JP2011258922A - Exposure equipment and exposure method, and method of manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To align a wafer and a pattern with high precision.SOLUTION: Position of a stage is measured using a position measurement system, and the stage is driven based on the measurement results. Based on the detection results obtained by detecting an alignment mark of a wafer held on the stage by using an alignment system, and correction information (correction data given for the lattice points mof an ideal lattice) dependent on the position of the stage for the detection results, the stage holding a wafer is driven so that a pattern formed on the wafer is arranged in ideal lattice shape.

Description

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

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

  In this type of exposure apparatus, with the miniaturization of device rules (practical minimum line width) due to high integration of semiconductor elements, higher overlay accuracy (positioning accuracy) has been required. In order to meet such demands, it is necessary to realize measurement with higher accuracy in position measurement of alignment marks (alignment marks) on a substrate such as a wafer or a glass plate, which is a prerequisite for improving overlay accuracy.

  On the other hand, since the projection exposure apparatus is an apparatus used for mass production of microdevices, high throughput is inevitably required. For this reason, for example, in recent exposure apparatuses such as scanners, higher acceleration and higher speed of the substrate stage that holds the substrate and the mask stage that holds the mask are further advanced. The acceleration of the stage is realized by increasing the thrust (electromagnetic force) generated by a linear motor or a planar motor that drives the stage. The generated thrust (electromagnetic force) tends to increase more and more. In such an exposure apparatus using a large thrust or a large motor, it is necessary to take measures against vibration accompanying stage driving. Conventionally, for example, a counter mass using a momentum conservation law (see, for example, Patent Document 1) or vibration outside the apparatus. Measures such as the use of a reaction frame that escapes (for example, see Patent Document 2) and the improvement of the vibration isolator performance have been taken.

  However, recently, particularly in an exposure apparatus using a large thrust or a large motor, for example, between a plurality of shot areas on the substrate, the pattern overlay accuracy differs depending on the position of the shot area on the substrate. It turns out that there is a tendency.

US Pat. No. 6,693,402 US Pat. No. 5,528,118

  The inventor conducted various experiments (including simulation) in order to investigate the main factor of the phenomenon in which the pattern overlay accuracy differs between shot areas in accordance with the position on the substrate, and as a result, the position of the substrate stage was determined. Accordingly, it has been found that the position (detection result) is different even for the same mark formed on the substrate. From this, it can be concluded that the main factor is that the mark detection system is deformed and / or displaced particularly due to the movement of the substrate stage.

  The present invention has been made under the above circumstances. According to the first aspect of the present invention, there is provided an exposure apparatus that exposes an object with an energy beam to form a pattern on the object, and holds and moves the object. And a position measuring system for measuring the position of the moving body, a mark detection system for detecting a mark on the object, and a predetermined positional relationship on the object held on the moving body. The detection results obtained by detecting the positions of the plurality of marks using the mark detection system and the position measurement system are corrected based on correction information depending on the position of the moving body, and the corrected mark positions are obtained. An exposure apparatus is provided that includes a control system that controls movement of the moving body that holds the object when the pattern is formed on the object.

  According to this, the detection results of the positions of the plurality of marks formed on the object in a predetermined positional relationship are corrected based on the correction information depending on the position of the moving body, and the corrected Based on the position of the mark, when the pattern is formed on the object, the movement of the moving body that holds the object is controlled. For this reason, when forming a pattern on an object based on the corrected mark position, which includes a position error including a mark detection error of the mark detection system depending on the position of the moving object, the object (moving object) Is controlled. Therefore, it is possible to form a pattern on the object with high accuracy.

  According to the 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, and the pattern is formed on the object held on a moving body in a predetermined positional relationship. Correction based on the position of the moving body, the detection result detected using the mark detection system for detecting the mark on the object and the position measurement system for measuring the position of the moving body An exposure method comprising: correcting based on information and controlling movement of the moving body that holds the object based on the position of the corrected mark when forming the pattern on the object. Provided.

  According to this, when forming a pattern on an object based on the position of the corrected mark obtained by correcting the position error including the mark detection error of the mark detection system depending on the position of the moving object, the object (movement The position of the body) is controlled. Therefore, it is possible to form a pattern on the object with high accuracy.

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

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. FIG. 7A shows the alignment error in the Y-axis direction with respect to the position on the wafer held by the wafer stage, and FIG. 7B shows Y on an axis parallel to the Y-axis passing through the center of the wafer. It is a figure which shows the alignment error regarding an axial direction. FIG. 8A is a diagram showing a plurality of partitioned areas formed in an ideal grid pattern on the test wafer when the test mark is transferred onto the test wafer by the step-and-repeat method. FIG. 5 is a view showing a plurality of test marks arranged in an ideal lattice pattern on a wafer. It is FIG. (1) for demonstrating wafer alignment. It is FIG. (2) for demonstrating wafer alignment. It is a figure for demonstrating correction | amendment of the position (detection result) of the alignment mark when the position on the design of an alignment mark has shifted | deviated from the position of the lattice point of an ideal lattice. FIG. 12A is a diagram showing an example of actual measurement of alignment error, FIG. 12B is a diagram showing alignment error corrected using correction data in map format, and FIG. 12C is a residual error after correction. FIG. FIG. 13A is a diagram showing an example of actual measurement of alignment error, FIG. 13B is a diagram showing alignment error corrected using correction data in model function format, and FIG. 13C is the residual after correction. It is a figure which shows an error. It is FIG. (1) for demonstrating the operation | movement which calculates | requires the offset about Sec-BCHK and secondary alignment system performed at the lot head. It is FIG. (2) for demonstrating the operation | movement which calculates | requires the offset about Sec-BCHK and secondary alignment system performed at the lot head.

  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. 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 of the projection optical system PL ( It is formed in an area (hereinafter also referred to as an exposure area) IA that is conjugated to the illumination area IAR on the wafer W, which is disposed on the image plane side and has 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 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.

  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 on base board 12 through a clearance of about several μm by a non-contact bearing (not shown), for example, an air bearing, which is fixed to the bottom surface of wafer stage WST. Wafer stage WST has a predetermined stroke in the X-axis direction (the direction orthogonal to the paper surface in FIG. 1) and the Y-axis direction (the left-right direction in the paper surface in FIG. 1) by stage drive system 124 (see FIG. 6) including a linear motor and the like. It can be driven with.

