JP2006060152A - Optical characteristic measuring apparatus, stage apparatus and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical characteristic measuring apparatus for preventing the position controllability of a table from being reduced and suppressing the influence of heat on peripheral members. <P>SOLUTION: The optical characteristic measuring apparatus 28 is provided with a first part 28A mounted on a table WTB, and including an objective optical system 94 on which light through an optical system to be checked is made incident; and a second part mounted on a mobile body 30 connected to the table WTB so as to be relatively moved, and including detector 95 for detecting light through the objective optical system. Consequently, the weight of the table on which the first part 28A is mounted is not increased and the table can be driven according to the comparatively heavy second part. Since the second part can be mounted on the second mobile object separately from the optical system to be checked, a state that heating of the second part may cause atmospheric air fluctuation around the optical system to be checked can be suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical characteristic measuring apparatus, a stage apparatus, and an exposure apparatus. More specifically, the present invention relates to an optical characteristic measuring apparatus that measures optical characteristics of a test optical system such as a projection optical system, a stage apparatus including the optical characteristic measuring apparatus, and The present invention relates to an exposure apparatus including the stage apparatus.

  Conventionally, in a lithography process for manufacturing semiconductor elements, liquid crystal display elements, etc., a step-and-repeat type reduction projection exposure apparatus (so-called stepper) and a step-and-scan type scanning projection exposure apparatus (so-called scanning scanning exposure apparatus). An exposure apparatus such as a stepper (also called a scanner) is used.

  In recent years, in these exposure apparatuses, the circuit pattern has become finer in response to the higher integration of semiconductor elements and the improvement in resolving power is inevitably required. Therefore, it has been required to suppress the aberration to the limit. In order to meet such demands, conventionally, in the adjustment process of the projection optical system alone, the projection optical system is a large-scale measuring instrument for measuring the wavefront aberration of the projection optical system using a dedicated wavefront measuring instrument (for example, an interferometer or the like). It was mounted on a measuring instrument), its wavefront aberration was measured, and the aberration was strictly adjusted based on the measurement result.

  However, along with further higher integration of semiconductor elements, the environmental changes between the state of the projection optical system alone and the state of being incorporated in the exposure apparatus main body, and the unexpected accident when incorporating it in the exposure apparatus main body have been recently developed. Or, from the viewpoint of quality assurance by measuring immediately before shipment, after the projection optical system is incorporated in the exposure apparatus body, the wavefront aberration of the projection optical system is incorporated in the exposure apparatus body (so-called on-body). The need to measure has arisen.

  As a wavefront measuring device that measures the wavefront aberration of an on-body projection optical system, it is a portable type Shack-Hartmann that is detachably attached to a substrate stage (wafer stage) on which a substrate (wafer) is placed. A wavefront aberration measuring instrument of the type is known (for example, see Patent Document 1).

  However, in the case of the portable type wavefront aberration measuring instrument described above, the step of attaching the wavefront aberration measuring instrument to the wafer stage and the step of removing the wavefront aberration measuring instrument from the wafer stage after the measurement of the wavefront aberration are indispensable. There is an inconvenience that the downtime of the apparatus for the measurement is inevitably long. In addition, the reproducibility of the position at the time of mounting is not necessarily sufficient.

  For these reasons, a wavefront aberration measuring device of the type that is permanently installed on the wafer stage has recently been attracting attention. However, when, for example, a Shack-Hartmann type wavefront aberration measuring apparatus is permanently installed on the wafer stage, the presence of the CCD constituting the wavefront aberration measuring apparatus makes the components of the wafer stage on which the wavefront aberration measuring apparatus is provided heavy. When measuring the wavefront aberration, the wavefront aberration measuring device needs to be provided on the wafer table portion on which the wafer is placed because it is necessary to position the sign plate of the wavefront aberration measuring device on the best imaging plane of the projection optical system.

  However, particularly in a scanning exposure apparatus such as a scanning stepper, the table portion needs to match the surface of the wafer W in the illumination light irradiation region within the focal depth range of the projection optical system during scanning exposure. It is necessary to drive at high speed. Therefore, it is not desirable to increase the weight of the wafer table portion, and it is rather desirable to reduce the weight in order to improve controllability.

  Further, when a wavefront aberration measuring device is permanently installed on the wafer stage, there is a problem that the heat generated by the CCD itself or the drive circuit of the CCD, such as a charge transfer control circuit, has an influence on peripheral devices. An optical position measuring device such as a laser interferometer that measures the position of the wafer stage and a focus sensor that detects the position of the wafer surface in the optical axis direction is provided near the wafer stage where the wavefront aberration measuring device is permanently installed. However, due to the heat generated by the above-described CCD or the like, so-called air fluctuations (air temperature fluctuations) may occur in the optical path space of the detection beams of those position measurement devices, and the measurement accuracy of the position measurement devices may be reduced. was there. In addition, since a laser interferometer, a focus sensor, and the like are usually used for position measurement of a wavefront aberration measuring apparatus, there is a possibility that the measurement accuracy of the wavefront aberration may be lowered as a result.

WO99 / 60361 pamphlet

  The inventors have conducted intensive research to realize a wavefront aberration measuring apparatus that can be permanently installed on the wafer stage of the exposure apparatus and that can avoid the adverse effects caused by the weight of the wafer table and the heat generation of the light receiving element described above. However, perhaps due to the decrease in measurement accuracy, he came up with a new idea of “dividing the wavefront aberration measurement device into multiple parts”, which had never been studied. As an example, the Shack-Hartmann wavefront aberration measuring device is divided into a first portion including an objective optical system and a second portion including a detection device such as a CCD, and each portion is divided into a wafer table of an exposure apparatus. As a result of repeatedly performing various experiments and simulations under the assumption that they are attached to the wafer stage and the wafer stage, even if the wavefront aberration measuring device is divided into two as described above, the wavefront aberration measuring device is sufficient for practical use. It came to the conclusion that wavefront aberration can be measured with high accuracy. As a result, it was also confirmed that there was no problem in accuracy even if the microlens array was included in either the first part or the second part. In the case of an optical characteristic measuring apparatus permanently installed on the wafer stage, it is expected that the same problem can be improved by dividing the optical system and the light receiving element as in the case of the Shack-Hartmann wavefront aberration measuring apparatus. The

  The present invention has been made under the circumstances described above. From the first viewpoint, the present invention is an optical characteristic measuring apparatus for measuring the optical characteristics of a test optical system (PL), and includes a first moving body ( A first portion (28A) provided in the WTB) and including an objective optical system (94) on which light through the test optical system enters; a second portion connected to the first moving body so as to be relatively movable A second portion (28B) provided on the movable body (31) and physically separated from the first portion and including at least a detection device (95) for detecting light via the objective optical system; Is an optical characteristic measuring apparatus.

  According to this, the 1st part containing the objective optical system in which the light which passes through a to-be-tested optical system injects is provided in the 1st moving body, and the detection apparatus (for example, the light which passes through the said objective optical system (for example) And a second portion physically separated from the first portion is provided in a second moving body connected to the first moving body so as to be relatively movable. For this reason, the first moving body provided with the first portion is not increased in weight, and the first moving body is compared with the second moving body provided with the relatively heavy second portion. Can be driven. Accordingly, the optical characteristic measuring device including the first part and the second part can be permanently installed in the first and second moving bodies, while the first moving body is made of a lightweight member such as an objective optical system. Since only the first portion is provided, weight is not increased. Further, since the second part can be provided on the second moving body away from the test optical system, it is possible to suppress the heat generation of the second part from causing air fluctuations in the atmosphere around the test optical system. can do.

  From a second viewpoint, the present invention includes a stage (31) that moves in a two-dimensional plane, and a table (WTB) that is movable on the stage in at least a direction orthogonal to the two-dimensional plane. A moving body (WST); a drive system (27) for driving the moving body; the first portion (28A) provided on the table, and the second portion (28B) provided on the stage. And an optical characteristic measuring device (28).

