JP2006120964A - Aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a high accurate imprint of pattern to wafer top which is not influenced by a difference of control state generated by a difference of drive state with respect to a stage of table, such as reciprocal difference of AF or the like. <P>SOLUTION: A stage 28 is transferred by a controlling unit 20 in order to maintain a designated location relation between a wafer W and a reference face, while a table WTB is driven in an optical axis AX and an inclination directions of projection optical system PL through actuators 21A, 21B or the like. Detection values of sensors 21A, 21B or the like, detecting a driven amount of table with respect to the stage, are acquired by the controlling unit 20 under a transfer of the stage. Then, on the basis of the detection value of the sensor, a location of the wafer W is controlled relating to the optical axis AX and the inclination directions. Therefore, the imprint is not influenced by the difference of the control state generated by the difference of the drive state with respect to the stage of the table. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus, and more particularly to an exposure apparatus used in a lithography process when manufacturing an electronic device such as a semiconductor element (integrated circuit) or a liquid crystal display element.

  In a lithography process for manufacturing an electronic device such as a semiconductor element (such as an integrated circuit) or a liquid crystal display element, a mask (or reticle) pattern image is applied to a wafer coated with a resist (photosensitive agent) via a projection optical system, or Step-and-repeat reduction projection exposure apparatus (so-called stepper) that transfers to each of a plurality of shot areas on an object such as a glass plate (hereinafter referred to as “wafer”), or step-and-scan projection. An exposure apparatus (a so-called scanning stepper (also called a scanner)) or the like is mainly used.

  In this type of projection exposure apparatus, with the miniaturization of patterns due to the high integration of integrated circuits, higher resolution (resolution) is required year by year. In order to meet the demand for improvement in resolution, exposure light is used. And the numerical aperture (NA) of the projection optical system (NA) gradually increased, and as a result, the depth of focus of the projection optical system gradually decreased.

  Therefore, in a recent projection exposure apparatus, a positional deviation of the wafer surface with respect to the image plane of the projection optical system is obliquely incident, for example, for each shot area on the wafer (in the case of a stepper) or sequentially (in the case of a scanning stepper). The position shift is detected by driving the wafer table (or wafer stage) on which the wafer is placed on the optical axis direction of the projection optical system based on the detection result. It is corrected in real time.

  By the way, in a recent projection exposure apparatus, the stage surface plate that supports the wafer stage is physically separated from the main frame that holds the projection optical system and is installed below the projection optical system (hereinafter, for convenience). "Stage surface plate separate type") is used relatively often (see, for example, Patent Document 1 and Patent Document 2). In the case of a scanning and stepper separately placed on the stage surface plate, when the focus and leveling control during exposure is performed, if the wafer surface on the wafer table is separated from the image plane of the projection optical system, the focus and leveling control is performed. At this time, it takes a long time to drive the wafer surface position, or a delay in driving occurs, resulting in a decrease in throughput or exposure accuracy. Therefore, at the time of exposure, it is desirable that the wafer surface is positioned in the vicinity of the image plane of the projection optical system PL.

  In view of this point, in the current scanning stepper, the alignment between the AF surface and the wafer table upper surface, that is, the adjustment for making the AF surface and the moving surface (running surface) of the wafer stage parallel is performed as follows. Running. Here, the AF plane means a virtual reference plane defined when the outputs of a plurality of sensors of the multipoint focal position detection system in which the offset between sensors is adjusted are all reference values (for example, zero). .

  First, each sensor of the multipoint focus position detection system is calibrated in advance so that the best focus position is the origin, and the above-mentioned AF surface is made to coincide with the image plane of the projection optical system. Then, using a multipoint focus position detection system, surface position information of a reference plane plate on the wafer table (this surface position is located on the same plane as the wafer surface position on the wafer table) is measured. Then, by adjusting the height position of the stage surface plate based on this measurement result, the surface position of the reference plane plate is made to coincide with the AF surface, that is, the AF surface and the moving surface (running surface) of the wafer stage are parallel. Adjustments to be made have been performed.

  However, in the above adjustment method, the driving state of the wafer table with respect to the wafer stage (for table driving) due to the difference in the position of the shot area to be exposed on the wafer, that is, the difference in the position of the wafer stage on the stage surface plate. For example, the difference between the shots of the running surface caused by the difference in the driving state of each actuator cannot be corrected. As a result, depending on whether the shot area is a positive scan or a negative scan, There is a disadvantage that a corresponding difference in focus control (a forward / backward difference in AF) appears.

JP 2001-291663 A US Pat. No. 6,690,450

  The present invention has been made under the circumstances described above. From the first viewpoint, the exposure for transferring the pattern formed on the mask (R) onto the object (W) via the projection optical system (PL). A stage (28) that moves in a plane orthogonal to the optical axis of the projection optical system; a table (WTB) on which the object is placed; and the projection optical system on the stage. A driving mechanism (21A to 21C) capable of driving in an optical axis direction of the system and an inclination direction with respect to a plane orthogonal to the optical axis; and a sensor (23A to 23C) for detecting a driving amount of the table with respect to the stage by the driving mechanism And moving the stage while driving the table in at least one of the optical axis direction and the tilt direction via the drive mechanism in order to maintain a predetermined positional relationship between the object and a reference plane. The control device (20) that acquires the detection value of the sensor during the movement and controls the position of the object in at least one of the optical axis direction and the tilt direction based on the acquired detection value of the sensor. And an exposure apparatus including:

  According to this, in order to maintain the predetermined positional relationship between the object and the reference plane, the control device causes the table to move at least in the optical axis direction of the projection optical system and the inclination direction with respect to the plane orthogonal to the optical axis. The stage is moved while driving in one direction. In addition, a detection value of a sensor for detecting the driving amount of the table with respect to the stage by the driving mechanism is acquired by the control device while the stage is moving, and the acquired detection value of the sensor (that is, the driving amount of the table with respect to the stage). The position of the object in at least one direction of the optical axis direction and the tilt direction is controlled based on.

  In this case, the control device can know the driving state of the table stage based on the detection value of the sensor, and relates to at least one of the optical axis direction and the tilt direction based on the control state corresponding to the driving state. By controlling the position of the object, a predetermined positional relationship between the object and the reference plane is maintained.

  Therefore, for example, when the pattern formed on the mask is transferred onto the object via the projection optical system, the above-mentioned reference plane is the best image plane of the pattern by the projection optical system or a surface substantially coinciding with this. As a result, when the control device performs the above-described control, it is possible to realize the transfer of the pattern onto the object without being affected by the difference in the control state caused by the difference in the drive state with respect to the table stage.

<< 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 the first embodiment. 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 a reticle R as a mask with illumination light (exposure light) IL, a reticle stage RST as a mask stage on which the reticle R is placed, and projection optics. A projection unit PU including a system PL, a wafer stage WST on which a wafer W as an object is placed, a body BD on which the reticle stage RST and the projection unit PU are mounted, a control system thereof, and the like are provided.