  More specifically, on the floor surface, as shown in the plan view of FIG. 3, a pair of Y axes extending in the Y axis direction on one side and the other side in the X axis direction with the base board 12 interposed therebetween The stators 86 and 87 are arranged at a predetermined interval in the X-axis direction. The Y-axis stators 86 and 87 are constituted by, for example, a magnet unit containing a permanent magnet group composed of a plurality of sets of N-pole magnets and S-pole magnets arranged alternately at predetermined intervals along the Y-axis direction. Yes. The Y-axis stators 86 and 87 are provided with two Y-axis movers 84 and 85 engaged in a non-contact manner. That is, the Y-axis movers 84 and 85 are inserted into the internal spaces of the Y-axis stators 86 and 87 having a U-shaped XZ cross section, respectively. It is supported in a non-contact manner through a clearance of about several μm, for example, through the illustrated air pads. Each of the Y-axis movers 84 and 85 is configured by an armature unit that incorporates, for example, armature coils arranged at predetermined intervals along the Y-axis direction. That is, in the present embodiment, a moving coil type Y-axis linear motor is configured by the Y-axis movable element 84 formed of an armature unit and the Y-axis stator 86 formed of a magnetic pole unit. Similarly, the Y-axis movable element 85 and the Y-axis stator 87 constitute a moving coil type Y-axis linear motor. In the following, each of the two Y-axis linear motors will be appropriately referred to as Y-axis linear motors 84 and 85 using the same reference numerals as the respective movers 84 and 85.

  The movers 84 and 85 of the Y-axis linear motors 84 and 85 are fixed to one end and the other end of an X-axis stator 81 extending in the X-axis direction. Therefore, the X axis stator 81 is driven along the Y axis by the pair of Y axis linear motors 84 and 85.

  The X-axis stator 81 is configured by an armature unit that incorporates, for example, armature coils arranged at predetermined intervals along the X-axis direction.

  The X-axis stator 81 is provided in an inserted state in an opening (not shown) formed in a stage main body 91 (not shown in FIG. 3, refer to FIG. 1) constituting a part of wafer stage WST. Inside the opening of the stage main body 91, for example, a magnet unit MU having a permanent magnet group composed of a plurality of pairs of N-pole magnets and S-pole magnets arranged alternately at predetermined intervals along the X-axis direction ( 7A) is provided. The magnet unit MU (see FIG. 7A) and the X-axis stator 81 constitute a moving magnet type X-axis linear motor that drives the stage body 91 in the X-axis direction.

  In the present embodiment, the linear motor constituting the stage drive system 124 is controlled by the main controller 20 shown in FIG. Each linear motor is not limited to either a moving magnet type or a moving coil type, and can be appropriately selected as necessary.

  Note that the rotation (yawing) of wafer stage WST in the θz direction can be controlled by making the thrust generated by the pair of Y-axis linear motors 84 and 85 slightly different.

  Wafer stage WST includes a stage main body 91 and a wafer table WTB mounted on stage main body 91, as shown in FIG. Wafer table WTB and stage main body 91 are relatively moved in the Z-axis direction, θx direction, and θy direction with respect to base board 12 and X-axis stator 81 by a Z leveling mechanism (including a voice coil motor or the like) (not shown). It is driven minutely. In FIG. 6, the stage drive system 124 is shown including the linear motors and the Z leveling mechanism.

  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 in the center, and a pair of slit plates SL in which aerial image measurement slit patterns are formed on both sides of the reference mark FM in the X-axis direction.

  Corresponding to each slit plate SL, an optical system including a lens and a light receiving element such as a photomultiplier tube (photomultiplier tube (PMT)) are arranged inside wafer table WTB. In other words, wafer table WTB is provided with a pair of aerial image measurement devices 45A and 45B (see FIG. 6) similar to those disclosed in US Patent Application Publication No. 2002/0041377. 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 at a position a predetermined distance away from AX 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, 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) of wafer stage WST (wafer table WTB) in the XY plane is transmitted by main controller 20 to one or both of encoder system 150 and interferometer system 118. , Measured as appropriate. For example, at the time of exposure, an encoder system 150 described later is mainly used. In contrast, for example, during wafer alignment, position information (including rotation information in the θz direction) of wafer stage WST (wafer table WTB) in the XY plane is measured using interferometer system 118. Conversely, the encoder system 150 can be used during exposure and the encoder system can be used during wafer alignment. Of course, interferometer system 118 and encoder system 150 may be used together to measure position information of wafer stage WST (wafer table WTB).

  The exposure apparatus 100 of the present embodiment is provided with a plurality of head units that constitute the encoder system 150.

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 “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, a diffraction interference type encoder head disclosed in US Pat. No. 7,238,931 and US 2008/0088843 is used.

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 wafer W is unloaded at the loading position LP (see FIG. 4), the new wafer W is loaded onto the wafer table WTB at the loading position LP (see FIG. 4), and the reference mark FM on the measurement plate 30 is detected by the primary alignment system AL1 (see FIG. 4). The first half of the Pri-BCHK that stores the result of the detection and the measured values of the encoders 70A to 70D in the memory in association with each other, and uses the alignment systems AL1, AL2 _{1 to} AL2 ₄ for the wafer W. Alignment measurement (wafer alignment), which will be described later, was projected by the projection optical system PL. Processing of the second half of Pri-BCHK that measures the projection image (aerial image) of the pair of measurement marks on the reticle R using the aerial image measurement devices 45A and 45B, and each shot area on the wafer obtained as a result of wafer alignment A series of processing using wafer stage WST, such as exposure of a plurality of shot areas on wafer W by the step-and-scan method based on the position information and the latest alignment system baseline, is executed by main controller 20. Is done. Among these, although the wafer alignment will be described in detail later, the other processes are the same as those of the above-mentioned US Patent Application Publication No. 2008/0088843, and thus detailed description thereof is omitted.

  Next, wafer alignment performed by the exposure apparatus 100 of the present embodiment will be described. In this case, correction of the alignment mark position error (alignment error) is performed prior to the EGA calculation. The alignment mark position error (alignment error) is corrected using the correction data.

  In FIG. 7A, as an example, the distribution on the wafer W of the alignment mark position detection error (position error with respect to the Y-axis direction, which is the scanning direction) obtained by the experiment is shown on the wafer stage WST. Contour lines are displayed on the held wafer W. In FIG. 7A, reference numeral MU denotes a magnet unit included in wafer stage WST.