  According to this, a movable body including a stage that moves in a two-dimensional plane, a table that is movable on the stage in a direction orthogonal to the two-dimensional plane, and a drive system that drives the movable body And. And it was physically separated into the 1st part containing the objective optical system in which the light which passes through a to-be-tested optical system injects, and the 2nd part containing at least the detection apparatus which detects the light through the said objective optical system The first part of the optical property measuring apparatus of the present invention is provided on the table, and the second part is provided on the stage. That is, the relatively light first part is provided in a table that requires high responsiveness during driving and high position controllability, and the second part including at least a relatively heavy detection device is compared to the table. It is provided on a stage that does not require high responsiveness or high position controllability during driving. Therefore, the optical characteristic measuring apparatus can be permanently installed on the moving body, and the responsiveness and position controllability required for each stage and table constituting the moving body can be sufficiently satisfied. Further, since the second portion can be provided on the stage away from the test optical system, it is possible to suppress the heat generation of the second portion from causing air fluctuations in the atmosphere around the test optical system. .

  In this case, it is possible to further include a cooling mechanism that is provided on the stage and cools at least a part of the stage including the second portion. In such a case, since at least a part of the stage including the second part can be cooled by the cooling mechanism, the heat generated by the detection device included in the second part is caused by the surrounding members and atmosphere of the second part. Etc. can be suppressed.

  From a third viewpoint, the present invention is an exposure apparatus that exposes an object (W) with exposure light (IL) via a projection optical system (PL) and transfers a predetermined pattern onto the object, An exposure apparatus comprising the stage apparatus according to the present invention, wherein the object is placed on the table, and the projection optical system is the optical system to be measured of the optical characteristic measurement apparatus.

  According to this, since the object is placed on the table and the projection optical system is provided with the stage device that uses the optical characteristic measuring device as the test optical system, the optical characteristic measuring device can control the optical characteristics of the projection optical system. Measurement can be performed with sufficient accuracy, and the projection optical system can be adjusted based on the measurement result. Then, by performing the above-described exposure using the adjusted projection optical system, the pattern can be accurately transferred onto the object. In addition, since the table on which the object is placed has high responsiveness and high position controllability during driving, the object surface in the irradiation area of the exposure light during scanning exposure matches the depth of focus range of the projection optical system. It becomes possible to make it. Also in this respect, it is possible to realize highly accurate exposure.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to an embodiment of the present invention. The exposure apparatus 100 is a step-and-scan projection exposure apparatus (also called a scanning stepper (scanner)).

  The exposure apparatus 100 includes a light source and an illumination optical system. The illumination system 10 illuminates the reticle R with illumination light IL as exposure light, a reticle stage RST that holds the reticle R as a mask, a projection unit PU, and an object as an object. A wafer stage WST as a moving body on which the wafer W is placed, a body BD on which the reticle stage RST and the projection unit PU are mounted, a control system for these, and the like are provided.

  The illumination system 10 includes an illumination uniformizing optical system including a light source, an optical integrator, etc., as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-313250 (corresponding to US Patent Application Publication No. 2003/0025890). It includes a splitter, a relay lens, a variable ND filter, a reticle blind, etc. (all not shown). In the illumination system 10, a slit-shaped illumination area that is defined by a reticle blind and extends elongated in the X-axis direction on the reticle R is illuminated with substantially uniform illuminance by the illumination light IL. Here, as the illumination light IL, for example, ArF excimer laser light (wavelength 193 nm) is used. As the optical integrator, a fly-eye lens, a rod integrator (an internal reflection type integrator), a diffractive optical element, or the like can be used.

  The reticle stage RST is levitated and supported on a reticle base 36 constituting a top plate of a second column 34, which will be described later, with a clearance of about several μm, for example, by an air bearing (not shown) provided on the bottom surface thereof. Yes. On reticle stage RST, reticle R is fixed by, for example, vacuum suction (or electrostatic suction). Here, the reticle stage RST is two-dimensionally (X-axis direction, Y-axis) in a horizontal plane (XY plane) by a reticle stage drive unit 12 (not shown in FIG. 1, see FIG. 6) including a linear motor or the like. Direction and a rotational direction (θz direction) around the Z axis perpendicular to the XY plane, and on the reticle base 36 in a predetermined scanning direction (here, the Y axis direction which is a direction perpendicular to the plane of FIG. 1) It is possible to drive at the scanning speed specified in the above.

  The position of the reticle stage RST in the stage movement plane is determined by a projection unit by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 16 that irradiates a measuring mirror onto a movable mirror 15 fixed on the reticle stage RST. With a fixed mirror (reference mirror) 14 fixed to the side surface of the PU barrel 40 as a reference, it is always detected with a resolution of about 0.5 to 1 nm, for example. Here, actually, the movable mirror is provided with a Y movable mirror having a reflecting surface orthogonal to the Y-axis direction and an X moving mirror having a reflecting surface orthogonal to the X-axis direction, and corresponds to these movable mirrors. The reticle interferometer is also provided with a reticle Y interferometer and a reticle X interferometer, and further, corresponding to these, a fixed mirror for measuring the X-direction position and a fixed mirror for measuring the Y-direction position are provided. However, in FIG. 1, these are typically shown as a movable mirror 15, a reticle interferometer 16, and a fixed mirror 14. For example, the end surface of the reticle stage RST may be mirror-finished to form a reflecting surface (corresponding to the reflecting surface of the movable mirror 15). Further, at least one corner cube type mirror (for example, a retroreflector) is used instead of the reflecting surface extending in the X-axis direction used for detecting the position of the reticle stage RST in the scanning direction (Y-axis direction in the present embodiment). Also good. Here, one of the reticle Y interferometer and the reticle X interferometer, for example, the reticle Y interferometer is a two-axis interferometer having two measurement axes, and the reticle stage RST is based on the measurement value of the reticle Y interferometer. In addition to the Y position, rotation in the θz direction can also be measured.

  The measurement value of reticle interferometer 16 is sent to main controller 50 shown in FIG. 6, and main controller 50 uses reticle stage drive unit 12 and reticle stage RST based on the measurement value of reticle interferometer 16. Is controlled.

  The projection unit PU is held on the lens barrel surface plate 38 constituting the body BD via a flange FLG below the reticle stage RST in FIG.

  The body BD includes a first column 32 installed on a frame caster FC installed on the floor F of the clean room, and a second column 34 fixed on the first column 32.

  The frame caster FC includes a base plate BS and a plurality of, for example, three (or four) leg portions 39 provided on the base plate BS (however, the leg portions on the back side in FIG. 1 are not shown). A plurality of, for example, three first vibration isolation mechanisms 56 fixed to the upper ends of the leg portions 39 are provided. Each first vibration isolation mechanism 56 can finely drive the air mount 60 and the lens barrel surface plate 38, which are connected in series to the upper part of the leg portion 39 and can adjust the internal pressure, in the gravitational direction (Z-axis direction) with high response. And a voice coil motor 62 (see FIG. 6). Each component of the first vibration isolation mechanism 56 is controlled by the main controller 50 (see FIG. 6).

  The first column 32 includes the lens barrel surface plate (main frame) 38 supported substantially horizontally by the leg portion 39 and the first vibration isolation mechanism 56.

  On the upper surface of the lens barrel surface plate 38, one end (lower end) of a plurality of, for example, three legs 41 (note that the legs on the back side of the drawing in FIG. 1 are not shown) is fixed at a position surrounding the projection unit PU. Has been. The other end (upper end) surface of each leg 41 is on substantially the same horizontal plane, and the lower surface of the reticle base 36 is fixed to the upper end surface of each leg 41. In this way, the reticle base 36 is horizontally supported by the plurality of legs 41. That is, the second column 34 is configured by the reticle base 36 and the three legs 41 that support the reticle base 36. The reticle base 36 is formed with an opening 36a serving as a passage for the illumination light IL at the center thereof.

  The projection unit PU is cylindrical and has a lens barrel 40 provided with a flange FLG in the vicinity of the lower end portion of the outer peripheral portion thereof, and a projection optical system as a test optical system comprising a plurality of optical elements held by the lens barrel 40. System PL. As the projection optical system PL, for example, a refractive optical system including a plurality of lenses (lens elements) having a common optical axis AX in the Z-axis direction is used. This projection optical system PL is, for example, both-side telecentric and has a predetermined projection magnification (for example, 1/4 or 1/5). For this reason, when the reticle R is illuminated by the illumination light IL from the illumination system, the reduced image of the circuit pattern of the reticle R in the illumination area is projected via the projection optical system PL by the illumination light IL that has passed through the reticle R. (A reduced image of a part of the circuit pattern) is formed on the wafer W having a surface coated with a resist (photosensitive agent).

