JP2011222921A - Method for measuring optical characteristics and apparatus, as well as exposure method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a configuration of a part of a measuring apparatus disposed on the image plane side of an optical system and measure optical characteristics of the optical system.SOLUTION: A characteristics measuring apparatus 20 comprises: a L&S pattern 21A and an L&S pattern 23A disposed on the object plane and image plane sides of a projection optical system PL; an illumination optical system ILS to illuminate the L&S pattern 21A and through the projection optical system PL the L&S pattern 23A; and a light reception system 30 to receive reflected light from the L&S pattern 23A through the projection optical system PL and the L&S pattern 21A, and imaging characteristics of the projection optical system PL are determined based on detection signals obtained from the light reception system 30 when images of the L&S pattern 21A and the L&S pattern 23A are moved relatively.

Description

  The present invention relates to an optical characteristic measurement technique for measuring optical characteristics such as distortion of a test optical system, and an exposure technique using the optical characteristic measurement technique.

  For example, in a lithography process for manufacturing an electronic device (microdevice) such as a semiconductor device, a pattern of a reticle (or photomask) is transferred to each shot area of a wafer (or glass plate) via a projection optical system. In order to perform exposure, an exposure apparatus such as a batch exposure type or a scanning exposure type is used. These exposure apparatuses are conventionally provided with, for example, an on-body measuring apparatus in order to maintain optical characteristics such as distortion of the projection optical system in a predetermined state.

  For example, as a conventional distortion measurement apparatus, a test reticle having a plurality of line and space patterns (hereinafter referred to as L & S patterns) and a space provided on a wafer stage or a measurement stage and having a light receiving slit. 2. Description of the Related Art A measurement apparatus that includes an image measurement system and obtains the position of each L & S pattern image by scanning an image of the L & S pattern projection optical system with a slit of the aerial image measurement system is known (for example, Patent Document 1). reference).

JP 2002-14005 A

  In recent exposure apparatuses, types of measuring apparatuses or sensors to be mounted on a wafer stage or a measuring stage are increasing. Therefore, in order to suppress the complexity or enlargement of the configuration of the wafer stage or the measurement stage, the main body (for example, the light receiving unit) of the measurement device that measures various optical characteristics is placed on the object plane side of the projection optical system, for example, It is desirable to simplify (miniaturize) as much as possible the portion disposed on the reticle stage and disposed on the image plane side of the projection optical system.

  The present invention has been made in view of such a problem, and an object of the present invention is to simplify the configuration of a portion of the measuring device disposed on the image plane side of the optical system and measure the optical characteristics of the optical system.

  According to the first aspect of the present invention, there is provided an optical characteristic measuring device that measures the optical characteristic of an optical system that forms an image of a pattern of a first surface on a second surface. The optical characteristic measuring apparatus includes a first periodic pattern disposed on the first surface side, a second periodic pattern disposed on the second surface side, the first periodic pattern, and the An illumination system that illuminates the second periodic pattern through the optical system, and light reception that receives light reflected by the second periodic pattern through the optical system and the first periodic pattern. A moving device for relatively moving the system, the image of the first periodic pattern by the optical system and the second periodic pattern in the periodic direction of the second periodic pattern, and via the moving device An arithmetic unit for obtaining optical characteristics of the optical system based on a detection signal obtained from the light receiving system when the image of the first periodic pattern and the second periodic pattern are relatively moved in the periodic direction; , Are provided.

According to the second aspect of the present invention, there is provided an exposure apparatus that illuminates a pattern with illumination light from an illumination optical system and exposes an object with the illumination light through the pattern and the projection optical system. This exposure apparatus includes the optical characteristic measuring apparatus of the present invention in order to measure the optical characteristics of the projection optical system, and the illumination optical system also serves as the illumination system of the optical characteristic measuring apparatus.
According to the third aspect of the present invention, there is provided an optical property measuring method for measuring the optical properties of an optical system that forms an image of a pattern on the first surface on the second surface. The optical characteristic measurement method includes a step of illuminating a first periodic pattern disposed on the first surface side and a second periodic pattern disposed on the second surface side via the optical system; The image of the first periodic pattern by the optical system and the second periodic pattern are reflected by the second periodic pattern while relatively moving in the periodic direction of the second periodic pattern. A step of receiving light through the optical system and the first periodic pattern, and an optical characteristic of the optical system is obtained based on a detection signal obtained by receiving the light through the first periodic pattern. A process.

  Moreover, according to the 4th aspect of this invention, the exposure method which illuminates a pattern with illumination light and exposes an object with the illumination light through the pattern and a projection optical system is provided. This exposure method measures the optical characteristics of the projection optical system using the optical characteristic measurement method of the present invention.

