Abstract:
An exposure apparatus including a projection optical system and configured to expose a substrate to light via the projection optical system includes a support configured to support the projection optical system, an object supported by the support and movable relative the support, an actuator configured to drive the object, a detector configured to detect a relative position between the object and the support, and a controller configured to perform a control of the actuator based on an output of the detector to cause the object to follow the support. The controller is configured to perform an estimation of a vibration of the support based on an output of the detector in parallel with the control to cause the object to follow the support.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an exposure apparatus including a support configured to support a projection optical system and a device manufacturing method using the exposure apparatus. 
     2. Description of the Related Art 
     Conventionally, in processes for manufacturing a semiconductor device including a micropattern, such as a large scale integrated circuit (LSI) or a very large scale integrated circuit (VLSI), a pattern formed on a reticle (mask) is projected onto a substrate with a reduced projection exposure apparatus. Since the substrate is coated with a photosensitive material, the pattern is transferred to the substrate. In order to meet a demand for finer micropatterns that are required in highly-integrated semiconductor devices, resist processes have improved and exposure apparatuses have become capable of handling highly-integrated semiconductor devices. 
     In an exposure apparatus configured to perform micropattern exposure, transmission of a vibration from the floor on which the exposure apparatus is placed to the exposure apparatus can cause deterioration in overlay precision and precision of exposure images. Waiting the vibration to cease, however, will result in lower throughput. Further, vibration tolerance is even more critical for a next-generation exposure apparatus using extreme ultraviolet (EUV) light. 
     Japanese Patent Application Laid-Open No. 3-121328 discusses a technique to reduce such a vibration by measuring vibration of a vibration control base having an acceleration sensor.  FIG. 12  illustrates a configuration discussed in Japanese Patent Application Laid-Open No. 3-121328. 
     A vibration control base  1012  is supported by an air mount  1011 . Air is supplied to the air mount  1011  via a control valve  1015 . An acceleration sensor  1013  is mounted on the vibration control base  1012 . A controller  1014  controls an opening of the control valve  1015  according to an acceleration signal detected by the acceleration sensor  1013 . As a result, the vibration of the vibration control base  1012  is controlled. 
     Further, Japanese Patent Application Laid-Open No. 2005-294790 discusses a configuration in which a vibration transmitted from a first part to a second part is controlled. The first part is clamped to a base arranged on a floor and the second part is clamped to a frame configured to support a projection optical system.  FIG. 13  illustrates the configuration discussed in Japanese Patent Application Laid-Open No. 2005-294790. 
     In  FIG. 13 , a gas spring  73 , which is arranged between a first part  69  and a second part  71 , is configured to control transmission of the vibration. Further, the position of the second part  71  relative to the first part  69  is controlled by a position control system. 
     The position control system includes a reference object  200  supported by the first part  69  via a reference support structure  201  (reference spring), a position sensor  202  mounted on the second part  71 , and an actuator  203  arranged between the first part  69  and the second part  71 . 
     The position sensor  202  detects a distance between the reference object  200  and the position sensor  202 . The actuator  203  is controlled according to a detection signal from the position sensor  202 . 
     However, in a case where a vibration of a supporting member that supports a projection optical system is measured by an acceleration sensor as discussed in Japanese Patent Application Laid-Open No. 3-121328, it is difficult to precisely detect a low-frequency vibration below 1 Hz according to a performance characteristic of the acceleration sensor. 
     On the other hand, in a case where a distance between the reference object  200  supported by the first part  69  and the position sensor  202  supported by the second part  71  is measured as discussed in Japanese Patent Application Laid-Open No. 2005-294790, measurement error may increase due to different ambient environment surrounding the reference object  200  and the position sensor  202 . Here, the ambient environment includes such factors as temperature, humidity, and pressure. 
     Further, if the position of the second part  71 , which is a supporting member that supports the projection optical system, is controlled according to a measurement of the vibration using the position sensor  202  and the reference object  200 , the second part  71  may oscillate according to the natural vibration frequency of the reference spring, which supports the reference object  200 . 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an exposure apparatus that reduces vibration with high accuracy. 
     According to an aspect of the present invention, an exposure apparatus including a projection optical system and configured to expose a substrate to light via the projection optical system includes a support configured to support the projection optical system, an object supported by the support and movable relative the support, an actuator configured to drive the object, a detector configured to detect a relative position between the object and the support, and a controller configured to perform a control of the actuator based on an output of the detector to cause the object to follow the support. The controller is configured to perform an estimation of a vibration of the support based on an output of the detector in parallel with the control to cause the object to follow the support. 
     According to another aspect of the present invention, a method for manufacturing a device includes exposing a substrate to light using the above-described exposure apparatus, developing the exposed substrate, and processing the developed substrate to manufacture the device. 
     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  illustrates an exposure apparatus according to an exemplary embodiment of the present invention. 
         FIG. 2  illustrates a vibration estimation unit according to an exemplary embodiment of the present invention. 
