JP5565613B2 - Measuring method, exposure method, exposure apparatus, and device manufacturing method - Google Patents

Description

  The present invention relates to a measurement method, an exposure method and an exposure apparatus, and a device manufacturing method, and more specifically, a measurement method for measuring position information of a periodic pattern, an exposure method using the method, and an exposure for performing the exposure method. The present invention relates to an apparatus and a device manufacturing method using the exposure method.

  In a lithography process for manufacturing an electronic device (microdevice) such as a semiconductor element (such as an integrated circuit) or a liquid crystal display element, a pattern of a photomask or a reticle (hereinafter collectively referred to as “reticle”) is passed through a projection optical system. For example, a step-and-repeat type projection exposure apparatus (so-called stepper) that transfers onto an object to be exposed (hereinafter referred to as "wafer") such as a wafer coated with a photosensitive agent such as a photoresist or a glass plate. Alternatively, a projection exposure apparatus such as a step-and-scan projection exposure apparatus (so-called scanner) is mainly used.

  Since semiconductor elements and the like are formed by overlaying more than a dozen device patterns, the projection exposure apparatus requires accurate alignment between the pattern formed on the reticle and the pattern already formed on the wafer. Is done. Therefore, baseline measurement for measuring the distance (baseline) between the projection position of the reticle pattern and the detection center of the mark detection system for detecting the mark on the wafer (the projection position of the reticle pattern as part of the measurement operation) Is included). As a method for this reticle alignment, a method of measuring an aerial image of a measurement mark on a reticle using an aerial image measuring instrument provided with at least a part (including a slit for measurement) on a wafer stage is a recent exposure apparatus. Then, it may be adopted (for example, refer to Patent Document 1).

  However, when measuring the aerial image of the measurement mark using the aerial image measuring instrument, it is necessary to measure while moving the wafer stage provided with the measurement slit of the aerial image measuring instrument. It is measured using a measuring instrument such as an encoder (or interferometer). Along with the miniaturization of device rules, recently, measurement errors of measuring instruments, especially periodic measurement errors (periodic errors) are factors that cause measurement errors of mark image formation positions that cannot be ignored in aerial image measurement. Turned out to be. The same problem can occur when measuring the position of the periodic mark while moving the moving body, not limited to the aerial image measurement.

US Patent Application Publication No. 2008/0088843

According to the first aspect of the present invention, there is provided a measurement method for measuring position information of a periodic pattern, wherein the position information related to the periodic direction of the periodic pattern arranged on one of the moving body and the outside of the moving body is While driving the moving body in the periodic direction of the periodic pattern, at least one of the output of a position measurement system that measures the position of the moving body in the periodic direction and the other of the moving body and the outside of the moving body. And a step of measuring based on an output of a detection system that detects the periodic pattern, and in the measuring step, during the measurement, the pitch of the periodic pattern is equal to the periodic error of the position measuring system. It satisfies a predetermined relationship with respect to the measurement period of the position measurement system which is not a factor in the measurement error in the position of the periodic pattern, the predetermined relationship, the pitch of the periodic pattern, the self of the measurement cycle The number m times the measurement method is a relationship which should not is provided.

  Here, one of the pitch of the periodic pattern and the measurement period of the position measurement system is previously based on the other so that the periodic error of the position measurement system satisfies a predetermined relationship that does not cause the measurement error of the position of the periodic pattern. Alternatively, the driving speed of at least one of the moving body and the outside of the moving body may be adjusted during measurement.

  According to the measurement method of the present invention, even if the position of a moving body is measured using a position measurement system (for example, an encoder) that generates a periodic measurement error (period error), the position measurement of the periodic pattern can be performed with high accuracy. Can be done.

  According to a second 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, wherein the positional information of the periodic pattern is measured by the measurement method of the present invention. An exposure method including: driving a moving body that holds the object based on a measurement result of position information of the periodic pattern, and exposing the object with the energy beam is provided.

  According to this, since the position measurement of the highly accurate periodic pattern can be performed with high accuracy by the measurement method of the present invention, the moving body that holds the object is driven based on the measurement result of the position information, and the energy beam is used. By exposing the object, highly accurate exposure can be performed.

According to a third aspect of the present invention, exposing an object by the exposure method of the present invention;
Exposing the exposed object. A device manufacturing method is provided.

According to a fourth aspect of the present invention, there is provided an exposure apparatus for exposing an object with an energy beam to form a device pattern on the object, the moving body holding and moving the object; A position measurement system for measuring a position; a detection system for detecting a pattern or a pattern image, at least a part of which is provided on one of the movable body and the exterior of the movable body; and the movable body and the exterior of the movable body The detection for detecting the measurement information of the position of the moving body measured by the position measurement system and the periodic pattern or an image thereof while driving the moving body in the periodic direction of the periodic pattern arranged on the other side based on the output of the system, and a control device which measures positional information about the periodic direction of the periodic pattern; equipped with, in the measurement, the pitch of the periodic pattern is periodic error of the position measurement system is the periodic Pas Satisfies a predetermined relationship with respect to the measurement period of the position measurement system which is not a factor in the measurement error in the position of over emissions, the predetermined relationship, the pitch of the periodic pattern, in relation to not be a natural number m times the measurement cycle An exposure apparatus is provided.

  Here, one of the pitch of the periodic pattern and the measurement period of the position measurement system is previously based on the other so that the periodic error of the position measurement system satisfies a predetermined relationship that does not cause the measurement error of the position of the periodic pattern. Alternatively, the driving speed of at least one of the moving body and the outside of the moving body may be adjusted during measurement.

  According to the exposure apparatus of the present invention, even if the position of a moving object is measured using a position measurement system (for example, an encoder) that generates a periodic measurement error (period error), the position measurement of the periodic pattern can be performed with high accuracy. Can be 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 top view which shows arrangement | positioning of the stage apparatus and interferometer with which the exposure apparatus of FIG. 1 is provided. FIG. 2 is a plan view showing a measurement apparatus other than the interferometer system provided in the exposure apparatus of FIG. 1 together with a wafer stage. It is a top view which shows arrangement | positioning of an encoder head (X head, Y head) and an alignment system. 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 which shows an example of a structure of an encoder. FIG. 8A and FIG. 8B are diagrams for explaining an analysis method of an encoder measurement result. FIG. 9A is a diagram showing the aerial image measurement slit plate provided on the wafer table, FIG. 9B is a diagram showing the measurement mark provided on the reticle stage, FIG. 9C and FIG. (D) is a figure for demonstrating the scanning of the slit for aerial image measurement with respect to the projection image (aerial image) of a measurement mark. FIG. 10A shows a detection result (part 1) of the aerial image of the measurement mark, FIG. 10B shows a plot of the detection result (part 1) in units of 0.25 μm, and FIG. It is the figure which plotted the detection result (the 2) of the aerial image of a measurement mark by a 0.25 micrometer unit.

  Hereinafter, an embodiment of the present 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, the direction parallel to the optical axis AX of the projection optical system PL is the Z-axis direction, and the scanning direction in which the reticle R and the wafer W are relatively scanned in a plane perpendicular to the Z-axis direction is the Y-axis direction. The direction orthogonal to the axis is defined as the X-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are described as the θx, θy, and θz directions, respectively.

  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, a control system for these, and the like. In FIG. 1, wafer W is mounted on wafer stage WST.