  According to the present invention, the second periodic pattern on the second surface side is illuminated from the first surface side via the first periodic pattern and the optical system, and the image of the first periodic pattern and the second periodic pattern are illuminated. By receiving the reflected light from the second periodic pattern through the optical system and the first periodic pattern while relatively moving the periodic pattern in the periodic direction, the first periodic pattern The optical characteristics such as the position and / or contrast on the second surface of the image, and thus the distortion and / or the best focus position can be obtained with high accuracy. At this time, since only the member on which the second periodic pattern is formed needs to be disposed on the second surface (image surface) side, the configuration of the portion disposed on the image surface side of the optical system in the measuring device Can be simplified.

1 is a partially cutaway view showing a schematic configuration of an exposure apparatus as an example of an embodiment. (A) is a partially cutaway view showing the characteristic measuring apparatus 20 that is measuring the imaging characteristics of the projection optical system PL, and (B) shows the first L & S pattern 21A in FIG. 2 (A). An enlarged plan view, (C) is an enlarged plan view showing a second L & S pattern 23A in FIG. 2 (A). It is a perspective view which shows the principal part of the characteristic measuring apparatus 20 of FIG. (A) is a figure which shows an example of the intensity distribution of the image of L & S pattern 21A-21C, (B) is an example of the intensity distribution of the light which permeate | transmits L & S pattern 21A-21C among the reflected light from L & S pattern 23A-23C. FIG. (A) is a figure which shows intensity distribution of the reflected light which permeate | transmits L & S pattern 21A-21C when the reference member 22 is moved, (B) permeate | transmits L & S pattern 21A-21C when the reference member 22 is moved further. It is a figure which shows intensity distribution of reflected light. (A), (B), and (C) are diagrams showing changes in detection signals DS1, D2, and DS3 obtained when the reference member 22 is moved in the X direction, and (D) is a diagram showing the reference member 22 in the Z direction. It is a figure which shows the change of detection signal DS2 obtained when it moves to X direction after moving. It is a figure which shows the change of the intensity distribution of the image of L & S pattern 21A-21C formed on the reference member 22, when the reference member 22 is moved to a Z direction. 4 is a flowchart illustrating an example of a measurement operation using the characteristic measurement device 20. (A) is an enlarged view showing two L & S patterns on the object plane side of the modification of the embodiment, and (B) is an enlarged view showing two L & S patterns on the image plane side of the modification of the embodiment.

Hereinafter, an exemplary embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of an exposure apparatus EX of the present embodiment. In FIG. 1, an exposure apparatus EX includes an exposure light source 1, an illumination optical system ILS that illuminates a pattern surface of a reticle R (mask) with exposure illumination light IL (exposure light) from the exposure light source 1, and a reticle R. Reticle stage RST that holds and moves, projection optical system PL that projects a pattern image of the pattern surface (object surface) onto the surface (image surface) of wafer W, and wafer stage WST that moves while holding wafer W And a main control system 11 comprising a computer for comprehensively controlling the operation of the entire apparatus, and other measuring devices and driving devices. As the exposure light source 1, an ArF excimer laser light source (wavelength 193 nm) is used, but a KrF excimer laser light source (wavelength 248 nm), a mercury lamp, or the like can also be used.

  A substantially linearly polarized illumination light IL emitted from the exposure light source 1 converts a polarization state of the illumination light IL into linearly polarized light or circularly polarized light in a different direction through a known beam transmission system 2. 3 is incident. The illumination light IL that has passed through the polarization state varying unit 3 is incident on a micro fly's eye lens (or fly eye lens) 5 through a beam shape varying unit 4 for changing the cross-sectional shape of the light beam. A surface light source including a large number of secondary light sources is formed on the exit surface of the micro fly's eye lens 5 (pupil surface of the illumination optical system ILS). Instead of the micro fly's eye lens 5, an optical integrator such as a rod integrator (an internal reflection type integrator) may be used. In addition, a variable aperture stop (not shown) for switching to various illuminations such as normal illumination, annular illumination, dipole illumination, and modified illumination is installed on the pupil plane of the illumination optical system ILS. A diffractive optical element or the like for controlling the light amount distribution of the illumination light IL may be provided together with the variable aperture stop or in place of the variable aperture stop.

  The illumination light IL emitted from the micro fly's eye lens 5 passes through the first relay optical system 6, the reticle blind 7, the second relay optical system 8A, the condenser optical system 8B, and the mirror 9 for bending the optical path, and the reticle R. A rectangular illumination area elongated in the X direction on the pattern surface (lower surface) is illuminated with a uniform illuminance distribution. The illumination optical system ILS includes members from the beam transmission system 2 to the condenser optical system 8B and the mirror 9. The operations of the exposure light source 1, the polarization state variable unit 3, and the beam shape variable unit 4 are controlled by an illumination system control unit in the main control system 11.