         FIG. 3  is a block diagram illustrating position control for a reference object according to an exemplary embodiment of the present invention. 
         FIG. 4  is a block diagram illustrating position control for a supporting member according to an exemplary embodiment of the present invention. 
         FIG. 5  illustrates vibration isolation ratios obtained when an acceleration sensor is used and when a configuration according to an exemplary embodiment of the present invention is used. 
         FIG. 6  is a block diagram illustrating velocity control for a reference object according to an exemplary embodiment of the present invention. 
         FIG. 7  illustrates a spring element and a damping element arranged between a reference object and a member according to an exemplary embodiment of the present invention. 
         FIG. 8  is a block diagram illustrating position control for a reference object in a case where a spring element and a damping element are arranged between the reference object and a member according to an exemplary embodiment of the present invention. 
         FIG. 9  is a block diagram illustrating velocity control for a reference object in a case where a spring element and a damping element are arranged between the reference object and a member according to an exemplary embodiment of the present invention. 
         FIG. 10  is a flowchart illustrating device manufacturing processes according to an exemplary embodiment of the present invention. 
         FIG. 11  is a detailed flowchart illustrating a wafer process illustrated in  FIG. 10 . 
         FIG. 12  illustrates a conventional vibration control technique using an accelerometer. 
         FIG. 13  illustrates a configuration of a conventional position measuring apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings. 
     First Exemplary Embodiment 
       FIG. 1  illustrates an exposure apparatus according to a first exemplary embodiment of the present invention. 
     An exposure apparatus  100  includes a projection optical system  102  configured to project a pattern onto a wafer  101 , a supporting member  103  configured to support the projection optical system  102 , and a stage apparatus  104  configured to position the wafer  101 . 
     The supporting member  103  is mounted on a base  105  with a vibration isolation mechanism  106  inserted therebetween. The base  105  can be the floor on which the exposure apparatus  100  is placed or can also be a plate member placed on the floor. 
     The supporting member  103  includes a vibration estimation unit  107 . The vibration estimation unit  107  is configured to estimate a vibration of the supporting member  103 . The vibration of the supporting member  103  is, for example, a vibration transmitted from the base  105 . 
     Details of the vibration estimation unit  107  will now be described with reference to  FIG. 2 . The vibration estimation unit  107  includes a member  1  that is fixed to the supporting member  103 , a reference object  2  that is supported to be movable relative to the member  1 , a linear motor  3  (actuator) configured to drive the reference object  2  relative to the member  1 , and a sensor  4  configured to detect a relative position (relative displacement) of the reference object  2  to the member  1 . The member  1  is in a form of a box. 
     The linear motor  3  includes a magnet and a coil. Either the magnet or the coil is fixed to the member  1  while the other is fixed to the reference object  2 . The reference object  2  is supported in a levitated state by a force generated by the linear motor  3 . A drive unit other than a linear motor can also be used for the linear motor  3 . 
     The sensor  4  can be an apparatus including an optical unit, for example, a laser interferometer. The laser interferometer can be a conventional interferometer and a Michelson interferometer, which is discussed in Japanese Patent Application Laid-Open No. 60-174904, for example, can be used. According to the present exemplary embodiment, the sensor  4  detects position displacement in three axial directions, i.e., the x-, y-, and z-axis directions. Although the number of the detection directions may be one, three directions described above or further six directions including the x-, y-, and z-axis directions and their rotational directions ωx, ωy, and ωz can be employed. A plurality of vibration estimation units  107  configured to detect different detection directions can also be used. 
     It is to be noted that the member  1  can be in a form other than the box form. Further, the linear motor  3 , the sensor  4 , and the reference object  2  can be directly supported by the supporting member  103  without the member  1 . 
     The vibration estimation unit  107  further includes a control section  5 , a vibration estimation section  6 , and a memory section  7 . The control section  5  controls the linear motor  3  based on an output from the sensor  4 . According to this control, the reference object  2  can follow the member  1 . The control section  5  is connected to a main control section configured to control the exposure apparatus  100  or is configured integrally with the exposure apparatus  100 . The control section  5  is capable of giving a command to the linear motor  3  depending on a target position of the reference object  2 . 
     The vibration estimation section  6  estimates the vibration of the member  1  based on an output of the sensor  4  when the control section  5  causes the reference object  2  to follow the member  1  and also on a transfer function of follow-up control that is stored in advance in the memory section  7 . Details of a method for estimating the vibration will be described below with reference to  FIG. 3 . 
       FIG. 3  is a block diagram illustrating position control for the reference object  2 . In  FIG. 3 , Rx is a target position of the reference object  2 , Cd(s) is a transfer function of a proportional differential (PD) compensator  207  in the control section  5 , P(s) is a transfer function of the reference object  2  as a controlled object  208 , and Xi is a relative position of the reference object  2  measured by the sensor  4 . The measured relative position Xi is fed back to the target position Rx by the control section  5 . 
     The measured relative position Xi contains a disturbance Xm. Since the disturbance Xm is considered to depend greatly on a vibration of the member  1  (the supporting member  103 ) according to the present exemplary embodiment, this disturbance Xm is estimated as a vibration. 
     If the transfer functions Cd(s) and P(s) are expressed by the following formula:
 
