Patent Publication Number: US-2006006341-A1

Title: Stage apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of Korean Patent Application No. 2004-47051, filed on Jun. 23, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety and by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present general inventive concept relates to a stage apparatus, and more particularly, to a stage apparatus having an improved structure in moving a stage.  
      2. Description of the Related Art  
      Generally, a stage apparatus is used in a scanning apparatus to assist in providing a close examination of a semiconductor wafer, a liquid crystal display (LCD) or the like; a semiconductor processor; a super-precision machine; etc. The stage apparatus is of a linear motion driving mechanism which can drive an object such as the semiconductor wafer to move by a few hundreds of millimeters (mm) to a few nanometers (nm).  
      Such a stage apparatus generally comprises a stage supporting the semiconductor wafer or the like, a slider coupled to the stage and moving together with the stage, a guide to guide the slider, and an actuator provided between the guide and the slider and precisely driving the slider to move.  
      In the conventional stage apparatus, the guide generally penetrates the slider. In more detail, the guide has a rectangular section, and the slider has a guide through hole corresponding to the rectangular section of the guide, so that the guide is inserted in the guide through hole of the slider and supports the slider to be movable. However, because the guide has a structure of being inserted in the slider to guide the slider to move, the conventional stage apparatus has a relatively complicated structure. Further, because both the guide itself and the guide through hole of the slider should be processed to have rectangular section surfaces, production cost is increased. Still further, the guide and the slider are not easily assembled and disassembled.  
     SUMMARY OF THE INVENTION  
      Accordingly, the present general inventive concept provides a stage apparatus which has a relatively simple structure and is easily assembled and disassembled.  
      Additional aspects and advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept.  
      The foregoing and/or other aspects and advantages of the present general inventive concept are achieved by providing a stage apparatus comprising a guide unit having a first guide and a second guide spaced from each other; a movable unit provided between the first guide and the second guide and being movable relative to the guide unit; an air bearing provided between the first guide and the movable unit and coupled to either the first guide or the movable unit; an actuator coupled to one of the movable unit and the second guide and contacting the other one thereof in order to allow the movable unit to be movable relative to the guide unit; and a stage coupled to one of the movable unit and the guide unit and being movable relative to the other one thereof.  
      The actuator may comprise a piezoelectric motor provided in the movable unit and vibrating and pressing the second guide, having an angle larger than a right angle to a surface of the second guide along a moving direction of the movable unit.  
      The actuator may comprise a frictional end part provided in an end of the piezoelectric motor and being contactable with the second guide.  
      One of the movable unit and the first guide may be provided with a protrusion, and the other one thereof may be provided with a protrusion accommodating portion to accommodate the protrusion.  
      At least one of the protrusion and the protrusion accommodating portion may be provided with the air bearing.  
      The protrusion and the protrusion accommodating portion may have triangular sections, respectively.  
      The first guide and the second guide may be disposed in parallel with each other.  
      The second guide may be formed with a contact portion including a material having high surface hardness to contact the actuator.  
      The first guide and the second guide are adjustable in a distance therebetween.  
      The air bearing may be plurally provided and press the movable unit toward the second guide in a direction perpendicular to the surface of the second guide.  
      The stage may be placed above the first guide and the second guide and coupled to the movable unit.  
      The stage may be coupled to the movable unit, leaving the second guide between the stage and the movable unit.  
      The second guide may form a pair of second guides spaced apart from each other, and the actuator may form a pair of actuators in correspondence to the pair of the second guides.  
      The movable unit and the guide unit each may be plurally provided, and the plurality of movable units may be moved relative to the plurality of guide units in the same direction.  
      The movable unit and the guide unit each may be plurally provided, and the plurality of movable units may be coupled to each other to respectively move in different directions so as to move the stage in various directions.  