  FIG. 7B shows a one-dimensional distribution of errors on an axis parallel to the Y axis passing through the center of the wafer W in FIG.

  As is clear from FIGS. 7A and 7B, the alignment error is small at the center of the wafer W (exactly shows a negative error), and each has a large peak (amplitude) around Y = ± 50 mm. About 30 nm). Thereby, it turns out that alignment error originates in the magnetic field of magnet unit MU. It can also be seen that the alignment error does not depend strongly on the X position.

  From FIGS. 7A and 7B, it is easily imagined that it is difficult to obtain the position error of each point by a simple calculation, and means for creating practical correction data for correcting the alignment error. As a result, it can be seen that it is a realistic method to actually measure the alignment error.

Creating the correction data according to this embodiment, the self Unit creating test wafer _{W 0} of the (exposure apparatus 100) using a test is formed on the upper surface of the test wafer _{W 0} marks (alignment systems _AL1, AL2 1 AL24 _{4 includes,} for example, a three-step procedure for measuring a position of a two-dimensional mark detectable by ₄ and calculating correction data using the measurement result.

First, the creation of a test wafer _{W 0.} As a premise, it is assumed that calibration of each interferometer (measurement value of each length measuring axis) of the interferometer system 118 has already been performed.

Main controller 20 loads a bare wafer having a resist layer on the surface thereof onto wafer stage WST, and loads a test reticle having a test mark pattern formed at least at the center of the pattern surface (reticle center) onto reticle stage RST. To do. Here, as a test mark, a cross mark M _ij that is partially extracted and shown in the upper right part in FIG. 8A is used.

  Next, reticle alignment is performed by main controller 20, and reticle stage RST is positioned so that the test mark of reticle center is positioned at the projection center of projection optical system PL (in this embodiment, coincides with optical axis AX). . In addition, the reticle blind is driven by main controller 20, and the illumination area of illumination light IL is limited to a rectangular minute area including the test mark of the reticle center.

Then, the main controller 20, a predetermined step pitch [Delta] d (e.g. 5 mm), perform the exposure by the step-and-repeat method, on the test wafer W _0, to transfer a plurality of test marks. Here, the driving of wafer stage WST in the step-and-repeat method is performed by main controller 20 based on the measurement value of interferometer system 118. As a result, as shown in FIG. 8A, an ideal lattice region in which shot regions s are arranged in a matrix at predetermined intervals Δd (for example, 5 mm) in the XY two-dimensional direction is formed, and each shot region s _ij A test mark M _ij is formed at the center. Accordingly, assuming that there is no exposure error, the test marks M _ij are also arranged in an ideal lattice pattern as in the shot area s _ij (see FIG. 8B). Here, notation the position of each point _{m ij} on ideal lattice corresponding to the test mark _{M ij X ij,} and _{Y ij.}

When the exposure of the test wafer W ₀ is completed, the main controller 20, the test wafer W ₀ on wafer stage WST using the wafer transfer system (not shown), to the coater developer inline (not shown) connected to the exposure apparatus 100 Transport. The test wafer W ₀ is developed by the coater developer, and a resist image of the test marks M _ij arranged in an ideal lattice shape is formed on the test wafer W ₀ (see FIG. 8B). Normally, since an exposure error occurs, the test marks M _ij are arranged in a lattice shape distorted from the ideal lattice. That is, the test mark M _ij is formed at a position shifted from the corresponding point m _ij (position X _ij , Y _ij ) on the corresponding ideal lattice.

Next, the test marks M _ij formed on the test wafer W ₀ are detected using the alignment systems AL1, AL2 _{1 to} AL2 ₄ , and correction data is created using the results.

After development, the main controller 20, the test wafer W _0, again loaded on the wafer stage WST using the wafer transfer system. After loading, drives wafer stage WST based on the measurement values of interferometer system 118, sequentially positioning each of the test wafer W ₀ test mark M _ij formed on within the detection field of the alignment system AL1, each positioning Then, the test mark M _ij is detected, and the detection position of the test mark M _{ij in} the X-axis and Y-axis directions with reference to the index center of the alignment system AL1 is obtained.

Main controller 20 sequentially calculates the detection position of test mark M _ij on the stage coordinate system using the detection result of test mark M _ij and the measurement value of interferometer system 118 at the time of detection, and the corresponding ideal lattice Deviations dX _ij and dY _ij from the upper point m _ij (positions X _ij , Y _ij ) are obtained and stored in an internal memory (not shown) as correction data in association with the test mark M _ij (point m _ij ). .

In this embodiment, since the position of wafer stage WST is measured using interferometer system 118, the measurement result may include an error due to fluctuations in air in the atmosphere. Therefore, main controller 20 determines the average of deviations dX _ij and dY _ij for test mark M _ij and, for example, four test marks adjacent to the test mark, M _{i + 1j} , M _i−1j , M _{ij + 1} , and M _ij−1. The value is obtained, and the average value is stored in the internal memory as the deviations dX _ij and dY _{ij with} respect to the test mark M _ij (position X _ij , Y _ij ). However, in the averaging process, the average value is obtained after removing abnormal values. As is clear from FIGS. 7A and 7B, the alignment error gently depends on the XY position of wafer stage WST. Therefore, main controller 20 fits deviations dX _ij and dY _ij for all test marks M _ij using, for example, an XY two-variable polynomial, and uses the result to deform the wafer from deviations dX _ij and dY _ij. And low-order components (linear, etc.) that change due to input reproducibility are removed.

With the above processing, correction data in the map format for the alignment system AL1, that is, correction data dX _ij = dX (X _ij , Y _ij ) at each of the lattice points m _ij (positions X _ij , Y _ij ) of the ideal lattice on the wafer. ), DY _ij = dY (X _ij , Y _ij ).

Main controller 20 creates correction data for each of alignment systems AL2 _{1 to} AL2 _{4 in} the same manner as the correction data for alignment system AL1 described above. Here, as described above, in the wafer alignment in the exposure apparatus 100 of the present embodiment, the detection ranges of the alignment systems AL1, AL2 _{1 to} AL2 ₄ are divided without overlapping. Therefore, it is preferable to detect the test mark M _ij located in the corresponding detection range using each of the alignment systems AL1, AL2 _{1 to} AL2 ₄ and create correction data using the detection result.

