JP2012089769A - Exposure equipment and method for manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide exposure equipment capable of measuring a position of a wafer stage with high accuracy.SOLUTION: Exposure equipment comprises a position measuring system having a plurality of heads including a plurality of first heads 65 and 64 provided corresponding to a pair of measurement surfaces extendedly arranged in a Y-axis direction in the vicinity of both end portions of a top surface of a wafer stage in an X-axis direction, respectively, and each having a measuring direction of the X-axis direction, each for emitting a measuring beam to a first irradiation point on the corresponding measurement surface and receiving return light of the measuring beam returned from the measurement surface, the position measuring system for obtaining positional information of the wafer stage at least in an X-Y plane based on outputs from the plurality of heads. The first irradiation point is positioned on a straight line in the X-axis direction passing through the irradiation center of the illumination light. Accordingly, the first head can measure a position of the wafer stage at least in the X-axis direction without an Abbe error.

Description

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

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

  In this type of exposure apparatus, in order to transfer a reticle (or mask) pattern to a plurality of shot regions on a substrate such as a wafer or a glass plate (hereinafter collectively referred to as a wafer), a wafer stage that holds the wafer includes: For example, it is driven in a two-dimensional direction by a linear motor or the like. The position of the wafer stage is generally measured by using a laser interferometer having high stability over a long period of time.

  However, due to the miniaturization of patterns due to the recent high integration of semiconductor elements, further improvement in wafer stage position controllability is required, and the temperature change and temperature gradient of the atmosphere on the beam path of the laser interferometer Short-term fluctuations in measured values due to air fluctuations that occur due to the effects of air pressure can no longer be ignored. Therefore, recently, an encoder having a measurement resolution equal to or higher than that of a laser interferometer has been adopted (for example, see Patent Document 1).

  The high integration of semiconductor elements and the accompanying pattern miniaturization do not stop. Therefore, even an encoder system as disclosed in Patent Document 1 will achieve the required measurement accuracy in the near future. It is certain that it will not be possible.

US Patent Application Publication No. 2008/0088843

  According to the first aspect of the present invention, there is provided an exposure apparatus that scans an object in a first direction with respect to illumination light to form a predetermined pattern on the object, and holds the object and performs the first operation. A moving body that moves along a predetermined plane including a direction and a second direction orthogonal to the direction; and is disposed apart from the second direction on the upper surface of the moving body, and the first and second directions are periodically arranged on the upper surface. A pair of measurement surfaces extending in the first direction in which a two-dimensional grating having a direction is formed; and at least one measurement surface corresponding to each of the pair of measurement surfaces, and a first irradiation on the corresponding measurement surface A plurality of heads including a plurality of first heads having at least the second direction as a measurement direction for irradiating a point with a measurement beam and receiving return light of the measurement beam via the two-dimensional grating; Based on head output A position measurement system that obtains at least position information of the movable body in the predetermined plane, and the first irradiation point is on a straight line in the second direction passing through the irradiation center of the illumination light on the measurement surface. An exposure apparatus located at is provided.

  According to this, the first irradiation point on the measurement surface is irradiated with the measurement beam from the plurality of first heads, and the return light from the measurement surface of the measurement beam is received by the first head. Since the first irradiation point is located on the measurement surface on the illumination light irradiation center, that is, on the straight line in the second direction passing through the exposure position, the first head can measure the position of the moving body in the second direction without Abbe error. It is. Therefore, the position controllability of the moving body can be improved by controlling the position of the moving body in the second direction during exposure based on the output of the first head.

  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 apparatus of the present invention; and developing the object on which the pattern is formed. Is done.

It is a figure which shows schematically the structure of the exposure apparatus which concerns on one Embodiment. It is a top view which shows a wafer stage. It is a figure for demonstrating an interferometer system. It is a top view which shows arrangement | positioning of the stage apparatus and sensor unit with which the exposure apparatus of FIG. 1 is provided. It is a top view which shows arrangement | positioning of an encoder head (X head, Y head) and an alignment system. It is a top view which shows arrangement | positioning of Z head and a multipoint AF type | system | group. It is a block diagram which shows the main structures of the control system of the exposure apparatus which concerns on one Embodiment. It is a figure for demonstrating the position measurement in the XY plane of a wafer table and the switching (connection) of a head by the some encoder each including a some head. It is a figure which shows the state of a wafer stage when the exposure of the step and scan system is performed with respect to a wafer. It is a figure which shows the state of a wafer stage and the measurement stage at the time of unloading of a wafer. It is a figure which shows the state of a wafer stage and the measurement stage at the time of loading of a wafer. It is a figure which shows the state of a wafer stage and a measurement stage, and arrangement | positioning of an encoder head at the time of the switching from the drive (position control) of the wafer stage by an interferometer to the drive of the wafer stage by an encoder. It is a figure for demonstrating the state of the wafer stage and measurement stage at the time of wafer alignment. It is a top view which shows the modification of arrangement | positioning of an encoder head (X head, Y head).

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to FIGS.

  FIG. 1 schematically shows a configuration of an exposure apparatus 100 according to an embodiment. The exposure apparatus 100 is a step-and-scan projection exposure apparatus, 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 direction parallel to the optical axis AX of the projection optical system PL is a Z-axis direction, and a reticle in a plane perpendicular to the Z-axis direction. The direction in which the wafer is relatively scanned is the Y-axis direction, the direction orthogonal to the Z-axis and the Y-axis is the X-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are θx, θy, And the θz direction will be described.

  The exposure apparatus 100 includes an illumination system 10, a reticle stage RST, a projection unit PU, a stage apparatus 50 having a wafer stage WST and a measurement stage MST, a control system for these, and the like. In FIG. 1, wafer W is placed on wafer stage WST.

  The illumination system 10 includes, for example, a light source, an illumination uniformizing optical system having an optical integrator, and a reticle blind (both not shown) as disclosed in, for example, US Patent Application Publication No. 2003/0025890. And an 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, for example, ArF excimer laser light (wavelength 193 nm) is used as the illumination light IL.

  On reticle stage RST, reticle R having a circuit pattern or the like formed on its pattern surface (lower surface in FIG. 1) is fixed, for example, by vacuum suction. 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. 7) including a linear motor, for example, and also in the scanning direction (left and right direction in FIG. 1). In the Y-axis direction) at a predetermined scanning speed.

  Position information in the XY plane of reticle stage RST (including information on the position in the θz direction (hereinafter also referred to as θz rotation (or θz rotation amount) or yawing (or yawing amount) as appropriate)) is reticle laser interference. By a meter (hereinafter referred to as “reticle interferometer”) 116, a movable mirror 15 (actually, a Y movable mirror (or retroreflector) having a reflective surface orthogonal to the Y-axis direction and a reflective surface orthogonal to the X-axis direction) For example, with a resolution of about 0.25 nm. The measurement value of reticle interferometer 116 is sent to main controller 20 (not shown in FIG. 1, refer to FIG. 7). Instead of the movable mirror 15, a reflecting surface formed by mirror finishing on the end surface of the reticle stage RST may be used.

  Projection unit PU is arranged below reticle stage RST in FIG. The projection unit PU includes a lens barrel 40 and a projection optical system PL held in 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, double-sided telecentric and has a predetermined projection magnification (for example, 1/4, 1/5, or 1/8). For this reason, when the illumination area IAR on the reticle R is illuminated by the illumination system 10, the illumination light that has passed through the reticle R arranged so that the first surface (object surface) and the pattern surface of the projection optical system PL substantially coincide with each other. Due to 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 (projection unit PU), and the second surface (image) of the projection optical system. Formed on a region (hereinafter also referred to as an exposure region) IA that is conjugate to the illumination region IAR on the wafer W having a resist (sensitive agent) coated on the surface. Then, by synchronous driving of reticle stage RST and wafer stage WST, reticle R is moved relative to illumination area IAR (illumination light IL) in the scanning direction (Y-axis direction) and exposure area IA (illumination light IL). By moving the wafer W relative to 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 transferred to the shot area. The 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 exposure apparatus 100 of the present embodiment is provided with a local liquid immersion apparatus 8 for performing immersion type exposure. The local liquid immersion device 8 includes, for example, a liquid supply device 5, a liquid recovery device 6 (both not shown in FIG. 1, refer to FIG. 7), a liquid supply tube 31A, a liquid recovery tube 31B, a nozzle unit 32, and the like. As shown in FIG. 1, the nozzle unit 32 holds an optical element on the most image plane side (wafer W side) constituting the projection optical system PL, here a lens (hereinafter also referred to as “tip lens”) 191. It is suspended and supported by a main frame (not shown) that holds the projection unit PU so as to surround the lower end portion of the lens barrel 40. In the present embodiment, as shown in FIG. 1, the lower end surface of the nozzle unit 32 is set substantially flush with the lower end surface of the front lens 191. Further, the nozzle unit 32 is connected to the supply port and the recovery port of the liquid Lq, the lower surface on which the wafer W is disposed and provided with the recovery port, and the supply connected to the liquid supply tube 31A and the liquid recovery tube 31B, respectively. A flow path and a recovery flow path are provided.

