structure having a channel structure, and is positioned with a predetermined gap in a manner that the rotation body <NUM> is sandwiched thereinside. The skimmer <NUM> serves as a scraper to scrape off part of the plasma raw material <NUM> that has been applied to the front surface 22a of the rotation body <NUM>.

The interval between the front surface 22a of the rotation body <NUM> and the skimmer <NUM> corresponds to the layer thickness of the plasma raw material <NUM> in the incident area <NUM> of the front surface 22a of the rotation body <NUM> onto which the energy beam EB is incident. The skimmer <NUM> is disposed at a location such that the layer thickness of the plasma raw material <NUM> in the incident area <NUM> of the front surface 22a of the rotation body <NUM> can be appropriately adjusted to a predetermined thickness. Setting the interval between the front surface 22a of the rotation body <NUM> and the skimmer <NUM> appropriately allows the liquid raw plasma material <NUM> that has been applied to the rotation body <NUM> in the raw material storage portion of the container <NUM> to be adjusted such that the layer thickness on the rotation body <NUM> becomes a predetermined layer thickness when the liquid raw plasma material <NUM> passes through the skimmer <NUM> in response to the rotation of the rotation body <NUM>.

The plasma raw material <NUM> on the rotation body <NUM>, the thickness of which has been adjusted by the skimmer <NUM>, is transported to the incident area <NUM>, onto which the energy beam EB is incident, in response to the rotation of the rotation body <NUM>. In other words, the direction of rotation of the rotation body <NUM> is a direction in which the plasma raw material <NUM> on the rotation body <NUM> passes through the skimmer <NUM> and then transported to the incident area <NUM>. In the incident area <NUM>, the plasma raw material <NUM> on the rotation body <NUM> is irradiated with the energy beam EB to generate the plasma P The skimmer <NUM> makes it possible to nearly uniformly supply the plasma raw material <NUM> to the incident area <NUM>. Stabilizing the thickness of the plasma raw material <NUM> in the incident area <NUM> is capable of stabilizing the intensity of the radiation R emitted from the plasma P In the present embodiment, the skimmer <NUM> provides a thickness adjustment mechanism that adjusts the thickness of the plasma raw material that is supplied to the front surface.

The plasma raw material circulator <NUM> appropriately replenishes the container <NUM> with the plasma raw material <NUM> when the plasma raw material <NUM> is consumed due to the operation of generating the radiation R. The plasma raw material circulator <NUM> also serves as a temperature adjustment mechanism (cooling mechanism) for the plasma raw material <NUM>.

As shown in <FIG>, the plasma raw material circulator <NUM> includes a raw material inlet pipe <NUM>, a raw material outlet pipe <NUM>, a raw material storage tank <NUM>, a raw material drive section (pump) <NUM>, and a temperature adjustment mechanism <NUM>. The raw material storage tank <NUM> stores the plasma raw material <NUM>. The raw material inlet pipe <NUM> and the raw material outlet pipe <NUM> are disposed between the raw material storage tank <NUM> and the container <NUM> to communicate the raw material storage tank <NUM> with the container <NUM>. The raw material drive section <NUM> is disposed in the raw material inlet pipe <NUM>. Driving the raw material drive section <NUM> allows the plasma raw material <NUM> that has been stored in the raw material storage tank <NUM> to flow into the raw material inlet pipe <NUM>, circulating the plasma raw material <NUM> in the circulation system of the raw material storage tank <NUM>, the raw material inlet pipe <NUM>, the container <NUM>, and the raw material outlet pipe <NUM>. Examples of the raw material drive section <NUM> include an electromagnetic pump capable of transporting liquid metal (plasma raw material <NUM>) using magnetic force; however, other types of pumps may also be used.

In the present embodiment, the raw material storage tank <NUM> and the raw material drive section <NUM> are disposed outside the vacuum chamber <NUM> and also outside the enclosure <NUM>. The raw material inlet pipe <NUM> and the raw material outlet pipe <NUM>, which extend from the plasma raw material circulator <NUM> to the container <NUM>, pass through the through-hole <NUM> in the enclosure <NUM>, are introduced into the vacuum chamber <NUM> via a seal member <NUM>, and are connected to the container <NUM>. The seal member <NUM> allows the raw material inlet pipe <NUM> and the raw material outlet pipe <NUM> to penetrate from the outside to the inside of the vacuum chamber <NUM> while maintaining a reduced-pressure atmosphere in the vacuum chamber <NUM>.