  The illumination system 10 illuminates a slit-like illumination area IAR on the reticle R defined by a reticle blind (also called a masking system) with illumination light (exposure light) IL with a substantially uniform illuminance. The configuration of the illumination system 10 is disclosed in, for example, US Patent Application Publication No. 2003/0025890. Here, as an example of the illumination light IL, ArF excimer laser light (wavelength 193 nm) is used.

  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. 6) including, for example, a linear motor and the like, 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 (including rotation information in the θz direction) of reticle stage RST in the XY plane is formed on movable mirror 15 (or on the end face of reticle stage RST) by reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 116. 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. 6).

  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 projection optical system PL, for example, a refractive optical system including a plurality of optical elements (lens elements) arranged along 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 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. The 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) is passed through the projection optical system PL (projection unit PU) by the IL on the second surface (image surface) side. Is formed in 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 thereof. 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 this embodiment, a pattern is generated on the wafer W by the illumination system 10, the reticle R, and the projection optical system PL, and the pattern is formed on the wafer W by exposure of the sensitive layer (resist layer) on the wafer W by the illumination light IL. Is formed.

  As shown in FIG. 1, stage device 50 drives wafer stage WST disposed on base board 12, measurement system 200 (see FIG. 6) for measuring positional information of wafer stage WST, and wafer stage WST. A stage drive system 124 (see FIG. 6) is provided. As shown in FIG. 6, the measurement system 200 includes an interferometer system 118, an encoder system 150, and the like.

  Wafer stage WST is supported above base board 12 by a non-contact bearing (not shown) such as an air bearing with a clearance of about several μm. Wafer stage WST can be driven with a predetermined stroke in the X-axis direction and Y-axis direction by stage drive system 124 (see FIG. 6) including a linear motor and 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 measurement plate 30 is provided on the + Y side of the wafer holder (wafer W) on the upper surface of wafer table WTB. The measurement plate 30 is provided with a reference mark FM at the center, and a pair of aerial image measurement slit plates SL on both sides of the reference mark FM in the X-axis direction. As shown in FIG. 9A, each aerial image measurement slit plate SL has a linear opening pattern (X slit) SLX having a predetermined width (for example, 0.2 μm) whose longitudinal direction is the Y-axis direction. And a line-shaped opening pattern (Y slit) SLY having a predetermined width (for example, 0.2 μm) with the X-axis direction as a longitudinal direction is formed.

  Corresponding to each aerial image measurement slit plate SL, inside the wafer table WTB is an optical system including a lens and a light receiving element such as a photomultiplier tube (photomultiplier tube (PMT)). A pair of aerial image measuring devices 45A and 45B (see FIG. 6) which are arranged and similar to those disclosed in US Patent Application Publication No. 2002/0041377 and the like are provided. 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).

In addition, a scale used in an encoder system 150 described later is formed on the upper surface of wafer table WTB. More specifically, Y scales 39Y ₁ and 39Y ₂ are formed in regions on one side and the other side of the upper surface of wafer table WTB in the X-axis direction (left and right direction in FIG. 2). The Y scales 39Y ₁ and 39Y ₂ are, for example, reflective type gratings (for example, diffraction gratings) in which the Y axis direction is a periodic direction in which grid lines 38 having the X axis direction as the longitudinal direction are arranged at a predetermined pitch in the Y axis direction. ).

Similarly, X scale 39X ₁ , X scale 39X ₁ , and Y scale 39Y ₁ and 39Y ₂ are sandwiched between one side and the other side in the Y-axis direction (up and down direction in the drawing in FIG. 2) of wafer table WTB. 39X ₂ are formed respectively. The X scales 39X ₁ and 39X ₂ are, for example, reflection type gratings (for example, diffraction gratings) in which the X-axis direction is a periodic direction in which grid lines 37 having a longitudinal direction in the Y-axis direction are arranged in the X-axis direction at a predetermined pitch. ).

  The pitch of the grid lines 37 and 38 is set to 1 μm, for example. In FIG. 2 and other figures, the pitch of the grating is shown larger than the actual pitch for convenience of illustration.

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

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

  Further, on the surface on the + Y side of wafer table WTB, as shown in FIG. 2, a fiducial extending in the X-axis direction is the same as the CD bar disclosed in US Patent Application Publication No. 2008/0088843. A bar (hereinafter abbreviated as “FD bar”) 46 is attached. 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 LL. . 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 an alignment system described later is used.

In the exposure apparatus 100 of the present embodiment, as shown in FIGS. 4 and 5, the optical axis on a straight line (hereinafter referred to as a reference axis) LV parallel to the Y axis passing through the optical axis AX of the projection optical system PL. A primary alignment system AL1 having a detection center is arranged at a position a predetermined distance from AX on the -Y side. 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, and the drive mechanisms 60 _{1 to} 60 ₄ (see FIG. 6) are used in the X-axis direction. The relative positions of these detection areas can be adjusted.

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).

As shown in FIG. 3, interferometer system 118 irradiates reflecting surface 17a or 17b with an interferometer beam (length measuring beam), receives the reflected light, and positions wafer stage WST in the XY plane. Y interferometer 16, three X interferometers 126 to 128, and a pair of Z interferometers 43A and 43B. More specifically, 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 and B4 ₂ symmetric with respect to the reference axis LV, and a movable mirror 41 described later. Irradiate. Further, as shown in FIG. 3, the X interferometer 126 includes a pair of length measuring beams symmetrical with respect to a straight line (hereinafter referred to as a reference axis) LH parallel to the X axis orthogonal to the optical axis AX and the reference axis LV. B5 _1, B5 parallel measurement beam into at least three X-axis including ₂ irradiates the reflecting surface 17b. Further, the X interferometer 127 includes at least a length measuring beam B6 having a length measuring axis as a straight line LA (hereinafter referred to as a reference axis) LA parallel to the X axis orthogonal to the reference axis LV at the detection center of the alignment system AL1. The length measurement beam parallel to the two X axes is irradiated onto the reflecting surface 17b. In addition, the X interferometer 128 irradiates the reflection surface 17b with a measurement beam B7 parallel to the X axis.

  Position information from each interferometer of the interferometer system 118 is supplied to the main controller 20. Based on the measurement results of Y interferometer 16 and X interferometer 126 or 127, main controller 20 rotates in the θx direction (ie, pitching), θy in addition to the X and Y positions of wafer table WTB (wafer stage WST). Directional rotation (ie rolling) and θz direction rotation (ie yawing) 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 designed to have a length in the X-axis direction that is longer than the reflecting surface 17a of the wafer table WTB.

  A pair of Z interferometers 43A and 43B constituting a part of the interferometer system 118 (see FIG. 6) are provided facing the movable mirror 41 (see FIGS. 1 and 3). The Z interferometers 43A and 43B respectively irradiate the movable mirror 41 with two measurement beams B1 and B2 parallel to the Y axis, and each of the measurement beams B1 and B2 through the movable mirror 41, for example, a projection unit The fixed mirrors 47A and 47B fixed to a frame (not shown) that supports the PU are irradiated. 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 rotation information in the θz direction) in the XY plane of wafer stage WST (wafer table WTB) is mainly measured using encoder system 150 and surface position measurement system 180 described later. . Interferometer system 118 is used when wafer stage WST is located outside the measurement area of encoder system 150 and surface position measurement system 180 (for example, near the unloading position and loading position). Further, it is used as an auxiliary when correcting (calibrating) long-term fluctuations in the measurement results of the encoder system 150 and the surface position measurement system 180 (for example, due to deformation of the scale over time). Of course, the interferometer system 118, the encoder system 150, and the surface position measurement system 180 may be used in combination to measure all position information of the wafer stage WST (wafer table WTB).

