Abstract:
A stage base includes a plate which supports a stage. The plate has a first structure and a second structure, and the first and second structures are coupled. The stage base further includes a component which is arranged on the plate and has a cooling unit, a coolant channel arranged to extend through the plate into the component, and a seal member arranged between the first structure and the second structure so as to surround the coolant channel, an interior and an exterior of the seal member being fastened with a fastener.

Description:
[0001]     This application is a divisional application of copending U.S. patent application Ser. No. 10/943,010, filed Sep. 17, 2004. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a stage base applied to a stage apparatus and, more specifically, to a stage apparatus having a cooling mechanism, which is coupled to a fine adjustment stage and can perform cooling by the circulation of a cooling medium. The present invention also relates to an exposure apparatus and a device manufacturing method which use the stage apparatus.  
       BACKGROUND OF THE INVENTION  
       [0003]     There is available an exposure apparatus, such as a stepper, which projects, onto a wafer, a pattern drawn on a mask or a reticle for manufacturing semiconductor devices (see, e.g., Japanese Patent No. 3,145,355). This type of exposure apparatus has a function of aligning a wafer and a reticle before exposure. There are generally two types of alignment methods, a step and repeat type method, and a step and scan type method. The step and repeat type method measures a shift between a master, such as a reticle bearing a pattern for exposure, and an object to be exposed (substrate), such as a wafer, and repeatedly steps the object to be exposed on the basis of the measurement result, thereby performing exposure. The step and scan type method moves the master and the object to be exposed relative to each other, thereby performing exposure. These exposure apparatuses are required in terms of resolution and overlay accuracy to align at extremely high precision a wafer stage, which moves while holding an object to be exposed (e.g., a wafer). In recent years, high-speed alignment has been demanded in order to increase the productivity.  
         [0004]      FIG. 7  is a perspective view showing a conventional wafer stage in an exposure apparatus. In  FIG. 7 , a Y stage  54  serving as a moving mechanism in the Y direction is mounted on a stage surface plate  55 . An X stage  51  serving as a moving mechanism in the X direction is mounted on the Y stage  54 . In this manner, the Y stage  54  and X stage  51  constitute an X-Y stage  56 .  
         [0005]      FIG. 8  is a schematic view showing the arrangement of the X-Y stage. The stage surface plate has a reference plane whose upper surface is smooth. The X-Y stage  56  comprises the Y stage  54  ( 54   a ,  54   b ,  54   c , and  54   d ) serving as a moving member and X stage  51  serving as a moving member. A fixed guide  52  is provided in the horizontal direction (Y-axis direction) of the Y stage  54 . Porous hydrostatic air bearings are provided in the horizontal direction (X-axis direction) of the X stage  51 , the vertical direction (Z-axis direction) of the X stage  51 , the horizontal direction (Y-axis direction) of the Y stage  54 , and the vertical direction of the Y stage  54 , respectively, to guide the stages.  
         [0006]     The Y stage  54  levitates from the stage surface plate  55  by supplying air to the hydrostatic air bearings. The Y stage  54  moves by the driving actuators  54   c  on both sides of the stage surface plate  55  in the Y direction along the fixed guide  52  on one side. The X stage  51  levitates from the stage surface plate  55  by supplying air to the hydrostatic air bearings, similarly to the Y stage  54 . The X stage  51  moves by a driving actuator  51   c  in the X direction using the side surfaces  54   b  of the Y stage  54  as a horizontal guide. At this time, a plurality of pressure applying magnetic units (not shown) adjust the X stage  51  and Y stage  54  so as to maintain respective constant postures.  
