Condenser and device for generating extreme ultraviolet light comprising a condenser

Abstract

A condenser for an extreme ultraviolet (EUV) light generator includes a first mirror in a vessel configured to receive a material for generating EUV light and a laser beam, a second mirror surrounding the first mirror, and a detachable third mirror between the first mirror and the second mirror, the third mirror having an inner diameter not less than an outer diameter of the first mirror and an outer diameter not greater than an inner diameter of the second mirror.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0118840, filed on September 7, 2021, with the Korean Intellectual Property Office (KIPO), the entire contents of which are incorporated herein by reference. Technical Field

[0003] The example embodiments relate to a condenser lens and an apparatus for generating extreme ultraviolet light including the condenser lens. More specifically, the example embodiments relate to a condenser lens configured to reflect extreme ultraviolet light and an apparatus for generating extreme ultraviolet light including the condenser lens. Background Technology

[0004] EUV light generating devices can be used to generate extreme ultraviolet (EUV) light. EUV light generating devices can be classified into discharge-generated plasma (DPP) type devices and laser-generated plasma (LPP) type devices.

[0005] DPP-type devices can generate EUV light from high-density plasma formed by applying a high voltage to a material. LPP-type devices can generate EUV light from high-density plasma formed by applying a laser beam to a material. For example, in an LPP-type device, the material and laser can be introduced into a container, and the EUV light generated in the container can be reflected into the exposure chamber through a condenser mirror. Summary of the Invention

[0006] According to an example embodiment, a condenser lens for generating EUV light can be provided. The condenser lens may include a first mirror, a second mirror, and a third mirror. The first mirror may be mounted at a container configured to receive material and a laser for generating EUV light. The second mirror may be configured to surround the first mirror. The third mirror may have an inner diameter not less than the outer diameter of the first mirror and an outer diameter not greater than the inner diameter of the second mirror. The third mirror may be detachably disposed between the first and second mirrors.

[0007] According to an example embodiment, a condenser lens for generating EUV light can be provided. The condenser lens may include a first mirror, a second mirror, and a third mirror. The first mirror may be mounted at a container configured to receive material and a laser for generating EUV light. The second mirror may be configured to surround the first mirror. The third mirror may have an inner diameter substantially the same as the outer diameter of the first mirror and an outer diameter substantially the same as the inner diameter of the second mirror. The third mirror may be detachably disposed between the first and second mirrors. The combined structure between the first, second, and third mirrors may have a hemispherical shape. A first nozzle for injecting air onto the surface of the first mirror may be formed on the upper portion of the inner surface of the first mirror. The upper end of the inner surface of the third mirror may be disposed below the upper end of the outer surface of the first mirror to expose the upper portion of the outer surface of the first mirror. A second nozzle for injecting air onto the surface of the third mirror may be formed on the upper portion of the outer surface of the first mirror. The upper end of the outer surface of the third mirror may be disposed above the upper end of the inner surface of the second mirror to expose the upper portion of the outer surface of the third mirror. A third nozzle for injecting air onto the surface of the second mirror may be formed on the upper portion of the outer surface of the third mirror.

[0008] According to an example embodiment, an apparatus for generating EUV light can be provided. The apparatus may include a container, a material supplier, a laser irradiator, and a condenser lens. The container may be configured to receive material and a laser for generating EUV light. The material supplier may supply material into the container. The laser irradiator may irradiate the material with a laser to generate EUV light. The condenser lens may be configured to reflect EUV light. The condenser lens may include a first mirror, a second mirror, and a third mirror. The first mirror may be mounted at the container. The second mirror may be configured to surround the first mirror. The third mirror may have an inner diameter not less than the outer diameter of the first mirror and an outer diameter not greater than the inner diameter of the second mirror. The third mirror may be detachably disposed between the first and second mirrors. Attached Figure Description

[0009] The features will become clear to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

[0010] Figure 1 This is a diagram illustrating an apparatus for generating EUV light according to an example embodiment;

