Patent Publication Number: US-8113084-B2

Title: Mounting device

Description:
FIELD OF THE INVENTION 
     The present invention relates to a mounting device having a mounting table for mounting thereon a target object; and, more particularly, to a mounting device having a simplified rotational driving mechanism for rotating a mounting table within a predetermined angle. 
     BACKGROUND OF THE INVENTION 
       FIG. 4  shows an exemplary inspection apparatus having a conventional mounting device. Such an inspection apparatus includes: a mounting device  1 , provided in an inspection chamber, for lifting up and down a target object W (e.g., a semiconductor wafer); an XY stage for moving the mounting device  1  in X and Y directions; a probe card  3  disposed above the XY stage  2 ; and an alignment mechanism  4  for performing alignment between a plurality of probes  3 A of the probe card  3  and the semiconductor wafer W on the mounting device  1 . The inspection apparatus tests electrical characteristics of the semiconductor wafer W by making electrical contacts between the probes  3 A and the semiconductor wafer W which have been aligned. The alignment mechanism  4  further has a lower camera  4 A attached to the mounting device  1  and an upper camera  4 B capable of moving to a position directly under the probe card  3 . 
     As shown in, e.g.,  FIGS. 5A and 5B , the mounting device  1  has a mounting table  1 A for mounting thereon the semiconductor wafer W, an elevation driving mechanism (not shown) for lifting up and down the mounting table  1 A, and a rotational driving mechanism  1 B (hereinafter, referred to as “θ direction driving mechanism”) for rotating the mounting table  1 A within a predetermined angle in a circumferential direction (hereinafter, referred to as “θ direction”). The elevation driving mechanism vertically moves the mounting table  1 A when the semiconductor wafer W needs to be delivered or inspected. The θ direction driving mechanism  1 B rotates the mounting table  1 A, which can be temporarily raised pneumatically, in the θ direction within a predetermined angle, thus performing the alignment between the semiconductor wafer W and the probes  3 A. 
     The θ direction driving mechanism  1 B will be described in more detail with reference to  FIGS. 5A and 5B . As can be seen from  FIGS. 5A and 5B , the θ direction driving mechanism  1 B has a motor  1 C provided near the mounting table  1 A; a ball screw  1 D extending from the motor  1 C in a tangential direction of the mounting table  1 A; a moving body  1 E movably attached to the ball screw  1 D; a protrusion  1 F horizontally protruded from a circumferential surface of the mounting table  1 A; a link  1 G for connecting the moving body  1 E and the protrusion  1 F; and a linear guide mechanism  1 H, provided under the moving body  1 E, for linearly guiding the moving body  1 E. One end portion of the link  1 G is axially supported with respect to a shaft of the moving body  1 E via, e.g., a bearing, and the other end of the link  1 G is axially supported with respect to a shaft of the protrusion  1 F via a linear bush. The shaft of the protrusion  1 F may be a spline shaft. Moreover, a reference numeral  1 I indicates an encoder. 
     If the θ direction driving mechanism  1 B is driven during the alignment between the semiconductor wafer W and the probes  3 A, the moving body  1 E moves linearly along the ball screw  1 D. The linear movement of the moving body  1 E is converted to a rotational movement of the mounting table  1 A via the link  1 G while raising the mounting table  1 A via the linear bush. When the alignment between the semiconductor wafer W and the probes  3  is completed by rotating the mounting table  1 A in a predetermined angle, the motor  1 C stops, and the mounting table  1 A is lowered along the linear bush (or the spline shaft) from the position where the mounting table  1 A was raised and stops. Techniques for pneumatically raising the mounting table  1 A are disclosed in Patent Documents 1 and 2. 
     Patent Document 1: Japanese Patent Laid-open Application No. H07-307368 
     Patent Document 2: Japanese Patent Laid-open Application No. H11-288985 
     However, as shown in  FIGS. 5A and 5B , the conventional θ direction driving mechanism  1 B is constructed by a link mechanism for converting the linear movement of the moving body  1 D to the rotational movement of the mounting table  1 A. Thus, the link mechanism needs to be designed precisely, and efforts are required for installation of the link mechanism, thereby increasing costs therefor. Further, a high-priced linear bush (or spline shaft) is used as the elevation mechanism of the mounting table  1 A, so that the costs increase further. 
     SUMMARY OF THE INVENTION 
     In view of the above, the present invention provides a cost effective mounting device by simplifying a θ direction driving mechanism (a rotational driving mechanism of a mounting table). 