  In the exposure apparatus 100 of the present embodiment, a plurality of encoder systems 150 are configured to measure the position (X, Y, θz) in the XY plane of the wafer stage WST independently of the interferometer system 118. A head unit is provided.

As shown in FIG. 4, four head units 62A, 62B, 62C, and 62D are arranged on the + X side, + Y side, -X side of the projection unit PU, and -Y side of the primary alignment system AL1, respectively. ing. Head units 62E and 62F are provided on both outer sides in the X-axis direction of the alignment systems AL1, AL2 _{1 to} AL2 ₄ , respectively. The head units 62A to 62F are fixed in a suspended state to a main frame (not shown) that holds the projection unit PU via support members. 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.

As shown in FIG. 5, the head units 62 </ b> A and 62 </ b> C include a plurality (here, five) of Y heads 65 _{1 to} 65 ₅ and Y heads 64 ₁ to 64 arranged on the reference axis LH with a spacing WD. ₅ is provided. Hereinafter, Y heads 65 _{1 to} 65 ₅ and Y heads 64 ₁ to 64 ₅ are also referred to as Y head 65 and Y head 64, respectively, as necessary.

The head units 62A and 62C use the Y scales 39Y ₁ and 39Y ₂ to measure the position (Y position) of the wafer stage WST (wafer table WTB) in the Y-axis direction (multi-lens Y linear encoders 70A and 70C). 6). In the following, the Y linear encoder is abbreviated as “Y encoder” or “encoder” as appropriate.

As shown in FIG. 5, the head unit 62B is arranged on the + Y side of the projection unit PU, and includes a plurality of (here, four) X heads 66 _{5 to} 66 ₈ arranged on the reference axis LV at intervals WD. I have. Further, head unit 62D is arranged on the -Y side of primary alignment system AL1, a plurality which are arranged at a distance WD on reference axis LV (four in this case) and a X heads 66 ₁ to 66 _4. Hereinafter, the X heads 66 _{5 to} 66 ₈ and the X heads 66 _{1 to} 66 ₄ are also referred to as the X head 66 as necessary.

The head units 62B and 62D use X scales 39X ₁ and 39X ₂ to measure the position (X position) of the wafer stage WST (wafer table WTB) in the X-axis direction (X position). 6). In the following, the X linear encoder is abbreviated as “X encoder” or “encoder” as appropriate.

Here, the interval WD in the X-axis direction of the five Y heads 65 and 64 (more precisely, the irradiation points on the scale of the measurement beam emitted by the Y heads 65 and 64) provided in the head units 62A and 62C, respectively. At the time of exposure or the like, it is determined that at least one head always faces the corresponding Y scales 39Y ₁ and 39Y ₂ (irradiates the measurement beam). Similarly, the interval WD in the Y-axis direction between adjacent X heads 66 (more precisely, the irradiation points on the scale of the measurement beam emitted by the X head 66) provided in the head units 62B and 62D is determined during exposure. , It is determined that at least one head always faces the corresponding X scale 39X ₁ or 39X ₂ (irradiates the measurement beam).

The distance between the most + Y side X heads 66 ₄ of the most -Y side of the X heads 66 ₅ and the head unit 62D of the head unit 62B is the movement of the Y-axis direction of wafer stage WST, between the two X heads The width of the wafer table WTB is set to be narrower than the width in the Y-axis direction so that it can be switched (connected).

Head unit 62E, as shown in FIG. 5, a Y heads _67i to 674 ₄ of the plurality of (four in this case).

Head unit 62F is equipped with a Y heads 68 ₁ to 68 ₄ of a plurality (four in this case). Y heads 68 ₁ to 68 _4, with respect to the reference axis LV, is disposed on the Y head 67 _{4-67 1} and symmetrical position. In the following, optionally, the Y head 67 _{4-67 1} and Y heads 68 ₁ to 68 _4, denoted respectively both Y heads 67 and Y heads 68.

At the time of alignment measurement, at least one Y head 67 and 68 faces the Y scales 39Y ₂ and 39Y ₁ , respectively. The Y position (and θz rotation) of wafer stage WST is measured by Y heads 67 and 68 (that is, Y encoders 70E and 70F (see FIG. 6) constituted by Y heads 67 and 68).

In this embodiment, the Y heads 67 ₃ and 68 ₂ that are adjacent to the secondary alignment systems AL2 ₁ and AL2 ₄ in the X-axis direction at the time of measuring the baseline of the secondary alignment system, etc. The Y positions of the FD bar 46 are measured at the positions of the respective reference gratings 52 by the Y heads 67 ₃ and 68 ₂ facing the gratings 52 and facing the pair of reference gratings 52, respectively. Hereinafter, encoders configured by Y heads 67 ₃ and 68 ₂ respectively facing the pair of reference gratings 52 are referred to as Y linear encoders 70E ₂ and 70F ₂ . For identification purposes, Y encoders composed of Y heads 67 and 68 facing Y scales 39Y ₂ and 39Y ₁ are referred to as Y encoders 70E ₁ and 70F ₁ .

As encoder system 150 of the heads of encoder 70A~70F constituting the (see FIG. 6) (64 ₁ to 64 _5, 65 ₁ to 65 _5, 66 ₁ to 66 _8, 67 ₁ to 67 _4, 68 ₁ to 68 _4), For example, an interference type encoder head disclosed in US Pat. No. 7,238,931 and US Patent Application Publication No. 2008/0088843 is used. The diffraction interference type encoder head will be described in detail later.

The measured values of the encoders 70A to 70F described above are supplied to the main controller 20. Main controller 20 determines position (X) of wafer stage WST in the XY plane based on the measurement values of three of encoders 70A to 70D or three of encoders 70E ₁ , 70F ₁ , 70B and 70D. , Y, θz).

Main controller 20 controls the rotation of FD bar 46 (wafer stage WST) in the θz direction based on the measurement values of linear encoders 70E ₂ and 70F ₂ .

  In addition, in the exposure apparatus 100 of this embodiment, a multipoint focal position detection system including an irradiation system 90a and a light receiving system 90b for detecting the Z position on the surface of the wafer W at a large number of detection points in the vicinity of the projection unit PU. (Hereinafter abbreviated as “multi-point AF system”). As the multipoint AF system, an oblique incidence type multipoint AF system having the same configuration as that disclosed in, for example, US Pat. No. 5,448,332 is adopted. The multi-point AF irradiation system 90a and the light receiving system 90b are arranged in the vicinity of the head units 62A and 62B as disclosed in, for example, US Patent Application Publication No. 2008/0088843, and the wafer alignment is performed. The position information (surface position information) in the Z-axis direction may be measured (focus mapping is performed) on almost the entire surface of the wafer W only by scanning the wafer W once in the Y-axis direction. In this case, it is desirable to provide a surface position measurement system that measures the Z position of wafer table WTB during its focus mapping.