  The creation of the correction data described above can be performed as appropriate, for example, when the exposure apparatus 100 is activated, idle, or at the beginning of a lot.

  Next, wafer alignment performed in the exposure apparatus 100 of the present embodiment will be briefly described with reference to FIGS.

  Of the plurality of shot areas already formed on the wafer W shown in FIG. 9 and FIG. 10, 16 colored shot areas are used as alignment shot areas.

As a premise, the secondary alignment systems AL2 _{1 to} AL2 ₄ are driven by the drive mechanism 60 _n described above, for example, according to shot map data of wafers in a lot, and their positions in the X-axis direction are adjusted in advance. And

  First, main controller 20 positions wafer stage WST at a predetermined position where the center of wafer W is located on reference axis LV. At this time, main controller 20 drives each motor of stage drive system 124 based on the measurement values of interferometer system 118 (X interferometer 127, Y interferometer 16, and Z interferometers 43A and 43B). Thus, wafer stage WST is driven.

Next, main controller 20 moves wafer stage WST by a predetermined distance in the + Y direction based on the measurement value of interferometer system 118 and positions it at the position shown in FIG. Using AL2 ₂ and AL2 ₃ , the alignment marks attached to the three first alignment shot areas are detected almost simultaneously and individually (see the star mark ☆ in FIG. 9), and the above three alignment systems AL1, AL2 ₂ , The detection result of AL2 ₃ and the measurement value of the interferometer system 118 at the time of detection are associated with each other and stored in a memory (not shown).

Next, main controller 20 drives wafer stage WST by a predetermined distance in the + Y direction (the direction indicated by the white arrow in FIG. 9) based on the measurement value of interferometer system 118, as shown in FIG. The five alignment marks AL1 and AL2 _{1 to} AL2 ₄ are used to detect the five alignment marks almost simultaneously and individually (refer to the star mark ☆ in FIG. 10), and the five alignment systems AL1, The detection results of AL2 _{1 to} AL2 ₄ and the measurement values of the interferometer system 118 at the time of detection are associated with each other and stored in a memory (not shown).

Next, main controller 20 drives wafer stage WST by a predetermined distance in the + Y direction based on the measurement value of interferometer system 118, so that five alignment systems AL1, AL2 _{1 to} AL2 ₄ The alignment marks attached to the third alignment shot area are positioned almost simultaneously and individually, and the five alignment marks AL1 and AL2 _{1 to} AL2 ₄ are used to detect the five alignment marks almost simultaneously and individually. The detection results of the five alignment systems AL1, AL2 _{1 to} AL2 ₄ and the measurement values of the interferometer system 118 at the time of detection are associated with each other and stored in a memory (not shown).

Next, main controller 20 moves wafer stage WST by a predetermined distance in the + Y direction based on the measurement value of interferometer system 118 and uses primary alignment system AL1, secondary alignment systems AL2 ₂ and AL2 ₃ to perform wafer processing. Position the alignment marks attached to the three force alignment shot areas on W at positions where they can be detected almost simultaneously and individually, and use the three alignment systems AL1, AL2 ₂ and AL2 ₃ to The detection is performed almost simultaneously and individually, and the detection results of the _three alignment systems AL1, AL2 ₂ and AL2 ₃ are associated with the measurement values of the interferometer system 118 at the time of detection and stored in a memory (not shown).

Then, main controller 20 calculates the positions of the 16 alignment marks using the detection results of the total 16 alignment marks thus obtained and the corresponding measurement values of interferometer system 118. Next, the main controller corrects the positions of the 16 alignment marks AM _k (k = 1 to 16) using the correction data dX _ij and dY _ij . For convenience of explanation, the position of the calculated (detected) alignment mark AM _k (k = 1 to 16) will be denoted as X _k and Y _k below. The formation position (design position) of the alignment mark AM _k may not coincide with the lattice point m _ij on the ideal lattice shown in FIG.

Here, as an example, a case _where the positions (detection results) X _k and Y _k of the alignment marks AM _k are corrected will be described with reference to FIG. The main controller 20 searches for three lattice points m _ij on the ideal lattice close to the positions X _k and Y _k of the detected alignment mark AM _k . _Assume that three lattice points m _{i + 1j + 1} , m _{i + 1j} , and m _{ij + 1} (hereinafter referred to as m ₁ , m ₂ , and m ₃ for convenience) shown in FIG. 11 are found. The positions of the three lattice points m ₁ , m ₂ , m ₃ and the corresponding correction data are respectively expressed as (X ₁ , Y ₁ and dX ₁ , dY ₁ ), (X ₂ , Y ₂ and dX ₂ , dY ₂ ). , (X ₃ , Y ₃ and dX ₃ , dY ₃ ). However, the correction data for the three grid points of the alignment systems AL1, AL2 ₁ AL24 _4, the correction data for the same alignment system used in the detection of the alignment mark AM _k.

Main controller 20 uses correction values dX (X for correcting the positions X _k and Y _k of the detected alignment mark AM _k using the deviations about the _three imaginary lattice points m ₁ , m ₂ and m _{3. k} , Y _k ) and dY (X _k , Y _k ) are _obtained as follows as an example.

_{dX (X, Y) = (} dX (X 1, Y 1) -dX (X 2, Y 2)) / (X 1 -X 2)
× (X− (X ₁ + X ₂ ) / 2)
_{+ (DX (X 1, Y} 1) -dX (X 3, Y 3)) / (Y 1 -Y 3)
× (Y− (Y ₁ + Y ₃ ) / 2)
+ (DX (X ₂ , Y ₂ ) −dX (X ₃ , Y ₃ )) / 2 (1)
_{dY (X, Y) = (} dY (X 1, Y 1) -dY (X 2, Y 2)) / (X 1 -X 2)
× (X− (X ₁ + X ₂ ) / 2)
_{+ (DY (X 1, Y} 1) -dY (X 3, Y 3)) / (Y 1 -Y 3)
× (Y− (Y ₁ + Y ₃ ) / 2)
+ (DY (X ₂ , Y ₂ ) −dY (X ₃ , Y ₃ )) / 2 (2)
The main controller 20 uses the calculated correction values dX (X _k , Y _k ), dY (X _k , Y _k ) to determine the positions X _k , Y _k of the alignment mark AM _k as follows. to correct.