     In accordance with an embodiment of the present invention, there is provided a mounting device including: a vertically movable mounting table for mounting thereon a target object; and a rotational driving mechanism for rotating the mounting table within a predetermined angle. The mounting table is vertically raised and rotated by the rotational driving mechanism. 
     Further, the rotational driving mechanism includes: a driving shaft extending in a tangent direction of the mounting table; a moving body moving in the tangent direction via the driving shaft; a first cam follower attached in perpendicular to the moving body; a second cam follower extending horizontally from an outer circumferential surface of the mounting table so as to be in contact with the first cam follower; and a resilient member for connecting the mounting table and the moving body so as to bring the first cam follower and the second cam follower into elastic contact with each other. 
     Further, the rotational driving mechanism may have a rotation driving unit for rotating the driving shaft. 
     Moreover, the rotational driving mechanism may have a linear guide mechanism for moving and guiding the moving body in the tangent direction. 
     The resilient member may be a spring. 
     In accordance with the embodiment of the present invention, it is possible to provide a cost effective mounting device by employing a simplified rotational driving mechanism of a mounting table. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view showing principal parts of a mounting device in accordance with an embodiment of the present invention; 
         FIG. 2  provides a top view of the mounting device of  FIG. 1 ; 
         FIG. 3  presents a front view of the mounting device of  FIG. 1 ; 
         FIG. 4  represents a front view illustrating an interior of an inspection apparatus in which a conventional mounting device is employed; and 
         FIGS. 5A and 5B  depict principal parts of the mounting device of  FIG. 4 , wherein  FIG. 5A  offers a top view thereof and  FIG. 5B  provides a side view thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT 
     The embodiment of the present invention will be described with reference to  FIGS. 1 to 3  which form a part hereof. 
     As shown in, e.g.,  FIGS. 1 and 2 , the mounting device  10  of this embodiment includes a vertically movable mounting table  11  for mounting thereon a target object (e.g., a semiconductor wafer, not shown) and a rotational driving mechanism (hereinafter, referred to as “θ direction driving mechanism”)  12  for rotating the mounting table  11  within a predetermined angle in a circumferential direction (hereinafter, referred to as “θ direction”). The mounting device  10  of this embodiment is constructed based on the conventional mounting device, except for the θ direction driving mechanism  12 . Hence, hereinafter, the description will focus on the θ direction driving mechanism  12 . 
     As illustrated in  FIGS. 1 and 2 , the θ direction driving mechanism  12  includes: a rotation driving unit (e.g., a motor  121 ) having an encoder and provided near the mounting table  11 ; a driving shaft (e.g., a ball screw  122 ), whose one end is connected with the motor  121 , extending in a tangential direction of the mounting table  11 ; a moving body  123  moving in the tangential direction of the mounting table  11  via the ball screw  122 ; a first cam follower  124 , attached in perpendicular to a top surface of the moving body  123 , rotating about a first shaft  124 A (see  FIG. 2 ); a second cam follower  125  in contact with the first cam follower  124  and rotating about a second shaft  125 A extending horizontally from an outer circumferential surface of the mounting table  11  (see  FIG. 2 ); and a resilient member (e.g., a coil spring  126 ) for connecting the mounting table  11  and the moving body  123  so that the first cam follower  124  and the second cam follower  125  are brought into elastic contact with each other. 
     As can be seen from  FIG. 1 , one end portion of the ball screw  122  is rotatably axially supported by a bearing  122 A. The moving body  123  is screw-coupled with the ball screw  122 . The moving body  123  is constructed to move along the ball screw  122  by the rotation of the motor  121  under the control of the encoder. 
     Moreover, as illustrated in  FIGS. 1 and 2 , the moving body  123  includes a supporting member  123 A extending from an upper part of the moving body  123  toward the motor  121 . The first shaft  124 A is disposed at an extended end portion of the supporting member  123 A, and the first cam follower is rotatably attached to the first shaft  124 A. Further, a first attaching member  127  is fixed to the outer circumferential surface of the mounting table  11  along the circumferential direction thereof. The second shaft  125 A extending horizontally from the outer circumferential surface of the mounting table  11  is fixed to the first attaching member  127 , and the second cam follower  125  is rotatably attached to the second shaft  125 A. 
     A horizontal bracket  127 A is formed at the first attaching member  127  near the second cam follower  125 , and one end of the coil spring  126  is connected to a hole of the bracket  127 A. Moreover, a third shaft  126 A is provided at a base end of the supporting member  123 A, and the other end of the coil spring  126  is connected to the third shaft  126 A. The first cam follower  124  and the second cam follower  125  are brought into elastic contact with each other by the coil spring  126 . 
     In addition, the moving body  123  is constructed to move linearly along the ball screw  122  by the linear guide mechanism  128 , as described in  FIGS. 2 and 3 . The linear guide mechanism  128  has a linear guide  128 A disposed at a position slightly lower than the mounting table  11  and an engagement body  128 B engaged with the linear guide  128 A. A second attaching member  129  is fixedly disposed below a bottom surface of the mounting table  11 , and the linear guide  128 A is attached to the second attaching member  129  in parallel with the ball screw  122 . The engagement body  128 B is fixed to a side surface of the moving body  123 . 
     Accordingly, when the ball screw  122  rotates by the motor  121  and thus the moving body  123  moves linearly along the ball screw  122  by the linear guide mechanism  128 , the mounting table  11  rotates in a state where the first and second cam followers  124  and  125  are in elastic contact with each other by the coil spring  126 . At this time, the mounting table  11  is pneumatically raised in a vertical direction. Since, however, the first and second cam followers  124  and  125  in this embodiment are in elastic contact with each other, the second cam follower  125  is guided by the first cam follower  124  so that the mounting table  11  can be raised in the vertical direction. 
     Hereinafter, an operation will be described. When a semiconductor wafer is mounted on the mounting table  11  and is aligned with a plurality of probes of a probe card, the mounting device  10  is moved in X and Y directions via a XY stage. After completing an alignment of the X and Y directions by an alignment mechanism, the θ direction driving mechanism  12  is driven so that the ball screw  122  is rotated by the motor  121 . Accordingly, the moving body  123  moves linearly along the ball screw  122  by the linear guide mechanism  128  and, simultaneously, the mounting table  11  rotates in a state where the first and second cam followers  124  and  125  are in elastic contact with each other via the coil spring  126 . At this time, the second cam follower  125  is slightly raised along the first cam follower  124 , so that the mounting table  11  is raised vertically. 
     When the alignment between the probes and the semiconductor wafer is completed by raising and rotating the mounting table  11  in a predetermined angle, the motor  121  stops. Then, while the second cam follower  125  is elastically contacting with the first cam follower  124 , the second cam follower  125  is lowered from the position where the mounting table  11  was raised, so that the mounting table  11  is vertically lowered and stops. Therefore, in the present embodiment, the linear movement of the moving body  123  can be converted into the rotational movement of the mounting table  11  by the coil spring  126 . Further, the mounting table  11  can be lifted up and down via the first and the second cam followers  124  and  125 . 
     As set forth above, in accordance with the mounting device  10  of the present embodiment, the θ direction driving mechanism  12  includes: the motor  121 ; the ball screw  122  extending from the motor  121  in the tangential direction of the mounting table  11 ; the moving body  123  moving in the tangential direction by the ball screw  122 ; the first cam follower  124  attached in perpendicular to the moving body  123 ; the second cam follower  125  extending horizontally from the outer circumferential surface of the mounting table  11  so as to be in contact with the first cam follower  124 ; and the coil spring  126  connecting the mounting table  11  and the moving body  123  so that the first and the second cam followers  124  and  125  can be in elastic contact with each other. As described, the coil spring  126  of low cost and simple structure is utilized instead of the conventional link mechanism to convert the linear movement of the moving body  123  into the rotational movement of the mounting table  11 . Moreover, the less costly first and second cam followers  124  and  125  are used to lift the mounting table  11  up and down. Accordingly, in the present embodiment, the θ direction driving mechanism  12  can be constructed at a low cost by simplifying the structure thereof. 
     Further, in accordance with the present embodiment, the θ direction driving mechanism  12  has the linear guide mechanism  128  for moving and guiding the moving body  123  in the tangential direction of the mounting table  11 , thereby enabling to precisely move the moving body  123  linearly along the ball screw  122 . 
     The present invention is not limited to the above embodiment, and the design thereof can be appropriately changed when necessary. In the above embodiment, the coil spring is used as a resilient member for bringing the first and the second cam follower into elastic contact with each other. However, a spring of a different type can be used instead. 
     The present invention can be appropriately used in, e.g., a mounding device of an inspection apparatus. 
     While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.