  Under the illumination light IL, the pattern in the illumination area of the reticle R is one shot of the wafer W at the projection magnification β (for example, a reduction magnification of 1/4, 1/5, etc.) via the projection optical system PL. Transfer exposure is performed on an exposure area within the area (an area optically conjugate with the illumination area). The wafer W is obtained by applying a photoresist (photosensitive agent) to the surface of a disk-shaped substrate having a diameter of about 200 to 450 mm made of silicon or SOI (silicon on insulator). The projection optical system PL is a refractive system as an example, but a catadioptric system or the like can also be used. Hereinafter, the Z-axis is taken in parallel to the optical axis AX of the projection optical system PL, the X-axis is perpendicular to the plane of FIG. 1 in the plane perpendicular to the Z-axis, and the Y-axis is parallel to the plane of FIG. Take and explain.

  As shown in FIG. 1, predetermined optical members constituting the projection optical system PL, for example, lens elements 14A and 14B, are connected via a lens frame (not shown) and three drive elements 13A and 13B that can expand and contract in the Z direction. Supported by a lens barrel. The imaging characteristic control unit in the main control system 11 drives the drive elements 13A and 13B via the drive system 12, whereby the lens elements 14A and 14B are positioned in the Z direction and parallel to the X axis and the Y axis. The tilt angle around the axis (θx direction and θy direction) can be controlled. As described above, a predetermined imaging characteristic (for example, distortion (including a magnification error)) of the projection optical system PL can be corrected by the imaging characteristic control mechanism including the driving element 13A and the like and the driving system 12. Note that the position and the number of the lens elements 14A and 14B that can be driven can be arbitrarily set according to the imaging characteristics to be controlled.

  Next, the reticle stage RST that sucks and holds the reticle R receives light on the reticle base (not shown) by the stage control system 18 (see FIG. 2A) based on the measurement value of the laser interferometer (not shown). The reticle R is moved in the Y direction in a plane perpendicular to the axis AX, and the position in the X direction and the tilt angle around the Z axis (θz direction) are adjusted. On the other hand, the wafer stage WST that holds the wafer W by suction through a wafer holder (not shown) is based on the measurement value of a laser interferometer (not shown) by the stage control system 18 (see FIG. 2A). A movement in the Y direction and a step movement in the X and Y directions are performed in a plane perpendicular to the optical axis AX on the WB. Further, the wafer stage WST has a focus position (in the optical axis AX direction) of the wafer W in order to focus the surface of the wafer W on the image plane of the projection optical system PL based on a measurement value of an autofocus sensor (not shown). And a Z stage mechanism for controlling the inclination angle in the θx direction and the θy direction is also incorporated.

  At the time of exposure, the alignment of the reticle R and the wafer W is performed by an alignment system (not shown) under the control of the exposure control unit in the main control system 11, and then the polarization state of the illumination light IL by the polarization state variable unit 3 Is set to a predetermined state. Thereafter, light emission from the exposure light source 1 is started, and an image of a part of the pattern of the reticle R is exposed to one shot area of the wafer W via the projection optical system PL, and the reticle R and the wafer W are moved in the Y direction. By moving in synchronism with this, the shot area of the wafer W is scanned and exposed. Thereafter, the light emission of the exposure light source 1 is stopped, and the operation of moving the wafer W stepwise and the scanning exposure operation are repeated, so that the pattern of the reticle R is formed on the entire shot area of the wafer W by the step-and-scan method. The image is transferred.

  Further, when the exposure apparatus EX of the present embodiment is an immersion type as shown in, for example, US Patent Application Publication No. 2005/259234, members on the upper surfaces of the projection optical system PL and wafer stage WST (wafer W Alternatively, a liquid such as pure water is supplied to a local immersion space between the reference member 22) described later and a local immersion mechanism (not shown). When the exposure apparatus EX is a dry type, it is not necessary to provide a local liquid immersion mechanism.

