JP5861858B2 - Exposure method, exposure apparatus, and device manufacturing method - Google Patents

Description

  The present invention relates to an exposure method, an exposure apparatus, and a device manufacturing method, and more particularly, an exposure method and an exposure apparatus used in a lithography process for manufacturing a microdevice such as a semiconductor element, and a device manufacturing using the exposure method. Regarding the method.

  In lithography processes for manufacturing electronic devices (microdevices) such as semiconductor elements (integrated circuits, etc.) and liquid crystal display elements, step-and-repeat exposure apparatuses (so-called steppers) and step-and-scan exposures are mainly used. An apparatus (a so-called scanning stepper (also called a scanner)) or the like is used.

  In this type of exposure apparatus, a high overlay accuracy (positioning accuracy) has been required with the miniaturization of device patterns due to high integration of semiconductor elements. Therefore, higher accuracy has been required for position measurement of a wafer or the like (substrate) on which a pattern is formed.

  As an apparatus that meets such demands, for example, Patent Document 1 proposes an exposure apparatus that includes a position measurement system that uses a plurality of encoder type sensors (encoder heads) mounted on a substrate table. In this exposure apparatus, the encoder head measures the position of the substrate table by irradiating the scale disposed opposite to the substrate table with the measurement beam and receiving the return beam from the scale. The scale is composed of a plurality of portions facing each of the plurality of encoder heads, and covers the movement area of the substrate table excluding the area directly under the projection optical system.

  The exposure apparatus is also required to have high throughput. A twin stage type exposure apparatus provided with a plurality of, for example, two substrate stages is known as a device that can meet such a demand. In this type of exposure apparatus, throughput is improved by performing different operations, for example, an exposure operation and an alignment operation in parallel on two substrate stages. In a twin stage type exposure apparatus, a planar motor is employed as a drive source in order to ensure the maximum degree of freedom of movement of each substrate stage (see, for example, Patent Document 2).

  However, recently, in a twin stage type exposure apparatus, the measurement value of a position measurement system (such as an encoder) that measures the position of the other substrate stage is very small as the one substrate stage moves. Turned out to receive. In the era when device rules in the future become finer than 32 nm, such position measurement errors cannot be ignored.

US Patent Application Publication No. 2006/0227309 US Pat. No. 6,437,463

  The inventor conducted intensive research to find out the main cause of the above-described position measurement error, and as a result, it was found that the magnetic field fluctuation (change) in the apparatus due to the change in the position of the substrate stage was the main factor. The present invention has been made under such circumstances.

According to the first aspect of the present invention, there is provided an exposure method in which an object is exposed with an energy beam to form a pattern on the object, and individually by a planar motor on a surface plate having a guide surface parallel to a predetermined plane. first, second positional information about the first position information and the second movable body related to the first mobile body obtained I by the pair to position measurement system to each of the second movable body that is driven When the first of the first movable body is driven for holding the pre-Symbol object based on the first correction information obtained prior to the driving of the movable body, the first correction information, the second moving member There is provided an exposure method obtained from a measurement error of the position measurement system included in the first position information, which occurs according to the position in the predetermined plane .

  According to this, it is possible to correct a measurement error according to the position of the second moving body included in the first position information of the first moving body measured by the position measurement system, and as a result, the first moving body It becomes possible to drive with high accuracy.

  According to a second aspect of the present invention, there is provided a device manufacturing method comprising: forming a pattern on an object using the exposure method of the present invention; and developing the object on which the pattern is formed. Provided.

According to a third aspect of the present invention, there is provided an exposure apparatus that exposes an object with an energy beam to form a pattern on the object, the surface plate having a guide surface parallel to a predetermined plane; A planar motor including a stator provided on the first and second movable elements facing the guide surface, and the first and second movable elements. First and second moving bodies driven along a guide surface, a position measuring system for measuring the positions of the first and second moving bodies, and a position of the first moving body from the position measuring system The first movement for holding the object based on information, position information of the second moving body from the position measurement system, and first correction information obtained prior to driving of the first moving body driving the body, the first correction information, prior to the second moving member Occur depending on the position within the predetermined plane, wherein a driving device obtained from the measurement error of the position measurement system in which the first included in the position information, an exposure apparatus equipped with is provided.

  According to this, the position information of the first moving body from the position measuring system, the position information of the second moving body from the position measuring system, and the first correction information corresponding to the position of the second moving body are driven by the driving device. Based on the above, the first moving body that holds the object is driven. Here, the first correction information is information for correcting a measurement error corresponding to the position of the second moving body included in the position information of the first moving body measured by the position measurement system. Therefore, the first moving body can be driven with high accuracy.

It is a figure which shows schematically the structure of the exposure apparatus which concerns on one Embodiment. It is a figure which shows the structure of the encoder system arrange | positioned around a projection optical system. It is a figure which shows the structure of the encoder system arrange | positioned around an alignment system. FIG. 3 is an enlarged view showing a partially broken wafer stage. It is a figure which shows arrangement | positioning of the encoder head on a wafer stage. FIG. 2 is a block diagram showing a main configuration of a control system related to stage control in the exposure apparatus of FIG. 1. 7A and 7B are diagrams showing the magnetic field around the stage apparatus of the exposure apparatus of FIG. FIG. 8A is a diagram showing aerial image measurement slits provided on the wafer table, FIG. 8B is a diagram showing measurement marks provided on the reticle stage, and FIG. It is a figure for demonstrating the scanning of the slit for aerial image measurement with respect to the projection image of a mark.

  Hereinafter, an 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. The exposure apparatus 100 is a step-and-scan projection exposure apparatus, that is, a so-called scanner. As will be described later, in the present embodiment, a projection optical system PL is provided. In the following description, a reticle and wafer are arranged in a direction perpendicular to the Z-axis direction parallel to the optical axis AX of the projection optical system PL and in a plane perpendicular to the Z-axis direction. And the direction perpendicular to the Z axis and the Y axis are the X axis directions, and the rotation (tilt) directions around the X axis, the Y axis, and the Z axis are θx, θy, and The description will be made with the θz direction.

  The exposure apparatus 100 includes an illumination system 10, a reticle stage RST for holding the reticle R, a projection unit PU, a wafer stage device 50 including wafer stages WST1 and WST2 on which the wafer W is placed, a control system for these, and the like. Yes.

  The illumination system 10 includes a light source, an illuminance uniformizing optical system including an optical integrator, a reticle blind, and the like (both not shown) as disclosed in, for example, US Patent Application Publication No. 2003/0025890. And an illumination optical system. The illumination system 10 illuminates the slit-shaped illumination area IAR on the reticle R defined by the reticle blind (masking system) with illumination light (exposure light) IL with a substantially uniform illuminance. Here, as the illumination light IL, for example, ArF excimer laser light (wavelength 193 nm) is used.

  On reticle stage RST, reticle R on which a circuit pattern or the like is formed on its pattern surface (the lower surface in FIG. 1) is fixed, for example, by vacuum suction. The reticle stage RST is provided with a later-described reticle mark plate. The reticle stage RST can be finely driven in the XY plane by a reticle stage drive system 11 (not shown in FIG. 1, refer to FIG. 6) including a linear motor, for example, and in the scanning direction (in the direction orthogonal to the paper surface in FIG. 1). It can be driven at a predetermined scanning speed in a certain Y-axis direction.

  Position information (including information on the position in the θz direction (θz rotation amount)) in the XY plane (moving plane) of reticle stage RST is shown in FIG. 1 as moving mirror 15 (actually perpendicular to the Y-axis direction). A reticle laser interferometer (hereinafter referred to as “a movable mirror having a reflecting surface that is provided with an X moving mirror having a reflecting surface orthogonal to the X-axis direction”). For example, it is always detected with a resolution of about 0.25 nm. In order to measure the position information of the reticle R in the direction of at least three degrees of freedom, it is disclosed in, for example, US Patent Application Publication No. 2007/0288121 instead of or in combination with the reticle interferometer 16. An encoder system may be used.

  Projection unit PU is arranged below reticle stage RST in FIG. 1 (on the −Z side), and is held by a main frame (metrology frame) that forms part of a body (not shown). The projection unit PU has a lens barrel 40 and a projection optical system PL composed of a plurality of optical elements held by the lens barrel 40. As the projection optical system PL, for example, a refractive optical system including a plurality of optical elements (lens elements) arranged along an optical axis AX parallel to the Z-axis direction is used. The projection optical system PL is, for example, both-side telecentric and has a predetermined projection magnification (for example, 1/4 times, 1/5 times, or 1/8 times). For this reason, when the illumination area IAR is illuminated by the illumination light IL from the illumination system 10, the illumination that has passed through the reticle R, in which the first surface (object surface) of the projection optical system PL and the pattern surface are substantially aligned, is passed. Due to the light IL, a reduced image of the circuit pattern of the reticle R in the illumination area IAR (a reduced image of a part of the circuit pattern) passes through the projection optical system PL on the second surface (image surface) side of the projection optical system PL. Are formed in an area (exposure area) IA conjugated to the illumination area IAR on the wafer W having a resist (sensitive agent) coated on the surface thereof. The reticle R is moved relative to the illumination area IAR (illumination light IL) in the scanning direction (Y-axis direction) and the exposure area IA (illumination light) by synchronously driving the reticle stage RST and the wafer stages WST1 and WST2. IL) relative to the wafer W in the scanning direction (Y-axis direction), scanning exposure of one shot area (partition area) on the wafer W is performed, and the pattern of the reticle R is formed in the shot area. Transcribed. That is, in the present embodiment, the pattern of the reticle R is generated on the wafer W by the illumination system 10 and the projection optical system PL, and the sensitive layer (resist layer) on the wafer W is exposed on the wafer W by the illumination light IL. A pattern is formed.