  In the present embodiment, among the plurality of lens elements, a plurality of lens elements including the lens element closest to the reticle R (hereinafter referred to as “movable lens”) can be driven independently. In the present embodiment, the image formation characteristic correction controller 76 (see FIG. 6) controls the applied voltage of a drive element (not shown) that drives the movable lens based on a command from the main control device 50, thereby causing projection. The optical characteristics (for example, distortion (including magnification), astigmatism, coma aberration, spherical aberration, curvature of field (focus)) of the optical system PL are adjusted.

  Wafer stage WST is levitated and supported on the upper surface of stage base 71 disposed horizontally below projection unit PU in a non-contact manner via an air bearing or the like provided on the bottom surface thereof. On wafer stage WST, wafer W is held by vacuum suction (or electrostatic suction) via a wafer holder (not shown).

  The stage base 71 includes a plurality of (for example, three) support members 73 provided at a plurality of locations (for example, three locations) on the base plate BS, and a plurality of (for example, three) fixed to the upper surface of each of the support members 73. The second vibration isolation mechanism 66 is supported substantially horizontally. As shown in FIG. 6, each second vibration isolation mechanism 66 includes an air mount 68 and a voice coil motor 72 in the same manner as the first vibration isolation mechanism 56 described above. The motor 72 is controlled by the main controller 50.

  The + Z side surface (upper surface) of the stage base 71 is processed so as to have a very high flatness, and is used as a movement reference surface (guide surface) of the wafer stage WST. In exposure apparatus 100 of the present embodiment, the upper surface of stage base 71 (the guide surface of wafer stage WST) is inclined with respect to a plane (XY plane) orthogonal to optical axis AX of projection optical system PL and in the direction of optical axis AX ( A measurement mechanism for measuring position information regarding the Z-axis direction) is provided. As shown in FIG. 1, the measuring mechanism includes three Z interferometers 102a to 102c (in FIG. 1, Z on the back side of the drawing) provided at three positions not in the same straight line of the lens barrel surface plate 38, respectively. The interferometer 102c is configured by an unillustrated reference (see FIG. 6). Each of the Z interferometers 102 a to 102 c detects position information regarding the Z-axis direction at each measurement point on the upper surface of the stage base 71 with reference to the lens barrel surface plate 38. Outputs of the Z interferometers 102a to 102c are supplied to the main controller 50 shown in FIG. Main controller 50 calculates the Z position of the upper surface of stage base 71 based on the average value of the measured values of Z interferometers 102a to 102c, and determines the position of stage base 71 based on the measured values of Z interferometers 102a to 102c. The inclination (θx rotation, θy rotation) of the upper surface with respect to the XY plane is calculated.

  Wafer stage WST is arranged below projection unit PU in FIG. 1, is driven by wafer stage drive unit 27 (see FIG. 6) described later, and moves in the XY plane along the guide surface.

More specifically, the wafer stage WST includes a stage 31 as a second moving body and a Z / tilt drive mechanism VZ ₁ to VZ ₁ on the stage 31 as shown in the perspective view of FIG. And a table WTB as a first moving body mounted via VZ ₃ (not shown in FIG. 2, see FIG. 5). The Z / tilt driving mechanisms VZ _{1 to} VZ ₃ are actually configured to include three actuators (for example, a voice coil motor or an EI core) that support the table WTB on the stage 31 at three points, and the table WTB. Are driven minutely in the three-degree-of-freedom directions of the Z-axis direction, θx direction (rotation direction around the X axis), and θy direction (rotation direction around the Y axis).

  The stage 31 includes a top plate 30 and a Y mover 132Y fixed to the lower surface of the top plate 30. A plurality of air bearings (not shown) are provided on the lower surface of the stage 31 (the lower surface of the Y movable element 132Y), and the wafer stage WST passes above these guide surfaces via a clearance of about several μm via these air bearings. It is supported by levitating without contact.

  As shown in FIG. 2, the Y mover 132 </ b> Y is mutually connected to a mover yoke (magnet plate) 138 having a rectangular frame shape and extending in the Y-axis direction, and an upper and lower opposing surface on the inner surface side of the mover yoke 138. A plurality of field magnets 137 made of N-pole permanent magnets and S-pole permanent magnets that are opposed to each other and arranged alternately at a predetermined interval along the Y-axis direction are provided. In this case, the polarities of the field magnets adjacent to each other are opposite to each other, and the polarities of the field magnets facing each other are also opposite to each other. For this reason, an alternating magnetic field is formed in the inner space of the mover yoke 138 along the Y-axis direction.

  A Y-axis stator 134Y whose longitudinal direction is the Y-axis direction is inserted into the inner space of the mover yoke 138 of the Y mover 132Y. Here, the Y-axis stator 134Y is configured by an armature unit having a plurality of armature coils arranged along the Y-axis direction.

  In this case, the Y mover 132Y and the Y axis stator 134Y constitute a moving magnet type electromagnetic force drive type Y axis linear motor 136Y that drives the wafer stage WST in the scanning direction (Y axis direction) ( (See FIG. 3).

As shown in FIG. 3, X movers 132X ₁ and 132X ₂ are fixed to one end (−Y side) and the other side (+ Y side) in the longitudinal direction of the Y-axis stator 134Y. Has been. As shown in FIG. 2, the X mover 132X ₂ on the + Y side has a T-shaped YZ cross section, and an armature coil (not shown) is arranged in the X axis direction inside (or outside). It is arranged at a predetermined interval along. That is, the X mover 132X ₂ is configured by an armature unit.

The −Y side X mover 132X ₁ is configured in the same manner as the X mover 132X _{2 although} it is bilaterally symmetric.

As shown in the plan view of FIG. 3, _one X mover 132 </ b> X ₁ has a moving coil electromagnetic force together with an X-axis stator 134 </ b> X ₁ disposed on the −Y side of the stage base 71 and extending in the X-axis direction. constitute the X-axis linear motor 136X ₁ consisting of a linear motor of the drive system. In other words, the X-axis stator 134X ₁ has a Y-shaped U-shaped cross section, and the two support members 164 fixed on the floor surface F are used to move the vicinity of one end and the other end in the longitudinal direction. Each is supported. The X-axis stator 134X ₁ has a plurality of field magnets arranged at predetermined intervals along the X-axis direction on the inner upper and lower opposing surfaces in the same manner as the Y-movable element 132Y described above. An alternating magnetic field is formed along the direction. An X mover 132X ₁ is inserted in the alternating magnetic field.

The other X mover 132X ₂ is configured symmetrically with the X axis stator 134X _1, and together with the X axis stator 134X ₂ supported on the floor surface F by two support members 166, is a moving coil type. An X-axis linear motor 136X ₂ composed of an electromagnetic force drive type linear motor is constructed.

In the present embodiment, wafer stage WST is driven along the X-axis direction together with Y-axis linear motor 136Y by X-axis linear motors 136X ₁ and 136X ₂ . In addition, wafer stage WST can be rotated in the θz direction by slightly varying the X-axis electromagnetic force (driving force) generated by X-axis linear motors 136X ₁ and 136X ₂ , respectively.

That is, in the present embodiment, wafer stage WST is freely driven in the XY _two- dimensional plane by Y-axis linear motor 136Y that drives wafer stage WST in the Y-axis direction and a pair of X-axis linear motors 136X ₁ and 136X _2. An XY drive unit is configured. The stage 31 is driven with a predetermined stroke in the X-axis and Y-axis directions by the XY drive unit and the Z / tilt drive mechanisms VZ _{1 to} VZ ₃ described above, and the table WTB is driven in the Z-axis direction, θx direction, θy. A wafer stage drive unit 27 (see FIG. 6) is configured as a drive system that finely drives in the direction and θz direction. Each component of the wafer stage drive unit 27 is controlled by the main controller 50 (see FIG. 6).

  Wafer W is sucked and held on the upper surface of table WTB by vacuum suction (or electrostatic suction) or the like via a wafer holder (not shown).

  Returning to FIG. 1, the position information of the wafer stage WST in the XY plane is based on a wafer laser interferometer (hereinafter, “ 18) (referred to as “wafer interferometer”) 18 is always detected with a resolution of about 0.5 to 1 nm, for example, with reference to the reflecting surface of the fixed mirror 29 fixed to the side surface of the barrel 40 of the projection unit PU. The wafer interferometer 18 is fixed to the lower surface of the lens barrel surface plate 38 in a suspended and supported state.