  At the time of exposure by the exposure apparatus EX, the imaging characteristics as the optical characteristics of the projection optical system PL need to be adjusted to a predetermined state. Further, since the imaging characteristics gradually change due to the influence of the irradiation heat of the illumination light IL, for example, the fluctuation amount of the imaging characteristics is estimated based on a fluctuation characteristic model obtained in advance, and the fluctuation amount is corrected (offset). Thus, the imaging characteristic control mechanism is driven. In this case, if there is a slight difference between the estimated value of the amount of variation by the variation characteristic model and the actual amount of variation depending on the illumination conditions, the imaging characteristics may gradually deviate from the allowable range for the predetermined state. . Therefore, for example, it is preferable to periodically measure the amount of fluctuation of the imaging characteristics remaining in the projection optical system PL and drive the imaging characteristic control mechanism so as to correct (cancel) this fluctuation amount. The exposure apparatus EX of the present embodiment is provided with a characteristic measuring apparatus 20 for measuring the distortion and the best focus position (and thus the field curvature) as the remaining fluctuation amount of the imaging characteristic of the projection optical system PL.

The characteristic measuring apparatus 20 includes an illumination optical system ILS as an illumination system that generates illumination light IL for measurement, and a reticle mark fixed at a position close to the reticle R of the reticle stage RST in the Y direction (scanning direction). A plate RFM and a light receiving system 30 supported by the reticle stage RST are provided.
Reticle mark plate RFM has a transmission line and space pattern (hereinafter referred to as an L & S pattern) 21A having a predetermined period in the X direction formed on a surface (one surface) fixed to reticle stage RST. The light receiving system 30 is disposed to face the other surface of the reticle mark plate RFM.
Further, the characteristic measuring apparatus 20 is fixed in the vicinity of the wafer W on the upper surface of the wafer stage WST, and a reflective L & S pattern (line and space pattern) 23A having a predetermined period is formed on the surface in the X direction. A reference member 22, a wafer stage WST as an apparatus to which the reference member 22 is attached and moves the reference member 22, and a measurement unit 17 (arithmetic unit) to which a detection signal of the light receiving system 30 is supplied are provided. The measurement unit 17 is also supplied with information on the position of the wafer stage WST in the X and Y directions measured by a laser interferometer (not shown) via the stage control system 18. The measuring unit 17 obtains the imaging characteristics of the projection optical system PL using the detection signal from the light receiving system 30 and the coordinates of the wafer stage WST, and uses the obtained imaging characteristics information to control the imaging characteristics in the main control system 11. Supply to the department.

  The surface (one surface) of the reticle mark plate RFM on which the L & S pattern 21A and the like are formed is set to the same height (Z position) as the pattern surface of the reticle R and, consequently, the object surface of the projection optical system PL. The surface of the reference member 22 is normally set at the same Z position as the surface of the wafer W and eventually the image plane of the projection optical system PL (the plane that has been the best focus position in the measurement so far). The reference member 22 is formed of, for example, a glass plate that transmits the illumination light IL, and an antireflection film for the illumination light IL is formed on a surface thereof, and a metal (high reflectance of the illumination light IL is partially formed on the surface thereof. The L & S pattern 23A and the like are formed by a film of, for example, chrome. An absorption film (or a light shielding film) having a low reflectance with respect to the illumination light IL is formed on the back surface of the reference member 22.

In the present embodiment, the illumination optical system ILS is also used as the illumination system of the characteristic measurement device 20, but a dedicated illumination system may be provided. Reference member 22 may be provided on a measurement stage (not shown) that moves on wafer base WB independently of wafer stage WST.
When measuring the imaging characteristics of the projection optical system PL, by driving the reticle stage RST, as shown in FIG. 2A, a single measurement point in the illumination area of the illumination light IL from the illumination optical system ILS is obtained. The center of the L & S pattern 21A of the reticle mark plate RFM is set. Then, by driving wafer stage WST, the reference member 22 is moved to the -X direction (or + X direction) side with respect to the center of the image (measurement point in the exposure area) of the L & S pattern 21A by the projection optical system PL. An L & S pattern 23A is set.

  As shown in FIG. 2B, the transmissive L & S pattern 21A of the reticle mark plate RFM has a plurality of rectangular opening patterns 21Aa elongated in the Y direction in the X direction with a width P1 / 2 in the X direction in the light shielding film. They are arranged with a period (pitch) P1. As shown in FIG. 2C, the reflective L & S pattern 23A of the reference member 22 has a plurality of rectangular reflection patterns 23Aa elongated in the Y direction with a width P2 / 2 in the X direction with the light transmission portion as a background. It is arranged in the direction with a period P2. The shape of the L & S pattern 23A of the reference member 22 is obtained by reducing the L & S pattern 21A of the reticle mark plate RFM by the projection magnification β (design value) of the projection optical system PL. That is, the shape of the L & S pattern 23A is substantially the same as that of the image 21AP by the projection optical system PL when there is no aberration of the L & S pattern 21A, and the period P2 of the L & S pattern 23A is β times the period P1 of the L & S pattern 21A (β <1) is reduced. The period P2 is, for example, about several hundred nm to several μm, and is about 360 nm or 2 μm as an example.

