Patent Publication Number: US-2022223369-A1

Title: Transport Device and Charged Particle Beam System

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-002166, filed Jan. 8, 2021, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a transport device and a charged particle beam system. 
     2. Description of the Related Art 
     In the field of charged particle beam systems including transmission electron microscopes, it is known to use a transport device for conveying a cartridge, which holds a sample therein, into a sample chamber. 
     For example, JP-A-2015-88237 discloses a charged particle beam system equipped with a transport rod for carrying a cartridge between a sample exchange chamber and a sample chamber. The transport rod carries the cartridge into the sample holding portion of a sample holder disposed in the sample chamber. 
     When the cartridge is transferred to the sample holder using the transport rod, a force is applied to the sample holder. This may deform the sample holder, producing drift of the sample. 
     SUMMARY OF THE INVENTION 
     One aspect of the transport device associated with the present invention operates to deliver a cartridge to a sample holder in a charged particle beam system. The transport device includes: a mounting portion to which the cartridge can be detachably mounted; a shaft portion providing support of the mounting portion; a resilient member connecting together the shaft portion and the mounting portion; and a drive mechanism for moving the mounting portion. 
     With this transport device, when the cartridge is delivered to the sample holder, the resilient member deforms resiliently and so the force applied to the sample holder can be reduced. Consequently, drifting of the sample can be reduced. 
     One aspect of the charged particle beam system associated with the present invention includes the sample holder described just above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  are diagrams, partially in block form, showing the configuration of an electron microscope including a transport device associated with one embodiment of the present invention. 
         FIGS. 3 and 4  are schematic plan views, partly in cross section, of the transport device of  FIGS. 1 and 2 , showing different states. 
         FIGS. 5 and 6  are partial cutaway views, illustrating different operational states of the transport device of  FIGS. 1 and 2 . 
         FIGS. 7 and 8  are partial cutaway views, illustrating the functions of a resilient member. 
         FIGS. 9-11  are views illustrating the operation of an electron microscope associated with one embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The preferred embodiments of the present invention are hereinafter described in detail with reference to the accompanying drawings. It is to be understood that the embodiments provided below are not intended to unduly restrict the contents of the present invention delineated by the claims and that not all the configurations set forth below are the essential constituent components of the invention. 
     In the following, an electron microscope using an electron beam is set forth as one example of a charged particle beam system associated with the present invention. The charged particle beam system associated with the present invention may also be an instrument using a charged particle beam other than an electron beam such as an ion beam. 
     1. ELECTRON MICROSCOPE 
     1.1. Configuration of Electron Microscope 
     An electron microscope including a transport device (hereinafter referred to as the second transport device  100 ) associated with one embodiment of the present invention is first described by referring to  FIGS. 1 and 2 , which show the configuration of the electron microscope,  1 , which includes the second transport device  100 .  FIG. 1  is a cross-sectional view taken on line I-I of  FIG. 2 . 
     As shown in  FIG. 1 , the electron microscope  1  includes a sample container  2 , a sample chamber  10 , a sample holder  20 , a sample exchange chamber  30 , a first transport device  40 , vacuum pumping equipment  60 , and a controller  70 , as well as the second transport device  100 . The electron microscope  1  is a transmission electron microscope, for example. 
     The sample chamber  10  is formed in an electron optical column  12 . An electron source for emitting an electron beam, an illumination optical system, and an imaging system (none of which are shown) are housed in the electron optical column  12 . The electron beam emitted from the electron source is directed at a sample by the illumination optical system. The imaging system creates a focused TEM image from the electron beam transmitted through the sample. The electron microscope  1  is also equipped with a detector for detecting the image focused by the imaging system and a detector for detecting X-rays released from the sample in a manner not illustrated. 
     The sample chamber  10  includes the space between top and bottom polepieces of an objective lens (not shown). The sample chamber  10  is evacuated to a vacuum by vacuum pumping equipment. The sample holder  20  has a mounting portion  22  which is disposed in the sample chamber  10 . A cartridge  6  is mounted to the mounting portion  22 . 