  The main frame may be any of a conventionally used portal type and a suspension support type disclosed in, for example, US Patent Application Publication No. 2008/0068568.

  Around the −Z side end of the lens barrel 40, for example, a scale plate 21 is arranged in parallel with the XY plane at a height that is substantially flush with the lower end surface of the lens barrel 40. As shown in FIG. 2, a rectangular or square opening 21 a is formed in the center of the scale plate 21, and the −Z side end of the lens barrel 40 is disposed inside the opening 21 a. The widths of the scale plate 21 in the X-axis direction and the Y-axis direction are A and B, respectively. In this case, A and B may be the same. That is, the scale plate 21 may be square. Further, the opening 21a is not limited to a rectangle or a square, but may be a circle as long as the lower end of the barrel 40 of the projection unit PU can be disposed therein.

  The scale plate 21 is fixed (or suspended) to the lower surface (surface on the −Z side) of the main frame (metrology frame) that supports the projection unit PU, the alignment system ALG, and the like.

  As shown in FIG. 1, the scale plate 22 is fixed (or suspended) on the lower surface (the surface on the −Z side) of the main frame (metrology frame) at a position spaced a predetermined distance in the + X direction from the scale plate 21. Support). As shown in FIG. 3, the scale plate 22 is configured in the same manner as the scale plate 21, and the -Z side end of the alignment system ALG is inserted into the center of the opening 22a (see FIG. 3). 1). Here, the scale plate 22 is not necessarily configured similarly to the scale plate 21. For example, the opening 22a may be different in shape and / or size from the opening 21a. In short, it is only necessary that the opening 22a can be inserted into the −Z side end of the alignment system ALG. 1 and the like, a part of the main frame (metrology frame) 23 to which the scale plates 21 and 22 are fixed is shown.

  On the lower surfaces of the scale plates 21 and 22 (the surface on the -Z side), as a two-dimensional grating, a predetermined pitch with a 45-degree direction based on the X-axis (-45-degree direction based on the Y-axis) as a periodic direction A reflective two-dimensional grating comprising, for example, a 1 μm grating and a predetermined pitch, for example, a 1 μm grating, having a periodic direction in a −45 degree direction with respect to the X axis (−135 degree direction with respect to the Y axis). An RG (see FIGS. 2, 3 and 4) is formed. The two-dimensional gratings RG of the scale plates 21 and 22 cover the moving ranges of the wafer stages WST1 and WST2 during the exposure operation and alignment (measurement), respectively. Here, the two-dimensional grating RG is not necessarily required to have the above two directions as the periodic direction, but may be any biaxial direction in the XY plane. Accordingly, the periodic direction may be, for example, the X-axis direction or the Y-axis direction.

  Wafer stage apparatus 50 includes a stage base 12 supported substantially horizontally on a floor surface by a plurality of (for example, three or four) vibration isolation mechanisms (not shown), and wafer stage WST1 disposed on stage base 12. , WST2, a wafer stage drive system 27 for driving the wafer stages WST1, WST2 (only part of which is shown in FIG. 1, see FIG. 6), a measurement system for measuring the positions of the wafer stages WST1, WST2, and the like. The measurement system includes encoder systems 70 and 71, a wafer laser interferometer system (hereinafter abbreviated as a wafer interferometer system) 18 and the like shown in FIG. The encoder systems 70 and 71 and the wafer interferometer system 18 will be further described later.

  The stage base 12 is made of a member having a flat outer shape, and the upper surface thereof is finished with a very high flatness and serves as a guide surface when the wafer stages WST1 and WST2 are moved. Inside the stage base 12 is accommodated a magnet unit 14a composed of a plurality of magnets arranged two-dimensionally in the XY plane.

  As shown in FIG. 1, wafer stage WST1 is arranged above stage main body 91 and stage main body 91, and stage main body 91 by Z / tilt drive mechanism 28 (not shown in FIG. 1, refer to FIG. 6). The wafer table WTB1 is supported in a non-contact manner. The Z / tilt driving mechanism 28 can be constituted by, for example, three voice coil motors that respectively support the wafer table WTB1 and independently drive in the Z-axis direction at each supporting point. In this case, wafer table WTB1 adjusts the balance between upward force (repulsive force) such as electromagnetic force and downward force (gravity) including its own weight by Z / tilt drive mechanism 28 at three points. In addition to being supported by contact, it is micro-driven in three degrees of freedom in the Z-axis direction, θx direction, and θy direction. A slider portion 91 a is provided at the bottom of the stage main body 91. The slider portion 91a includes a coil unit (not shown) including a plurality of coils arranged in a matrix with the XY two-dimensional direction as the row direction and the column direction, a housing for housing the coil unit, and a bottom surface of the housing And a plurality of air bearings provided around. The coil unit, together with the above-described magnet unit 14a, constitutes a flat motor 30 driven by Lorentz electromagnetic force disclosed in, for example, US Pat. No. 6,437,463 and US Pat. No. 4,654,571. doing.

  Wafer stage WST1 is levitated and supported on stage base 12 by a plurality of air bearings through a predetermined clearance, for example, a clearance of about several μm, and is driven by planar motor 30 in the X-axis direction, Y-axis direction, and θz direction. Is done. Accordingly, the wafer table WTB1 (wafer W) is in a 6-degree-of-freedom direction (X-axis direction, Y-axis direction, Z-axis direction, θx direction, θy direction, and θz direction (hereinafter, X, Y, Abbreviated as Z, θx, θy, θz).

  In the present embodiment, the main controller 20 controls the magnitude and direction of current supplied to each coil (not shown) constituting the coil unit. As shown in FIG. 6, a wafer stage drive system 27 is configured including the planar motor 30 and the aforementioned Z / tilt drive mechanism 28. Further, for example, by using a planar motor (magnetic levitation type planar motor) that generates a force in the Z direction as well as the XY direction disclosed in US Pat. No. 6,437,463, wafer stage WST1. May be driven in the direction of six degrees of freedom. Wafer table WTB1 may be finely movable in at least one of the X-axis direction, the Y-axis direction, and the θz direction.

  On wafer table WTB1, wafer W is placed via a wafer holder (not shown), and, for example, vacuum chucked (or electrostatic chucked) is fixed by a chuck mechanism (not shown). Further, in the vicinity of one corner on wafer table WTB1, a reference mark M is arranged at the center, and a pair of aerial image measurement slit plates SL is arranged on both sides of the reference mark in the X-axis direction. FM is fixed. The surface of the reference mark plate FM is set substantially flush with the surface of the wafer W. As shown in FIG. 8A, the aerial image measurement slit plate SL has an opening pattern (X slit) SLX having a predetermined width (for example, 0.2 μm) whose longitudinal direction is the Y-axis direction, and an X-axis. An opening pattern (Y slit) SLY having a predetermined width (for example, 0.2 μm) whose direction is the longitudinal direction is formed.

  Inside wafer table WTB1, corresponding to the pair of aerial image measurement slit plates SL, an optical system including a condensing lens and a light receiving element (for example, a photomultiplier tube (PMT: photomultiplier tube)) ) Is arranged. Then, a pair of aerial image measuring devices similar to those disclosed in, for example, US Patent Application Publication No. 2002/0041377, etc., by a pair of aerial image measuring slit plates SL and corresponding optical systems and light receiving elements. 45A and 45B (see FIG. 6) are configured. The measurement results (output signals of the light receiving elements) of the aerial image measurement devices 45A and 45B are subjected to predetermined signal processing by a signal processing device (not shown) and sent to the main control device 20 (see FIG. 6).

  Wafer stage WST2 is configured similarly to wafer stage WST1.

  Encoder systems 70 and 71 respectively operate in six-degree-of-freedom directions (X, Y) of wafer stages WST1 and WST2 in an exposure movement area including an area immediately below projection optical system PL and an alignment movement area including an area immediately below alignment system ALG. , Z, θx, θy, θz) is obtained (measured). Here, the configuration and the like of the encoder systems 70 and 71 will be described in detail.