The plasma raw material <NUM> that has been applied onto the front surface 22a of the rotation body <NUM> is consumed at the area that is irradiated with the energy beam EB. Hence, in order to stably operate the generation of the radiation R (X-ray or EUV light) for a long period of time, a large volume of the plasma raw material <NUM> needs to be stored in the container <NUM>. Meanwhile, the size of the vacuum chamber <NUM> of the light source apparatus <NUM> provides restrictions on the size of the container <NUM> that can be accommodated inside the vacuum chamber <NUM>, thus there may be many cases in which the container <NUM> fails to store a large volume of the plasma raw material <NUM>. Hence, the raw material storage tank <NUM> capable of storing a large volume of the plasma raw material <NUM> is disposed outside the vacuum chamber <NUM>, and is configured to replenish the raw material storage portion of the container <NUM> with the plasma raw material <NUM> via the raw material inlet pipe <NUM>. This configuration allows the amount of the plasma raw material <NUM> in the raw material storage portion of the container <NUM> to be maintained at a constant level over a long period of time, thus enabling the stable operation of generating the radiation R over a long period of time. In other words, the plasma raw material circulator <NUM> circulates the plasma raw material <NUM> between the raw material storage portion of the container <NUM> and the raw material storage tank <NUM> such that the amount of the plasma raw material <NUM> in the raw material storage portion of the container <NUM> is maintained at a constant level.

When the plasma raw material <NUM> that has been applied onto the front surface 22a of the rotation body <NUM> is irradiated with the energy beam EB, the radiation R is generated from the plasma raw material <NUM> (target), and at the same time, the rotation body <NUM> itself is heated. Whenever this heated rotation body <NUM> passes through the raw material storage portion of the container <NUM> in which the plasma raw material <NUM> is stored, the heat in the heated rotation body <NUM> is transferred to the plasma raw material <NUM> in the container <NUM>. Hence, the temperature of the plasma raw material <NUM> in the container <NUM> gradually varies. When the viscosity of the plasma raw material <NUM> varies with temperature, the temperature variations of the plasma raw material <NUM> cause wettability variations of the rotation body <NUM> with respect to the plasma raw material <NUM>, thereby varying the adhesion state of the plasma raw material <NUM> to the rotation body <NUM>. As a result, the output of the radiation R may also vary.

The plasma raw material circulator <NUM> according to the present embodiment includes the raw material storage tank <NUM> that has a relatively large capacity outside the vacuum chamber <NUM> (outside the enclosure <NUM>). Hence, even if the plasma raw material <NUM> that has varied in temperature in the raw material storage portion of the container <NUM> flows into the raw material storage tank <NUM> via the raw material outlet pipe <NUM>, the temperature of the plasma raw material <NUM> in the raw material storage tank <NUM> does not vary much and remains nearly constant. The plasma raw material <NUM>, the temperature of which is maintained nearly constant, flows into the container <NUM> via the raw material inlet pipe <NUM>. In this way, circulating the plasma raw material <NUM> through the plasma raw material circulator <NUM> enables the temperature of the plasma raw material <NUM> in the container <NUM> to be maintained at a nearly constant level. Therefore, this configuration is also capable of stabilizing the adhesion state of the plasma raw material <NUM> to the rotation body <NUM>, stabilizing the output of the radiation R.

In addition, the temperature of the plasma raw material <NUM> in the raw material storage tank <NUM> may be adjusted by the temperature adjustment mechanism <NUM> that is provided inside the raw material storage tank <NUM>. Since the raw material storage tank <NUM> is disposed outside the vacuum chamber <NUM> (outside the enclosure <NUM>), the temperature adjustment mechanism <NUM> can have a large capacity, which is unaffected by the size of the vacuum chamber <NUM>. This makes it possible to reliably adjust the temperature of the plasma raw material <NUM> to a predetermined temperature in a short time.