     The sample holder  20  is placed in position by a goniometer stage  24  capable of tilting a sample held on the sample holder  20 . In the electron microscope  1 , the sample can be tilted relative to two mutually perpendicular axes, for example. 
     The sample holder  20  has the mounting portion  22  to which the cartridge  6  is mounted as mentioned previously. The sample is held in the cartridge  6 . Because the cartridge  6  is mounted to the mounting portion  22 , the sample can be observed in the electron microscope  1 . 
     The sample exchange chamber  30  is coupled to the sample chamber  10 . A partition valve  32  is mounted between the sample exchange chamber  30  and the sample chamber  10 . 
     The sample container  2  is connected into the sample exchange chamber  30  via a connective member  36  in the illustrated example. The sample container  2  can be mounted to and detached from the connective member  36 . Another partition valve  34  is mounted between the sample exchange chamber  30  and the sample container  2 . The sample exchange chamber  30  and the sample container  2  are evacuated to a vacuum by the vacuum pumping equipment  60 . 
     When the sample container  2  is connected to the connective member  36 , a vacuum seal  38  is placed between the connective member  36  and the sample container  2 . The vacuum seal  38  is an O-ring, for example. When the sample container  2  is coupled into the sample exchange chamber  30 , the vacuum seal  38  makes it possible to make the interiors of the sample exchange chamber  30  and sample container  2  airtight. 
     The sample container  2  is used to receive a sample. In the illustrated example, a magazine  4  is received in the sample container  2 . A plurality of cartridges  6  can be loaded in the magazine  4 . A case is now presented in which the magazine  4  having the cartridges  6  loaded therein is received in the sample container  2 . Alternatively, the cartridges  6  may be directly received into the sample container  2 . 
     The first transport device  40  transports the magazine  4  between the sample container  2  and the sample exchange chamber  30 . The first transport device  40  has a chuck device  42  and a drive mechanism  44  for moving the chuck device  42  in an up/down direction. The chuck device  42  grips the magazine  4 . The drive mechanism  44  moves the chuck device  42  by moving a shaft portion  45  having a front end to which the chuck device  42  is mounted, using power from an electric motor or an air cylinder. 
     The second transport device  100  transports each cartridge  6  between the sample exchange chamber  30  and the sample chamber  10 . The second transport device  100  delivers the cartridge  6  to the sample holder  20 . 
     The second transport device  100  takes out one cartridge  6  from the magazine  4  gripped by the first transport device  40 . The second transport device  100  carries the extracted cartridge  6  from the sample exchange chamber  30  to the sample chamber  10  and mounts the cartridge  6  to the mounting portion  22  of the sample holder  20 . 
     The second transport device  100  has a shaft portion  102 , a chuck device  120 , and a drive mechanism  150  for moving the chuck device  120 . The drive mechanism  150  moves the chuck device  120  horizontally by moving the shaft portion  102  having a front end to which the chuck device  120  is mounted, using power from an electric motor or an air cylinder. 
     As shown in  FIG. 2 , the second transport device  100  mounts the cartridge  6  to the mounting portion  22  of the sample holder  20  by moving the cartridge  6  in an oblique direction C relative to the central axis of the sample holder  20 . 
     The vacuum pumping equipment  60  evacuates the sample container  2  to a vacuum via an exhaust tube  62 . A solenoid valve  64  is mounted in the exhaust tube  62 . The vacuum pumping equipment  60  also evacuates the sample exchange chamber  30  to a vacuum via an exhaust tube  66 . A solenoid valve  68  is mounted in the exhaust tube  66 . The sample exchange chamber  30  is maintained in a vacuum by evacuating the chamber by means of the vacuum pumping equipment  60 . 
     The controller  70  controls the partition valves  32 ,  34 , first transport device  40 , second transport device  100 , and solenoid valves  64 ,  68 . For example, the controller  70  includes a CPU (central processing unit) and storage devices such as a RAM (random access memory) and a ROM (read only memory). The controller  70  performs various kinds of control operations by executing programs stored in the storage devices with the CPU. 