The wafer table WTBl, WTB2, as shown in a plan view, respectively, of FIG. 2 and FIG. 3, the four corners of the encoder heads each (hereinafter appropriately abbreviated as the _head) 60 1 to 60 ₄ is arranged Yes. The head ₆₀ 1, 60 distance in the X-axis direction between the ₂ and the head ₆₀ 3, 60 X-axis direction of the distance between the ₄ are equally A one another. The head ₆₀ 1, 60 between ₄ Y-axis direction of the distance the head ₆₀ 2, 60 Y-axis direction of the distance between the ₃ are equally B to each other. The distances A and B between the heads are larger than the widths of the openings 21a of the scale plate 21 in the X-axis and Y-axis directions. Head ₆₀ 1 to 60 _4, as shown by taking the head 60 ₁ representatively in FIG. 4, the interior of the bore of the wafer table WTBl, WTB2 to form a Z-axis direction having a predetermined depth are accommodated respectively Yes.

Head 60 _1, as shown in FIG. 5, is a two-dimensional head to the (-45 ° direction with respect to the other words the X-axis) and Z-axis direction 135 degree direction relative to the X-axis measurement direction. Similarly, the heads 60 _{2 to} 60 ₄ respectively have a 225 degree direction with respect to the X axis (that is, a 45 degree direction with respect to the X axis), a Z axis direction, and a 315 degree direction with respect to the X axis (that is, This is a two-dimensional head in which the measurement direction is the −45 degree direction with respect to the X axis) and the Z axis direction, the 45 degree direction with respect to the X axis and the Z axis direction. As the heads 60 _{1 to} 60 ₄ , for example, a displacement measurement sensor head disclosed in US Pat. No. 7,561,280 can be used. The heads 60 _{1 to} 60 ₄ irradiate the two-dimensional grating RG formed on the surfaces of the scale plates 21 and 22 with the measurement beam, and receive the reflected / diffracted beam from the two-dimensional grating RG, thereby measuring each measurement direction. The positions of wafer tables WTB1 and WTB2 (wafer stages WST1 and WST2) are measured.

In the head 60 _through 603 ₄ configured as described above, since the optical path length in air of the measuring beam is extremely short, the influence of air fluctuation can mostly be ignored. However, in this embodiment, the light source and the photodetector are provided outside each head, specifically, inside (or outside) the stage main body 91, and only the optical system is provided inside each head. The light source and photodetector and the optical system are optically connected via an optical fiber (not shown). In order to improve the positioning accuracy of wafer table WTB1 (fine movement stage), between stage main body 91 (coarse movement stage) and wafer table WTB1 (fine movement stage) (hereinafter abbreviated as between coarse and fine movement stages), Laser light or the like may be transmitted in the air, or the head is provided on the stage main body 91 (coarse movement stage), the position of the stage main body 91 (coarse movement stage) is measured by the head, and the head is roughened by another sensor. The relative displacement between the fine movement stages may be measured.

When wafer stages WST1, WST2 is positioned on the exposure time movement area including a region directly below the projection optical system PL, the head 60 _1, the scale plate 21 by irradiating a measurement beam (measurement light), the scale plate 21 Receiving a diffraction beam from a grating formed on the front surface (lower surface) with a period direction of 135 degrees relative to the X axis, the positions of wafer stages WST1, WST2 in the 135 degree direction and the Z axis direction are measured. A two-dimensional encoder 70 ₁ (see FIG. 6) is configured. Similarly, head _{6O2 6O4,} respectively irradiating measurement beams (measurement lights) on scale plate 21, 225 degree direction relative to the X axis which is formed on the surface (lower surface) of scale plate 21, 315 Diffracted beam from a grating whose periodic direction is 45 degree direction and 45 degree direction, and receives 225 degree direction and Z axis direction position of wafer stage WST, 315 degree direction and Z axis direction position, and 45 degree direction And two-dimensional encoders 70 ₂ to 70 ₄ (see FIG. 6) for measuring the position in the Z-axis direction.

Further, when the wafer stages WST1, WST2 is positioned in alignment during movement area including a region immediately below the alignment system ALG, the head 60 ₁ irradiates a measurement beam (measurement light) scale plate 22, the scale plate 22 Diffracted beam from a grating formed on the surface (lower surface) of which the periodic direction is the 135 degree direction with respect to the X axis is received, and the positions of the wafer stages WST1, WST2 in the 135 degree direction and the Z axis direction are measured. The two-dimensional encoder 71 ₁ (see FIG. 6) is configured. Similarly, head _{6O2 6O4,} respectively irradiating measurement beams (measurement lights) on scale plate 22, 225 degree direction relative to the X axis which is formed on the surface (lower surface) of scale plate 22, 315 Diffracted beams from a grating whose periodic direction is the angular direction and the 45-degree direction, and the wafer stages WST1 and WST2 are positioned in the 225-degree direction and the Z-axis direction, the positions in the 315-degree direction and the Z-axis direction, and 45 The two-dimensional encoders 71 _{2 to} 71 ₄ (see FIG. 6) that measure the degree direction and the position in the Z-axis direction are configured.

2 dimensional encoder (hereinafter, appropriately abbreviated as _encoder) 70 _{1-70 4 71} 1-71 each of the measurement values of ₄ is supplied to main controller 20 (see FIG. 6). Based on the measurement values of at least three encoders (that is, at least three encoders that output effective measurement values) facing the lower surface of the scale plate 21 on which the two-dimensional grating RG is formed, Position information of wafer tables WTB1 and WTB2 (wafer stages WST1 and WST2) within a movement area during exposure including an area directly below projection optical system PL is obtained. Similarly, main controller 20 sets the measurement values of at least three encoders (that is, at least three encoders that output effective measurement values) facing the lower surface of scale plate 22 on which two-dimensional grating RG is formed. Based on this, position information of wafer tables WTB1 and WTB2 (wafer stages WST1 and WST2) in the movement area during alignment including the area directly under alignment system ALG is obtained.

  Further, in exposure apparatus 100 of the present embodiment, the position of wafer tables WTB1 and WTB2 (wafer stages WST1 and WST2) is measured independently of encoder systems 70 and 71 by wafer interferometer system 18 (see FIG. 6). It is possible. The measurement result of the wafer interferometer system 18 is used to correct (calibrate) long-term fluctuations in the measurement values of the encoder systems 70 and 71 (for example, due to deformation of the scale over time), or to back up when the output of the encoder system is abnormal. It is used as a supplementary purpose.

  As shown in FIG. 1, the alignment system ALG is an off-axis alignment system arranged at a predetermined interval on the + X side of the projection optical system PL. As an example of the alignment system ALG, FIA (Field Image) which is a kind of an image processing type alignment sensor that measures a mark position by illuminating a mark with broadband light such as a halogen lamp and processing the mark image. Alignment) system is used. The imaging signal from the alignment system ALG is supplied to the main controller 20 (see FIG. 6) via an alignment signal processing system (not shown).

  The alignment system ALG is not limited to the FIA system. For example, the mark is irradiated with coherent detection light, and scattered light or diffracted light generated from the mark is detected, or two diffracted lights generated from the mark (for example, Of course, it is possible to use alignment sensors that detect and detect interference light of the same order or diffracted light diffracted in the same direction alone or in combination. In addition, as the alignment system ALG, for example, an alignment system having a plurality of detection regions disclosed in US Patent Application Publication No. 2008/0088843 may be adopted.

  In addition, the exposure apparatus 100 of the present embodiment has an oblique incidence type multi-point focal point in the vicinity of the alignment system ALG, which has the same configuration as that disclosed in, for example, US Pat. No. 5,448,332. A position detection system (hereinafter abbreviated as a multi-point AF system) AF (not shown in FIG. 1, refer to FIG. 6) is provided. The detection signal of the multipoint AF system AF is supplied to the main controller 20 via an AF signal processing system (not shown) (see FIG. 6). At the time of wafer alignment, main controller 20 performs, for example, at least three encoders facing the lower surface of scale plate 22 in parallel with the detection of alignment marks (that is, at least three encoders that output effective measurement values). A process of acquiring surface position information (unevenness information) on the surface of the wafer W at each detection point based on the detection signal of the multi-point AF system AF while detecting the position of the wafer table upper surface in the Z-axis direction using Hereinafter, the focus mapping is performed. Then, main controller 20 outputs surface position information on the surface of wafer W acquired by focus mapping and at least three encoders facing the lower surface of scale plate 21 (that is, at least outputs effective measurement values) during exposure. Based on the position information in the Z-axis direction of the upper surface of the wafer table detected by using three encoders), so-called focus leveling control of the wafer W during scanning exposure is executed.

  FIG. 6 is a block diagram in which a part of the control system related to the stage control of the exposure apparatus 100 is omitted. This control system is configured around the main controller 20. The main controller 20 includes a so-called microcomputer (or workstation) comprising a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and controls the entire apparatus. Control.