In this way, utilizing the plasma raw material circulator <NUM> including the temperature adjustment mechanism <NUM> makes it possible to supply the raw material storage portion of the container <NUM> with the plasma raw material <NUM> while maintaining the temperature of the plasma raw material <NUM> at a constant level. For example, in the case that a liquid metal whose temperature in its liquid state is lower than room temperature is used as the plasma raw material <NUM>, this configuration also makes it possible to supply the container <NUM> with the plasma raw material <NUM> in the liquid phase while maintaining the temperature thereof lower than room temperature. Alternatively, in the case that a liquid metal whose temperature in its liquid state is higher than room temperature is used as the plasma raw material <NUM>, this configuration also makes it possible to supply the container <NUM> with the plasma raw material <NUM> in the liquid phase while maintaining the temperature thereof higher than room temperature.

As shown in <FIG>, in the present embodiment, a radiation diagnosis section <NUM> is provided on the front side of the chamber body <NUM> and in the area spatially connected to the vacuum chamber <NUM>. The radiation diagnosis section <NUM> is disposed at a position onto which the radiation R emitted in a direction different from the emission axis EA is incident. The radiation diagnosis section <NUM> measures the physical state of radiation R and includes a detector that detects the presence or absence of the radiation R and a measurement device that measures the output of the radiation R.

In the present embodiment, the rotation body <NUM> provides a plate member that has a front surface and a back surface, is disposed at a position where the introduced energy beam is incident on the front surface, and rotates around a direction orthogonal to the front surface as its rotation axis direction. The raw material supply mechanism <NUM> provides a raw material supply section that generates plasma by supplying the plasma raw material to the incident area where the energy beam is incident on the front surface thereof. The vacuum chamber <NUM> also serves as a chamber that accommodates the plate member.

The rotation body <NUM> rotates around the rotation shaft <NUM> with the state in which a part of the lower side of the rotation body <NUM> is immersed in the plasma raw material <NUM> stored in the container <NUM>. The plasma raw material <NUM> is pulled up from the raw material storage portion of the container <NUM> in a manner that it spreads over the front surface 22a of the rotation body <NUM> due to its wettability with the front surface 22a of the rotation body <NUM>. The plasma raw material <NUM> is then transported to the incident area <NUM> onto which the energy beam EB is incident, with the plasma raw material <NUM> that has been applied on the front surface 22a of the rotation body <NUM>. As shown in <FIG>, the direction of rotation of the rotation body <NUM> is a direction in which the plasma raw material <NUM> supplied to the front surface 22a of the rotation body <NUM> is pulled up from the raw material storage portion of the container <NUM>, passes through the skimmer <NUM>, and reaches the plasma generation area <NUM> (incident area <NUM>).

The plasma raw material <NUM>, which has passed the skimmer <NUM> and the layer thickness of which on the rotation body <NUM> has been adjusted, reaches the incident area <NUM>. Then the energy beam EB is emitted from the beam source <NUM> along the incident axis IA toward the incident area <NUM>. The energy beam EB passes through the incident hole <NUM>, the incident window <NUM>, the rotary window <NUM>, and the incident aperture <NUM>, and is incident onto the incident area <NUM> on which the plasma raw material <NUM> has been supplied. The energy beam EB incident onto the incident area <NUM> heats and excites the plasma raw material <NUM> present on the incident area <NUM> to generate a high-temperature plasma P. The high-temperature plasma P generated in the plasma generation area <NUM> emits the radiation R having a predetermined wavelength.

The radiation R emitted from the high-temperature plasma P travels in various directions. Of the radiation R, the radiation R incident into the emission chamber <NUM> passes through the emission chamber <NUM> and is guided to the utilization apparatus (application chamber <NUM>) such as a mask inspection apparatus. In other words, of the radiation R emitted from the high-temperature plasma P the component that enters the emission chamber <NUM> is extracted to the outside along the emission axis EA.

In the process of supplying plasma raw material <NUM>, the rotation of the rotation body <NUM> often causes the plasma raw material <NUM> adhering to the front surface 22a of the rotation body <NUM> to be scattered by a centrifugal force. In the process of generating plasma P when the plasma raw material <NUM> applied on the rotation body <NUM> is irradiated with the energy beam EB, a part of the plasma raw material <NUM> vaporizes. At that time, a part of the plasma raw material <NUM> (particles of the plasma raw material <NUM>) is released as debris. For example, ions, neutral particles, electrons, or the like are released as debris together with the radiation R. The generation of the plasma P may also involve the sputtering of the rotation body <NUM>, thus releasing material particles of the rotation body <NUM> as debris.