     1.2. Second Transport Device 
       FIGS. 3 and 4  are schematic plan views of the second transport device  100  associated with one embodiment of the present invention.  FIG. 4  shows a state in which the second transport device  100  grips the cartridge  6 , i.e., the cartridge  6  is mounted to the mounting portion  112 . 
     As shown in  FIGS. 3 and 4 , the second transport device  100  includes the shaft portion  102 , the mounting portion  112 , the chuck device  120 , a shaft member  130 , a bearing  132 , and a resilient member  140 . The shaft portion  102  is a rodlike member and supports the mounting portion  112 . The mounting portion  112  can be moved by moving the shaft portion  102  with the drive mechanism  150 . 
     The mounting portion  112  is formed at the front end of the shaft portion  102  and secured to the shaft member  130 . The cartridge  6  can be mounted to the mounting portion  112  which has a cartridge placement surface  114  on which the cartridge  6  is to be placed. 
     The chuck device  120  is mounted to the mounting portion  112  and can secure the cartridge  6  to the mounting portion  112 . The chuck device  120  includes a lever  122  and a manipulative shaft  124 . The lever  122  is mounted to the mounting portion  112  and has a hooked front end portion  121 . This front end portion  121  engages a cutout  8  formed in the cartridge  6 , thus securing the cartridge  6 . The lever  122  has a rear end portion  123  in contact with the manipulative shaft  124 . In the illustrated example, the rear end portion  123  is a ball in contact with the shaft  124 . The lever  122  is biased by a spring (not shown) to press the rear end portion  123  against the manipulative shaft  124 . In the illustrated example, the lever  122  is biased by the spring so as to rotate clockwise. 
     The manipulative shaft  124  is a mechanical member for manipulating the lever  122 . The manipulative shaft  124  has a front end in contact with the lever  122  and movably passes through the shaft member  130  and through the shaft portion  102 . The shaft  124  has a central axis that is parallel, for example, to the central axis L of the shaft portion  102 . The manipulative shaft  124  is connected to a drive source (not shown) such as an air cylinder. Power from the drive source moves the manipulative shaft  124  along the central axis L of the shaft portion  102 , whereby the cartridge  6  can be switched between an unlocked state and a locked state. Details of the operation of the chuck device  120  will be described later. 
     The resilient member  140  connects together the shaft portion  102  and the mounting portion  112 . One end of the resilient member  140  is secured to the shaft member  130 , while the other end is fixed to the shaft portion  102 . 
     In the illustrated example, the shaft portion  102  is provided with a space to receive the resilient member  140  and the manipulative shaft  124 . The space has a larger diameter portion and a smaller diameter portion. The resilient member  140  is received in the larger diameter portion. A protrusive portion  103  is formed at the boundary between the larger and smaller diameter portions and retains the resilient member  140 , which in turn is sandwiched between the shaft member  130  and the protrusive portion  103 . 
     The resilient member  140  is a compression spring, for example. Since the resilient member  140  becomes compressed, it relaxes the compressive force. The resilient member  140  elastically deforms along the central axis L. In the second transport device  100 , the force applied to the sample holder  20  can be reduced by elastic deformation of the resilient member  140  when the cartridge  6  is delivered to the sample holder  20 . 
     The resilient member  140  is not restricted to a spring as long as the force applied to the shaft portion  102  can be reduced by elastic deformation of the resilient member  140 . It may also be a resilient body other than a spring. 
     The mounting portion  112  is connected to the front end of the shaft member  130 . The resilient member  140  is secured to the rear end of the shaft member  130 . In this way, the mounting portion  112  is connected to the shaft portion  102  via the shaft member  130  and the resilient member  140 . The shaft member  130  is cylindrical in form, for example, through which the manipulative shaft  124  passes. 