In the exposure apparatus 100 configured as described above, when the device is manufactured, the main controller 20 performs the alignment system ALG on the wafer W held on the wafer tables WTB1 and WTB2 within the alignment movement region. The used wafer alignment (for example, enhanced global alignment (EGA) disclosed in US Pat. No. 4,780,617) is performed. At this time, the position information of the wafer stages WST1 and WST2 in the six-degree-of-freedom directions (X, Y, Z, θx, θy, θz) is obtained (measured) by the encoder system 71 (encoders 71 _{1 to} 71 ₄ ). .

  After wafer alignment, wafer stages WST1 and WST2 move to the movement area during exposure, and are processed by main controller 20 in the latter half of Pri-BCHK disclosed in, for example, US Patent Application Publication No. 2008/0088843. A process (ie, reticle alignment) for measuring the projected images (aerial images) of the pair of measurement marks on the reticle R projected by the projection optical system PL using the above-described aerial image measuring devices 45A and 45B in the same procedure, etc. Is done.

Then, main controller 20 converts the result of wafer alignment (array coordinates obtained by converting the array coordinates of a plurality of shot areas on wafer W obtained as a result of EGA with reference to the position of the second reference mark on reference mark plate FM). ) Is performed, and the pattern of the reticle R is transferred to a plurality of shot areas on the wafer W, respectively. In the step-and-scan exposure operation, the scanning exposure operation for synchronously driving the reticle stage RST and the wafer stages WST1 and WST2, and the wafer stages WST1 and WST2 are moved to the acceleration start position for exposure of the shot area. This is performed by alternately repeating the movement (stepping) operation between shots. During the exposure operation, the encoder system 70 (encoders 70 ₁ to 70 ₄ ) obtains (measures) position information of the wafer tables WTB1 and WTB2 in the six-degree-of-freedom directions (X, Y, Z, θx, θy, θz). ).

  Further, the exposure apparatus 100 of the present embodiment includes two wafer stages WST1 and WST2. Therefore, in parallel with performing the step-and-scan exposure on the wafer loaded on one wafer stage, for example, wafer stage WST1, on the other wafer stage WST2, the wafer is exchanged and after the exchange. Wafer alignment with respect to the wafer (for example, processing for detecting a second reference mark similar to the first half of Pri-BCHK disclosed in US Patent Application Publication No. 2008/0088843, etc., using alignment system ALG, and EGA) A parallel processing operation is performed.

  In the exposure apparatus 100 of the present embodiment, as described above, the main controller 20 uses the encoder system 70 (see FIG. 6) in the movement area during exposure, and the encoder system 71 (see FIG. 6) in the movement area during alignment. ) Is used to obtain (measure) the positional information of the wafer tables WTB1 and WTB2 in the six-degree-of-freedom directions (X, Y, Z, θx, θy, θz).

  Here, the position measurement of the wafer table (wafer stage) in the XY plane in the three degrees of freedom direction (X-axis direction, Y-axis direction and θz direction (X, Y, θz)) is performed by the encoder systems 70 and 71. The principle will be further described. However, since wafer table WTB2 (wafer stage WST2) is configured in the same manner as wafer table WTB1 (wafer stage WST1), only wafer table WTB1 (wafer stage WST1) will be described here.

In the present embodiment, by employing the configuration and arrangement of the encoder heads 60 ₁ to 60 ₄ and scale plate 21 as described above, at least three of the encoder heads 60 ₁ to 60 ₄ in the exposure time movement area, It always faces the scale plate 21.

When the center of wafer table WTB1 (coincides with the center of the wafer) is located on the + X side and the + Y side from the exposure center (coincidence with optical axis AX of projection optical system PL) in the movement area during exposure, on wafer table WTB1 The heads 60 ₄ , 60 ₁ and 60 ₂ face the scale plate 21. In this case, effective measurement values are transmitted to the main controller 20 from these heads 60 ₄ , 60 ₁ , 60 ₂ (encoders 70 ₄ , 70 ₁ , 70 ₂ ). In the following description, the center position of wafer table WTB1 (wafer center position) is simply referred to as the position of wafer table (wafer).

Similarly, wafer table WTB1 is, when located on the -X side and the + Y side from the exposure center (optical axis AX), the head _{60 1,} 60 2, 60 ₃ are opposed to the scale plate 21. When wafer table WTB1 is positioned on the −X side and the −Y side from the exposure center (optical axis AX), heads 60 ₂ , 60 ₃ , and 60 ₄ face scale plate 21. When the wafer table WTB1 is positioned on the + X side and the −Y side from the exposure center P, the heads 60 ₃ , 60 ₄ , and 60 ₁ face the scale plate 21. Further, wafer table WTB1 is, when positioned in close proximity to the exposure center (optical axis AX), all the heads ₆₀ 1 to 60 ₄ is opposed to the scale plate 21. An effective measurement value is transmitted from the head (encoder) facing the scale plate 21 to the main controller 20.

Main controller 20 determines the position (X, Y, θz) of wafer table WTB1 (wafer stage WST1) in the XY plane based on the measurement results of heads 60 _{1 to} 60 ₄ (encoders 70 ₁ to 70 ₄ ). calculate. Here, the encoder ₇₀ 1 to 70 ₄ of the measured value (referred to as _C 1 -C _4, respectively), the position of the wafer table WTBl (X, Y, [theta] z) with respect to the following equation (1) to (4) It depends on.

C ₁ = − (cos θz + sin θz) X / √2
+ (Cos θz−sin θ z) Y / √2 + √2 psin θz (1)
C ₂ = − (cos θz−sin θz) X / √2
− (Cos θz + sin θz) Y / √2 + √2 psin θz (2)
C ₃ = (cos θz + sin θz) X / √2
− (Cos θz−sin θz) Y / √2 + √2 psin θz (3)
C ₄ = (cos θz−sin θz) X / √2
+ (Cos θz + sin θz) Y / √2 + √2 psin θz (4)
Here, p is a distance in the X-axis and Y-axis directions of the head from the center of wafer table WTB1 (WTB2), as shown in FIG.

Main controller 20 specifies three heads (encoders) facing scale plate 21 according to the position of wafer table WTB1 (wafer stage WST1) in the XY plane, and uses the above formula ( The position (X, Y, θz) in the XY plane of the wafer table WTB1 is obtained by combining simultaneous equations selected from 1) to (4) and solving the simultaneous equations using the measurement values of the three heads (encoders). ) Is calculated. For example, when the wafer table WTB1 is located on the + X side and the + Y side from the exposure center (optical axis AX), the main controller 20 has heads 60 ₁ , 60 ₂ , 60 ₄ (encoders 70 ₁ , 70 ₂ , 70 ₄ ). The simultaneous equations are constructed from the equations (1), (2), and (4) followed by the measured values, and the measured values of the respective heads are substituted into the left sides thereof to solve the simultaneous equations. When wafer stage WST1 is located in the very vicinity of exposure center P, main controller 20 may select any three from heads 60 _{1 to} 60 ₄ (encoders 70 ₁ to 70 ₄ ).

  Main controller 20 drives (position control) wafer stage WST1 within the movement area during exposure based on the above calculation result (X, Y, θz).

  When wafer table WTB1 (wafer stage WST1) is positioned within the alignment movement region, main controller 20 uses encoder system 71 to measure position information in the three-degree-of-freedom directions (X, Y, θz). Here, the measurement principle and the like are the same as in the case where the encoder system 70 is used except that the exposure center is the detection center of the alignment system ALG and the scale plate 21 is replaced with the scale plate 22.

Furthermore, the main controller 20, X of wafer table WTBl, WTB2 (wafer stage WST1, WST2), depending on the position of the Y plane, three of the heads ₆₀ through 603 ₄ facing scale plate 21 Switch between the two. Here, when switching the encoder head, for example, as disclosed in US Patent Application Publication No. 2008/0094592, etc., a linking process is performed to ensure the continuity of the wafer stage position measurement result. Is called.

  In the exposure apparatus 100 of the present embodiment, a moving coil type planar motor 30 is employed from the viewpoint of reducing the weight of the wafer stages WST1 and WST2 and improving the position controllability. In the case of the moving coil type planar motor 30, a stationary open magnetic field is generated in the exposure apparatus 100 by a stator (magnet unit 14a) provided in the stage base 12 as shown in FIG. 7A, for example. Released. In FIG. 7 (A), the lines of force (lines of magnetic force) of the open magnetic field are indicated by dotted lines (broken lines).

  The main frame (metrology frame) 23 that supports the constituent parts (excluding the stage apparatus) of the exposure apparatus 100 such as the projection unit PU and the alignment system ALG usually uses a magnetic invar as its material. Of course, a non-magnetic material such as ceramics can also be used as a material for the main frame, but it is almost impossible to make all the components supported by the main frame non-magnetic. For this reason, an open magnetic field emitted by the magnet unit 14a serves as a medium, and a magnetic force acts between the stage base 12 and the main frame 23 (including supported components), and the main frame 23 is caused by the action of the magnetic force. Can be distorted even though the amount is very small. Due to the distortion of the main frame 23, the postures of the scale plates 21 and 22 are changed, or the scale plates 21 and 22 themselves are distorted, resulting in a measurement error of the encoder systems 70 and 71.