  The illumination system 10 includes, for example, an illuminance uniformizing optical system including a light source, an optical integrator, a beam splitter, and the like as disclosed in Japanese Patent Application Laid-Open No. 2001-313250 (corresponding to US Patent Application Publication No. 2003/0025890). It includes a relay lens, a variable ND filter, a reticle blind, etc. (all not shown). In the illumination system 10, the slit-shaped illumination area IAR on the reticle R defined by the reticle blind is illuminated with the illumination light IL with a substantially uniform illuminance. 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 vacuum suction (or electrostatic suction). The reticle stage RST is two-dimensionally (in the X-axis direction, the Y-axis direction, and the XY plane) in an XY plane perpendicular to the optical axis AX of the projection optical system PL, which will be described later, by a reticle stage drive unit 12 including a linear motor. It can be driven slightly (in the direction of rotation around the orthogonal Z axis (θz direction)), and the reticle base 36 is designated as a predetermined scanning direction (here, the Y axis direction that is the orthogonal direction to the paper surface in FIG. 1). It can be driven at the scanning speed set.

  The reticle stage RST is actually a reticle coarse movement stage that can be driven in a predetermined stroke range in the Y-axis direction on the reticle base 36 by a linear motor, and at least three actuators (for example, voice coils) for the reticle coarse movement stage. 1 is shown as a single stage for the sake of convenience of illustration. FIG. 1 shows a reticle fine movement stage that can be finely driven in the X-axis direction, Y-axis direction, and θz direction by a motor or the like. Accordingly, in the following, the reticle stage RST is a single stage that can be finely driven in the X-axis direction, the Y-axis direction, and the θz direction by the reticle stage drive unit 12 and that can be scanned in the Y-axis direction. Will be described.

  In the case of this embodiment, measures are taken to reduce as much as possible the influence of vibration caused by the reaction force acting on the stator of the linear motor when the reticle stage RST is driven (particularly during scanning drive). Specifically, the stator of the linear motor described above is provided separately from the body BD as disclosed in, for example, JP-A-8-330224 (corresponding US Pat. No. 5,874,820). The reaction force that is supported by a support member (reaction frame) (not shown) and acts on the stator of the linear motor when the reticle stage RST is driven is transmitted to the floor F of the clean room via the reaction frame. It is supposed to be escaped. In addition, for example, a reaction force canceling mechanism using a momentum conservation law disclosed in Japanese Patent Laid-Open No. 8-63231 (corresponding US Pat. No. 6,246,204) is used as a reaction force canceling mechanism for reticle stage RST. It may be adopted.

  The position of the reticle stage RST in the stage moving surface is always detected by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 16 via a movable mirror 15 with a resolution of about 0.5 to 1 nm, for example. Yes. In this case, position measurement is performed with reference to the fixed mirror 14 fixed to the side surface of the lens barrel 40 constituting the projection unit PU. Here, actually, a Y moving 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 are provided on the reticle stage RST. Correspondingly, a reticle Y interferometer and a reticle X interferometer are provided, and correspondingly, a fixed mirror for X-axis direction position measurement and a fixed mirror for Y-axis direction position measurement 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 the reticle interferometer 16 is supplied to the stage control device 20 and the main control device 50 via this, and the stage control device 20 measures the measurement value of the reticle interferometer 16 in response to an instruction from the main control device 50. Based on the above, the reticle stage RST is driven and controlled via the reticle stage drive unit 12.

  Above the reticle R, light having an exposure wavelength for simultaneously observing the pair of reference marks on the wafer stage WST and the pair of reticle marks on the reticle R corresponding to the pair via the projection optical system PL is used. A pair of reticle alignment systems 13A and 13B (not shown in FIG. 1, refer to FIG. 4) composed of a TTR (Through The Reticle) alignment system are provided at a predetermined distance in the X-axis direction. As this pair of reticle alignment systems, for example, one having the same configuration as that disclosed in Japanese Patent Laid-Open No. 7-176468 (corresponding US Pat. No. 5,646,413) is used.

  The projection unit PU is held by a part of the body BD below the reticle stage RST in FIG. The body BD includes a first column (main frame) 32 provided on a frame caster FC installed on a floor F of a clean room, and a second column 34 fixed on the first column 32. I have.

  The frame caster FC includes a base plate BS placed horizontally on the floor surface F, and a plurality of, for example, three (or four) leg portions 39 (provided on the paper surface in FIG. 1) fixed on the base plate BS. The rear leg is not shown).

  The first column 32 has a plurality of (herein, three first vibration isolation mechanisms 56A, 56B, 56C) fixed to the upper ends of the plurality of leg portions 39 constituting the frame caster FC (here, FIG. 1). Then, the first anti-vibration mechanism 56C on the back side of the paper surface is supported substantially horizontally by a not-shown illustration (see FIG. 4).

  The first column 32 is made of, for example, a casting, and a circular opening (not shown) is formed at a substantially central portion thereof. The projection unit PU is inserted into the circular opening from above and supported by the first column 32 via a flange FLG provided in the vicinity of the lower end portion of the outer periphery thereof.

  On the upper surface of the first column 32, one end (lower end) of a plurality of, for example, three legs 41 (however, the legs on the back side in FIG. 1 are not shown) is fixed at a position surrounding the projection unit PU. ing. 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 a projection optical system as an exposure optical system that includes a lens barrel 40 that is cylindrical and has a flange FLG in the vicinity of the lower end of the outer periphery thereof, and a plurality of optical elements that are held by the lens barrel 40. It is comprised by 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). Therefore, when the reticle R is illuminated by the illumination light IL from the illumination system 10, the illumination light IL that has passed through the reticle R is irradiated with the illumination light IL via the projection optical system PL. A reduced image of the circuit pattern of the reticle R (a reduced image of a part of the circuit pattern) is formed on the wafer W whose surface is coated with a resist (photosensitive agent). Here, the wafer W is a disk-shaped substrate such as a semiconductor (silicon or the like) or SOI (Silicon Insulator), for example, and a resist (photosensitive agent) is applied thereon.

  Wafer stage WST is levitated and supported on the upper surface of stage base 71 as a surface plate disposed horizontally below projection unit PU in a non-contact manner via a plurality of air bearings provided on the bottom surface.

  The stage base 71 includes a plurality of (for example, three) support members 73 respectively disposed at a plurality of locations (for example, three locations) on a flat plate MP called a maintenance plate installed on the base plate BS. A plurality (for example, three) of second anti-vibration mechanisms 66A to 66C fixed to the upper surface of the support member 73 (however, in FIG. 1, the second anti-vibration mechanism 66C on the back side of the drawing is not shown, see FIG. 4) Is supported almost horizontally.

  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 moving surface (running surface) of the wafer stage WST.

  Wafer stage WST is below projection unit PU in FIG. 1 along the guide surface by XY drive unit 29 (not shown in FIG. 1, refer to FIG. 3) including an actuator such as a linear motor (or a planar motor). An XY stage 28 as a stage driven in the XY plane and three Z position driving units 38A to 38C on the XY stage 28 (however, the Z position driving unit 38C on the back side of the drawing is not shown in FIG. 3) and a wafer table WTB as a table supported at three points. Wafer W is fixed to the upper surface of wafer table WTB by vacuum chucking (or electrostatic chucking) or the like via wafer holder WH.

  The XY stage 28 is levitated and supported above an upper surface of the stage base 71 by an air bearing (not shown) through a clearance of about several μm, for example, and is scanned in the scanning direction by a linear motor (not shown) constituting the XY drive unit 29. It is configured to be capable of two-dimensional driving in a certain Y-axis direction (a direction perpendicular to the paper surface in FIG. 1) and an X-axis direction (a horizontal direction in the paper surface in FIG. 1) perpendicular thereto.

