Patent Publication Number: US-2023133347-A1

Title: Wafer transfer robot apparatus based on direct drive motor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Korean Patent Application No. 10-2021-0146699 (filed on Oct. 29, 2021), which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to wafer transfer robot technology, and more particularly, to a wafer transfer robot apparatus based on a direct drive motor capable of simplify driving parts of the wafer transfer robot and improving overall vibration and precision. 
     As semiconductor technology advances, specifications of a wafer transfer robot required in a semiconductor process have been upgraded. 
     In the existing wafer transfer robot, arms or linkages of the transfer robot are configured in a coaxial manner to enable movement of, for example, three degrees of freedom or more using a plurality of motors. An outermost shaft is coupled to a hub for rotating multiple arms, for example, about a central axis of rotation, and two inner shafts may be connected to each of the multiple arms via independent belt and pulley configurations. 
     In order to mount two hands on the arms of the wafer transfer robot that are used in the past, the arms are lengthened or upper and lower arms are disposed up and down. However, in the case of such a configuration, as the length of the arm increases, the structural rigidity decreases, and thus, the precision of the transfer operation decreases. 
     When the rigidity of the arm increases to improve precision, a weight of the arm increases or a size of the transfer robot increases, which causes difficulties in installation. 
     RELATED ART DOCUMENT 
     Patent Document 
     (Patent Document 0001) Korean Patent No. 10-1382145 (2014.04.01) 
     SUMMARY 
     The present disclosure provides a wafer transfer robot apparatus based on a direct drive motor capable of simplifying driving parts of the wafer transfer robot and improving overall vibration and precision. 
     The present disclosure provides a wafer transfer robot apparatus based on a direct drive motor capable of reducing a weight and volume of R-axis and T-axis driving modules of the wafer transfer robot and reducing costs by using the direct drive motor. 
     The present disclosure provides a wafer transfer robot apparatus based on a direct drive motor capable of minimizing a space for maintaining vacuum by disposing a part of the direct drive motor and an encoder in a vacuum environment and dividing the vacuum and the atmospheric environment with a vacuum blocking thin film. 
     According to embodiments of the present disclosure, a wafer transfer robot apparatus based on a direct drive motor includes: a hand module including a hand loading a wafer from one surface and a hand arm coupled to the hand to transfer the wafer; an R-axis module including a central axis having one end coupled to a hand arm, a rotating motor member coupled along an outer circumference of the central axis, a fixed motor member fixed to the outer circumference of the rotating motor member, and a cylindrical vacuum blocking thin film disposed between the rotating motor member and the fixed motor member to isolate an inside thereof in a vacuum, and providing power to the hand module through the rotating motor member; a connecting enclosing module having one end coupled to the R-axis module; and a T-axis module including a central axis of rotation rotatably coupled to the other end of the connecting enclosure module, a magnetic fluid seal enclosing an outside of the central axis of rotation, and a motor disposed along a lower outer circumference of the central axis of rotation to provide a rotational force to the central axis of rotation. 
     The wafer transfer robot apparatus of claim  1 , wherein the hand module may include: first and second link arms; and an auxiliary central axis coupling one end of the central axis through the first link arm and coupling the hand arm through the second link arm to provide a rotational force of the central axis to the hand arm. 
     The R-axis module may implement the direct drive motor through the rotating motor member and the fixed motor member, and provide the power to the hand module by arranging the plurality of direct drive motors side by side. 
     The R-axis module may include: a rotating side encoder coupled to the other end of the central axis; a fixed side encoder disposed to face the rotating side encoder; and a sheet-type vacuum blocking thin film disposed between the rotating side encoder and the fixed side encoder. 
     The T-axis module may include an enclosure that includes a circular support plate protruding out of a circumference to support the connecting enclosure module and encloses the magnetic fluid seal through the circumference. 
     The T-axis module may include an atmospheric through hole forming an atmosphere inside the central axis of rotation. 