  Further, wafer stages WST1 and WST2 are also configured to include a Z / tilt driving mechanism 28 including a magnetic material such as a permanent magnet. Further, the mover (coil unit (not shown)) constituting the planar motor 30 and the coil of the Z / tilt drive mechanism 28 also generate a magnetic field. For this reason, when the wafer stages WST1 and WST2 move on the stage base 12, the open magnetic field changes, and the magnetic force acting on the main frame 23 (including supported components) depends on the position of the wafer stages WST1 and WST2. Can change.

  FIG. 7B shows an open magnetic field in the exposure apparatus 100 as in FIG. 7A. 7A and 7B show that wafer stage WST2 moves in the −X direction within the alignment movement area, so that wafer stage WST1 is at substantially the same position within the exposure movement area. First, the state in which the open magnetic field in the moving area during exposure changes from the state shown in FIG. 7A to the state shown in FIG. 7B is shown. As described above, the change in the open magnetic field causes a change in the posture of the scale plate 21 or distortion of the scale plate 21 itself. Contrary to the above, when wafer stage WST1 moves, even if wafer stage WST2 is stopped, the magnetic field in the moving region during alignment changes, causing a change in the posture of scale plate 22 or distortion of scale plate 22 itself. .

  Accordingly, a measurement error of the encoder system 70 or 71 that measures the position of the other wafer table (wafer stage) can occur depending on the position of one wafer stage. This measurement error results in a decrease in exposure accuracy and alignment measurement accuracy, which in turn causes a decrease in overlay accuracy, focus accuracy, and the like, and ultimately a decrease in yield of semiconductor devices.

  Hereinafter, a method of correcting the measurement error of the encoder systems 70 and 71 that measure the position of the other wafer table (wafer stage) due to the change in the magnetic field accompanying the movement of one wafer stage will be described.

  The main controller 20 creates a correction map for correcting the measurement error of the encoder systems 70 and 71 when the exposure apparatus 100 is activated or idle. Here, the correction map for the encoder system 70 is created by the following procedure. In the following description regarding the creation of the correction map, the measurement information of the wafer stage position by the encoder system 70 is (X, Y), and the measurement information of the wafer stage position by the encoder system 71 is (x, y). , Explain.

  Main controller 20 moves wafer stage WST1 so that fiducial mark plate FM on wafer table WTB1 is positioned immediately below projection optical system PL (exposure center (matches optical axis AX of projection optical system PL)). At the same time, main controller 20 drives reticle stage RST to position reticle reference mark plate RFM provided on reticle stage RST on optical axis AX. At this time, it is assumed that wafer stage WST2 is located at a reference position sufficiently separated from wafer stage WST1, for example, a load / unload position where the wafer is exchanged.

  The reticle reference mark plate RFM is provided with a pair of measurement marks PM corresponding to the pair of aerial image measurement slit plates SL on the reference mark plate FM. As each measurement mark PM, as shown in FIG. 8B, an X measurement mark PMX in which a plurality of opening patterns with a predetermined width (for example, 1 μm) having the longitudinal direction in the Y-axis direction are arranged in the X-axis direction, A two-dimensional mark composed of Y measurement marks PMY in which a plurality of opening patterns having a predetermined width (for example, 1 μm) with the axial direction as the longitudinal direction is arranged in the Y-axis direction is used.

  Main controller 20 illuminates a pair of measurement marks PM on reticle reference mark plate RFM with illumination light IL, and displays a projection image (space image) of measurement mark PM on reference mark plate FM via projection optical system PL. Are formed on a pair of aerial image measurement slit plates SL. Thereby, as shown in FIG. 8C as an example, the image PMX ′ of the X measurement mark PMX and the image PMY ′ of the Y measurement mark PMY are displayed on the aerial image measurement slit plate SL. Projected to the vicinity of the X slit SLX and the Y slit SLY of SL. Main controller 20 drives wafer stage WST1 in the X-axis direction while monitoring measurement information (X, Y) from encoder system 70, and displays X slit SLX of a pair of aerial image measurement slit plates SL as image PMX. Are scanned, and an image PMX ′ of the X measurement mark PMX in the pair of measurement marks PM is detected by the slit scan method using the aerial image measurement devices 45A and 45B. Similarly, main controller 20 drives wafer stage WST1 in the Y-axis direction while monitoring measurement information (X, Y) from encoder system 70, and Y measurement mark PMY in a pair of measurement marks PM. The image PMY ′ is detected by the slit scan method using the aerial image measuring devices 45A and 45B.

Then, main controller 20 performs a predetermined calculation based on the aerial image profile corresponding to image PMX ′ of X measurement mark PMX and the aerial image profile corresponding to image PMY ′ of Y measurement mark PMY to perform measurement mark measurement. The reference position (X ₀ , Y ₀ ) of the PM image is obtained.

Next, main controller 20 drives wafer stage WST2 based on measurement information (x, y) from encoder system 71 and positions it at measurement positions (x ₁ , y ₁ ).

Next, main controller 20 performs aerial image measurement of measurement mark PM in the same procedure as described above, and obtains the position (X ₁ , Y ₁ ) of the image of measurement mark PM.

Thereafter, similarly, main controller 20 moves wafer stage WST2 to measurement positions (x ₂ , y ₂ ), (x ₃ , y ₃ ),... Based on measurement information (x, y) from encoder system 71. ..., (x _I , y _I ) are sequentially positioned, and the aerial image measurement of the measurement mark PM corresponding to each positioning position is performed, and the positions (X ₂ , Y ₂ ), (X ₃ , Y) of the image of the measurement mark PM ₃ ), ..., (X _I , Y _I ) are obtained.

  The measurement position at which wafer stage WST2 is to be positioned is set at least over the entire movement area during alignment. As long as wafer stage WST1 and its position do not overlap, the measurement position may be set within a wide range as much as possible, including not only the alignment movement area but also the exposure movement area.

The main controller 20 determines the positions (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), (X ₃ , Y ₃ ),..., (X _I , Y) of the measurement mark PM obtained above. _I )) and differences ΔX _i and ΔY _i (i = 1 to I) between the reference position (X ₀ , Y ₀ ) of the image of the measurement mark PM are obtained and correspond to the measurement position (x _i , y _i ). And store it in a storage device (not shown). As a result, a correction map is obtained as functions ΔX _i (x _i , y _i ) and ΔY _i (x _i , y _i ) for x and y.

Further, since the correction maps ΔX _i (x _i , y _i ) and ΔY _i (x _i , y _i ) are obtained as discrete data for a plurality of discrete points (x _i , y _i ), linear interpolation or the like is used. You may convert into the continuous function about x and y. That is, the correction information may be held in the form of correction functions ΔX _i (x, y), ΔY _i (x, y) instead of the correction map.

Main controller 20 drives correction map ΔX _i (x _i , y _i) using position measurement information x, y of wafer stage WST2 from encoder system 71 when driving wafer stage WST1 in the movement area during exposure during exposure. ), ΔY _i (x _i , y _i ) to derive correction values ΔX _i , ΔY _i , and using the correction values, position measurement information X, Y of wafer stage WST1 from encoder system 70 is respectively expressed as X−ΔX _i. , Y−ΔY _i is corrected. Main controller 20 drives wafer stage WST1 (position control) using corrected position measurement information X-ΔX _i and Y-ΔY _i .

  The correction map for the encoder system 71 is operated in such a manner that the operations related to the wafer stage WST1 and the wafer stage WST2 are exchanged in the above-described correction map generation procedure for the encoder system 70. However, in this case, since the aerial image of the mark cannot be measured using the aerial image measuring devices 45A and 45B, the reference mark M on the reference mark plate FM of the wafer table WTB2 is detected by the alignment system ALG instead. To be done.

In this case, in the reference state in which wafer stage WST1 is sufficiently separated from wafer stage WST2, the position (x ₀ , y ₀ ) of reference mark M is the measurement information of encoder system 71 and the measurement result of alignment system ALG (index center). Based on the positional deviation of the reference mark M).

Wafer stage WST1 is sequentially positioned at measurement positions (X _j , Y _j ) (j = 1 to _J ) in the movement area during exposure, and on reference mark plate FM of wafer table WTB2 corresponding to each positioning position. The position (x _j , y _j ) of the reference mark M is determined. It should be noted that as long as wafer stage WST2 and its position do not overlap, the measurement position may be set within the widest possible region including not only the exposure movement region but also the alignment movement region.

Then, main controller 20 determines the position (x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ),..., (X _j , y _j ) of the obtained reference mark M. And Δx _j , Δy _j (j = 1 to _J ) between the reference mark M and the position (x ₀ , y ₀ ) of the reference state in the reference state are obtained and associated with the measurement position (X _j , Y _j ). Store in a storage device (not shown). Thereby, the correction map is obtained as functions Δx _j (X _j , Y _j ) and Δy _j (X _j , Y _j ) for X and Y.