[0011] Figure 2 It shows Figure 1 A magnified cross-sectional view of the condenser lens in the device;

[0012] Figure 3 It shows Figure 2 A perspective view of the condenser lens separated from the third mirror;

[0013] Figure 4 It shows Figure 2 A cross-sectional view of the condenser lens in the image;

[0014] Figure 5 It shows Figure 4 A magnified cross-sectional view of the third mirror of the condenser lens; and

[0015] Figure 6 It shows Figure 4 Enlarged cross-sectional view of the fixing part of the condenser lens. Detailed Implementation

[0016] Figure 1 This is a diagram illustrating an apparatus for generating EUV light according to an example embodiment.

[0017] Reference Figure 1 The apparatus for generating EUV light according to the example embodiment may include a container 110, a material supplier 120, a laser irradiator 130, and a condenser lens 200.

[0018] Container 110 may have an internal space capable of generating (e.g., producing) EUV light therein. EUV light can be generated from a plasma with high temperatures by irradiating the material with a laser. Container 110 may include a material that will not be damaged by the plasma, for example, it may be formed of a material that will not be damaged by the plasma.

[0019] Container 110 may have a width that gradually decreases from left to right; for example, container 110 may have an approximately conical cross-section. Container 110 may have an open left surface; for example, the bottom of the conical cross-section may include an opening that extends through it or be completely open. A focusing aperture 112 may be formed on the right surface of container 110; for example, focusing aperture 112 may be located at the apex of the conical cross-section facing the bottom of the conical cross-section. EUV light can pass through focusing aperture 112. An exhaust port 114 may be formed through a side surface of container 110, through which byproducts (generated during EUV light generation) can be discharged. Exhaust port 114 may be connected to a scrubber.

[0020] Material supply 120 may be arranged above container 110. Material supply 120 may vertically supply material into container 110, for example, material supply 120 may supply material droplets one by one into container 110 along a direction perpendicular to a line extending from the bottom to the apex of the conical cross-section. For example, the material may include tin, tin compounds, etc.

[0021] In order to accurately supply material droplets to the laser irradiation point in container 110, the position of material supplier 120 can be controlled by a controller. For example, the controller can precisely move material supplier 120 in the vertical and horizontal directions (e.g., along directions parallel and perpendicular to lines extending from the bottom of the conical section to the apex of the conical section).

[0022] The laser irradiator 130 can be arranged on the left side of the container 110, for example, outside the container 110 and adjacent to the bottom of the conical section. The laser irradiator 130 can irradiate the container 110 with a laser beam through, for example, the center of the left surface of the opening of the container 110. Therefore, the irradiation direction of the laser beam from the laser irradiator 130 can be substantially perpendicular to the supply direction of the material droplets. In other words, the irradiation direction of the laser beam can be along a line from the bottom to the apex of the conical section, while the supply direction of the material droplets can be perpendicular to the irradiation direction. For example, the laser irradiator 130 can include, for example, emitting a carbon dioxide laser.

[0023] In order to accurately irradiate the material supplied (e.g., moved) vertically from the material supplier 120 with a laser beam along the horizontal direction, the position of the laser irradiator 130 can be controlled by a controller. For example, the controller can precisely move the laser irradiator 130 in both the vertical and horizontal directions.

[0024] The condenser lens 200 can be positioned on the left surface of the opening of the container 110; for example, the condenser lens 200 can be positioned at the bottom of the opening of the tapered section of the container 110. For example, as... Figure 1 As shown, a condenser lens 200 can be positioned between the laser irradiator 130 and the container 110. For example, the condenser lens 200 can be bent out of the container 110 toward the laser irradiator 130. The condenser lens 200 can reflect the EUV light generated in the container 110 toward the focusing aperture 112. The EUV light passing through the focusing aperture 112 can continue (e.g., incident) into the exposure chamber. The condenser lens 200 may include, for example, an aperture 202 in the central portion of the condenser lens 200, so that the laser beam from the laser irradiator 130 can enter the container 110 through the aperture 202.