         [0007]      FIG. 9  is a schematic view showing the arrangement of a fine adjustment stage  90 . The X-Y stage  56  (see  FIG. 8 ) having a reference plane which exerts a thrust or an attraction force on the fine adjustment stage  90  is arranged below the fine adjustment stage  90 . The fine adjustment stage  90  is mounted in non-contact with a stage base  50 ′ on the X stage  51 . The X-Y stage  56  has linear motors  11 ,  12  and  13 , which finely control the posture of the fine adjustment stage  90  with respect to the reference plane, and cylindrical electromagnet units  21 ,  22  and  23 , which transmit acceleration in the X and Y directions to the fine adjustment stage  90 . The fine adjustment stage  90  also comprises a self-weight compensating mechanism  3  for supporting its own weight.  
         [0008]     With this arrangement, a thrust can be applied by the linear motors  11 ,  12 , and  13  from the X-Y stage  56  to the fine adjustment stage  90 . A large attraction force in the X and Y directions can be applied by the electromagnet units  21 ,  22 , and  23 .  
         [0009]     When the fine adjustment stage  90  is supported in non-contact with the X-Y stage  56 , the linear motors  11 ,  12 , and  13  are required to have the capability to accelerate the fine adjustment stage  90  at a desired acceleration. For this reason, the linear motors  11 ,  12 , and  13  are predicted to generate heat in driving the fine adjustment stage  90 . To cope with this, the linear motors  11 ,  12 , and  13  have cooling mechanisms. The cooling mechanisms suppress external leakage of heat generated in the linear motors  11 ,  12 , and  13 .  
         [0010]      FIG. 10  is a schematic view showing a linear motor coil  113 , which is arranged on a support surface  100 ′ of the stage base  50 ′ to drive the fine adjustment stage  90 , and a component  1 , which comprises a cooling mechanism for cooling the linear motor coil  113 . The component  1  is generally formed by covering the linear motor coil  113  with a jacket  112  and is arranged to supply a cooling medium into the jacket  112  using a resin tube  111 . With this arrangement, the component  1  can cool the linear motor coil  113 .  
         [0011]     As for the electromagnet units  21 ,  22 , and  23  shown in  FIG. 9 , a large attraction force is applied to the fine adjustment stage  90  when driving the X-Y stage  56  shown in  FIGS. 7 and 8 . For this reason, the coils of the electromagnet units  21 ,  22 , and  23  are also predicted to generate heat. Providing a cooling mechanism for the coils of the electromagnet units  21 ,  22 , and  23  in the same manner as that for the linear motors  11 ,  12 , and  13  can suppress external leakage of heat generated in the coils. Similar to the linear motors, each of the cooling mechanisms is formed by covering its coil with a jacket and is arranged to supply a cooling medium into the jacket using the resin tube  111 .  
         [0012]     A conventional stage apparatus which distributes and supplies through resin tubes a cooling medium to components having cooling mechanisms coupled to a fine adjustment stage has the following problems.  
         [0013]     (1) If each resin tube is fixed and arranged on a stage base so as to prevent vibration of the resin tube, the size of a mounting portion for mounting the resin tube increases, and the mounting portion may interfere with surrounding components or may increase in mass.  
         [0014]     (2) Guiding the resin tubes increases disturbance and interferes with high-precision alignment.  
         [0015]     If the stage apparatus is placed in a vacuum chamber and used in a vacuum environment or a reduced-pressure environment, outgassing occurs in a large quantity from the resin tubes. This may cause contamination (adhesion of a contaminant) or may decrease the vacuum degree in the vacuum chamber.  
       SUMMARY OF THE INVENTION  
       [0016]     The present invention has been made in consideration of the above-mentioned problems, and has as its object to minimize the number of resin tubes used to supply a cooling medium to components having cooling units.  
         [0017]     According to the present invention, there is provided a stage base comprising a plate which supports a stage, a component which is arranged on a support surface and has a cooling unit, and a coolant channel which is arranged so as to extend through the plate into the component.  
