Patent Publication Number: US-9429847-B2

Title: Extreme ultraviolet light source apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Continuation of U.S. Ser. No. 14/707,990, filed May 8, 2015, which is a Continuation of U.S. Ser. No. 12/543,582, filed Aug. 19, 2009, claims priority from Japanese Patent Application No. 2008-220892, filed Aug. 29, 2008, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an extreme ultraviolet (EUV) light source apparatus to be used as a light source of exposure equipment. 
     2. Description of a Related Art 
     In recent years, as semiconductor processes become finer, photolithography has been making rapid progress toward finer fabrication. In the next generation, microfabrication at 70 nm to 45 nm, further, microfabrication at 32 nm and beyond will be required. Accordingly, in order to fulfill the requirement for microfabrication at 32 mm and beyond, for example, exposure equipment is expected to be developed by combining an EUV light source for generating EUV light having a wavelength of about 13 nm and reduced projection reflective optics. 
     As the EUV light source, there are three kinds of light sources, which include an LPP (laser produced plasma) light source using plasma generated by applying a laser beam to a target (hereinafter, also referred to as “LPP type EUV light source apparatus”), a DPP (discharge produced plasma) light source using plasma generated by discharge, and an SR (synchrotron radiation) light source using orbital radiation. Among them, the LPP light source has advantages that extremely high intensity close to black body radiation can be obtained because plasma density can be considerably made larger, that the light emission of only the necessary waveband can be performed by selecting the target material, and that an extremely large collection solid angle of 2π steradian can be ensured because it is a point light source having substantially isotropic angle distribution and there is no structure such as electrodes surrounding the light source. Therefore, the LPP light source is considered to be predominant as a light source for EUV lithography, which requires power of more than several tens of watts. 
     In the LPP type EUV light source apparatus, EUV light is generated on the following principle. That is, by supplying a target material into a vacuum chamber by using a nozzle and applying a laser beam to the target material, the target material is excited and turned into plasma. Various wavelength components including extreme ultraviolet (EUV) light are radiated from the plasma generated in this manner. Then, a desired wavelength component (e.g., 13.5 nm) among them is selectively reflected and collected by using a collector mirror, and outputted to an exposure unit (projection optics). For example, as a collector mirror for collecting EUV light having a wavelength near 13.5 nm, a mirror having a reflecting surface on which molybdenum (Mo) and silicon (Si) thin films are alternately stacked is used. Typically, the number of stacked Mo/Si thin films is from sixty to several hundreds. 
     As a related technology, Japanese Patent Application Publication JP-P2006-108686A discloses a lithography apparatus for applying EUV light to a virtual light source point of projection optics in alignment with an optical axis of the projection optics by providing an oblique incidence mirror within an EUV light source apparatus (radiation unit). 
     However, in JP-P2006-108686A, loss in EUV light intensity is caused by providing the oblique incidence mirror. Generally, the reflectance of EUV light by a mirror is about 60%, and therefore, the use efficiency of EUV light becomes lower by about 60% at each time one mirror is added. 
     Further, U.S. Patent Application Publication US 2006/0146413 A1 discloses a lithographic apparatus for applying EUV light to a virtual light source point of projection optics in alignment with an optical axis of the projection optics by placing an EUV light source apparatus obliquely relative to the direction of gravitational force. According to US 2006/0146413 A1, the number of reflection mirrors is reduced by one than that in JP-P2006-108686A, and therefore, the use efficiency of EUV light can be improved. 
     However, when the EUV light source apparatus is obliquely placed as in US 2006/0146413 A1, detachment of a chamber or a part of the chamber, movement to a maintenance area, and highly accurate placement relative to the projection optics become difficult in the case of maintenance of the EUV light source apparatus. 
     SUMMARY OF THE INVENTION 
     The present invention has been achieved in view of the above-mentioned problems. A purpose of the present invention is to provide an extreme ultraviolet light source apparatus by which detachment of a chamber or a part of the chamber, movement to a maintenance area, and highly accurate placement relative to projection optics can be performed easily for maintenance of the EUV light source apparatus. 
     In order to accomplish the above-mentioned purpose, an extreme ultraviolet light source apparatus according to one aspect of the present invention is an apparatus for generating plasma by applying a laser beam to a target material and entering extreme ultraviolet light radiated from the plasma into projection optics of exposure equipment, and the apparatus includes: a chamber in which the extreme ultraviolet light is generated; a target supply unit for supplying the target material into the chamber; a driver laser for applying the laser beam to the target material supplied by the target supply unit to generate the plasma; a collector mirror for collecting the extreme ultraviolet light radiated from the plasma; a positioning mechanism for positioning at least a part of the chamber in a predetermined location where an optical axis of the collected extreme ultraviolet light and an optical axis of the projection optics of the exposure equipment are aligned with each other; and a movement mechanism for moving at least the part of the chamber positioned in the predetermined location between the predetermined location and a maintenance area. 
     According to the present invention, since the positioning mechanism for positioning the chamber or a part of the chamber requiring maintenance in the predetermined location and the movement mechanism for moving the chamber or the part of the chamber between the predetermined location and the maintenance area are provided, detachment of the chamber or the part of the chamber, movement to the maintenance area, and highly accurate placement relative to the projection optics can be performed easily for maintenance of the EUV light source apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are a plan view and a side view showing an overall configuration of exposure equipment including an extreme ultraviolet (EUV) light source apparatus according to one embodiment of the invention; 
         FIG. 2  is a schematic diagram showing an outline of a chamber and peripheral devices forming the EUV light source apparatus; 
         FIGS. 3A and 3B  are a plan view and a side view showing a first example related to a movement mechanism and a positioning mechanism of the EUV light source apparatus; 
         FIGS. 4A and 4B  are a plan view and a side view showing a second example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 5A and 5B  are a plan view and a side view showing a third example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 6A and 6B  are a plan view and a side view showing a fourth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 7A and 7B  are a plan view and a side view showing a fifth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 8A and 8B  are a plan view and a side view showing a sixth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 9A-9C  are a plan view, a side view, and a rear view showing a seventh example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 10A and 10B  are a plan view and a side view showing an eighth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 11A and 11B  are a plan view and a side view showing a ninth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 12A and 12B  are a plan view and a side view showing a tenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 13A and 13B  are a plan view and a side view showing an eleventh example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 14A and 14B  are a plan view and a side view showing a twelfth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 15A and 15B  are a plan view and a side view showing a thirteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIGS. 16A and 16B  are a plan view and a side view showing a fourteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 17  is a rear view showing a fifteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 18  is a rear view showing a sixteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 19  is a rear view showing a seventeenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 20  is a rear view showing an eighteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 21  is a rear view showing a nineteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 22  is a rear view showing a twentieth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 23  is a rear view showing a twenty-first example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 24  is a rear view showing a twenty-second example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 25  is a rear view showing a twenty-third example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 26  is a rear view showing a twenty-fourth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 27  is a rear view showing a twenty-fifth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 28  is a rear view showing a twenty-sixth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 29  is a rear view showing a twenty-seventh example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 30  is a rear view showing a twenty-eighth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus; 
         FIG. 31  is a side view showing a twenty-ninth example related to a connection part between the EUV light source apparatus and projection optics; 
         FIGS. 32A and 32B  are a plan view and a side view showing a thirtieth example related to a configuration in which only a part of the chamber of the EUV light source apparatus is moved; and 
         FIGS. 33A and 33B  are a plan view and a side view showing a thirty-first example related to the configuration in which only a part of the chamber of the EUV light source apparatus is moved. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention will be explained in detail by referring to the drawings. The same reference numerals are assigned to the same component elements and the description thereof will be omitted. 