  In the present embodiment, as shown in FIG. 3, L & S patterns 21B and 21C having the same shape as the L & S pattern 21A are formed on the reticle mark plate RFM at equal intervals in the X direction. Further, L & S patterns 23B and 23C having the same shape as the L & S pattern 23A are formed on the surface of the reference member 22 at equal intervals in the X direction. The arrangement of the L & S patterns 23A to 23C is obtained by reducing the arrangement of the L & S patterns 21A to 21C at a ratio of the projection magnification β of the projection optical system PL. Accordingly, if the distances in the X direction from the center of the L & S pattern 21B to the centers of the L & S patterns 21A and 21C on both sides are XR1 and XR2 (see FIG. 4A), the L & S patterns 23A and 23A on both sides from the center of the L & S pattern 23B are obtained. The distances XW1 and XW2 in the X direction to the center of 23C are as follows using the projection magnification β. In the present embodiment, XR1 = XR2.

XW1 = β · XR1 (1A), XW2 = β · XR2 (1B)
In this embodiment, since the projection optical system PL forms an inverted image as an example, the arrangement of the L & S patterns 23A to 23C is inverted in the X direction with respect to the arrangement of the L & S patterns 21A to 21C. For convenience of explanation, in FIGS. 3 and 4A, etc., only a part of the L & S patterns 21A to 21C and the L & S patterns 23A to 23C are shown enlarged. When measuring the imaging characteristics of the projection optical system PL, as an example, the center of the L & S pattern 21B at the center of the reticle mark plate RFM is on a straight line passing through the optical axis AX of the projection optical system PL and parallel to the Y axis. The L & S patterns 21A and 21C are at positions close to both ends in the X direction within the illumination region.

  In the characteristic measuring apparatus 20, approximately half of the illumination light IL from the illumination optical system ILS illuminates the L & S patterns 21 </ b> A to 21 </ b> C of the reticle mark plate RFM via the half mirror 31. The illumination light ILT that has passed through the L & S patterns 21A to 21C in FIG. 3 is irradiated to the region including the L & S patterns 23A to 23C of the reference member 22 or the vicinity thereof via the projection optical system PL. The reflected light ILR from the surface of the reference member 22 is applied to the reticle mark plate RFM through the projection optical system PL. In FIG. 2A, light reflected by the half mirror 31 (also referred to as reflected light ILR) among the reflected light that has passed through the L & S pattern 21A of the reticle mark plate RFM in the + Z direction is reflected by the condenser lens 32A. Light is received by a photoelectric detector 33A such as a photodiode. A detection signal DS1 from the photoelectric detector 33A is supplied to the measurement unit 17.

  Similarly, in FIG. 3, the reflected light ILR that passes through the other L & S patterns 21B and 21C of the reticle mark plate RFM in the + Z direction and is reflected by the half mirror 31 is also photoelectrically detected through the condenser lenses 32B and 32C, respectively. Light is received by the same photoelectric detectors 33B and 33C as the detector 33A. The detection signals DS2 and DS3 of the photoelectric detectors 33B and 33C are also supplied to the measurement unit 17 in FIG. The light receiving system 30 includes a half mirror 31, condensing lenses 32A to 32C, photoelectric detectors 33A to 33C, and a frame 34 that holds these members and is fixed to the reticle stage RST. In addition, it is also possible to use one large condenser lens instead of the plurality of condenser lenses 32A to 32C.

  Next, the measurement principle of the imaging characteristics of the projection optical system PL using the characteristic measuring device 20 will be described. In FIG. 4A, the illumination light ILT that has passed through the L & S patterns 21A to 21C of the reticle mark plate RFM irradiates the area where the L & S patterns 23A to 23C on the surface of the reference member 22 are formed via the projection optical system PL. This represents a state where images of the L & S patterns 21A to 21C by the projection optical system PL are formed on the L & S patterns 23A to 23C. 4A and FIG. 4B, FIG. 5A, FIG. 5B, and FIG. 7 to be described later, for convenience of explanation, the projection optical system PL is represented by a front view and an L & S pattern 21A. To 21C and L & S patterns 23A to 23C are shown in an enlarged plan view.