  The liquid supply pipe 31A is connected to the liquid supply apparatus 5 (not shown in FIG. 1, see FIG. 7), and the liquid recovery pipe 31B is connected to the liquid recovery apparatus 6 (not shown in FIG. 1, see FIG. 7). Here, the liquid supply device 5 includes a tank for storing the liquid, a pressurizing pump, a temperature control device, a valve for controlling the flow rate of the liquid, and the like. The liquid recovery device 6 includes a tank for storing the recovered liquid, a suction pump, a valve for controlling the flow rate of the liquid, and the like.

  The main control device 20 (see FIG. 7) controls the liquid supply device 5 to supply the liquid Lq between the tip lens 191 and the wafer W via the liquid supply pipe 31A and to control the liquid recovery device 6. Then, the liquid Lq is recovered from between the front lens 191 and the wafer W via the liquid recovery tube 31B. At this time, main controller 20 controls liquid supply device 5 and liquid recovery device 6 so that the amount of supplied liquid Lq and the amount of recovered liquid Lq are always equal. Therefore, a fixed amount of liquid Lq (see FIG. 1) is always exchanged and held between the front lens 191 and the wafer W, thereby forming the liquid immersion region 14 (see FIGS. 2, 4 and the like). . In addition, even when a measurement stage MST described later is positioned below the projection unit PU, the liquid immersion region 14 can be similarly formed between the tip lens 191 and the measurement table.

  In this embodiment, pure water that transmits ArF excimer laser light (light having a wavelength of 193 nm) (hereinafter, simply referred to as “water” unless otherwise required) is used as the liquid. Note that the refractive index n of water with respect to ArF excimer laser light is approximately 1.44, and the wavelength of the illumination light IL is shortened to 193 nm × 1 / n = about 134 nm in water.

  As shown in FIG. 1, the stage apparatus 50 includes a wafer stage WST and a measurement stage MST disposed on the base board 12, and a measurement system 200 that measures positional information of these two stages WST and MST (see FIG. 7). , And a stage drive system 124 (see FIG. 7) for driving the two stages WST and MST. As shown in FIG. 7, the measurement system 200 includes an interferometer system 118, an encoder system 150, a surface position measurement system 180, and the like.

  Wafer stage WST and measurement stage MST are supported on base board 12 via a gap (gap) of about several μm by a non-contact bearing (not shown) fixed to each bottom surface, for example, an air bearing. . The two stages WST and MST can be independently driven in the XY plane by a stage drive system 124 (see FIG. 7) including a linear motor or the like.

  Wafer stage WST includes a stage main body 91 and a wafer table WTB mounted on stage main body 91. The wafer table WTB and the stage main body 91 are directed to the base board 12 in directions of six degrees of freedom (X, Y, Z, θx, etc.) by a drive system including a linear motor and a Z / leveling mechanism (including a voice coil motor). It can be driven to θy, θz).

  At the center of the upper surface of wafer table WTB, a wafer holder (not shown) for holding wafer W by vacuum suction or the like is provided. As shown in FIG. 2, a circular opening that is slightly larger than the wafer holder is formed in the center outside the wafer holder (wafer mounting area), and has a rectangular outer shape (contour) (liquid repellent). Plate) 28 is provided. The surface of the plate 28 is subjected to a liquid repellency treatment with respect to the liquid Lq. The plate 28 is installed so that the entire surface (or part) of the plate 28 is flush with the surface of the wafer W.

  The plate 28 is located at the center in the X-axis direction of the wafer table WTB, and has a first liquid repellent area 28a having a rectangular outer shape (contour) in which the circular opening is formed at the center, and the first liquid repellent area. The wafer table WTB has a pair of rectangular second liquid repellent regions 28b positioned at the + X side end and the −X side end of the wafer table WTB with the 28a interposed in the X-axis direction. In the present embodiment, since water is used as the liquid Lq as described above, the first and second liquid repellent regions 28a and 28b are also referred to as first and second water repellent plates 28a and 28b, respectively.

  A measurement plate 30 is provided in the vicinity of the + Y side end of the first water repellent plate 28a. The measurement plate 30 has a reference mark FM formed in the center, and a pair of aerial image measurement slit patterns (slit-shaped measurement patterns) SL formed on both sides of the reference mark FM in the X-axis direction. Corresponding to each aerial image measurement slit pattern SL, the illumination light IL transmitted therethrough is transmitted to the outside of wafer stage WST, specifically, the above-described light receiving system (non-detection system) provided on measurement table MTB (and stage body 92). A light transmission system (not shown) leading to the illustration is provided on wafer stage WST.

On the pair of second water repellent plates 28b, scales used in an encoder system described later are formed. More specifically, scales 39 ₁ and 39 ₂ are formed on the pair of second water repellent plates 28b, respectively. Each of the scales 39 ₁ and 39 ₂ is constituted by a reflective two-dimensional diffraction grating in which, for example, a diffraction grating having a periodic direction in the Y-axis direction and a diffraction grating having a periodic direction in the X-axis direction are combined. The pitch of the lattice lines of the two-dimensional diffraction grating is set to 1 μm, for example, in both the Y-axis direction and the X-axis direction. In FIG. 2, for the convenience of illustration, the pitch of the grating is shown larger than the actual pitch. The same applies to the other drawings.

  In order to protect the diffraction grating, it is also effective to cover with a glass plate having water repellency, for example, a low thermal expansion coefficient. Here, as the glass plate, a glass plate having the same thickness as the wafer, for example, a thickness of 1 mm can be used, and the wafer table is such that the surface of the glass plate is the same height (same surface) as the wafer surface. Installed on top of WTB.

  A positioning pattern (not shown) for determining a relative position between an encoder head and a scale, which will be described later, is provided near the end of the scale of each second water repellent plate 28b. This positioning pattern can be constituted by, for example, a grid line having a reflectance different from that of the scale.

  On the −Y end surface and −X end surface of wafer table WTB, as shown in FIGS. 2 and 4, etc., reflecting surface 17a and reflecting surface 17b used in an interferometer system to be described later are formed.

  As shown in FIG. 1, the measurement stage MST includes a stage main body 92 that is driven in an XY plane by a linear motor (not shown) and the like, and a measurement table MTB mounted on the stage main body 92. The measurement stage MST is configured to be driven in at least three degrees of freedom (X, Y, θz) with respect to the base board 12 by a drive system (not shown).

  In FIG. 7, a stage drive system 124 is shown including a drive system for wafer stage WST and a drive system for measurement stage MST.

  Various measurement members are provided on the measurement table MTB (and the stage main body 92). As the measurement member, for example, as shown in FIG. 4, an illuminance unevenness sensor 94, an aerial image measuring device 96, a wavefront aberration measuring device 98, an illuminance monitor (not shown), and the like are provided. Further, the stage main body 92 is provided with a pair of light receiving systems (not shown) in an arrangement facing the above pair of light sending systems (not shown). In the present embodiment, each aerial image measurement slit pattern SL of measurement plate 30 on wafer stage WST is measured in a state where wafer stage WST and measurement stage MST are close to each other within a predetermined distance in the Y-axis direction (including a contact state). A pair of aerial image measuring devices 45A and 45B (see FIG. 7) that guides the transmitted illumination light IL by each light transmission system (not shown) and receives light by a light receiving element of each light receiving system (not shown) in the measurement stage MST. ) Is configured.

