Patent Publication Number: US-2021165319-A1

Title: Conveyance apparatus, lithography apparatus, and article manufacturing method

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a conveyance apparatus, a lithography apparatus, and an article manufacturing method. 
     Description of the Related Art 
     As demands for miniaturization of semiconductor devices, MEMS, and the like rise, a microprocessing technique of forming a pattern of an imprint material on a substrate by curing the imprint material while the imprint material on the substrate is in contact with a mold, a so-called imprint technique has attracted attention. According to an imprint apparatus that adopts the imprint technique, a microstructure on the order of several nanometers can be formed on a substrate. In addition, the imprint apparatus is used not only in manufacturing a semiconductor device and the like but also in manufacturing a replica (copy) mold from a master mold. 
     In the imprint apparatus, if particles are sandwiched between a substrate (an object onto which a pattern is transferred) and a mold (an object whose pattern is transferred), a defective pattern (manufacturing defect) is formed on the substrate, or the substrate or the mold is damaged. Therefore, in the imprint apparatus, it is important to suppress generation of particles and to convey and process the substrate and the mold in a space in which no particle is floating (exists). This is not limited to the imprint apparatus, and also in lithography apparatuses in general, for example, an exposure apparatus, it is unpreferable that particles adhere to a substrate or an original. Further, in a semiconductor device manufacturing process, along with the miniaturization of the pattern due to high integration of integrated circuits, more strict management is required for particles, particularly, dust and chemical contamination. 
     Therefore, in relation to particle management, a technique of collecting particles has been proposed in Japanese Patent Laid-Open No. 2016-39250. Japanese Patent Laid-Open No. 2016-39250 discloses a cleaning jig capable of collecting particles, which is related to a substrate conveyance mechanism including a holding member (hand) that holds a substrate and moves in a plurality of processing spaces. The cleaning jig is formed by a plate-like body in which a plurality of suction holes and connection ports for connecting the plurality of suction holes to a suction pump are formed. In Japanese Patent Laid-Open No. 2016-39250, the atmosphere (gas) in the vicinity of the suction holes is sucked (exhausted) via the suction holes and the connection ports while the cleaning jig is held by the holding member, thereby actively collecting particles existing in the vicinity of the suction holes. 
     However, the technique disclosed in Japanese Patent Laid-Open No. 2016-39250 requires the cleaning jig when collecting particles, so that the device cost increases, and the management and processing become complicated. Further, in the technique disclosed in Japanese Patent Laid-Open No. 2016-39250, in order to collect particles, the holding member must hold the cleaning jig instead of the substrate, so particles cannot be collected during the conveyance of the substrate. 
     SUMMARY OF THE INVENTION 
     The present invention provides a conveyance apparatus advantageous in particle management. 
     According to one aspect of the present invention, there is provided a conveyance apparatus that conveys an object to a processing space in which processing is performed using the object, including a hand configured to hold the object, and a moving unit configured to freely move the hand in the processing space, wherein the hand includes a suction hole provided in a surface different from a holding surface configured to come into contact with the object and hold the object, and a first flow path configured to allow the suction hole and an exhaust source to communicate with each other, and exhaust an atmosphere around the suction hole sucked via the exhaust source and the suction hole to an outside. 
     Further aspects of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing the configuration of a lithography system. 
         FIGS. 2A and 2B  are schematic views showing an example of the arrangement of a conveyance apparatus. 
         FIG. 3  is a view showing an example of a state in which the number of particles is counted. 
         FIG. 4  is a view showing another example of the state in which the number of particles is being counted. 
         FIGS. 5A to 5C  are schematic views showing an example of the arrangement of a conveyance apparatus. 
         FIG. 6  is a view showing an example of a state in which the number of particles is counted. 
         FIG. 7  is a view showing another example of the state in which the number of particles is counted. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but limitation is not made an invention that requires all such features, and multiple such features may be combined as appropriate. Furthermore, in the attached drawings, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted. 