     The bearing  132  guides rectilinear motion of the shaft member  130 . The bearing  132  and the shaft member  130  together constitute a ball spline, for example. That is, the shaft member  130  is the splined shaft of the ball spline, while the bearing  132  is the outer shell of the ball spline. For example, grooves (splines) are formed in the outer surface of the shaft member  130  along the central axis. Balls (not shown) are retained by a retainer incorporated in the bearing  132  and run in the grooves, thus permitting rectilinear motion of the shaft member  130  while suppressing rotation of the shaft member  130 . 
     The cartridge  6  holds a sample and has a sample stage  7  on which the sample is held. The sample stage  7  is provided with a through hole over which the sample is held. The sample is held on the sample stage  7 , for example, using a C-ring or a leaf spring. The sample stage  7  may be tiltable. The cartridge  6  has the cutout  8  that engages the front end portion  121  of the chuck device  120  as described above. 
     2. OPERATION 
     2.1. Operation of Transport Device 
       FIGS. 5 and 6  illustrate the operation of the second transport device  100 .  FIG. 5  shows a state in which the chuck device  120  locks the cartridge  6  to the mounting portion  112 .  FIG. 6  shows a state in which the chuck device  120  unlocks the cartridge  6 . 
     The manipulative shaft  124  has a first portion  124   a  and a second portion  124   b . The second portion  124   b  is a cutout of the shaft  124 . The first portion  124   a  has no cutout. In the illustrated example, the second portion  124   b  is located closer to the front end of the manipulative shaft  124  than the first portion  124   a.    
     The position at which the rear end portion  123  of the lever  122  contacts the manipulative shaft  124  is varied by moving the shaft  124  along the central axis L of the shaft portion  102 . As a result, the lever  122  can be actuated. 
     When the lever  122  is in contact with the first portion  124   a  as shown in  FIG. 5 , the chuck device  120  holds and clamps the cartridge  6 . In particular, the front end portion  121  of the lever  122  engages the cutout  8  of the cartridge  6 , so that the cartridge  6  is secured to the mounting portion  112 . 
     When the lever  122  is in contact with the second portion  124   b  as shown in  FIG. 6 , the chuck device  120  unlocks the cartridge  6 . In particular, the front end portion  121  of the lever  122  disengages from the cutout  8  of the cartridge  6 , whereby the cartridge  6  is unlocked. 
     If the manipulative shaft  124  is moved in a first direction A from the state where the rear end portion  123  of the lever  122  is in contact with the first portion  124   a  of the shaft  124  as shown in  FIG. 5 , the rear end portion  123  of the lever  122  makes contact with the second portion  124   b . This rotates the lever  122  clockwise and thus the lever  122  disengages from the cutout  8  as shown in  FIG. 6 . As a result, the cartridge  6  is unlocked. 
     Furthermore, if the manipulative shaft  124  is moved in a second direction B from the state where the rear end portion  123  of the lever  122  is in contact with the second portion  124   b  of the manipulative shaft  124  as shown in  FIG. 6 , the rear end portion  123  of the lever  122  makes contact with the first portion  124   a . This rotates the lever  122  counterclockwise, so that the front end portion  121  of the lever  122  engages the cutout  8  as shown in  FIG. 5 . As a result, the cartridge  6  is secured to the mounting portion  112 . 
       FIGS. 7 and 8  illustrate the function of the resilient member  140 .  FIG. 7  shows a state in which the cartridge  6  is secured to the mounting portion  112  by the chuck device  120 .  FIG. 8  shows a state in which the cartridge  6  is unlocked by the chuck device  120 . 
     As shown in  FIG. 7 , the first portion  124   a  of the manipulative shaft  124  has a length of L 1  along the central axis L and the second portion  124   b  has a length of L 2  along the central axis L. The maximum amount of elastic deformation of the resilient member  140  along the central axis L is smaller than the length L 1  of the first portion  124   a  and the length L 2  of the second portion  124   b.    
     Therefore, when the cartridge  6  is secured to the mounting portion  112  by the chuck device shown in  FIG. 5 , if the resilient member  140  elastically deforms, the condition where the cartridge  6  is locked by the chuck device  120  can be maintained as shown in  FIG. 7 . Similarly, when the cartridge  6  is unlocked by the chuck device  120  shown in  FIG. 6 , if the resilient member  140  elastically deforms, the condition where the cartridge  6  is unlocked by the chuck device  120  can be maintained as shown in  FIG. 8 . 
     2.2. OPERATION OF ELECTRON MICROSCOPE 
     2.2.1. Attachment of Cartridge 
     In the electron microscope  1 , the cartridge  6  received in the sample container  2  can be automatically transported into the sample chamber  10  and attached to the mounting portion  112 .  FIGS. 9-11  illustrate the operation of the electron microscope  1 . 
     As shown in  FIG. 9 , the cartridge  6  loaded in the magazine  4  is received in the sample container  2 , which in turn is mounted to the connective member  36 . At this time, the partition valve  34  is closed. The user enters an instruction to the controller  70  to introduce the cartridge  6 . 
     Upon receiving the instruction for introducing the cartridge  6 , the controller  70  opens the solenoid valve  64  and evacuates the interior of the sample container  2  to a vacuum. When the interior of the sample container  2  becomes below a given pressure, the controller  70  opens the partition valve  34 . 
     As shown in  FIG. 10 , the first transport device  40  grips the magazine  4  in the sample container  2  and the magazine  4  is transported into the sample exchange chamber  30  under control of the controller  70 . Then, as shown in  FIG. 11 , the partition valve  34  is closed while the partition valve  32  is opened also under control of the controller  70 . 
     As shown again in  FIG. 1 , the second transport device  100  grips the specified cartridge  6  from within the magazine  4  gripped by the first transport device  40  and transports the gripped cartridge  6  into the sample chamber  10  under control of the controller  70 . At this time, the cartridge  6  is locked by the chuck device  120 . The cartridge  6  passes through the gap between the top and bottom polepieces on its way to the sample chamber  10 . 
     As shown again in  FIG. 2 , the controller  70  causes the second transport device  100  to move the cartridge  6  in an oblique direction C and to deliver the cartridge  6  to the sample holder  20 . In particular, after the second transport device  100  pushes the cartridge  6  into the mounting portion  22  of the sample holder  20 , the chuck device  120  releases the securing of the cartridge  6 . This permits the cartridge  6  to be delivered to the sample holder  20 . 
     When the cartridge  6  is delivered to the sample holder  20 , the cartridge  6  is pushed into the mounting portion  22  of the sample holder  20 . Therefore, a force is applied to the sample holder  20  but elastic deformation of the resilient member  140  of the second transport device  100  can mitigate the force applied to the holder  20 . Consequently, drifting of the sample on the sample holder  20  can be reduced. Furthermore, in the second transport device  100 , if the resilient member  140  elastically deforms, the chuck device  120  can maintain the securing of the cartridge  6 . 
     After delivering the cartridge  6  to the sample holder  20 , the controller  70  returns the chuck device  120  into the sample exchange chamber  30  and closes the partition valve  32 . 
     Because of the processing steps described so far, the cartridge  6  can be delivered to the sample holder  20 . In consequence, the sample held in the cartridge  6  can be observed with the electron microscope  1 . 
     2.2.2. Detachment of Cartridge 
     In the electron microscope  1 , the cartridge  6  can be automatically taken out from the mounting portion  22  of the sample holder  20  and transported into the sample exchange chamber  30 . 
     As shown in  FIG. 1 , the controller  70  opens the partition valve  32  and moves the chuck device  120  of the second transport device  100  into the sample chamber  10 . The chuck device  120  is moved to the mounting portion  22  of the sample holder  20  and locks itself to the mounting portion  22  under control of the controller  70 . The cartridge  6  is moved in a direction reverse to the oblique direction C by the drive mechanism  150  also under control of the controller  70 . Consequently, the cartridge  6  is taken out from the mounting portion  22  of the sample holder  20 . 
