Patent Publication Number: US-2006017909-A1

Title: Stage apparatus, exposure apparatus, and semiconductor device manufacturing mehtod

Description:
This application is a continuation application of copending U.S. patent application Ser. No. 10/704,638, filed Nov. 12, 2003. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to a stage apparatus, an exposure apparatus, and a semiconductor device manufacturing method.  
     BACKGROUND OF THE INVENTION  
      In recent years, the semiconductor industry has been changing and progressing very fast. Accordingly, a semiconductor manufacturing apparatus that can further shrink the feature size and improve the throughput of elements has been sought. To meet the demand for a smaller element feature size, the numerical aperture (NA) of the projection lens has been increased. To manufacture high-performance elements with high productivity, an increase in the diameter of the substrate and the like have been performed.  
      For example, currently, an exposure system having two stages has been proposed to improve the throughput and alignment accuracy. This is an exposure system that transports and transfers a whole substrate holding unit between two stages as it holds a substrate. More specifically, according to this exposure system, alignment is performed at the first stage, and exposure is preformed at the second stage different from the first stage during alignment. This makes it possible to ensure high-accuracy alignment time and improve the throughput.  
      To ensure the superiority of this system, first, the reproducibility of the surface of the substrate holding unit on different stages must be ensured reliably. More specifically, the substrate holding unit must be held between the first stage (alignment stage) and second stage (exposure stage) without changing the surface state of the substrate holding unit, e.g., the surface accuracy, distortion, or the like. Furthermore, the substrate holding unit must be moved between the stages quickly and must be stationarily held on or removed from a support surface for the substrate holding unit instantaneously.  
      In general, however, when the substrate holding unit and a support surface for it are to be brought into total contact with each other, it is difficult to stationarily hold the substrate holding unit on the support surface or to remove it from the support surface instantaneously. The substrate holding unit is highly likely to conform to the shape of the support surface for it. To reliably, stationarily hold the substrate holding unit, after it has moved from a stage, on the support surface for it, the substrate holding unit needs a stationary fixing force that can withstand stage driving. To ensure reproducibility of the surface of the substrate holding unit at the second stage different from the first stage, when the substrate holding unit is to be moved between the stages or is to be stationarily held on or removed from the support surface for it, a power that changes the surface of the substrate holding unit should not be applied to the substrate holding unit. In a conventional exposure system, however, when the substrate holding unit is to be moved between the stages or is to be stationarily held on or removed from the support surface for it instantaneously, it is difficult to ensure the reproducibility of the surface of the substrate holding unit on different stages without changing the surface of the substrate holding unit.  
     SUMMARY OF THE INVENTION  
      The present invention has been made in view of the above problems, and has as its object to improve the throughput.  
      The first aspect of the present invention relates to a stage apparatus, having a substrate holding unit which chucks and holds a substrate, comprising a flat surface having a recess where the substrate holding unit is to be mounted, and a fixing member which fixes a projection support provided to the substrate holding unit onto the flat surface, wherein the substrate holding unit is supported by the fixing member while a distal end of the projection support is in contact with the recess of the flat surface and a remaining portion of the substrate holding unit is not in contact with the flat surface.  
      According to a preferred embodiment of the present invention, the fixing member preferably has a mechanism which applies no moment force to the projection support.  
      According to a preferred embodiment of the present invention, the recess is preferably a V-shaped groove, and the projection support preferably comes into point contact with the V-shaped groove at a distal end thereof.  
      According to a preferred embodiment of the present invention, the projection support preferably comprises at least three projection supports and the fixing member fixing the projection supports, respectively.  
      According to a preferred embodiment of the present invention, the projection support and the fixing member preferably form one component.  
      According to a preferred embodiment of the present invention, the fixing member is preferably fixed to the projection support.  
      According to a preferred embodiment of the present invention, the fixing member can preferably tilt freely at a contact portion with the projection support in an axial direction of the projection support and in a planar direction.  
      According to a preferred embodiment of the present invention, a small gap is preferably present between the projection support and the fixing member, and the projection support can preferably tilt freely in an axial direction of the projection support and in a planar direction because of the gap.  
      According to a preferred embodiment of the present invention, the fixing member preferably has one of a circular shape, an elliptical shape, a shape similar to an ellipse, or a polygonal shape.  
      According to a preferred embodiment of the present invention, the fixing member can preferably elastically deform.  
