Abstract:
An exposure apparatus includes a projection device for projecting a pattern drawn on a surface of a master, a stage apparatus which moves at least a substrate of the master and a substrate relative to the projection device, and an exposure device for repeatedly exposing the substrate to the pattern of the master. A plurality of pipes connected to movable units of the stage apparatus are joined to each other at partial outer surfaces of the pipes and constitute an integrated pipe array. Electrical cables or signal line cables connected to the movable unit pass through hollow portions of some of the pipes serving as the integrated pipe array.

Description:
CLAIM OF PRIORITY 
   The present application claims priority under 35 U.S.C. § 119 from Japanese Patent Application No. 2003-193632, entitled “An Exposure Apparatus” and filed on Jul. 8, 2003, the entire contents of which are hereby incorporated by reference herein. 
   FIELD OF THE INVENTION 
   The present invention relates to an exposure apparatus used in a semiconductor manufacturing process, such as a projection exposure apparatus, which projects and transfers a reticle pattern onto a silicon wafer and, more particularly, to a stage apparatus, which moves a reticle and a silicon wafer by a reticle stage and a wafer stage that sequentially move the reticle and wafer, respectively, with respect to a projection exposure system when a reticle pattern is projected/exposed onto a wafer. 
   BACKGROUND OF THE INVENTION 
     FIGS. 1A and 1B  are views for explaining the prior art of the present invention and show X and Y piping assemblies on a wafer stage and cross sections of the X piping assembly, respectively. 
   As shown in  FIGS. 1A and 1B , a pressure air system comprises pressure air pipes  120   a  to  120   e , which supply pressure air. A vacuum system comprises vacuum pipes  120   f  and  120   g , which supply chuck vacuum air for a wafer  109  and chuck vacuum air for a wafer chuck  108 . A coolant system comprises coolant pipes  120   h  and  120   i , which supply/recover a coolant. An electrical system comprises electrical cables  120   j  and  120   k , which supply signals and driving currents among an illuminance sensor  112  on a fine adjustment stage  107 , a photosensor within a stage reference mark  113 , and driving units. A Y piping assembly  121  has almost the same arrangement as that of an X piping assembly and aims at movably connecting pipes in the Y direction. A pipe coupling wire  122  binds the piping assemblies of the respective systems to connect the pipes  120   a  to  120   g  of the pressure air and vacuum systems, the coolant pipes  120   h  and  120   i  of the coolant system, and the electrical cables  120   j  and  120   k  of the electrical system in almost a belt-like manner. A piping assembly of this type and an arrangement based on the same concept are disclosed in Japanese Patent Laid-Open No. 11-030294. 
   However, in the above-mentioned prior art example, the pipes of the systems are separately connected to a stage movable unit. When the stage movable unit moves, the pipes of the systems may rub against each other, may warp at an indefinite position, or may warp at the pipe coupling portion. Disturbance from the connecting portion of each piping system may decrease the control accuracy of a stage. 
   When a stage apparatus is used in a low-humidity environment, such as a nitrogen-purged atmosphere or a vacuum, movement of the piping system connecting portions tends to generate static electricity to charge the surfaces of the respective piping members. An electrostatic spark may occur at an indefinite position between the pipes or between components on the stage apparatus to damage the pipes, the electrical cables, and the components of the stage. 
   The present invention has been made in consideration of the conventional drawbacks, and to provide an exposure apparatus capable of minimizing disturbance by a piping system connecting portion, dust, and electrostatic buildup on the surfaces of piping members. 
   SUMMARY OF THE INVENTION 
   According to the present invention, there is provided an exposure apparatus comprising projection means for projecting a pattern drawn on a surface of a master, moving means for causing a stage apparatus to move at least a substrate of the master and substrate relative to the projection means, and exposure means for repeatedly exposing the substrate to the pattern of the master, wherein a plurality of pipes, which are connected to movable units of the stage apparatus and have different inner and outer diameters, are joined to each other at partial outer surface of the pipes and constitute an integrated piping array. 
   When the apparatus is used in a low humidity environment in a vacuum, it is arranged in the following manner to prevent movement of each piping system connecting portion from generating static electricity on the surfaces of piping members. More specifically, a conductive material is added to a piping resin, or a conductive film is sputtered on the surface of the pipes. Alternatively, different types of tubes are used for the inner and outer surfaces of the pipes, and the outer surfaces are made conductive, thereby forming a layer structure. With this arrangement, any potential charged on the surface of each tube is grounded and discharged to, e.g., chassis ground. 