     The second transport device  100  transports the cartridge  6  into the sample exchange chamber  30  and then the partition valve  32  is closed under control of the controller  70 . Then, as shown in  FIG. 11 , the second transport device  100  loads the cartridge  6  into the magazine  4  gripped by the first transport device  40  also under control of the controller  70 . Because of the processing steps described so far, the cartridge  6  can be conveyed into the sample exchange chamber  30 . 
     3. FUNCTIONS AND EFFECTS 
     The second transport device  100  includes the mounting portion  112  to which the cartridge  6  can be detachably mounted, the shaft portion  102  providing support of the mounting portion  112 , and the resilient member  140  connecting together the shaft portion  102  and the mounting portion  112 . Therefore, in the second transport device  100 , when the cartridge  6  is delivered to the sample holder  20 , the force applied to the sample holder  20  can be reduced by resilient deformation of the resilient member  140 . This results in less deformation of the sample holder  20 , thus giving rise to less drifting of the sample. 
     The second transport device  100  includes: the shaft member  130  to which the mounting portion  112  is secured; and the bearing  132  for guiding rectilinear motion of the shaft member  130 . The resilient member  140  is connected to the shaft member  130 , while the bearing  132  is secured to the shaft portion  102 . Therefore, in the second transport device  100 , the shaft member  130  to which the mounting portion  112  is secured can be moved rectilinearly. Hence, the force applied to the shaft portion  102  can be reduced efficiently by the resilient member  140 . 
     The second transport device  100  includes the chuck device  120  for locking the cartridge  6  to the mounting portion  112 . The chuck device  120  includes: the lever  122  for securing the cartridge  6 ; and the manipulative shaft  124  connected to the lever  122 . The manipulative shaft  124  moves along the central axis L of the shaft portion  102  to switch between a condition in which the lever  122  locks the cartridge  6  to the mounting portion  112  and a condition in which the lever  122  unlocks the cartridge  6 . Therefore, in the second transport device  100 , the cartridge  6  can be secured to the mounting portion  112 . 
     In the second transport device  100 , the lever  122  secures the cartridge  6  when the lever  122  is in contact with the first portion  124   a  of the manipulative shaft  124 . The lever  122  releases the cartridge  6  when the lever  122  is in contact with the second portion  124   b  of the manipulative shaft  124 . The length L 1  of the first portion  124   a  along the central axis L and the length L 2  of the second portion  124   b  along the central axis L are greater than the maximum amount of elastic deformation of the resilient member  140  along the central axis L. Therefore, when the chuck device  120  secures the cartridge  6  to the mounting portion  112 , if the resilient member  140  elastically deforms, it is possible to maintain the condition where the chuck device  120  locks the cartridge  6 . Similarly, when the chuck device  120  unlocks the cartridge  6 , if the resilient member  140  elastically deforms, it is possible to maintain the condition where the chuck device  120  unlocks the cartridge  6 . 
     4. MODIFIED EMBODIMENTS 
     In the foregoing embodiment, the charged particle beam system associated with the present invention has been described in which an electron microscope for observing or analyzing a sample using an electron beam is taken as an example. The charged particle beam system associated with the present invention may also be an instrument for making an observation or analysis of a sample using a charged particle beam other than an electron beam such as an ion beam. For example, the charged particle beam system associated with the present invention may be a scanning transmission electron microscope, a scanning electron microscope, an Auger electron spectrometer, a focused ion beam system, or the like. 
     It is to be understood that the present invention is not restricted to the above embodiments and modifications and that the invention can be practiced in further modified forms. For example, the present invention embraces configurations substantially identical (e.g., in function, method and results or in purpose and advantageous effects) to the configurations described in the above embodiments. Furthermore, the present invention embraces configurations similar to the configurations described in the above embodiments except that nonessential portions have been replaced. In addition, the present invention embraces configurations identical in advantageous effects or purpose to the configurations described in the above embodiments. Further, the present invention embraces configurations similar to the configurations described in the above embodiments except that a well-known technique is added.