The light source apparatus <NUM> according to the present embodiment employs technology that is capable of suppressing the effects of the scattered plasma raw material <NUM> and debris generated by the radiation of the energy beam EB. This point will be described below.

When the scattered plasma raw material <NUM> or debris enters the incident chamber <NUM> through the incident aperture <NUM>, the plasma raw material <NUM> or debris may adhere to the incident window <NUM>. In this case, when the energy beam EB is a laser beam, for example, the intensity of the laser beam is reduced by the plasma raw material <NUM> and debris adhering to the injection window <NUM>. As a result, the intensity of the radiation R extracted from the plasma P may be reduced.

In the light source apparatus <NUM> according to the present embodiment, the inside of the vacuum chamber <NUM> is maintained in a more reduced-pressure atmosphere than that of the incident chamber <NUM>. Hence, gas supplied from the gas injection channel <NUM> into the incident chamber <NUM> flows from the incident aperture <NUM> toward the vacuum chamber <NUM>. This prevents the scattered plasma raw material <NUM> and debris from entering the incident chamber <NUM> through the incident aperture <NUM>. The inner protrusion <NUM>, which constitutes the incident chamber <NUM>, has a cone-shape and is provided with the incident aperture <NUM> at its end. Hence, supplying gas from the gas injection channel <NUM> into the incident chamber <NUM> enables the internal pressure of the incident chamber <NUM> to be maintained at a pressure sufficiently higher than the internal pressure of the vacuum chamber <NUM>. This makes it more difficult for the plasma raw material <NUM> and debris to enter the injection chamber <NUM> from the incident aperture <NUM>. Furthermore, the formation of the incident aperture <NUM> itself is advantageous in suppressing the entry of the plasma raw material <NUM> and debris into the incident chamber <NUM>.

The rotary window <NUM> is also disposed in the incident chamber <NUM>. This makes it possible to sufficiently suppress the adhesion of the plasma raw material <NUM> and debris to the incident window <NUM>. Suppressing the entry of the plasma raw material <NUM> and debris into the incident chamber <NUM> leads to extending the lifetime of the rotary window <NUM> and reducing the replacement frequency of the rotary window <NUM>.

The vacuum chamber <NUM> has an inside thereof maintained in a more reduced-pressure atmosphere than that of the emission chamber <NUM>. Hence, gas supplied from the gas injection channel <NUM> into the emission chamber <NUM> flows from the emission aperture <NUM> toward the vacuum chamber <NUM>. This prevents the scattered plasma raw material <NUM> and debris from entering the emission chamber <NUM> through the emission aperture <NUM>. The outer protrusion <NUM> and the inner protrusion <NUM>, which constitute the emission chamber <NUM>, each have a cone-shape, and is provided with the emission aperture <NUM> at their ends thereinside. Hence, supplying gas from the gas injection channel <NUM> into the emission chamber <NUM> enables the internal pressure of the emission chamber <NUM> to be maintained at a pressure sufficiently higher than the internal pressure of the vacuum chamber <NUM>. This makes it more difficult for the plasma raw material <NUM> and debris to enter the emission chamber <NUM> from the emission aperture <NUM>. Furthermore, the formation of the emission aperture <NUM> itself is advantageous in suppressing the entry of the plasma raw material <NUM> and debris into the emission chamber <NUM>. The formation of the inner protrusion <NUM> also enables the emission aperture <NUM> to be disposed close to the plasma P that is to be generated. This leads to reducing the opening area of the emission aperture <NUM> for capturing the necessary radiation R. Therefore, this is advantageous to suppress the entry of the plasma raw material <NUM> and debris into the emission chamber <NUM>.

When the radiation R is EUV light and the plasma raw material is Sn, for example, the most of the scattered plasma material <NUM> and debris are Sn. Since Sn has a melting point of approximately <NUM>, it may solidify and deposit when it reaches the outer surface or inner surface of the inner protrusion <NUM>. As the deposition progresses, the emission aperture <NUM> may become blocked by the deposited Sn. To prevent such problems, the inner protrusion <NUM> may be heated and maintained above the melting point of the plasma raw material <NUM> by heating means or temperature control means, which are omitted in the figure. This prevents the blockage of the emission aperture <NUM>.