      According to a preferred embodiment of the present invention, the fixing member preferably has an outer seal portion on an outer surface thereof, and the outer seal portion preferably comes into contact with the flat surface to define a closed space.  
      According to a preferred embodiment of the present invention, a seal number is preferably arranged between the projection support and the fixing member.  
      According to a preferred embodiment of the present invention, the V-shaped groove is preferably formed to extend in three directions on the flat surface at an angular interval of about 120°.  
      According to a preferred embodiment of the present invention, the stage apparatus preferably has a chucking/holding mechanism which chucks and holds the projection support onto the flat surface.  
      According to a preferred embodiment of the present invention, the stage apparatus preferably has a chucking/holding mechanism which chucks and holds the projection support onto the substrate holding unit.  
      According to a preferred embodiment of the present invention, the projection support can preferably be removed from the flat surface by canceling a chucking/holding force from the chucking/holding mechanism.  
      According to a preferred embodiment of the present invention, the projection support can preferably be removed from the substrate holding unit by canceling a chucking/holding force from the chucking/holding mechanism.  
      According to a preferred embodiment of the present invention, the chucking/holding mechanism preferably uses one of a negative pressure, a Coulomb force, and a magnetic force.  
      The second aspect of the present invention relates to a stage apparatus, having a substrate holding unit which chucks and holds a substrate, comprising a flat surface having a projection support where the substrate holding unit is to be mounted, and a fixing member which fixes the projection support provided to the flat surface with a recess formed in the substrate holding unit, wherein the substrate holding unit is supported by the fixing member while the recess of the substrate holding unit is in contact with a distal end of the projection support and a remaining portion of the substrate holding unit is not in contact with the flat surface.  
      The third aspect of the present invention relates to an exposure apparatus comprising an optical system which projects exposure light irradiating a master having a pattern onto a substrate, and a stage apparatus having a substrate holding unit which holds the substrate or master, wherein the stage apparatus includes a stage, a flat surface which drives the substrate holding unit within a predetermined plane, and a fixing member which fixes a projection support formed on the substrate holding unit onto the flat surface, and the substrate holding unit is supported while a distal end of the projection support is in contact with the flat surface and the substrate holding unit is not in contact with the flat surface.  
      The fourth aspect of the present invention relates to a semiconductor device manufacturing method comprising an applying step of applying a photosensitive material on a substrate, an exposure step of transferring a pattern onto the substrate, applied with the photosensitive material in the applying step, by utilizing the exposure apparatus, and a developing step of developing the photosensitive material on the substrate where the pattern has been transferred in the exposure step.  
      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 through 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.  
       FIG. 1  is a view showing a stage apparatus according to a preferred embodiment of the present invention;  
       FIG. 2  is an enlarged view of a portion in the vicinity of a projection support for a wafer chuck;  
       FIG. 3  is a view showing the arrangement of V-grooves on a wafer chuck support surface;  
       FIG. 4  is a view of a portion including a fixing member which ensures a wide surface area where a suction force acts;  
       FIG. 5  is a view of a portion in which a fixing member, which ensures a wide surface area where a suction force acts, is a different component;  
       FIG. 6  is an enlarged view of a portion in the vicinity of a projection support for a wafer chuck;  
       FIG. 7  is an enlarged view of a portion in the vicinity of a projection support for a wafer chuck;  
       FIGS. 8A and 8B  are enlarged views of a portion in the vicinity of a projection support for a wafer chuck;  
       FIGS. 9A and 9B  are enlarged views of a portion in the vicinity of a projection support for a wafer chuck;  
       FIGS. 10A and 10B  are enlarged views of a portion in the vicinity of a projection support for a wafer chuck;  
       FIGS. 11A and 11B  are enlarged views of a portion in the vicinity of a projection support for a wafer chuck;  
       FIGS. 12A and 12B  are enlarged views of a portion in the vicinity of a projection support for a wafer chuck;  
       FIG. 13  is a conceptual view showing the arrangement of an exposure apparatus according to a preferred embodiment of the present invention;  
       FIG. 14  is a flow chart showing the flow of an overall semiconductor device manufacturing process; and  
       FIG. 15  is a flow chart showing the detailed flow of the wafer process.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
     First Embodiment  
      A stage apparatus according to the first preferred embodiment of the present invention will be described in detail.  
       FIG. 1  is a schematic view showing the stage apparatus according to the preferred embodiment of the present invention. This stage apparatus has a flat surface  13  for driving a substrate holding unit (wafer chuck)  9  within a predetermined plane, and a fixing member  14  for fixing a projection support  11  formed on the substrate holding unit  9  onto the flat surface  13 . The substrate holding unit  9  is supported while the distal end of the projection support  11  is in contact with a recess (V-groove)  12  of the flat surface  13  and the main body of the substrate holding unit  9  is not in contact with the flat surface (wafer chuck support surface)  13 . With this arrangement, the stage apparatus according the preferred embodiment of the present invention drives the substrate holding unit  9  which chucks and holds a substrate.  
      The wafer chuck  9  has a pin-shaped projection (not shown) interspersed on its support surface where a wafer  8  (see  FIG. 13 ) as a substrate is to be placed. The wafer  8  is placed on the surfaces of the projections, and is held flat by a negative pressure or a Coulomb force. The wafer chuck  9  also has the projection support  11  for supporting the wafer chuck  9  on its surface opposite to the support surface where the wafer  8  is to be placed. The wafer chuck support surface  13  for placing the wafer chuck  9  has the fixing member  14 , which supplies a force to only the projection support  11  with a chucking/holding force. The projection support  11  and the wafer chuck  9  may form one component, or separate components. As the chucking/holding force, a negative pressure, a Coulomb force, a magnetic force, or the like, is preferably used.  
      The stage apparatus, according to the preferred embodiment of the present invention, is characterized in the following respects. Namely, as shown in  FIG. 1 , the wafer chuck  9  is supported through the projection support  11 , the distal end of the projection support  11  to come into contact with the wafer chuck support surface  13  is spherical, and the V-groove  12  is formed in the wafer chuck support surface  13 , so that the projection support  11  and the V-groove  12  of the wafer chuck support surface  13  come into point contact with each other. The stage apparatus is also characterized in that the chucking/holding force acting on the fixing member  14  fixes only the projection support  11 .  
       FIG. 2  is an enlarged view of a portion in the vicinity of the projection support  11  for the wafer chuck  9 . In  FIG. 2 , if there are three projection supports, the wafer chuck  9  is held at six points. As the projection support  11  and the V-groove  12  are in point contact with each other, no moment force is generated at the contact portion. The fixing member  14  also has a mechanism that applies no moment force to the projection support  11 . The projection support  11  comes into contact with the V-groove  12  at a plurality of points (in this case, two points per projection support), so that the force acting on the projection support  11  can be dispersed. Therefore, deformation caused by contact stress is largely decreased when compared to a case wherein the projection support  11  is in contact with the V-groove  12  at one point. Since the contact area is small, dust is caught in the contact area at a low possibility.  
      Although the V-groove  12  of this embodiment has a V shape, the present invention is not limited to this. For example, any V-groove  12  will do as long as it is formed of two surfaces including an inclined surface and the projection support  11  slides on it by the weight of the wafer chuck  9  so that the position of the projection support  11  is determined. The open angle formed by the two surfaces may be 90°, or more than that, or less than that. The projection support  11 , which comes into contact with the V-groove  12  of the wafer chuck support surface  13 , preferably has a shape (e.g., a spherical shape) with which the contact portion of projection support  11  and the V-groove  12  of the wafer chuck support surface  13  forms point contact. If the moment force is small, the projection support  11  and wafer chuck support surface  13  may be formed to come into linear contact or surface contact with each other.  
      In this embodiment, the wafer chuck  9  has the projection support  11 , and the V-groove  12  is formed on a stage  10 . However, the present invention is not limited to this. For example, the relationship between the projection support  11  on the lower surface of the wafer chuck  9  and the V-groove  12  can be reversed. More specifically, the projection support  11  may be formed on the wafer chuck support surface  13 , and the V-groove  12  may be formed in the lower surface of the wafer chuck  9 . In this case, the projection support  11  for supporting the wafer chuck  9  is fixed to the wafer chuck  9 . When the chucking/holding force is canceled, the projection support  11  can be released from the wafer chuck support surface  13 . The projection support  11  for supporting the wafer chuck  9  may be fixed to the wafer chuck support surface  13 . When the chucking/holding force is canceled, the projection support  11  can be released from the wafer chuck  9 .  
     Second Embodiment  
      A stage apparatus according to the second preferred embodiment of the present invention is characterized in the following respects. Namely, as shown in  FIG. 3 , in an X-Y stage apparatus including a wafer chuck  9 , which chucks and holds a wafer  8  by suction, caused by a negative pressure or a Coulomb force, the surface of the wafer chuck  9  is supported on a wafer chuck support surface  13  at three points, so that the surface of the wafer chuck  9  is supported stably.  
      The wafer chuck  9  has three projection supports  11 . As shown in  FIG. 3 , V-grooves  12  for receiving the respective projection supports  11  are arranged on the wafer chuck support surface  13  in three directions at an angular interval of about  1200 . The position of the wafer chuck  9  is uniquely determined by its own weight. Hence, an abutment which is indispensable for positioning becomes unnecessary, and the reproducibility of the support position can be increased. When the wafer chuck  9  is supported and retained at three points, the wafer chuck  9  can be fixed stably. Also, as the wafer chuck  9  is supported at three points, the wafer chuck  9  conforms to the shape of the wafer chuck support surface  13  at a lower possibility compared to a case wherein the wafer chuck  9  is supported at its entire surface. Also, the possibility that distortion, heat, or vibration, which occurs on the wafer chuck support surface  13  in various manners during exposure or movement of the wafer chuck  9 , adversely affect deformation, or the like, of the wafer chuck  9 , decreases.  
      As described above, that the V-grooves  12  are arranged in three directions at an angular interval of about 120° and that the projection supports  11  and the V-grooves  12  of the wafer chuck support surface  13  come into point contact with each other are very effective to stably support the wafer chuck  9 .  
      A fixing member  14 , which holds the projection support  11  against the wafer chuck support surface  13  with a force that chucks and holds the wafer chuck  9  can define a closed space, when an outer seal portion present on its outer surface comes into contact with the wafer chuck support surface  13  with no gap. The fixing member  14  preferably has one of a circular shape, an elliptical shape, a shape similar to an ellipse, or a polygonal shape. The chucking/holding force acting on the fixing member  14  is preferably one of a negative pressure, a Coulomb force, and a magnetic force. When the chucking/holding force is a negative pressure, a closed space is needed. The suction force is obtained by vacuum (e.g., evacuation with a vacuum pump) from a vacuum hole (not shown) in the closed space defined by the fixing member  14  and wafer chuck support surface  13 .  
      When leakage is prevented in the above manner, the projection support  11  can be chucked reliably to the wafer chuck support surface  13 . The outer seal portion present on the outer surface of the projection support  11  can be incorporated in the following embodiments as well.  
     Third Embodiment  
      A stage apparatus according to the third preferred embodiment of the present invention includes a wafer chuck  9 , which chucks and holds a wafer  8  with suction caused by a negative pressure or the Coulomb force, as shown in  FIG. 4 . A projection support  11 , which supports the wafer chuck  9  and comes into contact with a V-groove  12 , forms one component together with a fixing member  14 . The projection support  11  to come into contact with the V-groove  12  is not limited to the one which forms one component together with the fixing member  14 . For example, as shown in  FIG. 5 , the projection support  11  may be fixed to a fixing member  14  as a separate component.  
     Fourth Embodiment  
      A stage apparatus according to the fourth preferred embodiment of the present invention has a wafer chuck  9 , which chucks and holds a wafer  8  by suction caused by a negative pressure or a Coulomb force. To prevent deformation of the surface of the wafer chuck  9 , which is caused by the shape of a wafer chuck support surface  13 , in this stage apparatus, a projection support  11  for supporting the wafer chuck  9  has an arrangement for absorbing or avoiding deformation.  
      In the stage apparatus according to this embodiment, a fixing member  14  can tilt freely at its contact portion in the axial direction of the projection support  11  and in the planar direction. When the fixing member  14  has the above degrees of freedom at its contact portion, a small gap is present at the contact portion of the projection support  11  and fixing member  14 . This small gap allows the fixing member  14  to move freely.  
      When the projection support  11  has a fixing member  14  with a shape that ensures a wide surface area parallel to the wafer chuck support surface  13 , the fixing member  14  can move freely at the contact portion with respect to the projection support  11 .  
      As an example of the above arrangement, for example, in the stage apparatus according to this embodiment, as shown in  FIG. 6 , the fixing member  14  has a small gap  15  at the contact portion with respect to the projection support  11 . This gap  15  allows the projection support  11  to move freely to a certain degree. The gap  15  has such a size that, when the fixing member  14  inclines with respect to the projection support  11 , the projection support  11  will not come into contact with the fixing member  14  with this inclination. This arrangement can be applied to the following fifth to ninth embodiments as well.  
     Fifth Embodiment  
      A stage apparatus according to the fifth embodiment of the present invention has a fixing member  14  which holds only a projection support  11  for a wafer chuck  9  with respect to a wafer chuck support surface  13 . As shown in  FIG. 7 , the fixing member  14  can elastically deform by a chucking/holding force as a negative pressure. In this case, the fixing member  14  is preferably designed with such a thickness that it can elastically deform by the suction force. This arrangement can be one in which an elastic body or a variable-length material is incorporated in the projection support  11 , or one in which a variable-length mechanism is incorporated in the projection support  11 . When the fixing member  14  comes into contact with the wafer chuck support surface  13  and is chucked and held, the fixing member  14  is tilted to conform to the stage of the wafer chuck support surface  13  at a high possibility. This, however, does not adversely affect the projection support  11  with a moment force or the like. This is because the moment force or the like is absorbed by the contact portion of the fixing member  14  with respect to the projection support  11 , or by the elastic deformation of the fixing member  14  serving as the elastic body.  
     Sixth Embodiment  
      A stage apparatus according to the sixth preferred embodiment of the present invention is characterized in that, as shown in  FIGS. 8A and 8B , a fixing member  14  incorporates a rolling mechanism  16  at its contact portion with respect to a projection support  11 , so that the fixing member  14  can move freely with respect to the projection support  11 . As the projection support  11  can vertically move smoothly with respect to the fixing member  14 , the projection support  11  can be reliably chucked to a wafer chuck support surface  13  without any moment force from the fixing member  14 .  
     Seventh Embodiment  
      A stage apparatus according to the seventh preferred embodiment of the present invention is characterized in that, as shown in  FIGS. 9A and 9B , a fixing member  14  incorporates a vertical slide mechanism  17  at its contact portion with respect to a projection support  11 , so that the fixing member  14  can move freely with respect to the projection support  11  in the axial direction of the projection support  11 . The vertical slide mechanism  17  is characterized in that it reduces frictional resistance, so that its contact area is small and its contact surface is smooth. Thus, the projection support  11  can be reliably chucked to a wafer chuck support surface  13  without any moment force from the fixing member  14 .  
     Eighth Embodiment  
      A stage apparatus according to the eighth preferred embodiment of the present invention is characterized in that, as shown in  FIGS. 10A and 10B , a fixing member  14  incorporates, at its contact portion with respect to a projection support  11 , a vertical slide mechanism  17 ′ having no contact portion, so that a projection support  11  can move freely with respect to the fixing member  14 . For example, when the projection support  11  is fixed to the fixing member  14  with springs  18 , or the like, the projection support  11  can be reliably chucked to a wafer chuck support surface  13  without any moment force from the fixing member  14 .  
     Ninth Embodiment  
      A stage apparatus according to the ninth preferred embodiment of the present invention is characterized in that, as shown in  FIGS. 11A and 11B , an elastic body  19  is provided at that portion of a projection support  11 , which comes into contact with a fixing member  14 , so that the projection support II can move freely. Thus, the projection support  11  can be reliably chucked to a wafer chuck support surface  13  without any moment force from the fixing member  14 .  
     Tenth Embodiment  
      A stage apparatus according to the tenth preferred embodiment of the present invention is characterized in that, as shown in  FIGS. 12A and 12B , a seal member  20  is arranged between a projection support  11  and fixing member  14  within a range not limiting the degrees of freedom. As the seal member  20 , for example, an O-ring is used.  
     Eleventh Embodiment  
      A stage apparatus according to the eleventh preferred embodiment of the present invention includes a wafer chuck  9  which chucks and holds a wafer  8  by suction caused by a negative pressure or the Coulomb force. The wafer chuck  9  is placed on a wafer chuck support surface  13  through a projection support  11  which comes into contact with the wafer chuck support surface  13 , and is chucked and placed by a negative pressure, the Coulomb force, or a magnetic force.  
      Since the wafer chuck  9  must be fixed on the wafer chuck support surface  13 , not only is the wafer chuck  9  placed on the wafer chuck support surface  13 , but also a force is applied to the projection support  11 , which comes into contact with the wafer chuck support surface  13 , thereby fixing the wafer chuck  9 . As this force, a vacuum force, a Coulomb force, a magnetic force, or the like, is used. A mechanism that generates such a force is incorporated in the wafer chuck support surface  13  or the projection support  11 . The mechanism which generates the force includes a mechanism such as a pump for generating a vacuum force, an electrode for generating the Coulomb force, an electromagnet for generating a magnetic force, and the like.  
      As described above, according to the present invention, a large integrated device can be manufactured stably with high productivity. With the stage apparatus according to the preferred embodiment of the present invention and the wafer chuck incorporated in it, the wafer chuck can be stationarily held on and removed from the support surface of the wafer chuck instantaneously. Thus, only the projection support can be held and fixed without applying any forces to the wafer chuck. The reproducibility of the surface of the wafer chuck on different stages can thus be obtained.  
      As described above, with the stage apparatus according to the preferred embodiment of the present invention, problems accompanying the increase in diameter of the wafer, high-speed movement of the wafer chuck, and the like, are solved, so that the throughput can be improved.  
     Other Embodiment  
      [Exposure Apparatus] 
      An example will be described wherein a stage apparatus according to a preferred embodiment of the present invention is applied to a reduction projection exposure apparatus.  
       FIG. 13  is a conceptual view showing the arrangement of an exposure apparatus according to a preferred embodiment of the present invention. As shown in  FIG. 13 , in this exposure apparatus, a reticle  2  as an exposure master is placed on a reticle stage  4 , and is irradiated with exposure light guided from a light source (not shown) through an illumination optical system  1 . The exposure light passing through the reticle  2  is reduced to one-fifth by a projection optical system  5 , to irradiate a silicon substrate (wafer) or a wafer  8  as an object to be processed. As wafer chuck  9  serving as a substrate holding unit for holding the wafer  8  is placed on a stage  10 , which can move the wafer  8  within a horizontal plane.  
      [Exposure Sequence] 
      The exposure sequence of the exposure apparatus will be described. After the wafer  8  as the exposure target is set in the exposure apparatus automatically or manually, the exposure apparatus starts operation upon reception of an exposure start command. First, the wafer  8  is transported onto the wafer chuck  9  placed on the stage  10  by a transport system. Subsequently, a plurality of alignment marks on the wafer  8  are detected and measured by an off-axis scope  7  mounted on the stage  10 . The magnification, rotation, and X-Y error amounts of the wafer  8  are determined, and the position of the wafer  8  is corrected. The stage  10  moves so as so to set the first shot position of the wafer  8  chucked and held by the wafer chuck  9  to coincide with the exposure position. After the first shot position is focused by a surface measuring means  6 , it is exposed for about 0.2 sec. The off-axis scope  7  steps to the second shot position on the wafer  8 , and exposure is sequentially repeated. This sequence is performed repeatedly. When the final shot process is ended, an exposure process for one wafer  8  is completed. The wafer  8  is transferred from the wafer chuck to a recovery transport band, and is returned to the wafer carrier.  
      [Semiconductor Device Manufacturing Process] 
      A semiconductor device manufacturing process utilizing the above exposure apparatus will be described.  FIG. 14  is a flow chart of the flow of the overall semiconductor device manufacturing process. In step  1  (circuit design), circuit design of a semiconductor device is performed. In step  2  (mask fabrication), a mask is fabricated based on the designed circuit pattern. In step  3  (wafer fabrication), a wafer is manufactured by using a material such as silicon. In step  4  (wafer process), called a pre-process, an actual circuit is formed on the wafer by lithography by using the mask and wafer described above. In step  5  (assembly), called a post-process, a semiconductor chip is formed by using the wafer fabricated in step  4 , and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step  6  (inspection), inspections such as the operation confirmation test and durability test of the semiconductor device fabricated in step  5  are performed. After these steps, the semiconductor device is completed, and shipped (step  7 ).  
       FIG. 15  is a flow chart showing the detailed flow of the wafer process. In step  11  (oxidation), the surface of the wafer is oxidized. In step  12  (CVD), an insulating film is formed on the wafer surface. In step  13  (electrode formation), an electrode is formed on the wafer by vapor deposition. In step  14  (ion implantation), ions are implanted in the wafer. In step  15  (resist processing), a photosensitive agent is applied to the wafer. In step  16  (exposure), the circuit pattern is transferred to the wafer by using the above exposure apparatus. In step  17  (development), the exposed wafer is developed. In step  18  (etching), the resist is etched except for the developed resist image. In step  19  (resist removal), an unnecessary resist after etching is removed. These steps are repeated to form multiple circuit patterns on the wafer.  
      As described above, according to the present invention, the throughput can be improved.  
      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.