Patent Publication Number: US-2010118286-A1

Title: Exposure apparatus and device manufacturing method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an exposure apparatus for exposing a substrate to light via an immersion liquid, and a device manufacturing method. 
     2. Description of the Related Art 
     Recently, an immersion exposure apparatus exposing a wafer to light via an immersion liquid has been developed. A conventional immersion exposure apparatus  200  will be described with reference to  FIG. 10 .  FIG. 10  is a schematic diagram illustrating a conventional immersion exposure apparatus. 
     The immersion exposure apparatus  200  includes an illumination device  1 , a reticle stage  3 , a projection optical system  4 , a wafer stage  70 , and a nozzle unit  11 . 
     The illumination device  1  illuminates a reticle  2 . The reticle stage  3  holds the reticle  2 , and can move. The projection optical system  4  projects a pattern of the reticle  2 , which is illuminated by the illumination device  1 , on a wafer  5 . The wafer stage  70  holds the wafer  5  by a chuck  6 , and can move. 
     The nozzle unit  11  includes a supply port and a recovery port. The supply port supplies an immersion liquid  12  to between the projection optical system  4  and the wafer  5 . The recovery port recovers the immersion liquid  12  from between the projection optical system  4  and the wafer  5 . The supply port is connected with a supply pipe  13 , and the recovery port is connected with a recovery pipe  14 . 
     The wafer stage  70  includes an support plate  121 . The support plate  121  is placed around the wafer chuck  6 . The surface of the support plate  121  is set at approximately the same height as a surface of the wafer  5  held by the wafer chuck  6 . 
     A gap is formed between the support plate  121  and the wafer  5 . When an edge shot of the wafer  5  is exposed to light, the immersion liquid  12  exists on the gap, and thus enters the gap. 
     The immersion liquid  12  having entered the gap pools in the gap if nothing is done. The pooled immersion liquid  12  could be scattered on the wafer  5  or on the support plate  121  when the wafer stage  70  moves. 
     When the immersion liquid  12  remaining on the wafer  5  or the support plate  121  evaporates, the wafer  5  or the support plate  121  is deformed by the vaporization heat, and a water mark is thus formed on the wafer  5  or on the support plate  121 . 
     Therefore, the immersion illiquid  12  pooled in the gap between the support plate  121  and the wafer  5  is conventionally sucked and recovered through a recovery path. 
     However, when the immersion liquid  12  pooled in the gap is sucked and recovered, the immersion liquid  12  can evaporate in the recovery path, and the temperature of the support plate  121  can be lowered by the vaporization heat generated when the immersion liquid  12  is evaporated. When the temperature of the support plate  121  lowers, the temperatures of other members of the wafer stage  70  also lower. As a result, the wafer stage  70  is deformed, and the positioning precision the wafer stage  70  lowers. 
     Japanese Patent Application Laid-Open No. 2007-194618 discusses that the support plate  121  includes a temperature-regulating path for preventing the lowering of the temperature of the support plate  121 . 
     Japanese Patent Application Laid-Open No. 2006-313910 discusses an immersion exposure apparatus, which supplies a liquid into the gap between the wafer  5  and the support plate  121  for removing bubbles. The pamphlet of International Publication No. 2006/112436 discusses an exposure apparatus in which a temperature-regulating liquid is supplied into the nozzle unit  11  for preventing the effect of the vaporization heat in a recovery path of the nozzle unit  11 . 
     In Japanese Patent Application Laid-Open No. 2007-194618, only the temperature of the support plate  121  is regulated. However, the recovery path passes through not only the support plate  121  but also other members of the wafer stage  70 . Therefore, in addition to the temperature of the support plate  121 , the temperatures of other members of the wafer stage  70  need to be regulated to suppress the lowering the temperature of the wafer stage  70 . 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an exposure apparatus advantageous in a stability of temperature of a stage including a recovery path of an immersion liquid. 