  FIG. 6 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 the exposure apparatus 100 of the present embodiment configured as described above, the unloading position UP (in accordance with a procedure similar to the procedure disclosed in the embodiment of US Patent Application Publication No. 2008/0088843, for example. The unloading of the wafer W at the loading position LP (see FIG. 4), the loading of the new wafer W onto the wafer table WTB at the loading position LP (see FIG. 4), the reference mark FM of the measurement plate 30 and the primary alignment system AL1 are used. Processing of the first half of the baseline check of the primary alignment system AL1, resetting (resetting) the origin of the encoder system and interferometer system, alignment measurement of the wafer W using the alignment systems AL1, AL2 _{1 to} AL2 ₄ and an aerial image measurement device Primary alignment system using 45A and 45B On the wafer W in the step-and-scan method based on the position information of each shot area on the wafer obtained as a result of the L1 baseline check and alignment measurement and the latest alignment system baseline A series of processing using wafer stage WST, such as exposure of a plurality of shot areas, is executed by main controller 20. Detailed description is omitted.

The baseline measurement of the secondary alignment systems AL2 _{1 to} AL2 ₄ is performed at an appropriate timing by the encoders 70E ₂ and 70F ₂ described above in the same manner as the method disclosed in US Patent Application Publication No. 2008/0088843. Based on the measured value, the reference mark M on the FD bar 46 in each field of view is adjusted using the alignment systems AL1, AL2 _{1 to} AL2 ₄ with the θz rotation of the FD bar 46 (wafer stage WST) adjusted. It is done by measuring simultaneously.

  In the present embodiment, main controller 20 uses encoder system 150 (see FIG. 6), and in the effective stroke area of wafer stage WST, that is, in the area where wafer stage WST moves for alignment and exposure operations, A position in the direction of three degrees of freedom (X, Y, θz) can be measured.

FIG. 7 shows a configuration of an encoder 70C as a representative of the encoders 70A to 70F. The encoder 70C (head unit 62C) will be described below, and the configuration and measurement principle of the encoder will be described. In FIG. 7, the measurement beam is irradiated to the Y scale 39Y ₂ from one Y head 64 of the head unit 62C constituting the encoder 70C.

The Y head 64 is roughly divided into three parts: an irradiation system 64a, an optical system 64b, and a light receiving system 64c. Irradiation system 64a includes a light source for emitting a laser beam LB _0, for example, a semiconductor laser LD, a lens L1 placed on the optical path of the laser beam LB _0, the. The optical system 64b includes a polarization beam splitter PBS, a pair of reflection mirrors R1a and R1b, lenses L2a and L2b, quarter-wave plates (hereinafter referred to as λ / 4 plates) WP1a and WP1b, and reflection mirrors R2a and R2b. Etc. The light receiving system 64c includes a polarizer (analyzer), a photodetector, and the like.

The laser beam LB ₀ emitted from the semiconductor laser LD is incident on polarization beam splitter PBS via lens L1, is polarized separated into two measurement beams LB _1, LB _2. Here, “polarization separation” means that the incident beam is separated into a P-polarized component and an S-polarized component. The measurement beam LB ₁ transmitted through the polarization beam splitter PBS reaches the reflection type diffraction grating RG formed on the Y scale 39Y ₁ via the reflection mirror R1a, and the measurement beam LB ₂ reflected by the polarization beam splitter PBS is reflected by the reflection mirror. It reaches the reflection type diffraction grating RG via R1b.

A diffraction beam of a predetermined order generated from the diffraction grating RG by irradiation of the measurement beams LB ₁ and LB ₂ , for example, a first-order diffracted beam is converted into circularly polarized light by the λ / 4 plates WP1b and WP1a via the lenses L2b and L2a, respectively. After that, the light is reflected by the reflection mirrors R2b and R2a, passes through the λ / 4 plates WP1b and WP1a again, follows the same optical path as the forward path in the opposite direction, and travels toward the polarization beam splitter PBS.

The polarization directions of the two diffracted beams toward the polarization beam splitter PBS are rotated 90 degrees from the original polarization direction. Therefore, the diffracted beam derived from the measurement beam LB ₁ that has passed through the polarization beam splitter PBS first is reflected by the polarization beam splitter PBS. On the other hand, the diffracted beam derived from the measurement beam LB ₂ previously reflected by the polarization beam splitter PBS is transmitted through the polarization beam splitter PBS and condensed coaxially with the first-order diffraction beam of the measurement beam LB ₁ . Then, these two diffracted beams, then is sent to the light receiving system 64c as the output beam LB _3.

Two diffracted beams in the output beam LB ₃ transmitted to the light receiving system 64c (more precisely, S and P polarization components of the output beam LB ₃ derived from the measurement beams LB ₁ and LB ₂ ) are received by the light receiving system 64c. The polarization direction is aligned by an internal analyzer (not shown) and becomes interference light. Further, as disclosed in, for example, US Patent Application Publication No. 2003/0202189, the interference light is branched into four. The four branched light beams are received by a photodetector (not shown) after their phases are relatively shifted by 0, π / 2, π, and 3π / 2, and each light intensity (I ₁ , I ₂ , I ₃ , and I ₄ ) and sent to the main controller 20 as an output of the Y encoder 70C.

Main controller 20 obtains relative displacement ΔY between Y head 64 and scale 39Y ₁ from the output of Y encoder 70C. Here, the calculation method of the relative displacement ΔY in this embodiment will be described in detail including its principle. For simplicity, let us consider a situation in which the intensities of the measurement beams LB ₁ and LB ₂ are equal to each other. In this situation, the outputs I _{1 to} I ₄ are expressed as follows:

I ₁ = A (1 + cos (φ)) ∝I (1a)
I ₂ = A (1 + cos (φ + π / 2)) (1b)
I ₃ = A (1 + cos (φ + π)) (1c)
I ₄ = A (1 + cos (φ + 3π / 2)) (1d)
Here, φ is a phase difference between the measurement beams LB ₁ and LB ₂ (the S and P polarization components of the output beam LB ₃ derived therefrom).

Main controller 20 obtains differences I ₁₃ and I ₄₂ represented by the following expressions (2a) and (2b) from outputs I _{1 to} I ₄ .

I ₁₃ = I ₁ −I ₃ = 2A cos (φ) (2a)
I ₄₂ = I ₄ −I ₂ = 2Asin (φ) (2b)
The differences I ₁₃ and I ₄₂ may be obtained optically (or electrically) using an optical circuit (or electrical circuit) introduced into the photodetector.

Here, in order to explain the principle of correction of the outputs I _{1 to} I ₄ of the Y encoder 70C (head 64), as shown in FIG. 8A, a point ρ (I ₁₃ plotted on the orthogonal coordinate system is used. , I ₄₂ ). 8A and 8B, the point ρ (I ₁₃ , I ₄₂ ) is represented using a vector ρ, and the phase of the point ρ (I ₁₃ , I ₄₂ ) is represented as φ. Yes. The length of the vector ρ, that is, the distance from the origin O of the point ρ (I ₁₃ , I ₄₂ ) is 2A.

In the ideal state, the intensity I of the interference light LB ₃ is always constant. Accordingly, the amplitudes A of the outputs I ₁ , I ₂ , I ₃ , and I ₄ are always constant. Therefore, in FIG. 8A, a point ρ (I ₁₃ , I ₄₂ ) has a distance (radius) from the origin along with a change in the intensity I of the interference light LB ₃ (that is, a change in the outputs I _{1 to} I ₄ ). Move on 2A circumference.