Further, since the correction maps Δx _j (X _j , Y _j ) and Δy _j (X _j , Y _j ) are obtained as discrete data for a plurality of discrete points (X _j , Y _j ), linear interpolation or the like is used. You may convert into the continuous function about X and Y. That is, the correction information may be held in the form of correction functions Δx _j (X, Y), Δy _j (X, Y) instead of the correction map.

When main controller 20 drives wafer stage WST2 in the alignment movement region during alignment measurement, main controller 20 uses correction measurement Δx _j (X _j) using position measurement information X _j and Y _j of wafer stage WST1 from encoder system 70. , Y _j ), Δy _j (X _j , Y _j ) to derive correction values Δx _j , Δy _j and use the correction values to obtain position measurement information (x, y) of wafer stage WST2 from encoder system 71. Corrections are made as x−Δx _j and y−Δy _j , respectively. The main controller 20 corrects the position measurement information x-[Delta] x _j, with y-[Delta] y _j, drives the wafer stage WST2 (position control) to.

In exposure apparatus 100 of the present embodiment, both wafer stages WST1 and WST2 are configured in the same manner, so that correction maps ΔX _i (x _i , y _i ), ΔY _i (x _i , y _i ) and Δx _j (X _j , Y _j ), Δy _j (X _j , Y _j ) can be used for both wafer stages WST1, WST2. If there are individual differences between wafer stages WST1 and WST2, correction maps are created for both stages. The creation procedure is the same as that described above, except that wafer stages WST1 and WST2 are replaced.

  In the present embodiment, attention is paid to the measurement error of the encoder systems 70 and 71 for the other wafer stage caused by the change in the magnetic field accompanying the movement of one wafer stage. The wafer stage was positioned at the measurement position one by one. Here, one wafer stage may be driven from each measurement position in the X-axis direction and the Y-axis direction, for example, with unit acceleration (unit driving force). In this case, a correction map that can correct the measurement error of the encoder systems 70 and 71 with respect to the other wafer stage due to a mechanical effect such as pressure fluctuation in the atmosphere accompanying the movement of one wafer stage is obtained.

  Next, the principle of position measurement in the three degrees of freedom direction (Z, θx, θy) by the encoder systems 70 and 71 will be further described.

In the present embodiment, by employing the configuration and arrangement of the encoder heads 60 ₁ to 60 ₄ and scale plate 21 as described above, the exposure time movement area, in accordance with the position of wafer stage WST1 (WST2), the encoder At least three of the heads 60 _{1 to} 60 ₄ face the scale plate 21. Effective measurement values are transmitted from the head (encoder) facing the scale plate 21 to the main controller 20.

The main controller 20, based on the encoder ₇₀ 1 to 70 ₄ of the measurement results, calculates the position of the wafer table WTB1 (WTB2) (Z, θx , θy) a. Here, the encoder ₇₀ 1 to 70 ₄ in the Z-axis direction about the measured value (as distinguished from the measured value _C 1 -C ₄ for uniaxial direction in the aforementioned XY plane, _{respectively,} is denoted as D 1 to D ₄₎ is , It depends on the position (Z, θx, θy) of wafer table WTB1 (WTB2) as shown in the following equations (5) to (8).

D ₁ = −ptan θy + ptan θx + Z (5)
D ₂ = ptan θy + ptan θx + Z (6)
D ₃ = ptan θy−ptan θx + Z (7)
D ₄ = −ptan θy−ptan θx + Z (8)
However, p is the distance (refer FIG. 5) regarding the X-axis and Y-axis directions of the head from the center of wafer table WTB1 (WTB2).

Main controller 20 selects an equation according to the measurement values of the three heads (encoders) according to the position of wafer table WTB1 (WTB2) from the above equations (5) to (8), and a simultaneous equation constituted by them. The position (Z, θx, θy) of the wafer table WTB1 (WTB2) is calculated by substituting the measurement values of the three heads (encoders) into For example, when the wafer table WTB1 (WTB2) is positioned on the + X side and the + Y side from the exposure center (optical axis AX), the main controller 20 uses the heads 60 ₁ , 60 ₂ , 60 ₄ (encoders 70 ₁ , 70 ₂ , The simultaneous equations are constructed from the equations (5), (6), and (8) followed by the measured value of 70 ₄ ), and the measured value is substituted into the left side of the equations to solve. The calculation of the position (Z, θx, θy) of wafer table WTB1 (WTB2) is performed at the time of focus mapping at the time of wafer alignment and at the time of exposure as described above.

  Main controller 20 performs focus leveling control on wafer table WTB1 (WTB2) in the movement area during exposure based on the wafer unevenness information acquired in advance and the above calculation results (Z, θx, θy). .

  When wafer table WTB1 (WTB2) is located in the movement region during alignment, main controller 20 uses encoder system 71 to measure position information in the three-degree-of-freedom directions (Z, θx, θy). The measurement principle and the like in this case are the same as when the encoder system 70 is used except that the exposure center is the detection center of the alignment system ALG and the scale plate 21 is replaced with the scale plate 22. Based on the measurement result of encoder system 71, main controller 20 acquires the relationship between the wafer surface position and the Z position of wafer table WTB1 (WTB2) for focus leveling control during exposure.

Further, main controller 20 switches and uses three of heads 60 _{1 to} 604 facing scale plates 21 and 22 according to the positions of wafer stages WST _{1 and} WST ₂ . Here, when the encoder head is switched, in order to guarantee the continuity of the measurement result of the position of the wafer table WTB1 (WTB2), the same connection processing as described above is performed.

  In the position measurement in the three-degree-of-freedom directions (Z, θx, θy) of wafer table WTB1 (WTB2) by encoder systems 70, 71, main controller 20 also creates a correction map and corrects the correction map as described above. Is used to correct the position measurement information in the three-degree-of-freedom direction (Z, θx, θy) of wafer table WTB1 (WTB2) from encoder system 70, 71, and using the corrected position measurement information, for example, the above-described focus・ Leveling control can be performed.

  However, when creating a correction map for the encoder system 70, the main controller 20 measures the above-described measurement marks using the aerial image measurement devices 45A and 45B, and performs focus information on the marks (in the Z-axis direction of the wafer table). Position). Further, when the correction map for the encoder system 71 is created, the position of the wafer table in the Z-axis direction is measured using the multipoint AF system AF installed in the alignment movement region (near the alignment system ALG).

  As described above, according to the exposure apparatus 100 of the present embodiment, the main controller 20 positions information of one wafer stage WST1 (or WST2) measured by the encoder system 70 and the other wafer stage WST2 (or One wafer stage WST1 (or WST2) is driven via the planar motor 30 in the movement area during exposure based on correction information (a correction map or correction function created in advance) according to the position of WST1). . Here, the position information measured by the encoder system 71 is used as the position information of the other wafer stage WST2 (or WST1) for extracting the correction value from the correction map or the like. Therefore, one wafer stage WST1 (or WST2) can be driven with high accuracy within the movement area during exposure.

  The main controller 20 also measures the position information of the other wafer stage WST2 (or WST1) measured by the encoder system 71 and correction information corresponding to the position of the one wafer stage WST1 (or WST2) (correction created in advance). The other wafer stage WST2 (or WST1) is driven via the planar motor 30 within the movement region during alignment based on the map or the correction function. Here, the position information measured by the encoder system 70 is used as the position information of one wafer stage WST1 (or WST2) for extracting a correction value from the correction map or the like. Therefore, the other wafer stage WST2 (or WST1) can be driven with high accuracy within the alignment movement region. In the present embodiment, the correction information is obtained with respect to the 6 degrees of freedom direction.

  Therefore, according to the exposure apparatus 100 of the present embodiment, high alignment measurement accuracy and focus mapping accuracy at the time of alignment can be ensured, and exposure is performed using these results, so that high exposure accuracy (superposition accuracy, Focus control accuracy, etc.) can be realized, and finally the yield of the semiconductor device can be improved.

In the above-described embodiment, the case where the aerial image measurement devices 45A and 45B are used to create the correction map or the correction function of the encoder system 70 has been described. However, the present invention is not limited to this, and measurement is performed by actually performing exposure. By transferring the mark PM or other marks onto the wafer and measuring the position of the transferred image, data ΔX _i and ΔY _i (i = 1 to I) for creating a correction map or a correction function are obtained. Also good. In this case, the aerial image measurement devices 45A and 45B are not necessarily provided, but a device for reticle alignment is necessary. Therefore, a pair of reticle alignment systems of a TTR (Through The Reticle) system using light having an exposure wavelength disclosed in, for example, US Pat. No. 5,646,413 may be provided above the reticle R. .