  The Z position driving units 38A to 38C are actuators (for example, voice coils) as three driving mechanisms for independently driving the respective support points on the lower surface of the wafer table WTB in the optical axis direction (Z axis direction) of the projection optical system PL. Motors) 21A to 21C (however, in FIG. 1, the actuator 21C on the back side of the paper is not shown, see FIG. 4), and the drive amount (from the reference position) of each support point by each of these actuators 21A to 21C Encoders 23A to 23C (however, in FIG. 1, the encoder 23C on the back side of the drawing is not shown, see FIG. 4).

As the encoders 23A to 23C, for example, optical or electrostatic encoders can be used. In the present embodiment, the actuators 21A to 21C cause the wafer table WTB to be tilted with respect to the optical axis AX direction (Z-axis direction) and the plane orthogonal to the optical axis (XY plane), that is, θx that is the rotational direction around the X axis. A driving mechanism is configured to drive in the direction θy, which is the direction of rotation around the Y axis. Further, the driving amount (displacement from the reference point) of each support point by the actuators 21A to 21C of the wafer table WTB measured by the encoders 23A to 23C is the stage controller 20 and the main controller 50 via this. To be supplied. The measured values of the encoders 23A, 23B, and 23C are Z _21A , Z _21B , and Z _21C .

  A reference mark plate FM is provided on the wafer table WTB so that the surface thereof is substantially the same height as the wafer W. On the surface of the reference mark plate FM, there is at least a pair of reticle alignment first reference marks and a baseline measurement of an off-axis alignment system, which will be described later, having a known positional relationship with respect to the first reference marks. The second reference mark is formed.

  The positional information in the XY plane of the wafer table WTB (wafer stage WST) is, for example, with a resolution of about 0.5 to 1 nm by an interferometer system 18 that irradiates a length measuring beam to a movable mirror 17 fixed on the upper part. Always detected. The interferometer system 18 is fixed to the first column 32 in a suspended state, and the reflection surface of the movable mirror 17 is based on the reflection surface of the fixed mirror 57 fixed to the side surface of the lens barrel 40 constituting the projection unit PU. Is measured as position information of wafer stage WST. As the interferometer system 18, for example, a heterodyne Michelson interferometer is used.

  Here, on the wafer table WTB, actually, as shown in FIG. 2, the Y movable mirror 17Y having a reflecting surface orthogonal to the Y-axis direction that is the scanning direction and the X-axis direction that is the non-scanning direction. An X movable mirror 17X having an orthogonal reflecting surface is provided, and correspondingly, a fixed mirror and a laser interferometer are provided for measuring the X-axis direction position and for measuring the Y-axis direction position, respectively. In FIG. 1, these are typically shown as a movable mirror 17, a fixed mirror 57, and an interferometer system 18. For example, the end surface of wafer table WTB may be mirror-finished to form a reflecting surface (corresponding to the reflecting surfaces of movable mirrors 17X and 17Y).

  Also, the wafer table WTB has a reference plane plate used for adjusting the offset between sensors of the multipoint focus position detection system, which will be described later (this surface position is substantially the same as the surface position of the wafer on the wafer table). Etc.) are also provided.

As shown in FIG. 2, the interferometer system 18 includes a Y-axis interferometer 18Y and two X-axis interferometers 18X ₁ and 18X ₂ .

From the Y-axis interferometer 18Y, the Y-axis is arranged symmetrically with respect to the Y-axis passing through the optical axis AX of the projection optical system PL in plan view (viewed from above), passing through the XY plane substantially the same as the surface of the wafer W. A pair of length measuring beams (measuring light) each having the optical axes LWY _L and LWY _R in the direction are irradiated on the Y moving mirror 17Y. The Y-axis interferometer 18Y irradiates a Y fixed mirror (not shown) with a reference beam that passes above the optical axes LWY _L and LWY _R and has an optical axis in the Y-axis direction orthogonal to the optical axis AX. . The distance between the optical axis LWY _L and the optical axis LWY _R is 2D.

From the X-axis interferometer 18X ₁ , a reference beam having an optical axis in the X-axis direction that passes through substantially the same XY plane as the reference beam irradiated to the Y fixed mirror and is orthogonal to the optical axis of the projection optical system PL. Irradiated to an X fixed mirror (not shown). Further, from the X axis interferometer 18X _1, located below the reference beam, the measuring beam X movable mirror having an optical axis LWX _B in the X-axis direction overlaps with the optical axis of the reference beam in a plan view 17X Has been irradiated.

Meanwhile, the from X-axis interferometer 18X _2, through the same XY Menjo as the reference beam, and the reference beam with the optical axis of the X-axis direction passing through the detection center of the off-axis alignment system ALG is an alignment system ALG Irradiated to a fixed X-fixed mirror (not shown). Further, from this X-axis interferometer 18X ₁ , a measurement beam having an optical axis LWX _M in the X-axis direction passing through the substantially same XY plane as the optical axis LWX _B and passing through the detection center of the alignment system ALG is moved by X. The mirror 17X is irradiated.

The measurement values (outputs) of the Y-axis interferometer 18Y and the two X-axis interferometers 18X ₁ and 18X ₂ are supplied to the stage controller 20 and the main controller 50 through this.

In the present embodiment, the position of the wafer table WTB in the Y-axis direction is determined by the stage controller 20 and the main controller based on the average values of the measured values WY _L and WY _R of the optical axes LWY _L and LWY _R of the Y-axis interferometer 18Y. 50. Further, based on the difference between the measured values of the optical axes LWY _L and LWY _R of the Y-axis interferometer 18Y and the optical axis interval 2D, the position information of the wafer table WTB (ie, yawing) about the rotation direction (θz direction) around the Z axis. Information) is measured by the stage controller 20 and the main controller 50.

Further, based on the measured value WX _B of the optical axis LWX _B of the X-axis interferometer 18X ₁ , the position of the wafer table WTB in the X-axis direction is measured by the stage controller 20 and the main controller 50.

Further, based on the measurement value WX _M of the optical axis LWX _M of the X-axis interferometer 18X ₂ , the position information of the wafer table WTB in the X-axis direction is measured by the stage controller 20 and the main controller 50.

The stage control device 20 and the main control device 50 use the alignment system ALG to detect an alignment mark (wafer mark) on the wafer W, based on the measurement value WX _M of the X-axis interferometer 18X _2. Then, the X position information of the wafer table WTB is measured, but at the time of exposure other than that, the X position information of the wafer table WTB is measured based on the measured value WX _B of the X axis interferometer 18X ₁ . Therefore, it is possible to measure the X position information of wafer table WTB (wafer stage WST) without any so-called Abbe error both during exposure and during wafer alignment.

Incidentally, LWY optical axis from the Y axis interferometer 18Y _L, LWY _R optical axis LWY _L are as viewed from the lower, another measurement beam along the optical axis overlap each LWY _R Whereas Y movable mirror 17Y It is irradiated. Similarly, of the respective X-axis interferometer 18X _1, 18X _2, the optical axis LWX _B, through the lower LWX _M, another measurement along the optical axis overlap each optical axis LWX _B, the LWX _M in plan view A long beam is applied to the X moving mirror 17X. Therefore, in this embodiment, the θx rotation (pitching) of the wafer table WTB can be measured based on the output of the Y-axis interferometer 18Y, and at the time of exposure based on the measurement values of the X-axis interferometers 18X ₁ and 18X _2. The θy rotation (rolling) of the wafer table WTB during alignment can be measured. However, the pitching and rolling measurement results are not used for correcting the pitching and rolling of the wafer table WTB, but for correcting the position error of the wafer table WTB in the Y-axis direction and the X-axis direction due to these. Therefore, in the following, description of pitching and rolling measurement of wafer table WTB by interferometer system 18 is omitted.