         [0018]     Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
         [0020]      FIG. 1  is a view showing a stage base according to a preferred embodiment of the present invention and a cooling unit applied to a fine adjustment stage;  
         [0021]      FIG. 2  is a view showing the first arrangement example according to the preferred embodiment of the present invention;  
         [0022]      FIG. 3  is an enlarged view of the vicinity of a threaded hole portion formed inside a seal groove;  
         [0023]      FIG. 4  is a view showing the second arrangement example according to the preferred embodiment of the present invention;  
         [0024]      FIG. 5  is a view showing the third arrangement example according to the preferred embodiment of the present invention;  
         [0025]      FIG. 6  is an enlarged view of an adhesive reservoir and a threaded hole portion formed within the adhesive reservoir;  
         [0026]      FIG. 7  is a perspective view showing a wafer stage applied to a conventional exposure apparatus;  
         [0027]      FIG. 8  is a schematic view showing the arrangement of a conventional X-Y stage;  
         [0028]      FIG. 9  is a schematic view showing the arrangement of a conventional fine adjustment stage;  
         [0029]      FIG. 10  is a schematic view showing a conventional stage base and a cooling unit applied to a fine adjustment stage; and  
         [0030]      FIG. 11  is a view showing the concept of an exposure apparatus which uses a stage apparatus according to the preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]     The present invention will be described in detail with reference to the accompanying drawings.  
         [0032]      FIG. 1  is a view showing a stage base  50  according to a preferred embodiment of the present invention, and components  1  each having a cooling unit coupled to the stage base  50 .  FIG. 1  is an exploded view showing a linear motor stator jacket as an example of the component  1  having the cooling unit.  
         [0033]     As shown in  FIG. 1 , the stage base  50  is formed as one structure by fastening two structures, a base plate  50   a  and base plate  50   b , with fasteners, such as bolts. The base plate  50   b  has a support surface  100 , which movably supports a fine adjustment stage  90  ( FIG. 9 ) having a fine stroke. A stage apparatus according to this embodiment is roughly obtained by partially changing the arrangement of the stage apparatus shown in  FIG. 7  or  8 . More specifically, in the stage apparatus according to this embodiment, the stage base  50  shown in  FIG. 1  is provided on the X stage  51  in  FIG. 8 , instead of the stage base  50 ′. As the material for the stage base  50 , a ceramic material is preferably used for weight reduction and high rigidity. However, the present invention is not limited to this, and another material, such as a metal may be used.  
         [0034]     Grooves  41  are formed in the surface of the base plate  50   a . Fastening the base plate  50   a  and base plate  50   b  forms internal channels for distributing and supplying a cooling medium  42  between the grooves  41  and the base plate  50   b . A seal groove  44  is formed in the base plate  50   a  so as to surround the grooves  41 . Fitting an O-ring (not shown) serving as a seal member into the seal groove  44  makes it possible to prevent the cooling medium circulating through the grooves  41 , serving as the internal channels, from leaking outside the stage base  50 . Note that the seal member is not limited to this O-ring. For example, a gasket or an adhesive may be used instead. The fine adjustment stage  90  is preferably arranged to have three or more degrees of freedom.  
         [0035]     Linear motor coils  113  for driving the fine adjustment stage  90  in  FIG. 9  and the components  1  having cooling mechanisms for cooling the linear motor coils  113  are arranged on the support surface  100  of the stage base  50 . Each component  1  is arranged on the support surface  100  so as to cover the corresponding linear motor coil  113 .  
         [0036]     Seal grooves  61  are formed in the base plate  50   b . Providing a seal member, such as an O-ring (not shown), for each seal groove  61  and fastening the components  1  (e.g., linear motor stator jackets) having the cooling units to the stage base  50  makes it possible to prevent the cooling medium from leaking to the outside. A through-hole  61 ′, which communicates with the corresponding groove  41 , is formed inside each seal groove  61 . Coupling the components  1  on the support surface  100  to the through-holes  61 ′ makes it possible to directly supply the cooling medium to the components  1  through the grooves  41 . Thus, the resin tube  111  ( FIG. 10 ) used to couple the stage base  50  and each component  1  becomes unnecessary.  
         [0037]     In this embodiment, the seal grooves  61  are formed in the base plate  50   b . The present invention, however, is not limited to this, and the seal grooves  61  may be formed in the linear motor statorjackets  1 . In this embodiment, the grooves  41  are formed in the base plate  50   a . The present invention, however, is not limited to this. The grooves  41  need only be formed in at least one of the base plates  50   a  and  50   b , which constitute the stage base  50 . The seal groove  44  is formed in the member having the grooves  41  (in this embodiment, the base plate  50   a ). The present invention, however, is not limited to this. The seal groove  44  need only be formed in at least one of the base plates  50   a  and  50   b . In this embodiment, the two flat plates are fastened to form the channels inside the stage base  50 . The present invention, however, is not limited to this. The grooves  41  may be formed inside one flat plate.  
         [0038]     Arrangement examples of stage bases according to the preferred embodiment of the present invention will be described with reference to  FIG. 2 . The grooves  41  (hatched portions), serving as the internal channels, are formed in the surface of the base plate  50   a . Inlets  41   a  are ports through which the supplied cooling medium flows out. The grooves  41  serving as the internal channels comprise a plurality of lines. The plurality of lines can be arranged to have almost the same line resistance. More specifically, the grooves  41  can be arranged such that the channels have almost the same line resistance when the cooling medium from the inlets  41   a  passes through the grooves  41  and components  1  to the outlets  41   b . The seal groove  44  is formed outside the grooves  41 . The seal groove  44  uses the seal member, such as an O-ring, to prevent the cooling medium flowing through the grooves  41  from leaking outside the stage base  50 .  
         [0039]     Threaded hole portions  45  and  46  are formed to fasten the base plate  50   a  and the base plate  50   b  of  FIG. 1  with fasteners, such as bolts. To suppress a stress which acts on the ceramic plate  50   b  when applying a force to the seal member, such as an O-ring, the threaded hole portions  45  and  46  are desirably arranged on both sides of the O-ring.  
         [0040]      FIG. 3  is an enlarged view of the vicinity of each threaded hole portion  45  inside the seal groove  44 . The threaded hole portion  45  comprises a threaded hole  45   b  and a groove  45   a  (hatched portion) for a seal member, such as an O-ring. The cooling medium supplied to the grooves  41  may enter the gap between the base plate  50   a  and the base plate  50   b  due to the internal pressure of the cooling medium. For this reason, to prevent the cooling medium from leaking from the threaded hole  45   b  outside the stage base, it is desirable to form the seal groove  45   a  around the threaded hole  45   b  inside the seal groove  44  and to perform sealing with a seal member, such as an O-ring.  
         [0041]     The stage base in the first arrangement example has at least the following features.  
         [0042]     (1) A cooling medium is directly supplied through the internal channels to the components, each of which is used for, e.g., a linear motor, and has the cooling unit. With this arrangement, interference with surrounding components due to resin tube coupling and disturbance in high-precision alignment can be suppressed.  
         [0043]     (2) The grooves are formed such that internal channels have almost the same line resistance when the cooling medium is supplied from each inlet of the stage base to the component having the cooling unit. With this arrangement, these members can uniformly be cooled.  
         [0044]     In this arrangement example, the threaded hole portions  45  and  46  for fastening the stage base  50  are formed on the ceramic plate  50   a  side. The present invention, however, is not limited to this, and the threaded hole portions  45  and  46  may be formed on the ceramic plate  50   b  side.  