_{X k ← X k -dX (X} k, Y k) (3)
Y _k ← Y _k −dY (X _k , Y _k ) (4)
FIG. 12A shows an example of the alignment error. FIG. 12B shows alignment errors that are corrected by interpolating correction data in map format using equations (1) and (2). FIG. 12C shows the residual error after correction. From these figures, it can be seen that the alignment error can be corrected with good accuracy.

  In addition, not only the interpolation method of Formula (1) and Formula (2) but a Lagrange interpolation method, a B-spline interpolation method, etc. are also employable.

On the other hand, when the formation position (design position) of the alignment mark AM _k coincides with any lattice point m _ij on the ideal lattice shown in FIG. 8B, the main controller 20 It is only necessary to correct the positions X _k and Y _k of the alignment mark AM _k using the correction data dX _ij and dY _ij corresponding to the coincident grid points m _ij . That is, in this case, the above-described interpolation calculation is unnecessary.

The main controller 20, in the same manner as described above, the position _X k other alignment marks AM _k, corrected _{Y k} (detection result), the position of the alignment mark AM _k corrected, secondary alignment systems AL2 _n The interferometer system 118 is subjected to statistical calculation by the EGA method disclosed in, for example, Japanese Patent Application Laid-Open No. 61-44429 (corresponding US Pat. No. 4,780,617) using the baseline. 6 types of wafer error parameters (X-axis direction) representing the arrangement of shot areas on the wafer W on a coordinate system defined by the measurement axes (for example, an XY coordinate system having the optical axis of the projection optical system PL as the origin) And offset (parallel movement) of the wafer (center position) in the Y-axis direction, orthogonality error of the stage coordinate system (or shot arrangement), residual rotation error of the wafer, wafer Together determine the linear expansion and contraction) in the X-axis direction and the Y-axis direction, calculates the array of all the shot areas. Here, the baseline of secondary alignment system AL2 _n, means the relative position of each secondary alignment system AL2 _n relative to the primary alignment system AL1 (detection center of) (detection center of).

Here, the correction data (deviations) dX _ij and dY _ij include not only the alignment error due to the magnetic force of the magnet unit MU but also the exposure error of the test mark M _ij . Therefore, the above-described correction corresponds to correcting the positions X _k and Y _k (detection results) of the alignment marks AM _k so that the shot areas are arranged in an ideal lattice pattern on the wafer by wafer alignment. At the time of exposure, since the wafer stage WST is driven (position control) based on the wafer error parameter obtained from the corrected positions X _k and Y _k of the alignment mark AM _k , the shot areas arranged in an ideal lattice pattern A pattern is transferred to each of the above.

  In the above description, the map format correction data is interpolated to correct the alignment mark detection result. However, instead of this, correction may be performed using a model function. As the model function, for example, the following function dX (X, Y) can be adopted.

dX (X, Y) = Σ ₁ G ₁ (X, Y) + Σ _m f _m x ^m (5)
G _l (X, Y) = a _l exp (− (X−b _l ) ² / 2c _l ² )
^{_{× exp (- (Y-d}} l) 2 / 2e l 2) ... (6)
G _l (X, Y) is a Gaussian function. It is desirable that the number of Gaussian functions and the degree of the polynomial on the right side of Equation (5) are appropriately determined according to the alignment error distribution (see, for example, FIGS. 7A and 7B). Further, instead of the Gaussian function, a more optimal function that reproduces the alignment error can be adopted. A similar function can be adopted for the model function dY (X, Y).

Main controller 20 determines the parameter in equation (5) using the method of least squares using the position (detection result) of test mark M _ij and the measured value of interferometer system 118 at the time of detection. Main controller 20 uses model functions dX (X, Y) and dY (X, Y) including the determined parameters in place of the above-described equations (1) and (2), respectively.

  FIG. 13A shows an example of the alignment error. FIG. 13B shows alignment errors corrected using the model functions dX (X, Y) and dX (X, Y). 13 (C) shows the residual error after correction (the difference between the error shown in FIG. 13 (A) and the error shown in FIG. 13 (B)). As can be seen from (C), the alignment error can be corrected with high accuracy by using the model function.

So far, the case where correction data is created for each of the alignment systems AL1, AL2 _{1 to} AL2 ₄ has been described. However, the present invention is not limited to this, and in the exposure apparatus of the present embodiment, the alignment systems AL1, AL2 _{1 to} AL2 ₄ It is good also as creating the common correction data used by all. In this case, creation of common correction data is performed using one selected alignment system (hereinafter referred to as a reference alignment system), and the common correction data is used when detecting the position of the alignment mark by another alignment system. The position of the detected alignment mark is corrected using the data and the deviation (offset) of the position of the same predetermined mark detected by the other alignment system based on the position of the predetermined mark detected by the reference alignment system. The Here, when the detection result of another alignment system is converted into the detection result of the reference alignment system, the offset is the difference between the converted mark position and the same mark position (detection result) by the reference alignment system. Can be expressed.

In the present embodiment, it is desirable that main controller 20 creates the common correction data using primary alignment system AL1 as an example. The reason is that the first, primary alignment system, in addition to be located in five alignment systems _AL1, AL2 1 AL24 ₄ center, unlike the secondary alignment systems _AL2 1 AL24 _4, so immovable (fixed) It is. The fixed alignment system is always affected by, for example, the same magnetic field distribution, and the same alignment error occurs. That is, the alignment error caused by the change in the magnetic field distribution is also more reproducible (reliability as an error) than the movable alignment system.

  As a second reason, in the exposure apparatus 100 of the present embodiment, for example, as in the exposure apparatus disclosed in US Patent Application Publication No. 2008/0088843, for each lot head, the following secondary alignment system is used. Baseline measurement (hereinafter referred to as Sec-BCHK as appropriate) is performed. During this Sec-BCHK, the wafer table by the interferometer system 118 is used together with or instead of the position measurement of the wafer table WTB by the encoder. This is because the above-described offset can be obtained by measuring the position of the WTB.