  Here, on wafer stage WST (more precisely, table WTB), actually, as shown in FIG. 2 (and FIG. 3), Y having a reflecting surface orthogonal to the Y-axis direction that is the scanning direction. A movable mirror 17Y and an X movable mirror 17X having a reflecting surface orthogonal to the X-axis direction, which is a non-scanning direction, are provided, and an X laser interferometer 18X and a Y laser interferometer 18Y are provided correspondingly (see FIG. 3), and fixed mirrors are also provided for X-axis direction position measurement and Y-axis direction position measurement, respectively, but in FIG. 1, these are representatively movable mirror 17, wafer interferometer 18, and fixed mirror. Illustrated as mirror 29.

  For example, the end surface of the table WTB may be mirror-finished to form a reflecting surface (corresponding to the reflecting surfaces of the movable mirrors 17X and 17Y). The X laser interferometer 18X and the Y laser interferometer 18Y are multi-axis interferometers having a plurality of measurement axes. In addition to the X and Y positions of the table WTB, rotation (yawing (rotation in the θz direction)), pitching (θx Direction rotation) and rolling (rotation in the θy direction)) can also be measured. Therefore, in the following description, it is assumed that the wafer interferometer 18 measures position information of the table WTB in the X, Y, θz, θy, and θx directions in five degrees of freedom.

  The position information (or speed information) of the table WTB is sent to the main controller 50 in FIG. 6, and the main controller 50 determines the wafer stage drive unit 27 (more precisely, based on the position information (or speed information)). The position of wafer stage WST in the XY plane is controlled via the above-described XY drive unit). Here, the wafer stage WST is controlled on the basis of the position information of the table WTB. From the wafer interferometer 18, the position information of the table WTB in the X, Y, θz, θy, and θx directions in five degrees of freedom. Is supplied to the main controller 50, but the position information in the θy and θx directions other than the X, Y, and θz directions is a position measurement error (a kind of position error in the X and Y axis directions caused by the inclination of the table WTB). This is because the position of the wafer stage WST in the XY plane is corrected based on the calculation result. That is, the position information in the θy and θx directions is not directly used for adjusting the tilt of the table WTB.

  The corner portions of the table WTB and the + X side end and the −Y side end of the top plate 30 are, as shown in FIG. 2, a first portion 28A and a second portion 28B that are physically separated from each other. A wavefront measuring device 28 is attached as an optical characteristic measuring device having The first portion 28A constituting the wavefront measuring instrument 28 is provided on the table WTB side, and the second portion 28B is provided on the top plate 30.

  As shown in FIG. 4, the first portion 28A constituting the wavefront measuring instrument 28 is fixed to a notch formed at the corner portion of the + X side end portion and the −Y side end portion of the table WTB. A first housing 86 that is integrated with the WTB and forms an apparently rectangular plate, and an objective optical system 94 that is disposed inside the first housing 86 and is held via a holding member (not shown). Yes.

  The second portion 28 </ b> B is fixed to a notch formed at the corner portion of the + X side end portion and the −Y side end portion of the top plate 30, and constitutes a substantially rectangular plate integrally with the top plate 30. Second housing 87, microlens array MLA as a wavefront splitting optical element provided at a predetermined position inside second housing 87, and detection device provided below microlens array MLA (on the −Z side) 95.

  The first housing 86 is formed of a hollow box-shaped member having circular openings 86a and 86b formed on the upper wall (+ Z side wall) and the bottom wall (−Z side wall), respectively. A sign plate 88 is provided at the upper end of the first housing 86 so as to close the opening 86a. The sign plate 88 uses a glass substrate as a base material, and the surface thereof is approximately the same height as the surface of the wafer W fixed to the wafer holder. A light shielding film having a circular opening 88a at the center is formed by vapor deposition of a metal such as chrome on the upper surface of the marking plate 88, and measurement of the wavefront aberration of the projection optical system PL as the test optical system is performed by the light shielding film. At this time, unnecessary light from the surroundings is blocked from entering the objective optical system 94 inside the first housing 86. Three or more sets of two-dimensional position detection marks are formed around the opening 88a on the surface of the marking plate 88. The surface of the marking plate 88 has a pinhole pattern for measuring self-aberration having a predetermined diameter, for example, about 10 μm, which generates a spherical wave as an almost ideal point light source when light is irradiated from above. Is formed.

  The second casing 87 is made of a hollow box-shaped member having a circular opening 87a formed in the upper wall (+ Z side wall). The microlens array MLA has a plurality of small lens elements arranged in an array in a plane orthogonal to the optical axis AX as shown in FIG. Here, for example, a lens element LS shown in FIG. 10A is used as each convex lens element constituting the microlens array MLA.

  The detection device 95 includes a light receiving element 92 composed of a two-dimensional CCD and the like, and an electric circuit 90 for driving the light receiving element 92, and is fixed to the inner bottom surface of the second casing 87. The light receiving element 92 has a light receiving surface having an area sufficient to receive all of the light beams incident on the objective optical system 94 and emitted from the microlens array MLA. The electric circuit 90 is a circuit that must be disposed in the vicinity of the light receiving element 92 due to its function, for example, an electric circuit such as a charge transfer control circuit. The electric circuit that can be physically separated from the light receiving element 92 is disposed at a position away from wafer stage WST, and is connected to electric circuit 90 by a flat cable (not shown). In addition, the measurement data by the detection apparatus 95 is output to the main control apparatus 50 (refer FIG. 6).

  By the way, in the present embodiment, since the wafer stage WST is driven using a linear motor, a voice coil motor, or the like as described above, the heat generated by these motors affects the surrounding atmosphere and consequently the exposure accuracy. In order to suppress this as much as possible, the top plate 30 is provided with a cooling mechanism 150 (see FIG. 5).

  FIG. 5 is a plan view showing a state where table WTB is detached from wafer stage WST in order to show the configuration of cooling mechanism 150. As shown in FIG. 5, on the top surface of the top plate 30 of the stage 31, there is provided a first pipe 177 bent into a predetermined shape as shown. One end of a supply pipe 175 is connected to one end (−Y side end) of the first pipe 177 via a connector 176. A fluid supply device 131a (see FIG. 6) is connected to the other end of the supply pipe 175. In addition, one end of the second pipe 179 is connected to the other end (+ Y side end) of the first pipe 177 via a connector 178. The second pipe 179 is laid over the entire bottom surface of the top plate 30. A part of the second pipe 178 is also laid on the bottom surface of the second portion 28 </ b> B of the wavefront measuring instrument 28. One end of a discharge pipe 182 is connected to the other end of the second pipe 179 via a connector 181, and the other end side of the discharge pipe 182 is connected to a fluid recovery device 131b (see FIG. 6).

  A temperature-controlled refrigerant such as water or hydrofluoroether (HFE) is supplied from the fluid supply device 131 a to the first pipe 177 through the supply pipe 175 and the connector 176. Then, the refrigerant is recovered by the fluid recovery device 131 b via the connector 181 and the discharge pipe 182 via the second pipe 179 and the connector 178.

  In the present embodiment, the piping 175, 177, 179, 182; the connectors 176, 178, 181; the fluid supply device 131a; and the fluid recovery device 131b constitute a cooling mechanism 150.

The cooling mechanism configured in this manner cools the top plate 30 constituting the stage 31 and eventually the actuators and Y linear motors constituting the Z / tilt drive mechanisms VZ _{1 to} VZ ₃ , and the wavefront measuring instrument 28. The detection device 95 inside the second portion 28B is cooled.

  In the present embodiment, a wafer stage WST including a stage 31 and a table WTB movable on the stage 31 in the Z-axis, θx, and θy directions, and a wafer stage driving unit 27 that drives the wafer stage WST, A stage apparatus is configured including the wavefront measuring instrument 28.

  As shown in FIG. 1, the exposure apparatus 100 of the present embodiment includes an irradiation system 60a fixed in a suspended state below the lens barrel surface plate 38 holding the projection unit PU, and a light receiving system 60b. For example, an oblique incidence type multi-point focal position detection system having the same structure as that disclosed in Japanese Patent Laid-Open No. 6-283403 (corresponding to US Pat. No. 5,448,332) is provided. . In this case, the irradiation system 60a and the light receiving system 60b and the projection unit PU are attached to the same member (lens barrel surface plate 38), and the positional relationship between them is maintained constant.