     According to an aspect of the present invention, an exposure apparatus for exposing a substrate to light via an immersion liquid includes a stage configured to hold the substrate and to be moved, and the stage includes a chuck configured to hold the substrate, a support member arranged around the chuck, and configured to support the immersion liquid, a recovery path configured to recover the immersion liquid having entered a gap between the substrate and the support member, and a temperature-regulating path through which a temperature-regulated liquid flows, wherein the temperature-regulating path is connected with the recovery path. The above aspect of the present invention can provide, for example, an exposure apparatus advantageous in a stability of temperature of a stage including a recovery path of an immersion liquid. 
     Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a cross-sectional view of a wafer stage according to a first exemplary embodiment of the present invention. 
         FIG. 2  is a top view of a wafer stage according to the first exemplary embodiment of the present invention. 
         FIG. 3  is a cross-sectional view of a wafer stage according to a second exemplary embodiment of the present invention. 
         FIG. 4  is a top view of a wafer stage according to the second exemplary embodiment of the present invention. 
         FIG. 5  is a cross-sectional view of a wafer stage according to a third exemplary embodiment of the present invention. 
         FIG. 6  is a top view of a wafer stage according to the third exemplary embodiment of the present invention. 
         FIG. 7  is a schematic diagram illustrating an example of an exposure apparatus according to an exemplary embodiment of the present invention. 
         FIG. 8  is a cross-sectional view of a wafer stage according to a fourth exemplary embodiment of the present invention. 
         FIG. 9  is a top view of a wafer stage according to a fifth exemplary embodiment of the present invention. 
         FIG. 10  is a schematic diagram of a conventional exposure apparatus. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings. 
       FIG. 7  is a schematic diagram illustrating an example of an exposure apparatus according to an exemplary embodiment of the present invention. An exposure apparatus  100  of the exemplary embodiment is an immersion exposure apparatus exposing a wafer (substrate)  6  to light via an immersion liquid  12 . As illustrated in  FIG. 7 , the exposure apparatus of the exemplary embodiment includes an illumination device  1 , a reticle stage  3 , a projection optical system  4 , a wafer stage  7 , and a nozzle unit  11 . 
     The exposure apparatus  100  of the exemplary embodiment is similar to the conventional exposure apparatus  200  illustrated in  FIG. 10 , but only a configuration of the wafer stage  7  is different. Therefore, the exemplary embodiment of the wafer stage  7  will be described in detail below. 
     A wafer stage of the first exemplary embodiment will be described with reference to  FIGS. 1 and 2 .  FIG. 1  is a cross-sectional view of the wafer stage according to the first exemplary embodiment of the present invention.  FIG. 2  is a top view of the wafer stage according to the first exemplary embodiment of the present invention. 
     A wafer stage  7   a  of this exemplary embodiment includes a wafer chuck  6  and a support plate  21 , as illustrated in  FIG. 1 . The wafer chuck  6  holds the wafer  5  by vacuum suction. 
     The support plate  21  is arranged around the wafer chuck  6 , and supports the immersion liquid  12  and the wafer  5  when an edge shot of the wafer  5  is exposed to light. Thus, the surface of the support plate  21  is set at approximately the same height as the surface of the wafer  5  held by the wafer chuck  6 . 
     The support plate  21  includes an annular interchangeable plate  40 . The interchangeable plate  40  is detachably placed at a contact portion of the support plate  21  and the immersion liquid  12 . The interchangeable plate  40  is interchanged when the interchangeable plate  40  is soiled. 
     The wafer stage  7   a  includes a recovery path and a temperature-regulating path  26 . The recovery path includes a buffer space  22 , a recovery space  24 , and a recovery pipe  25 . The immersion liquid  12  having entered a gap between the wafer  5  and the support plate  21  (the interchangeable plate  40 ) flows in the recovery path. 
     The nozzle unit  11  includes a supply port  15  and a recovery port  16 . The supply port  15  supplies the immersion liquid  12  to between the projection optical system  4  and the wafer  5 . The recovery port recovers the immersion liquid  12  from between the projection optical system  4  and the wafer  5 . 