Sec-BCHK performed at the lot head is performed as follows. As a premise, the secondary alignment system AL2 _n (n = 1 to 4) is driven by the drive mechanism 60 _n described above, for example, according to shot map data of wafers in a lot, and the position in the X-axis direction is set. Shall.
a. First, as shown in FIG. 14, main controller 20 detects a specific alignment mark on wafer W (process wafer) at the head of the lot by primary alignment system AL1 (see the star mark in FIG. 14), and The detection result, the measurement value of the encoder system 150 at the time of detection, and the measurement value of the interferometer system 118 (X interferometer 127, Y interferometer 16, and Z interferometers 43A and 43B) are stored in the memory in association with each other. In the state of FIG. 14, the position of the wafer table WTB in the XY plane is the X head 66 ₃ (encoder 70D) facing the X scale 39X ₂ and the two Y heads 68 facing the Y scales 39Y ₁ and 39Y _{2. 2} and 67 ₃ (encoders 70E ₁ and 70F ₁ ).

b. Next, the main controller 20 moves wafer stage WST to a predetermined distance in the -X direction, as shown in FIG. 15, a specific alignment mark above was detected by secondary alignment system AL2 ₁ (FIG. 15 in ), And the measurement results of the encoders 70A to 70D and the interferometer system 118 at the time of detection are stored in the memory in association with each other. In the state of FIG. 15, the position of wafer table WTB in the XY plane is as follows: X head 66 ₃ (encoder 70D) facing X scale 39X ₂ and two Y heads 68 facing Y scales 39Y ₁ and 39Y _{2. 1} and 67 ₁ (encoders 70F ₁ and 70E ₁ ).

c. Similarly, main controller 20 sequentially moves wafer stage WST in the + X direction, sequentially detects the specific alignment marks with the remaining secondary alignment systems AL2 ₂ , AL2 ₃ , AL2 ₄ , and the detection results thereof. And the measured values of the encoders 70A to 70D at the time of detection and the measured values of the interferometer system 118 are sequentially associated with each other and stored in the memory.

d. Then, the main controller 20 sends the above a. And the above b. Or calculating the baseline of each secondary alignment system AL2 _n based on the processing result of c. Of the alignment system AL1 and the corresponding measurement value of the interferometer system 118, and b. Alternatively, using the detection result of the alignment system of c and the corresponding measurement value of the interferometer system 118, an offset is obtained for the detection results of the alignment systems AL2 _{1 to} AL2 _{4 with} the detection result of the alignment system AL1 as a reference. Here, various methods for obtaining the offset are conceivable. For example, the position of the specific alignment mark (reference alignment mark position) on the stage coordinate system detected by the alignment system AL1 is calculated based on the detection result of the alignment system AL1 and the measurement value of the corresponding interferometer system 118, The position of the detection center of the alignment system AL1 (detection reference position) is obtained from the reference mark position and the detection result of the alignment system AL1, and this detection reference position; b. Alternatively, from the detection result of the secondary alignment system of c, the detection result of the secondary alignment system is converted into the detection result by the alignment system AL1, and the above-described offset is calculated from the converted detection result and the reference mark position by using the secondary alignment system. Alignment system AL2 _n can be obtained.

In this way, during Sec-BCHK performed at the beginning of the lot, an offset is obtained and updated for each secondary alignment system AL2 _n by adding a little operation without adding a special mark detection operation. can do.

Thus, by using the wafer W (process wafer) at the head of the lot and detecting the same alignment mark on the wafer W by the primary alignment system AL1 and each secondary alignment system AL2 _n , each secondary alignment system AL2 is detected. _Since the baseline of _n is obtained, this process eventually corrects the difference in detection offset between the alignment systems caused by the process. Instead of the alignment mark on the wafer, a mark on wafer stage WST, for example, reference mark FM can be detected to obtain the offset.

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 also done by measuring at the same time.

In this embodiment, only for the primary alignment system AL1, correction data (correction map or correction function) for correcting the alignment error using the test wafer described above is created, and for each Sec-BCHK performed at the lot head, By obtaining the above-described offset for the secondary alignment systems AL2 _{1 to} AL2 ₄ , it is possible to correct the alignment error with high accuracy by the above-described procedure.

  In the present embodiment, main controller 20 may perform interferometer system 118 until wafer alignment including correction of the wafer alignment error described above, and obtains the position of each shot area on wafer W by wafer alignment. After that, that is, after the stage at which the target of wafer stage WST at the time of exposure can be set, position control of wafer stage WST in the XY plane is performed by measuring at least one of interferometer system 118 and encoder system 150. This can be done based on the value. That is, at the time of exposure, the position of wafer stage WST in the XY plane may be controlled based on only the measurement value of encoder system 150, not the measurement value of interferometer system 118.

As described above in detail, according to the exposure apparatus 100 of the present embodiment, the main controller 20 causes the alignment systems AL1, AL2 _{1 to} AL2 ₄ and the interferometer system 118 (or the encoder system 150) to be used during wafer alignment. Are used to detect the positions of a plurality of alignment marks formed on the wafer W, and the detection result is corrected based on correction information depending on the position of the wafer stage WST. Based on the above, when the pattern is formed on the wafer W, the movement of the wafer stage WST holding the wafer W is controlled. Here, as the correction information, correction information for correcting the position (detection result) of the alignment mark so as to form an ideal grid array is used. As a result, in the present embodiment, it is possible to form a pattern of a plurality of layers on the wafer W in an ideal lattice arrangement with high accuracy.

  In the above-described embodiment, the case where the wafer stage WST is driven (position control) based on the measurement result of the position of the wafer stage WST by the interferometer system 118 at the time of wafer alignment has been described. Then, wafer stage WST may be driven based on the measurement result of position of wafer stage WST by encoder system 150. In this case, it is necessary to use the encoder system 150 instead of the interferometer system 118 to create the above-described alignment error correction data and to acquire the test mark position for the creation. However, when preparing the test wafer, the wafer stage WST may be driven based on the measurement result of the encoder system 150, or the wafer stage WST may be driven based on the measurement result of the position of the wafer stage WST by the interferometer system 118. The stage WST may be driven.

For example, the main control is performed when the alignment data AL1, AL2 _{1 to} AL2 ₄ are used to detect the test mark M _ij formed on the test wafer W ₀ and to generate correction data using the detection result. The apparatus 20 loads the test wafer W ₀ onto the wafer table WTB, and then drives the wafer stage WST based on the measurement value of the encoder system 150 to align each of the test marks M _ij formed on the test wafer W _0. sequentially positioned within the detection field of the system AL1, it detects the test mark M _ij for each positioning to determine the detected position of the test mark M _ij in the X-axis and Y-axis directions relative to the index center of alignment system AL1.