  As shown in FIG. 4, a fiducial bar (hereinafter abbreviated as “FD bar”) 46 extends in the X-axis direction on the −Y side end surface of the measurement table MTB. The FD bar 46 is kinematically supported on the measurement stage MST by a full kinematic mount structure. Since the FD bar 46 is a prototype (measurement standard), an optical glass ceramic having a low thermal expansion coefficient, for example, Zerodure (trade name) manufactured by Schott is used as the material. Reference gratings (for example, diffraction gratings) 52 having a periodic direction in the Y-axis direction are formed in the vicinity of one end and the other end in the longitudinal direction of the FD bar 46 in a symmetrical arrangement with respect to the center line. . A plurality of reference marks M are formed on the upper surface of the FD bar 46. As each reference mark M, a two-dimensional mark having a size detectable by a primary alignment system and a secondary alignment system described later is used. The surface of the FD bar 46 and the surface of the measurement table MTB are also covered with a liquid repellent film (water repellent film).

  A reflection surface 19a and a reflection surface 19b similar to the wafer table WTB are formed on the + Y side end surface and the −X side end surface of the measurement table MTB (see FIG. 4).

In the exposure apparatus 100 of the present embodiment, as shown in FIGS. 4 and 5, on the parallel straight line (hereinafter referred to as a reference axis) LV passing through the optical axis AX of the projection optical system PL − A primary alignment system AL1 having a detection center at a position separated by a predetermined distance on the Y side is provided. Primary alignment system AL1 is fixed to the lower surface of the main frame (not shown). As shown in FIG. 5, secondary alignment systems AL2 ₁ and AL2 _{2 in} which detection centers are arranged almost symmetrically with respect to the reference axis LV on one side and the other side in the X-axis direction across the primary alignment system AL1. , AL2 ₃ and AL2 ₄ are provided. The secondary alignment systems AL2 _{1 to} AL2 ₄ are fixed to the lower surface of the main frame (not shown) via a movable support member (not shown), and are driven by the drive mechanisms 60 _{1 to} 60 ₄ (see FIG. 7). The relative positions of these detection areas can be adjusted with respect to the axial direction. A straight line (reference axis) LA parallel to the X axis passing through the detection center of the primary alignment system AL1 shown in FIG. 4 and the like coincides with the optical axis of the measurement beam B6 from the interferometer 127 described later.

In the present embodiment, for example, an image processing type FIA (Field Image Alignment) system is used as each of the alignment systems AL1, AL2 _{1 to} AL2 ₄ . Imaging signals from each of the alignment systems AL1, AL2 _{1 to} AL2 ₄ are supplied to the main controller 20 via a signal processing system (not shown).

  Next, the configuration and the like of interferometer system 118 (see FIG. 7) that measures position information of wafer stage WST and measurement stage MST will be described.

As shown in FIG. 3, interferometer system 118 includes Y interferometer 16, X interferometers 126, 127, and 128, and Z interferometers 43A and 43B for measuring the position of wafer stage WST, and the position of measurement stage MST. A Y interferometer 18 for measurement and an X interferometer 130 are included. The Y interferometer 16 and the three X interferometers 126, 127, and 128 have interferometer beams (length measuring beams) B4 (B4 ₁ , B4 ₂ ) and B5 (B5 ₁ ) on the reflecting surfaces 17a and 17b of the wafer table WTB, respectively. , B5 ₂ ), B6 and B7. The Y interferometer 16 and the three X interferometers 126, 127, and 128 receive the reflected light, measure the position information of the wafer stage WST in the XY plane, and use the measured position information as the main information. This is supplied to the control device 20.

Here, for example, the X interferometer 126 passes through the optical axis AX of the projection optical system PL (in this embodiment, also coincides with the center of the exposure area IA described above) and is a straight line (reference axis LH (FIG. 4) in parallel with the X axis. The reflection surface 17b is irradiated with at least three length measuring beams parallel to the X axis including a pair of length measuring beams B5 ₁ and B5 ₂ symmetrical with respect to the above)). The Y interferometer 16 reflects at least three length measuring beams parallel to the Y axis, including a pair of length measuring beams B4 ₁ , B4 ₂ , and B3 (see FIG. 1) symmetrical with respect to the reference axis LV described above. 17a and a movable mirror 41 described later are irradiated. Thus, in this embodiment, a multi-axis interferometer having a plurality of measurement axes is used as each interferometer except for a part (for example, the interferometer 128). Therefore, main controller 20 determines the position in the θx direction (hereinafter referred to as “X” and “Y”) of wafer table WTB (wafer stage WST) based on the measurement results of Y interferometer 16 and X interferometer 126 or 127. , Θx rotation (or θx rotation amount), or pitching (or pitching amount) as appropriate, position in the θy direction (hereinafter, as appropriate, θy rotation (or θy rotation amount), or rolling (or rolling amount). ) And θz rotation (ie yaw amount) can also be calculated.

  As shown in FIG. 1, a movable mirror 41 having a concave reflecting surface is attached to the side surface on the −Y side of the stage main body 91. As can be seen from FIG. 2, the movable mirror 41 is set to have a length in the X-axis direction that is longer than the reflection surface 17a of the wafer table WTB.

  A pair of Z interferometers 43A and 43B are provided facing the movable mirror 41 (see FIGS. 1 and 5). The Z interferometers 43A and 43B irradiate two length measuring beams B1 and B2 to the fixed mirrors 47A and 47B fixed to, for example, a main frame (not shown) that supports the projection unit PU via the movable mirror 41, respectively. . And each reflected light is received and the optical path length of length measuring beam B1, B2 is measured. Based on the result, main controller 20 calculates the position of wafer stage WST in the four degrees of freedom (Y, Z, θy, θz) direction.

  In the present embodiment, position information (including θz rotation (ie, yawing amount)) in the XY plane of wafer stage WST (wafer table WTB) is mainly measured using an encoder system described later. Interferometer system 118 is used when wafer stage WST is located outside the measurement area of the encoder system (for example, in the vicinity of unloading position UP or loading position LP shown in FIG. 4). Further, it is used as an auxiliary when correcting (calibrating) long-term fluctuations in the measurement results of the encoder system (for example, due to deformation of the scale over time) or for backup when the output of the encoder system is abnormal. Of course, the position of wafer stage WST (wafer table WTB ') may be controlled by using interferometer system 118 and the encoder system together.

  As shown in FIG. 3, the Y interferometer 18 and the X interferometer 130 of the interferometer system 118 irradiate the reflection surfaces 19a and 19b of the measurement table MTB with interferometer beams (measurement beams), respectively. By receiving the reflected light, position information of the measurement stage MST (for example, including at least the position in the X-axis and Y-axis directions and the position in the θz direction) is measured, and the measurement result is supplied to the main controller 20. To do. Details of the configuration of the interferometer system 118 are disclosed in, for example, US Patent Application Publication No. 2008/0088843.

  Next, the configuration and the like of encoder system 150 (see FIG. 7) that measures position information (including rotation information in the θz direction) of wafer stage WST in the XY plane will be described. The main configuration of the encoder system 150 is disclosed in, for example, US Patent Application Publication No. 2008/0088843.

In the exposure apparatus 100, as shown in FIG. 4, a pair of head portions 62A and 62C are disposed on the + X side and the −X side of the projection unit PU (nozzle unit 32), respectively. In addition, head portions 62E and 62F are provided on the −Y side of each of the head portions 62C and 62A and at substantially the same Y position as the alignment systems AL1, AL2 _{1 to} AL2 ₄ . As will be described later, each of the head portions 62A, 62C, 62E, and 62F includes a plurality of heads, and these heads are suspended from a main frame (not shown) that holds the projection unit PU via a support member. It is fixed with. In FIG. 4, symbol UP indicates an unloading position at which a wafer on wafer stage WST is unloaded, and symbol LP indicates a loading position at which a new wafer is loaded on wafer stage WST. Show.

Head portion 62A, 62C is provided as the respective four two-axis head 65 _{1-65 4} 64 _{1-64 4} shown in FIG. Inside the housings of the biaxial heads 65 _{1 to} 65 ₄ are X heads 65X _{1 to} 65X ₄ whose measurement direction is the X-axis direction and Y heads 65Y _{1 to} 65Y ₄ whose measurement direction is the Y-axis direction. Contained. Similarly, X heads 64X _{1 to} 64X ₄ and Y heads 64Y _{1 to} 64Y ₄ are accommodated in the housings of the biaxial heads 64 ₁ to 64 ₄ . X heads 65X _{1 to} 65X ₄ , 64X _{1 to} 64X ₄ (more precisely, irradiation points on the scales 39 ₁ and 39 _{2 of the} measurement beams emitted by the X heads 65X _{1 to} 65X ₄ and 64X _{1 to} 64X ₄ ) Arranged on the reference axis LH at a predetermined interval WD (see FIG. 4). Y heads 65Y _{1 to} 65Y ₄ , 64Y _{1 to} 64Y ₄ (more precisely, irradiation points on the scales 39 ₁ and 39 _{2 of the} measurement beams emitted by the Y heads 65Y _{1 to} 65Y ₄ and 64Y _{1 to} 64Y ₄ ) Are arranged at the same X position as the corresponding X heads 65X _{1 to} 65X ₄ , 64X _{1 to} 64X ₄ on a straight line LH ₁ that is parallel to the reference axis LH and spaced a predetermined distance from the reference axis LH to the −Y side. Has been. In the following, X heads 65X _{1 to} 65X ₄ , 64X _{1 to} 64X ₄ , and Y heads 65Y _{1 to} 65Y ₄ , 64Y _{1 to} 64Y ₄ are respectively replaced with X heads 65X, 64X, and Y heads 65Y as necessary. , 64Y.

Here, as each of the X heads 65X and 64X and the Y heads 65Y and 64Y, for example, a diffraction interference type encoder head disclosed in US Patent Application Publication No. 2008/0088843 is used. . In this type of encoder head, two measurement beams are irradiated onto the corresponding scale 39 ₁ or 39 ₂ , and the return light (diffracted light) from the two-dimensional grating on the scale of each measurement beam is combined into one interference light. The light is received and the intensity of the interference light is measured using a photodetector. Based on the intensity change of the interference light, the displacement in the measurement direction of the scale (period direction of the diffraction grating) is measured.

The head units 62A and 62C are multi-lens (four eyes here) X linear encoders that measure the position (X position) in the X-axis direction of wafer stage WST (wafer table WTB) using scales 39 ₁ and 39 _2. The multi-lens (four eyes here) Y linear encoders 70Ay and 70Cy (see FIG. 7) that measure the positions (Y position) in the Y-axis direction are configured. These X linear encoder and Y linear encoder constitute multi-lens (four eyes in this case) two-dimensional (2D) encoders 70A and 70C that measure the X and Y positions of wafer stage WST (wafer table WTB). (See FIG. 7).

  In the following, the X linear encoder is abbreviated as “X encoder” or “encoder” as appropriate. Similarly, the Y linear encoder is abbreviated as “Y encoder” or “encoder” as appropriate. Similarly, the 2D encoder is abbreviated as an encoder as appropriate.

Here, the four X heads 65X and 64X (more precisely, the irradiation points on the scale of the measurement beam emitted by the X heads 65X and 64X) and the four Y heads 65Y and 64Y (more from the head units 62A and 62C). Precisely, the interval WD in the X-axis direction between the irradiation points on the scale of the measurement beams emitted by the Y heads 65Y and 64Y is narrower (eg, 82 mm) than the width (eg, 102 mm) of the scales 39 ₁ and 39 _{2 in} the X-axis direction. Is set). Accordingly, at the time of exposure, at least one of the four X heads 65X, 64X, and Y heads 65Y and 64Y always faces the corresponding scales 39 ₁ and 39 ₂ (the measurement beam is changed). Irradiation). For example, in one state during the exposure operation shown in FIG. 9, the X head 65X ₃ and the Y head 65Y ₃ face the scale 39 ₁ , and the X head 64X ₃ and the Y head 64Y ₃ face the scale 39 ₂ (irradiate the measurement beam). To do). Here, the width of the scale refers to the width of the diffraction grating (or its formation region), more precisely the range in which the position can be measured by the head.

Head portion 62F, 62E, as shown in FIG. 5, a respective three biaxial head 68 _{1-68 3} 67 _{1-67 3.} Inside the two-axis head 68 _{1-68 3} housing, 2 similarly to the axle head 65 _{1-65 4} etc., the X head 68X ₁ ~68X _3, is accommodated and Y head 68Y ₁ ~68Y ₃ Yes. Similarly, X heads 67X _{1 to} 67X ₃ and Y heads 67Y _{1 to} 67Y ₃ are accommodated in the housings of the biaxial heads 67 _{1 to} 67 ₃ .

The X heads 68X _{1 to} 68X ₃ , 67X _{1 to} 67X ₃ (more precisely, irradiation points on the scales 39 ₁ and 39 _{2 of the} measurement beams emitted by 68X _{1 to} 68X ₃ and 67X _{1 to} 67X ₃ ) Arranged at a predetermined interval WD (see FIG. 4) along the reference axis LA. The Y heads 68Y _{1 to} 68Y ₃ , 67Y _{1 to} 67Y ₃ (more precisely, the irradiation points on the scales 39 ₁ and 39 _{2 of the} measurement beams emitted by 68Y _{1 to} 68Y ₃ and 67Y _{1 to} 67Y ₃ ) are the reference axes. on a straight line LA ₁ spaced apart on the -Y side from it and the reference axis LA is parallel to the LA, the same X positions as the corresponding X head _{68X 1 ~68X 3, 67X 1 ~67X} 3, are arranged. In the following, optionally, biaxially head _{68 1 ~68 3, 67 1 ~67} 3, X head _{68X 1 ~68X 3, 67X 1 ~67X} 3, and Y heads 68Y ₁ ~68Y _3, 67Y ₁ ~67Y ₃ is also expressed as biaxial heads 68 and 67, X heads 68X and 67X, and Y heads 68Y and 67Y, respectively. Here, as each of the X heads 68X and 67X and the Y heads 68Y and 67Y, the diffraction interference type encoder head disclosed in the above-mentioned US Patent Application Publication No. 2008/0088843 is used. .

The heads 62F and 62E are multi-lens (three eyes here) X linear encoders that measure the position (X position) in the X-axis direction of wafer stage WST (wafer table WTB) using scales 39 ₁ and 39 _2. The multi-lens (three eyes here) Y linear encoders 70Fy and 70Ey (see FIG. 7) that measure the positions (Y positions) in the Y-axis direction are configured. These X linear encoder and Y linear encoder constitute multi-lens (four eyes here) two-dimensional (2D) encoders 70F and 70E that measure the X and Y positions of wafer stage WST (wafer table WTB). (See Fig. 7)

Here, the three X heads 68X and 67X (more precisely, the irradiation points on the scale of the measurement beams emitted by the X heads 68X and 67X) and the three Y heads 68Y and 67Y (more Precisely, the distance WD in the X-axis direction between the irradiation points on the scale of measurement beams emitted from the Y heads 68Y and 67Y is set slightly smaller than the width of the scales 39 ₁ and 39 _{2 in} the X-axis direction. Accordingly, at the time of alignment measurement, at least one of the three X heads 68X, 67X, Y heads 68Y, 67Y faces the corresponding scale 39 ₁ , 39 ₂ (irradiates the measurement beam). . For example, in one state during alignment measurement shown in FIG. 13, the X head 68X ₂ and the Y head 68Y ₂ face the scale 39 ₁ , and the X head 67X ₂ and the Y head 67Y ₂ face the scale 39 ₂ (irradiate the measurement beam). To do).

The measured values of the encoders 70Ax, 70Ay, 70Cx, and 70Cy (X and Y measured values of the encoders 70A and 70C) are supplied to the main controller 20. Main controller 20 uses these measurement values to calculate position (X, Y, θz) of wafer stage WST in the XY plane. Here, the measured value of the encoder 70Ax or 70Cx (that is, the X measured value of one of the encoders 70A and 70C), the Y measured value of the encoders 70A and 70Y, that is, the measured values of the encoders 70Ay and 70Cy (respectively C _X , C _Y1 ,. C _Y2 ) depends on the position (X, Y, θz) of wafer stage WST as follows.