Further, in the above embodiment, in order to create a correction map or a correction function of the encoder system 70, the wafer stage WST2 is replaced with the measurement position (x ₂ , y ₂ ), (x ₃ , _{y 3), ......, (x} I, sequentially positioned _{y I),} the encoder ₇₀ 1 to 70 ₄ of the encoder system 70 in the positioning position, may perform position measurement of wafer table WTBl. Even in such a case, due to a magnetic field change due to changes in the position of wafer stage WST2 it is because the measurement value of the encoder 70 ₁ to 70 ₄ is changed.

  In the above embodiment, the reference position is determined separately from the measurement position, and the difference between the mark positions at each measurement position is obtained based on the actual measurement value of the mark position at the reference position. The difference between the mark positions at the remaining measurement positions may be obtained with reference to the actual measurement value of the mark position at one of the plurality of measurement positions.

  In the above-described embodiment, the encoder systems 70 and 71 mainly measure the position information of the wafer stages WST1 and WST2, and the encoder systems 70 and 71 are mainly caused by magnetic field changes accompanying the movement of the wafer stages WST2 and WST1. The case where the present invention is applied to the measurement error correction is illustrated. However, the present invention is not limited to this, and when the wafer interferometer system 18 is used mainly for measuring the positional information of the wafer stages WST1 and WST2 instead of the encoder systems 70 and 71, the wafer interferometer system mainly caused by the change in the magnetic field. It is effective to apply the present invention to 18 measurement errors. In wafer interferometer system 18, a measurement beam is irradiated from the interferometer unit onto a reflecting surface (moving mirror or the like (not shown)) provided on wafer stages WST 1 and WST 2. In this case, when the interferometer unit is attached to the main frame, a measurement error occurs in the interferometer system for the same reason as in the above embodiment due to a magnetic field change accompanying the movement of wafer stages WST2 and WST1. Even when the interferometer unit is not attached to the main frame, the structure including the magnetic material on wafer stages WST1 and WST2 is deformed by a magnetic field change, and the reflecting surface is displaced or displaced with the deformation of the structure. This is because the probability of deformation is high.

  Moreover, in the exposure apparatus 100 of the said embodiment, the case where this invention was applied to the wafer stage apparatus 50 which employ | adopted the moving coil type planar motor 30, and the exposure apparatus 100 provided with this was illustrated. However, in the stage apparatus, a moving magnet type flat motor disclosed in, for example, US Pat. No. 6,437,463 can be employed instead of the moving coil type flat motor. In this case, permanent magnets are provided on wafer stages WST 1 and WST 2, and coils are arranged inside stage base 12. In this case as well, it is clear that the magnetic field changes as the wafer stages WST1 and WST2 move, and the change in the magnetic field causes the encoder or interferometer to measure the position of the wafer stages WST1 and WST2. It is clear that measurement errors occur. Therefore, it is effective to apply the present invention also in this case.

  In the above, correction of measurement errors in the encoder system and the like due to the change in the magnetic field due to the movement of the wafer stages WST1 and WST2 has been described. However, factors other than the change in the magnetic field due to the movement of one wafer stage have been described. Therefore, even if measurement errors occur in the measurement apparatus that measures the position of the other wafer stage, these errors are corrected as a result by applying the present invention. This is because in the present invention, measurement data for creating correction information is acquired using an actual machine for creating correction information (such as a correction map or a correction function).

In the above embodiment, while an example has been shown where a two-dimensional grating RG in each of the lower surface of scale plate 21, 22 is formed is not limited thereto, the corresponding encoder heads 60 ₁ to 60 ₄ of the measurement direction (XY The present invention can also be applied to the case where a one-dimensional diffraction grating having only one axis direction in the plane) as a periodic direction is formed.

In the above embodiment, illustrated for the case as each head _{60 6O4} (encoders ₇₀ 1 to 70 _4), the two-dimensional head that the uniaxial direction and the Z-axis direction in the XY plane and the measurement direction is adopted However, the present invention is not limited to this, and a one-dimensional encoder whose measurement direction is one axial direction in the XY plane and a Z sensor (for example, an optical pickup type or other type surface position sensor) whose measurement direction is the Z-axis direction. May be adopted. In addition to the Z sensor, a two-dimensional encoder whose measurement direction is a biaxial direction orthogonal to each other in the XY plane may be employed.

  The configuration of the encoder system described in the above embodiment is merely an example, and the present invention is of course not limited to this. For example, it is also possible to employ an encoder system in which a diffraction grating (scale) is provided on a wafer table (wafer stage) and an encoder head is disposed outside the wafer stage so as to face the diffraction grating. Even in this case, the encoder head is not limited to the two-dimensional head in which the measurement direction is the uniaxial direction and the Z-axis direction in the XY plane employed in the above embodiment, but the uniaxial direction in the XY plane or two axes orthogonal to each other A combination of a one-dimensional or two-dimensional encoder whose direction is the measurement direction and a Z sensor may be employed.

  Further, in the above embodiment, during wafer alignment, focus mapping is performed using the multi-point AF system AF, and the surface position information on the surface of the wafer W and the position information in the Z-axis direction on the upper surface of the wafer table acquired by the focus mapping are used. Based on this, the case where the focus / leveling control of the wafer W during the scanning exposure is executed has been described. However, a multi-point AF system AF is provided in the vicinity of the projection optical system PL, not in the vicinity of the alignment system ALG, and focus / leveling control of the wafer W during scanning exposure is executed using the multi-point AF system AF. Is of course good. In this case, a Z sensor for measuring the surface position of the wafer table may be provided in the vicinity of the alignment system ALG in order to obtain correction information for the position measurement error in the Z-axis direction of the encoder system 71. Alternatively, a Z interferometer that measures the Z position of the wafer table may be provided.

  In the above embodiment, the case where the present invention is applied to an exposure apparatus having a scanning / stepper type twin wafer stage (hereinafter abbreviated as a twin type exposure apparatus) has been described. The present invention may be applied to a batch exposure type twin type exposure apparatus such as the above. Even with a stepper, etc., measuring the position of the stage on which the object to be exposed is mounted with an encoder makes it possible to almost eliminate the occurrence of position measurement errors due to air fluctuations. Based on this, it becomes possible to position the wafer stage with high accuracy, and as a result, transfer of a highly accurate reticle pattern onto the wafer becomes possible. The present invention can also be applied to a step-and-stitch twin type exposure apparatus that combines a shot area and a shot area. Further, as disclosed in, for example, U.S. Patent Application Publication No. 2007/0211235 and U.S. Patent Application Publication No. 2007/0127006, measurement members (for example, fiducial marks, and / or Alternatively, the present invention may be applied to an exposure apparatus (abbreviated as an exposure apparatus with a measurement stage) including a measurement stage including a sensor or the like.

  Further, the present invention may be applied to an immersion type twin type exposure apparatus or an exposure apparatus with a measurement stage disclosed in, for example, International Publication No. 99/049504, US Patent Application Publication No. 2005/0259234, and the like. . Note that various exposure apparatuses described below are exposure apparatuses including a plurality of stages such as a twin-type exposure apparatus or an exposure apparatus with a measurement stage, although not particularly specified.

  Further, in the projection exposure apparatus according to the present invention including the exposure apparatus of the above embodiment, the projection optical system 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, Either a reflection system or a catadioptric system may be used, and the projected image may be an inverted image or an erect image.

The illumination light IL is not limited to ArF excimer laser light (wavelength 193 nm), but may be ultraviolet light such as KrF excimer laser light (wavelength 248 nm) or vacuum ultraviolet light such as F ₂ laser light (wavelength 157 nm). good. For example, as disclosed in US Pat. No. 7,023,610, single-wavelength laser light in the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser is used as vacuum ultraviolet light, for example, erbium. A harmonic which is amplified by a fiber amplifier doped with (or both erbium and ytterbium) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

  In the above embodiment, a light transmissive mask (reticle) in which a predetermined light shielding pattern (or phase pattern / dimming pattern) is formed on a light transmissive substrate is used. Instead of this reticle, for example, As disclosed in US Pat. No. 6,778,257, based on electronic data of a pattern to be exposed, an electronic mask (a variable shaping mask, an active mask) that forms a transmission pattern, a reflection pattern, or a light emission pattern is disclosed. Also called a mask or an image generator, for example, a DMD (Digital Micro-mirror Device) which is a kind of non-light emitting image display element (spatial light modulator) may be used. When such a variable molding mask is used, the stage on which the wafer or glass plate or the like is mounted is scanned with respect to the variable molding mask. Therefore, by measuring the position of the stage using an encoder, the above embodiment can be used. The same effect can be obtained.

  Further, as disclosed in, for example, International Publication No. 2001/035168, an exposure apparatus (lithography system) that forms a line-and-space pattern on a wafer W by forming interference fringes on the wafer W. The present invention can also be applied.

  Further, as disclosed in, for example, US Pat. No. 6,611,316, two reticle patterns are synthesized on a wafer via a projection optical system, and 1 on the wafer by one scan exposure. The present invention can also be applied to an exposure apparatus that double exposes two shot areas almost simultaneously.