     First Embodiment 
       FIG. 1  is a schematic view showing the configuration of a lithography system  100 . The lithography system  100  is a processing system including a conveyance apparatus  10 , a lithography apparatus  200 , and a preprocessing apparatus  300 . Note that in the following description, as shown in  FIG. 1 , directions will be indicated on an XYZ coordinate system in which directions parallel to the surface of a substrate  1  are defined as the X-Y plane. Directions parallel to the X-axis, the Y-axis, and the Z-axis of the XYZ coordinate system are the X direction, the Y direction, and the Z direction, respectively. 
     The lithography apparatus  200  is a processing apparatus that forms a pattern on the substrate  1 , and in this embodiment, a so-called cluster type processing apparatus including a plurality of processing units  210  (processing spaces) for performing processing of forming a pattern on the substrate  1 . However, the lithography apparatus  200  is not limited to the cluster type processing apparatus, and it may be a processing apparatus including a single processing unit. More specifically, the lithography apparatus  200  includes six processing units  210 A,  210 B,  210 C,  210 D,  210 E, and  210 F. In this embodiment, the lithography apparatus  200  is embodied as an imprint apparatus that forms a pattern of an imprint material on the substrate  1  using a mold serving as an original. However, the lithography apparatus  200  is not limited to the imprint apparatus, and it may be, for example, an exposure apparatus that transfers a pattern of a mask serving as an original onto the substrate  1  via a projection optical system. 
     The preprocessing apparatus  300  performs, on the substrate  1 , preprocessing required to form a pattern on the substrate  1  before forming the pattern on the substrate  1 , that is, before loading the substrate  1  to the lithography apparatus  200  via the conveyance apparatus  10 . For example, the preprocessing apparatus  300  includes a cleaning apparatus that cleans the substrate  1 , a coating apparatus that coats the substrate  1  with an adhesion layer, and the like. 
     The conveyance apparatus  10  is an apparatus that conveys an object (substrate or original) to the processing space in which processing is performed using the object. In this embodiment, the conveyance apparatus  10  conveys the substrate  1  between the preprocessing apparatus  300  and the lithography apparatus  200  via a substrate conveyance region  220  (conveyance path). 
       FIGS. 2A and 2B  are schematic views showing an example of the arrangement of the conveyance apparatus  10 .  FIG. 2A  is a plan view of the conveyance apparatus  10 , and  FIG. 2B  is a side view of the conveyance apparatus  10 . The conveyance apparatus  10  includes a hand  18  that holds the substrate  1  to convey the substrate  1 , and a moving unit  19  that freely moves the hand  18 . The substrate  1  is placed on the hand  18  almost horizontally with a processing target surface, which is a surface on which a pattern is to be formed, facing upward on the Z-axis. As shown in  FIG. 2B , the hand  18  includes a base member  181 , and a holding portion  13  that protrudes (extends in the Z-axis direction) from the base member  181  and defines a holding surface  131  for coming into contact with the substrate  1  and holding the substrate  1 . The hand  18  vacuum-chucks the substrate  1  on the holding surface  131  defined by the holding portion  13  in this embodiment, but the present invention is not limited to this. For example, a voltage may be applied to the holding portion  13  to generate a Coulomb force in the holding surface  131 , and the substrate  1  may be fixed by the Coulomb force. Note that since the holding portion  13  protrudes from the base member  181  as described above, only the holding portion  13  (holding surface  131 ) comes into contact with the substrate  1 . As shown in  FIG. 2A , two holding portions  13  are provided in the hand  18  in this embodiment, but the number of the holding portions  13  may be one, or may be three or more. The moving unit  19  freely moves the hand  18  in the substrate conveyance region  220  and each of the processing units  210 A to  210 F while the hand  18  is holding the substrate  1 . Any arrangement known in the art can be applied to the moving unit  19 . 