  The light source in the irradiation system 60a of this multipoint focal position detection system is controlled to be turned on / off by the main controller 50, and an output signal (defocus signal (defocus signal)) from the light receiving system 60b is sent to the main controller. 50 (see FIG. 6). Main controller 50 calculates the Z position, θx direction rotation, and θy direction rotation of the surface of wafer W based on a defocus signal (defocus signal), for example, an S curve signal, during scanning exposure, and the calculation result. Based on the above, the movement of the table WTB in the Z-axis direction via the wafer stage drive unit 27 (more precisely, the Z / tilt drive mechanism) and the tilt in the two-dimensional direction (that is, rotation in the θx and θy directions) Is controlled so that the imaging plane of the projection optical system PL substantially matches the surface of the wafer W within the irradiation area of the illumination light IL (the irradiation area of the illumination light IL conjugate with the above-described illumination area). Perform focus (autofocus) and auto leveling.

  Although not shown, in the exposure apparatus 100 of the present embodiment, positions of reference marks (not shown) on the table WTB and alignment marks on the wafer in the X and Y two-dimensional directions are near the projection unit PU. An off-axis alignment system for detecting information is provided. As this alignment system, for example, the target mark is irradiated with a broadband detection light beam that does not sensitize the resist on the wafer, and the target mark image formed on the light receiving surface by the reflected light from the target mark and an index (not shown) An image processing type FIA (Field Image Alignment) type alignment sensor that captures the image of the image using an image sensor (CCD) or the like and outputs the imaged signals is used. In the present embodiment, this alignment system is also used for detecting the two-dimensional position detection mark on the above-described sign plate 88.

  FIG. 6 is a simplified block diagram showing the main configuration of the control system in the exposure apparatus 100. This control system is configured around the main controller 50. The main controller 50 includes a so-called microcomputer (or workstation) including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. To control.

  Next, the on-body wavefront aberration measurement operation of the projection optical system PL performed in the exposure apparatus 100 of the present embodiment configured as described above will be described in accordance with the flowchart of FIG. This will be described with reference to the drawings.

As a premise, the positional relationship between the opening 88a of the sign plate 88 of the wavefront measuring instrument 28 and the pinhole pattern for self aberration measurement (not shown) and the wafer stage WST (table WTB) is determined by the two-dimensional position mark on the sign plate 88. It is assumed that it is accurately obtained by observing with an alignment system. That is, the main controller 50 can accurately detect the XY positions of the opening 88a of the marking plate 88 and the pinhole pattern for self aberration measurement based on the position information (velocity information) output from the wafer interferometer 18, In addition, by driving and controlling wafer stage WST via wafer stage drive unit 27, it is assumed that opening 88a of marking plate 88 and the pinhole pattern for self-aberration measurement can be accurately positioned at a desired XY position. Further, the Z tilt drive mechanisms VZ _{1 to} VZ ₃ are controlled so that the stage 31 and the table WTB have a predetermined positional relationship.

First, in step 110, based on an instruction from the main controller 50, a reticle loader (not shown) loads a measurement reticle RT for wavefront aberration measurement shown in FIG. 8 onto the reticle stage RST. As shown in FIG. 8, the measurement reticle RT has a plurality of (9 in FIG. 8) pinhole patterns PH _{1 to} PH _N having a predetermined diameter, for example, 26 μm, in the X-axis direction and the Y-axis direction. It is formed in a matrix arrangement along. Note that the pinhole patterns PH _{1 to} PH _N are formed in a region having the size of the slit-like illumination region indicated by the dotted line in FIG. 8, and in the vicinity of this region, a plan view (viewed from above) is formed. ) A rectangular opening OP is formed. Since this opening OP is used for calibration (calibration) described later, it will be referred to as “calibration opening OP” in the following.

  In the next step 112, the main controller 50 calibrates the objective optical system 94 constituting the wavefront measuring instrument 28 by performing the following steps a. ~ E. Follow the procedure.

a. First, main controller 50 moves reticle stage RST via reticle stage drive unit 12 so that rectangular calibration opening OP formed in measurement reticle RT is positioned on optical axis AX of projection optical system PL. Moving. At the same time, main controller 50 moves wafer stage WST via wafer stage drive unit 27 so that opening 88a of wavefront measuring instrument 28 is positioned on optical axis AX.

b. Next, the main control device 50 is for self-aberration measurement, which is formed on the sign plate 88 of the wavefront measuring device 28 on the image plane of the projection optical system PL based on the detection result of the multipoint focal position detection system (60a, 60b). In order to match the pinhole pattern, the table WTB is slightly driven in the Z-axis direction via the voice coil motors VZ _{1 to} VZ ₃ constituting the wafer stage driving unit 27. At this time, main controller 50 may also finely drive table WTB in the θx and θy directions to adjust the inclination of sign plate 88 as necessary. Until the measurement of the post-adjustment wavefront aberration is completed, main controller 50 servo-controls voice coil motors VZ _{1 to} VZ ₃ with a constant target value and also measures the measured values of Z interferometers 102a to 102c (ie, Based on the height position and the inclination of the guide surface of the stage surface plate 71, the voice coil motors of the first and second vibration isolation mechanisms 56 and 66 are servo-controlled, so that the projection optical system PL, the stage surface plate, , That is, the positional relationship between the projection optical system PL, the table WTB, and the stage 31 (top plate 30) is kept constant.

c. Then, main controller 50 starts the emission of laser light from the light source in illumination system 10. As the laser beam starts to be emitted, the illumination light IL is emitted from the illumination system 10 to the pinhole pattern via the projection optical system PL. Since the calibration opening OP has a sufficiently large opening area, at this time, the projection optical system PL simply functions as an optical system for illuminating the pinhole pattern. By irradiation with the illumination light IL, a spherical wave is generated from the pinhole of the pinhole pattern. Then, this spherical wave becomes a parallel light flux through the objective optical system 94 and irradiates the microlens array MLA. Then, light is condensed on the light receiving surface of the light receiving element 92 by each lens element (microlens) of the microlens array MLA, and a pinhole image of the pinhole pattern is formed on the light receiving surface.

  At this time, if the objective optical system 94 arranged in the middle of the optical path to the light receiving element 92 is an ideal optical system having no wavefront aberration, the parallel light beam incident on the microlens array MLA is a plane wave, The wavefront should be an ideal wavefront. In this case, a spot image (hereinafter also referred to as “spot” as appropriate) is formed at a position on the optical axis of each lens element constituting the microlens array MLA.

  However, since there is usually wavefront aberration in the objective optical system 94, the wavefront of the parallel light beam incident on the microlens array MLA deviates from an ideal wavefront (here, a plane), and the deviation, that is, the ideal wavefront of the wavefront. In accordance with the inclination with respect to, the imaging position of each spot is shifted from the position on the optical axis of each lens element of the microlens array MLA. In this case, the position shift from the reference point of each spot (position on the optical axis of each lens element) corresponds to the inclination of the wavefront. The light (spot image light flux) incident on each condensing point on the light receiving element 92 is photoelectrically converted by the light receiving element 92, and the photoelectric conversion signal is sent to the main controller 50.

d. The main controller 50 calculates the imaging position of each spot on the basis of the sent photoelectric conversion signal, and further uses the calculation result and the position data of a known reference point to detect a positional deviation (Δx, Δy ) Is calculated and stored in the internal memory. Thereby, the calibration of the wavefront measuring instrument 28 is completed.

  In the present embodiment, since the wavefront measuring instrument 28 is separated into the first part 28A and the second part 28B, the relative values of the first part 28A and the second part 28B are measured when measuring the wavefront aberration of the projection optical system PL. However, in the calibration of the wavefront measuring instrument 28 described above, the relative positional deviation between the first portion 28A and the second portion 28B is also caused by the positional deviation of each spot from the reference point. Therefore, the positional deviation between the first portion 28A and the second portion 28B does not matter.

In addition, the positional displacement sensor which detects the relative positional displacement of the 1st housing | casing 86 with which the 1st part 28A is provided, and the 2nd housing | casing 87 with which the 2nd part 28B is provided is the 1st housing | casing 86 and the 2nd housing | casing. The Z / tilt drive mechanisms VZ _{1 to} VZ ₃ may be driven on the basis of the detection result of the misalignment sensor. That is, the Z / tilt drive mechanisms VZ _{1 to} VZ ₃ only need to finely drive the table WTB until the relative displacement between the first housing 86 and the second housing 87 disappears.

When the above calibration is completed, in the next step 113, the main controller 50 positions the first pinhole pattern PH ₁ for measuring the wavefront aberration of the projection optical system on the optical axis AX of the projection optical system PL. In this manner, the reticle stage RST is moved by controlling the reticle stage drive unit 12 while monitoring the measurement value of the reticle interferometer 16. At this time, wafer stage WST moves in the XY plane while maintaining the relative positional relationship between first housing 86 and second housing 87, and pinhole opens 88a of sign plate 88 of wavefront measuring instrument 28. The pattern PH ₁ is positioned on the optical axis AX of the projection optical system PL which is a conjugate position with respect to the projection optical system PL.

As described above, the optical arrangement of each part for the wavefront aberration measurement of the projection optical system PL related to the spherical wave from the first pinhole pattern PH ₁ is completed. The optical arrangement of each part at this time is schematically shown in FIG. As shown in FIG. 9, when the illumination light IL is emitted from the illumination system 10, the light that has reached the first pinhole pattern PH ₁ of the measurement reticle RT is, pinhole pattern PH ₁ becomes a spherical wave Is injected from. Then, after passing through the projection optical system PL, the light is condensed inside the opening 88 a of the sign plate 88 of the wavefront measuring instrument 28. Incidentally, the light passing through the pinhole pattern PH ₂ ~PH _N other than the first pinhole pattern PH _1, does not reach the opening 88a. The wavefront of the light focused on the opening 88a in this way is substantially spherical, but includes the wavefront aberration of the projection optical system PL.

  The light that has passed through the opening 88a is converted into parallel light by the objective optical system 94 and is incident on the microlens array MLA. Here, the wavefront of the light incident on the microlens array MLA reflects the wavefront aberration of the projection optical system PL. That is, when there is no wavefront aberration in the projection optical system PL, as indicated by a broken line in FIG. 9, the wavefront WF is a plane orthogonal to the optical axis AX1, but the projection optical system PL has a wavefront aberration. Is a wavefront WF ′ having a wave as shown by a two-dot chain line in FIG.

The microlens array MLA forms an image (spot image) of the pinhole pattern PH ₁ for each lens element on the optical conjugate plane of the display plate 88, that is, the imaging plane of the light receiving element 92. When the wavefront of the light incident on the lens element (microlens) is orthogonal to the optical axis, a spot image centering on the intersection of the optical axis of the microlens and the imaging surface is formed on the imaging surface. If the wavefront of the light incident on the lens element is tilted, a spot image centered on a point deviated from the intersection of the optical axis of the microlens and the imaging surface is captured by a distance corresponding to the tilt amount. The image is formed on the surface.

  Returning to FIG. 7, next, in step 116, the light receiving element 92 captures images formed on the imaging surfaces. Imaging data obtained by this imaging is sent to the main controller 50 through an electric circuit.

  Next, at step 118, main controller 50 calculates position information of each spot image based on the imaging result. That is, main controller 50 calculates the center of gravity of the light intensity distribution of each spot image formed on the imaging surface of light receiving element 92 by microlens array MLA as the center position, and calculates the center position of each spot image calculated. The position information of each spot image formed on the imaging surface of the light receiving element 92 by the microlens array MLA is stored in the memory.

Next, at step 120, the main controller 50 reads out the position information of each spot image formed on the imaging surface of the light receiving element 92 by the microlens array MLA from the memory, and the first pinhole pattern PH in the measurement reticle RT. _1. Calculate the wavefront aberration of the projection optical system PL for the light via ₁ . In this case, the aforementioned wavefront aberration is calculated in consideration of the calibration result data in step 112. The main control unit 50, thus the coefficients of Zernike polynomials obtained, along with the position of the pinhole pattern PH _1, and stored in memory.

Next, at step 122, main controller 50 determines whether or not the wavefront aberration of projection optical system PL has been calculated for all pinhole patterns. At this stage, since the wavefront aberration of the projection optical system PL is only measured for the first pinhole pattern PH ₁ , the determination here is denied and the process proceeds to step 124.

In step 124, the main controller 50, the opening 91a of marking plate 88 of the wavefront measuring instrument 28, so as to be positioned at a conjugate position relative to the projection optical system PL of the following pinhole pattern PH _2, measurement of wafer interferometer 18 The wafer stage WST is moved via the wafer stage driving unit 27 while monitoring the value, and then the process returns to step 116. In step 124 as well, main controller 50 monitors the displacement in the Z direction of sign plate 88 of wavefront measuring instrument 28 based on the detection results of the multipoint focal position detection system (60a, 60b). When displaced in the Z direction, if the voice coil motors of the first and second vibration isolation mechanisms 56 and 66 are servo-controlled while maintaining the relative positional relationship between the first casing 86 and the second casing 87, good.

Thereafter, the processing of the loop of step → 118 → 120 → 122 → 124 → 116 is repeatedly performed until the determination in step 122 is affirmed. As a result, spot images of the _{2nd to} Nth pinhole patterns PH _{2 to} PH _N are captured, the position of the image is calculated, and the wavefront aberration of the projection optical system PL is sequentially calculated. factor, together with the position of the pinhole pattern PH _1, are stored in the memory.

  When the wavefront aberration of the projection optical system PL is measured for all the pinhole patterns, the determination in step 122 is affirmed, and the series of processing of this routine ends.

  Thereafter, main controller 50 determines whether or not the wavefront aberration of projection optical system PL is less than the allowable value based on the wavefront measurement result data, and as a result of this determination, the wavefront aberration of projection optical system PL is determined. When the value exceeds the allowable value, main controller 50 adjusts projection optical system PL so as to reduce the currently generated wavefront aberration based on the measurement result of the wavefront aberration of projection optical system PL. For this adjustment, the movement of the lens element is controlled via the imaging characteristic correction controller 78, or the movement of the lens element of the projection optical system PL in the XY plane or the replacement of the lens element is performed manually. Is made by

  And after said adjustment, the process according to the above-mentioned flowchart is performed, and the wave aberration of projection optical system PL is measured again. In this way, the measurement of the wavefront aberration of the projection optical system PL and the adjustment of the projection optical system are repeated until the wavefront aberration of the projection optical system PL becomes less than the allowable value.

  Such a process is performed prior to the start of the exposure process. After that, after the preparatory work for reticle exchange, reticle alignment and alignment system baseline measurement, wafer exchange, and wafer alignment (such as EGA) is performed in the same procedure as a normal scanning stepper, Scan exposure is performed, and the pattern of the reticle R is transferred to a plurality of shot areas on the wafer W, respectively. The above reticle exchange, wafer exchange, reticle alignment and alignment system baseline measurement, wafer alignment (eg, EGA), and exposure operation are not different from those in a normal scanning stepper. Is omitted.

  Here, in the above-described step-and-scan exposure, the exposure is performed using the projection optical system PL in which the wavefront aberration is adjusted to an allowable value or less. Therefore, the pattern of the reticle R is set on each wafer W. It is accurately transferred to the shot area.

  Then, the exposed wafer W is unloaded from the wafer holder 25, and thus the exposure process for one wafer W is completed.

  Thereafter, wafer exchange, wafer alignment (such as EGA) preparation work, and step-and-scan exposure are sequentially repeated.

  As described above in detail, according to the present embodiment, the first portion 28A of the wavefront measuring instrument 28 including the objective optical system 94 on which light is incident via the projection optical system PL (projection unit PL) is provided on the table WTB. A stage 31 that is provided and includes at least a detection device 95 that detects light via the objective optical system 94, and a second portion 28B physically separated from the first portion 28A is connected to the table WTB so as to be relatively movable. (Top plate 30). Therefore, the weight of the table WTB provided with the first portion 28A is not increased, and the table WTB can be driven with respect to the stage 31 provided with the relatively heavy second portion 28B. Become. Therefore, the optical characteristic measuring device including the first part and the second part can be permanently installed in the first and second moving bodies, while the table WTB is a first part made of a lightweight member such as an objective optical system. Since only these are provided, weight is not increased. Further, since the second portion can be provided on the stage 31 apart from the projection optical system PL as the test optical system, the heat generated in the second portion 28B is a factor of air fluctuation in the atmosphere around the projection optical system PL. It can be suppressed. Accordingly, the wavefront measuring device 28 is used while controlling the position of the table WTB and the stage 31 using the wafer interferometer 18, the Z interferometers 102a to 102c, the multipoint focus position detection system (60a, 60b), and the like. It becomes possible to measure the wavefront aberration of the projection optical system PL with high accuracy.