  In the above embodiment, the object on which the pattern is to be formed (the object to be exposed to the energy beam) is not limited to the wafer, but may be another object such as a glass plate, a ceramic substrate film member, or a mask blank. .

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, but for example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern to a square glass plate, an organic EL, a thin film magnetic head, an image sensor (CCD, etc.), micromachines, DNA chips and the like can also be widely applied to exposure apparatuses. 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.

  The semiconductor device was formed on the mask by the step of designing the function / 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 the above embodiment. A lithography step for transferring a pattern onto an object such as a wafer, a development step for developing an exposed wafer (object), an etching step for removing exposed members other than the portion where the resist remains by etching, and etching. It is manufactured through a resist removal step for removing unnecessary resist, a device assembly step (including a dicing process, a bonding process, and a package process), an inspection step, and the like. In this case, since the exposure apparatus and the exposure method of the above embodiment are used in the lithography step, a highly integrated device can be manufactured with a high yield.

  As described above, the exposure apparatus and the exposure method of the present invention are suitable for exposing an object. The device manufacturing method of the present invention is suitable for manufacturing an electronic device such as a semiconductor element or a liquid crystal display element.

20 ... main control unit, 21, 22 ... scale plate, 27 ... wafer stage drive system 30 ... planar motor, 50 ... wafer stage apparatus, ₆₀ through 603 4 _... encoder heads, 70 and 71 ... encoder system, ₇₀ 1 ~ 70 ₄ , 71 _{1 to} 71 ₄ ... encoder, 100 ... exposure apparatus, ALG ... alignment system, WST1, WST2 ... wafer stage, WTB1, WTB2 ... wafer table, W ... wafer, R ... reticle, PL ... projection optical system, RG ... two-dimensional grating.

Claims (27)

An exposure method for exposing an object with an energy beam to form a pattern on the object,
First individually driven by a planar motor in stool with a parallel guide surface in a predetermined plane, the first moving body obtained I by the pair to position measurement system to each of the second movable body and a second position information on the first position information and the second moving body concerning the first mobile that maintains the previous SL object based on the first correction information obtained prior to the driving of the first moving body Drive the body ,
The exposure method, wherein the first correction information is obtained from a measurement error of the position measurement system included in the first position information, which is generated according to a position of the second moving body in the predetermined plane .   The position measurement system measures first position information of the first moving body that holds the object in a region in the vicinity of an irradiation position where the energy beam is irradiated onto the object via an optical member, and performs second movement. The exposure method according to claim 1, wherein the second position information of the second moving body is measured in a region in the vicinity of a mark detection system that detects a mark present on the body.   The exposure method according to claim 2, wherein a part of the position measurement system is provided on a frame that supports the optical member and the mark detection system.   Prior to the driving, the second moving body is positioned at a plurality of positions on the guide surface while measuring the position by the position measuring system, and the first moving body or the object is positioned at each of the positioning positions. The exposure method according to claim 2, further comprising: obtaining a position of the mark image formed on the surface using measurement information of the position measurement system, and calculating the first correction information based on the result. The mark image is a spatial image of a mark formed on the first moving body via the optical member,
The position of the mark image is obtained from the profile of the aerial image measured by the aerial image measurement device provided at least in part on the first moving body whose position information is measured by the position measurement system. The exposure method according to claim 4, comprising an imaging position of a mark image. The mark image is a transfer image of a mark transferred and formed on the object while controlling the position of the first moving body using measurement information of the position measurement system for each positioning position.
The exposure method according to claim 4, wherein the position of the mark image is obtained by measuring the position of a transfer image formed on the object.   The first correction information includes a measurement error caused by the position measurement system caused by a change in the magnetic field caused by a change in the position of the second moving body in the predetermined plane, in the predetermined plane of the second moving body. The exposure method according to any one of claims 1 to 6, which is determined according to a position.   First position information of the first moving body from the position measuring system, second position information of the second moving body from the position measuring system, and a change in position of the first moving body in the predetermined plane. The second moving body is driven based on the second correction information corresponding to the position of the first moving body in the predetermined plane of the measurement error caused by the position measuring system caused at least by the magnetic field variation caused by The exposure method according to any one of claims 1 to 7, further comprising:   Prior to driving the second moving body, the position measuring system measures the position of the first moving body and positions the first moving body at a plurality of positions on the guide surface. The exposure method according to claim 8, further comprising: measuring position information of a predetermined mark using the mark detection system and the mark detection system, and calculating the second correction information using the position information.   The position measurement system irradiates measurement light on a measurement surface provided on one of the first moving body and the outside of the first moving body, and receives the return light from the measurement surface. And an encoder system that measures the position of the first moving body based on the output of the head section. The exposure method according to claim 9. Using the exposure method according to any one of claims 1 to 10 to form a pattern on an object;
Developing the object on which the pattern is formed;
A device manufacturing method including: An exposure apparatus that exposes an object with an energy beam to form a pattern on the object,
A surface plate having a guide surface parallel to a predetermined plane;
A planar motor configured to include a stator provided in the surface plate, and first and second movers facing the guide surface;
First and second movable bodies each having the first and second movers and driven along the guide surface by the planar motor;
A position measurement system for measuring the respective positions of the first and second moving bodies;
Position information of the first moving body from the position measuring system, position information of the second moving body from the position measuring system, and first correction information obtained prior to driving of the first moving body; And the first correction information is included in the first position information generated according to the position of the second moving body in the predetermined plane. An exposure apparatus comprising: a driving device obtained from a measurement error of the position measurement system . An optical member for irradiating the object with the energy beam;
A mark detection system for detecting a mark present on the second moving body,
The position measurement system includes: a first measurement system that measures position information of the first moving body that holds the object in a region in the vicinity of the energy beam irradiation position; and a first region in the vicinity of the mark detection system. The exposure apparatus according to claim 12, further comprising a second measurement system that measures position information of the two moving bodies.   The exposure apparatus according to claim 13, wherein at least a part of the first measurement system is installed on a frame that supports the optical member.   15. The exposure apparatus according to claim 13, wherein at least a part of the second measurement system is installed on a frame that supports the mark detection system.   The exposure apparatus according to claim 13, wherein the optical member and the mark detection system are supported by the same frame.   The first correction information is obtained by positioning the second moving body at a plurality of positions on the guide surface while measuring the position by the second measurement system, and for each positioning position, The exposure apparatus according to any one of claims 13 to 16, which is calculated in advance by obtaining the position of the mark image formed on the surface using measurement information of the first measurement system. An aerial image of a mark formed via the optical member is measured on the first moving body, at least a part of which is provided on the first moving body, and the position information is measured by the first measurement system. It further includes an aerial image measurement device,
The exposure apparatus according to claim 17, wherein the position of the mark image includes an imaging position of the mark image obtained from a profile of the aerial image of the mark measured by the aerial image measurement apparatus. The mark image is a transfer image of a mark transferred and formed on the object while controlling the position of the first moving body using measurement information of the first measurement system for each positioning position.
The exposure apparatus according to claim 17, wherein the position of the mark image is obtained by measuring a position of a transfer image formed on the object.   The driving device is configured to cause a measurement error caused by the position measurement system to occur at a position in the predetermined plane of the second moving body caused by a magnetic field variation caused by a change in the position of the second moving body in the predetermined plane. The exposure apparatus according to any one of claims 12 to 19, wherein the first correction information is obtained in response.   The drive device includes position information of the first moving body from the position measurement system, position information of the second moving body from the position measurement system, and positions of the first moving body in the predetermined plane. The second moving body is driven based on the second correction information corresponding to the position of the first moving body in the predetermined plane of the measurement error caused by the position measuring system caused at least by the magnetic field fluctuation caused by the change. The exposure apparatus according to any one of claims 13 to 20.   The second correction information is obtained by positioning the first moving body at a plurality of positions on the guide surface while measuring the position by the first measurement system, and detecting the second measurement system and the mark for each positioning position. The exposure apparatus according to claim 21, wherein the exposure apparatus is calculated in advance using position information of a predetermined mark measured using a system.   The position measurement system irradiates measurement light on a measurement surface provided on one of the first moving body and the outside of the first moving body, and receives the return light from the measurement surface. And an encoder system that measures the position of the first moving body based on an output of the head section. The encoder system includes at least one head section provided on the other side of the first moving body and the outside of the first moving body. The exposure apparatus according to any one of claims 22 to 22.   24. The exposure apparatus according to claim 23, wherein one of the head portion and the measurement surface is installed on a frame that supports the optical member provided outside the first moving body. The measurement surface is provided with a diffraction grating whose periodic direction is at least one axial direction in the predetermined plane,
The exposure apparatus according to claim 23 or 24, wherein the head unit measures a position of the first moving body at least in the uniaxial direction.   The exposure apparatus according to any one of claims 23 to 25, wherein the head unit measures the position of the first moving body in a direction perpendicular to the predetermined plane. 27. The exposure apparatus according to any one of claims 12 to 26, wherein the planar motor is a moving coil type in which a coil is disposed on the first and second movers.

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