Main controller 20 sequentially calculates the detection position of test mark M _ij on the coordinate system determined by the measurement axis of encoder system 150 using the detection result of test mark M _ij and the measurement value of encoder system 150 at the time of detection. Then, deviations dX _ij and dY _ij from the corresponding point m _ij (position X _ij , Y _ij ) on the corresponding ideal lattice are obtained and associated with the test mark M _ij (point m _ij ) as alignment error correction data. Store in an internal memory (not shown).

  However, the encoder system 150 is less affected by air fluctuations in the atmosphere than the interferometer system 118, and errors due to air fluctuations are negligible. Therefore, the averaging process for obtaining the average of the deviations for the plurality of adjacent test marks described above is not essential.

  Here, the correction data may be created in common for all heads, or may be created for each of the head units 62E, 62F, 62B, and 62C. Alternatively, even if there are a plurality of heads belonging to the same head unit, there are individual differences, so that correction data may be created for each head.

At the time of wafer alignment, measurement processing of the same procedure as described above is performed by main controller 20, but at this time, the position of wafer stage WST is measured using encoder system 150 instead of interferometer system 118. The For example, in the state shown in FIG. 9, the interferometer system 118 encoder system 150 in place of, i.e. X scales 39X ₁ X head 66 facing the _second and Y scales 39Y _1, Y heads 68 ₂ respectively opposed to 39Y _2, 67 ₃ (encoders 70D to 70F) are used. Further, for example, in the state shown in FIG. 10, the encoder system 150 instead of the interferometer system 118, that is, the X head 66 ₂ facing the X scale 39X ₂ and the Y head facing the Y scales 39Y ₁ and 39Y ₂ , respectively. 68 ₂ and 67 ₃ (encoders 70D to 70F) are used.

Thus, when performing wafer alignment while measuring the position of wafer stage WST using encoder system 150, three encoder heads are used simultaneously. Therefore, the correction data described above is used for each set of three encoder heads used simultaneously, for example, the set of heads 66 ₁ , 67 ₃ , and 68 ₂ shown in FIG. 9, and the heads 66 ₂ and 67 ₃ shown in FIG. , to each of the 68 ₂ pair, it is also possible to create.

  Of course, the configuration of each measuring apparatus such as the encoder system described in the above embodiment is merely an example. For example, similarly to the exposure apparatus disclosed in US Patent Application Publication No. 2008/0088843, an encoder head and a surface position sensor head (Z head) are separately provided in the head units 62A and 62C. Alternatively, a single head having the functions of the encoder head and the Z head may be provided instead of the set of the encoder head and the Z head. Further, as the encoder head, not only a one-dimensional head but also a two-dimensional head having a measurement direction in two orthogonal axes in the same plane may be used. In the latter case, the scale is generally a two-dimensional scale.

  In the above embodiment, the encoder system is configured such that the grating portion (Y scale, X scale) is provided on the wafer table (wafer stage), and the X head and the Y head are arranged outside the wafer stage so as to face the lattice portion. 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-described embodiment, the case where the exposure apparatus is a dry-type exposure apparatus that exposes the wafer W without using liquid (water) has been described. As disclosed in US Pat. No. 1,420,298, WO 2004/055803, US Pat. No. 6,952,253, US Patent Application Publication No. 2008/0088843, and the like. The above embodiment can also be applied to an exposure apparatus that forms an immersion space including an optical path of illumination light between the two and exposes the wafer with illumination light through the projection optical system and the liquid in the immersion space.

  In the above-described embodiment, the case where the exposure apparatus is 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 above-described embodiment is applied to a stationary exposure apparatus such as a stepper. May be. The above-described embodiment 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 above embodiment can also be applied to a multi-stage type exposure apparatus having 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 above embodiment 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, 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, it is designed under the exposure wavelength (for example, 13.5 nm) while generating EUV (Extreme Ultraviolet) light in a soft X-ray region (for example, a wavelength region of 5 to 15 nm) using SOR or a plasma laser as a light source. The above-described embodiment can also be applied to an EUV exposure apparatus using an all-reflection reduction optical system and a reflective mask. 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 and exposure method 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.

DESCRIPTION OF SYMBOLS 20 ... Main control apparatus, 50 ... Stage apparatus, 100 ... Exposure apparatus, 124 ... Stage drive system, 150 ... Encoder system, AL1 ... Primary alignment system, AL2 _{1 to} AL2 ₄ ... Secondary alignment system, PL ... Projection optical system, RST ... reticle stage, R ... reticle, W ... wafer, WST ... wafer stage, WTB ... wafer table.

Claims (29)