 Cd ( s )= Kp (1 +Kd·s )  (1)
 
 P ( s )=1 /ms 2  (2)
 
then, according to the block diagram illustrated in  FIG. 3 , the disturbance Xm is given by the following formula:
 
 Xm =( Rx−Xi )· Cd ( s )· P ( s )+ Xi   (3)
 
Here, s represents the Laplacian operator, Kp represents a proportional gain, Kd represents a differential coefficient for proportional differential (PD) control, and m represents amass of the reference object  2 .
 
     Since Rx, Cd(s), and P(s) are known values, these values can be stored in advance in the memory section  7 . In other words, the vibration can be estimated based on the measured position Xi. Further, in order to obtain the vibration with a higher degree of accuracy, a servo band in controlling the reference object  2  to follow the member  1  and a resolution of the sensor  4  need to be considered. 
     An example of a servo band and a resolution will now be described. If the position of the reference object  2  is controlled at a high servo band, since follow-up of the reference object  2  to the member  1  becomes high, a deviation of the relative position between the member  1  and the reference object  2  becomes extremely small. In order to detect a small deviation, a sensor with a high resolution is necessary. However, most sensors that have a high resolution are likely to detect noise as well and, therefore, not useful. 
     On the other hand, if the position of the reference object  2  is controlled at a low servo band, since the reference object  2  makes a large movement between each measurement timing, the control system needs to have high linearity characteristics. Thus, the reference object  2  is controlled at a low servo band with a Lorentz-type linear motor as a drive unit. The Lorentz-type linear motor has high linearity characteristics. 
     Where a position control system servo band is Wc, an inverse of a differential coefficient for PD control is Wa (=1/Kd), acceleration of vibration as disturbance (second-order differential of Xm) is Ao, and a minimum resolution of a measured value (Xi) is Eo, approximately the following inequality holds true:
 
 Eo&lt;Ao /( Wc·Wa )  (4)
 
Further, from a viewpoint of stability, where Wa=Wc/2,
 
 Eo&lt; 2 *Ao/Wc   2   (5)
 
and
 
 Wc&lt;√ 2 *Ao/Eo   (6)
 
The inequality (6) implies that if the servo band Wc is greater than the right-hand side, since follow-up control is performed at a smaller resolution than the minimum resolution Eo of the measured value, measurement will not be made correctly.
 