      The piezoelectric motor may form a pair of piezoelectric motors, and one of the pair of piezoelectric motors may be installed having an angle larger than a right angle to a surface of the second guide along a moving direction of the movable unit, and the other one thereof may be installed having an angle smaller than the right angle to the surface of the second guide along the moving direction of the movable unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompany drawings of which:  
       FIG. 1  is a perspective view of a stage apparatus according to an embodiment of the present general inventive concept;  
       FIG. 2  is a sectional view of the stage apparatus of  FIG. 1 ;  
       FIG. 3  is an exploded perspective view of the stage apparatus of  FIG. 1 ;  
       FIG. 4  is a partial exploded perspective view of an actuator in the stage apparatus of  FIG. 3 ;  
       FIG. 5  is a sectional view of a stage apparatus according to another embodiment of the present general inventive concept;  
       FIG. 6  is a sectional view of a stage apparatus according to yet another embodiment of the present general inventive concept; and  
       FIG. 7  is a perspective view of a stage apparatus according to yet another embodiment of the present general inventive concept. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.  
      As shown in  FIGS. 1 through 4 , a stage apparatus  1  according to an embodiment of the present general inventive concept comprises a guide unit  10  having a first guide member  11  and a second guide member  14  spaced apart from each other; a movable unit  20  provided between the first guide  11  and the second guide  14  and being movable relative to the guide unit  10 ; an actuator  40  coupled to one of the movable unit  20  and the guide unit  10  and contacting the other one in order to allow the movable unit  20  to be movable relative to the guide unit  10 ; and a stage  5  coupled to one of the movable unit  20  and the guide unit  10  and being movable relative to the other one. Further, the stage apparatus  1  according to the present embodiment of the general inventive concept comprises an air bearing  30  placed between the first guide member  11  and the movable unit  20  and provided in at least one of the first guide member  11  and the movable unit  20 . Further, the stage apparatus  1  according to the present embodiment comprises a position measuring unit (not shown) to measure a moved distance of the movable unit  20  relative to the guide unit  10 .  
      The stage  5  may be shaped like a plate to support an object such as a semiconductor wafer, an LCD panel or the like. The stage  5  moves straightly with precision enough to have an error of 100 nm with respect to a moving distance by a few hundreds of millimeters. However, the stage may move straightly with precision enough to have an error of 100 nm or less with respect to a moving distance by a few hundreds of millimeters or more. According to the present embodiment, the stage  5  is coupled to the movable unit  20  by a stage supporter  6  and moves integrally with the movable unit  20  relative to the guide unit  10 . The stage  5  is placed above the first guide member  11  and the second guide member  14  and coupled to the movable unit  20 . However, the stage may be coupled to the guide unit  10  and may move relative to the movable unit  20 .  
      The guide unit  10  supports the movable unit  20  to move relative to the guide unit  10 . The guide unit  10  further comprises a guide base  17  supporting the first guide member  11  and the second guide member  14  which are spaced from each other.  
      The first guide member  11  may be shaped like a long block having a rectangular section. However, the first guide member  11  may have various sections such as a triangular section, a circular section, etc. Further, the first guide member  11  may be formed with a protrusion accommodating portion  12  to accommodate a protrusion  21  of the movable unit  20  (to be described later). However, the first guide  11  may be formed with the protrusion  21  and the movable unit  20  may be formed with the protrusion accommodating portion  12 .  
      The protrusion accommodating portion  12  may have a triangular section. However, the protrusion accommodating portion  12  may have various sections such as a rectangular section, a semicircular section, etc., corresponding to the shape of the protrusion  21 . Here, a distance between the first guide member  11  and the second guide member  14  can be adjustable.  
      The second guide member  14  can have a block shape having a rectangular section like the first guide member  11 . However, the second guide member  14  may have various shaped sections, such as a triangular section or other polygonal type shaped section. The second guide member  14  can be disposed in parallel with the first guide member  11 . That is, the second guide member  14  is coupled to the guide base  17  to be parallel with the first guide member  11 . Further, the second guide member  14  is provided with a contact portion  15  to contact the actuator  40 .  
      The contact portion  15  is precisely manufactured with a material having high surface hardness. That is, the contact portion  15  is in contact with a frictional end  43  of the actuator  40  (to be described later) to drive the movable unit  20  to move, so that the contact portion  15  is made of a metal material, a ceramic material, or the like which has a high surface hardness and is not easily deformed due to making contact.  
      The guide base  17  is shaped like a plate and supports the first guide member  11  and the second guide member  14  to be spaced apart from each other. Here, the guide base  17  allows a distance between the first guide member  11  and the second guide member  14  coupled thereto to be adjustable. That is, the guide base  17  may be coupled to the first guide member  11  and the second guide member  14  by a fastening bolt  19 . Alternatively, another type fastening device that performs the intended purpose described above may be used. Further, the guide base  17  may comprise a fastening hole  18   a  to be coupled with one of the first guide member  11  and the second guide member  14  by the fastening bolt  19 , and an elongated hole  18   b  to be coupled with the other one by the fastening bolt  19 . Thus, one of the first guide member  11  and the second guide member  14  is movable through the elongated hole  18   b,  thereby adjusting the distance between the first guide member  11  and the second guide member  14 .  
      The movable unit  20  is provided between the first guide member  11  and the second guide member  14  and may have a block shape. The movable unit  20  is provided with the protrusion  21  protruding in correspondence to the protrusion accommodating portion  12  of the first guide member  11 . The movable unit  20  comprises the air bearing  30  provided in a first side thereof facing the first guide member  11  and the actuator  40  provided in a second side thereof facing the second guide member  14 . The movable unit  20  may be provided with an air supply (not shown) to supply compressed air to the air bearing  30 .  
      The protrusion  21  has a triangular section corresponding to the shape of the protrusion accommodating portion  12 , but may have various sections corresponding to the shape of the protrusion accommodating portion  12 .  
      According to the present embodiment, a plurality of air bearings  30  may be provided in the movable unit  20 . Each of the air bearing(s)  30  blows compressed air toward the first guide member  11  to levitate the movable unit  20  from the first guide  11 , thereby preventing friction between the movable unit  20  and the first guide  11  while the movable unit  20  moves. However, the air bearing  30  may be one in number, and may be placed in the first guide member  11  instead of in the movable unit  20 . For example, the plurality of air bearings  30 , when provided in plural, are placed in the protrusion  21  of the movable unit  20 . However, the air bearings  30  may be placed in the protrusion accommodating portion  12  of the first guide member  11 . Here, the air bearings would  30  urge the movable unit  20  in a direction perpendicular to a surface of the second guide member  14 . That is, the plurality of the air bearings  30  press the movable unit  20  toward the second guide member  14  in a direction perpendicular to the surface of the second guide member  14 . Thus, each air bearing  30  is supplied with air having a predetermined pressure, so that it is possible to adjust a preload of the actuator  40  initially being in contact with the second guide member  14 .  
      The actuator  40  may be provided in the movable unit  20 . However, the actuator  40  may alternatively be provided in the second guide member  14 . The actuator  40  comprises a piezoelectric motor  41  periodically vibrating and pressing the second guide member  14 , having an angle larger than a right angle to the surface of the second guide member  14  in a moving direction of the movable unit  20 . Further, the actuator  40  comprises a frictional end  43  provided at an end of the piezoelectric motor  41  and being contactable with the second guide member  14 .  
      The piezoelectric motor  41  operates based on a principle that a piezoelectric vibrator vibrates by alternating current, and transforms vibrating motion into straight motion by slantingly contacting a facing surface in a right angle direction to the facing surface. Further, the piezoelectric motor  41  can be connected with an amplifier (not shown) to amplify the alternating current supplied to the piezoelectric motor  41  or adjust the frequency of the alternating current.  
      The piezoelectric motor  41  vibrates and presses the second guide member  14  in the moving direction of the movable unit  20 , having an angle larger than the right angle to the surface of the second guide  14 . As shown in  FIG. 4 , a pressing direction “A” of the piezoelectric motor  41  forms an inside angle “C” with respect to the right angle “B” to the contact portion  15 . Such an inside angle “C” is formed along a moving direction “D” of the movable unit  20 . The larger the inside angle “C” is, the faster the movable unit  20  moves, wherein the moving speed of the movable unit  20  is preferably adjusted in consideration of precision. Such an inside angle is preferably of 1° through 10°, but may be of 10° or more. Thus, the piezoelectric motor  41  can drive the movable unit  20  to move relative to the guide unit  10  in the moving direction “D.” Here, the piezoelectric motor  41  may form at least one pair of motors. That is, one of the pair of piezoelectric motors  41  can be installed having an angle larger than the right angle to the surface of the second guide member  14  along the moving direction “D” of the movable unit  20 , and the other one of the motors  41  can be installed having an angle smaller than the right angle to the surface of the second guide member  14  along the moving direction “D” of the movable unit  20 . Thus, the pair of piezoelectric motor  41  can drive the movable unit  20  to move in the moving direction “D” or in an opposite direction to the moving direction “D.” 
      The frictional end  43  of the actuator  40  has a first end coupled to the piezoelectric motor  41  and a second end tapered to be in contact with the second guide member  14 . The frictional end  43  of the actuator  40  can have a triangular section and can include the first end coupled to the piezoelectric motor  41  and the second end having a vertex to contact the contact portion  15  of the second guide  14  due to the vibration of the piezoelectric motor  41 . The frictional end  43  of the actuator  40  is precisely made of a high stiffness material. That is, the frictional end  43  is made of a metal material, a ceramic material, etc. having high stiffness. Thus, the frictional end  43  of the actuator  40  is in contact with the contact portion  15  due to the vibration of the piezoelectric motor  41 , thereby moving the movable unit  20  in the moving direction.  
      With this configuration, the stage apparatus  1  according to the present embodiment of the present general inventive concept can be assembled and operated as follows.  
      In an assembling process of the stage apparatus  1 , the movable unit  20  provided with the air bearing  30  and the actuator  40  is placed between the first guide member  11  and the second guide member  14 . Then, the first guide member  11  and the second guide member  14  are fastened to the guide base  17 , properly adjusting the distance therebetween. On the other hand, a disassembling process of the stage apparatus  1  is performed in just a reverse order, and therefore detailed descriptions of this process will be omitted.  
      In an operating process of the stage apparatus  1 , the air pressure is properly adjusted to support the preload of the actuator  40  and then the air is supplied to the air bearing  30 , thereby allowing the actuator  40  to press the second guide member  14 . Then, the piezoelectric motor  41  of the actuator  40  is turned on to vibrate. Then, the frictional end  43  coupled to the piezoelectric motor  41  repetitively contacts the contact portion  15  coupled to the second guide member  14 , thereby moving the movable unit  20 . Thus, the stage  5  coupled to the movable unit  20  is moved relative to the guide unit  10 .  
      As described above, in the stage apparatus  1  according to present embodiment, the movable unit  20  is supported between the first guide member  11  and the second guide member  14 , so that the stage apparatus  1  has a simple structure and is easily assembled and disassembled. Further, in the stage apparatus  1  according to the present embodiment, the air bearing  30  is supplied with air by the proper air pressure, thereby easily adjusting the preload of the actuator  40  pressing the second guide member  14 .  
       FIG. 5  is a sectional view of a stage apparatus according to another embodiment of the present general inventive concept. As shown therein, a stage apparatus  101  according to the present embodiment is different in an installation position of a stage  105  from that of the previous embodiment.  
      The stage  105  is coupled to a movable unit  120 , leaving a second guide member  114  of a guide unit  110  between the stage  105  and the movable unit  120 . As shown in  FIG. 5 , a pair of second guide members  114  are spaced from each other and disposed above a first guide member  111 . The movable unit  120  is provided between the first guide member  111  and the second guide member  114 . The stage  105  is disposed above the second guide  114 . The stage  105  is coupled to the movable unit  120  with a stage supporter  106  provided between the pair of second guide members  114 , thereby moving integrally with the movable unit  120  relative to the guide unit  110 .  
      At least one side of opposite sides of both the first guide member  111  and the second guide member  114  is coupled with a guide supporter  117  by a fastening bolt  19 . A protrusion accommodating portion  112  is formed on the first guide member  111 , and a protrusion  121  is provided under the second guide member  114 . The bottom of each second guide member  114  is provided with a contact portion  15  to be in contact with a frictional end  43  of an actuator  40 . Here, the actuator  40  is provided on the movable unit  120  and forms a pair of actuators  40  in correspondence to the pair of second guide members  114 .  
      With this configuration, in the stage apparatus  101  according to this embodiment, air of proper pressure is supplied to an air bearing  130  coupled to the movable unit  120  to support preload of the actuator  40 , and the piezoelectric motors  41  of the actuator  40  are turned on to move the movable unit  120  relative to the guide unit  110 .  
      Further, in the stage apparatus  101  according to the embodiment of  FIG. 5 , when the stage apparatus  101  does not operate and stops supplying air, the protrusion  121  of the movable unit  120  is landed in balance on the protrusion accommodating portion  112  of the first guide  111  by its own weight. Therefore, the precision and the life span thereof are improved and prolonged. Further, like that of the previous embodiment, the stage apparatus  101  according to the embodiment of  FIG. 5  has simple configurations, can easily adjust the preload of the actuator  40 , and is easily assembled and disassembled.  
       FIG. 6  is a sectional view of a stage apparatus according to another embodiment of the present general inventive concept. As shown therein, a stage apparatus  201  according to this embodiment comprises a plurality of movable units  20 , and a plurality of guide units  10 , differently from that of the embodiment of  FIGS. 1-4 , wherein the plurality of movable units  20  moves relative to the plurality of the guide units  10  in the same direction.  
      For example, a pair of guide units  10  and a pair of movable units  20  are provided to be coupled with opposite ends of a stage  205 . However, two pairs or more of guide units  10  and two pairs or more of movable units  20  may be provided to be coupled with the stage  205 . Further, the pair of movable units  20  is coupled to the stage  205  and moves together with the stage  205 . However, the pair of guide units  10  may be coupled with the stage  205 .  
      Each guide unit  10  comprises the first guide member  11  and the second guide member  14 , and the movable unit  20  coupled with the air bearing  30  and the actuator  40  are configured like those of the embodiment of  FIGS. 1-4 , so that detailed descriptions thereof will be omitted. However, the guide units  10  and the movable units  20  according to the present embodiment may be configured like those of the previous embodiment of  FIG. 5 .  
      With this configuration, in the stage apparatus  201  according to the present embodiment, the stage  205  and the movable units  20  can be moved relative to the guide units  10 .  
      Further, in the stage apparatus  201  according to the present embodiment, the movable units  20  and the guide units  10  are plurally provided to support the stage  205 , thereby more precisely moving the stage  205 . Further, like that of the embodiment of  FIGS. 1-4 , the stage apparatus  201  according to the present embodiment of  FIG. 6  has simple configurations, can easily adjust the preload of the actuator  40 , and is easily assembled and disassembled.  
       FIG. 7  is a perspective view of a stage apparatus according to another embodiment of the present general inventive concept. As shown therein, a stage apparatus  301  according to the present embodiment comprises a plurality of movable units  20   a  and  20   b,  and a plurality of guide units  10   a  and  10   b,  provided differently from that of the  FIGS. 1-4  embodiment, wherein the plurality of movable units  20   a  and  20   b  moves relative to the plurality of the guide units  10  in different directions, respectively.  
      For example, the guide units  10   a  and  10   b  and the movable units  20   a  and  20   b  are piled up. That is, a second stage apparatus  301   b  is piled up on a first stage apparatus  301   a  (the same as disclosed in the embodiment of  FIGS. 1-4 ). Further, the first movable unit  20   a  and the second movable unit  20   b  are moved in different directions, for example, in a direction having a right angle to each other. Also, the first guide unit  10   a  and the second guide unit  10   b  are installed along different directions corresponding to the first movable unit  20   a  and the second movable unit  20   b.  Thus, the stage  305  coupled to the second movable unit  20   b  can move in various directions.  
      With this configuration, in the stage apparatus  301  according to the fourth embodiment of  FIG. 7 , the stage  305  and the movable unit  20   b  can be moved relative to the first and second guide units  10   a  and  10   b,  respectively.  
      Further, in the stage apparatus  301  according to  FIG. 7 , the stage  305  can move in various directions. Further, like that of the embodiment of  FIGS. 1-4 , the stage apparatus  301  according to the present embodiment has simple configurations, can easily adjust the preload of the actuator  40 , and is easily assembled and disassembled.  
      As described above, the present general inventive concept provides a stage apparatus having a simple structure and being easily assembled and disassembled.  
      Further, the present general inventive concept provides a stage apparatus in which preload of an actuator is easily adjusted by supplying air of proper pressure.  
      Although various embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.