As described above, the interferometer system 18, three interferometers 18Y, is configured to include a 18X _1, 18X _2, interferometer system 18 measures positional information of wafer table WTB as described above, one It can be thought of as a system. Therefore, in the following description, unless particularly required, the interferometer system 18 will be described as a single system capable of measuring position information regarding the X, Y, and θz directions of the wafer table WTB.

  In stage control device 20, in accordance with an instruction from main control device 50, based on position information (or speed information) of wafer table WTB (wafer stage WST), the XY surface of wafer stage WST is passed through XY drive unit 29. Control the position within.

  FIG. 3 is a partial cross-sectional view showing a component near one end of the stage base 71. The second anti-vibration mechanisms 66A to 66C typically take one of the second anti-vibration devices 66A, and as shown in FIG. 3, an air mount 80 that supports a stage base 71, and a stage base 71 is provided with a micro drive unit 87 capable of micro drive with high response in the Z-axis direction (vertical direction in the plane of the drawing in FIG. 3 (coincidence with the gravity direction)).

  The air mount 80 is connected to a housing 82 having an opening in the upper part, a holding member 83 provided so as to close the opening of the housing 82, and the housing 82 and the holding member 83. 83, a diaphragm 85 that forms a gas chamber 84 in a substantially airtight state, and an electromagnetic regulator 86 that adjusts the pressure of gas, for example, air, filled in the gas chamber 84. In this case, the stage base 71 is held via the holding member 83 by the pressure of the air inside the gas chamber 84.

  The micro drive unit 87 is a stator that generates electromagnetic force that drives the stage base 71 in the Z-axis direction by performing electromagnetic interaction between the mover 87a directly attached to the stage base 71 and the mover 87a. A voice coil motor 87 having a power supply 87b, and a current supply source 88 for supplying a drive current to the voice coil motor 87.

  In the second vibration isolation mechanism 66A configured as described above, the electromagnetic regulator 86 is controlled based on the measurement value of a pressure sensor (not shown) by a controller (not shown), and pressure control of the gas in the gas chamber 84, for example, air. Is done. When high response control is required, the controller controls the voice coil motor 87 according to the output of an accelerometer (not shown) attached to the stage base 71. Further, a controller (not shown) controls the voice coil motor 87 or the electromagnetic regulator 86 based on a command from the stage control device 20. Further, fine vibration such as floor vibration transmitted through the base plate BS and the flat plate MP is isolated by the air spring of the air mount 80 (insulated at the micro G level). The remaining second vibration isolation mechanisms 66B and 66C are configured in the same manner as the second vibration isolation mechanism 66A and function in the same manner.

  Further, each of the three first vibration isolation mechanisms 56A to 56C is configured in the same manner as the above-described second vibration isolation mechanism 66A except that the object to be supported is different, and thus detailed description thereof is omitted.

In the present embodiment, the stage base 71 is moved in the optical axis AX direction (Z) under the instruction of the main controller 50 and the stage controller 20 by the second vibration isolation mechanisms 66A to 66C that support the stage base 71 at three points. A driving device is configured to drive in an inclination direction with respect to a plane (XY plane) orthogonal to the optical axis and the optical axis, that is, a θx direction that is a rotation direction around the X axis and a θy direction that is a rotation direction around the Y axis. . The drive amount (displacement from the reference point) of each support point of the stage base 71 by the second vibration isolation mechanisms 66A to 66C is, for example, the level of the stage base 71 with respect to the reference position provided on the flat plate MP or the support member 73. It is measured by displacement sensors 64A to 64C (not shown in FIG. 3, refer to FIG. 4) that detect the displacement of each support point in the Z-axis direction, and is supplied to the main controller 50. Here, as the displacement sensors 66A to 66C, for example, optical or electrostatic displacement sensors can be used, and the displacements of the respective support points to be measured are (Z _66A , Z _66B , Z _66C ) and To do.

  Returning to FIG. 1, the lower surface of the first column 32 is disclosed in, for example, Japanese Patent Laid-Open No. 6-283403 (corresponding US Pat. No. 5,448,332) comprising an irradiation system 42a and a light receiving system 42b. An oblique incidence type multi-point focus position detection system (hereinafter also referred to as “multi-point AF system” as appropriate) is provided. Thus, the irradiation system 42a, the light receiving system 42b, and the projection optical system PL are attached to the same member (first column 32), and the positional relationship between them is maintained constant.

  The irradiation system 42a has a light source that is controlled to be turned on and off by the main controller 50, directs an imaging light beam for forming images of a large number of pinholes or slits toward the imaging surface of the projection optical system, and an optical axis. Irradiate the wafer surface obliquely with respect to AX. On the other hand, the reflected light beam of the imaging light beam reflected on the wafer surface is received by the light receiving element in the light receiving system 42b and converted into an electric signal (defocus signal). The defocus signal (defocus signal) is supplied to the stage controller 20 and the main controller 50 through the stage controller 20.

Further, in the exposure apparatus 100 of the present embodiment, although not shown in FIG. 1, the off-axis alignment system ALG (FIG. 2, FIG. 2) is provided on the −Y side of the projection unit PU of the first column 32. 4). As this alignment system ALG, for example, a broadband detection light beam that does not expose the resist on the wafer is irradiated to the target mark, and an image of the target mark formed on the light receiving surface by the reflected light from the target mark is not shown. An image processing type FIA (Field Image Alignment) type sensor that captures an image of an index using an imaging device (CCD) or the like and outputs an image pickup signal thereof is used. This alignment system ALG supplies mark position information relative to the index center to main controller 50. Based on the supplied information and the measurement value of the interferometer system 18, the main controller 50 detects the mark to be detected, specifically, the second reference mark on the reference mark plate FM described above or the wafer. alignment mark of the alignment coordinate system to measure the position information on (the optical axis of the X-axis interferometer 18X _2, the coordinate system at the time of the foregoing wafer alignment defined by the optical axis of the Y-axis interferometers 18Y) It has become.

  FIG. 4 is a block diagram showing the main configuration of the control system in the exposure apparatus 100 of the present embodiment. In FIG. 4, a control system is configured with the main controller 50 and the stage controller 20 as the center.

  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. The stage control device 20 includes a microcomputer, and in response to an instruction from the main control device 50, the reticle stage drive unit 12, the XY drive unit 29, the Z position drive units 38A to 38C, the first vibration isolation mechanisms 56A to 56C, and The second vibration isolation mechanisms 66A to 66C and the like are controlled.

  Although description has been made before and after, also in the exposure apparatus 100 of the present embodiment, in order to align the AF surface with the upper surface of the wafer table WTB, that is, to make the AF surface and the moving surface (running surface) of the wafer stage WST parallel. The adjustment is performed in the same procedure as described above.

  FIG. 5 is a functional block diagram showing the configuration of a control system related to the position control of wafer table WTB of exposure apparatus 100. The functional block diagram of the stage control device 20 shown in FIG. 5 shows the function at the time of scanning exposure, and the functions realized by various control programs (software) executed by the microprocessor constituting the stage control device 20. Part of it is shown as a block. Of course, hardware corresponding to some of the components shown in the functional block diagram of FIG. 5 may be provided.