     The T-axis module may extend the atmospheric through hole to a center of the motor, and configure the motor as the direct drive motor with a lower rotating motor member disposed inside the lower outer circumference and a lower fixed motor member disposed outside. 
     The R-axis module and the T-axis module may be driven independently of each other, the T-axis module may operate to rotate the R-axis module to set a direction of the hand, and the R-axis module may operate to perform forward and backward motions of the hand. 
     The disclosed technology can have the following effects. However, since a specific embodiment is not construed as including all of the following effects or only the following effects, it should not be understood that the scope of the disclosed technology is limited to the specific embodiment. 
     According to a wafer transfer robot apparatus based on a direct drive motor according to an embodiment of the present disclosure, it is possible to simplify driving parts of the wafer transfer robot and improve overall vibration and precision. 
     According to a wafer transfer robot apparatus based on a direct drive motor according to an embodiment of the present disclosure, it is possible to reduce a weight and volume of R-axis and T-axis driving modules of the wafer transfer robot and reducing costs by using the direct drive motor. 
     According to a wafer transfer robot apparatus based on a direct drive motor according to an embodiment of the present disclosure, it is possible to minimize a space for maintaining vacuum by disposing a part of the direct drive motor and an encoder in a vacuum environment and dividing the vacuum and the atmospheric environment with a vacuum blocking thin film, thereby saving maintenance costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A and  1 B  are perspective views for describing a wafer transfer robot apparatus based on a direct drive motor according to an embodiment of the present disclosure.  FIG.  1 A  illustrates an appearance of a wafer transfer robot apparatus based on a direct drive motor, and  FIG.  1 B  illustrates a state in which an outer housing is removed from  FIG.  1 A . 
         FIG.  2    is a cross-sectional view for describing the wafer transfer robot apparatus in  FIGS.  1 A and  1 B . 
         FIGS.  3 A to  3 B  are a perspective view and a cross-sectional view for describing an R-axis module in  FIGS.  1 A and  1 B . 
         FIGS.  4 A to  4 B  are a perspective view and a cross-sectional view for describing a T-axis module in  FIGS.  1 A and  1 B . 
         FIG.  5    is a diagram for describing a vacuum environment of the R-axis module in  FIG.  3 B . 
         FIG.  6    is a diagram for describing a vacuum environment of the T-axis module in  FIG.  4 B . 
     
    
    
     DETAILED DESCRIPTION 
     Since the description of the present disclosure is merely an embodiment for structural or functional explanation, the scope of the present disclosure should not be construed as being limited by the embodiments described in the text. That is, since the embodiments may be variously modified and may have various forms, the scope of the present disclosure should be construed as including equivalents capable of realizing the technical idea. In addition, a specific embodiment is not construed as including all the objects or effects presented in the present disclosure or only the effects, and therefore the scope of the present disclosure should not be understood as being limited thereto. 
     On the other hand, the meaning of the terms described in the present application should be understood as follows. 
     Terms such as “first” and “second” are intended to distinguish one component from another component, and the scope of the present disclosure should not be limited by these terms. For example, a first component may be named a second component and the second component may also be similarly named the first component. 
     It is to be understood that when one element is referred to as being “connected to” another element, it may be connected directly to or coupled directly to another element or be connected to another element, having the other element intervening therebetween. On the other hand, it is to be understood that when one element is referred to as being “connected directly to” another element, it may be connected to or coupled to another element without the other element intervening therebetween. Meanwhile, other expressions describing a relationship between components, that is, “between”, “directly between”, “neighboring to”, “directly neighboring to” and the like, should be similarly interpreted. 
     It should be understood that the singular expression include the plural expression unless the context clearly indicates otherwise, and it will be further understood that the terms “comprises” or “have” used in this specification, specify the presence of stated features, steps, operations, components, parts, or a combination thereof, but do not preclude the presence or addition of one or more other features, numerals, steps, operations, components, parts, or a combination thereof. 