     As has been described above, since the substrate  1  is vacuum-chucked on the holding surface  131  defined by the holding portion  13  in this embodiment, the holding surface  131  is provided with a chuck hole  132 , and the chuck hole  132  communicates with a vacuum source VS via a vacuum flow path  14  (second flow path). An opening/closing valve  21  is provided in the vacuum flow path  14 . By opening the opening/closing valve  21  to exhaust the atmosphere (gas) in the vacuum flow path  14  to the outside by the vacuum source VS, the substrate  1  can be vacuum-chucked on the holding surface  131  via the chuck hole  132 . 
     Further, in this embodiment, the hand  18  is provided with suction holes  12   a  and  12   b . The suction holes  12   a  and  12   b  communicate with an exhaust source ES via an exhaust flow path  16 . More specifically, the suction hole  12   a  communicates with the exhaust source ES via an exhaust flow path  15   a  (first flow path), and the suction hole  12   b  communicates with the exhaust source ES via an exhaust flow path  15   b  (first flow path). The exhaust flow path  15   a  is a flow path for exhausting the atmosphere around the suction hole  12   a  sucked via the exhaust source ES and the suction hole  12   a  to the outside. The exhaust flow path  15   b  is a flow path for exhausting the atmosphere around the suction hole  12   b  sucked via the exhaust source ES and the suction hole  12   b  to the outside. The exhaust flow paths  15   a  and  15   b  and the vacuum flow path  14  are independent of each other (they form systems different from each other). As shown in  FIG. 2A , two suction holes  12   a  and  12   b  are provided in the hand  18  in this embodiment, but the number of the suction holes may be one, or may be three or more. 
     In this embodiment, a switch valve  22  is provided in the exhaust flow path  16  (exhaust flow paths  15   a  and  15   b ). The switch valve  22  functions as a switch mechanism that selectively switches between the communication of the exhaust source ES with the exhaust flow path  15   a  and that with the exhaust flow path  15   b . Note that the switch valve  22  also has a function of simultaneously allowing both the exhaust flow paths  15   a  and  15   b  to communicate with the exhaust source ES, and a function of blocking the communication of the exhaust source ES with both the exhaust flow paths  15   a  and  15   b . The switch valve  22  can be replaced with a simple opening/closing valve. 
     Further, in this embodiment, a counting unit  31  that counts the number of particles contained in the atmosphere to be exhausted to the outside via the exhaust flow path  16  (exhaust flow paths  15   a  and  15   b ) is provided between the switch valve  22  and the exhaust source ES. The counting unit  31  may not include an exhaust source. In addition, the counting unit  31  need not be provided in the lithography apparatus  200 , but may be shared by a plurality of apparatuses. In this case, the counting unit  31  may be provided in the exhaust flow path  16  as needed to count particles. The counting result of the particles obtained by the counting unit  31  is input to a generation unit  33  that has a function of generating a density distribution of particles and a function of specifying a place where particles are generated or flow in. 
     As shown in  FIG. 2B , the suction holes  12   a  and  12   b  are provided in a surface different from the holding surface  131 . With this arrangement, it becomes possible to exhaust the atmosphere around the suction holes  12   a  and  12   b  sucked via the exhaust source ES and the suction holes  12   a  and  12   b  to the outside via the exhaust flow path  16  (exhaust flow paths  15   a  and  15   b ) while the hand  18  is holding the substrate  1  on the holding surface  131 . Note that in this embodiment, the suction holes  12   a  and  12   b  are provided in a front surface  181   a  (first surface) of the base member  181  on the substrate  1  side on which the holding portion  13  is provided (that is, they are open to the substrate  1  side along the Z-axis direction). However, in this case, when particles are counted while the hand  18  is holding the substrate  1  on the holding surface  131 , the counting result of the particles may be influenced by the substrate  1 . If such influence may occur, the suction holes  12   a  and  12   b  may be provided in a back surface  181   b  (second surface) opposite to the front surface  181   a  of the base member  181  (that is, they may be open to the opposite side of the substrate  1  along the Z-axis direction). Alternatively, the suction holes  12   a  and  12   b  may be provided in a side surface  181   c  (third surface) orthogonal to the front surface  181   a  and the back surface  181   b  of the base member  181  (that is, they may be open along the X-axis direction). In other words, the suction holes  12   a  and  12   b  need only be provided in at least one of the front surface  181   a , the back surface  181   b , and the side surface  181   c  of the base member  181 . 
     Here, the particle management in the lithography system  100  will be described. As an index of air cleanness, it is customary to numerically indicate how many particles (dust) each having a particle size equal to or larger than 0.5 μm are present in the air per cubic foot (US Federal Air Cleanliness Standard 209E (abolished in November 2001)). Accordingly, as for an index for counting the number of particles by the counting unit  31 , it is necessary to collect the atmosphere of one cubic foot per minute. When the exhaust pressure of the exhaust source ES is −101.3 kPa (vacuum) with respect to the atmospheric pressure, in order to secure the above-described flow rate while considering the pressure loss, the opening cross-sectional area of each of the suction holes  12   a  and  12   b  is preferably equal to or larger than 4.8 mm 2 . Similarly, the opening cross-sectional area of each of the exhaust flow paths  15   a  and  15   b  is preferably equal to or larger than 4.8 mm 2 . 
       FIG. 3  is a view showing a state in which the conveyance apparatus  10  is counting, in the processing unit  210 C of the lithography apparatus  200 , the number of particles contained in the atmosphere in the processing unit  210 C. First, in a state in which the switch valve  22  allows both the exhaust flow paths  15   a  and  15   b  to communicate with the exhaust source ES, the counting unit  31  counts the number of particles in the entire atmosphere in the processing unit  210 C. Here, if a particle equal to or larger than a standard set in advance, for example, a particle having a particle size equal to or larger than 0.5 μm is counted (detected), the switch valve  22  sets a state in which either one of the exhaust flow paths  15   a  and  15   b  communicates with the exhaust source ES. The reason for allowing either one of the exhaust flow paths  15   a  and  15   b  to communicate with the exhaust source ES is to specify one of the suction holes  12   a  and  12   b  (the position thereof) from which particles are counted. Then, the moving unit  19  moves the hand  18  to each of a plurality of positions in the processing unit  210 C. Note that the plurality of positions are set in advance so as to cover (include) the entire processing unit  210 C. At this time, the counting unit  31  counts, at each of the plurality of positions in the processing unit  210 C, the number of particles contained in the atmosphere around the suction hole  12   a  or  12   b  to be exhausted to the outside via the exhaust flow path  15   a  or  15   b , respectively. The counting result of the particles at each of the plurality of positions in the processing unit  210 C (the number of particles at each of the plurality of positions in the processing unit  210 C counted by the counting unit  31 ) is input from the counting unit  31  to the generation unit  33 . The generation unit  33  generates the density distribution of particles in the processing unit  210 C based on the counting result of the particles at each of the plurality of positions in the processing unit  210 C, and specifies, from the density distribution, a place where particles are generated or flow in. Note that the generation unit  33  may provide the user with the density distribution of particles in the processing unit  210 C via, for example, a display apparatus such as a display. In this case, based on the density distribution of particles provided by the generation unit  33 , the user may specify a place where particles are generated or flow in. The processing as described above is not limited to the processing unit  210 C, and can be performed similarly in the other processing units  210 A,  210 B,  210 D,  210 E, and  210 F. 