       Second Arrangement Example  
       [0045]      FIG. 4  is a view exemplifying the second arrangement example, which is a modification of the first arrangement example shown in  FIG. 2 . The same reference numerals as those in this arrangement example denote the same parts as those in the first arrangement example. In the arrangement example of  FIG. 2 , the base plates  50   a  and  50   b  are fastened with fasteners, such as bolts, in the threaded hole portions  45  and  46  on both sides of the seal groove  44 . The arrangement example of  FIG. 4  considers a case wherein the stage base is used in a vacuum environment or a reduced-pressure environment. The arrangement of  FIG. 4  is obtained by adding to the arrangement of  FIG. 2  adhesive reservoirs  47  for filling, with an adhesive (not shown), portions within the seal groove  44 , except for the grooves  41 . With this arrangement, the second arrangement example has the following feature, in addition to the features (1) and (2) described in the first arrangement example.  
         [0046]     (3) When a cooling medium supplied to the internal channels enters the gap region between the base plate  50   a  and the base plate  50   b , except for the internal channels, the adhesive reservoirs reduce an area on which a pressure difference between the cooling medium and the outside of the stage base (vacuum or reduced-pressure atmosphere) acts (area in which the cooling medium may flow). This makes it possible to reduce a force by the pressure difference and more securely fix the base plates  50   a  and  50   b . Stress concentration on the threaded hole portions  45 , through which the base plates  50   a  and  50   b  are fastened, can, therefore, be relaxed.  
       Third Arrangement Example  
       [0047]      FIG. 5  is a view exemplifying the third arrangement example, which is a modification of the second arrangement example shown in  FIG. 4 . The same reference numerals as those in this arrangement example denote the same parts as those in the second arrangement example. This arrangement example is obtained by adding to the arrangement of  FIG. 4  threaded hole portions  48  within the respective adhesive reservoirs  47 .  FIG. 6  is an enlarged view of each adhesive reservoir  47  and the threaded hole portion  48  inside the adhesive reservoir  47 . A threaded hole  48   b  is used to fasten the base plates  50   a  and  50   b  with fasteners such as bolts. A seal groove  48   a  (hatched portion) is a groove for a seal member, such as an O-ring, formed to prevent the cooling medium from leaking from the threaded hole  48   b  outside the stage base. A partition wall  48   c  is formed between the seal groove  48   a  and the adhesive reservoir  47  and can inhibit the cooling medium from leaking outside more effectively.  
         [0048]     This arrangement example has the above-mentioned structure, in addition to the arrangement of  FIG. 4 . This arrangement example has the following features, in addition to the features (1) to (3) described in the first and second arrangement examples.  
         [0049]     (4) By fastening the interiors of the respective adhesive reservoirs  47  with fasteners, such as bolts, a shearing force, which is generated by a pressure difference between the cooling medium and the outside of the stage base (vacuum or reduced-pressure atmosphere) and acts on the adhesive, is relaxed. Thus, peeling of the adhesive can be prevented.  
         [0050]      FIG. 11  is a view schematically showing the arrangement of an exposure apparatus, which incorporates the stage apparatus according to the preferred embodiment of the present invention. In the example shown in  FIG. 11 , the stage apparatus is mounted as a wafer stage  700 , and a mask stage  500  is mounted above the wafer stage  700 . In the mask stage  500 , a mask is held by a chuck above the mask stage  500 . In the wafer stage  700 , a wafer is held by a chuck provided for the fine adjustment stage  90 . The mask is illuminated by an illumination optical system  601 . The image of a pattern formed on the mask is projected and transferred onto the wafer through a projection optical system  602 . In this manner, the exposure apparatus can align an object to be aligned (wafer) and perform an exposure operation, using the stage apparatus according to the preferred embodiment of the present invention. A photosensitive layer on the wafer serving as a substrate on which the pattern is transferred is developed to manufacture a semiconductor device. This exposure apparatus can be applied to a known manufacturing process of semiconductor devices.  
         [0051]     According to the present invention, the number of resin tubes used to supply a cooling medium to components having cooling units can be suppressed.  
         [0052]     As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the claims.  
         [0053]     This application claims priority from Japanese Patent Application No. 2003-335643 filed on Sep. 26, 2003, which is hereby incorporated by reference herein.