     If, for example, a vibration of the floor on which a semiconductor exposure apparatus is placed satisfies the VC-E (floor vibration allowance criterion) adopted in the Semiconductor Equipment and Materials International (SEMI) standard, since the semiconductor exposure apparatus is a precision apparatus, then Ao=0.016 [Gal]. If the resolution of the sensor is not so high, such as Eo=0.1e−6 [m] as described above, according to the aforementioned approximation, Wc&lt;9.01 [Hz]. 
     In other words, if a sensor with a resolution of 100 nm or less is used, then the servo band can be set at 10 Hz or lower. 
     Vibration of the supporting member  103  can be estimated according to the above-described method. Next, referring to  FIG. 1  again, a method for controlling a vibration of the supporting member  103  using the estimation result will be described. 
     The exposure apparatus  100  includes a drive unit  108  configured to drive the supporting member  103  relative to the base  105 . By driving the drive unit  108  based on an output of the vibration estimation unit  107 , the position of the supporting member  103  can be controlled with high precision. 
     Referring to  FIG. 4 , position control for the above-described supporting member  103  will be described. A control system  801  controls the reference object  2  as described in  FIG. 3 , and a control system  802  controls the supporting member  103 . Since Rx, Cd(s), and P(s) are known values as described above, the vibration can be estimated by a computing unit C 1 ( s )  806  as the vibration estimation section  6  based on the measured position Xi and the values Rx, Cd(s), and P(s). The estimated vibration will be hereinafter referred to as {circumflex over (X)}m. 
     The difference between a target position Rm of the supporting member  103  and the estimated vibration {circumflex over (X)}m is input to a position compensator C 2 ( s )  809 . According to this difference, a drive force that is given by the drive unit  108  to the supporting member  103  is determined. Here, the transfer function of the supporting member  103  includes a transfer function  810  that is represented by a mass M of the supporting member  103 , a transfer function  811  represented by a damping coefficient D of the supporting member  103 , and a transfer function  812  represented by a spring modulus K of the supporting member  103 . A position Xm of the supporting member  103  that is driven by the drive unit  108  is added as a vibration to the output of the sensor  4 . 
     Conventionally, it is possible to control a supporting member according to positional information of the supporting member that is obtained by double integrating the acceleration information detected by an accelerometer arranged on the supporting member in a conventional manner. However, the positional information obtained by double integrating the acceleration information is not sufficiently precise. 
     According to the present exemplary embodiment, since a position sensor using an optical unit, such as a laser interferometer, is used, the vibration of the supporting member can be estimated based on highly precise positional information and the supporting member can be controlled accordingly. 
       FIG. 5  illustrates vibration isolation ratios obtained when an acceleration sensor is used and when a configuration according to an exemplary embodiment of the present exemplary embodiment is used. The vertical axis represents vibration isolation ratio in  FIG. 5 . The horizontal axis represents frequency. Damper eigenvalue is 1 Hz. The broken line represents a case where the accelerometer is used. The acceleration of the supporting member is detected, single-integrated, and fed back by velocity. The solid line represents a case where a configuration according to the present exemplary embodiment is used. Feedback by position is performed. As can be seen from the graph illustrated in  FIG. 5 , a characteristic at a low-frequency range in the case of the present exemplary embodiment is improved. 
     According to the present exemplary embodiment, the reference object  2  is supported by the supporting member  103  via the linear motor  3  and the member  1 . The linear motor  3  is capable of reducing measurement error when measuring a relative displacement between the reference object  2  and the member  1  since the reference object  2  and the member  1  are supported by the supporting member  103 , which supports the projection optical system  102 . This is because the supporting member  103 , which supports the projection optical system  102 , is heat-regulated at high precision so as to minimize deformation due to thermal expansion. 
     Second Exemplary Embodiment 
     A second exemplary embodiment of the present invention controls velocity of the reference object  2 . For configurations that are not specially referred to will be regarded similar to those of the first exemplary embodiment. 
       FIG. 6  is a block diagram illustrating velocity control for the reference object  2 . In  FIG. 6 , Rv is a target velocity (e.g., zero) of the reference object  2 , Ci(s)  307  is a transfer function of a proportional differential compensator  307  in the control section  5 , P(s)  308  is a transfer function of the reference object  2  as a controlled object, and Xi is a relative position of the reference object  2  measured by the sensor  4 . The position of the measured position Xi is converted by a first-order differentiator  310  into velocity and fed back to the target velocity Rv by the control section  5 . 
     The measured position Xi contains a disturbance Xm. Since the disturbance Xm is considered to depend greatly on a vibration of the member  1  (the supporting member  103 ) according to the present exemplary embodiment, this disturbance Xm is estimated to be a vibration. 
     Where the transfer functions Ci(s) and P(s) are expressed in the following formula:
 
 Ci ( s )= Kp (1 +Ki/s )  (7)
 
 P ( s )=1 /ms 2  (8)
 
then, according to the block diagram illustrated in  FIG. 6 , the vibration Xm is given by the following formula:
 
 Xm =( Rv−Xi·s )· Ci ( s )· P ( s )  (9)
 
Here, s represents the Laplacian operator, Kp represents a proportional gain, Ki represents a differential coefficient for proportional integral (PI) control, and m represents a mass of the reference object  2 .
 