   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 
     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. 
       FIGS. 1A and 1B  are views showing a prior art stage and cross sections of a piping assembly, respectively; 
       FIG. 2  is a view showing the entirety of an exposure apparatus according to the present invention; 
       FIG. 3  is a perspective view of a stage apparatus according to the present invention; 
       FIGS. 4A and 4B  are views showing a wafer stage  4  and a cross section of a stage piping assembly, respectively, according to the first embodiment; 
       FIG. 5  is a view showing the cross section of a stage piping assembly according to the second embodiment; 
       FIG. 6  is a view showing the cross section of a stage piping assembly according to the third embodiment; 
       FIG. 7  is a view showing the cross section of a stage piping assembly according to the fourth embodiment; 
       FIG. 8  is a view showing the cross section of a stage piping assembly according to the fifth embodiment; 
       FIGS. 9A to 9D  are views showing the cross sections of stage piping assemblies according to the sixth embodiment; 
       FIG. 10  is a view showing a piping rail  30  (conductive material) in which a chassis ground  31  is arranged within a range wherein antistatic piping tubes  26  to  29  flexibly move, according to the seventh embodiment; 
       FIG. 11  is a view showing a Y piping assembly  32  in a reticle stage  2 , according to the eighth embodiment; and 
       FIGS. 12A to 12C  are views showing the states and cross sections, respectively, of Y piping assemblies arranged almost symmetrically with respect to the reticle stage  2 , according to the eighth embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings. 
   First Embodiment 
     FIGS. 2 and 3  are views showing an exposure apparatus common to each embodiment and a wafer stage which constitutes a part of the exposure apparatus, respectively. 
   In  FIG. 2 , reference numeral  1  denotes an illumination system unit, which comprises an exposure light source and has a function of shaping exposure light emitted from the exposure light source and irradiating a reticle with the exposure light. Reference numeral  2  denotes a reticle stage, which has the reticle serving as an exposure pattern master on it and has a function of performing a reticle scan operation for a wafer at a predetermined reduction exposure magnification ratio to the wafer. Reference numeral  3  denotes a reduction projection lens, which reduces and projects a master pattern onto the wafer (substrate). Reference numeral  4  denotes a wafer stage ( 4 ), which has a function of sequentially continuously moving the substrate (wafer) for every exposure process. 
   Reference numeral  5  denotes an exposure apparatus main body ( 5 ), which supports the reticle stage  2 , reduction projection lens  3 , and wafer stage  4 . Reference numeral  6  denotes an alignment scope, which measures an alignment mark on the wafer and an alignment reference mark on the stage and performs measurement in alignment within the wafer and alignment between the reticle and the wafer. 
     FIG. 3  is a view showing in detail the wafer stage  4  in  FIG. 2 . 
   In  FIG. 3 , reference numeral  7  denotes a fine adjustment stage, which finely adjusts the wafer on the stage in a direction of an optical axis of a reduction exposure system, a tilt direction, and a rotational direction about the optical axis. Reference numeral  8  denotes a wafer chuck, which supports and fixes the wafer to the fine adjustment stage  7 . Reference numeral  9  denotes a wafer. In the wafer  9 , the surface of a single-crystal Si substrate is coated with a resist to project and transfer a reticle pattern drawn on a reticle substrate onto the wafer  9  through the reduction exposure system. 
   Reference numeral  10  denotes an X bar mirror, which serves as a target when a laser interferometer measures the X-direction position of the fine adjustment stage  7 . Reference numeral  11  denotes a Y bar mirror, which serves as a target in measuring the Y-direction position, similar to the X bar mirror. Reference numeral  12  denotes an illuminance sensor arranged on the upper surface of the fine adjustment stage  7 . The illuminance sensor  12  performs calibration measurement for the illuminance of exposure light before exposure and uses the obtained illuminance to correct light exposure. Reference numeral  13  denotes a stage reference mark arranged on the upper surface of the fine adjustment stage  7 . A target for stage alignment measurement is formed in it. 
   Reference numeral  14  denotes an X linear motor, which moves and drives the fine adjustment stage  7  in the X direction. Reference numeral  15  denotes an X guide for guiding X-axis movement of the fine adjustment stage  7 . Reference numeral  16  denotes a Y guide for moving and guiding the X guide  15  and fine adjustment stage  7  in the Y direction. Reference numeral  17  denotes a stage surface plate, which two-dimensionally guides the fine adjustment stage  7 . Reference numerals  18  and  19  denote Y linear motors for moving and driving the fine adjustment stage  7  in the Y direction. 