In the ideal state, the intensity I of the interference light LB ₃ changes sinusoidally when the Y scale 39Y ₁ (ie, the wafer stage WST) is displaced in the measurement direction (the periodic direction of the diffraction grating, ie, the Y-axis direction). To do. Similarly, the intensities I ₁ , I ₂ , I ₃ , and I ₄ of the _four branched lights change sinusoidally as represented by the equations (1a), (1b), (1c), and (1d), respectively. To do. In this ideal state, the phase difference φ is equivalent to the phase φ at the point ρ (I ₁₃ , I ₄₂ ) in FIG. The phase difference φ (hereinafter referred to as a phase unless otherwise distinguished) changes as follows with respect to the relative displacement ΔY.

φ (ΔY) = 2πΔY / (p / 4n) + φ ₀ (3)
Here, p is the pitch of the diffraction grating of the scale 39Y ₁ , n is the diffraction order (eg, n = 1), and φ ₀ is a constant phase determined by boundary conditions (eg, definition of the reference position of the displacement ΔY).

From Equation (3), it can be seen that the phase φ does not depend on the wavelengths of the measurement beams LB ₁ and LB ₂ . It can also be seen that the phase φ increases (decreases) by 2π every time the displacement ΔY increases (decreases) by the measurement unit p / 4n. Therefore, it can be seen that the intensity I and the outputs I ₁ , I ₂ , I ₃ , and I ₄ of the interference light LB ₃ oscillate every time the displacement ΔY increases or decreases by the measurement unit.

The relationship between the phase φ represented by the equation (3) and the displacement ΔY and the relationship between the outputs I _{1 to} I ₄ represented by the equations (1a) to (1d) and the phase φ (that is, the differences I ₁₃ and I ₄₂ and the displacement (Relationship with ΔY), the point ρ (I ₁₃ , I ₄₂ ) moves on the circumference of the radius 2A from the point a to the point b as shown in FIG. 8B, for example, as the displacement ΔY increases. Rotate counterclockwise. Conversely, the point ρ (I ₁₃ , I ₄₂ ) rotates clockwise on the circumference according to the decrease in the displacement ΔY. The point ρ (I ₁₃ , I ₄₂ ) goes around the circumference every time the displacement ΔY increases (decreases) in the measurement unit.

Therefore, main controller 20 counts the number of rounds of point ρ (I ₁₃ , I ₄₂ ) with reference to a predetermined reference phase (for example, constant phase φ ₀ ). This number of rotations is equal to the number of vibrations of the intensity I of the interference light LB ₃ . The counted value (count value) is expressed as c _ΔY . Further, main controller 20 obtains a phase displacement φ ′ = φ−φ ₀ with respect to the reference phase of point ρ (I ₁₃ , I ₄₂ ). From the count value c _ΔY and the phase displacement φ ′, a measured value C _ΔY of the displacement ΔY is obtained as follows.

_CΔY = (p / 4n) × ( _cΔY + φ ′ / 2π) (4)
Here, the constant phase φ ₀ is a phase offset (defined as 0 ≦ φ ₀ <2π), and the phase φ (ΔY = 0) at the reference position of the displacement ΔY is held.

  As is apparent from the above description, the Y encoder 70C has a measurement period equal to the measurement unit λ = p / 4n.

Note that the proportional relationship between the phase φ and the displacement ΔY may be lost due to interference with stray light, for example. In that case, even with the ideal outputs I _{1 to} I ₄ as described above, an error having a period equal to the measurement period may occur with respect to the measured value C _ΔY of the displacement ΔY. Further, if the outputs I _{1 to} I ₄ deviate from the ideal output, an error in calculating the phase φ occurs, and thus an error having a period equal to the measurement period may occur. Such errors having a period equal to the measurement period are collectively referred to as a period error.

  The heads 65, 66, 67, and 68 included in the other heads in the head unit 62C and the head units 62A, 62B, 62D, 62E, and 62F are configured similarly to the head 64 (encoder 70C).

Further, in the present embodiment, by adopting the arrangement of the encoder head as described above, at least one X head 66 is always provided on the X scale 39X ₁ or 39X ₂ and at least one Y head 65 is provided on the Y scale 39Y _1. (or 68) is, Y at least one of Y heads 64 to the scale 39Y ₂ (or 67) opposes respectively. From the encoder head facing the scale, the measurement results of the above-described branched light intensities I ₁ , I ₂ , I ₃ , and I ₄ are supplied to the main controller 20. Main controller 20 determines, based on the supplied measurement results I ₁ , I ₂ , I ₃ , and I ₄ , the displacement of wafer stage WST in the measurement direction of each head (more precisely, the scale on which the measurement beam is projected). Displacement). The obtained result is treated as a measurement value of the above-described encoder 70A, 70C and 70B or 70D (or encoder 70E ₁ , 70F ₁ and 70B or 70D).

  In the present embodiment, for example, in the process of the latter half of the baseline check of the primary alignment system AL1 (so-called reticle alignment), the aerial image measurement devices 45A and 45B are used to provide the reticle R (or reticle stage RST). A spatial image (projected image) of the pair of measurement marks PM on the reticle reference plate RFM) is measured.

  First, main controller 20 drives wafer stage WST (wafer table WTB) to move measurement plate 30 on wafer table WTB onto optical axis AX of projection optical system PL. At the same time, main controller 20 drives reticle stage RST to position reticle R (or reticle reference plate RFM) on optical axis AX.

  On reticle R (or reticle reference plate RFM), a pair of measurement marks PM is formed in an arrangement corresponding to the arrangement of a pair of aerial image measurement slit plates SL on wafer table WTB. As the measurement mark PM, as shown in FIG. 9B, a line-shaped opening pattern (hereinafter abbreviated as a line pattern) having a predetermined width (for example, 1 μm) whose longitudinal direction is the Y-axis direction is the X-axis direction. A two-dimensional mark including a plurality of X measurement marks PMX arranged and a Y measurement mark PMY having a plurality of line patterns having a predetermined width (for example, 1 μm) with the X axis direction as a longitudinal direction arranged in the Y axis direction is used. ing.

  Next, main controller 20 illuminates a region including at least a pair of measurement marks PM on reticle R (or reticle reference plate RFM) with illumination light IL, and the illumination light that has passed through reticle R (or reticle reference plate RFM). The IL is projected onto a pair of aerial image measurement slit plates SL on the measurement plate 30 via the projection optical system PL. Accordingly, for example, as shown in FIGS. 9C and 9D, the image PMX ′ of the X measurement mark PMX and the image PMY ′ of the Y measurement mark PMY in the measurement mark PM are respectively measured by the aerial image measurement. Projection is performed in the vicinity of the X slit SLX on the −X side and the vicinity of the Y slit SLY of the slit plate SL.

  Then, when measuring the aerial image of the X measurement mark PMX, the main controller 20 illuminates the pair of measurement marks PM with the illumination light IL as described above, with a white arrow in FIG. 9C. As shown, wafer stage WST is driven in the -X direction. Accordingly, the X slit SLX of the pair of aerial image measurement slit plates SL is scanned in the X-axis direction with respect to the projection image (spatial image) PMX ′ of the corresponding X measurement mark PMX. During scanning, when the X slit SLX overlaps the image of a part of the line pattern of the projected image (aerial image) PMX ′, the illumination light IL passes through the slit SLX and is detected by the aerial image measuring devices 45A and 45B. .

  Further, when measuring the aerial image of the Y measurement mark PMY, the main controller 20 illuminates the pair of measurement marks PM with the illumination light IL as described above, with a white arrow in FIG. 9D. As shown, wafer stage WST is driven in the + Y direction. Thereby, the Y slit SLY of the pair of aerial image measurement slit plates SL is scanned in the Y-axis direction with respect to the projection image (spatial image) PMY ′ of the corresponding Y measurement mark PMY, and the illumination light IL transmitted through the slit SLY. Is detected by the aerial image measuring devices 45A and 45B.