     Since Rv, Ci(s), and P(s) are known values, these values can be stored in advance in the memory section  7 . In other words, the vibration Xm can be estimated based on the measured position Xi even when the velocity of the reference object  2  is controlled. 
     The servo band in controlling the velocity of the reference object  2  and the resolution of the sensor  4  are similar to those in the first exemplary embodiment. In other words, the velocity of the reference object  2  is controlled at a low servo band with the linear motor  3  having high linearity, e.g., a Lorentz force linear motor. A brief description of the velocity control will now be given. 
     Where velocity control system servo band is Wc 1 , an inverse of a differential coefficient for PI control is Wa2 (=Ki), acceleration of vibration as disturbance (second-order differential of Xm) is Ao, and a minimum resolution of a measured value (Xi) is Eo, approximately the following inequality holds true:
 
 Eo&lt;Ao /( Wc 2· Wa 2)  (10)
 
Further, from a viewpoint of stability, where Wa2=Wc2/2,
 
 Eo&lt; 2 *Ao/Wc 2 2   (11)
 
and
 
 Wc 2&lt;√2 *Ao/Eo   (12)
 
     If, for example, a vibration of the floor on which a semiconductor exposure apparatus is placed satisfies the VC-E (floor vibration allowance criterion) adopted in the Semiconductor Equipment and Materials International (SEMI) standard, since the semiconductor exposure apparatus is a precision apparatus, then Ao=0.016 [Gal]. If the resolution of the sensor is not so high, such as Eo=0.1e−6 [m] as described above, according to the aforementioned approximation, Wc&lt;9.01 [Hz]. 
     In other words, if a sensor with a resolution of 100 nm or less is used, then the servo band can be set at 10 Hz or lower. 
     Since the relative velocity between the reference object  2  and the member  1  is controlled in the present exemplary embodiment, the positions of the reference object  2  and the member  1  may be displaced from the default positions. Thus, if the position of the reference object  2  exceeds a certain threshold value, it is useful that the position of the reference object  2  is reset to the default position. This can be performed during, for example, wafer exchanging. If the position of the reference object  2  is changed during exposure, it may affect exposure precision. 
     The displacement from the default position tends to be larger when the supporting member is moved upward or downward by the air spring (air mount). This is because the supporting member makes a big movement at a low speed by the air spring. 
     Further, even if determination is not made whether the position of the reference object exceeds a certain threshold value, a calibration sequence can be made to return the position of the reference object to the default position at regular intervals. For example, the calibration can be made at the time the supporting member moves upward by the above-described air spring. 
     Third Exemplary Embodiment 
     A third exemplary embodiment of the present invention has a spring element and a damping element arranged between the member  1  and the reference object  2 . 
       FIG. 7  illustrates a vibration estimation unit according to the third exemplary embodiment. For configurations that are not specially referred to can be regarded similar to those of the first exemplary embodiment. 
     In  FIG. 7 , the reference object  2  is supported by the member  1  with a spring element  407  and a damping element  408  inserted therebetween. The spring element  407  supported by the member  1  and supporting the reference object  2  can be, for example, a leaf spring. An oleo damper or an air damper can be used for the damping element  408 . 
       FIG. 8  is a block diagram illustrating position control for the reference object  2  with the above configuration. In  FIG. 8 , Rx is a target position of the reference object  2 , Cd(s)  507  is a transfer function of a proportional differential (PD) compensator  207  in the control section  5 , Pd(s)  508  is a transfer function of the reference object  2 , and Xi is a position of the reference object  2  measured by the sensor  4 . The position of the measured position Xi is fed back to the target position Rx by the control section  5 . 
     Where the transfer functions Cd(s) and Pd(s) are expressed in the following formula:
 
 Cd ( s )= Kp (1 +Kd·s )  (13)
 
 Pd ( s )=1 /ms 2  (14)
 
then, according to the block diagram illustrated in  FIG. 8 , the vibration Xm is given by the following formula:
 
 Xm=Xi+ {( Rx−Xi )· Cd ( s )+ Xi· ( D·s+K )}· Pd ( s )  (15)
 
Here, s represents the Laplacian operator, Kp represents a proportional gain, Kd represents a differential coefficient for proportional differential (PD) control, m represents a mass of the reference object  2 , K represents a spring modulus of the spring element  407 , and D represents a damping coefficient of the damping element  408 .
 