[0025] Figure 2 This is a magnified cross-sectional view of condenser lens 200. Figure 3 This is a perspective view of the separated third mirror of condenser lens 200. Figure 4 yes Figure 2 A cross-sectional view of the condenser lens in the image. Figure 5 This shows an enlarged cross-sectional view of the third mirror of the condenser lens 200, and... Figure 6 This is an enlarged cross-sectional view of the fixing part of the condenser lens 200. Figure 6 yes Figure 4 A magnified cross-sectional view of a portion of the image.

[0026] Reference Figures 2 to 6 The condenser lens 200 may have a hemispherical shape. The inner surface of the condenser lens 200 (i.e. the surface facing the inside of the container 110) may have a hemispherical shape and may correspond to a reflective surface configured to reflect EUV light toward the focusing aperture 112.

[0027] For details, refer to Figure 2 The condenser lens 200 may include a first lens 210, a second lens 220, and a third lens 230. The first lens 210 may have a first diameter. The second lens 220 may have a second diameter longer than the first diameter. The third lens 230 may have a third diameter longer than the first diameter and shorter than the second diameter. The first lens 210, the third lens 230, and the second lens 220 may be stacked sequentially, for example, from smallest to largest. That is, the third lens 230 may be stacked on top of the first lens 210. The second lens 220 may be stacked on top of the third lens 230, for example, the third lens 230 may be located between the first lens 210 and the second lens 220.

[0028] When the first mirror 210, the third mirror 230, and the second mirror 220 are stacked sequentially and combined with each other, the combined structure of the first mirror 210, the third mirror 230, and the second mirror 220 can have a hemispherical shape. For example, refer to Figure 1 , Figure 2 and Figure 4 Each of the first mirror 210, the third mirror 230, and the second mirror 220 can have a curved surface facing the interior of the container 110, and the combined structure of the first mirror 210, the third mirror 230, and the second mirror 220 can have curved surfaces arranged in a hemispherical shape facing the interior of the container 110. As will be explained in detail below, the curved surfaces can be arranged in a hemispherical shape without overlapping each other. For example, as Figure 3 As shown, the third mirror 230 can be the middle part of a hemispherical structure and can be separable from the hemispherical structure, for example, detachable.

[0029] Reference Figure 1 and Figure 3 The first mirror 210 can be disposed at the center portion of the left side of the opening of the container 110, for example, the first mirror 210 can be disposed at the center of the bottom of the opening of the tapered section of the container 110. The aperture 202 through which the laser beam passes can be formed to pass through the center portion of the first mirror 210. Therefore, the first mirror 210 can have an inner surface 211 configured to define the inner diameter of the first mirror 210 (i.e., the diameter of the aperture 202) and an outer surface 212 configured to define the outer diameter of the first mirror 210. Figure 4 ).

[0030] like Figure 4As shown, a first nozzle 213 may be formed at the upper end of the inner surface 211 of the first mirror 210. The first nozzle 213 may be formed in a direction substantially parallel to the surface of the first mirror 210. The first nozzle 213 may inject air onto the surface of the first mirror 210 to remove byproducts from the surface of the first mirror 210; for example, the first nozzle 213 may inject air onto the surface of the first mirror 210 that connects the inner surface 211 and the outer surface 212 and faces the interior of the container 110. A first air source 260 may be connected to the first nozzle 213. Therefore, air may be supplied from the first air source 260 to the first nozzle 213.

[0031] like Figure 4 As further shown, the first mirror 210 may include a plate-shaped main body portion 218. The main body portion 218 may extend from the outer surface 212 of the first mirror 210 along the radial direction of the first mirror 210. The main body portion 218 may be located below the third mirror 230. For example, see reference... Figure 3 and Figure 4 The main body 218 may extend between the first mirror 210 and the second mirror 220, for example, connecting the first mirror 210 and the second mirror 220.

[0032] like Figure 3 and Figure 4 As shown, the second diameter of the second mirror 220 can be longer than the first diameter of the first mirror 210, so the second mirror 220 can be configured to surround, for example, the entire outer periphery of the first mirror 210. Therefore, the second mirror 220 can have an inner surface 222 (i.e., the surface facing the first mirror 210) configured to define the inner diameter of the second mirror 220 and an outer surface configured to define the outer diameter of the second mirror 220.

[0033] For example, such as Figure 3 As shown, the second mirror 220 can be integrally formed with the first mirror 210. For example, the inner surface 222 of the second mirror 220 can be integrally formed with the outer surface 212 of the first mirror 210 via the main body portion 218 (the inner surface 222 of the second mirror 220 can be connected to the outer surface 212 of the first mirror 210 via the main body portion 218). In another example, the second mirror 220 can be a separate portion that is detachably connected to the first mirror 210.

[0034] like Figure 3 and Figure 4 As further shown, the third mirror 230 can be arranged between the first mirror 210 and the second mirror 220. Byproducts dispersed in the container 110 can partially stagnate (e.g., remain stationary) around the third mirror 230. Therefore, the byproducts may primarily contaminate the third mirror 230 rather than the first mirror 210 and the second mirror 220.

[0035] The third mirror 230 may have an inner surface 232 configured to define the inner diameter of the third mirror 230 and an outer surface 234 configured to define the outer diameter of the third mirror 230. The inner diameter of the third mirror 230 may not be smaller than the outer diameter of the first mirror 210; for example, the third mirror 230 may not extend radially beyond the outer surface 212 of the first mirror 210. The outer diameter of the third mirror 230 may not be larger than the inner diameter of the second mirror 220; for example, the third mirror 230 may not extend radially beyond the inner surface 222 of the second mirror 220. Therefore, the third mirror 230 may enter (e.g., be inserted) into the space between the first mirror 210 and the second mirror 220 (e.g., between the outer surface 212 of the first mirror 210 and the inner surface 222 of the second mirror 220) without interfering with the first mirror 210 and the second mirror 220. In other words, the third mirror 230 may not overlap with the surfaces of the first mirror 210 and the second mirror 220 facing the interior of the container 110; for example, it may not cover or interfere with the surfaces of the first mirror 210 and the second mirror 220 facing the interior of the container 110. Therefore, there may be no overlap between the first mirror 210 and the third mirror 230, or between the third mirror 230 and the second mirror 220 along the direction facing the interior of the container 110.

[0036] For example, such as Figure 3 As shown, the third mirror 230 can be removed, for example, transplantable or detachable, along a direction that is vertical (e.g., orthogonal) to the main body 218 extending between the first mirror 210 and the second mirror 220. Since the third mirror 230 can be removed vertically from the condenser lens 200 (e.g., only), a separate cleaning process can be performed on the third mirror 230.

[0037] In an example embodiment, the inner diameter of the third mirror 230 may be substantially the same as the outer diameter of the first mirror 210. Therefore, the inner surface 232 of the third mirror 230 may, for example, directly contact the outer surface 212 of the first mirror 210. A labyrinth seal 216 may be formed on the outer surface 212 of the first mirror 210 that contacts the inner surface 232 of the third mirror 230.

[0038] Reference Figure 5The upper end of the inner surface 232 of the third mirror 230 can be located below, for example, the upper end of the outer surface 212 of the first mirror 210, at a height lower than the upper end of the outer surface 212 of the first mirror 210. In other words, the surface of the first mirror 210 facing the inside of the container 110 can be located at a height higher than the surface of the third mirror 230 facing the inside of the container 110 relative to the bottom of the main body 118. Therefore, the outer surface 212 of the first mirror 210 can extend beyond the surface of the third mirror 230 facing the inside of the container 110 relative to the bottom of the main body 118, for example, above the surface of the third mirror 230 facing the inside of the container 110. Thus, the upper part of the outer surface 212 of the first mirror 210 can be exposed by the inner surface 232 of the third mirror 230, rather than being covered by the inner surface 232 of the third mirror 230.