  Main controller 20 captures the light quantity signals from aerial image measurement devices 45A and 45B together with position measurement information of wafer stage WST measured by encoder system 150. Thus, main controller 20 obtains a profile (aerial image profile) of projected image (aerial image) PMX ′ (or PMY ′) of X measurement mark PMX (or Y measurement mark PMY).

  FIG. 10A shows a measurement result of the aerial image (aerial image profile) of the X measurement mark PMX as an example. Here, the X measurement mark PMX is composed of eight line patterns arranged at a pitch P of 2 μm / β in the X-axis direction (see FIG. 9B). Here, β is the projection magnification of the projection optical system PL. Accordingly, an aerial image profile having eight peaks arranged at intervals of 2 μm is obtained.

  For convenience of explanation, the X measurement mark projected on the wafer stage WST (aerial image measurement slit plate SL) through the projection optical system PL with the arrangement pitch of the X measurement marks PMX (Y measurement mark PMY). It is expressed by using an arrangement pitch of images of PMX (Y measurement mark PMY). That is, the product of the actual arrangement pitch and the projection magnification β is the arrangement pitch P.

FIG. 10B shows an example of an aerial image profile in which the horizontal axis X is drawn with a period of 0.25 μm. Here, in the exposure apparatus 100 of the present embodiment, the X scales 39X ₁ and 39X ₂ (and the Y scales 39Y ₁ and 39Y ₂ ) are composed of diffraction gratings arranged at a 1 μm pitch (p). In addition, encoder heads 64, 65, 66, 67, 68 using primary (n = 1) diffracted light are employed. Accordingly, the measurement unit λ (= p / 4n) of the encoders 70A to 70D (encoder heads 64, 65, 66, 67, 68) is 0.25 μm. That is, the cycle of 0.25 μm is the same as the measurement unit of the encoders 70A to 70D.

  Since the arrangement pitch P (= 2 μm) of the X measurement marks PMX is a natural number multiple of the period (that is, the measurement unit is 0.25 μm), in the aerial image profile (aerial image profile in the conventional example) of FIG. Eight peaks (see FIG. 10A) derived from the eight line patterns of the X measurement mark PMX are overlapped within a measurement error and appear as one peak. Therefore, when the cyclic error of the encoders 70A to 70D as described above occurs, the cyclic error equally affects each of the eight peaks.

  In the aerial image measurement of the projection optical system PL, as disclosed in, for example, US Patent Application Publication No. 2002/0041377, a plurality of aerial image profiles derived from a periodic pattern in the X measurement mark PMX, for example. A slice method or other waveform processing algorithm is applied to the peak waveform to determine the edge position (X position) of each line pattern. Then, for example, the average of a pair of edge positions of each line pattern is used as the position of the line pattern, and the position of the X measurement mark is based on the average of the positions of two line patterns positioned symmetrically with respect to the mark center by design. Is done. The line width of each line pattern is obtained in the same manner. With respect to the aerial image profile of FIG. 10B, as described above, errors derived from the encoder cyclic error are equally generated in each of the eight peak waveforms. Measurement errors are included in the position of the required line pattern, the position of the X measurement mark, etc. without being reduced.

  Therefore, in this embodiment, in principle, a periodic pattern having an arrangement pitch P (≠ mλ) that is different from a natural number (m) times the measurement unit λ of the encoders 70A to 70D is employed as the X measurement mark PMX (Y measurement mark PMY). To do. Further, in the aerial image measurement of the measurement mark PM, in order to effectively suppress the occurrence of mark position errors (imaging position measurement errors) accompanying the cyclic errors of the encoders 70A to 70D, the periodic pattern array pitch P is It is determined to be (m + 1 / n) times the measurement unit λ, that is, (m + 1 / n) λ. Here, m is a natural number, and n is a natural number of 2 or more.

  FIG. 10C shows the measurement result of the aerial image (spatial image profile) of the X measurement mark PMX with respect to the arrangement pitch P = (m + 1 / n) λ = 2.03125 μm. However, it was determined that m = n = 8. The aerial image profile is drawn on the horizontal axis X with a period of 0.25 μm.

  In the aerial image profile of FIG. 10C, the array pitch P is shifted from the natural number multiple (mλ) of the measurement unit λ by λ / n (0.03125 μm), so that eight peaks appear at different positions. Therefore, the slice method or other waveform processing algorithm is applied to the eight peak waveforms to determine the edge position (X position) of each line pattern, and the average of a pair of edge positions of each line pattern is used as the position of the line pattern. When determining the position of the X measurement mark based on the average of the positions of two line patterns positioned symmetrically with respect to the mark center by design or by design, errors due to the periodic error of the encoder are almost canceled by the averaging effect Is done. As a result, in the measurement of the aerial image of the mark, the occurrence of the measurement error of the imaging position accompanying the periodic error of the encoders 70A to 70D can be effectively suppressed.

  In order to maximize the above-described averaging effect, it is desirable that the natural number n is a certain large number, for example, a number of 4 or more. Further, as the X measurement mark PMX (Y measurement mark PMY), a line pattern having a number that is a multiple of two or more natural numbers n arranged at the pitch P in the X-axis direction (Y-axis direction) is adopted.

  Up to now, the aerial image measurement of the measurement mark in the latter half of the baseline check of the primary alignment system AL1 (so-called reticle alignment) has been described. However, the measurement error of the image formation position of the mark described above has occurred. As a technique for preventing this, measurement of optical characteristics (for example, distortion, coma aberration) of the projection optical system PL using an optical characteristic measurement mark using a reticle reference plate RFM (or a reticle for measurement) (for example, the above-mentioned) (Details are disclosed in, for example, US Patent Application Publication No. 2002/0041377), and the like.

  As described above in detail, in exposure apparatus 100 of the present embodiment, main controller 20 performs wafer stage WST in, for example, the latter half of the baseline check of primary alignment system AL1 (so-called reticle alignment). Scanning is performed in the periodic direction of the measurement mark PM to be measured, and the intensity of the aerial image of the measurement mark PM on the reticle stage RST by the projection optical system PL is set on the wafer stage WST with some of the components (measurement slits SLX and SLY are provided. The position of the wafer stage WST is detected by using the aerial image measuring devices 45A and 45B on which the aerial image measuring slit plate SL) is disposed and measured by the output of the aerial image measuring devices 45A and 45B and the encoder system 150. The measurement position of the aerial image of the measurement mark PM is measured based on the measurement information of . During measurement, the pitches of the measurement marks PMX and PMY, which are periodic patterns included in the measurement mark PM, and the measurement periods of the encoders 70A and 70C (70B and 70D) of the encoder system 150 are the encoders 70A and 70C (70B and 70D). ) Satisfies a predetermined relationship that does not cause a measurement error of the positions of the measurement marks PMX and PMY (more precisely, the imaging positions of the aerial images of the measurement marks PMX and PMY). In the present embodiment, in order to satisfy this predetermined relationship, for example, periodic patterns having a pitch different from a natural number (m) times the measurement period of each encoder 70A, 70C (70B, 70D) of the encoder system 150 are used as measurement marks PMX, PMY. It is used. More specifically, a periodic pattern having an arrangement pitch P that is (m + 1 / n) times the measurement unit λ of the encoders 70A to 70D is employed as the X measurement mark PMX (Y measurement mark PMY). Here, m is a natural number, and n is a natural number of 2 or more. Therefore, according to the present embodiment, even if the position measurement of wafer stage WST is performed using encoder system 150 that generates a periodic measurement error (period error) as a position measurement system, X measurement mark PMX (Y measurement mark PMY) ) Position measurement (imaging position measurement) can be performed with high accuracy, and as a result, the latter half of the baseline check of the primary alignment system AL1 can be performed with high accuracy.