     Since Rx, Cd(s), and Pd(s) are known values, these values can be stored in advance in the memory section  7 . In other words, the vibration Xm can be estimated based on the measured position Xi. 
     Fourth Exemplary Embodiment 
     A fourth exemplary embodiment of the present invention controls a velocity of the reference object  2  with a configuration of the third exemplary embodiment. For configurations that are not specially referred to shall be regarded similar to those of the third exemplary embodiment. 
       FIG. 9  is a block diagram illustrating velocity control for the reference object  2  using a vibration estimation unit including a spring element and a damping element. 
     In  FIG. 9 , Rv is a target velocity of the reference object  2 , Ci(s)  605  is a transfer function of a proportional integral (PI) compensator in the control section  5 , Pi(s)  608  is a transfer function of the reference object  2 , and Xi is a position of the reference object  2  measured by the sensor  4 . The position of the measured position Xi is fed back to the target velocity Rv by the control section  5 . 
     The measured position Xi contains a disturbance Xm. Since the disturbance Xm is considered to depend greatly on a vibration of the member  1  (the supporting member  103 ) according to the present exemplary embodiment, this disturbance Xm is estimated to be a vibration. 
     Where the transfer functions Ci(s) and Pi(s) are expressed in the following formula:
 
 Ci ( s )= Kp (1 +Ki/s )  (16)
 
 Pi ( s )=1 /ms 2  (17)
 
then, according to the block diagram illustrated in  FIG. 9 , the vibration Xm is given by the following formula:
 
 Xm=Xi·s· ( Rv−Xi·s )· Ci ( s )+ Xi·s· ( D·s+K )} Pi ( s )  (18)
 
Here, s represents the Laplacian operator, Kp represents a proportional gain, Ki represents a differential coefficient for PI control, and m represents a mass of the reference object  2 , K represents a spring modulus of the spring element  407 , and D represents a damping coefficient of the damping element  408 .
 
     Since Rv, Ci(s), and Pi(s) are known values, these values can be stored in advance in the memory section  7 . In other words, the vibration Xm can be estimated based on the measured position Xi even when the velocity of the reference object  2  is controlled. 
     As described above, when the reference object  2  is connected via the spring element  407  or the damping element  408 , power used for driving the linear motor  3  can be reduced. 
     Device manufacturing processes using the above-described exposure apparatus will now be described with reference to  FIGS. 10 and 11 .  FIG. 10  is a flowchart illustrating exemplary processes for manufacturing a semiconductor device (e.g., an integrated circuit (IC), an LSI, a liquid crystal display (LCD), and a charge-coupled device (CCD)) using the above-described exposure apparatus. In the present exemplary embodiment, a method for manufacturing a semiconductor chip will be described as an example. 
     Step S 1  is a circuit design process for designing a circuit of a semiconductor device. Step S 2  is a mask making process for fabricating a mask based on a designed circuit pattern. Step S 3  is a wafer manufacturing process for manufacturing a wafer from a silicon or comparable material. Step S 4  is a wafer process, which can be referred to as “preprocess”, for forming an actual circuit on a wafer using the aforementioned exposure apparatus with the above-described prepared mask according to the lithography technique. 
     Step S 5  is an assembling process, which can be referred to as “postprocess”, for forming a semiconductor chip using the wafer manufactured in step S 4 . The postprocess includes an assembly process (e.g., dicing, bonding, etc.) and a packaging process (chip sealing). Step S 6  is an inspection process for inspecting the semiconductor device manufactured in step S 5 . The inspection includes an operation confirmation test and an endurance test. Step S 7  is a shipment process for shipping the semiconductor device completed through the above-described processes. 
     As illustrated in  FIG. 11 , the above-described wafer process in step S 4  includes an oxidation step S 11  for oxidizing a wafer surface, a chemical vapor deposition (CVD) step S 12  for forming an insulating film on the wafer surface, and an electrode formation step S 13  for forming electrodes on the wafer by vaporization. Furthermore, the wafer process in step S 4  includes an ion implantation step S 14  for implanting ions into the wafer, and a resist processing step S 15  for coating the wafer with a photosensitive material. 
     Furthermore, the wafer process in step S 4  includes an exposure step S 16  for exposing the wafer subjected to the resist processing step to light using the above-described exposure apparatus with a mask having a circuit pattern, a developing step S 17  for developing the wafer exposed in the exposure step S 16 , an etching step S 18  for cutting a portion other than a resist image developed in the developing step S 17 , and a resist stripping step S 19  for removing an unnecessary resist remaining after the etching step S 18 . The processing repeating the above-described steps can form multiple circuit patterns on a wafer. 
     According to the above-described exemplary embodiments, an exposure apparatus that is capable of reducing vibration with a high degree of accuracy can be realized. 
     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. 2006-354430 filed Dec. 28, 2006, which is hereby incorporated by reference herein in its entirety.