[0039] like Figure 5 As further shown, a second nozzle 214 may be formed on the upper part of the outer surface 212 of the first mirror 210. The second nozzle 214 may be formed in a direction substantially parallel to the surface of the third mirror 230 facing the interior of the container 110. The second nozzle 214 may inject air onto the surface of the third mirror 230 to remove byproducts from the surface of the third mirror 230. A second air source 262 may be connected to the second nozzle 214. Figure 4 Therefore, air can be supplied from the second air source 262 to the second nozzle 214.

[0040] In an example embodiment, the outer diameter of the third mirror 230 may be substantially the same as the inner diameter of the second mirror 220. Therefore, the outer surface 234 of the third mirror 230 may, for example, directly contact the inner surface 222 of the second mirror 220. A labyrinth seal 238 may be formed on the outer surface 234 of the third mirror 230 that contacts the inner surface 222 of the second mirror 220.

[0041] Reference Figure 5 The upper end of the outer surface 234 of the third mirror 230 can be located above the upper end of the inner surface 222 of the second mirror 220, for example, at a height higher than the upper end of the inner surface 222 of the second mirror 220. In other words, the surface of the third mirror 230 facing the interior of the container 110 can be located at a height higher than the surface of the second mirror 220 facing the interior of the container 110 relative to the bottom of the main body 118. Therefore, the outer surface 234 of the third mirror 230 can extend beyond the surface of the second mirror 220 facing the interior of the container 110 relative to the bottom of the main body 118, for example, above the surface of the second mirror 220 facing the interior of the container 110. Thus, the upper part of the outer surface 234 of the third mirror 230 can be exposed by the inner surface 222 of the second mirror 220, rather than being covered by the inner surface 222 of the second mirror 220.

[0042] A third nozzle 236 may be formed on the upper part of the outer surface 234 of the third mirror 230. The third nozzle 236 may be formed in a direction substantially parallel to the surface of the second mirror 220 facing the interior of the container 110. The third nozzle 236 may inject air onto the surface of the second mirror 220 to remove byproducts from the surface of the second mirror 220. A third air source 264 may be connected to the third nozzle 236. Figure 4 Therefore, air can be supplied from the third air source 264 to the third nozzle 236.

[0043] Controller 270 can independently control the first air source 260, the second air source 262, and the third air source 264. Figure 4 Specifically, controller 270 can independently control the air pressure in the first air source 260, the air pressure in the second air source 262, and the air pressure in the third air source 264. As described above, because the contamination level of the third mirror 230 can be relatively higher than that of the first mirror 210 and the second mirror 220, the air pressure of the air ejected from the second nozzle 214 to clean the third mirror 230 can be higher than the air pressure of the air ejected from the first nozzle 213 and the third nozzle 236 to improve cleaning efficiency. Therefore, controller 270 can provide the second air source 262 with a higher air pressure than the air pressure in the first air source 260 and the third air source 264.

[0044] To secure the third mirror 230 to the main body 218 between the first mirror 210 and the second mirror 220, the third mirror 230 may include a fixing portion 240. The fixing portion 240 may extend from the lower surface of the third mirror 230 toward the main body 218. For example, the fixing portion 240 may include a portion arranged along a circumference of the third mirror 230, or the fixing portion 240 may extend continuously to surround the entire periphery of the first mirror 210. In another example, the fixing portion 240 may include multiple portions arranged along multiple circumferences of the third mirror 230, or the fixing portion 240 may include multiple discrete portions spaced apart from each other circumferentially to surround the first mirror 210.