  In FIG. 4A, when the projection optical system PL has no aberration, the intensity distribution of the image by the projection optical system PL of the L & S patterns 21A, 21B, and 21C is near the resolution limit of the projection optical system PL. In some cases, sinusoidal intensity distributions 37A, 37B, and 37C indicated by dotted lines are obtained. When the pitch of the L & S patterns 21A, 21B, 21C is wider than the vicinity of the resolution limit, the intensity distribution of the image by the projection optical system PL of the L & S patterns 21A, 21B, 21C is close to a rectangular wave (not shown). When the projection optical system PL has no aberration, the distance in the X direction of the centers of the intensity distributions 37A to 37C is equal to the distance in the X direction of the centers of the L & S patterns 23A to 23C. Then, when some aberration remains in the projection optical system PL and distortion occurs, the centers of the intensity distributions 36A, 36B, and 36C indicated by the solid lines of the images of the L & S patterns 21A, 21B, and 21C are Shifted by Di1, Di2, and Di3 in the X direction with respect to the centers of the intensity distributions 37A, 37B, and 37C when there is no aberration.

  As an example, the center of the central L & S pattern 21B is arranged on the optical axis AX. As a result, the distortion of the image of the central L & S pattern 21B becomes almost zero. Therefore, using the state where the center of the intensity distribution 36B and the center of the L & S pattern 23B are aligned in the X direction as a reference (Di2 = 0), the centers of the L & S patterns 23A and 23C at both ends corresponding to the centers of the intensity distributions 36A and 36C. By obtaining the shift amounts Di1 and Di3 in the X direction, the distortions of the images of the L & S patterns 21A and 21C become Di1 and Di3, respectively. Although the distortions Di1 and Di3 are actually considerably smaller than the period P2 of the L & S patterns 23A to 23C, Di1 and Di3 are shown to be considerably large for easy understanding in FIG.

  In addition, in the intensity distributions 36A to 36C (images of the L & S patterns 21A to 21C), the reflected light from the portions matching the reflective L & S patterns 23A to 23C is transmitted through the projection optical system PL. It returns to the patterns 21A to 21C. At this time, an optical path of light traveling from the L & S patterns 21A to 21C to the reference member 22 via the projection optical system PL, and reflected light from the reference member 22 of the light passes through the projection optical system PL and the L & S patterns 21A to 21C. The optical path when returning to is completely the same regardless of the aberration of the projection optical system PL. Therefore, the total amount of reflected light ILR (the magnitudes of the detection signals DS1 to DS3 of the photoelectric detectors 33A to 33C in FIG. 3) passing through the L & S patterns 21A to 21C in the + Z direction from the projection optical system PL side is L & S. The images of the patterns 21A to 21C (intensity distributions 36A to 36C) and the L & S patterns 23A to 23C are substantially proportional to the total amount of light in the overlapping portion.

  When the distortion as shown in FIG. 4A occurs, the wafer stage WST is driven, and the images of the L & S patterns 21A to 21C are used as reference members as indicated by the arrow 35A in FIG. 4B. When the 22 L & S patterns 23A to 23C are scanned in the + X direction, the detection signals DS1, DS2, and DS3 are generated as shown in FIGS. 6 (A), 6 (B), and 6 (C). The directional position changes in a sine wave shape with the same period as the period P2 of the L & S patterns 23A to 23C. Since the actual distortion is considerably smaller than the period P2, the actual movement range of the reference member 22 in the X direction is a position where the center of the image of the L & S pattern 21B matches the center of the L & S pattern 23B (detection signal DS2 The position may be in the range of about width P2 / 2 with the center at the position where the maximum is.

  During the scanning, when the center of the image (intensity distribution 36A) of the L & S pattern 21A coincides with the center of the L & S pattern 23A in FIG. 4B, the light is reflected by the L & S pattern 23A and passes through the projection optical system PL. The intensity distribution 38A of the reflected light ILR that passes through the L & S pattern 21A substantially corresponds to the maximum intensity portion of the intensity distribution 36A on the image plane, and the detection signal DS1 becomes maximum (see FIG. 6A). The X coordinate of wafer stage WST at this time is assumed to be X1. On the other hand, since the image of the L & S pattern 21B (intensity distribution 36B) and the L & S pattern 23B are shifted from each other by almost ½ period, the intensity distribution 38B of light passing through the L & S pattern 21B out of the reflected light ILR from the L & S pattern 23B. Corresponds to light spreading from the minimum intensity portion of the intensity distribution 36B when the X coordinate of the wafer stage WST is X1, and the detection signal DS2 is minimized (see FIG. 6B). On the other hand, since the image (intensity distribution 36C) of the L & S pattern 21C and the L & S pattern 23C are substantially ¼ cycle shifted, the light passing through the L & S pattern 21C out of the reflected light ILR from the L & S pattern 23C. The intensity distribution 38C corresponds to a part of the intensity distribution 36C that has a width that is approximately ½ of the maximum intensity part, and the detection signal DS3 is lower than the maximum value (see FIG. 6C).

  Thereafter, the reference member 22 is further moved in the + X direction indicated by the arrow 35A, and when the X coordinate of the wafer stage WST becomes X2, as shown in FIG. 5A, an image (intensity distribution 36B) of the center L & S pattern 21B is obtained. ) Coincides with the center of the L & S pattern 23B, the intensity distribution 39B of the reflected light ILR passing through the L & S pattern 21B becomes the maximum intensity portion, and the detection signal DS2 becomes maximum (see FIG. 6B). On the other hand, the intensity distribution 39A of the reflected light ILR reflected by the L & S pattern 23A and passing through the L & S pattern 21A becomes the minimum intensity portion, and the detection signal DS1 becomes the minimum (see FIG. 6A). In addition, the intensity distribution 39C of the light passing through the L & S pattern 21C out of the reflected light ILR from the L & S pattern 23C is a portion having a width that is approximately ½ of the other portion of the maximum intensity, and the detection signal DS3 is less than the minimum value. (See FIG. 6C).

  Further, when the reference member 22 is moved in the + X direction indicated by the arrow 35A and the X coordinate of the wafer stage WST becomes X3, as shown in FIG. 5B, an image of the end L & S pattern 21C (intensity distribution 36C). And the center of the L & S pattern 23C coincide with each other, the intensity distribution 40C of the reflected light ILR passing through the L & S pattern 21C becomes the maximum intensity portion, and the detection signal DS3 becomes maximum (see FIG. 6C). On the other hand, the intensity distributions 40A and 40B of the reflected light ILR reflected by the L & S patterns 23A and 23B and passing through the L & S patterns 21A and 21B are portions having a width approximately half of the maximum intensity portion, and the detection signals DS1 and DS2 Becomes an intermediate level.

  Measurement unit 17 obtains X coordinates X1, X2, and X3 of wafer stage WST when detection signals DS1, DS2, and DS3 shown in FIGS. At this time, the image of the center L & S pattern 21B has almost no distortion, and the positional relationship in the X direction of the L & S patterns 23A to 23C of the reference member 22 in FIG. This is the same as the positional relationship of the images of the L & S patterns 21A to 21C. Therefore, with reference to the position X2 when the detection signal DS2 becomes the maximum value, the difference between the position X1 (position X3) and the position X2 when the detection signal DS1 (DS3) becomes the maximum value is the L & S pattern 21A (21C ) Image distortion Di1 (Di3). That is, the measurement unit 17 can calculate the distortions Di1 and Di3 from the following equation.

Di1 = X1-X2 (2A), Di3 = X3-X2 (2B)
Further, in FIG. 7, when the position Z21 in the Z direction on the surface where the L & S patterns 23A to 23C of the reference member 22 are formed is the best focus position of the projection optical system PL, the L & S patterns 21A to 21A of the reticle mark plate RFM. The intensity distributions 36A to 36C of the 21C image have the maximum contrast. When the surface of the reference member 22 is raised to the position Z23 in the + Z direction from the best focus position, the contrast of the image intensity distributions 36A1 to 36C1 of the L & S patterns 21A to 21C is lowered. Conversely, even if the surface of the reference member 22 is lowered from the best focus position to the position Z33 in the −Z direction, the contrast of the image intensity distributions 36A2 to 36C2 of the L & S patterns 21A to 21C is lowered.

  Thus, when the contrast of the intensity distributions 36A to 36C decreases, the contrast of the detection signals DS1 to DS3 obtained by moving the reference member 22 in the X direction also decreases. For example, the detection signal DS2 of reflected light reflected by the central L & S pattern 23B and passing through the L & S pattern 21B in the + Z direction has the best Z position of the reference member 22 as shown by the curves C1 to C4 in FIG. As the focus position Z21 gradually decreases (or increases) to the positions Z22, Z23, and Z24, the contrast (= amplitude / DC component) decreases. Therefore, in the present embodiment, when the reference member 22 is moved in the Z direction and then the reference member 22 is moved in the X direction to capture the detection signals DS1 to DS3, the contrast of the detection signals DS1 to DS3 is maximized. By obtaining the Z position for each signal, the best focus position for each L & S pattern 23A to 23C (each measurement point) of the reference member 22 can be obtained.