  Further, according to the stage apparatus according to the present embodiment, the relatively light first portion 28A is provided on the table WTB that requires high responsiveness and high position controllability at the time of driving, and a relatively heavy detection device. The second portion 28B including 95 is provided on the stage 31 that does not require high responsiveness or high position controllability during driving as compared with the table WTB. Therefore, wavefront measuring instrument 28 can be permanently installed on wafer stage WST, and responsiveness and position controllability required for each of stage 31 and table WTB constituting wafer stage WST can be sufficiently satisfied.

  In addition, since a part of the stage 31 including the second portion 28B can be cooled by the cooling mechanism 150, the heat generated by the detection device 95 included in the second portion 28B is caused by the surrounding members and atmosphere of the second portion 28B. Etc. can be suppressed.

  Further, according to the exposure apparatus 100 of the present embodiment, the optical characteristics of the projection optical system PL can be measured with sufficient accuracy by the wavefront measuring instrument 28, and the projection optical system PL is adjusted based on the measurement result. It becomes possible. Then, the pattern of the reticle R can be accurately transferred onto the wafer W by performing the above-described exposure using the adjusted projection optical system PL. In addition, since the table WTB on which the wafer W is placed has high responsiveness and high position controllability during driving, the surface of the wafer W in the exposure light irradiation region during scanning exposure is in the depth of focus range of the projection optical system. Can be matched within.

In the above embodiment, the microlens array MLA in which a large number of microlenses LS as shown in FIG. 10A are arranged is used. However, the present invention is not limited to this. That is, as shown in FIG. 10B, a microlens array having a combination of a plano-convex lens LS ₁ and a plano-concave lens LS ₂ as a lens element instead of the aforementioned micro lens LS is provided in the micro lens array MLA. It may be used instead. In such a case, the focal distance, that is, the spot movement amount proportional coefficient (substantial focal distance) remains the same value f as in FIG. 10A, and the distance between the microlens array and the light receiving element 92 (installation distance). ) Can be shortened from L0 to L1. In such a case, the second portion 28B of the wavefront measuring instrument can be reduced in size. In addition, as shown in FIG. 10C, a microlens LS ₃ having a convex surface on the light incident side and a concave surface on the light emitting side is replaced with the above-described microlens LS. A microlens array having a lens element may be used. Also in this case, the installation distance can be shortened to L2 while the spot movement amount proportional coefficient is the same f. Also in this case, the second portion 28B can be downsized.

  In the above embodiment, the case where the micro lens array MLA is provided on the second portion 28B side has been described. However, the present invention is not limited to this, and the micro lens array is provided in the first portion 28A. May be.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIG. Here, parts that are the same as or equivalent to those in the first embodiment described above are denoted by the same reference numerals, and a description thereof is simplified or omitted. In the exposure apparatus of the second embodiment, only the configuration of the wavefront measuring instrument is different, and the configuration of the other parts is the same. Accordingly, the following description will focus on differences from the viewpoint of avoiding repeated explanation.

  FIG. 11 shows an internal configuration of the wavefront measuring instrument 28 'according to the second embodiment. The wavefront measuring instrument 28 'is attached to a stepped recess formed in the first portion 28A provided on the side surface of the table WTB and the top plate 30 constituting the stage 31 as in the first embodiment. And a second portion 28B ′ constituting a component of the rectangular plate stage 31.

  As shown in FIG. 11, the second portion 28 </ b> B ′ includes a casing 87 ′, an optical unit 277 provided inside the casing 87 ′, and a detection device 95. The optical unit 277 includes a revolver (rotating device) 77 and microlens arrays MLA1 and MLA2 attached to a rotating unit 79 of the revolver 77. The revolver 77 includes a rotating unit 79 to which the microlens arrays MLA1 and MLA2 are attached, and a drive mechanism 78 that rotationally drives the rotating unit 77. The drive mechanism 78 rotates the rotating unit 79 so that the two microlens arrays MLA1 and MLA2 can be inserted into and removed from the optical path of light through the objective optical system 94 (on the optical path of light during wavefront measurement). Has been.

  As an example, the microlens arrays MLA1 and MLA2 are formed by etching a parallel flat glass plate having the same thickness. In these microlens arrays MLA1 and MLA2, etching processing is performed on a square area in the central portion having substantially the same area to form each lens element. In this case, the number of divisions of the microlens array MLA1 is smaller than the number of divisions of the microlens array MLA2. That is, each lens element of the microlens array MLA1 is larger than each lens element constituting the microlens array MLA2, and its focal length is longer. In consideration of the difference in focal length, the microlens array MLA2 is provided in the rotating unit 79 in a state of being positioned below the microlens array MLA1. For this reason, when inserted in the optical path, the microlens array MLA1 is closer to the light receiving element 92 than the microlens array MLA2. The drive mechanism 78 is controlled by the main controller 50.

  In the second embodiment, the reason why the two microlens arrays MLA1 and MLA2 having different lens element sizes (different numbers of divisions) are provided is as follows.

  That is, if the microlens size in the microlens array is different, that is, the number of divisions in wavefront division is different, the spatial frequency component of the wavefront shape that can be accurately detected, that is, the wavefront aberration component, is different. More specifically, when the size of the microlens (the size of the divided wavefront) is large, the spot image interval is large and the number of pixels per spot image is large, so that accurate spot image position detection is possible. However, due to the averaging effect of the wavefront inclination in the divided wavefront in spot image formation, the measurement accuracy for the component having a high spatial frequency of the wavefront shape in the divided wavefront is lowered.

  On the other hand, when the size of the microlens is small, the spot image interval is small, the number of pixels per spot image is small, and the spot image position cannot be accurately detected. Although the measurement accuracy for a component with a low spatial frequency and a low spatial frequency decreases, the spot image interval is small, and even if the number of pixels per spot image is reduced, a component with a high spatial frequency is adjacent. Since the difference in slope between the matching split wavefronts is large and the deviation from the ideal spot position increases, even if the detection accuracy of the spot image position decreases, the measurement accuracy of the wavefront shape that focuses on the deviation amount does not decrease so much Highly accurate measurement is possible.

  Therefore, by performing wavefront aberration measurement of the projection optical system PL using the microlens array MLA1 and wavefront aberration measurement of the projection optical system PL using the microlens array MLA2, the wavefront division by a single division number is performed. It is possible to obtain an accurate measurement result of the wavefront shape in a wide spatial frequency range that could not be obtained. Thereby, the wavefront aberration of the projection optical system PL can be accurately measured.

  The structure of other parts is the same as that of the first embodiment described above.

  According to the exposure apparatus of the second embodiment configured as described above, effects equivalent to those of the first embodiment described above can be obtained, and projection can be performed with higher accuracy than the first embodiment. The wavefront aberration of the optical system PL can be measured. Then, by adjusting the projection optical system PL based on the measurement data of the wavefront aberration of the projection optical system PL measured with high accuracy, the projection optical system PL can be adjusted with higher accuracy, and as a result, higher accuracy. Exposure can be realized.

  In the second embodiment, the rotating unit 79 is provided with two types of microlens arrays. However, the present invention is not limited to this, and three or more types of microlens arrays may be provided. Further, instead of the microlens array or together with the microlens array, a polarization optical element for detecting the polarization state of the illumination light may be provided in the rotating unit 79.

  In each of the above embodiments, the Z interferometers 102a to 102c are provided, and the focus position detection system (60a, 60b) and the Z interferometers 102a to 102c are used together when measuring the wavefront aberration. Since the positional relationship between the projection optical system PL and the table WTB can be adjusted only by the position detection system (60a, 60b), the Z interferometer is not necessarily provided.

  In each of the above embodiments, the case where each part of the wavefront measuring instrument 28 is provided at the end of the table WTB and the stage 31 is described. However, the present invention is not limited thereto, and is embedded in a place other than the end of the table WTB and the stage 31. It may be provided in the state.

In each of the above embodiments, the case where the present invention is applied to a scanning stepper has been illustrated. However, the scope of the present invention is not limited to this, and the present invention provides a stationary mask and substrate. The present invention can also be suitably applied to a stationary exposure apparatus such as a stepper that performs exposure in such a state. The present invention can also be suitably applied to a step-and-stitch type exposure apparatus.
Further, the magnification of the projection optical system in the exposure apparatus of each of the above embodiments may be not only a reduction system but also an equal magnification and an enlargement system, and the projection optical system PL is not only a refraction system but also a reflection system and a catadioptric system. Either of them may be used, and the projected image may be either an inverted image or an erect image.

  Further, the object to be exposed by the exposure apparatus is not limited to a wafer for semiconductor manufacturing as in the above-described embodiment. For example, the object for manufacturing a display apparatus such as a liquid crystal display element, a plasma display, or an organic EL is used. It may be a substrate for manufacturing a rectangular glass plate, a thin film magnetic head, an image sensor (CCD or the like), a mask or a reticle.

In each of the above embodiments, the case where ArF excimer laser light (193 nm) is used as exposure illumination light has been described. However, the present invention is not limited to this, and KrF excimer laser light (248 nm), F ₂ laser light (157 nm), g-line (436 nm), i-line (365 nm), Ar ₂ laser light (126 nm), copper vapor laser, high-frequency wave of YAG laser, or the like can be used as illumination light for exposure. Further, for example, as the vacuum ultraviolet light, a single wavelength laser beam oscillated from a DFB semiconductor laser or a fiber laser is a single wavelength laser light, for example, erbium (Er) (or both erbium and ytterbium (Yb)). It is also possible to use a harmonic that is amplified by a doped fiber amplifier and wavelength-converted to ultraviolet light using a nonlinear optical crystal.

  Further, in each of the above embodiments, the case where the present invention is applied to an exposure apparatus for manufacturing a semiconductor has been described. However, the present invention is not limited to an exposure apparatus for manufacturing a semiconductor, but a display including a liquid crystal display element or the like. , An exposure apparatus for transferring a device pattern onto a glass plate, an exposure apparatus for transferring a device pattern used for manufacturing a thin film magnetic head onto a ceramic wafer, and an image sensor (CCD, etc.), organic EL, micromachine, DNA The present invention can also be applied to an exposure apparatus used for manufacturing a chip or the like. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern. Here, in an exposure apparatus using DUV (far ultraviolet) light, VUV (vacuum ultraviolet) light, or the like, a transmission type reticle is generally used. As a reticle substrate, quartz glass, fluorine-doped quartz glass, meteorite, Magnesium fluoride or quartz is used. Further, in a proximity type X-ray exposure apparatus or an electron beam exposure apparatus, a transmission mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate. Furthermore, the present invention is also applied to an immersion type exposure apparatus that is disclosed in, for example, International Publication WO99 / 49504 pamphlet and the like in which a liquid (for example, pure water) is filled between the projection optical system PL and the wafer. Can do.

  In addition, an illumination optical system and a projection optical system composed of a plurality of lenses are incorporated into the exposure apparatus for optical adjustment, and a reticle stage RST, wafer stage WST, and the like made up of a large number of parts are attached to the body of the exposure apparatus for wiring, The exposure apparatus of the above-described embodiment can be manufactured by connecting piping and further performing general adjustment (electrical adjustment, operation check, etc.). The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  For semiconductor devices, the step of designing the function and performance of the device, the step of manufacturing a reticle based on this design step, the step of manufacturing a wafer from a silicon material, and transferring the reticle pattern to the wafer by the exposure apparatus of the above-described embodiment And a device assembly step (including a dicing process, a bonding process, and a packaging process), an inspection step, and the like.

  As described above, the optical characteristic measuring apparatus and the stage apparatus of the present invention are suitable for measuring the optical characteristics of the optical system to be tested. The exposure apparatus of the present invention is suitable for exposing an object with exposure light via a projection optical system and transferring a predetermined pattern onto the object.

1 is a schematic view showing an exposure apparatus according to a first embodiment of the present invention. It is a perspective view which shows a wafer stage. It is a top view which shows the wafer stage vicinity. It is sectional drawing which shows the internal structure of the wavefront measuring device which concerns on 1st Embodiment. It is a figure which shows a cooling mechanism. It is a figure which shows the control system of 1st Embodiment. It is a flowchart for demonstrating the measurement operation | movement of the wavefront aberration of the projection optical system in an on-body performed in the exposure apparatus of 1st Embodiment. It is a figure which shows the example of the pattern for a measurement formed in the reticle for a measurement. It is a figure for demonstrating the optical arrangement | positioning at the time of the imaging of the spot image in 1st Embodiment. FIG. 10A is a diagram showing a microlens (lens element) constituting the microlens array according to the first embodiment, and FIGS. 10B and 10C are lenses according to modifications. It is a figure which shows an element. It is sectional drawing which shows the internal structure of the wavefront measuring device which concerns on 2nd Embodiment.

Explanation of symbols

27 ... Wafer stage drive unit (drive system), 28 ... Wavefront measuring device (optical characteristic measuring device), 28A ... First part, 28B ... Second part, 31 ... Stage (second moving body), 50 ... Main control Device (control device) 71 ... Stage platen 94 ... Objective optical system 95 ... Detection device 100 ... Exposure device 102a-102c ... Z interferometer (measuring mechanism) 150 ... Cooling mechanism 277 ... Optical unit MLA: micro lens array (wavefront dividing optical element), PL: projection optical system (test optical system), W: wafer (object), WST: wafer stage (moving body), WTB: table (first moving body) .

Claims (12)

An optical property measuring apparatus for measuring optical properties of a test optical system,
A first portion including an objective optical system that is provided on the first moving body and into which light through the optical system to be detected enters;
A detection device that is provided on a second moving body connected to the first moving body so as to be relatively movable and is physically separated from the first portion and detects light via the objective optical system. And a second part including at least an optical property measuring device.   One of the first part and the second part includes a wavefront splitting optical element that splits a wavefront of light that passes through the objective optical system, and polarization optics, disposed between the objective optical system and the detection device. The optical characteristic measuring apparatus according to claim 1, further comprising an optical unit having at least one of the elements.   The optical characteristic measuring apparatus according to claim 2, wherein the optical unit is included in the second portion.   4. The optical characteristic measuring apparatus according to claim 2, wherein at least one of the wavefront splitting optical element and the polarizing optical element is freely inserted into and removed from the optical path of the light. The optical unit has a revolver,
The optical characteristic measuring apparatus according to claim 4, wherein at least one of the wavefront splitting optical element and the polarizing optical element is provided in the revolver. The optical unit has a plurality of wavefront splitting optical elements,
The optical characteristic measuring apparatus according to claim 5, wherein the plurality of wavefront dividing optical elements have different numbers of divisions.   Each of the plurality of split elements constituting the wavefront splitting optical element is characterized in that the surface on which the light is incident is a convex surface and the surface on which the light is emitted is a concave surface. The optical characteristic measuring apparatus as described in any one of 2-6.   The optical characteristic measuring apparatus according to claim 7, wherein each of the plurality of splitting elements constituting the wavefront splitting optical element is configured by a combination of a plano-convex lens and a plano-concave lens. A moving body including a stage that moves in a two-dimensional plane, and a table that is movable on the stage in a direction orthogonal to at least the two-dimensional plane;
A drive system for driving the movable body;
A stage apparatus comprising: the optical part measuring apparatus according to any one of claims 1 to 8, wherein the first part is provided on the table and the second part is provided on the stage.   The stage apparatus according to claim 9, further comprising a cooling mechanism that is provided on the stage and cools at least a part of the stage including the second part. An exposure apparatus that exposes an object with exposure light via a projection optical system and transfers a predetermined pattern onto the object,
An exposure apparatus comprising the stage device according to claim 9 or 10, wherein the object is placed on the table, and the projection optical system is the optical system to be measured of the optical property measurement apparatus. A stage surface plate on which a movement reference plane of the stage is formed;
A measuring mechanism that measures information about a position of the movement reference plane with respect to a plane perpendicular to the optical axis of the projection optical system and an optical axis direction;
A control device that adjusts a positional relationship between the projection optical system and the stage surface plate based on a measurement result of the measurement mechanism when the optical property measurement apparatus measures the optical characteristics of the projection optical system; The exposure apparatus according to claim 11 provided.

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