     As illustrated in  FIG. 1 , when the edge shot of the wafer  5  is exposed to light, the immersion liquid  12  exists on the gap between the support plate  21  and the wafer  5 . A part of the immersion liquid  12  on the gap enters the gap, and drops to the buffer space  22 . 
     The immersion liquid  12  pooling in the buffer space  22  passes through an aperture  28  of a partition plate  23 , and flows in the recovery space  24 . The immersion liquid  12  having flowed in the recovery space  24  flows into the recovery pipe  25 . The recovery pipe  25  is connected with a suction pump (vacuum pump) (not illustrated), and the immersion liquid  12  is discharged from the exposure apparatus  100 . 
     The buffer space  22  and the recovery space  24  are formed annularly to surround the circular chuck  6 . The partition plate  23  for making a pressure difference is arranged between the buffer space  22  and the recovery space  24 . A plurality of annular apertures  28  is formed on the partition plate  23  at predetermined intervals, and penetrate the partition plate  23 . 
     A shape of the aperture  28  can be a circular shape or a slit shape, as illustrated in  FIG. 2 . A porous member can be fit to the aperture  28 , and a material of the partition plate  23  can be a porous member without forming the aperture  28 . In addition, the partition plate  23  is formed annularly to surround the chuck  6 . 
     The positional relationship between the wafer stage  7   a  and the immersion liquid  12  (the projection optical system  4 ) when the wafer  5  is exposed to light will be described with reference to  FIG. 2 . 
     As illustrated in  FIG. 2 , the immersion liquid  12  relatively moves to the wafer stage  7   a  in order from an area A to an area C, from the area C to an area B, from the area B to an area D, and from the area D to an area E by moving the wafer stage  7   a,  and a plurality of shots on the wafer  5  are thus sequentially exposed to light. 
     When the immersion liquid  12  exists in the area A, the immersion liquid  12  exists on the gap between the wafer  5  and the support plate  21 . At this time, the immersion liquid  12  enters the gap under the area A, and the immersion liquid  12  is supplied to the recovery path (the buffer space  22 , the recovery path  24 , and the recovery pipe  25 ). 
     Similarly, when the immersion liquid  12  exists in the area C, the area D, or the area E, the immersion liquid  12  enters the gap under the area C, the area D, or the area E, and the immersion liquid  12  is supplied to the recovery path. 
     However, when the immersion liquid  12  exists in the area B, the immersion liquid  12  does not exist on the gap between the wafer  5  and the support plate  21 . Thus, the immersion liquid  12  is not supplied to the recovery path. When a state in which the immersion liquid  12  is supplied changes to a state in which the immersion liquid  12  is not supplied, the immersion liquid  12  adheres to a wall face of the recovery path and remains. 
     In such a state, when the suction pump (vacuum pump) continuously sucks, a gas flows on the surface of the immersion liquid  12  adhering to the wall face of the recovery path, and the evaporation of the immersion liquid  12  thus accelerates. Therefore, the temperature of the recovery path greatly lowers due to effect of the vaporization heat, and the temperature of the wafer stage  7   a  lowers. 
     Accordingly, while the wafer  5  is exposed to light, flowing of the immersion liquid  12  in the recovery path and not flowing therein are alternately repeated. Thus, the effect of the vaporization heat increases. 
     Therefore, in the wafer stage  7   a  of the present exemplary embodiment, the temperature-regulating path  26  is connected with the recovery space  24  of the recovery path, and the temperature-regulated liquid constantly flows in the recovery path. The temperature-regulated liquid, which is regulated at a predetermined temperature by a liquid temperature-regulating device  27 , is supplied to the temperature-regulating path  26  through a temperature-regulated pipe  29 . 
     The liquid temperature-regulating device  27  regulates a temperature of the temperature-regulated liquid so that the temperature of the temperature-regulated liquid is the same as the temperature of the immersion liquid  12 , or higher than the temperature of the immersion liquid  12  considering the lowering of the temperature of the wafer stage  7   a  due to the vaporization heat. In addition, as for the temperature-regulated liquid, the same liquid as the immersion liquid  12  can be properly used. 