  In FIG. 5, the stage controller 20 includes a stage position command generator 20a, a converter 20b, a wafer stage controller 20c, a table position command generator 20d, a calculator 20e, a table controller 20f, and a base position command generator 20g. , A base control unit 20h, a correction unit 20i, and the like. In addition, the stage control device 20 also includes a reticle stage control unit that controls the reticle stage drive unit 12 and drives the reticle stage RST in the scanning direction via the reticle stage drive unit 12 during scanning exposure. In synchronism with this, the wafer stage WST is driven in the opposite direction to the reticle stage RST at a speed ratio corresponding to the projection magnification of the projection optical system PL via the XY drive unit 29. That is, the stage controller 20, the reticle stage drive unit 12, and the XY drive unit 29 constitute a drive system that moves the wafer stage WST in the scanning direction in synchronization with the reticle stage RST (see FIG. 4). However, description of the reticle stage control unit and the like is omitted here.

The stage position command generation unit 20a outputs a position command (X ₀ , Y ₀ , θz ₀ ) for the wafer stage WST to the subsequent subtraction unit P1 in response to an instruction from the main controller 50.

The converter 20b receives the measurement values WX _B , WY _L , WY _R of the interferometer system 18 and inputs these measurement values (WX _B , WY _L , WY _R ) in the X-axis direction of the center of gravity of the wafer stage WST, The position information (X, Y, θz) in the Y-axis direction and θz direction is converted and output to the subtraction unit P1.

The subtractor P1 calculates a position deviation (ΔX, ΔY, Δθz) that is a difference between the position command (X ₀ , Y ₀ , θz ₀ ) and the position information (X, Y, θz), and controls the wafer stage. To the unit 20c.

  The wafer stage control unit 20c performs, for example, (proportional + integral) control operation using the position deviation (ΔX, ΔY, Δθz) as an operation signal, and makes the position deviation (ΔX, ΔY, Δθz) close to zero. A controller that calculates a speed command value in the θz direction and a calculator that calculates a thrust command value for the XY drive unit 29 based on the speed command value from the controller are provided. By driving the XY drive unit 29 based on the thrust command value from the wafer stage control unit 20c, the position (including θz rotation) of the wafer stage WST in the XY plane is controlled.

  The table position command generation unit 20d uses a predetermined value, in this case (0, 0, 0), as a target value for the position of the surface of the wafer W (or the upper surface of the wafer table WTB) in the Z-axis direction, θx direction, and θy direction. ) Is output to the subtraction unit P2 at the subsequent stage.

  Based on the output of the light receiving system 42b of the multi-point AF system, the arithmetic unit 20e is configured to obtain positional information (Z, θx, θy) is calculated and output to the subtraction unit P2.

  The subtraction unit P2 has positional deviations (ΔZ (= −Z), Δθx (= −θx), Δθy (= −) that are differences between the target values (0, 0, 0) and the positional information (Z, θx, θy). θy)) is calculated and output to the table control unit 20f.

In addition to the position deviations (ΔZ, Δθx, Δθy), the table control unit 20f includes measured values (WX _B , WY _L , WY _R ) of the interferometer system 18 and outputs (Z _21A ) from the three encoders 23A-23C. , Z _21B , Z _21C ) are also input. As an example, the table control unit 20f performs, for example, a (proportional + integral) control operation using the position deviation (ΔZ, Δθx, Δθy) as an operation signal so that the position deviation (ΔZ, Δθx, Δθy) approaches zero. A controller that calculates speed command values in the Z, θx, and θy directions, an integrator that integrates the command values from the controller, an output from the integrator, and measured values of the interferometer system 18 (WX _B , WY _L , WY _R ) And a position command output from each of the encoders 23A to 23C (Z _21A , Z _21B , Z _21C ) A subtractor for calculating a position deviation as a difference, and a conversion gain for converting the position deviation output from the subtractor into a command value for each of the actuators 21A to 21C. (Or controller with the conversion gain equivalent function) is configured to include a like. Further, from the table control unit 20f, a position deviation (that is, a difference between the position command for each of the actuators 21A to 21C and the corresponding measurement value of the encoders 23A to 23C) (ΔZ _21A , ΔZ _21B ) which is an output of the subtraction unit therein. , ΔZ _21C ) is output to the correction unit 20 i described later.

  At the time of scanning exposure or the like, the arithmetic unit 20e of the stage control device 20 performs the Z position on the surface of the wafer W based on a defocus signal (defocus signal) such as an S curve signal from the multipoint AF system (42a, 42b). , Θx direction rotation, θy direction rotation (Z, θx, θy) are calculated, and the position deviation (ΔZ, Δθx, Δθy) is calculated by the subtraction unit P2 based on the calculation result. Based on the position deviations (ΔZ, Δθx, Δθy), the table control unit 20f calculates the drive amounts (thrust command values for the actuators) of the actuators 21A to 21C, and is driven by the actuators 21A to 21C. The actuators 21A to 21C are driven while monitoring the outputs of the linear encoders 23A to 23C that detect the displacement of the corresponding support point in the Z-axis direction. In this way, the movement of wafer table WTB in the Z-axis direction and the two-dimensional tilt (that is, rotation in the θx and θy directions) are controlled, and the irradiation region of illumination light IL (conjugated with the illumination region described above) is controlled. The focus / leveling operation of the wafer W is performed so that the surface of the wafer W substantially coincides with the imaging plane of the projection optical system PL within the irradiation area of the illumination light IL.

The base position command generation unit 20g subtracts the servo target values (Z ′ _66A , Z ′ _66B , Z ′ _66C ) of the Z position of the support point of the stage base 71 by the second vibration isolation mechanisms _{66A to 66C in the subsequent} stage. To the part P3. This servo target value will be further described later.

In addition to the servo target values (Z ′ _66A , Z ′ _66B , Z ′ _66C ), the subtraction unit P3 includes displacements of the support points of the second vibration isolation mechanisms _{66A to 66C} from the displacement sensors 64A to 64C (Z _66A , Z _66B , Z _66C ) is input. The adding unit P3 includes position deviations (ΔZ _66A , ΔZ _66B , ΔZ _66C ) that are differences between the servo target values (Z ′ _66A , Z ′ _66B , Z ′ _66C ) and displacements (Z _66A , Z _66B , Z _66C ). ) And the positional deviations (ΔZ _66A , ΔZ _66B , ΔZ _66C ) are output to the base control unit 20h.

The base control unit 20h is configured by a controller or the like that performs, for example, (proportional + integral) control operation using the position deviation (ΔZ _66A , ΔZ _66B , ΔZ _66C ) as an operation signal, and the position deviation (ΔZ _66A , ΔZ _66B , ΔZ _66C). ) Is calculated for the second vibration isolation mechanisms 66A to 66C so as to be close to zero, and is output to the second vibration isolation mechanisms 66A to 66C.

The correction unit 20i calculates correction information (d _66A , d _66B , d _66C ) based on the input of the above-described positional deviations (ΔZ _21A , ΔZ _21B , ΔZ _21C ) from the table control unit 20f, and the base It is output to the position command generator 20g.

  Here, the function of the correction unit 20i will be further described.

  As is clear from the above description, the stage control device 20 and the drive system controlled by the stage control device 20 and the like, the difference in control state caused by the difference in the drive state with respect to the XY stage 28 of the wafer table WTB, for example, for each shot of the running surface When the forward / reverse difference of AF caused by the difference or other control error does not occur, the base position command generation unit 20g matches the surface position of the reference plane plate described above with the AF surface (that is, the AF surface and the wafer stage WST). It is sufficient to output a command value (hereinafter referred to as a basic command value) as a servo target value, which maintains the value when adjustment is performed in advance so that the upper surface of the stage base 71 which is a moving surface (running surface) is parallel. .

  On the other hand, for example, when there is a possibility that a control error such as a forward / reverse difference of AF due to a difference in each shot of the running surface may occur, a command value that corrects this error as a result (basic command value is corrected) It is desirable that the base position command generator 20g outputs the command value as a servo target value.

Therefore, the correction unit 20i sends the difference between the position command sent from the table control unit 20f to the actuators 21A to 21C and the corresponding measurement values of the encoders 23A to 23C, that is, the above-described position deviations (ΔZ _21A , ΔZ _21B , ΔZ _21C ), the driving state of the wafer table WTB with respect to the XY stage 28 (the driving state of the actuators 21A to 21C) is obtained, and correction information (d _66A) for the second vibration isolation mechanisms _{66A to} 66C according to this driving state. , D _66B , d _66C ) in consideration of the measurement value of the interferometer system 18, and the correction information (d _66A , d _66B , d _66C ) is output to the base position command generator 20g.

More specifically, in the focus / leveling operation of the wafer W, the exposure area (projection area of the illumination light IL by the projection optical system conjugate to the illumination area IAR) on the wafer W coincides with the image plane. Such Z position and tilt control of the wafer table WTB is performed based on the measurement result of the multipoint AF system (42a, 42b). At this time, when the actuators 21A to 21C are not driven according to the command values, errors with respect to the command values are detected via the encoders 23A to 23C, and position deviations (ΔZ _21A , ΔZ _21B , ΔZ _21C ) corresponding to the errors are detected. Correction from the table control unit 20f to the correction unit 20i is corrected by the correction unit 20i with respect to the second vibration isolation mechanisms 66A to 66C for canceling the error in consideration of the measurement value of the interferometer system 18 at that time. Information (d _66A , d _66B , d _66C ) is obtained, and the correction information (d _66A , d _66B , d _66C ) is supplied to the base position command generation unit 20g.

The base position command generating unit 20g is subtracted basic command value correction information _{(d 66A, d 66B, d} 66C) command value corrected by _{(Z '66A, Z' 66B} , Z '66C) as a servo target value To the part P3. The subtraction unit P3 is a position deviation (ΔZ) that is a difference between the servo target values (Z ′ _66A , Z ′ _66B , Z ′ _66C ) and the measured values (Z _66A , Z _66B , Z _66C ) of the displacement sensors 64A to 64C. _66A , ΔZ _66B , ΔZ _66C ) are output to the base controller 20h. Then, using the position deviations (ΔZ _66A , ΔZ _66B , ΔZ _66C ) as operation signals, the base control unit 20 h performs a control operation so that the aforementioned position deviations (ΔZ _21A , ΔZ _21B , ΔZ _21C ) approach zero. The positions of the stage base 71 in the Z, θx, and θy directions are adjusted via the second vibration isolation mechanisms 66A to 66C.

  In this way, the focus / leveling operation of the wafer W is continued without any trouble.

Here, as one of the factors that cause the actuators 21 </ b> A to 21 </ b> C not to be driven according to the command value, the upper surface of the stage base 71 that is the moving surface (running surface) of the wafer stage WST, which causes the above-described AF forward / reverse difference. A phenomenon in which the wafer stage WST is tilted with respect to the above-described AF plane (which substantially coincides with the image plane of the projection optical system PL) as the wafer stage WST moves is mentioned. When a phenomenon occurs in which the actuators 21A to 21C are not driven according to the command value due to the inclination of the position of the interferometer system 18, correction information for making the positional deviations (ΔZ _21A , ΔZ _21B , ΔZ _21C ) close to zero at this time It is calculated by the correction unit 20i in consideration of the measured value, and the base control unit 20h performs the stage base through the second vibration isolation mechanisms 66A to 66C according to the correction information. 71 Z, [theta] x, the θy direction position is adjusted.

  Here, the correction information described above corresponds to the inclination state of the upper surface of the stage base 71 with respect to the AF surface (which is substantially coincident with the image plane of the projection optical system PL) according to the movement state of the wafer stage WST in the XY plane. Correction information. Therefore, in this embodiment, the forward / reverse difference of AF (the difference in focus control according to the scan direction depending on whether the shot area is subjected to plus scanning or the shot area where minus scanning is performed) is also suppressed.

  Next, the operation of the exposure process executed by the exposure apparatus 100 of the present embodiment will be briefly described.

  In the exposure apparatus 100, similarly to a normal scanning stepper, after performing preparatory work such as reticle alignment, baseline measurement, and wafer alignment (such as EGA method), scanning exposure on a shot area on the wafer W, Step-and-scan exposure is performed in which wafer movement between shot areas is alternately repeated. Since the operation of this exposure process is basically the same as that of a normal scanning stepper, detailed description thereof is omitted.

  In FIG. 6, as an example, when a plurality of (for example, 76) shot areas are exposed, irradiation of the illumination light IL conjugate with the above-described illumination area IAR during the step-and-scan is performed on the wafer. The locus of relative movement on the wafer W of the center point (substantially coincident with the optical axis AX) of the area, that is, the exposure area IA shown in FIG. 2 is shown. The solid line portion in the trajectory of FIG. 6 indicates the path of the center point of the exposure area IA at the time of exposure of each shot area, and the dotted line portion indicates the exposure area IA between adjacent shot areas in the same row in the non-scanning direction. The movement locus of the center point is shown, and the one-dot chain line portion shows the movement locus of the center point of the exposure area IA between different rows. Actually, the exposure area IA is fixed and the wafer W moves. However, in FIG. 6, for convenience of explanation, it is illustrated as if the center point of the exposure area IA moves on the wafer W. Yes.

In this case, the movement of the wafer W between different shot areas is performed without stopping. That is, the wafer W is moved so that at least one velocity component in the scanning direction and the non-scanning direction does not become zero until the scanning exposure from the first shot S ₁ to the last shot S ₇₆ is completed. Therefore, movement operation between shot areas of wafer stage WST can be performed in a short time, and throughput can be improved.

During the scanning exposure described above, the focus leveling operation of the wafer W described above, and the accompanying correction information based on the output signals (Z _21A , Z _21B , Z _21C ) from the encoders 23A to 23C by the stage control device 20 are accompanied. The calculation and control of the second vibration isolation mechanisms 66A to 66C according to the correction information are executed.

  As described above, according to the exposure apparatus 100 of the present embodiment, the stage controller 20 performs the scanning exposure for transferring the pattern formed on the reticle R onto the wafer W via the projection optical system PL. In order to maintain a predetermined positional relationship between the wafer W and the reference plane (the above-described AF plane (adjusted so as to substantially match the image plane of the projection optical system PL)), the Z position driving units 38A to 38C are respectively set. The XY stage 28 (wafer stage WST) is driven while driving the wafer table WTB in at least one direction of the optical axis direction of the projection optical system PL and the inclination direction with respect to the plane orthogonal to the optical axis via the actuators 21A to 21C. Moved. Further, the stage controller 20 acquires the detection values of the encoders 23A to 23C for detecting the driving amount of the wafer table WTB with respect to the XY stage 28 by the actuators 21A to 21C while the XY stage 28 (wafer stage WST) is moving. Based on the acquired detection values of the encoders 23A to 23C (that is, the driving amount of the wafer table WTB with respect to the XY stage 28), the wafer W in at least one of the Z-axis (optical axis AX) direction and the tilt direction with respect to the XY plane. Is controlled.

  In this case, the stage control device 20 can know the driving state of the wafer table WTB with respect to the XY stage 28 based on the position command for the actuators 21A to 21C and the detection values of the encoders 23A to 23C, and according to the driving state. Correction information is calculated based on the control state, and the second vibration isolation mechanisms 66A to 66C are controlled based on the correction information, and the position of the wafer W in at least one of the optical axis AX direction and the tilt direction with respect to the XY plane is determined. By controlling, a predetermined positional relationship between the wafer W and the reference plane is maintained.

  Therefore, the stage controller 20 performs the above-described control with the above-described reference plane as the best imaging plane (image plane) of the pattern by the projection optical system PL or an AF plane substantially matching this, so that the wafer table WTB It becomes possible to realize the transfer of the pattern onto the wafer W without being affected by the difference in the control state caused by the difference in the driving state with respect to the XY stage 28. In the present embodiment, it is possible to realize the focus leveling control of the wafer W that is not affected by the difference in the driving state of the wafer table WTB with respect to the XY stage 28, so that the pattern transfer accuracy is adversely affected. AF forward / reverse difference does not occur.

  Further, as in this embodiment, when the wafer W (wafer stage WST) is continuously moved not only during scanning exposure but also during stepping between shots, a focus follow-up operation performed during stepping between shots is performed. Among them, it is possible to effectively prevent the occurrence of a control error in the Z-axis direction of the wafer W, which is the same as the forward / reverse difference of AF generated according to the direction of movement of the wafer.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIG. The exposure apparatus according to the second embodiment differs from the exposure apparatus 100 of the first embodiment described above in part of the function of the stage control apparatus (that is, the functional block diagram of the stage control apparatus). The structure and operation of the parts are the same. Therefore, in the following, the above differences will be mainly described from the viewpoint of avoiding repeated explanation. From the same point of view, the same reference numerals are used for the same or equivalent components as in the first embodiment, and the description thereof is omitted.

  FIG. 7 is a functional block diagram showing a configuration of a control system related to position control of wafer table WTB of the exposure apparatus according to the second embodiment. The functional block diagram of the stage control device 20 ′ shown in FIG. 7 shows the one during scanning exposure, and is realized by various control programs (software) executed by the microprocessor constituting the stage control device 20 ′. A part of the function is shown in a block form. Of course, hardware corresponding to some of the components shown in the functional block diagram of FIG. 7 may be provided.

  In FIG. 7, a stage control device 20 ′ includes a stage position command generation unit 20a, a conversion unit 20b, a wafer stage control unit 20c, a table position command generation unit 20d, a calculation unit 20e, a table control unit 20f, a correction unit 20j, and the like. I have. In addition, the stage control device 20 ′ includes a reticle stage control unit that controls the reticle stage drive unit 12, a control system (base position command generation unit, base control unit, etc.) of the second vibration isolation mechanisms 66A to 66C, and the like. Although they are provided, illustrations thereof are omitted here.

  As is apparent from a comparison between the functional block diagram of FIG. 7 and the functional block diagram of FIG. 5, in the second embodiment, the above-described correction unit that has output the correction information to the base position command generation unit. Instead of 20i, a correction unit 20j that outputs correction information to the control system of the actuators 21A to 21C is provided, which is different from the first embodiment.

The correction unit 20j performs a predetermined calculation (including coordinate conversion calculation) on the basis of the input of the above-described positional deviations (ΔZ _21A , ΔZ _21B , ΔZ _21C ) from the table control unit 20f, and performs correction information (Z ′, θx ′, θy ′) is calculated and output to the addition unit P4 provided between the table position command generation unit 20d and the subtraction unit P2. As a result, the addition value (Z ′, θx ′,...) Of the correction information (Z ′, θx ′, θy ′) from the correction unit 20j and the position command (0, 0, 0) from the table position command generation unit 20d. θy ′), that is, correction information (Z ′, θx ′, θy ′) is output from the addition unit P4 to the subtraction unit P2 as a substantial target value. As described above, in the second embodiment, the correction information is given as the position command (0, 0, 0) from the table position command generation unit 20d, that is, as an offset with respect to the target position of the wafer table WTB. Then, the subtraction unit P2 obtains a position deviation (ΔZ (= Z′−) that is a difference between the correction information (Z ′, θx ′, θy ′) and the position information (Z, θx, θy) obtained by the calculation unit 20e. Z), Δθx (= θx′−θx), Δθy (= θy′−θy)) are calculated and output to the table control unit 20f.

  As a result, the table control unit 20f uses the position deviations (ΔZ, Δθx, Δθy) as operation signals to control the actuators 21A to 21C so that the position deviations (ΔZ, Δθx, Δθy) approach zero. This is performed in the same manner as in the first embodiment.

Here, during the focus / leveling operation of the wafer W, the Z position and tilt control of the wafer table WTB such that the exposure area IA on the wafer W coincides with the image plane is controlled by the multipoint AF system (42a, 42b). This is performed based on the measurement result. At this time, when the actuators 21A to 21C are not driven according to the command values, errors with respect to the command values are detected via the encoders 23A to 23C, and position deviations (ΔZ _21A , ΔZ _21B , ΔZ _21C ) corresponding to the errors are detected. Input from the table control unit 20f to the correction unit 20j, and the correction unit 20j performs a calculation including a predetermined coordinate transformation calculation, and correction information (Z ′, θx ′, θy ′) is obtained, and the correction information (Z ′, θx ′, θy ′) is output to the adding unit P4. As described above, the correction information (Z ′, θx ′, θy ′) is output as a substantial target value from the addition unit P4 to the subtraction unit P2, and the target value and the position obtained by the calculation unit 20e are output. The actuators 21A to 21C are driven by the table control unit 20f using the position deviation, which is the difference from the information (Z, θx, θy) as an operation signal.

Although not shown in the second embodiment, the base position command generation unit 20g outputs the basic command values described above to the subtraction unit P3 as servo target values Z ′ _66A , Z ′ _66B , Z ′ _66C. To do. The second vibration isolation mechanisms 66A to 66C are driven via the base control unit 20h according to the servo target value.

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

  According to the exposure apparatus according to the second embodiment configured as described above, it is possible to obtain the same effects as those of the first embodiment described above, and based on the correction information, the second vibration isolation mechanism 66A. Since the actuators 21A to 21C, which are more responsive than the 66C (stage base 71), are driven, the control error of the wafer or the like caused by the difference in the driving state of the wafer table WTB with respect to the XY stage 28 such as the AF forward / reverse difference is more reliably detected Occurrence can be suppressed.