       FIG. 4  is a view showing a state in which the conveyance apparatus  10  is counting, in the substrate conveyance region  220 , the number of particles contained in the atmosphere in the substrate conveyance region  220 . First, in a state in which the switch valve  22  allows both the exhaust flow paths  15   a  and  15   b  to communicate with the exhaust source ES, the counting unit  31  counts the number of particles in the entire atmosphere in the substrate conveyance region  220 . Here, if a particle equal to or larger than a standard set in advance, for example, a particle having a particle size equal to or larger than 0.5 μm is counted (detected), the switch valve  22  sets a state in which either one of the exhaust flow paths  15   a  and  15   b  communicates with the exhaust source ES. Then, the moving unit  19  moves the hand  18  to each of a plurality of positions in the substrate conveyance region  220 . Note that the plurality of positions are set in advance so as to cover (include) the entire substrate conveyance region  220 . At this time, the counting unit  31  counts, at each of the plurality of positions in the substrate conveyance region  220 , the number of particles contained in the atmosphere around the suction hole  12   a  or  12   b  to be exhausted to the outside via the exhaust flow path  15   a  or  15   b , respectively. The counting result of the particles at each of the plurality of positions in the substrate conveyance region  220  (the number of particles at each of the plurality of positions in the substrate conveyance region  220  counted by the counting unit  31 ) is input from the counting unit  31  to the generation unit  33 . The generation unit  33  generates the density distribution of particles in the substrate conveyance region  220  based on the counting result of the particles at each of the plurality of positions in the substrate conveyance region  220 , and specifies, from the density distribution, a place where particles are generated or flow in. Note that the generation unit  33  may provide the user with the density distribution of particles in the substrate conveyance region  220  via, for example, a display apparatus such as a display. In this case, based on the density distribution of particles provided by the generation unit  33 , the user may specify a place where particles are generated or flow in. 
     As has been described above, according to this embodiment, since the suction holes  12   a  and  12   b  are provided in the surface different from the holding surface  131 , it is possible to collect particles while the hand  18  is holding the substrate  1 , that is, during the conveyance of the substrate  1 . Further, in this embodiment, particles are collected at each of the plurality of positions in the apparatus while allowing either one of the exhaust flow paths  15   a  and  15   b  to communicate with the exhaust source ES, that is, while switching the communication of the exhaust source ES with the exhaust flow path  15   a  and that with the exhaust flow path  15   b . With this arrangement, it becomes possible to generate the density distribution of particles in the apparatus, and it is possible to quickly specify, from the density distribution of particles, a place where particles are generated or flow in. Note that in this embodiment, a new cleaning jig or the like is unnecessary to collect particles. Therefore, this embodiment is advantageous in particle management. 
     A case in which particles are collected during the conveyance of the substrate  1  has been described in this embodiment, but the present invention is not limited to this. Even in a state in which the hand  18  is not holding the substrate  1 , for example, even during maintenance or idling of the lithography system  100 , it is possible to collect particles in the apparatus. In other words, this embodiment can constantly collect particles in the apparatus. 
     Second Embodiment 
       FIGS. 5A to 5C  are schematic views showing an example of the arrangement of a conveyance apparatus  50  that conveys an original  2  to a lithography apparatus  200  (each of processing units  210 A to  210 E).  FIG. 5A  is a plan view of the conveyance apparatus  50 ,  FIG. 5B  is a side view of the conveyance apparatus  50 , and  FIG. 5C  is a front view of the conveyance apparatus  50 . The original  2  includes a pattern corresponding to a pattern to be formed on a substrate  1 . Although not shown in  FIG. 1 , the conveyance apparatus  50  is one of apparatuses forming a lithography system  100 . 
     The conveyance apparatus  50  includes a hand  58  that holds the original  2  to convey the original  2 , and a moving unit  59  that freely moves the hand  58 . The original  2  is placed on the hand  58  almost horizontally with a pattern surface, which is a surface with the pattern formed thereon, facing downward on the Z-axis. As shown in  FIG. 5B , the hand  58  includes a base member  581 , and a holding portion  51  that protrudes (extends in the Z-axis direction) from the base member  581  and defines a holding surface  511  for coming into contact with the original  2  and holding the original  2 . The hand  58  vacuum-chucks the original  2  on the holding surface  511  defined by the holding portion  51  in this embodiment, but the present invention is not limited to this. For example, a voltage may be applied to the holding portion  51  to generate a Coulomb force in the holding surface  511 , and the original  2  may be fixed by the Coulomb force. Note that since the holding portion  51  protrudes from the base member  581  as described above, only the holding portion  51  (holding surface  511 ) comes into contact with the original  2 . As shown in  FIG. 5A , four holding portions  51  are provided in the hand  58  in this embodiment, but the present invention is not limited to this, and the number of the holding portions  51  may be two or three, or may be five or more. The moving unit  59  freely moves the hand  58  while the hand  58  is holding the original  2 . Any arrangement known in the art can be applied to the moving unit  59 . 