C _X = (p _X −X) cos θz + (q _X −Y) sin θz, (1a)
C _Y1 = − (p _Y1 −X) sin θz + (q _Y1 −Y) cos θz, (1b)
C _Y2 = − (p _Y2 −X) sin θz + (q _Y2 −Y) cos θz. ... (1c)
However, (p _X , q _X ), (p _{Y 1} , q _{Y 1} ), (p _{Y 2} , q _{Y 2} ) are respectively the X and Y installation positions (more precisely, X heads 65 X, 64 X, Y heads 65 Y, 64 _Y ). X, Y position of the measurement beam irradiation point). Therefore, main controller 20 substitutes three measurement values C _X , C _Y1 , and C _Y2 into simultaneous equations (1a) to (1c) and solves them to thereby determine the position of wafer stage WST in the XY plane. (X, Y, θz) is calculated.

The measured values of the encoders 70Ex, 70Ey, 70Fx, 70Fy (X and Y measured values of the encoders 70E, 70F) are also supplied to the main control device 20. Main controller 20 uses these measurement values to calculate position (X, Y, θz) of wafer stage WST in the XY plane. The main control device 20 obtains the measured values of the encoders 70Ex (or 70Fx), 70Ey, and 70Fy (that is, the X measured values of the encoder 70E or 70F and the Y measured values of the encoders 70E and 70F) from the simultaneous equations (1a) to (1a) to The position (X, Y, θz) in the XY plane of wafer stage WST is calculated by substituting into C _X , C _Y1 , and C _Y2 in (1c) and solving the simultaneous equations.

  Main controller 20 drives (position controls) wafer stage WST based on the above calculation result.

In the present embodiment, the Y heads 67Y ₃ and 68Y ₁ of the biaxial heads 67 ₃ and 68 ₁ that are adjacent to the secondary alignment systems AL2 ₁ and AL2 ₄ in the X-axis direction are used when measuring the baseline of the secondary alignment system. The Y position of the FD bar 46 is measured at the position of each reference grating 52 by the Y heads 67Y ₃ and 68Y _{1 that} face the pair of reference gratings 52 of the FD bar 46, respectively. Is done. In the following, encoders composed of Y heads 67Y ₃ and 68Y ₁ facing the pair of reference gratings 52 are respectively Y linear encoders (hereinafter also abbreviated as “Y encoder” or “encoder” as appropriate) 70G and 70H (FIG. 10). See). The Y encoders 70G and 70H are configured as Y linear encoders because a part of the Y heads 67Y ₃ and 68Y ₁ constituting the encoders 70F and 70E are opposed to the pair of reference gratings 52. It is what you call. In the following, for the sake of convenience, description will be made assuming that Y encoders 70G and 70H exist in addition to XY encoders 70F and 70E.

  Each encoder mentioned above supplies the measured value to the main controller 20. Main controller 20 controls the position (including the position in the θz direction (yawing)) of wafer table WTB in the XY plane based on the measurement values of encoders 70A and 70C or 70E and 70F, and Y encoder 70G. And the position (yawing) of the FD bar 46 (measurement stage MST) in the θz direction based on the measured values of 70H.

Further, main controller 20 drives X stage 65X, 64X for measuring the X position and Y position of wafer stage WST when driving wafer stage WST in the X-axis direction as shown by the white arrow in FIG. and Y head 65Y, the 64Y, as indicated by arrows e ₁ in FIG. 8, sequentially switching adjacent X heads 65X, 64X and Y head 65Y, the 64Y. For example, switching from the X head 64X ₂ to the X head 64X ₃ (and from the X head 65X ₂ to the X head 65X ₃ ). That is, in the second embodiment, in order to smoothly switch (connect) the head X head and the Y head, as described above, the distance WD between the adjacent X head and Y head included in the head portions 62A and 62C. Is set to be narrower than the width of the scales 39 ₁ and 39 _{2 in} the X-axis direction.

  Furthermore, in the exposure apparatus 100 of the present embodiment, as shown in FIGS. 4 and 6, a multipoint focal position detection system (hereinafter referred to as “multipoint AF system”) including an irradiation system 90a and a light receiving system 90b. ) Is provided. As the multipoint AF system, the same configuration (oblique incidence method) as that disclosed in, for example, US Pat. No. 5,448,332 is adopted. In the present embodiment, as an example, the irradiation system 90a is disposed on the + Y side of the −X end portion of the head portion 62E described above, and light is received on the + Y side of the + X end portion of the head portion 62F while facing this. A system 90b is arranged. The multipoint AF system (90a, 90b) is fixed to the lower surface of the main frame that holds the projection unit PU.

  In FIG. 4 and FIG. 6, a plurality of detection points irradiated with the detection beam are not shown individually, but as elongated detection areas (beam areas) AF extending in the X-axis direction between the irradiation system 90a and the light receiving system 90b. It is shown. Since the detection area AF is set to have a length in the X-axis direction that is approximately the same as the diameter of the wafer W, the wafer W is scanned almost in the Y-axis direction once in the Z-axis direction. Position information (surface position information) can be measured.

  As shown in FIG. 6, each pair of pairs constituting a part of the surface position measurement system 180 is arranged in the vicinity of both ends of the detection area AF of the multipoint AF system (90a, 90b) in a symmetrical arrangement with respect to the reference axis LV. Heads (hereinafter abbreviated as “Z heads”) 72a, 72b, 72c, 72d of the Z position measuring sensor are provided. These Z heads 72a to 72d are fixed to the lower surface of a main frame (not shown).

As the Z heads 72a to 72d, for example, a head of an optical displacement sensor similar to an optical pickup used in a CD drive device or the like is used. Z heads 72a to 72d irradiate wafer table WTB with a measurement beam from above, receive the reflected light, and measure the surface position of wafer table WTB at the irradiation point. In the present embodiment, a configuration is adopted in which the measurement beam of the Z head is reflected by the reflection type diffraction grating constituting the scales 39 ₁ and 39 ₂ described above.

Further, head unit 62A, 62C mentioned above is provided as the respective four Z heads 76 ₁ to 76 _4, 74 ₁ to 74 ₄ shown in FIG. Here, the Z heads 76 _{1 to} 76 ₄ , 74 ₁ to 74 ₄ are parallel to the reference axis LH and correspond to the X heads 65X _{1 to} 65X ₄ on the straight line LH ₂ spaced from the reference axis LH to the + Y side. , 64X _{1 to} 64X ₄ are arranged at the same X position. Incidentally, as each Z head 76 _{1-76 4} 74 _{1-74 4,} the head of the same optical displacement sensor as described above for Z head 72a~72d is employed. In the following, optionally, Z heads 76 ₁ to 76 _4, 74 ₁ to 74 _4, referred both Z heads 76 and 74.

Z heads 72a to 72d, 74 to _{72d 4,} 76 ₁ to 76 _4, as shown in FIG. 7, via the signal processing and selection device 170 is connected to the main controller 20, the main controller 20 It is, Z head 72a~72d via signal processing and selection device 170, _{72d 4,} 76 ₁ to 76 ₄ select any Z head from the operating state, Z head as its operating state Is received via the signal processing / selection device 170. In the present embodiment, the position information in the Z axis direction of wafer stage WST and the tilt direction with respect to the XY plane includes Z heads 72a to 72d, 74 ₁ to 74 ₄ , 76 _{1 to} 76 ₄ and signal processing / selection device 170. A surface position measurement system 180 is measured.

  In the present embodiment, main controller 20 uses surface position measurement system 180 (see FIG. 7), in an effective stroke area of wafer stage WST, that is, in an area where wafer stage WST moves for exposure and alignment measurement. The position coordinates in the direction of two degrees of freedom (Z, θy) are measured.

At the time of exposure, main controller 20 uses a measured value of at least one of Z heads 76 _j and 74 _i (j and i are any one of 1 to 4) to use a reference point (wafer on the surface of wafer table WTB). in table top and the intersection between the optical axis AX of WTB), and calculates the height _{Z 0} and rolling θy of the wafer stage WST. In one state during the exposure operation shown in FIG. 8, the measured values of the Z heads 76 ₃ and 74 ₃ facing the scales 39 ₁ and 39 ₂ are used. Here, the measured values (represented as Z ₁ and Z ₂ , respectively) of Z heads 76 _j and 74 _i (j and i are any one of 1 to 4) are (Z ₀ , θx, θy) of wafer stage WST. It depends on the position as follows.

Z ₁ = −tan θy · p ₁ + tan θx · q ₁ + Z ₀ . ... (2a)
Z ₂ = −tan θy · p ₂ + tan θx · q ₂ + Z ₀ , (2b)
However, it is assumed that the upper surface of wafer table WTB including the scale surface is an ideal plane. (P ₁ , q ₁ ) and (p ₂ , q ₂ ) are the X and Y installation positions of the Z heads 76 _j and 74 _i (more precisely, the X and Y positions of the irradiation point of the measurement beam), respectively. is there. From the equations (2a) and (2b), the following equations (3a) and (3b) are derived.

Z ₀ = [Z ₁ + Z ₂ −tan θx · (q ₁ + q ₂ )] / 2, (3a)
tan θy = [Z ₁ −Z ₂ −tan θx · (q ₁ −q ₂ )] / (p ₁ −p ₂ ). ... (3b)
Therefore, main controller 20 calculates height Z ₀ of wafer stage WST and rolling θy from equations (3a) and (3b) using measured values Z ₁ and Z ₂ of Z heads 76 _j and 74 _i. To do. However, the pitching θx uses a measurement result of another sensor system (interferometer system 118 in the present embodiment).

At the time of focus mapping, which will be described later, main controller 20 uses the measurement values (represented as Za, Zb, Zc, and Zd, respectively) of four Z heads 72a to 72d facing scales 39 ₁ and 39 ₂ , to The height Z ₀ and rolling θy of wafer table WTB at the center (X, Y) = (Ox ′, Oy ′) of the plurality of detection points of AF system (90a, 90b) are calculated as follows.

Z ₀ = (Za + Zb + Zc + Zd) / 4, (4a)
tanθy = - (Za + Zb- Zc-Zd) / (p a + p b -p c -p d). ... (4b)
Here, (p _a , q _a ), (p _b , q _b ), (p _c , q _c ), and (p _d , q _d ) are the X and Y installation positions (more accurate) of the Z heads 72a to 72d, respectively. (X, Y position of the irradiation point of the measurement beam). _{However, p a = p b, p} c = p d, q a = q c, q b = q d, (p a + p c) / 2 = (p b + p d) / 2 = Ox ', (q a + Q _b ) / 2 = (q _c + q _d ) / 2 = Oy ′. As in the previous case, the pitching θx uses the measurement result of another sensor system (interferometer system 118 in the present embodiment).

  FIG. 7 shows the main configuration of the control system of the exposure apparatus 100. This control system is mainly configured of a main control device 20 composed of a microcomputer (or a workstation) for overall control of the entire apparatus. In FIG. 7, various sensors provided on the measurement stage MST such as the illuminance unevenness sensor 94, the aerial image measuring device 96, and the wavefront aberration measuring device 98 described above are collectively shown as a sensor group 99.

  In the exposure apparatus of the present embodiment configured as described above, in the same manner as in the second embodiment of US Patent Application Publication No. 2009/0268578, a general process using wafer stage WST is generally performed according to the following procedure. The process of the sequence is executed by the main controller 20. During the following operations, the main controller 20 controls the opening and closing of the valves of the liquid supply device 5 and the liquid recovery device 6 of the local liquid immersion device 8 as described above, and the leading end lens of the projection optical system PL. Directly below 191 is always filled with water. However, in the following, in order to make the explanation easy to understand, explanation regarding the control of the liquid supply device 5 and the liquid recovery device 6 is omitted. Further, the following description of the operation will be made with reference to a number of drawings, and the same members may or may not be labeled with the same members for each drawing. In other words, although the reference numerals described in the drawings are different, the drawings have the same configuration regardless of the presence or absence of the reference numerals. The same applies to each drawing used in the description so far.

  FIG. 9 shows a state in which step-and-scan exposure is performed on wafer W placed on wafer stage WST. This exposure is a shot that moves wafer stage WST to a scan start position (acceleration start position) for exposure of each shot area on wafer W based on the result of wafer alignment (for example, EGA) performed before the start. It is carried out by repeating the inter-movement and the scanning exposure for transferring the pattern formed on the reticle R to each shot area by the scanning exposure method. Further, the exposure is performed in order from the shot area located on the −Y side on the wafer W to the shot area located on the + Y side.

During the exposure operation described above, main controller 20 causes wafer stage WST (wafer table WTB) to move in the XY plane (including rotation in the θz direction) to X head 65X that faces scales 39 ₁ and 39 ₂ , respectively. And Y head 65Y, and the control is based on the measurement values of the two encoders 70A and 70C configured by the X head 64X and Y head 65Y. During the exposure operation described above, the main controller 20 determines the position of the wafer stage WST in the Z-axis direction (Z position) and the position in the θy direction (rolling) by the Z heads 76 and 74 of the surface position measurement system 180. The θx rotation (pitching) is managed based on the measurement value of the Y interferometer 16 described above. The position of the wafer stage WST (wafer table WTB) during exposure in the Z-axis direction, θy direction, and θx direction (focus / leveling control of the wafer W) is controlled by the main controller 20 in advance. This is performed based on the measurement result of the position information and the measurement result of the corresponding encoder system 150 and / or interferometer system 118.

  When the wafer stage WST moves in the X-axis direction during the above-described step-and-scan exposure operation, the above-described head switching is performed along with the movement. As described above, main controller 20 executes driving (position control) of the wafer stage by appropriately switching the encoder to be used according to the position coordinates of wafer stage WST.

  Note that the position (X, Y, Z, θx, θy, θz) measurement of wafer stage WST using interferometer system 118 is always performed independently of the position measurement of wafer stage WST using the encoder system described above. It has been broken. For example, one of X interferometers 126, 127, and 128 is used according to the Y position of wafer stage WST. For example, during exposure, an X interferometer 126 is used as an auxiliary, as shown in FIG.

  When exposure of wafer W is completed, main controller 20 drives wafer stage WST toward unloading position UP. At that time, wafer stage WST and measurement stage MST, which are separated from each other during exposure, are brought into contact with each other with a separation distance of about 300 μm, for example, and shift to a scram state. Here, the −Y side end surface of the FD bar 46 on the measurement table MTB and the + Y side end surface of the wafer table WTB come into contact with or approach each other. By maintaining the scram state and moving the two stages WST and MST in the −Y direction, the liquid immersion region 14 formed under the projection unit PU moves on the measurement stage MST.

  When the wafer stage WST further moves in the −Y direction after shifting to the above-described scrum state and deviates from the effective stroke area (area where the wafer stage WST moves during exposure and wafer alignment), all of the encoder system 150 are configured. The head deviates from the corresponding scale on wafer table WTB. This makes it impossible to drive (position control) wafer stage WST based on the measurement result of encoder system 150. Immediately before that, main controller 20 switches to driving (position control) of wafer stage WST based on the measurement result of interferometer system 118. Here, among the three X interferometers 126, 127, and 128, the X interferometer 128 is used.

  Thereafter, as shown in FIG. 10, wafer stage WST releases the scrum state with measurement stage MST and moves to unloading position UP. After the movement, main controller 20 unloads wafer W on wafer table WTB. Then, as shown in FIG. 11, wafer stage WST is driven in the + X direction to move to loading position LP, and next wafer W is loaded onto wafer table WTB.

In parallel with these operations, main controller 20 adjusts the position of FD bar 46 supported by measurement stage MST in the XY plane, baseline measurement of _four secondary alignment systems AL2 _{1 to} AL2 ₄ , Execute Sec-BCHK (secondary baseline check). Here, in order to measure the position (rotation) information of the FD bar 46 in the θz direction, the Y heads 67Y ₃ and 68Y ₂ facing the pair of reference gratings 52, that is, the aforementioned Y encoders 70G and 70H are used.

Next, main controller 20 drives wafer stage WST, positions reference mark FM on measurement plate 30 within the detection field of primary alignment system AL1, as shown in FIG. 12, and provides four secondary alignment systems. The reference position of the baseline measurement of AL2 _{1 to} AL2 ₄ is obtained.

At this time, as shown in FIG. 12, the two X heads 68X ₃ and 67X ₂ and the two Y heads 68Y ₃ and 67Y ₂ face the scales 39 ₁ and 39 ₂ , respectively. Therefore, main controller 20 switches from interferometer system 118 to driving (position control) of wafer stage WST using encoder system 150 (encoders 70E and 70F). The interferometer system 118 is again used auxiliary. Of the three X interferometers 126, 127, and 128, the X interferometer 127 is used.