   Reference numeral  20  denotes an X piping assembly. The X piping assembly  20  aims at movably connecting in the X direction a plurality of pipes, which supply pressure dry air or vacuum air to an air bearing system (not shown) or the wafer chuck  8  mounted on the fine adjustment stage  7 , pipes which supply and recover a liquid cooling medium for cooling the driving units inside the fine adjustment stage  7 , and electrical cables, which transmit signals and feed currents between sensor systems and the driving units mounted on the fine adjustment stage  7 . 
     FIGS. 4A and 4B  are views showing piping assemblies according to the first embodiment.  FIG. 4A  shows the layout relationship between the wafer stage  4 , and the X piping assembly  20  and a Y piping assembly  21 .  FIG. 4B  is a view showing the cross section of the X piping assembly according to the first embodiment. 
   As shown in  FIGS. 4A and 4B , a pressure air system has pressure air pipes  20   a  to  20   e , which supply pressure air. 
   A vacuum system has vacuum pipes  20   f  and  20   g , which draw chuck vacuum air of the wafer  9  and chuck vacuum air of the wafer chuck  8 . 
   A coolant system has coolant pipes  20   h  and  20   i , which supply and recover a coolant. 
   An electrical system supplies signals and driving currents between the illuminance sensor  12  on the fine adjustment stage  7 , a photosensor within the stage reference mark  13 , and the driving units through electrical cables  20   j  and  20   k  extending inside an electrical-cable-incorporated pipe  20   m.    
   The Y piping assembly  21  has almost the same arrangement as that of the X piping assembly and aims at movably connecting the pipes in the Y direction. The arrangement of the Y piping assembly  21  is similar to that of the X piping assembly  20 . 
   As shown in  FIGS. 4A and 4B , the pressure air pipes  20   a  to  20   e  serving as the pressure air system, coolant pipes  20   h  and  20   i  serving as the cooling system, and electrical-cable-incorporated pipe  20   m , are connected to each other at their outer surfaces and are integrated as a belt-like pipe array. A polyurethane tube, or the like, is employed as a piping material. 
   The electrical-cable-incorporated pipe  20   m  has almost the same diameter as that of the coolant pipes  20   h  and  20   i . This prevents the piping assembly from readily breaking at the electrical-cable-incorporated pipe. Direct integration like the array shown in the prior art can enjoy the advantages of integration. However, the electrical cables described in the prior art are much thinner than any other pipe and, thus, tend to break. 
   The diameter of the electrical-cable-incorporated pipe  20   m  may be made equal to that of the pressure air pipes or may be set between the pressure air pipes and the coolant pipes. 
   As described above, according to the first embodiment, the pressure air system, cooling system, and electrical-cable-incorporated pipe are integrated as a belt-like pipe array. This arrangement prevents any rub of the pipes of the respective systems against each other, any warp of the pipes at an indefinite position, and any warp of the pipes at a pipe coupling portion, when each stage movable unit moves. This makes it possible to reduce disturbance to the stage movable unit and dust from the pipes and to increase the stage control accuracy and alignment precision. 
   Second Embodiment 
     FIG. 5  is a view showing the arrangement of a piping assembly according to the second embodiment. 
   The piping assembly according to the second embodiment is characterized in that it is formed by joining vibration damping pipes  23  (gel with a large internal loss and a liquid area sealed inside the pipes) at both ends of a piping assembly according to the first embodiment. Each vibration damping pipe  23  can be filled with, e.g., a gelatinous material  23 A with a large internal loss, a liquid, a polymeric material, and the like. 
   The vibration damping pipes at both ends of the piping assembly comprising pipes make it possible to damp vibrations of the pipes themselves, which move as a stage moves. The second embodiment, which has the arrangement of the first embodiment as well, prevents any rub of the pipes of respective systems against each other, any warp of the pipes at an indefinite position, and any warp of the pipes at a pipe coupling portion, when each stage movable unit moves. This makes it possible to reduce disturbance to the stage movable unit and dust from the pipes and to increase the stage control accuracy and alignment precision. 
   Third Embodiment 
     FIG. 6  is a view showing the arrangement of a piping assembly according to the third embodiment. 