As shown in <FIG>, an external voltage source <NUM> may be provided to apply a positive or negative voltage to the inner protrusion <NUM>. Applying a voltage to the inner protrusion <NUM> generates an electric field, which in turn can repel ionic debris from the inner protrusion <NUM> or divert the traveling direction of the debris away from the direction of entering the emission chamber <NUM>. In this case, the inner protrusion <NUM> is electrically insulated from other components such as the vacuum chamber <NUM> by an insulator made of ceramic material or the like, which is not shown. The operation of the external voltage source <NUM> is controlled by the controller <NUM>. In the present embodiment, the external voltage source <NUM> provides the voltage applying section that applies voltage to the emission protrusion.

The filter film <NUM> is provided at the front end of the emission chamber <NUM>. The filter film <NUM> can block the scattered plasma raw material <NUM> and debris from entering the application chamber <NUM>. Accumulating the plasma raw material <NUM> and debris on the surface of the filter film <NUM> (the front surface on the emission chamber <NUM> side) gradually decreases the transmittance of radiation R. The filter film <NUM> may be configured to be movable including rotatable such that an area where no debris and other materials are deposited is exposed on the emission chamber <NUM> side when, for example, debris and other materials are deposited on the filter film <NUM> to some extent. The filter film <NUM> may be configured to be interchangeable. Adopting such a configuration can suppress the effects of the scattered plasma raw material <NUM> and debris.

The shielding member <NUM> is disposed in the emission chamber <NUM>. The shielding member <NUM> can prevent debris and other materials traveling along the emission axis EA or its vicinity from reaching the filter film <NUM>. In particular, part of the debris moves at a relatively high speed, potentially damaging the filter film <NUM> when it directly collides with the filter film <NUM>. In the present embodiment, the shielding member <NUM> can prevent debris and other material from colliding with the filter film <NUM>, thereby preventing damage to the filter film <NUM>. Therefore, this configuration is capable of extending the service life of the filter film <NUM>.

<FIG> is a schematic diagram illustrating another configuration example of a container applicable to the light source apparatus <NUM>. In the example shown in <FIG>, the container <NUM> is configured as a cover structure, which can enclose nearly the entire rotation body <NUM>. The container <NUM> is provided with an opening <NUM> at a position corresponding to the incident area <NUM> set on the front surface 22a of the rotation body <NUM>. The energy beam EB is incident onto the incident area <NUM> through the opening <NUM> to generate the plasma P. In addition, the radiation R is extracted from the plasma P through the opening <NUM> and is emitted through the emission chamber <NUM>. Configuring the container <NUM> as a cover structure allows the plasma raw material <NUM> scattered from the rotation body <NUM> to adhere to the inner walls of the container <NUM>, except for the opening <NUM> of the container <NUM>. The plasma raw material <NUM> that has adhered to the inner walls moves to the raw material storage portion at the bottom of the container <NUM>. Hence, the plasma raw material <NUM> hardly disperses into the space inside the vacuum chamber <NUM>, which is the space outside the container <NUM>. Therefore, this configuration is capable of sufficiently preventing the scattered plasma raw material <NUM> from adhering to the inner walls of the vacuum chamber <NUM>.

In the light source apparatus <NUM>, a new technology has been adopted for the arrangement configuration of the rotation body <NUM> to address debris. <FIG> are schematic diagrams to describe the arrangement configuration of the rotation body <NUM>.

In the light source apparatus <NUM>, the arrangement configuration of the rotation body <NUM> is suitably determined based on the mutual positional relationship among the incident axis IA of the energy beam EB entering the incident area <NUM> of the rotation body <NUM>, the emission axis EA of the radiation R extracted from the plasma P, and a normal axis NA in the incident area <NUM> of the front surface 22a of the rotation body <NUM>. The normal axis NA is an axis extending along a normal direction from the point at which the energy beam EB in the incident area <NUM> is incident.

As shown in <FIG>, the rotation body <NUM> is disposed such that the incident axis IA, the emission axis EA, and the normal axis NA are all different from each other in the light source apparatus <NUM>. In addition, the rotation body <NUM> is disposed such that the normal axis NA in the incident area <NUM> of the front surface 22a is off from a between-axes area <NUM> configured between the incident axis IA of the energy beam EB entering the incident area <NUM> and the emission axis EA of the radiation R extracted from the plasma P In other words, the rotation body <NUM> is disposed such that the normal axis NA does not pass through the between-axes area <NUM> between the incident axis IA and the emission axis EA.

When the plasma raw material <NUM> is supplied on a flat surface and irradiated with the energy beam EB, the debris released in response to the vaporization of the plasma raw material <NUM> is released most along the normal direction of the area onto which the energy beam EB is incident. In other words, a large amount of debris is released along the normal axis NA, which extends along the normal direction thereof. In the light source apparatus <NUM> according to the present embodiment, the normal axis NA is located differently from each of the incident axis IA and the emission axis EA. This allows each of the incident aperture <NUM> and the emission aperture <NUM> to be disposed at a location off from a direction from which much of the debris is released with the generation of the plasma P. Therefore, this configuration is capable of suppressing the debris from entering the incident chamber <NUM> and the emission chamber <NUM>.

Moreover, the rotation body <NUM> is located such that the normal axis NA is off from the opening of the incident aperture <NUM>. This makes it possible to further suppress the entry of debris into the incident chamber <NUM>. Similarly, the rotation body <NUM> is located such that the normal axis NA is off from the opening of the emission aperture <NUM>. This makes it possible to further suppress the entry of debris into the emission chamber <NUM>. As shown in <FIG>, in the present embodiment, the normal axis NA is also configured to be off from the opening of the incident aperture <NUM> and the opening of the emission aperture <NUM>. Therefore, this configuration is capable of sufficiently suppress the entry of debris into the incident chamber <NUM> and the emission chamber <NUM>.

As shown in <FIG> and <FIG>, the present embodiment is provided with a gas nozzle <NUM> at the rear side of the incident chamber <NUM>, extending in the left-right direction. The gas nozzle <NUM> is disposed in the right side face of the chamber body <NUM> via a seal member or the like. The gas nozzle <NUM> is connected to a gas supply device, which is omitted in the figure, and supplies gas to the chamber body <NUM>.

In the example shown in <FIG> and <FIG>, the normal axis NA in the incident area <NUM> of the rotation body <NUM> is located at a position of the left side off from the between-axes area <NUM> between the incident axis IA and the emission axis EA when the light source apparatus <NUM> is viewed from above. Then, gas is blown by the gas nozzle <NUM> from the right side of the between-axes area <NUM> toward the left side thereof along the left-right direction. In other words, the gas is blown in a direction that traverses the incident axis lA, the emission axis EA, and the normal axis NA; it is a direction that finally reaches the normal axis NA. This makes it possible to move the debris, which is emitted most along the normal axis NA in the incident area <NUM>, in a direction away from the incident axis IA and the emission axis EA. This configuration is capable of further suppressing the entry of debris into the incident chamber <NUM> and emission chamber <NUM>. Increasing the gas velocity can also increase the effectiveness of suppressing the entry of debris into the incident chamber <NUM> and the emission chamber <NUM>.

In this way, the gas is blown in a direction from the between-axes area <NUM> toward the normal axis NA such that the normal axis NA is located downstream from the between-axes area <NUM>. This makes it possible to sufficiently suppress the entry of debris released with the generation of plasma P into the incident chamber <NUM> and the emission chamber <NUM>. Examples of the gas include noble gases such as argon and helium. The same type of gas supplied to the inside of the incident chamber <NUM> and the emission chamber <NUM> can also be used, for example.

<FIG> are schematic diagrams that describes the between-axes area <NUM> in detail. In the light source apparatus <NUM>, the incident axis IA of the energy beam EB and the emission axis EA of the radiation R are set in a three-dimensional space. As illustrated in <FIG>, a plane <NUM> including the incident axis IA and the emission axis EA is assumed. In the example illustrated in <FIG>, the plane <NUM> is a plane that is not parallel to any of the XY plane, the YZ plane, and ZX plane. Specifically, it is a plane whose front side is inclined to be lower (-Z direction) with respect to the XY plane. Obviously, the embodiments are not limited to such a plane. As shown in <FIG>, a two-dimensional area <NUM> between the incident axis IA and the emitting axis EA on the plane <NUM> including the incident axis IA and the emitting axis EA is moved along the normal direction of the plane <NUM>. The between-axes area <NUM> can define a three-dimensional area constituted by extending the two-dimensional area <NUM> to the upper side and the lower side along the normal direction to the plane <NUM>. The rotation body <NUM> is located at a position such that the normal axis NA in the incident area <NUM> (incident point) is off from the between-axes area <NUM>. In addition, the gas is blown in a direction from the between-axes area <NUM> toward the normal axis NA such that the normal axis NA is downstream from the between-axes area <NUM> when the gas is blown. Satisfying this condition allows the direction in which the gas is blown to be set to any direction. For example, the gas may be blown from an oblique direction of intersecting with the two-dimensional area <NUM>.