     In the wafer stage  7   a  of the present exemplary embodiment, the temperature-regulated liquid is constantly supplied to the recovery space  24 . Thus, a liquid constantly flows in the recovery space  24  and the recovery pipe  25 , and the liquid evaporation can be thus suppressed. As a result, the lowering of the temperature of the wafer stage  7   a  can be suppressed. 
     In the present exemplary embodiment, the temperature-regulating path  26  is connected with the recovery pipe  25  on the opposite side of the chuck  6 . However, the temperature-regulating path  26  can be connected with any other position if the temperature-regulated liquid flows in the entire path of the recovery space  24 . 
     The exposure apparatus  100  can suppress the liquid evaporation in the recovery pipe  25  by connecting the temperature-regulating path  26  to the recovery pipe  25  and supplying the temperature-regulated liquid from the recovery pipe  25 , so that the lowering of the temperature of the wafer stage  7   a  can be suppressed 
     The temperature liquid can be supplied only when the immersion liquid  12  exists in the area B and does not exist on the gap between the wafer  5  and the support plate  21 . Even when such a control is performed, the immersion liquid  12  or the temperature-regulated liquid constantly flows in the recovery path. Thus, the liquid evaporation in the recovery path can be suppressed, and the lowering of the temperature of the wafer stage  7   a  can be suppressed. 
     A wafer stage according to a second exemplary embodiment of the present invention will be described with reference to  FIGS. 3 and 4 .  FIG. 3  is a cross-sectional view of the wafer stage of the second exemplary embodiment.  FIG. 4  is a top view of the wafer stage of the second exemplary embodiment. 
     A wafer stage  7   b  of the present exemplary embodiment is different from the wafer stage  7   a  of the first exemplary embodiment about the point of including an annular temperature-regulating path  30  and connection path  31  in a support plate  21 . 
     As illustrated in  FIG. 4 , the temperature-regulating path  30  is formed annularly to surround the wafer chuck  6 . The liquid temperature-regulating device  27  supplies the temperature-regulated liquid, which is regulated at a predetermined temperature, to the temperature-regulating path  30  through the temperature-regulated pipe  29 . 
     The temperature of the temperature-regulated liquid can be the same as a temperature of an immersion liquid  12 , or can be higher than the temperature of the immersion liquid  12  considering the lowering of the temperature of the support plate  21  or the wafer stage  7   b  due to the vaporization heat. 
     The temperature-regulated liquid having flowed in the temperature-regulating path  30  goes around an inside of the support plate  21 , and is discharged from the temperature-regulating path  30 , as illustrated in  FIG. 4 . 
     The connection path  31  connects the temperature-regulating path  30  and the recovery space  24 . A part of the temperature-regulated liquid flowing in the temperature-regulating path  30  can be constantly supplied to the recovery space  24  through the connection path  31  by providing the connection path  31 . 
     Therefore, the temperature-regulated liquid supplied by the liquid temperature-regulating device  27  not only regulates the temperature of the support plate  21 , but also suppresses the liquid evaporation in the recovery space  24  and the recovery pipe  25 , and also suppresses the lowering of the temperature of the wafer stage  7   b.    
     In the present exemplary embodiment, the connection path  31  connects the recovery space  24  and the temperature-regulating path  30 . However, the connection path  31  can connect the recovery pipe  25  and the temperature-regulating path  30 . Even when having such a configuration, the exposure apparatus  100  can regulate the liquid evaporation in the recovery pipe  25 , and can suppress the lowering of the temperature of the wafer stage  7   b.    
     Further, the connection path  31  can include a valve. The valve can supply the temperature-regulated liquid to the recovery path only when the immersion liquid  12  exists in the area B and does not exist on the gap between the wafer  5  and the support plate  21 . 
     Furthermore, a plurality of connection paths  31  can be formed for connecting the recovery space  24  and the temperature-regulating path  30 . 
     A wafer stage of a third exemplary embodiment will be described with reference to  FIGS. 5 and 6 .  FIG. 5  is a cross-sectional view of a wafer stage of the third exemplary embodiment.  FIG. 6  is a top view of the wafer stage of the third exemplary embodiment. 
     A wafer stage  7   c  of the present exemplary embodiment is different from the wafer stage  7   b  of the second exemplary embodiment about the point of including a connection path  32  instead of the connection path  31 . 
     The connection path  32  connects the temperature-regulated pipe  30  and the buffer space  22 . Apart of the temperature-regulated liquid in the temperature-regulating path  30  is constantly supplied to the buffer space  22  through the connection path  32  by providing the connection path  32 . 
     Therefore, the temperature-regulated liquid supplied by the liquid temperature-regulating device  27  not only regulates the temperature of the support plate  21 , but also suppresses the liquid evaporation in the buffer space  22 , the partition plate  23 , the recovery space  24 , and the recovery pipe  25 , and suppresses the lowering of the temperature of the wafer stage  7   c.    
     As illustrated in  FIG. 6 , the connection path  32  includes a plurality of paths arranged corresponding to the positions of the plurality of the apertures  28 . By having this configuration, a gas and a liquid constantly can flow in the plurality of the apertures  28 , and thus the liquid evaporation in the recovery path, which is after the plurality of the apertures, can be suppressed. 
     In addition, the connection path  32  can include a valve. The valve can supply the temperature-regulated liquid to the recovery path only when the immersion liquid  12  exists in the area B and does not exist on the gap between the wafer  5  and the support plate  21 . 
     A wafer stage of a fourth exemplary embodiment of the present invention will be described with reference to  FIG. 8 .  FIG. 8  is a cross-sectional view of the wafer stage of the fourth exemplary embodiment. 
     A wafer stage  7   d  of the present exemplary embodiment is different from the wafer stage  7   a  of the first exemplary embodiment about the points of including a temperature-regulating path  33  instead of the temperature-regulating path  26  and omitting the portion plate  23  and the recovery space  24  in the recovery path. 
     The liquid temperature-regulating device  27  supplies the temperature-regulated liquid, which is regulated at a predetermined temperature, to the temperature-regulating path  33  through the temperature-regulated pipe  29 . The temperature-regulating path  33  is connected with the recovery pipe  25  of the recovery path. 
     By having this configuration, since the temperature-regulated liquid can be constantly supplied in the recovery pipe  25 , sucking only a gas through the recovery pipe  25  is prevented. Thus, the exposure apparatus  100  can suppress the liquid evaporation, and can suppress the lowering of the temperature of the wafer stage  7   d.    
     In the present exemplary embodiment, the temperature-regulating path  33  is connected with the recovery pipe  25 . However, the temperature-regulating path  33  can be connected with the buffer space  22 . By having this configuration, the exposure apparatus  100  can suppress the liquid evaporation in the buffer space  22  and the recovery pipe  25 , and can suppress the lowering of the temperature of the wafer stage  7   d.  In this configuration, the temperature-regulating path  33  can include a plurality of paths, and the plurality of the paths can be connected with the buffer space  22 . 
     The temperature-regulating path  33  can include a valve. The valve can supply the temperature-regulated liquid to the recovery path only when the immersion liquid  12  exists in the area B and does not exist on the gap between the wafer  5  and the support plate  21 . 
     The wafer stage  7   d  can include an annular temperature-regulating path and connection path at the support plate  21 . This configuration is similar to the configuration of the wafer stage  7   b  of the second exemplary embodiment. 
     A wafer stage according to a fifth exemplary embodiment of the present invention will be described with reference to  FIG. 9 .  FIG. 9  is a top view of the wafer stage of the fifth exemplary embodiment. 
     A wafer stage  7   e  of the present exemplary embodiment is different from the wafer stage  7   a  of the first exemplary embodiment about the point that both a temperature-regulating path and a recovery path is divided into two or more. 
     The wafer stage  7   e  includes four temperature-regulating paths  261  to  264 , and four recovery paths. Therefore, the buffer space  22 , the partition plate  23 , and the recovery space  24  are also respectively divided into four. Each of recovery pipes  251  to  254  is connected with each of four recovery paths  24 . 
     The temperature-regulating paths  261  to  264  are connected with the four recovery spaces  24  respectively. 
     When the immersion liquid  12  exists on the gap between the wafer  5  and the support plate  21  due to the movement of the wafer stage  7   e,  the immersion liquid  12  enters one or two of the four recovery paths. For example, as illustrated in  FIG. 9 , when the positional relationship between the wafer stage  7   e  and the immersion liquid  12  comes to be a relationship illustrated with L, the immersion liquid  12  enters two of the four recovery paths. 
     In such a case, the wafer stage  7   e  of the present exemplary embodiment recovers the liquid only by the recovery pipes  251  and  254 , and does not recover the liquid by the other recovery pipes  252  and  253 . Further, as for the temperature-regulated liquid, the wafer stage  7   e  supplies the temperature-regulated liquid only from the temperature-regulating paths  261  and  264 , and does not supply the temperature-regulated liquid from the other temperature-regulating paths  262  and  263 . 
     By having this configuration, since the temperature-regulated liquid is supplied to the recovery paths actually recovering the immersion liquid among the four recovery paths, sucking only a gas through the recovery paths is prevented. Therefore, the exposure apparatus  100  can suppress the liquid evaporation, and can suppress the lowering of the temperature of the wafer stage  7   e.  Since the recovery path is divided into four, the exposure apparatus  100  can spread the temperature-regulated liquid throughout each portion of the recovery paths, and can thus reduce an amount of the temperature-regulated liquid to be used. 
     Each of the recovery pipes  251  to  254  and each of the temperature-regulating paths  261  to  264  includes a valve. The wafer stage  7   e  recovers the immersion liquid  12  and supplies the temperature-regulated liquid by opening the valves of the recovery pipe and the temperature-regulating path, which are connected with the recovery space  24 , which the immersion liquid  12  enters among the four recovery spaces  24 . The valve is opened and closed by a controller (not illustrated) based on driving data of the wafer stage  7   e.    
     In addition, in the present exemplary embodiment, the temperature-regulating paths  261  to  264  are connected with the recovery space  24 . However, the temperature-regulating paths  261  to  264  can be connected with the buffer space  22  or the recovery pipes  251  to  254 . 
     In the present exemplary embodiment, the wafer stage  7   e  includes the temperature-regulating paths  261  to  264  connected with each of four recovery paths. However, if the exposure apparatus  100  can be controlled to suck the immersion liquid  12  in the recovery path, where the immersion liquid  12  enters and flows, among the four recovery paths, the wafer stage  7   e  does not need to include the temperature-regulating paths  261  to  264 . 
     Further, the wafer stage  7   e  can include an annular temperature-regulating path and connection path at the support plate  21 , like the wafer stage  7   b  of the second exemplary embodiment. 
     Next, a method of manufacturing a device (semiconductor device, liquid crystal display device, etc.) as an embodiment of the present invention is described. 
     The semiconductor device is manufactured through a front-end process in which an integrated circuit is formed on a wafer, and a back-end process in which an integrated circuit chip is completed as a product from the integrated circuit on the wafer formed in the front-end process. The front-end process includes a step of exposing a wafer with a photoresist coated thereon to light using the above-described exposure apparatus of the present invention, and a step of developing the exposed wafer. The back-end process includes an assembly step (dicing and bonding), and a packaging step (sealing). 
     The liquid crystal display device is manufactured through a process in which a transparent electrode is formed. The process of forming a transparent electrode includes a step of coating a photoresist on a glass substrate with a transparent conductive film deposited thereon, a step of exposing the glass substrate with the photoresist coated thereon to radiant energy (light, x-ray, charged-particle beam, etc.) using the above-described exposure apparatus, and a step of developing the exposed glass substrate. 
     The device manufacturing method of this embodiment has an advantage, as compared with a conventional device manufacturing method, in at least one of performance, quality, productivity, and production cost of a device. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures, and functions. 
     This application claims priority from Japanese Patent Application No. 2008-291104 filed Nov. 13, 2008, which is hereby incorporated by reference herein in its entirety.