       FIGS. 1A and 1B  are a plan view and a side view showing an overall configuration of exposure equipment including an extreme ultraviolet (EUV) light source apparatus according to one embodiment of the invention. The exposure equipment includes an EUV light source apparatus  1  and projection optics  20 . 
     The EUV light source apparatus  1  employs a laser produced plasma (LPP) system for generating EUV light by applying a laser beam to a target material for excitation. As shown in  FIGS. 1A and 1B , the EUV light source apparatus  1  has a chamber  10  in which EUV light is generated, a movement mechanism  60 , and a positioning mechanism  70 . The chamber  10  is a vacuum chamber in which extreme ultraviolet light is generated. 
       FIG. 2  is a schematic diagram showing an outline of the chamber and peripheral devices forming the EUV light source apparatus. The EUV light source apparatus  1  has a droplet generator  11 , a droplet catcher  16 , a driver laser  30 , and a flexible pipe  92  as shown in  FIG. 2  in addition to the chamber  10 , the movement mechanism  60 , and the positioning mechanism  70  as shown in  FIGS. 1A and 1B . 
     The droplet generator  11  is a unit for supplying a target material of tin (Sn), lithium (Li), or the like to be used for generating EUV light into the chamber  10  via a target nozzle  12 . Here, the droplet generator  11  corresponds to a target supply unit for supplying the target material into the chamber. Among the supplied target material, the unnecessary material, to which the laser beam has not been applied, is collected by the droplet catcher  16 . 
     The state of the target material may be solid, liquid, or gas, and the target material may be supplied to a space within the chamber  10  in any known form such as continuous flow (target jet) or droplets. For example, when a melted metal of tin (Sn) is used as the target material, the droplet generator  11  includes a heater for melting Sn, a compressed gas cylinder for supplying a high-purity Ar gas for injecting the melted metal Sn, a mass flow controller, a target nozzle, and so on. Further, in the case where droplets are generated, a vibrating unit such as a piezoelectric element is added to the target nozzle. 
     The driver laser  30  is a master oscillator power amplifier type laser apparatus for generating a driving laser beam to be used for excitation of the target material. The laser beam generated by the driver laser  30  is focused via a laser beam focusing optics  35  including at least one lens and/or at least one mirror and a laser beam introduction chamber window  34  for passing the laser beam into the chamber  10 , so as to form a focal point on the trajectory of the target material within the chamber  10 . When the laser beam is applied to the target material, plasma is generated, and light having various wavelengths is radiated from it. 
     Within the chamber  10 , an EUV collector mirror  15  is provided. The reflection surface of the EUV collector mirror  15  is coated with a multilayer film that reflects EUV light having a specific wavelength component (e.g., 13.5 nm) among the light having various wavelengths radiated from the plasma, at high reflectance. The reflection surface of the EUV collector mirror  15  has an ellipsoidal shape. The EUV collector mirror  15  is provided such that the first focal point of the ellipse is located at a plasma emission point (PP), and the EUV light is focused on the second focal point of the ellipse as an intermediate focus point (IF). 
     The flexible pipe  92  for allowing the EUV light emitted from the EUV collector mirror  15  to enter the projection optics  20  is connected between the chamber  10  and the projection optics  20 . The flexible pipe  92  will be described later in the explanation of  FIG. 31 . 
     Referring to  FIGS. 1A and 1B  again, the projection optics  20  has a mask radiation unit  21  for illumination of a mask, and a workpiece radiation unit  22  for projection exposure of the mask image on a workpiece such as a wafer. The mask radiation unit  21  applies the EUV light entering from the EUV light source apparatus  1  onto a mask pattern of a mask table MT via reflection optics. The workpiece radiation unit  22  focuses the EUV light reflected from the mask table MT on the workpiece (semiconductor wafer or the like) disposed on a workpiece table WT via reflection optics. Then, the mask table MT and the workpiece table WT are moved in parallel at the same time, and the mask pattern is transcribed to the workpiece. 
     The positioning mechanism  70  includes a chamber support  74   a  conformed to the shape of the chamber  10 . The chamber support  74   a  holds the chamber  10  in a position oblique relative to the direction of gravitational force such that the optical axis of the EUV light emitted from the EUV collector mirror  15  is aligned with the optical axis of the projection optics  20 . Since the chamber support  74   a  is conformed to the chamber  10 , the chamber  10  is fit in the chamber support  74   a , and thereby, the chamber  10  can be properly held in the posture in which the optical axis of the EUV light emitted from the EUV collector mirror  15  is aligned with the optical axis of the projection optics  20 . 
     The positioning mechanism  70  positions the chamber support  74   a  such that the chamber  10  is positioned in a predetermined location where the optical axis of the EUV light emitted from the EUV collector mirror  15  is aligned with the optical axis of the projection optics  20 . The details of the configuration of positioning the chamber support  74   a  will be described later, and various configurations such as stoppers, positioning pins, or six-axis stage may be used. In  FIGS. 1A and 1B , the state in which the chamber  10  is positioned in the predetermined location in alignment with the optical axis of the projection optics  20  together with the chamber support  74   a  is shown by solid lines. 