  Further, in the exposure apparatus 100 of the present embodiment, the base line of the primary alignment system AL1 can be obtained with high accuracy, and the wafer stage WST is driven by the step-and-scan method using the base line, so The pattern of the reticle R is transferred to each shot area. For this reason, the pattern of the reticle R can be accurately transferred to each shot area on the wafer.

  In the above embodiment, the line and space pattern is used as the measurement marks PMX and PMY. However, the present invention is not limited to this, and a pattern having any shape may be used as long as it is a periodic pattern.

  In the above embodiment, the wafer stage WST is disposed on the image plane side of the projection optical system, and a part of the components of the aerial image measurement devices 45A and 45B (aerial image measurement slit plate SL) is provided on the wafer stage WST. However, the present invention is not limited to this. For example, another stage that does not hold the wafer is provided in addition to the wafer stage WST that holds the wafer, and at least one of the aerial image measurement devices 45A and 45B is provided on this other stage. You may employ | adopt the structure which arrange | positions a part.

  In the above embodiment, the aerial image measurement device (detector) in which at least a part (aerial image measurement slit plate SL) is arranged on wafer stage WST in a state where reticle stage RST provided with measurement mark PM is stationary. ) The case where the aerial image of the measurement mark PM is detected while driving the wafer stage WST using 45A and 45B has been described. However, the present invention is not limited to this, and the relationship between the pitch of the periodic pattern in the measurement mark and the measurement period of the position measurement system of wafer stage WST is that the measurement system cyclic error is the measurement error of the periodic pattern position in the measurement mark. Any relationship that does not cause a factor (hereinafter referred to as a predetermined relationship for convenience) may be used. Therefore, for example, the measurement mark PM (that is, the reticle stage RST) and the aerial image measurement devices (detectors) 45A and 45B (that is, the wafer stage WST) are relatively driven in the measurement direction of the measurement mark, and the periodic pattern in the measurement mark. Can be effectively shifted from a natural number (m) times the measurement period. In that case, the driving speed v of reticle stage RST is given as 1 / (1 + mn) times (n is a natural number of 2 or more) the driving speed V of wafer stage WST. However, for simplicity, the projection magnification β of the projection optical system PL is set to 1. Further, the detection result of the aerial image is processed in consideration of the position information of the reticle stage RST. For example, the detection result of the aerial image is processed with respect to the relative position information of wafer stage WST with respect to reticle stage RST instead of the position information of wafer stage WST.

  If the relationship between the pitch of the periodic pattern in the measurement mark and the measurement cycle of the position measurement system of wafer stage WST is the predetermined relationship, for example, measurement mark PM is provided on wafer stage WST, and wafer stage WST is provided. It is also possible to employ a configuration in which aerial image measurement devices 45A and 45B fixed outside are provided and the movable measurement mark PM is detected using the fixed aerial image measurement devices 45A and 45B.

  In the present embodiment, the pitch P of the periodic pattern in the measurement mark is determined based on the measurement cycle λ of the position measurement system. Conversely, the measurement cycle λ of the position measurement system is adjusted based on the pitch P. Is also possible. For example, in the case of an encoder, the pitch p of the diffraction grating formed on the scale is changed, and in the case of an interferometer, the measurement beam wavelength is changed so as to give a pitch P = (m + 1 / n) λ. Adjust the period λ.

  In the present embodiment, the pattern detection method and the pattern detection system of the present invention are applied to the case where the encoder system 150 is employed as a position measurement system for measuring the position of the wafer stage WST in the aerial image measurement. In addition to the interferometer system 118, any measuring instrument having a measurement cycle can be applied as a position measurement system.

  In the present embodiment, the pattern detection method and the pattern detection system of the present invention have been described by taking the aerial image measurement for the purpose of measuring the optical characteristics of the projection optical system PL as an example. The present invention can be applied to any pattern detection that detects a periodic pattern using a detector while moving one of the detector and the periodic pattern.

  Note that the configuration of each measuring apparatus such as the encoder system described in the above embodiment is merely an example, and the present invention is of course not limited thereto. For example, in the above-described embodiment, an encoder system having a configuration in which a lattice unit (Y scale, X scale) is provided on a wafer table (wafer stage), and an X head and a Y head are arranged outside the wafer stage so as to face the lattice unit. Although the case where it is adopted is exemplified, the present invention is not limited to this. For example, as disclosed in US Patent Application Publication No. 2006/0227309, an encoder head is provided on the wafer stage, and the wafer stage is opposed to the encoder head. You may employ | adopt the encoder system of the structure which arrange | positions a grating | lattice part (For example, the two-dimensional grating | lattice or the two-dimensionally arranged one-dimensional grating | lattice part) outside. In this case, a head (Z head) of the surface position sensor may also be provided on the wafer stage, and the surface of the grating portion may be a reflective surface to which the measurement beam of the Z head is irradiated.

  In the above embodiment, as disclosed in, for example, US Patent Application Publication No. 2008/0088843, an encoder head and a Z head may be separately provided in the head units 62A and 62C. A single head having the functions of the encoder head and the Z head may be provided in place of the set of the encoder head and the Z head.

  In the above-described embodiment, the case where the present invention is applied to a dry type exposure apparatus that exposes the wafer W without using liquid (water) has been described. As disclosed in Publication No. 1420298, International Publication No. WO 2004/055803, U.S. Pat. No. 6,952,253, etc., an optical path of illumination light is included between the projection optical system and the wafer. The present invention can also be applied to an exposure apparatus that forms an immersion space and exposes the wafer with illumination light through the projection optical system and the liquid in the immersion space. The present invention can also be applied to an immersion exposure apparatus disclosed in, for example, US Patent Application Publication No. 2008/0088843.

  In the above embodiment, the case where the present invention is applied to a scanning exposure apparatus such as a step-and-scan method has been described. However, the present invention is not limited to this, and the present invention is applied to a stationary exposure apparatus such as a stepper. May be. The present invention can also be applied to a step-and-stitch reduction projection exposure apparatus, a proximity exposure apparatus, or a mirror projection aligner that synthesizes a shot area and a shot area. 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 present invention can also be applied to a multi-stage type exposure apparatus provided with a stage. Further, as disclosed in, for example, US Pat. No. 7,589,822, an exposure including a measurement stage including a measurement member (for example, a reference mark and / or a sensor) separately from the wafer stage. The present invention can also be applied to an apparatus.

  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, U.S. 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 as vacuum ultraviolet light, For example, a harmonic which 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, in recent years, in order to expose a pattern of 70 nm or less, EUV (Extreme Ultraviolet) light in a soft X-ray region (for example, a wavelength region of 5 to 15 nm) is generated using an SOR or a plasma laser as a light source, and its exposure wavelength Development of an EUV exposure apparatus using an all-reflection reduction optical system designed under (for example, 13.5 nm) and a reflective mask is underway. In this apparatus, since a configuration in which scanning exposure is performed by synchronously scanning the mask and the wafer using arc illumination is conceivable, the present invention can also be suitably applied to such an apparatus. In addition, the present invention can be applied to an exposure apparatus using a charged particle beam 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.