In the example shown in <FIG>, the two-dimensional area <NUM> is defined as a triangular area connecting the position of the incident aperture <NUM> in the incident axis lA, the position of the emission aperture <NUM> in the emission axis EA, and the incident area <NUM>. Obviously, the examples are not limited to this; the two-dimensional area <NUM> may be defined using another point in the incident axis IA and another point in the emission axis EA. The two-dimensional area <NUM> may also be defined in a manner that it includes the directions of extending each of the incident axis IA and the emission axis EA without defining points in the incident axis IA and the emission axis EA. In this case, the two-dimensional area <NUM> is not a triangular shape, but a two-dimensional area extending in the direction of extending each of the incident axis IA and the emission axis EA.

Making the angle between the incident axis IA and the normal axis NA of the energy beam EB large is capable of suppressing the debris released the most along the normal axis NA from entering the incident chamber <NUM>. Similarly, making the angle between the emission axis EA of radiation R and the normal axis NA large is capable of suppressing the debris released the most along the normal axis NA from entering the incident chamber <NUM>. The angle between the incident axis IA and the normal axis NA can be defined, for example, by an intersection angle in the plane including the incident axis IA and the normal axis NA. Similarly, the angle between the emission axis EA and the normal axis NA can be defined, for example, by an intersection angle in the plane including the emission axis EA and the normal axis NA.

For example, the light source apparatus <NUM> is configured such that at least either the angle between the incident axis IA and the normal axis NA or the angle between the emission axis EA and the normal axis NA is included in a range of <NUM> degrees to <NUM> degrees. This makes it possible to suppress the effects of debris. The light source apparatus <NUM> may also be configured such that each of the angle between the incident axis IA and the normal axis NA and the angle between the emission axis EA and the normal axis NA is included in a range from <NUM> to <NUM> degrees. This case also makes it possible to suppress the effects of debris.

As shown in <FIG>, it is also possible to swap the arrangement of the incident chamber <NUM> and that of the emission chamber <NUM>. In the configuration example shown in <FIG>, the incident axis IA is located farther from the normal axis NA than the emission axis EA. Hence, the configuration example shown in <FIG> is capable of further suppressing debris from entering the incident chamber <NUM> than the emission chamber <NUM>. In the configuration example shown in <FIG>, the emission axis EA is located farther from the normal axis NA than the incident axis IA. Hence, the configuration example shown in <FIG> is capable of suppressing debris from entering the emission chamber <NUM> than the incident chamber <NUM>. In this way, of the incident chamber <NUM> and emission chamber <NUM>, it is possible to design a configuration in which the chamber that is desired to suppress the entry of debris is away from the normal axis NA. This configuration is capable of sufficiently suppressing the effects of debris.

In the light source apparatus <NUM> according to the present embodiment, the front surface 22a of the rotation body <NUM>, which is configured to be rotatable, is supplied with the plasma raw material <NUM>, and irradiated with the energy beam EB. This generates the plasma P and emits the radiation R. The rotation body <NUM> is disposed such that the normal axis NA in the incident area <NUM> where the energy beam EB enter is off from the between-axes area <NUM> between the incident axis IA of the energy beam EB and the emission axis EA of the radiation R. This makes it possible to suppress the effects of debris associated with the generation of plasma P.