Thereafter, main controller 20 performs wafer alignment (EGA) using primary alignment system AL1 and secondary alignment systems AL2 _{1 to} AL2 ₄ (see the star mark in FIG. 13).

  In the present embodiment, wafer stage WST and measurement stage MST are in the scrum state before the wafer alignment shown in FIG. 13 is started. Main controller 20 drives the two stages WST and MST in the + Y direction while maintaining the scrum state. Thereafter, the water in the immersion area 14 moves from the measurement table MTB to the wafer table WTB.

  In parallel with the wafer alignment (EGA), the main controller 20 uses the Z heads 72a to 72d and the multipoint AF system (90a, 90b) to position information (surface position information) on the surface of the wafer W in the Z-axis direction. Focus mapping to detect) is performed. Further, main controller 20 measures the intensity distribution of the projected image of the mark on the reticle with respect to the XY position of wafer table WTB using aerial image measuring devices 45A and 45B when wafer stage WST comes to a predetermined position. Execute.

  When the above operations are completed, main controller 20 releases the scrum state of the two stages WST and MST. Then, as shown in FIG. 9, step-and-scan exposure is performed to transfer a reticle pattern onto a new wafer W. Thereafter, the same operation is repeatedly executed.

As described above, according to the exposure apparatus 100 of the present embodiment, the measurement beams are irradiated from the plurality of X heads 65 and 64 to the upper surfaces (measurement surfaces) of the scales 39 ₁ and 39 _2. The point is located on a straight line in the X-axis direction that passes through the irradiation center of the illumination light IL irradiated onto the wafer on the measurement surface. Therefore, the X heads 65 and 64 can measure the position of the wafer stage WST in the X-axis direction without Abbe error. Thereby, the position controllability of wafer stage WST in the X-axis direction during exposure can be improved.

Further, the Y position of wafer stage WST is arranged symmetrically with respect to the exposure position or the exposure center (in this embodiment, coincides with optical axis AX), and is on the upper surfaces (measurement surfaces) of opposing scales 39 ₁ and 39 _2. Is measured based on the average of the measurement values of the pair of Y heads 65 and 64 that irradiate the measurement beam to the point. Therefore, since the substantial measurement axis in the Y-axis direction is on the exposure center, the position of wafer stage WST in the Y-axis direction can be measured with high accuracy without Abbe error, and as a result, highly accurate position control is possible. Is possible. Accordingly, main controller 20 uses encoders 70A and 70C to accurately acquire position information (including position information in the θz direction) of wafer stage WST during the step-and-scan exposure operation in the XY plane. It is possible to accurately measure and drive wafer stage WST based on the measurement result.

  In addition, since the scale does not have to be disposed in the + Y side end area on the upper surface of the wafer table WTB of the present embodiment, that is, the area where the liquid immersion area 14 frequently passes, the liquid remains in the area, or Even if dust adheres, there is no possibility that the measurement accuracy of the encoder system will deteriorate. Therefore, there is no possibility that the encoder system 150 is unnecessarily switched to the backup interferometer system 118. In each of the exposure area and the alignment area, the X head and the Y head (and the Z head) are arranged on a straight line parallel to the X axis. Therefore, according to the present embodiment, the layout of the encoder head is easier than the exposure apparatus disclosed as an embodiment in US Patent Application Publication No. 2008/0088843.

Further, according to the exposure apparatus 100 of the present embodiment, during the exposure, it is used for measuring the position of the wafer stage WST in the X-axis direction, the Y-axis direction, and the θz direction facing the scales 39 ₁ and 39 ₂ , respectively. Each of the four X heads and Y heads (and Z heads) respectively belonging to the head portions 62A and 62C has an interval WD between adjacent heads with respect to the X axis direction, and the width of the scales 39 ₁ and 39 _{2 in} the X axis direction. Since the desired interval taking into account (for example, 102 mm) is set to 82 mm, for example, the four X heads and Y heads (and Z heads) of the head portions 62A and 62C are connected (switching of the used head). It is possible to perform without trouble. Therefore, the encoder system 150 including the encoders 70A and 70C having the head portions 62A and 62B, respectively, can accurately measure the position of the wafer stage WST in the XY plane without being affected by air fluctuations. It becomes possible.

  Further, according to the exposure apparatus 100 of the present embodiment, based on the latest baseline obtained by the baseline measurement of the alignment system described above every time the wafer is replaced and the result of wafer alignment (EGA). The shot stage movement operation in which the wafer stage WST is moved to the scanning start position (acceleration start position) for exposure of each shot area on the wafer W, and the pattern formed on the reticle R by the scanning exposure method. By repeating the scanning exposure operation for transferring to the wafer, the pattern of the reticle R can be transferred to a plurality of shot areas on the wafer W with high accuracy (overlay accuracy). Furthermore, in the present embodiment, high-resolution exposure can be realized by immersion exposure, so that a fine pattern can be accurately transferred onto the wafer W in this respect.

  In the exposure apparatus 100 of the present embodiment, when the main controller 20 drives the wafer stage WST during exposure or the like, the measured values of the encoder system 150 (encoders 70A and 70C) and the measured values of the encoders are used. XY of wafer stage WST based on correction information for correcting the value (for example, at least one of stage position error correction information (including head error correction information), scale characteristic information and Abbe error correction information). It is desirable to control the position in the plane (including the rotation in the θz direction) with high accuracy. The various correction information is disclosed in, for example, US Patent Application Publication No. 2009/0268578.

  In the above-described embodiment, a case has been described in which three types of one-dimensional heads whose measurement directions are the X-axis direction, the Y-axis direction, and the Z-axis direction, that is, the X head, the Y head, and the Z head are used in combination. . However, instead of these three types of one-dimensional heads, for example, a three-dimensional head having all of the X-axis direction, the Y-axis direction, and the Z-axis direction as measurement directions may be used. When this three-dimensional head is used, this three-dimensional head may be arranged on the reference axis LH instead of the X heads 65X and 64X described above.

  Further, instead of the 2D head (biaxial head) in which the X head and Y head described in the above embodiment are housed in one housing, measurement beams for X direction measurement and Y direction measurement are applied to the same irradiation point. It is also possible to use a two-dimensional head having a measurement direction in the X-axis direction and the Y-axis direction. As this type of two-dimensional head, for example, a three-grating diffraction interference type 2D head disclosed in US Patent Application Publication No. 2009/0268578 can be used. This 2D head may be arranged on the reference axis LH instead of the X heads 65X and 64X described above. In this case, the Y head need not be provided.

  Further, instead of the X head and the Z head in the above embodiment, a two-dimensional head having the measurement direction in the X axis direction and the Z axis direction may be used. As this type of two-dimensional head, for example, a displacement measuring sensor head disclosed in US Pat. No. 7,561,280 can be used. This two-dimensional head may be disposed on the reference axis LH instead of the X heads 65X and 64X described above.

  In the above embodiment, the X head whose measurement direction is the X axis direction and the Y head whose measurement direction is the Y axis direction are arranged on the reference axes LH and LH1 parallel to the X axis. Instead, as shown in FIG. 14, the X head 62X and the Y head 62Y can be alternately arranged on the reference axis LH. Similarly, the X head 64X and Y head 64Y are alternately on the reference axis LH, the X head 68X and Y head 68Y are alternately on the reference axis LA, and the X head 67X and Y head 67Y are alternately on the reference axis LA. It is also possible to arrange. The encoder system with the X head and Y head arrangement shown in FIG. 14 can also measure the XY position of wafer stage WST with high accuracy without Abbe error, as in the above embodiment.

  Note that an immersion exposure apparatus disclosed in, for example, European Patent Application Publication No. 1,420,298, US Patent No. 6,952,253, or US Patent Application Publication No. 2008/0088843. In addition, the above embodiment can be applied. Further, the present embodiment is not limited to this, and the above embodiment may be applied to a dry type exposure apparatus that exposes the wafer W without using liquid (water).

  In the above-described embodiment, the case where the exposure apparatus is a step-and-scan scanning exposure apparatus has been described. However, the present invention is not limited to this, and a step-and-stitch system that combines a shot area and a shot area is used. The above-described embodiment can also be applied to a reduction projection exposure apparatus, a proximity exposure apparatus, a mirror projection aligner, or the like. Further, as disclosed in, for example, US Pat. No. 6,590,634, US Pat. No. 5,969,441, US Pat. No. 6,208,407, etc. The above embodiment can also be applied to a multi-stage type exposure apparatus provided with a stage. Further, as disclosed in, for example, International Publication No. 2005/0774014, an exposure apparatus provided with a measurement stage including a measurement member (for example, a reference mark and / or a sensor) separately from the wafer stage is also described above. The embodiment can be applied.

  Further, the projection optical system in the exposure apparatus of the above embodiment may be not only a reduction system but also any of the same magnification and enlargement systems, and the projection optical system PL may be any of a reflection system and a catadioptric system as well as a refraction system. The projected image may be either an inverted image or an erect image. In addition, the illumination area and the exposure area described above are rectangular in shape, but the shape is not limited to this, and may be, for example, an arc, a trapezoid, or a parallelogram.

The light source of the exposure apparatus of the above embodiment is not limited to the ArF excimer laser, but is a KrF excimer laser (output wavelength 248 nm), F ₂ laser (output wavelength 157 nm), Ar ₂ laser (output wavelength 126 nm), Kr ₂ laser ( It is also possible to use a pulse laser light source with an output wavelength of 146 nm, an ultrahigh pressure mercury lamp that emits a bright line such as g-line (wavelength 436 nm), i-line (wavelength 365 nm), and the like. A harmonic generator of a YAG laser or the like can also be used. In addition, as disclosed in, for example, US Pat. No. 7,023,610, a single wavelength laser beam in an infrared region or a visible region oscillated from a DFB semiconductor laser or a fiber laser is used as vacuum ultraviolet light. For example, a harmonic that is amplified by a fiber amplifier doped with erbium (or both erbium and ytterbium) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

  In the above embodiment, it is needless to say that the illumination light IL of the exposure apparatus 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, the above-described embodiment is preferably applied to an EUV exposure apparatus that uses a light source that generates EUV (Extreme Ultraviolet) light in a soft X-ray region (for example, a wavelength region of 5 to 15 nm) using a SOR or a plasma laser as a light source. be able to. In addition, the above embodiment can be applied to an exposure apparatus that uses charged particle beams such as an electron beam or an ion beam.

  In the above-described embodiment, a light transmission mask (reticle) in which a predetermined light-shielding pattern (or phase pattern / dimming pattern) is formed on a light-transmitting substrate is used. Instead of this reticle, For example, as disclosed in US Pat. No. 6,778,257, an electronic mask (variable shaping mask, which forms a transmission pattern, a reflection pattern, or a light emission pattern based on electronic data of a pattern to be exposed, as disclosed in US Pat. No. 6,778,257. For example, a non-light emitting image display element (spatial light modulator) including a DMD (Digital Micro-mirror Device) may be used.

  For example, the above-described embodiment can be applied to an exposure apparatus (lithography system) that forms line and space patterns on a wafer by forming interference fringes on the wafer.

  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 one scan exposure is performed on one wafer. The above embodiment can also be applied to an exposure apparatus that performs double exposure of shot areas almost simultaneously.

  Note that the object on which the pattern is to be formed in the above embodiment (the object to be exposed to the energy beam) is not limited to the wafer, but other objects such as a glass plate, a ceramic substrate, a film member, or a mask blank. But it ’s okay.

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing. For example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern onto a square glass plate, an organic EL, a thin film magnetic head, an image sensor ( CCDs, 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 above embodiment can also be applied to an exposure apparatus that transfers a circuit pattern.

  An electronic device such as a semiconductor element includes a step of designing a function / performance of the device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and the exposure apparatus (pattern forming apparatus) of the above-described embodiment. ) A lithography step for transferring a mask (reticle) pattern onto a wafer, a development step for developing the exposed wafer, an etching step for removing exposed members other than the portion where the resist remains by etching, and etching is completed. 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, in the lithography step, the exposure method described above is executed using the exposure apparatus of the above embodiment, and a device pattern is formed on the wafer. Therefore, a highly integrated device can be manufactured with high productivity.

  The exposure apparatus of the present invention is suitable for forming a pattern on a substrate in a lithography process for manufacturing a microdevice such as a semiconductor element (such as an integrated circuit) or a liquid crystal display element. The device manufacturing method of the present invention is suitable for manufacturing micro devices.

20 ... main controller, 39 ₁ , 39 ₂ ... scale, 50 ... stage device, 62A, 62C, 62E, 62F ... head section, 64, 65, 67, 68 ... biaxial head, 64X, 65X, 67X, 68X ... X head, 64Y, 65Y, 67Y, 68Y ... Y head, 70Ax, 70Cx, 70Ex, 70Fx ... X encoder, 70Ay, 70Cy, 70Ey, 70Fy ... Y encoder, 72a-72d, 74, 76 ... Z head, 100 ... Exposure 118: Interferometer system, 124 ... Stage drive system, 150 ... Encoder system, 180 ... Surface position measurement system, 200 ... Measurement system, PL ... Projection optical system, PU ... Projection unit, W ... Wafer, WST ... Wafer stage , WTB ... Wafer table.

Claims (10)

An exposure apparatus that scans an object in a first direction with respect to illumination light to form a predetermined pattern on the object,
A moving body that holds the object and moves along a predetermined plane including the first direction and a second direction perpendicular thereto;
A pair of measurement surfaces extending in the first direction, the two-dimensional gratings being arranged on the upper surface of the movable body apart from each other in the second direction and having a periodic direction in the first and second directions on the upper surface;
At least one corresponding to each of the pair of measurement surfaces is provided, the measurement beam is irradiated to the first irradiation point on the corresponding measurement surface, and the return light of the measurement beam via the two-dimensional grating is received. Position measurement that has a plurality of heads including a plurality of first heads having at least the second direction as a measurement direction, and obtains position information of at least the moving body in the predetermined plane based on outputs of the plurality of heads A system and;
The first irradiation point is an exposure apparatus located on a straight line in the second direction passing through the irradiation center of the illumination light on the measurement surface.   The plurality of heads irradiate a measurement beam to a second irradiation point spaced a predetermined distance from the first irradiation point on the measurement surface to one side in the first direction, and return light of the measurement beam from the measurement surface. The exposure apparatus according to claim 1, further comprising: a plurality of second heads that receive light, wherein each of the plurality of second heads has at least the first direction as a measurement direction.   The plurality of heads irradiate a measurement beam to a third irradiation point spaced a predetermined distance from the first irradiation point on the measurement surface to the other side in the first direction, and return light of the measurement beam from the measurement surface. The exposure apparatus according to claim 2, further comprising: a plurality of third heads that receive light, wherein each of the plurality of third heads has at least a direction orthogonal to a predetermined plane as a measurement direction.   The exposure apparatus according to claim 2, wherein each of the plurality of first heads has a measurement direction in a direction orthogonal to the second direction and the predetermined plane.   2. The exposure apparatus according to claim 1, wherein each of the plurality of first heads has a measurement direction that is perpendicular to the first direction, the second direction, and the predetermined plane. A mark detection system for detecting a mark on the object;
Each of the plurality of heads is provided corresponding to each of the pair of measurement surfaces, and irradiates a measurement beam to a fourth irradiation point on the corresponding measurement surface, and the measurement beam is emitted from the measurement surface. It further includes a plurality of fourth heads that measure at least the second direction for receiving the return light, and the fourth irradiation point is an irradiation center of a detection beam irradiated on the object from the mark detection system. The exposure apparatus according to claim 1, wherein the exposure apparatus is located on a straight line in the second direction passing through a detection center of a mark detection system.   The plurality of heads are arranged at a fifth irradiation point that is spaced apart from the fourth irradiation point on the measurement surface irradiated with the measurement beam from each of the plurality of fourth heads by a predetermined distance to one side in the first direction. A plurality of fifth heads that irradiate a measurement beam and receive return light from the measurement surface of the measurement beam, and each of the plurality of fifth heads has at least the first direction as a measurement direction. 6. The exposure apparatus according to 6.   The plurality of first heads are arranged in the second direction with a separation distance shorter than a width in the second direction of the measurement surface opposed to the first head. The exposure apparatus described in 1. An optical system for irradiating the object with the illumination light;
A liquid supply system that supplies between the optical system and the moving body that holds the object;
The exposure apparatus according to any one of claims 1 to 8, further comprising: Forming a pattern on the object using the exposure apparatus according to claim 1;
Developing the object having the pattern formed thereon.

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