  Further, for example, the present invention 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 present invention 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 present invention 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 measurement method of the present invention is suitable for measuring position information of a periodic pattern. The exposure method and exposure apparatus of the present invention are suitable for transferring a pattern onto 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.

10 ... illumination system 20 ... main control unit, 39X _1, 39X ₂ ... X scales, 39Y _1, 39Y ₂ ... Y scales, 45A, 45B ... aerial image measuring unit, 50 ... stage device, 62a to 62f ... a head unit, 64, 65 ... Y head, 66 ... X head, 67, 68 ... Y head, 70A, 70C ... Y encoder, 70B, 70D ... X encoder, 100 ... Exposure apparatus, 124 ... Stage drive system, 150 ... Encoder system, PL Projection optical system, PM (PMX, PMY) ... Measurement mark (X measurement mark, Y measurement mark), PU ... Projection unit, RST ... Reticle stage, R ... Reticle, W ... Wafer, WST ... Wafer stage, WTB ... Wafer table.

Claims (25)

A measurement method for measuring position information of a periodic pattern,
Position information regarding the periodic direction of the periodic pattern arranged on one of the moving body and the outside of the moving body is used to determine the position of the moving body with respect to the periodic direction while driving the moving body in the periodic direction of the periodic pattern. A step of measuring based on an output of a position measurement system to be measured, and an output of a detection system in which at least a part thereof is provided on the other of the moving body and the outside of the moving body, and detecting the periodic pattern,
In the measuring step, during the measurement, the pitch of the periodic pattern satisfies a predetermined relationship with the measurement cycle of the position measurement system in which the periodic error of the position measurement system does not cause a measurement error of the position of the periodic pattern. ,
The measurement method in which the predetermined relationship is a relationship in which a pitch of the periodic pattern is not a natural number m times the measurement period . 2. The measurement method according to claim 1 , wherein the predetermined relationship is a relationship in which n is a natural number of 2 or more and a pitch of the periodic pattern is equal to (m + 1 / n) times the measurement cycle. In the measuring step, the periodic pattern arranged outside the movable body is illuminated with illumination light, and at least a part of the illumination light via the periodic pattern and the optical system is provided on the movable body. measurement method according to claim 1 or 2 is received by the detection system. In the step of the measurement, and the pitch measurement cycle of the position measurement system of the periodic pattern, so as to satisfy the predetermined relationship, together with the movable body, to claim 3 which drives the periodic pattern in the periodic direction The measurement method described. 5. The measurement method according to claim 4 , wherein in the measuring step, the periodic pattern is driven at a speed 1 / (1 + mn) times the driving speed of the moving body, where m is a natural number and n is a natural number of 2 or more. In the step of the measurement, further based on the output of another position measurement system for measuring the position of the periodic pattern about the periodic direction, according to claim 4 or 5 measures positional information about the periodic direction of the periodic pattern Measurement method. The measurement method according to claim 2 , wherein the n is a multiple of four. The periodic pattern, the measurement method according to any one of claims 2,5～7 containing the number of patterns is a multiple of the n arranged in the periodic direction. In the measurement step, the head is provided on one of the moving body and the outside of the moving body, irradiates measurement light on the measurement surface provided on the other, and receives light from the measurement surface, The measurement method according to claim 1 , wherein a position measurement system that measures position information of the moving body based on an output of the head is used. On the measurement surface, a grating having at least a periodic direction of the periodic pattern as a periodic direction is disposed,
The measurement method according to claim 9 , wherein the measurement cycle is determined by a pitch of the grating. The measurement method according to claim 9 , wherein the measurement cycle is determined by a wavelength of the measurement light. An exposure method for exposing an object with an energy beam to form a pattern on the object,
The measuring method according to any one of claims 1 to 11 and that measures positional information of the periodic pattern;
Driving a moving body holding the object based on a measurement result of position information of the periodic pattern and exposing the object with the energy beam;
An exposure method comprising: Exposing an object by the exposure method according to claim 12 ;
Developing the exposed object;
A device manufacturing method including: An exposure apparatus that exposes an object with an energy beam to form a device pattern on the object,
A moving body that holds and moves the object;
A position measurement system for measuring the position of the moving body;
A detection system in which at least a part thereof is provided on one of the moving body and the outside of the moving body to detect a pattern or a pattern image;
Measurement information of the position of the moving body measured by the position measuring system while driving the moving body in a periodic direction of a periodic pattern arranged on the other of the moving body and the outside of the moving body, and the cycle A control device that measures position information related to a periodic direction of the periodic pattern based on an output of the detection system that detects a pattern or an image thereof, and
During the measurement, the pitch of the periodic pattern satisfies a predetermined relationship with respect to the measurement cycle of the position measurement system, in which the periodic error of the position measurement system does not cause the measurement error of the position of the periodic pattern ,
The exposure apparatus is an exposure apparatus in which the pitch of the periodic pattern is not a natural number m times the measurement period . The exposure apparatus according to claim 14 , wherein the predetermined relationship is a relationship in which n is a natural number of 2 or more and a pitch of the periodic pattern is equal to (m + 1 / n) times the measurement period. A mask holding member on which the mask on which the device pattern is formed is placed;
An optical system that emits the energy beam through the pattern existing on the mask holding member toward the moving body;
The detection system includes at least a part of the moving body,
Wherein the controller, upon measurement of the positional information about the periodic direction of the periodic pattern, according to claim 14 or 15, received by the periodic pattern and the detection system through the optics present in the mask holding member on Exposure device. The mask holding member is movable at least in the periodic direction;
The control device includes a pitch measurement cycle of the position measurement system of the periodic pattern, so as to satisfy the predetermined relationship, together with the movable body, to claim 16 which drives the mask holding member in the periodic direction The exposure apparatus described. 18. The exposure apparatus according to claim 17 , wherein the control device drives the mask holding member at a speed 1 / (1 + mn) times the driving speed of the moving body, where m is a natural number and n is a natural number of 2 or more. Further comprising another position measurement system for measuring the position of the mask holding member,
The exposure according to claim 17 or 18 , wherein the control device further measures position information related to a periodic direction of the periodic pattern based on measurement information of the position of the mask holding member measured by the another position measurement system. apparatus. The exposure apparatus according to claim 15 , wherein the n is a multiple of four. The exposure apparatus according to any one of claims 15 and 18 to 20 , wherein the periodic pattern includes a number of patterns that are multiples of the n arranged in the periodic direction. The position measurement system includes a head that is provided on one of the moving body and the outside of the moving body, irradiates measurement light on the measurement surface provided on the other, and receives light from the measurement surface; The exposure apparatus according to any one of claims 14 to 21 , wherein position information of the moving body is measured based on an output of the head. On the measurement surface, a grating having at least a periodic direction of the periodic pattern as a periodic direction is disposed,
The exposure apparatus according to claim 22 , wherein the measurement cycle is determined by a pitch of the grating. The exposure apparatus according to claim 22 , wherein the measurement cycle is determined by a wavelength of the measurement light. Wherein the control device, based on the measurement result of the position information of the periodic pattern by driving the movable body that holds the object by the energy beam according to any one of claims 14 to 24 for exposing the object Exposure device.

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