  It should be noted that the functional block diagrams of the stage control devices 20 and 20 'described in the first and second embodiments are merely examples, and the present invention is of course not limited thereto. For example, in the first embodiment, the outputs of the encoders 23A to 23C and the output of the table control unit 20f are directly input to the correction unit 20i, and the correction unit 20i drives the actuators 21A to 21C based on those outputs. The state may be estimated, and the correction information may be calculated based on the estimated driving state and the measurement value of the interferometer system. Alternatively, even if the same configuration as in the first embodiment is adopted, for example, the internal configuration of the table control unit 20f may be changed. For example, after the outputs of the encoders 23A to 23C are input into the table control unit 20f, the output is differentiated and coordinate-converted, and the speed information after the coordinate conversion and the speed command regarding the Z, θx, and θy directions output from the controller. The deviation from the value may be calculated. In this case, a controller that calculates an acceleration command value using the deviation (speed deviation) as an operation signal, and an output of the controller is converted into a command value for the actuators 21A to 21C in consideration of the measurement value of the interferometer system 18. It is necessary to provide a part for performing the operation to be performed. As described above, various internal configurations of the stage control devices 20 and 20 ′ are conceivable. In short, the operation states of the actuators 21A to 21C are recognized based on the measurement values of the encoders 23A to 23C, and the operation states are changed to these operation states. By controlling at least one of the actuators 21A to 21C and the second vibration isolation mechanisms 66A to 66C using the corresponding correction information, the optical axis AX direction (Z axis direction) and the XY plane of the wafer W (wafer table WTB) As long as position control is performed in at least one direction of the inclination direction (θx direction, θy direction) with respect to.

  In each of the above embodiments, the case where the present invention is applied to a scanning exposure apparatus such as a step-and-scan method has been described. However, the present invention is not limited to this, and step-and-stitch is used. The present invention can also be applied to an exposure apparatus of a system type or an exposure apparatus of a proximity system.

  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.

In each of the embodiments described above, the case where the exposure apparatus 100 uses ArF excimer laser light as the illumination light IL has been described. However, the present invention is not limited thereto, and KrF excimer laser light (wavelength 248 nm) is, of course, from an ultrahigh pressure mercury lamp. Other ultraviolet ultraviolet light (for example, g-line, i-line, etc.), light having a wavelength of 170 nm or less, such as F ₂ laser light (wavelength 157 nm), Kr ₂ laser light (wavelength 146 nm), etc. May be.

  Further, for example, not only laser light output from each of the above light sources as vacuum ultraviolet light, but also single wavelength laser light in the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser, for example, erbium (Er) A harmonic that is amplified by a fiber amplifier doped with erbium and ytterbium (Yb) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

  In the exposure apparatus of the present invention, it is needless to say that the illumination light is not limited to light having a wavelength of 100 nm or more, and light having a wavelength of less than 100 nm may be used. For example, in recent years, in order to expose a pattern of 70 nm or less, EUV (Extreme Ultraviolet) light in a soft X-ray region (for example, a wavelength region of 5 to 15 nm) is generated using an SOR or a plasma laser as a light source, and its exposure wavelength Development of an EUV exposure apparatus using an all-reflection reduction optical system designed under (for example, 13.5 nm) and a reflective mask is underway. In this apparatus, a configuration in which scanning exposure is performed by synchronously scanning the mask and the wafer using arc illumination is conceivable, so that the present invention can also be suitably applied to such an apparatus. Further, for example, an immersion type exposure apparatus disclosed in International Publication WO99 / 49504, etc., in which a liquid (for example, pure water) is filled between the projection optical system and the wafer, or a step-and-stitch method. The present invention can also be suitably applied to an exposure apparatus or a proximity type exposure apparatus. Furthermore, the present invention can be suitably applied not only to ultraviolet light as illumination light IL but also to an exposure apparatus, an X-ray exposure apparatus, and the like that use a charged particle beam such as an electron beam or an ion beam.

  The present invention is not limited to an exposure apparatus for manufacturing a semiconductor, but is used for manufacturing a display including a liquid crystal display element. An exposure apparatus for transferring a device pattern onto a glass plate and a device used for manufacturing a thin film magnetic head. The present invention can also be applied to an exposure apparatus that transfers a pattern onto a ceramic wafer, and an exposure apparatus that is used for manufacturing an imaging device (CCD or the like), micromachine, organic EL, DNA chip, and 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.

  The semiconductor device is formed on the mask by 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 the exposure apparatus of each of the above embodiments. It is manufactured through a lithography step for transferring the pattern onto the photosensitive object, 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 exposure apparatus of the present invention is suitable for manufacturing micro devices such as semiconductor elements and liquid crystal display elements.

It is a figure which shows schematically the structure of the exposure apparatus of 1st Embodiment. It is a top view which shows a wafer stage and an interferometer system. FIG. 2 is a partial cross-sectional view of a component near one end of the stage base of FIG. 1. FIG. 2 is a block diagram showing a main part of a control system of the exposure apparatus in FIG. 1. It is a functional block diagram which shows the structure of the control system relevant to the position control of the wafer table in the exposure apparatus of 1st Embodiment. It is a figure which shows schematically the movement locus | trajectory of the center point of the exposure area | region at the time of performing the exposure with respect to several shot area | regions on the wafer W with the exposure apparatus of 1st Embodiment. It is a functional block diagram which shows the structure of the control system relevant to the position control of the wafer table in the exposure apparatus of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 ... Reticle stage drive part (a part of synchronous drive system), 20 ... Stage control apparatus (control apparatus), 21A-21C ... Actuator (drive mechanism), 23A-23C ... Encoder (sensor), 29 ... XY drive part ( 60a... Light receiving system (part of multipoint focal position detection system), 60b... Irradiation system (part of multipoint focal position detection system), 66A to 66C. (Drive device), 71 ... stage base (surface plate), 100 ... exposure apparatus, R ... reticle (mask), PL ... projection optical system, W ... wafer (object), WST ... wafer stage (stage), WTB ... wafer table (Table), RST ... reticle stage (mask stage).

Claims (5)

An exposure apparatus for transferring a pattern formed on a mask onto an object via a projection optical system,
A stage that moves in a plane perpendicular to the optical axis of the projection optical system;
A table on which the object is placed;
A driving mechanism capable of driving the table in the direction of the optical axis of the projection optical system and the direction of inclination with respect to a plane orthogonal to the optical axis on the stage;
A sensor for detecting a driving amount of the table with respect to the stage by the driving mechanism;
In order to maintain a predetermined positional relationship between the object and a reference plane, the stage is moved while the table is driven in at least one of the optical axis direction and the tilt direction via the drive mechanism, and the table is being moved. An exposure apparatus that acquires a detection value of the sensor and controls a position of the object in at least one of the optical axis direction and the tilt direction based on the acquired detection value of the sensor. A surface plate on which the moving surface of the stage is formed;
A driving device capable of driving the surface plate in an optical axis direction of the projection optical system and an inclination direction with respect to a plane orthogonal to the optical axis;
2. The control device according to claim 1, wherein the control device performs position control of at least one of the optical axis direction and the tilt direction of the object by controlling at least one of the driving mechanism and the driving device. The exposure apparatus described. A multi-point focal position detection system that detects position information of the object surface in the optical axis direction at a plurality of detection points in the field of view of the projection optical system;
The reference plane is a plane defined by a detection origin of a light receiving element that detects the position information at each detection point of the multipoint focal position detection system, and a predetermined positional relationship is defined between the reference plane and the object surface. The exposure apparatus according to claim 1, wherein the relationship is substantially coincident.   The control device controls the position of the table by controlling the drive mechanism based on the output of the multipoint focal position detection system, and calculates correction information based on the acquired detection value of the sensor. 4. The exposure apparatus according to claim 3, wherein the correction information is an offset with respect to a target position of the table. A mask stage on which the mask is placed;
An exposure apparatus according to claim 1, further comprising: a drive system that moves the stage in a predetermined direction in synchronization with the mask stage.

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