[0045] In detail, such as Figure 6 As shown, the fixing part 240 may include a downwardly tapering lower end 242. A fixing groove 219 may be formed in the main body 218, so that the tapering lower end 242 of the fixing part 240 can be inserted into the fixing groove 219 in the main body 218. The fixing groove 219 may have a tapering shape corresponding to the tapering lower end 242.

[0046] Furthermore, a magnet 250 may be arranged in the main body 218. The magnet 250 may be configured to use magnetic force to fix the fixing part 240. In order to apply the magnetic force from the magnet 250 to the fixing part 240, the fixing part 240 may include a magnetic material. For example, the magnet 250 may include an electromagnet.

[0047] According to the example embodiment, the condenser lens 200 may include three mirrors, as described above. In other examples, the condenser lens 200 may include two mirrors or at least four mirrors.

[0048] By summarizing and reviewing, byproducts generated during EUV light generation can accumulate in the EUV light generator, for example, stacking on the surface of the condenser lens, thus contaminating it. For instance, byproducts can concentrate in the central portion of the condenser lens, so the contamination level in the central portion can be relatively higher than in other parts of the condenser lens. While the entire condenser lens can be separated from the device to be cleaned, this can be complex and reduce the overall usable operating time of the device.

[0049] Conversely, the example embodiment provides a condenser lens capable of partial cleaning, and an apparatus for generating EUV light including the condenser lens. That is, according to the example embodiment, the condenser lens may include a third lens (which may be primarily contaminated during EUV light generation) detachably disposed between the first and second lenses, allowing cleaning to be performed only on the third lens. Therefore, it may not be necessary to separate the entire condenser lens from the container, thereby increasing the overall available operating time of the EUV light generator.

[0050] Example embodiments have been disclosed herein, and although specific terminology has been used, it is for descriptive purposes only and should be interpreted in a general descriptive sense, not for limiting purposes. In some instances, as will be appreciated by those skilled in the art upon which this application has been filed, features, characteristics, and / or elements described in connection with particular embodiments may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless expressly stated otherwise. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. A condenser lens for an extreme ultraviolet (EUV) light generator, the condenser lens comprising: The first mirror is located in a container configured to receive material and a laser beam for generating EUV light. The second mirror surrounds the first mirror; as well as A detachable third mirror, located between the first and second mirrors, has an inner diameter identical to the outer diameter of the first mirror and an outer diameter identical to the inner diameter of the second mirror. The first mirror includes a fixing groove, and the third mirror includes a fixing portion extending from the lower surface of the third mirror into the fixing groove. The fixing part has a downwardly tapering lower end, and the fixing groove has a tapering shape corresponding to the tapering lower end of the fixing part. The third mirror is configured to move downward from above the first and second mirrors, such that the fixing part is inserted into the fixing groove.

2. The condenser lens according to claim 1, wherein, The combined structure of the first mirror, the second mirror, and the third mirror has a hemispherical shape.

3. The condenser lens according to claim 2, wherein, The inner surface of the third mirror is in direct contact with the outer surface of the first mirror.

4. The condenser lens according to claim 3, wherein, The outer surface of the first mirror and the inner surface of the third mirror have a labyrinth seal.

5. The condenser lens according to claim 2, wherein, The outer surface of the third mirror is in direct contact with the inner surface of the second mirror.

6. The condenser lens according to claim 5, wherein, The outer surface of the third mirror and the inner surface of the second mirror have a labyrinth seal.

7. The condenser lens according to claim 1, wherein, The first mirror includes: A first surface facing the interior of the container; and An inner surface, connected to the first surface, the upper portion of the inner surface including a first nozzle pointing towards the first surface to spray air.

8. The condenser lens according to claim 7, further comprising: A first air source is connected to the first nozzle, and the first air source is configured to supply air to the first nozzle. as well as The controller is configured to control the pressure of the air supplied from the first air source to the first nozzle.

9. The condenser lens according to claim 1, wherein: The upper end of the inner surface of the third mirror is located at a lower height than the upper end of the outer surface of the first mirror, thus exposing the upper part of the outer surface of the first mirror. The second nozzle is located on the exposed upper part of the outer surface of the first mirror, and the second nozzle points towards the surface of the third mirror.

10. The condenser lens according to claim 9, further comprising: A second air source is connected to the second nozzle, and the second air source is configured to supply air to the second nozzle; as well as The controller is configured to control the pressure of the air supplied from the second air source to the second nozzle.

11. The condenser lens according to claim 1, wherein: The upper end of the outer surface of the third mirror is located at a height higher than the upper end of the inner surface of the second mirror, thus exposing the upper part of the outer surface of the third mirror. The third nozzle is located on the exposed upper part of the outer surface of the third mirror, and the third nozzle points towards the surface of the second mirror.

12. The condenser lens according to claim 11, further comprising: A third air source is connected to the third nozzle, and the third air source is configured to supply air to the third nozzle; as well as The controller is configured to control the pressure of the air supplied from the third air source to the third nozzle.

13. The condenser lens according to claim 1, further comprising a magnet in the first lens to fix the fixing part using magnetic force.

14. A condenser lens for an extreme ultraviolet (EUV) light generator, the condenser lens comprising: The first mirror, in a container, is configured to receive material and a laser beam to generate EUV light; The second mirror surrounds the first mirror; as well as A detachable third mirror, located between the first and second mirrors, has an inner diameter identical to the outer diameter of the first mirror and an outer diameter identical to the inner diameter of the second mirror. The combined structure of the first mirror, the second mirror, and the third mirror has a hemispherical shape. The first mirror includes a first nozzle located on the upper part of its inner surface, the first nozzle pointing towards the first mirror. The upper end of the inner surface of the third mirror is located at a lower height than the upper end of the outer surface of the first mirror, thus exposing the upper part of the outer surface of the first mirror. A second nozzle is positioned at the exposed upper part of the outer surface of the first mirror to inject air into the third mirror. The upper end of the outer surface of the third mirror is positioned at a height higher than the upper end of the inner surface of the second mirror, thus exposing the upper part of the outer surface of the third mirror. A third nozzle is positioned at the exposed upper part of the outer surface of the third mirror to spray air into the second mirror. The first mirror includes a fixing groove, and the third mirror includes a fixing portion extending from the lower surface of the third mirror into the fixing groove. The fixing part has a downwardly tapering lower end, and the fixing groove has a tapering shape corresponding to the tapering lower end of the fixing part. The third mirror is configured to move downward from above the first and second mirrors, such that the fixing part is inserted into the fixing groove.

15. The condenser lens according to claim 14, further comprising: A first air source is connected to the first nozzle and configured to supply air to the first nozzle; A second air source is connected to the second nozzle and configured to supply air to the second nozzle; A third air source is connected to the third nozzle and configured to supply air to the third nozzle; as well as The controller is configured to individually control the pressure from the first air source to the third air source to the first nozzle to the third nozzle, respectively.

16. An apparatus for generating extreme ultraviolet (EUV) light, the apparatus comprising: The container is configured to receive material and a laser beam to generate the EUV light; A material supplier is configured to supply the material into the container; A laser irradiator is configured to irradiate the material in the container with the laser beam; as well as A condenser lens, configured to reflect the EUV light, includes: The first mirror is in the container. The second frame surrounds the first frame, and A detachable third mirror, located between the first and second mirrors, has an inner diameter identical to the outer diameter of the first mirror and an outer diameter identical to the inner diameter of the second mirror. The first mirror includes a fixing groove, and the third mirror includes a fixing portion extending from the lower surface of the third mirror into the fixing groove. The fixing part has a downwardly tapering lower end, and the fixing groove has a tapering shape corresponding to the tapering lower end of the fixing part. The third mirror is configured to move downward from above the first and second mirrors, such that the fixing part is inserted into the fixing groove.

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