   The piping assembly according to the third embodiment is characterized in that a vibration damping pipe  23 B (a gelatinous material  23 A with a large internal loss, a liquid, a polymeric material, and the like, are sealed inside the pipe) is provided for a piping assembly according to the first embodiment so as to enclose the outer surfaces of the pipes. The vibration damping pipe  23 B is filled with, e.g., the gelatinous material  23 A with a large internal loss, a liquid, a polymericl material, and the like, as described in the second embodiment. 
   The vibration damping pipe  23 B so arranged as to enclose the outer surfaces of the pipes makes it possible to damp vibrations of the pipes themselves, which move as a stage moves. 
   The third embodiment, which has the arrangement of the first embodiment as well, prevents any rub of the pipes of respective systems against each other, any warp of the pipes at an indefinite position, and any warp of the pipes at an indefinite position, and any warp of the pipes at a pipe coupling portion, when each stage movable unit moves. This makes it possible to reduce disturbance to the stage movable unit and dust from the pipes and to increase the stage control accuracy and alignment precision. 
   Fourth Embodiment 
     FIG. 7  is a view showing the arrangement of a piping assembly according to the fourth embodiment. 
   The above-mentioned embodiments use a polyurethane tube as a piping material. The fourth embodiment is characterized by using thermoplastic fluororesin tubes  24  with lower water absorption. 
   With this arrangement, a piping assembly with a smaller water loss can be implemented in a stage apparatus in a vacuum environment or a stage apparatus in an environment purged of air (oxygen) with nitrogen, helium, or the like. 
   Fifth Embodiment 
     FIG. 8  is a view showing the arrangement of a piping assembly according to the fifth embodiment. 
   The fourth embodiment uses a thermoplastic fluororesin tube as a piping material. The fifth embodiment is characterized by using thermoplastic fluororesin tubes  25   a  with lower water absorption as the inner and outer surfaces of each tube and using a polyurethane tube  25   b  as the intermediate layer of the tube. 
   Use of multilayered polyurethane/thermoplastic fluororesin tubes  25 , including the thermoplastic fluororesin tube  25   a  and polyurethance tube  25   b , makes it possible to implement a piping assembly with a smaller water loss in a stage apparatus in a vacuum environment or a stage apparatus in an environment purged of air (oxygen) with nitrogen, helium, or the like. 
   Sixth Embodiment 
     FIGS. 9A to 9D  are views showing the sixth embodiment. 
   The fifth embodiment uses a polyurethane or thermoplastic fluororesin tube as a piping material. The sixth embodiment considers measures against electrostatic buildup on the surfaces of tubes. This embodiment is particularly effective when it is used in a low-humidity environment in a vacuum. 
   As shown in  FIG. 9A , this embodiment is characterized by using conductive polyurethane or conductive thermoplastic fluororesin tubes  26  as piping tubes. Each of these tubes is formed by adding a conductive filler such as carbon powder to the base material of a polyurethane or thermoplastic fluororesin tube according to the first embodiment. Rendering the tubes conductive and grounding their surfaces to chassis ground make it possible to prevent electrostatic buildup. 
   Alternatively, as shown in  FIG. 9B , this embodiment is characterized by using conductive-material-deposited tubes  27  whose surfaces are conductive as piping tubes. Each conductive-material-deposited tube  27  can be manufactured by forming a conductive material deposition layer  27   a  on the surface of the piping tube by sputtering, or the like. Similar to the example of  FIG. 9A , rendering the tubes conductive and grounding their surfaces to chassis ground make it possible to prevent electrostatic buildup. 
   Alternatively, as shown in  FIG. 9C , this embodiment is characterized by using, as piping tubes, multilayered polyurethane/thermoplastic fluororesin tubes  28  each having thermoplastic fluororesin tubes  28   a  with lower water absorption as the inner and outer surfaces of the tube and a polyurethane tube  28   b  as the intermediate layer of the tube. A conductive material deposition layer  28   c  is formed on the surface by sputtering, or the like. With this arrangement, a piping assembly with a smaller water loss, which can prevent electrostatic buildup, can be implemented in a stage apparatus in a vacuum environment or a stage apparatus in an environment purged of air (oxygen) with nitrogen, helium, or the like. 