     The movement mechanism  60  is a mechanism of moving the chamber  10  between the predetermined location where the chamber  10  is positioned by the positioning mechanism  70  and a maintenance area in which maintenance can be done. The details of the movement mechanism  60  will be described later, and various configurations such as rails and wheels, a crane, and an air generator may be used. In  FIGS. 1A and 1B , the state in which the chamber  10  is moved to the maintenance area together with the chamber support  74   a  is shown by broken lines. 
     In the configuration as described above, according to the embodiment, the EUV light source apparatus  1  can be placed in an oblique condition with high accuracy such that the optical axis of the EUV light emitted from the EUV collector mirror  15  is aligned with the optical axis of the projection optics  20  of the exposure equipment. On the other hand, at maintenance of the chamber  10  of the EUV light source apparatus  1 , the chamber  10  can be detached from the projection optics  20  in safety. Further, after maintenance of the chamber  10 , the chamber  10  can be placed with high accuracy relative to the projection optics  20 . Furthermore, detachment and placement for maintenance of the chamber  10  can be performed in a short time. 
     Next, a specific configuration example of the EUV light source apparatus of the above-mentioned embodiment will be explained. 
       FIGS. 3A and 3B  are a plan view and a side view showing a first example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 3A and 3B , the EUV light source apparatus  1  according to the first example includes, as the movement mechanism  60 , two parallel rails  61  placed on the floor. Wheels  81   a  are attached to the chamber support  74   a . As the wheels  81   a  roll along the rails  61 , the chamber support  74   a  moves together with the chamber  10 . In addition, sliding bearings may be used in place of the wheels  81   a . Further, also in the following explanation, sliding bearings may be used in place of the wheels  81   a.    
     Furthermore, the EUV light source apparatus  1  according to the first example includes, as the positioning mechanism  70 , a positioning block  71   a  placed in a location at the same side as the projection optics  20 , and a fixing plate  72  placed in a location at the opposite side to the projection optics  20 . Members for fixing the chamber support  74   a  in contact therewith are provided on the fixing plate  72 . 
     The positioning block  71   a  is constantly placed on the rails  61 , and regulates the movement of the chamber support  74   a  toward the projection optics  20 . The fixing plate  72  is placed on the rails  61  under the condition that the chamber support  74   a  is pressed against the positioning block  71   a , and secured by bolts  73   a  or pins to regulate the movement of the chamber support  74   a  toward the opposite side to the projection optics  20 . 
     By the positioning block  71   a  and the fixing plate  72 , the movement of the chamber support  74   a  and the chamber  10  along the traveling direction on the rails  61  is regulated, and the chamber  10  is positioned in the predetermined location in alignment with the optical axis of the projection optics  20 . At maintenance of the chamber  10 , the bolts  73   a  and the fixing plate  72  are detached and the chamber support  74   a  is moved to the location as shown by the broken lines in  FIGS. 3A and 3B . 
     In the embodiment, the rails  61  are provided on the floor and the wheels  81   a  are provided to the chamber support  74   a . However, the invention is not limited to that, and the wheels may be provided to the floor and the rails may be provided on the chamber support  74   a . In this case, for example, four wheels are placed on the floor and rails are placed under the chamber support  74   a , and thereby, movement and positioning can be easily performed. 
       FIGS. 4A and 4B  are a plan view and a side view showing a second example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 4A and 4B , in the EUV light source apparatus  1  according to the second example, as the movement mechanism, wheels  81   a  are provided to the chamber support  74   a  and guide rails  64   a  are provided on a floor (or a base plate surface within an apparatus), respectively. The chamber support  74   a  on which the chamber  10  is mounted moves as the wheels  81   a  roll on the floor. In the first example as shown in  FIGS. 3A and 3B , the rails  61  on the floor are provided from the positioning block  71   a  through the fixing location of the fixing plate  72  to the maintenance area. On the other hand, in the second example, the guide rails  64   a  are provided only from the location of the positioning block  71   a  to the fixing location of the fixing plate  72 , and the guide rails  64   a  are not provided to the maintenance area. 
     Therefore, in the second example, the chamber support  74   a , on which the chamber  10  is mounted, can travel without regulation of the guide rails  64   a  in the maintenance area, while its traveling path is regulated by the guide rails  64   a  between the location of the positioning block  71   a  and the fixing location of the fixing plate  72 . The chamber  10  in the longitudinal direction of the guide rails  64   a  is positioned by the positioning block  71   a  in contact with the front end of the chamber support  74   a  and the fixing plate  72  in contact with the rear end of the chamber support  74   a , in the same way as in the first example. Alternatively, instead of the positioning block  71   a , the same positioning member as the fixing plate  72  may be fixed in the location in contact with the front end of the chamber support  74   a.    
     According to the second example, the degree of freedom of movement of the chamber  10  in the maintenance area can be improved, and handling of the chamber  10  can be facilitated. In addition, as the configuration for regulating the traveling path of the chamber support  74   a  by the guide rails  64   a , grooves for receiving the guide rails  64   a  may be formed on the lower surface of the chamber support  74   a . Alternatively, as shown in  FIG. 18 , which will be explained later, protrusions may be provided on the lower surface of the chamber support  74   a , and grooves for receiving the protrusions may be formed in the guide rails  64   a.    
       FIGS. 5A and 5B  are a plan view and a side view showing a third example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 5A and 5B , in the EUV light source apparatus  1  according to the third example, as the movement mechanism, wheels  81   a  are provided to the chamber support  74   a . The chamber support  74   a , on which the chamber  10  is mounted, moves as the wheels  81   a  roll on the floor. In the second example as shown in  FIGS. 4A and 4B , the guide rails  64   a  are provided from the location of the positioning block  71   a  to the fixing location of the fixing plate  72 . On the other hand, in the third example, guide pieces  64   b  are provided only near the location where the positioning block  71   a  is placed, and the guide pieces  64   b  are not provided to the fixing location of the fixing plate  72  and the maintenance area. 
     Therefore, in the third example, the chamber support  74   a , on which the chamber  10  is mounted, can travel without regulation of the guide pieces  64   b . The guide pieces  64   b  position the chamber support  74   a  in a direction perpendicular to the traveling direction by the wheels  81   a . Positioning of the chamber support  74   a  in a direction in parallel to the raveling direction by the wheels  81   a  is performed by the positioning block  71   a  in contact with the front end of the chamber support  74   a  and the fixing plate  72  in contact with the rear end of the chamber support  74   a . Alternatively, instead of the positioning block  71   a , the same positioning member as the fixing plate  72  may be fixed in the location in contact with the front end of the chamber support  74   a.    
     According to the third example, the degree of freedom of movement of the chamber  10  except in the case requiring positioning can be improved, and handling of the chamber  10  can be facilitated. Note that, in order to position the chamber  10  by using the guide pieces  64   b , grooves for receiving the guide pieces  64   b  may be formed in the chamber support  74   a  with the chamber  10  mounted thereon, for example. 
       FIGS. 6A and 6B  are a plan view and a side view showing a fourth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 6A and 6B , the EUV light source apparatus  1  according to the fourth example is different from the first example as shown in  FIGS. 3A and 3B  in that the chamber  10  moves in a direction crossing the direction toward the projection optics  20 . Accordingly, in the fourth example, the rails  61  are placed in the direction crossing the direction toward the projection optics  20 . Further, positioning of the chamber  10  in the direction crossing the direction toward the projection optics  20  is performed by the positioning block  71   a  and the fixing plate  72 . The rest of the configuration is the same as that in the first example, and the chamber support  74   a  moves together with the chamber  10  as the wheels  81   a  roll along the rails  61 . Although the example in which the chamber  10  moves to the right of the projection optics  20  (downwards in  FIG. 6A ) is shown, the chamber may move to the left (upwards in  FIG. 6A ). 
       FIGS. 7A and 7B  are a plan view and a side view showing a fifth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 7A and 7B , the EUV light source apparatus  1  according to the fifth example is different from the second example as shown in  FIGS. 4A and 4B  in that the chamber  10  moves in a direction crossing the direction toward the projection optics  20 . Accordingly, in the fifth example, the guide rails  64   a  are placed in the direction crossing the direction toward the projection optics  20 . Further, positioning of the chamber  10  in the direction crossing the direction toward the projection optics  20  is performed by the positioning block  71   a  and the fixing plate  72 . The rest of the configuration is the same as that of the second example. The chamber  10  moves in a direction in parallel to the longitudinal direction of the guide rails  64   a , and thereby, moves between a predetermined direction in contact with the positioning block  71   a  and the maintenance area where guide rails  64   a  are not provided. Although the example in which the chamber  10  moves to the right of the projection optics  20  (downwards in  FIG. 7A ) is shown, the chamber may move to the left (upwards in  FIG. 7A ). 
       FIGS. 8A and 8B  are a plan view and a side view showing a sixth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 8A and 8B , the EUV light source apparatus  1  according to the sixth example is different from the third example as shown in  FIGS. 5A and 5B  in that the chamber  10  moves in a direction crossing the direction toward the projection optics  20 . Accordingly, in the sixth example, positioning of the chamber  10  in the direction crossing the direction toward the projection optics  20  is performed by the positioning block  71   a  and the fixing plate  72 . The rest of the configuration is the same as that of the third example. The chamber  10  moves in the direction crossing the direction toward the projection optics  20 , and thereby, moves between a predetermined direction in contact with the positioning block  71   a  and the maintenance area. Although the example in which the chamber  10  moves to the right of the projection optics  20  (downwards in  FIG. 8A ) is shown, the chamber may move to the left (upwards in  FIG. 8A ). 
       FIGS. 9A-9C  are a plan view, a side view, and a rear view showing a seventh example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 9A-9C , the EUV light source apparatus  1  according to the seventh example includes, as the movement mechanism  60 , a crane  62  with wheels. The crane  62  hoists the chamber  10  and the wheels roll on the floor, and thereby, the chamber  10  is moved. The chamber  10  is provided with a hanging ring for hoisting by the crane  62 . The hanging ring is provided in a location just above the center of gravity of the chamber  10  under the condition that the chamber  10  is positioned in a predetermined location where the optical axis of EUV light emitted from the EUV collector mirror  15  is aligned with the optical axis of the projection optics  20 . Thereby, sudden inclination of the chamber can be prevented when the chamber is hoisted by the crane  62 . 
     Further, the EUV light source apparatus  1  according to the seventh example includes, as the positioning mechanism  70 , a positioning stage  74   b  fixed on the floor. The positioning stage  74   b  holds the chamber  10  in a posture oblique relative to the gravity direction such that the optical axis of EUV light emitted from the EUV collector mirror  15  is aligned with the optical axis of the projection optics  20 . Since the positioning stage  74   b  is conformed to the shape of the chamber  10 , when the chamber  10  is fitted in the positioning stage  74   b , the chamber  10  can be correctly held in a posture in which the optical axis of EUV light emitted from the EUV collector mirror  15  is aligned with the optical axis of the projection optics  20 . In addition, the chamber  10  may be positioned on the positioning stage  74   b  by providing positioning pins on the positioning stage  74   b , or may be fixed onto the positioning stage  74   b  with bolts. At maintenance of the chamber  10 , the chamber  10  is moved by the crane  62  to the location as shown by broken lines in  FIGS. 9A and 9B . 
     The crane  62  may be permanently installed or brought in only for maintenance. Although the wheels of the crane  62  travel on the floor, the present invention is not limited to that, but rails may be provided on the floor for the wheels to travel on the rails. Furthermore, although the crane  62  is shown as an example of the movement mechanism  60 , the present invention is not limited to that, but the chamber  10  may be lifted by a lifter and moved to the maintenance area. Moreover, although the positioning stage  74   b  fixed on the floor is shown as an example of the positioning mechanism  70 , the present invention is not limited to that, but a six-axis stage for high-accuracy adjustment of the optical axis of the chamber  10  may be used. 
       FIGS. 10A and 10B  are a plan view and a side view showing an eighth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 10A and 10B , the EUV light source apparatus  1  according to the eighth example includes, as the movement mechanism  60 , an air generating unit  63   a  provided on the lower surface of a chamber support  74   c . The air generating unit  63   a  ejects air to the floor (installation surface) from the lower surface of the air generating unit  63   a  by using a fan or the like to slightly raise the chamber support  74   c  from the floor for moving the chamber support  74   c  with low friction. 
     Further, the EUV light source apparatus  1  according to the eighth example includes, as the positioning mechanism  70 , two positioning pins  75   a  provided on the floor. The chamber support  74   c  is formed with notches for receiving the positioning pins  75   a . When the chamber support  74   c  is moved along the floor toward the projection optics  20  and the positioning pins  75   a  are pressed against the notches of the chamber support  74   c , the chamber support  74   c  is positioned together with the chamber  10 . The chamber support  74   c  is further fixed to the floor by a bolt  73   b . At maintenance of the chamber  10 , the bolt  73   b  is detached, and the chamber support  74   c  is moved by the air generating unit  63   a  to the location as shown by the broken lines in  FIGS. 10A and 10B . 
     According to the embodiment, the air generating unit  63   a  is used so that the chamber  10  can be moved by a simple configuration, and the chamber  10  can be positioned with high accuracy by using the simple positioning pins. 
     Although the two positioning pins  75   a  are provided, the present invention is not limited to that, but the larger number of positioning pins may be used. Further, for the positioning in the horizontal direction of the EUV chamber, positioning can be performed if locations of two points are determined, and therefore, not the positioning pins but blocks or plates that can determine the locations of two points may be used. 
       FIGS. 11A and 11B  are a plan view and a side view showing a ninth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 11A and 11B , the EUV light source apparatus  1  according to the ninth example includes, as the positioning mechanism  70 , an exposure equipment reference member  76  that also serves as a reference member for positioning the projection optics  20 . That is, the exposure equipment reference member  76  is used as the reference for positioning the projection optics  20  and also used as the reference for positioning the chamber  10 . The exposure equipment reference member  76  is a large member having two plate parts orthogonal to each other with an L-shaped section in the thickness direction. One plate part positions the projection optics  20  and the other plate part positions the chamber  10 . The positioning of the chamber  10  is performed via the movement mechanism  60  and a positioning block  71   b  placed and fixed onto the exposure equipment reference member  76 . 
     According to the configuration, the positioning accuracy of the chamber  10  relative to the projection optics  20  can be improved and variance in the positioning accuracy depending on the installation location can be reduced. 
     The configuration of the movement mechanism  60  is not specifically limited, but a configuration described in the other examples may be used. The positioning mechanism  70  is not limited to the positioning block  71   b , but the mechanism described in the other examples may be used. The exposure equipment reference member  76  is not limited to the large member with the L-shaped section, but a member as reference such as small plates, pins, or the like may be placed in the projection optics  20 , and the movement mechanism and the positioning mechanism of the chamber  10  may be placed with reference to the reference member. 
       FIGS. 12A and 12B  are a plan view and a side view showing a tenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 12A and 12B , the EUV light source apparatus  1  according to the tenth example includes a laser beam introduction duct  31  for introducing a laser beam from the driver laser  30  provided outside of the chamber  10  into the chamber  10 . The laser beam introduction duct  31  includes a laser beam high-reflection mirror  32 , and a laser beam introduction flexible pipe  33 . Further, the chamber  10  is provided with a laser beam introduction chamber window  34  for transmitting the laser beam, and a laser beam focusing off-axis paraboloidal mirror  14  for focusing the laser beam on the target material. 
     The laser beam emitted from the driver laser  30  passes through the laser beam introduction duct  31 , is reflected by the laser beam high-reflection mirror  32  at an right angle, passes through the laser beam introduction flexible pipe  33 , is transmitted through the laser beam introduction chamber window  34 , and radiated into the chamber  10 . Further, the laser beam is reflected by the laser beam focusing off-axis paraboloidal mirror  14 , passes through an opening of the EUV collector mirror  15 , and is focused to the target material. 
     At maintenance of the chamber  10 , the laser beam introduction flexible pipe  33  is detached, and the chamber  10  is moved by the movement mechanism  60  to the location as shown by the broken lines in  FIGS. 12A and 12B . 
     The embodiment is characterized in that the laser beam introduction duct  31  and the laser beam introduction flexible pipe  33  are provided outside the track on which the chamber is moved by the movement mechanism  60 . Therefore, the laser beam introduction duct  31  and the laser beam introduction flexible pipe  33  are not an obstacle of the maintenance of the chamber  10 . Further, even when the maintenance of the chamber  10  is done, the optical axis of the laser beam is not changed. Thus, if the chamber  10  is correctly positioned, it can be correctly positioned relative to both the optical axis of the laser beam and the optical axis of the projection optics  20 . 
       FIGS. 13A and 13B  are a plan view and a side view showing an eleventh example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 13A and 13B , the EUV light source apparatus  1  according to the eleventh example includes a vacuum evacuation pump  41  and a vacuum evacuation pump flexible pipe  43  outside of the chamber  10  in addition to the configuration of the tenth example. Further, the chamber  10  is provided with a gate valve  44  connected to the vacuum evacuation pump flexible pipe  43 . 
     The vacuum evacuation pump  41  evacuates the air within the chamber  10  via the gate valve  44  and the vacuum evacuation pump flexible pipe  43 , and thereby, provides a good environment for transmission of EUV light. Further, since the vacuum evacuation pump flexible pipe  43  is provided, the vibration of the vacuum evacuation pump  41  can be prevented from propagating to the chamber  10 . 
     At maintenance of the chamber  10 , the gate valve  44  is closed, and the vacuum evacuation pump flexible pipe  43  and the laser beam introduction flexible pipe  33  are detached, and the chamber  10  is moved by the movement mechanism  60  to the location as shown by the broken lines in  FIGS. 13A and 13B . 
     The embodiment is characterized in that the vacuum evacuation pump  41  and the vacuum evacuation pump flexible pipe  43  are provided outside the track on which the chamber is moved by the movement mechanism  60 . Therefore, the vacuum evacuation pump  41  and the vacuum evacuation pump flexible pipe  43  are not an obstacle of the maintenance of the chamber  10 . 
       FIGS. 14A and 14B  are a plan view and a side view showing a twelfth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 14A and 14B , the EUV light source apparatus  1  according to the twelfth example includes a pair of magnets  51  and  52  placed such that the magnetic field direction is along the horizontal direction, and magnet fixing stages  53  and  54  for fixing the magnets, outside of the chamber  10  in addition to the configuration of the eleventh example. The pair of magnets  51  and  52  are superconducting electromagnets for trapping charged particles radiated from plasma generated within the chamber  10  and preventing deterioration of the EUV collector mirror  15 , and have large weights for generating a strong magnetic field. 
     At maintenance of the chamber  10 , a gate valve  44   a  is closed, and a vacuum evacuation pump flexible pipe  43   a  and the laser beam introduction flexible pipe  33  are detached, and the chamber  10  is moved by the movement mechanism  60  to the location as shown by the broken lines in  FIGS. 14A and 14B . Here, it is not necessary to move the magnets  51  and  52  and the magnet fixing stages  53  and  54 . 
     The embodiment is characterized in that the pair of magnets  51  and  52  are provided separably from the chamber  10 , outside the track on which the chamber is moved by the movement mechanism  60 . Therefore, the magnets  51  and  52  are not obstacles of the maintenance of the chamber  10 . 
     In the embodiment, the vacuum evacuation pump  41  is provided outside the track on which the chamber is moved by the movement mechanism  60  as is the case of the eleventh example. However, the pipe, which includes the vacuum evacuation pump flexible pipe  43   a , for the vacuum evacuation pump  41  and the gate valve  44   a  are provided in an area partially overlapping the track on which the chamber is moved by the movement mechanism  60 . At maintenance of the chamber  10 , they can be retracted to the outside of the track on which the chamber is moved by the movement mechanism  60  by bending the vacuum evacuation pump flexible pipe  43   a.    
       FIGS. 15A and 15B  are a plan view and a side view showing a thirteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 15A and 15B , in the EUV light source apparatus  1  according to the thirteenth example, the chamber  10  moves in a direction crossing the direction toward the projection optics  20 . Accordingly, wheels  55  are provided to a magnet fixing stage  54   a  with a magnet  52   a  mounted thereon so that the magnet  52   a  existing on the movement track of the chamber  10  can be retracted to the outside of the movement track of the chamber  10 . In the thirteenth example, as the wheels  55  roll on the floor, the magnet fixing stage  54   a  can be moved in the direction crossing the movement track of the chamber  10 . The configuration for moving and positioning the chamber  10  is the same as that of the fifth example as shown in  FIGS. 7A and 7B . Although the example in which the magnet  52   a  is retracted to the outside of the movement track of the chamber  10  is shown, in the case where the vacuum evacuation pump or the other large parts are on the movement track of the chamber  10 , they may be retracted. Further, although the example in which the magnet  52   a  is retracted and the chamber  10  is moved to the right of the projection optics  20  (downwards in  FIG. 15A ) is shown, the magnet  51  may be retracted and the chamber  10  may be moved to the left (upwards in  FIG. 15A ). Furthermore, the mechanism for moving the magnet  52   a  is not limited to the wheels  55 , but rails or sliding bearings may be used. 
       FIGS. 16A and 163  are a plan view and a side view showing a fourteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIGS. 16A and 16B , in the EUV light source apparatus  1  according to the fourteenth example, the chamber  10  moves in a direction crossing the direction toward the projection optics  20 . Accordingly, a rotational shaft  56  and wheels  57  are provided to a magnet fixing stage  54   b  with a magnet  52   b  mounted thereon so that the magnet  52   b  existing on the movement track of the chamber  10  can be retracted to the outside of the movement track of the chamber  10 . In the fourteenth example, as the magnet fixing stage  54   b  is rotated around the rotational axis  56 , the magnet fixing stage  54   b  can be moved. The configuration for moving and positioning the chamber  10  is the same as that of the fifth example as shown in  FIGS. 7A and 7B . Although the example in which the magnet  52   b  is retracted to the outside of the movement track of the chamber  10  is shown, in the case where the vacuum evacuation pump or the other large parts are on the movement track of the chamber  10 , they may be retracted. Further, although the example in which the magnet  52   b  is retracted and the chamber  10  is moved to the right of the projection optics  20  (downwards in  FIG. 16A ) is shown, the magnet  51  may be retracted and the chamber may be moved to the left (upwards in  FIG. 16A ). Furthermore, in place of the wheels  57 , sliding bearings may be used. 
       FIG. 17  is a rear view showing a fifteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 17 , the EUV light source apparatus  1  according to the fifteenth example is similar to the first example in that the EUV light source apparatus  1  includes two parallel rails  61   a  as the movement mechanism  60 , and the chamber  10  moves as wheels  81   a  roll along the rails  61   a . On the other hand, the fifteenth example is different from the first example in that a run-off prevention guide formed with a run-off prevention guide groove  64  is additionally provided in parallel to the rails  61   a , and a run-off prevention piece  84  slides to move in the run-off prevention guide groove  64  so as to prevent the run-off of the chamber  10 . The rails  61   a  and the run-off prevention guide are fixed onto a movement mechanism installation base  67 , and the movement mechanism installation base  67  is fixed to the floor by anchor bolts  68 . 
     As the positioning mechanism to be used in the fifteenth example, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIG. 18  is a rear view showing a sixteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 18 , the EUV light source apparatus  1  according to the sixteenth example is similar to the fifteenth example as shown in  FIG. 17  in that the chamber  10  moves as wheels  81   a  attached to the chamber  10  roll, and a guide formed with a guide groove  64   c  is provided in parallel to the direction toward the projection optics  20  on a base  67   c , and a protrusion  84   a  provided on the chamber  10  slides to move in the guide groove  64   c  so as to regulate the traveling path of the chamber. On the other hand, the sixteenth example is different from the fifteenth example in that the wheels  81   a  roll not on the rails but on the base  67   c  or the floor. The guide may be provided in the entire traveling path from the location where the chamber  10  is positioned to the maintenance area, or may be provided only in a part of the traveling path. 
       FIG. 19  is a rear view showing a seventeenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 19 , the EUV light source apparatus  1  according to the seventeenth example is different from the sixteenth example as shown in  FIG. 18  in that two guides respectively formed with two guide grooves  64   c  are provided at the outer side than the traveling path of the wheels  81   a , and corresponding plural protrusions  84   a  are provided at the outer side than the wheels  81   a , and the wheels  81   a  are provided at the inner side thereof. The rest of the configuration is the same as that of the sixteenth example. 
       FIG. 20  is a rear view showing an eighteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 20 , the EUV light source apparatus  1  according to the eighteenth example is similar to the first example in that the EUV light source apparatus  1  includes two parallel rails  61   b  as the movement mechanism  60 , and the chamber  10  moves as wheels  81   b  roll along the rails  61   b . On the other hand, the eighteenth example is different from the first example in that the run-off of the chamber  10  is prevented by flanges formed on the side surfaces of the wheels  81   b . The rails  61   b  are fixed onto the movement mechanism installation base  67 , and the movement mechanism installation base  67  is fixed to the floor by the anchor bolts  68 . 
     As the positioning mechanism  70  to be used in the eighteenth example, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIG. 21  is a rear view showing a nineteenth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 21 , the EUV light source apparatus  1  according to the nineteenth example is similar to the first example in that the EUV light source apparatus  1  includes two parallel rails  61   c  and  65  as the movement mechanism  60 , and the chamber  10  moves as a wheel  81   c  rolls along the rail  61   c  and a wheel  85  rolls along the rail  65 . On the other hand, the nineteenth example is different from the first example in that the section perpendicular to the longitudinal direction of the rail  65  within the rails  61   c  and  65  has a convex or concave shape, the section along the diameter of the wheel  85  rolling along the rail  65  has a concave or convex shape corresponding to the rail  65 , and thereby, the run-off of the chamber  10  is prevented. The rails  61   c  and  65  are fixed onto the movement mechanism installation base  67  and the movement mechanism installation base  67  is fixed to the floor by the anchor bolts  68 . 
     As the positioning mechanism  70  to be used in the nineteenth example, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIG. 22  is a rear view showing a twentieth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 22 , the EUV light source apparatus  1  according to the twentieth example is similar to the first example in that the EUV light source apparatus  1  includes two parallel slide rails  61   d  as the movement mechanism  60  so that the chamber  10  moves. On the slide rails  61   d  in the twentieth example, slide blocks  81   d  are movably provided. Circulating balls are provided between the slide rails  61   d  and the slide blocks  81   d , and so-called linear bearings are formed. The slide blocks  81   d  are fixed to the chamber  10 , and the chamber  10  moves as the slide blocks  81   d  move. The slide rails  61   d  are fixed onto the movement mechanism installation base  67 , and the movement mechanism installation base  67  is fixed to the floor by anchor bolts  68 . 
     As the positioning mechanism to be used in the twentieth example, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIG. 23  is a rear view showing a twenty-first example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 23 , the EUV light source apparatus  1  according to the twenty-first example employs rack-and-pinions and the same run-off prevention guide groove as that in the fifteenth example as the movement mechanism  60 . That is, onto the movement mechanism installation base  67 , two racks  66   a  formed by gear-cutting on one surface of each elongated flat plate and the run-off prevention guide formed with the run-off prevention guide groove  64  are fixed in parallel to one another. Further, circular gears (pinions)  86   a  having small diameters and axially supported by the chamber  10  rotationally move on the racks  66   a  while engaging with the racks  66   a , and the run-off prevention piece  84  slides to move in the run-off prevention guide groove  64 , and thereby, the run-off of the chamber  10  is prevented. The movement mechanism installation base  67  is fixed to the floor by anchor bolts  68 . 
     As the positioning mechanism to be used in the twenty-first example, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIG. 24  is a rear view showing a twenty-second example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 24 , the EUV light source apparatus  1  according to the twenty-second example is similar to the twenty-first example in that the EUV light source apparatus  1  employs rack-and-pinions as the movement mechanism  60 . In the twenty-second example, racks  66   b  are of Riggenbach type having U-shaped sections, and the run-off of pinions  86   b  axially supported by the chamber  10  is prevented. Therefore, the run-off prevention guide groove  64  and the run-off prevention piece  84  as in the twenty-first example are not required. The racks  66   b  are fixed onto the movement mechanism installation base  67 , and the movement mechanism installation base  67  is fixed to the floor by the anchor bolts  68 . 
     As the positioning mechanism  70  to be used in the twenty-second example, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIGS. 25-29  are rear views showing the twenty-third to twenty-seventh examples related to the movement mechanism and the positioning mechanism of the EUV light source apparatus, respectively. 
     As shown in  FIGS. 25-29 , the EUV light source apparatuses  1  according to the twenty-third to twenty-seventh examples respectively include the same configurations of the fifteenth to twentieth and the twenty-second examples with respect to the movement mechanism  60 . In the fifteenth to twentieth and the twenty-second examples, the wheels  81   a  and the run-off prevention piece  84 , the wheels  81   b , the wheels  81   c  and  85 , the slide blocks  81   d , and the pinions  86   b  are axially supported by or fixed to the chamber  10 . On the other hand, in the twenty-third to twenty-seventh examples, they are axially supported by or fixed to a carriage  87 . Further, the chamber  10  is positioned on the carriage  87 , and moves to the maintenance area as the carriage  87  moves. 
     As the positioning mechanisms for positioning the carriage  87  in the twenty-third to twenty-seventh examples, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIG. 30  is a rear view showing a twenty-eighth example related to the movement mechanism and the positioning mechanism of the EUV light source apparatus. 
     As shown in  FIG. 30 , the EUV light source apparatus  1  according to the twenty-eighth example includes an air generating unit  63   b , which is the same as that in the eighth example, on the lower surface of the carriage  87 . Further, the chamber  10  is positioned on the carriage  87 , and moves to the maintenance area as the carriage  87  moves. 
     Positioning of the carriage  87  is the same as that in the eighth example in that two or more positioning pins  75   b  are used. However, in the twenty-eighth example, the positioning pins  75   b  are provided on a base  67   b . The base  67   b  is further placed on a movement mechanism installation base  67   a  via a guide mechanism such as slide rails like those in the twenty-sixth example. The movement mechanism installation base  67   a  is fixed to the floor by anchor bolts. According to the configuration, the carriage  87  with the chamber  10  mounted thereon moves toward the projection optics  20  together with the base  67   b  by the guide mechanism  69 , and is positioned in a predetermined location where the optical axes of the chamber  10  and the projection optics  20  are aligned with each other. 
     As the positioning mechanism for positioning the base  67   b  in the twenty-eighth example, the same configurations as the positioning block  71   a  and the fixing plate  72  in the first example may be used or the positioning mechanism  70  in the other examples may be used. 
       FIG. 31  is a side view showing a twenty-ninth example related to a connection part between the EUV light source apparatus  1  and the projection optics  20 . Both of the interior of the chamber  10  of the EUV light source apparatus  1  and the interior of the projection optics  20  are in a vacuum state or filled with a low-pressure gas for transmitting EUV light (e.g., an inert gas such as Ar or He, or a hydrogen gas, halogen gas, or halogenated hydrogen gas for etching of an adhered material) for use in order to provide good environment for transmitting EUV light. Accordingly, for easy maintenance of the chamber  10 , a gate valve  91   a  of the chamber  10  and a gate valve  91   b  of the projection optics  20  are provided in the connection part located in an optical path between the chamber  10  and the projection optics  20 , and a flexible pipe  92  is provided between the gate valve  91   a  and the gate valve  91   b . Further, in the flexible pipe  92 , a shield plate with pinhole  93  formed with a pinhole therein is fixed to the chamber  10  side. The EUV light is entered into the projection optics  20  through the pinhole. The shield plate with pinhole  93  prevents the target material or the like within the chamber  10  or the above-mentioned low-pressure gas for transmitting EUV light from entering the projection optics  20 . 
     As the movement mechanism and the positioning mechanism, not only the movement mechanisms and the positioning mechanisms described in the first to twenty-eighth examples but also any movement mechanism and positioning mechanism may be used. 
     At maintenance of the chamber  10 , first, the gate valve  91   a  of the chamber  10  and the gate valve  91   b  of the projection optics  20  are respectively closed. Then, in the case where the chamber  10  is filled with a low-pressure reactive gas (e.g., a hydrogen gas, halogen gas, or halogenated hydrogen gas), the gas is evacuated by a vacuum pump, and the chamber  10  is filled with an inert gas of nitrogen gas, argon gas, or the like to the degree of atmospheric pressure. Then, the flexible pipe  92  is detached, and the chamber  10  is moved to the location as shown by the broken lines of  FIG. 31  by the movement mechanism  60 . 
     For placement of the chamber  10 , through the opposite procedure to the above-mentioned procedure, first, the chamber  10  is moved toward the projection optics  20  by the movement mechanism  60 , and the chamber  10  is positioned in the predetermined location where the optical axes of the chamber  10  and the projection optics  20  are aligned with each other by the positioning mechanism  70 . Then, the flexible pipe  92  is connected between the gate valve  91   a  and the gate valve  91   b , and the interior of the flexible pipe is evacuated to the vacuum state by the vacuum evacuation pump. Then, the gate valve  91   a  of the chamber  10  and the gate valve  91   b  of the projection optics  20  are respectively opened. In this manner, the maintenance of the chamber  10  can be done without contamination of air within the chamber  10  and the projection optics  20 . 
       FIGS. 32A and 32B  are a plan view and a side view showing a thirtieth example related to a configuration in which only a part of the chamber  10  of the EUV light source apparatus is moved, and  FIGS. 33A and 33B  are a plan view and a side view showing a thirty-first example related to the configuration in which only a part of the chamber  10  of the EUV light source apparatus is moved. 
     The chamber  10  of the EUV light source apparatus  1  according to the thirtieth example as shown in  FIGS. 32A and 32B  is separable into a maintenance unit  10   a  at the plasma generation part side and an irregular maintenance unit  10   b  at the projection optics  20  side. In the embodiment, the large-diameter part near the plasma generation part of the chamber  10  is the maintenance unit  10   a , and the tapered part forming the optical path converging from the large-diameter part to the projection optics  20  side is the irregular maintenance unit  10   b.    
     Also in the thirty-first example as shown in  FIGS. 33A  and  33 B, the chamber  10  is also separable into a maintenance unit  10   c  at the plasma generation part side and an irregular maintenance unit  10   d  at the projection optics  20  side. The thirty-first embodiment is different from the thirtieth embodiment as shown in  FIGS. 32A and 32B  in that the tapered part of the chamber  10  is separated by a surface perpendicular to the movement direction by the movement mechanism  60 , and the part at the plasma generation part side with respect to the separation surface is the maintenance unit  10   c , and the part at the projection optics  20  side with respect to the separation surface is the irregular maintenance unit  10   d . According to the configuration, movement operation of the maintenance unit  10   c  to the maintenance area side and the coupling operation to the irregular maintenance unit  10   d  become easier. 
     As specifically shown in  FIGS. 33A and 33B , the maintenance unit  10   a  or  10   c  includes parts requiring regular maintenance such as the droplet generator  11 , the laser beam focusing off-axis paraboloidal mirror  14 , the EUV collector mirror  15 , the droplet catcher  16 , and a laser beam dumper  17 . That is, the droplet generator  11  is the unit for supplying a target material into the chamber  10 , and requires periodical replacement because clogging occurs in the target nozzle or the like after a long period of use. The laser beam focusing off-axis paraboloidal mirror  14  and the EUV collector mirror  15  require periodical replacement because its reflectance becomes lower during use by adherence of the target material, ion etching, or the like. The droplet catcher  16  is a unit for collecting the target material that has not been turned into plasma though supplied from the droplet generator  11 , and requires periodical replacement because it is contaminated by the target material during use. The laser beam dumper  17  is a unit for receiving the laser beam applied for excitation of the target material, and requires periodical replacement because the target material within the chamber  10  adheres to it during use. 
     On the other hand, the irregular maintenance unit  10   b  or  10   d  does not require the frequent maintenance like the maintenance unit  10   a  or  10   c . Accordingly, in these embodiments, only the maintenance unit  10   a  or  10   c  can be carried to the maintenance area. 
     In the joint part between the maintenance unit  10   a  or  10   c  and the irregular maintenance unit  10   b  or  10   d , an O-ring, a metal seal, or the like is embedded. Further, the maintenance unit  10   a  or  10   c  and the irregular maintenance unit  10   b  or  10   d  are united, clamped, and sealed by bolts, clamp, or the like. 
     As the movement mechanism and the positioning mechanism, not only the movement mechanisms and the positioning mechanisms described in the first to twenty-eighth examples but also any movement mechanism and positioning mechanism may be used. The movement mechanisms and the positioning mechanisms in the thirtieth and thirty-first examples moves and positions only the maintenance unit  10   a  or  10   c  of the chamber  10  for maintenance. 
     When the maintenance unit  10   a  or  10   c  is moved to the maintenance area, first, the chamber  10  is purged by an inert gas such as nitrogen gas or argon gas, and the gas is injected into the chamber  10  up to near the atmospheric pressure. Then, the bolts, clamp, or the like for uniting the maintenance unit  10   a  or  10   c  and the irregular maintenance unit  10   b  or  10   d  is detached. Then, the maintenance unit  10   a  or  10   c  is moved by the movement mechanism  60  to the maintenance area, and the separated maintenance unit  10   a  or  10   c  and irregular maintenance unit  10   b  or  10   d  are respectively closed by plates as lids. 
     For placement of the maintenance unit  10   a  or  10   c , through the opposite procedure to the above-mentioned procedure, first, the lids on the separation surface are respectively detached from the maintenance unit  10   a  or  10   c  on the movement mechanism  60  and the irregular maintenance unit  10   b  or  10   d  remaining at the projection optics  20  side. Then, the maintenance unit  10   a  or  10   c  is moved by the movement mechanism  60  to the irregular maintenance unit  10   b  or  10   d  side, and the maintenance unit  10   a  or  10   c  is positioned in the predetermined location where the optical axis of the EUV light is aligned with the optical axis of the projection optics  20  by the positioning mechanism  70 . Then, the maintenance unit  10   a  or  10   c  and the irregular maintenance unit  10   b  or  10   d  are united, clamped by bolts, clamp, or the like, and sealed. Then, the interior of the chamber  10  is evacuated by the vacuum evacuation pump.