An exposure apparatus that exposes an object with an energy beam to form a pattern on the object,
A moving body that moves while holding the object;
A position measurement system for measuring the position of the moving body;
A mark detection system for detecting a mark on the object;
A detection result obtained by detecting the positions of a plurality of marks formed in a predetermined positional relationship on the object held on the moving body using the mark detection system and the position measurement system is determined as the position of the moving body. A control system that controls the movement of the movable body that holds the object when forming the pattern on the object based on the corrected mark position based on the correction information that depends on An exposure apparatus comprising   The exposure apparatus according to claim 1, wherein the correction information is information for correcting the detection results of the plurality of marks so as to be detection results along an ideal lattice.   The correction information is obtained by sequentially detecting a plurality of marks formed in a predetermined positional relationship on a reference object held on the moving body by moving the moving body, and the detection result and the position at the time of detection. The position information of each of the plurality of marks is detected based on a detection result of the measurement system, and the position information is created using the detected position information and the predetermined positional relationship. Exposure device.   The correction information obtains a deviation in the formation position of each of the plurality of marks calculated from the detected position information and the predetermined positional relationship, and uses the deviation to cause the deviation among the plurality of marks. The exposure apparatus according to claim 3, wherein the exposure apparatus is created for discrete positions of the moving body at the time of detecting a mark corresponding to.   The exposure apparatus according to claim 4, wherein the correction information is created by using an average of the deviations of the formation positions for each of the plurality of marks and at least one mark adjacent to the marks.   When the pattern is formed on the object, the control system interpolates the correction information about the three discrete positions including the position of the moving body at the time of detection of the mark, thereby the mark. 6. The exposure apparatus according to claim 4, wherein a correction value for the detection result is obtained, and the detection result of the mark is corrected using the correction value.   The correction information obtains a deviation in the formation position of each of the plurality of marks calculated from the detected position information and the predetermined relationship, and uses the deviation in the formation position to detect the plurality of marks. 4. The exposure apparatus according to claim 2, wherein the exposure apparatus is created by determining a parameter of a fitting function that expresses a deviation of the formation position with respect to the position of the moving body at the time.   When the pattern is formed on the object, the control system obtains a correction value corresponding to the position of the moving body when the mark is detected using the fitting function, and uses the correction value to determine the mark. The exposure apparatus according to claim 7, wherein the detection result is corrected. A plurality of the mark detection systems;
The correction information is created for each of the plurality of mark detection systems,
The said control apparatus correct | amends each of the detection result obtained from these several mark detection systems using the said corresponding correction information, when forming the said pattern on the said object. The exposure apparatus according to item. A plurality of the mark detection systems;
The correction information is created for one of the plurality of mark detection systems,
The control device corrects a detection result obtained from the one mark detection system using the correction information when forming the pattern on the object, and the one of the plurality of mark detection systems is corrected. The detection result obtained from the remaining mark detection systems other than the mark detection system is corrected using the correction information and offset information corresponding to each of the remaining mark detection systems. The exposure apparatus described.   The offset information includes the detection results of the remaining mark detection systems among the detection results of detecting the same mark on the moving object or object by each of the plurality of mark detection systems. The exposure apparatus according to claim 10, wherein, when converted into a detection result, the calculated position of the mark is obtained from a deviation from the detection result of the same mark position by the one mark detection system.   The said position measurement system measures the position of the said mobile body by irradiating measurement light to the reflective surface provided in the said mobile body, and receiving the return light from the said measurement surface. An exposure apparatus according to claim 1.   The position measuring system uses at least one head portion provided on one of the moving body and the outside of the moving body, on a measurement surface disposed on the other of the moving body and the outside of the moving body. 12. The measurement light is irradiated to the diffraction grating, the return light from the measurement surface is received, and the position of the moving body with respect to the periodic direction of the diffraction grating is measured. Exposure device. An exposure method for exposing an object with an energy beam to form a pattern on the object,
A mark detection system for detecting a mark on the object, and a position measurement system for measuring the position of the mobile object, the positions of a plurality of marks formed in a predetermined positional relationship on the object held on the mobile object; The detection result detected using is corrected based on correction information depending on the position of the moving body, and when forming the pattern on the object, the object is detected based on the position of the corrected mark. An exposure method comprising controlling movement of the movable body to be held.   The exposure method according to claim 14, wherein the correction information is information for correcting the detection results of the plurality of marks to be detection results along an ideal lattice.   While measuring the position of the moving body using the position measurement system, the moving body is sequentially positioned in accordance with the predetermined relationship, and the energy beam is sent to the reference object on the moving body through a mark pattern for each positioning position. The exposure method according to claim 15, further comprising forming the plurality of marks on the reference object by irradiating the reference object.   The exposure method according to claim 16, wherein in the forming, the moving body is step-driven at a pitch corresponding to the predetermined positional relationship, and the plurality of marks are formed on the reference object for each step driving.   A plurality of marks formed on the reference object held on the moving body are sequentially detected by moving the moving body, and based on the detection result and the detection result of the position measurement system at the time of the detection 18. The method of claim 16, further comprising: detecting position information of each of the plurality of marks, and generating the correction information using the detected position information and the predetermined positional relationship. An exposure method according to 1.   In the creation, a deviation of the respective formation positions of the plurality of marks calculated from the detected position information and the predetermined relationship is obtained, and the deviation of the plurality of marks is calculated using the deviation. The exposure method according to claim 18, wherein the correction information is created for discrete positions of the moving body at the time of detecting a mark corresponding to.   The exposure method according to claim 19, wherein the correction information is created using an average of the deviations of the formation positions for each of the plurality of marks and at least one mark adjacent to the marks.   In the control, when forming the pattern on the object, by interpolating the correction information about the three discrete positions including the position of the moving body at the time of detection of the mark, 21. The exposure method according to claim 19, wherein a correction value for the mark detection result is obtained, and the mark detection result is corrected using the correction value.   In the creation, a displacement of each of the plurality of marks calculated from the detected position information and the predetermined relationship is obtained, and the displacement of the plurality of marks is calculated using the displacement of the formation positions. 19. The exposure method according to claim 18, wherein the correction information is created by determining a parameter of a fitting function that expresses a deviation of the formation position with respect to the position of the moving body at the time of detection.   23. The control according to claim 22, wherein in the control, a correction value corresponding to the position of the moving body at the time of detection of the mark is obtained using the fitting function, and the detection result of the mark is corrected using the correction value. Exposure method. A plurality of the mark detection systems are prepared,
The correction information is created for each of the plurality of mark detection systems,
24. The method according to claim 15, wherein when the pattern is formed on the object, each of the detection results obtained from the plurality of mark detection systems is corrected using the corresponding correction information. The exposure method according to one item. A plurality of the mark detection systems are prepared,
The correction information is created for one of the plurality of mark detection systems,
In the control, when the pattern is formed on the object, a detection result obtained from the one mark detection system is corrected using the correction information, and the first of the plurality of mark detection systems is corrected. The correction result obtained from the remaining mark detection systems other than one mark detection system is corrected using the correction information and offset information corresponding to each of the remaining mark detection systems. An exposure method according to 1.   The offset information includes the detection results of the remaining mark detection systems among the detection results of detecting the same mark on the moving object or object by each of the plurality of mark detection systems. 26. The exposure method according to claim 25, wherein, when converted into a detection result, the calculated mark position is obtained from a deviation from the detection result of the same mark position by the one mark detection system.   27. The position of the moving body is measured according to any one of claims 14 to 26, wherein the position of the moving body is measured by irradiating a reflecting surface provided on the moving body with measurement light and receiving return light from the measuring surface. Exposure method.   Using at least one head portion provided on one of the moving body and the outside of the moving body, irradiating measurement light on a measurement surface provided on the other of the moving body and the outside of the moving body, 27. The exposure method according to any one of claims 14 to 26, wherein a return light from the measurement surface is received and a position of the moving body with respect to a periodic direction of a diffraction grating formed on the surface of the measurement surface is measured. . Using the exposure method according to any one of claims 14 to 28 to form a pattern on an object;
Developing the object on which the pattern is formed;
A device manufacturing method including: