Abstract:
A positioning method that includes a step of moving a stage apparatus for supporting a workpiece or an object to be measured from an auxiliary mount to a positioning mount using a rolling guide extending from the positioning mount onto the auxiliary mount, a step of lifting the stage apparatus moved to the positioning mount using a lifting unit to extract the rolling guide, and a step of lowering the stage apparatus onto the positioning mount, from which the rolling guide is extracted, to cause the stage apparatus to abut a reference member and to position the stage apparatus, while hydrostatically supporting the stage apparatus by a hydrostatic bearing unit. A positioning apparatus for performing a positioning method is also set forth.

Description:
[0001]     This application claims priority from Japanese Patent Application No. 2003-200197 filed Jul. 23, 2003, which is hereby incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a positioning method and a positioning apparatus, which are capable of quickly and precisely positioning or aligning even a very heavy stage apparatus for supporting a wafer, a mask, an object to be measured (e.g., a measurement object), or the like, in assemblages of a semiconductor exposure apparatus, an electron-beam drawing apparatus, a precise measuring instrument, and the like.  
         [0004]     2. Description of the Related Art  
         [0005]     In assemblages of an exposure apparatus for producing a semiconductor, an electron-beam drawing apparatus, a precise measuring instrument, and the like, it is required that the stage apparatus for supporting a wafer, a mask, a measurement object, or the like, be quickly and precisely positioned relative to an exposure optical system, and the like. There has been proposed a conventional positioning apparatus for performing, for example, pre-alignment of a substrate, such as a glass plate, which is to be mounted on a semiconductor exposure apparatus, an exposure apparatus for producing a liquid crystal display device, and the like, a working apparatus, or an inspection apparatus, as disclosed in Japanese Patent Application Laid-Open No. 5-109871 (1993). In such a disclosed positioning apparatus, which is illustrated in  FIG. 9  of this application, when pre-alignment is executed by pressing a substrate P on a holder  103  against reference rollers  104 A,  104 B and  104 C using two pressing rollers  104 D and  104 E for providing forces in two directions, respectively, pressing forces generated by the pressing rollers  104 D and  104 E at the time of positioning are made small, and a sensor  125  for generating a positioning-completion signal is used in order to prevent an occurrence of mechanical distortion (deformation) of the substrate P.  
         [0006]     Further, Japanese Patent Application Laid-Open No. 7-308834 (1995) discloses, as illustrated in  FIG. 10  of this application, a moving table in which guide rails  212   a  to  212   d  are fixed to a movable mount  218  and a stationary base  219 , respectively, and the movable mount  218  is movably supported on balls  211 .  
         [0007]     However, the positioning apparatuses discussed above are to be used for positioning a relatively-light substrate, and it is, hence, difficult to adapt these apparatuses to the positioning of a heavy stage apparatus. More specifically, if a heavy body is moved on the holder by the pressing rollers in the apparatus shown in  FIG. 9 , there is a danger that its installation surface is rubbed and becomes damaged. Furthermore, since the frictional resistance is large, it is difficult to accurately press the body against the three reference rollers, so that a partially-butting condition is likely to occur.  
         [0008]     In the latter apparatus, as shown in  FIG. 10 , and assuming that the movable mount is a heavy body to be positioned, its rigidity is low because the body is supported by the balls even after the positioning. Accordingly, the apparatus cannot be applied to highly-precise positioning.  
       SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to provide a positioning method and a positioning apparatus, which are capable of quickly, safely and highly precisely positioning or aligning even a very heavy stage apparatus relative to a base, on which the stage apparatus is to be installed, in assemblages of a body of apparatuses, such as an exposure apparatus, an electron-beam drawing apparatus, and a precise measuring instrument.  
         [0010]     According to one aspect, the present invention provides a positioning method, which includes a step of moving a stage apparatus for supporting a workpiece or an object to be measured from an auxiliary mount to a positioning mount using a rolling guide extending from the positioning mount onto the auxiliary mount, a step of lifting the stage apparatus moved to the positioning mount using a lifting unit to extract the rolling guide, and a step of lowering the stage apparatus onto the positioning mount, from which the rolling guide is extracted, to cause the stage apparatus to abut a reference member and to position the stage apparatus, while hydrostatically supporting the stage apparatus by a hydrostatic bearing unit.  
         [0011]     According to another aspect, the present invention provides a positioning apparatus, which includes a positioning mount with a reference member and a supporting surface for positioning a stage apparatus for supporting a workpiece or an object to be measured, an auxiliary mount with a movement surface forming an extension portion of the supporting surface of the positioning mount, a rolling guide for movably supporting the stage apparatus on the supporting surface and the movement surface, a hydrostatic bearing unit for establishing a non-contact relationship between the stage apparatus and the supporting surface, and a lifting unit for lifting the stage apparatus from the supporting surface. The rolling guide may further include a lower-side guide plate provided on the supporting surface and the movement surface in a detachably attachable manner, an upper-side guide plate provided on a bottom surface of the stage apparatus in a detachably attachable manner, and a plurality of rollers rotatably held between the lower-side guide plate and the upper-side guide plate.  
         [0012]     The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1A  is a plan view illustrating a first embodiment of a positioning apparatus according to the present invention;  
         [0014]      FIG. 1B  is an elevational view taken from a line  1 B- 1 B of  FIG. 1A ;  
         [0015]      FIG. 2  is a cross-sectional view illustrating the apparatus of  FIGS. 1A and 1B ;  
         [0016]      FIG. 3  is a view illustrating a lifting unit for lifting a stage apparatus from a positioning mount;  
         [0017]      FIG. 4  is a view illustrating another lifting unit for lifting the stage apparatus from the positioning mount;  
         [0018]      FIG. 5A  is a plan view illustrating a state in which the stage apparatus is positioned on the positioning mount with respect to X and Y directions;  
         [0019]      FIG. 5B  is an elevational view of the apparatus shown in  FIG. 5A ;  
         [0020]      FIG. 6  is a cross-sectional view illustrating the apparatus of  FIGS. 5A and 5B ;  
         [0021]      FIG. 7A  is a plan view illustrating a second embodiment of a positioning apparatus according to the present invention;  
         [0022]      FIG. 7B  is an elevational view of the apparatus shown in  FIG. 7A ;  
         [0023]      FIG. 8A  is a plan view illustrating a modification of the second embodiment;  
         [0024]      FIG. 8B  is an elevational view of the apparatus shown in  FIG. 8A ;  
         [0025]      FIG. 9  is a view illustrating a conventional apparatus; and  
         [0026]      FIG. 10  is a view illustrating another conventional apparatus. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]     Preferred embodiments of the present invention will hereinafter be described with reference to the accompanying drawings.  
         [0028]     A first embodiment of the present invention will be described with reference to  FIGS. 1A and 1B . The first embodiment is directed to a positioning apparatus constituting a positioning body portion of an exposure apparatus, an electron-beam drawing apparatus, a precise measuring instrument, or the like. On a base  1  serving as a stationary base, there are arranged a positioning mount  3  for positioning a stage apparatus  2  for supporting a substrate, such as a wafer, which is a workpiece or a measurement object, and a pair of guides  4  serving as a rolling guide interposed between the stage apparatus  2  and the positioning mount  3  in a detachably attachable manner. Each guide  4  includes a plurality of rollers  41  serving as a rolling member, a plate-like retainer  42  with holes for holding the rollers  41 , a lower-side guide plate  43  in contact with (abutting) lower sides of the rollers  41 , and an upper-side guide plate  44  in contact with (abutting) upper sides of the rollers  41 . The upper-side guide plate  44  fits into a guide groove  2   a  formed on a lower surface of the stage apparatus  2  in a detachably attachable manner, and the lower-side guide plate  43  fits into a guide groove  3   a  formed on an upper surface of the positioning mount  3  in a detachably attachable manner.  
         [0029]     On the positioning mount  3 , are provided, in a stand-up fashion, reference members  31  to  33  for positioning the stage apparatus  2  in the X and Y directions, respectively. A bottom surface of the stage apparatus  2  constitutes a reference surface that can be freely brought into contact (abutment) with a supporting surface (an upper surface) of the positioning mount  3 .  
         [0030]     The stage apparatus  2  is provided with hydrostatic bearings  5  serving as a hydrostatic bearing unit that faces the upper surface of the positioning mount  3 . In the event that the stage apparatus  2  is positioned while being in contact (abutment) with the reference members  31  to  33  (as discussed later) after each guide  4  is extracted while the stage apparatus  2  is lifted from the base  1 , the stage apparatus  2  is floated from the positioning mount  3  by the hydrostatic bearings  5 .  
         [0031]     As illustrated in  FIG. 2 , a detachably-attachable auxiliary base  6  is in contact (abutment) with an end surface of the base  1 , an auxiliary mount  7  is installed on the auxiliary base  6 , and an upper surface of the auxiliary mount  7  constitutes a movement surface that is an extension portion from the supporting surface of the positioning mount  3 . The lower-side guide plate  43  extends from the guide groove  3   a  ( FIG. 1B ) of the positioning mount  3  into a guide groove  7   a  ( FIG. 1A ) formed on the auxiliary mount  7 , and is capable of lightly moving the stage apparatus  2  installed on the auxiliary mount  7  up to the positioning mount  3  on the base  1  by means of rolling motions of the rollers  41 . In this event, the guide  4  moves by an around L/2 while the stage apparatus  2  moves by a movement amount L. Accordingly, the minimum necessary length of the guide  4  is equal to or more than a value of the length of the stage apparatus  2  plus the movement amount L/2.  
         [0032]     Further, the height and inclination of the auxiliary mount  7  are so adjusted as to be approximately equal to those of the positioning mount  3 . The upper-side guide plate  44  moves together with the stage apparatus  2 , and the lower-side guide plate  43  extends over an almost overall length of the positioning mount  3  and the auxiliary mount  7  so as to cover a connection portion therebetween. Since the lower-side guide plate  43  covers the connection portion between the positioning mount  3  and the auxiliary mount  7 , the roller  41  can pass the connection portion without any engagement, even if there is a step or an inclination at the connection portion.  
         [0033]     Under a condition in which the stage apparatus  2  is moved to a place near the reference members  32  and  33  of the positioning mount  3 , as illustrated in  FIG. 3 , the stage apparatus  2  is lifted by a screw  11  serving as a lifting unit penetrating a screw block  10  of the stage apparatus  2 , and the stage apparatus  2  is settled on the positioning mount  3  by retracting the screw  11  again after both the guides  4  are extracted and the auxiliary mount  7  and the auxiliary base  6  are detached. Here, the upper-side and lower-side guide plates  43  and  44  can be extracted together with the guides  4 .  
         [0034]     Then, upon supply of compressed air to the hydrostatic bearings  5  through a pipe (not shown), the compressed air is injected toward the positioning mount  3 , and the stage apparatus  2  is caused to float from the positioning mount  3  and supported by the hydrostatic pressure in a non-contact fashion. Under this condition, the stage apparatus  2  is moved in the X and Y directions, and brought into contact (abutment) with the individual reference members  31  to  33 . Thus, the positioning of the stage apparatus  2  is performed as illustrated in  FIGS. 5A and 5B .  
         [0035]     Because the stage apparatus  2  is caused to float by the hydrostatic bearing  5 , no stick-slip motion occurs, and the stage apparatus  2  can be brought into contact (abutment) with the reference members  31  to  33  and positioned very lightly, accurately and quickly by using only a small force.  
         [0036]     In place of the screw  11  for lifting the positioning mount  3  from the stage apparatus  2 , a cylinder mechanism serving as a lifting unit can be used, as illustrated in  FIG. 4 . This cylinder mechanism includes a cylinder  20  buried in the base  1  and a piston  21  that is to be brought into contact (abutment) with the lower surface of the stage apparatus  2  to lift the stage apparatus  2 .  
         [0037]      FIGS. 5A, 5B  and  6  are, respectively, a plan view, an elevation and a cross-sectional view showing a positioning-completed state in which the stage apparatus  2  is positioned with respect to the X and Y directions, and brought into contact (abutment) with the reference members  31  to  33 .  
         [0038]     In general, a high precision measuring instrument, a semiconductor exposure apparatus, and the like, are disposed in a thermostatic chamber or a vacuum chamber. In the event that the auxiliary mount  7  is so constructed as to extend outside such a chamber, it is possible to use a conveying apparatus, such as a crane, during an operation for installing the stage apparatus  2  on the auxiliary mount  7 . The assemblage operating efficiency of a semiconductor exposure apparatus, an electron-beam drawing apparatus, and the like, can be improved, and the maintenance cost thereof can also be reduced by the use of the positioning apparatus discussed above.  
         [0039]     A second embodiment of the present invention will be described with reference to  FIGS. 7A and 7B . In the second embodiment, three spacers  34  serving as a supporting member are interposed between the above-discussed positioning mount 3 and base  1 . The three spacers  34  are arranged approximately equiangularly about a center of gravity of the stage apparatus  2  and the positioning mount  3  to support the positioning mount  3  at three points.  
         [0040]     Further, each hydrostatic bearing  5  is arranged at a location of each spacer  34  in a superimposing manner. Since the positioning mount  3  is thus supported at three points, the stage apparatus  2  is likewise supported substantially at three points, so that deformation of the stage apparatus  2  due to excessive constraints can be prevented. Furthermore, since the hydrostatic bearing  5  is disposed at the above-mentioned support point, deformation of the positioning mount  3  due to the injection of the compressed air can be reduced to the minimum degree. The second embodiment is the same as the first embodiment concerning the guide, auxiliary mount, and so forth, and a description thereof is, therefore, omitted.  
         [0041]     A modification of the second embodiment of the present invention will be described with reference to  FIGS. 8A and 8B . In the modification, spacers  34  and butting members  35  are interposed between the above-discussed base  1  and positioning mount  3 . The height of the butting member  35  is set to be smaller than that of the spacer  34  for supporting the positioning mount  3  by a small amount. When the stage apparatus  2  is moved from the auxiliary mount  7  to the positioning mount  3 , deformation of the positioning mount  3  is likely to occur with the movement of the stage apparatus  2 . At this time, when the positioning mount  3  deforms by the amount of a difference between the spacer  34  and the butting member  35 , the bottom surface of the positioning mount  3  is brought into butting contact with the butting member  35 , and supported thereby. Accordingly, the amount of deformation of the positioning mount  3  can be advantageously reduced to an amount below a predetermined amount.  
         [0042]     In the embodiments discussed above, the roller  41  can be a ball serving as a rolling member. In this case, the stage apparatus  2  can be two-dimensionally moved on a plane within an allowable range permitted by the retainer  42 , the guide grooves  2   a  and  3   a,  and so forth.  
         [0043]     Further, the auxiliary base  6  for supporting the auxiliary mount  7  can be comprised of a self-supporting structure. The screw  11  for lifting the stage apparatus  2  can be assembled in the base  1 . The cylinder  20  can be disposed in the stage apparatus  2 . Moreover, the hydrostatic bearing  5  can be constructed on the side of the supporting surface of the positioning mount  3 .  
         [0044]     As discussed in the foregoing, in the positioning apparatus, the stage apparatus is conveyed onto the movement surface of the auxiliary mount, and moved to the supporting surface of the positioning mount of a body apparatus, such as an exposure apparatus, using the rolling guide, and the stage apparatus is then lifted using the lifting unit to extract the rolling guide. After that, the stage apparatus is lowered onto the supporting surface. When the stage apparatus is positioned while being in contact (abutment) with the reference member, the stage apparatus is caused to float from the supporting surface by the hydrostatic bearing unit.  
         [0045]     When the stage apparatus is conveyed from the movement surface to the supporting surface, even a very heavy stage apparatus can be lightly moved because the weight of the stage apparatus is supported by the rolling guide.  
         [0046]     When the stage apparatus is positioned on the supporting surface using the reference member, the rolling guide is extracted and the stage apparatus is then supported by the hydrostatic bearing unit in a non-contact manner. Accordingly, highly-precise positioning can be efficiently performed. It is thus possible to quickly and precisely position the stage apparatus for supporting a workpiece or a measurement object, and to drastically improve the assemblage efficiency of an exposure apparatus, and the like.  
         [0047]     Except as otherwise discussed herein, the various components shown in outline or in block form in the Figures are individually well known and their internal construction and operation are not critical either to the making or using or to a description of the best mode of the invention.  
         [0048]     While the present invention has been described with respect to what are at present considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. The present invention is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the appended claims.