     As has been described above, since the original  2  is vacuum-chucked on the holding surface  511  defined by the holding portion  51  in this embodiment, the holding surface  511  is provided with a chuck hole  512 , and the chuck hole  512  communicates with a vacuum source VS via a vacuum flow path  54  (second flow path). An opening/closing valve  61  is provided in the vacuum flow path  54 . By opening the opening/closing valve  61  to exhaust the atmosphere (gas) in the vacuum flow path  54  to the outside by the vacuum source VS, the original  2  can be vacuum-chucked on the holding surface  511  via the chuck hole  512 . 
     Further, in this embodiment, the hand  58  is provided with suction holes  52   a  and  52   b . The suction holes  52   a  and  52   b  communicate with an exhaust source ES via an exhaust flow path  56 . More specifically, the suction hole  52   a  communicates with the exhaust source ES via an exhaust flow path  55   a  (first flow path), and the suction hole  52   b  communicates with the exhaust source ES via an exhaust flow path  55   b  (first flow path). The exhaust flow path  55   a  is a flow path for exhausting the atmosphere around the suction hole  52   a  sucked via the exhaust source ES and the suction hole  52   a  to the outside. The exhaust flow path  55   b  is a flow path for exhausting the atmosphere around the suction hole  52   b  sucked via the exhaust source ES and the suction hole  52   b  to the outside. The exhaust flow paths  55   a  and  55   b  and the vacuum flow path  54  are independent of each other (they form systems different from each other). As shown in  FIGS. 5A and 5C , two suction holes  52   a  and  52   b  are provided in the hand  58  in this embodiment, but the number of the suction holes may be one, or may be three or more. 
     In this embodiment, a switch valve  62  is provided in the exhaust flow path  56  (exhaust flow paths  55   a  and  55   b ). The switch valve  62  functions as a switch mechanism that selectively switches between the communication of the exhaust source ES with the exhaust flow path  55   a  and that with the exhaust flow path  55   b . Note that the switch valve  62  also has a function of simultaneously allowing both the exhaust flow paths  55   a  and  55   b  to communicate with the exhaust source ES, and a function of blocking the communication of the exhaust source ES with both the exhaust flow paths  55   a  and  55   b . The switch valve  62  can be replaced with a simple opening/closing valve. 
     Further, in this embodiment, a counting unit  71  that counts the number of particles contained in the atmosphere to be exhausted to the outside via the exhaust flow path  56  (exhaust flow paths  55   a  and  55   b ) is provided between the switch valve  62  and the exhaust source ES. The counting unit  71  may not include an exhaust source. In addition, the counting unit  71  need not be provided in the lithography apparatus  200 , but may be shared by a plurality of apparatuses. In this case, the counting unit  71  may be provided in the exhaust flow path  56  as needed to count particles. The counting result of the particles obtained by the counting unit  71  is input to a generation unit  83  that has a function of generating a density distribution of particles and a function of specifying a place where particles are generated or flow in. 
     As shown in  FIGS. 5B and 5C , the suction holes  52   a  and  52   b  are provided in a surface different from the holding surface  511 . With this arrangement, it becomes possible to exhaust the atmosphere around the suction holes  52   a  and  52   b  sucked via the exhaust source ES and the suction holes  52   a  and  52   b  to the outside via the exhaust flow path  56  (exhaust flow paths  55   a  and  55   b ) while the hand  58  is holding the original  2  on the holding surface  511 . Note that in this embodiment, the suction holes  52   a  and  52   b  are provided in a side surface  581   c  (third surface) of the base member  581  (that is, they are open along the X-axis direction) as shown in  FIG. 5C . Here, the side surface  581   c  of the base member  581  is a surface orthogonal to a front surface  581   a  (first surface) of the base member  581  on the original  2  side provided with the holding portion  51  and a back surface  581   b  (second surface) opposite to the front surface  581   a . However, the suction holes  52   a  and  52   b  may be provided in the front surface  581   a  of the base member  581 , or may be provided in the back surface  581   b  of the base member  581 . In other words, the suction holes  52   a  and  52   b  need only be provided in at least one of the front surface  581   a , the back surface  581   b , and the side surface  581   c  of the base member  581 . 
     Here, the particle management in the lithography system  100  will be described. As has been described above, as an index of air cleanness, it is customary to numerically indicate how many particles (dust) each having a particle size equal to or larger than 0.5 μm are present in the air per cubic foot. Accordingly, as for an index for counting the number of particles by the counting unit  71 , it is necessary to collect the atmosphere of one cubic foot per minute. When the exhaust pressure of the exhaust source ES is −101.3 kPa (vacuum) with respect to the atmospheric pressure, in order to secure the above-described flow rate while considering the pressure loss, the opening cross-sectional area of each of the suction holes  52   a  and  52   b  is preferably equal to or larger than 4.8 mm 2 . Similarly, the opening cross-sectional area of each of the exhaust flow paths  55   a  and  55   b  is preferably equal to or larger than 4.8 mm 2 . 
       FIG. 6  is a view showing a state in which the conveyance apparatus  50  is counting, in a processing space  520  of the processing unit  210 C of the lithography apparatus  200 , the number of particles contained in the atmosphere in the processing space  520 . A substrate stage SS that holds the substrate  1  conveyed by a conveyance apparatus  10 , and an original stage OS that holds the original  2  conveyed by the conveyance apparatus  50  are provided in the processing unit  210 C. First, in a state in which the switch valve  62  allows both the exhaust flow paths  55   a  and  55   b  to communicate with the exhaust source ES, the counting unit  71  counts the number of particles in the processing space  520  of the processing unit  210 C. Here, if a particle equal to or larger than a standard set in advance, for example, a particle having a particle size equal to or larger than 0.5 μm is counted (detected), the switch valve  62  sets a state in which either one of the exhaust flow paths  55   a  and  55   b  communicates with the exhaust source ES. The reason for allowing either one of the exhaust flow paths  55   a  and  55   b  to communicate with the exhaust source ES is to specify one of the suction holes  52   a  and  52   b  (the position thereof) from which particle are counted. Then, the moving unit  59  moves the hand  58  to each of a plurality of positions in the processing space  520  of the processing unit  210 C. Note that the plurality of positions are set in advance so as to cover (include) the entire processing space  520  of the processing unit  210 C. At this time, the counting unit  71  counts, at each of the plurality of positions in the processing space  520  of the processing unit  210 C, the number of particles contained in the atmosphere around the suction hole  52   a  or  52   b  to be exhausted to the outside via the exhaust flow path  55   a  or  55   b , respectively. The counting result of the particles at each of the plurality of positions in the processing space  520  of the processing unit  210 C (the number of particles at each of the plurality of positions in the processing space  520  of the processing unit  210 C counted by the counting unit  71 ) is input from the counting unit  71  to the generation unit  83 . The generation unit  83  generates the density distribution of particles in the processing space  520  based on the counting result of the particles at each of the plurality of positions in the processing space  520  of the processing unit  210 C, and specifies, from the density distribution, a place where particles are generated or flow in. Note that the generation unit  83  may provide the user with the density distribution of particles in the processing space  520  of the processing unit  210 C via, for example, a display apparatus such as a display. In this case, based on the density distribution of particles provided by the generation unit  83 , the user may specify a place where particles are generated or flow in. The processing as described above is not limited to the processing unit  210 C, and can be performed similarly in the other processing units  210 A,  210 B,  210 D,  210 E, and  210 F. 
       FIG. 7  is a view showing a state in which the conveyance apparatus  50  is counting, in an original conveyance region  530  of the processing unit  210 C of the lithography apparatus  200 , the number of particles contained in the atmosphere in the original conveyance region  530 . First, in a state in which the switch valve  62  allows both the exhaust flow paths  55   a  and  55   b  to communicate with the exhaust source ES, the counting unit  71  counts the number of particles in the entire atmosphere in the original conveyance region  530  of the processing unit  210 C. Here, if a particle equal to or larger than a standard set in advance, for example, a particle having a particle size equal to or larger than 0.5 μm is counted (detected), the switch valve  62  sets a state in which either one of the exhaust flow paths  55   a  and  55   b  communicates with the exhaust source ES. Then, the moving unit  59  moves the hand  58  to each of a plurality of positions in the original conveyance region  530  of the processing unit  210 C. Note that the plurality of positions are set in advance so as to cover (include) the entire original conveyance region  530 . At this time, the counting unit  71  counts, at each of the plurality of positions in the original conveyance region  530 , the number of particles contained in the atmosphere around the suction hole  52   a  or  52   b  to be exhausted to the outside via the exhaust flow path  55   a  or  55   b , respectively. The counting result of the particles at each of the plurality of positions in the original conveyance region  530  of the processing unit  210 C (the number of particles at each of the plurality of positions in the original conveyance region  530  counted by the counting unit  71 ) is input from the counting unit  71  to the generation unit  83 . The generation unit  83  generates the density distribution of particles in the original conveyance region  530  based on the counting result of the particles at each of the plurality of positions in the original conveyance region  530 , and specifies, from the density distribution, a place where particles are generated or flow in. Note that the generation unit  83  may provide the user with the density distribution of particles in the original conveyance region  530  via, for example, a display apparatus such as a display. In this case, based on the density distribution of particles provided by the generation unit  83 , the user may specify a place where particles are generated or flow in. 
     As has been described above, according to this embodiment, since the suction holes  52   a  and  52   b  are provided in the surface different from the holding surface  511 , it is possible to collect particles while the hand  58  is holding the original  2 , that is, during the conveyance of the original  2 . Further, in this embodiment, particles are collected at each of the plurality of positions in the apparatus while allowing either one of the exhaust flow paths  55   a  and  55   b  to communicate with the exhaust source ES, that is, while switching the communication of the exhaust source ES with the exhaust flow path  55   a  and that with the exhaust flow path  55   b . With this arrangement, it becomes possible to generate the density distribution of particles in the apparatus, and it is possible to quickly specify, from the density distribution of particles, a place where particles are generated or flow in. Note that in this embodiment, a new cleaning jig or the like is unnecessary to collect particles. Therefore, this embodiment is advantageous in particle management. 
     A case in which particles are collected during the conveyance of the original  2  has been described in this embodiment, but the present invention is not limited to this. Even in a state in which the hand  58  is not holding the original  2 , for example, even during maintenance or idling of the lithography system  100 , it is possible to collect particles in the apparatus. In other words, this embodiment can constantly collect particles in the apparatus. 
     Third Embodiment 
     An article manufacturing method according to an embodiment of the present invention is suitable for manufacturing an article, for example, a device (a semiconductor device, magnetic storage medium, liquid crystal element, or the like). This manufacturing method includes a step of forming a pattern on a substrate by using the lithography system  100  or the lithography apparatus  200 , a step of processing the substrate on which the pattern has been formed, and a step of manufacturing an article from the processed substrate. This manufacturing method can further includes other known steps (oxidation, deposition, vapor deposition, doping, planarization, etching, resist removal, dicing, bonding, packaging, and the like). The article manufacturing method according to this embodiment is advantageous in at least one of the performance, the quality, the productivity, and the production cost of the article, as compared to a conventional method. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent application No. 2019-219077 filed on Dec. 3, 2019, which is hereby incorporated by reference herein in its entirety.