   Alternatively, as shown in  FIG. 9D , this embodiment is characterized by arranging conductive flexible sheets  29  adjacent to the upper and lower surfaces of integrally coupled piping tubes and grounding the conductive flexible sheets  29  to a stage chassis. This makes it possible to remove charges from the surfaces of the piping tubes. 
   The above description has explained an embodiment, which considers measures against electrostatic buildup on the surfaces of tubes. 
   Seventh Embodiment 
     FIG. 10  is a view showing the seventh embodiment. 
   The seventh embodiment is characterized by providing a piping rail  30  (conductive material) in which chassis ground  31 , as shown in  FIG. 10 , is arranged within a range where the antistatic piping tubes  26  to  29 , described in the sixth embodiment, flexibly move. 
   This piping rail makes it possible to ground the surfaces of the conductive piping tubes to the piping rail, i.e., directly to chassis ground. 
   In the piping tubes  20 ,  24 , and  25  described in the first to fifth embodiments, which are not conductive, an antistatic effect can be expected. 
   Eighth Embodiment 
     FIG. 11  shows the eighth embodiment, i.e., a Y piping assembly  32  in a reticle stage  2 . 
   Each of the first to seventh embodiments has described piping assemblies in a wafer stage. In the eighth embodiment, the Y piping assembly  32  performs scan movement in accordance with a movable unit of the reticle stage  2 , which performs a reticle scan operation for a wafer at a predetermined reduction exposure magnification ratio in the reticle stage, on which a reticle serving as an exposure pattern master is mounted. The Y piping assembly  32  can have the same arrangement as those of the above-mentioned embodiments. 
   Ninth Embodiment 
     FIGS. 12A to 12C  show the ninth embodiment.  FIG. 12A  shows a reticle stage, and  FIGS. 12B and 12C  show cross sections, respectively, of Y piping assemblies arranged on the reticle stage. 
   In the first to eighth embodiments, an integrated pipe array is arranged on one side of the moving direction of a movable unit of a stage apparatus. The ninth embodiment is characterized in that pipe arrays are arranged symmetrically with respect to the moving direction of the stage apparatus. 
   As shown in  FIGS. 12A to 12C , a Y piping assembly  33  and Y piping assembly  34  (pipe arrays) are arranged almost symmetrically with respect to a moving direction of a reticle stage  2 . With this arrangement, moving resistances from the integrated pipe arrays are symmetrically applied when the stage moves in the moving direction. This makes it possible to suppress generation of yawing in stage movement and to perform stable movement control. 
   In the Y piping assembly  33  on the left side of the reticle stage  2 , one of vibration damping pipes  23  (gel with a large internal loss and a liquid are sealed inside the pipe) and pressure air pipes  20   a  to  20   e  are integrally arranged in this order, as shown in  FIG. 12B . 
   In the Y piping assembly  34  on the right side of the reticle stage  2 , the remaining vibration damping pipe  23  (gel with a large internal loss and a liquid are sealed inside the pipe), coolant pipes  20   h  and  20   i , an electrical-cable-incorporated pipe  20   m  incorporating electrical cables  20   j  and  20   k , and vacuum pipes  20   f  and  20   g , are integrally arranged, in this order. 
   This symmetrical arrangement of the pipe arrays reduces assembly disturbance. At the same time, generating a moving load in the pipes symmetrically with respect to the movable units suppresses generation of yawing in movement. This can stabilize the alignment precision of the stage apparatus. 
   As has been described above, according to the present invention, separate connections from systems to a movable unit are integrated into a belt-like pipe array. This arrangement prevents any rub of the pipes of the respective systems against each other, any warp of the pipes at an indefinite position, and any warp of the pipes at a pipe coupling portion, when each stage movable unit moves. This makes it possible to reduce disturbance to the stage movable unit and dust from the pipes and to increase the stage control accuracy and alignment precision. 
   Also, the present invention is arranged such that movement of piping system connecting portions does not generate static electricity on the surface of piping members when a stage apparatus is used in a low-humidity environment in a vacuum. This arrangement prevents an electrostatic spark from generating at an indefinite position between the pipes or between components on the stage apparatus to damage the pipes, electrical cables, and the components on the stage. The reliability of the stage apparatus increases. 
   Note that the shapes and structures of the respective elements shown in the above-described embodiments are merely given as an example of implementation of the present invention, and the technical scope of the present invention is not limitedly interpreted with these shapes and structures. That is, the present invention can be implemented in various forms without departing from its spirit and its principal features. 
   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 appended claims.