In the light source apparatus <NUM>, the incident area <NUM> onto which the energy beam EB is incident is set when one of the two main surfaces 22a of the plate-shaped rotation body <NUM> is considered to be the front surface 22a. This makes the design of apparatus easier compared to the case where the energy beam EB is incident onto the end (side) face of the rotation body <NUM>, for example, simplifying the apparatus. Moreover, this can improve the degree of freedom in, for example, designing the arrangement of each component. When the plasma raw material (radiation material) supplied to the rotation body <NUM> is liquid, depending on the rotation speed of the rotation body <NUM>, the plasma raw material may detach from the end face of the rotation body <NUM> and scatter as droplets. In other words, the unstable state of the plasma raw material supplied to the end face (side face) of the rotation body <NUM> highly causes the shape of the plasma raw material (thickness of the plasma raw material) in the area irradiated with the energy beam EB on the end face to be unstable, leading to the unstable radiation intensity emitted from the plasma. Hence, it is preferable to irradiate the energy beam EB on the front surface 22a of the rotation body <NUM> rather than on the end face (side face) thereof.

The present invention is not limited to the embodiments described above, and can adopt various other embodiments.

The light source apparatus, the rotation body, the various chambers, the raw material supply mechanism, and other configurations described with reference to the drawings are merely one embodiment and may be arbitrarily modified to the extent not to depart from the intent of the present technology. In other words, any other configurations may be adopted to implement this technology.

In the present disclosure, words such as "about", "nearly", and "approximately" are suitably used to readily understand the explanation. On the other hand, there is no clear difference between the cases in which these words "about", "nearly", and "approximately" are used and the cases in which they are not used. In other words, in the present disclosure, concepts that define shape, size, position relationship, and state, such as "center", "middle", "uniform", "equal", "same", "orthogonal", "parallel", "symmetrical", "extending", "axial direction", "cylindrical shape", "cylindrical hollow shape", "ring shape", and "annular shape", are concepts including "substantially center", "substantially middle", "substantially uniform", "substantially equal", "substantially same", "substantially orthogonal", "substantially parallel", "substantially symmetrical", "substantially extending", "substantially axial direction", "substantially cylindrical shape", "substantially cylindrical hollow shape", "substantially ring shape", and "substantially annular shape". The concepts also include concepts having states in a predetermined range (e.g., ±<NUM>% range) with respect to, for example, "exactly center", "exactly middle", "exactly uniform", "exactly equal", "exactly same", "exactly orthogonal", "exactly parallel", "exactly symmetrical", "exactly extending", "exactly axial direction", "exactly cylindrical shape", "exactly cylindrical hollow shape", "exactly ring shape", "exactly annular shape", and the like. Hence, even when the words such as "about", "nearly", and "approximately" are not added, the concepts may include those that are expressed by adding "about", "nearly", "approximately", and the like. Conversely, states expressed by adding "about", "nearly", "approximately", and the like do not necessarily exclude their exact states.

In the present disclosure, expressions using the term "than" such as "greater than A" and "less than A" are expressions that comprehensively include concepts that include the case that is equal to A and concepts that do not include the case that is equal to A. For example, "greater than A" is not limited to the case where it does not include "equal to A"; however, it also includes "equal to or greater than A". Also, "less than A" is not limited to "less than A"; it also includes "equal to or less than A". Upon the implementation of the present technology, specific settings and other settings are suitably adopted from the concepts that are included in "greater than A" and "less than A" to achieve the effects described above.

Among the characteristic portions according to the present technology described above, it is also possible to combine at least two of the characteristic portions. In other words, the various characteristic portions described in each embodiment may be optionally combined without being restricted to the embodiments. The various effects described above are merely examples and are not limitative; other effects may also be achieved.

Claim 1:
A light source apparatus (<NUM>) comprising:
a beam introduction section that introduces an energy beam (EB);
a plate member having a front surface (22a) and a back surface, being the main surfaces of a rotation body (<NUM>) and disposed at a location where the introduced energy beam (EB) is incident, and being rotatable around a direction orthogonal to the front surface (22a) as its rotation axis direction;
a raw material supply section that supplies plasma raw material (<NUM>) to an incident area (<NUM>) onto which the energy beam (EB) is incident to generate plasma; and
a radiation extraction section that extracts and emits radiation (R) from the plasma generated by the energy beam (EB),
characterized in that
the plate member is disposed such that the introduced energy beam (EB) is incident onto the front surface (22a) and a normal axis (NA) of the incident area (<NUM>) in the front surface (22a) is off from a between-axes area (<NUM>) configured between an incident axis (lA) of the energy beam incident onto the incident area (<NUM>) and an emission axis (EA) of the radiation extracted from the plasma generated in a plasma generation area (<NUM>) corresponding to the position of the incident area (<NUM>) of the rotation body (<NUM>).