     In each step, an identification code (for example, a, b, c, and the like) is used for convenience of description, and the identification code does not describe the order of each step, and each step may be different from the specified order unless the context clearly indicates a particular order. That is, the respective steps may be performed in the same sequence as the described sequence, be performed at substantially the same time, or be performed in an opposite sequence to the described sequence. 
     Unless defined otherwise, all the terms used herein including technical and scientific terms have the same meaning as meanings generally understood by those skilled in the art to which the present disclosure pertains. It should be understood that the terms defined by the dictionary are identical with the meanings within the context of the related art, and they should not be ideally or excessively formally defined unless the context clearly dictates otherwise. 
       FIGS.  1 A and  1 B  are perspective views for describing a wafer transfer robot apparatus based on a direct drive motor according to an embodiment of the present disclosure, and  FIG.  2    is a cross-sectional view for describing the wafer transfer robot apparatus in  FIGS.  1 A and  1 B . 
     Here,  FIG.  1 A  illustrates an appearance of a wafer transfer robot apparatus  100  based on a direct drive motor, and  FIG.  1 B  illustrates a state in which an outer housing is removed from  FIG.  1 A . 
     Referring to  FIGS.  1  and  2   , the wafer transfer robot apparatus  100  based on a direct drive motor may include a hand module  110 , an R-axis module  130 , a connecting enclosure module  150 , and a T-axis module  170 . 
     The hand module  110  includes a hand  111  capable of loading the wafer  200  on one surface, a hand arm  113  coupled to the hand  111  to transport the wafer  200 , and first and second link arms  115  and  117 . 
     The hand arm  113  is disposed on left and right sides of the robot, respectively, and the hand  111  is coupled to one end. The hand  111  may be made of a lightweight metal material such as aluminum (Al) in order to reduce the overall weight while increasing structural rigidity. The hand  111  includes a finger on which the wafer  200  is seated, and the finger may be made of a material that generates little vibration without damaging the wafer  200  due to static electricity. The wafer transfer robot apparatus  100  loads the wafer  200  on the hand  111  and transfers the wafer  200  to a desired position by turning and stretching the hand arm  113 . 
     The first link arm  115  is coupled to a central axis of the R-axis module  130 , and the second link arm  117  is coupled to the other end of the hand arm  113 . The first and second link arms  115  and  117  are connected by a predetermined height difference through an auxiliary central axis  119 . 
     The auxiliary central axis  119  couples one end of the central axis of the R-axis module  130  through the first link arm  115  and the hand arm  113  through the second link arm  117  to provide a rotational force of the central axis of the R-axis module  130  to the hand arm  113 . 
     When the rotational force of the central axis of the R-axis module  130  is provided through the auxiliary central axis  119 , the hand module  110  rotates the second link arm  115 , and thus, is coupled to the second link arm  115  to rotate the hand arm  113 . 
     The R-axis module  130  is an axis for rotating individual link arms, and provides power to the hand module  110 . The existing R-axis module has a structure including a motor, a reducer, and a magnetic fluid seal, but the R-axis module  130  is changed to a structure including a direct drive motor, an encoder, and a vacuum blocking thin film. When the magnetic fluid seal is used, the price of equipment increases because the structure is complicated and expensive magnetic fluid seal should be purchased. In the present disclosure, the R-axis module  130  replaces the magnetic fluid seal with a vacuum blocking thin film to maintain a vacuum state without using the magnetic fluid seal, so that the R-axis module is easy to manage and the price of equipment becomes cheaper than before. 
       FIGS.  3 A to  3 B  are a perspective view and a cross-sectional view for describing the R-axis module in  FIGS.  1 A and  1 B . 
     Referring to  FIGS.  3 A and  3 B , the R-axis module  130  has a central axis  131  having one end coupled to a hand arm  113 , a rotating motor member  132  coupled along an outer circumference of the central axis  131 , a fixed motor member  133  fixed to the outer circumference of the rotating motor member  132 , and a cylindrical vacuum blocking thin film  134  disposed between the rotating motor member  132  and the fixed motor member  133  to isolate the inside in a vacuum. 
     The R-axis module  130  may implement a direct drive motor through the rotating motor member  132  and the fixed motor member  133 . Here, the rotating motor member  132  and the fixed motor member  133  may correspond to the rotating side and the fixed side of the direct drive motor, respectively. The R-axis module  130  may provide power to the hand module  110  by arranging a plurality of direct drive motors side by side. 
     A direct drive (DD) motor refers to a method that directly transmits a rotational force of a motor to a drive target without passing through a mechanism such as a reducer, and may minimize damage caused by friction, such as mechanism and reduce noise by reducing the number of parts that cause contact or vibration. 
     The R-axis module  130  may reduce friction and abrasion occurring in a transmission part by attaching the direct drive motor as the motor member to the central axis  131 . 
     The cylindrical vacuum blocking thin film  134  may be disposed between the rotating motor member  132  and the fixed motor member  133  to isolate the rotating motor member  132  in a vacuum. The R-axis module  130  may divide the rotating motor member  132  and the fixed motor member  133  into a vacuum and an atmospheric environment through the cylindrical vacuum blocking thin film  134 . The R-axis module  130  may provide power to the hand module  110  through the rotating motor member  132  in a vacuum state. 
     The R-axis module  130  has a rotating side encoder  135  coupled to the other end of the central axis  131 , and a fixed side encoder  136  disposed opposite to the rotating side encoder  135 . A sheet-type vacuum blocking thin film  137  is disposed between the rotating side encoder  135  and the fixed side encoder  136 . The sheet-type vacuum blocking thin film  137  may be disposed between the rotating motor member  135  and the fixed motor member  136  to isolate the rotating side encoder  135  in a vacuum. The R-axis module  130  may divide the rotating motor member  135  and the fixed motor member  137  into a vacuum and an atmospheric environment through the sheet-type vacuum blocking thin film  137 . 
     The R-axis module  130  may reduce the weight and volume by maintaining the vacuum state using the vacuum blocking thin films  134  and  137 , and reduce costs compared to using an expensive magnetic fluid seal. The R-axis module  130  may minimize an area maintaining a vacuum state by placing a part of the direct drive motor and the encoder in the vacuum environment and dividing the vacuum and the atmospheric environment with the vacuum blocking thin films  134  and  137 . 
     Returning back to  FIGS.  1  and  2   , the R-axis module  130  has the hand arm  113  through the first and second link arms  115  and  117  coupled to one end thereof and the connecting enclosure module  150  coupled to the other end thereof. 
     One end of the connecting enclosure module  150  is coupled to the R-axis module  130  and the other end thereof is coupled to the T-axis module  170 , so the connecting enclosure module  150  is rotatable by the rotational force provided through the T-axis module  170 . Here, the connecting enclosure module  150  connects the R-axis module  130  and the T-axis module  170 . 
     The T-axis module  170  is an axis for rotating an upper portion of a robot including the R-axis module  130 , and is rotatably coupled to the connecting enclosure module  150 . The existing T-axis module has a structure including a motor, a belt, a pulley, a reducer, and a magnetic fluid seal, but the R-axis module  170  is changed to a structure in which the direct drive motor, the encoder, and the magnetic fluid seal are stacked. 
       FIGS.  4 A to  4 B  are a perspective view and a cross-sectional view for describing the T-axis module in  FIGS.  1 A and  1 B . 
     Referring to  FIGS.  4 A and  4 B , the T-axis module  170  is configured to include a central axis of rotation  171 , a magnetic fluid seal  172 , and a motor  173 . 
     The central axis of rotation  171  rotatably couples the connecting enclosure module  150 . The magnetic fluid seal  172  wraps around the outside of the central axis of rotation  171  and isolates the inside in a vacuum. The motor  173  is disposed along a lower outer circumference  174  of the central axis of rotation  171  to provide the rotational force to the central axis of rotation  171 . Here, the motor  173  is the direct drive (DD) motor, and is configured to include a lower rotating motor member  173   a  disposed inside the lower outer circumference  174  of the central axis of rotation and a lower fixed motor member  173   b  disposed outside. The lower rotating motor member  173   a  and the lower fixed motor member  173   b  may correspond to the rotating side and the fixed side of the direct drive motor, respectively. The T-side module  170  may provide the rotational force to the central axis of rotation  171  by disposing the direct drive motor  173  under the central axis of rotation  171 . 
     The T-axis module  170  includes a lower encoder  175  under the motor  173 . Here, the T-axis module  170  may be configured in the structure in which the lower encoder  175 , the motor  173 , and the magnetic fluid seal  172  are stacked in the order from the bottom to the top to reduce the volume. 
     The T-side module  170  includes a circular support plate  176  protruding out of the circumference to support the connecting enclosure module  150  and an enclosure  177  surrounding the magnetic fluid seal  172  through the circumference. The T-axis module  170  includes an atmospheric through hole  178  that forms an atmosphere inside the central axis of rotation  171 , and the atmospheric through hole  178  extends to the center of the motor  173 . 
     Referring back to  FIGS.  1  and  2   , the R-axis module  130  and the T-axis module  170  are driven independently of each other. The T-axis module  170  operates to set the direction of the hand  111  by rotating the R-axis module  130 . The R-axis module  130  operates to perform the forward and backward motions of the hand  111 . 
       FIG.  5    is a diagram for describing the vacuum environment of the R-axis module in  FIG.  3 B . 
     Referring to  FIG.  5   , the R-axis module  130  may place the vacuum blocking thin films  133  and  137  between the rotating motor member  132  and the fixed motor member  133  coupled along the outer circumference of the central axis  131  and between the rotating side encoder  135  and the fixed side encoder  136  coupled to the end portion of the central axis  131  to isolate the inside in a vacuum. The R-axis module  130  may put the central axis  131 , the rotating motor member  132 , the rotating side encoder  135  disposed inside the vacuum blocking thin films  133  and  137  in the vacuum environment and put the fixed motor member  133  and the fixed side encoder  136  in the atmospheric environment. The R-axis module  130  may divide the vacuum and the atmospheric environment through the vacuum blocking thin films  133  and  137 . 
       FIG.  6    is a diagram for describing the vacuum environment of the T-axis module in  FIG.  4 B . 
     Referring to  FIG.  6   , the T-axis module  170  may dispose the magnetic fluid seal  172  in the form enclosing the outside of the central axis of rotation  171  that rotatably couples the connecting enclosure module  150  to seal the outside of the central axis of rotation  171  in the vacuum state. The T-axis module  170  may form the atmospheric through hole  178  on the inside of the central axis of rotation  171  to maintain the inside of the central axis of rotation  171  in the atmospheric state. The T-axis module  170  has the atmospheric through hole  178  extending to the center of the motor  173  to minimize an area for maintaining a vacuum state by placing the motor  173  and the encoder  175  the atmospheric environment. 
     The wafer transfer robot apparatus based on a direct drive motor according to the embodiment may use the direct drive (DD) motor to simplify parts, reduce vibration, and improve the precision of the transfer operation. 
     The wafer transfer robot apparatus based on a direct drive motor according to the embodiment may use the vacuum blocking thin film on the R-axis and has the structure in which the motor, the encoder, and the magnetic fluid seal are stacked on the T-axis to reduce the overall weight and volume and minimize the space to maintain the vacuum, thereby saving maintenance costs. 
     Although exemplary embodiments of the present disclosure have been disclosed hereinabove, it may be understood by those skilled in the art that the present disclosure may be variously modified and altered without departing from the scope and spirit of the present disclosure described in the following claims.