  Next, during the exposure process using the exposure apparatus EX of FIG. 1, for example, the characteristic measurement apparatus 20 is used to measure the imaging characteristics of the projection optical system PL or the amount of variation thereof periodically (measurement method). One example will be described with reference to the flowchart of FIG. This operation is controlled by the main control system 11. First, in step 111, as shown in FIG. 2A, the reticle stage RST is driven in the Y direction, the light receiving system 30 of the characteristic measuring device 20 is arranged on the object plane of the projection optical system PL, and illumination optics. L & S patterns 21A to 21C of reticle mark plate RFM are arranged in the illumination area of system ILS. In the next step 112, wafer stage WST is driven in the X direction and the Y direction, and the centers of L & S patterns 23A to 23C of reference member 22 are set to the positions of L & S patterns 21A to 21C in the exposure area of the image plane of projection optical system PL. It is arranged at a position shifted in the −X direction with respect to the center (measurement point) of the image, and the Z position of the surface of the reference member 22 (hereinafter simply referred to as the Z position of wafer stage WST) with respect to the best focus position so far To a position (lower limit) that has been lowered by a predetermined amount (an amount that exceeds the assumed maximum fluctuation amount).

  Thereafter, irradiation of the illumination light IL from the illumination optical system ILS is started, and the illumination light ILT that has passed through the half mirror 31 and the L & S patterns 21A to 21C that are part of the illumination light IL is guided to the projection optical system PL (step 113). ). Thereby, the illumination light ILT illuminates the L & S patterns 23 </ b> A to 23 </ b> C of the reference member 22. Then, the reflected light ILR from the L & S patterns 23A to 23C is supplied to the light receiving system 30 via the projection optical system PL and the L & S patterns 21A to 21C (step 114). In this state, wafer stage WST is driven, and reference member 22 is moved (scanned) in the X direction so that L & S patterns 23A to 23C scan the images of L & S patterns 21A to 21C. Corresponding to the above, the detection signals DS1 to DS3 output from the light receiving system 30 are taken into the measuring unit 17 (step 115). Next, the measurement part 17 calculates | requires the X coordinate of the contrast and peak position of detection signal DS1-DS3 for each L & S pattern 21A-21C, and memorize | stores these measured values corresponding to Z position (step 116).

  In the next step 117, if the Z position of wafer stage WST has not reached the upper limit (position exceeding the assumed maximum height after the change of the best focus position), the operation proceeds to step 118, Main control system 11 raises the Z position of wafer stage WST by δZ through stage control system 18. δZ is set according to the measurement accuracy of the best focus position. Thereafter, the operation returns to step 113, and the operations of steps 113 to 116 are repeated to obtain and store the contrast of the detection signals DS1 to DS3 and the X coordinates of the peak positions for each of the L & S patterns 21A to 21C.

  In step 117, when the Z position of wafer stage WST reaches the upper limit, the operation proceeds to step 119. Actually, the reticle stage RST is driven in the Y direction to move the L & S patterns 21A to 21C of the reticle mark plate RFM in the Y direction within the illumination area, and then the operations in steps 112 to 117 are repeated. The contrast of the detection signals DS1 to DS3 and the X coordinate of the peak position are also obtained and stored at the three measurement points in the other columns in the exposure area. By repeating this operation, the contrast of the detection signals DS1 to DS3 and the X coordinate of the peak position are obtained at a plurality of measurement points arranged at predetermined intervals in the Y direction within the exposure area of the projection optical system PL. At this time, the contrast of the detection signal DS2 and the X coordinate (X2) of the peak position are obtained also at a measurement point near the optical axis AX of the projection optical system PL. The X coordinate (X2) is a reference when calculating distortion at other measurement points. Thereafter, the light receiving system 30 and the reticle mark plate RFM are retracted outside the illumination area, and the reference member 22 is also retracted outside the exposure area.

  In step 119, the measurement unit 17 interpolates, for example, the Z position (best focus position) when the contrast of the detection signal (any one of DS1 to DS3) becomes maximum for each of a plurality of measurement points in the exposure region. For example, an average value of the best focus positions of the respective measurement points is set as an average image plane. In this case, the field curvature can be obtained from the best focus position at each measurement point.

  Further, the measurement unit 17 obtains the X coordinate of the wafer stage WST when the detection signal measured at the Z position closest to the best focus position, for example, takes the peak value at each measurement point. The X component (X2) measured for the measurement point near the axis AX is subtracted to obtain the X component of the distortion. Measurement results of these average image plane, field curvature, and distortion X component are supplied to the main control system 11.

  In the next step 120, the imaging characteristic control unit of the main control system 11 corrects the imaging characteristic of the projection optical system PL via the drive system 12 of the imaging characteristic control mechanism so as to cancel the measured distortion. To do. Thereafter, reticle R is loaded onto reticle stage RST (step 121), and an image of the pattern of reticle R is exposed to each shot area of a plurality of wafers sequentially loaded onto wafer stage WST (step 122). At this time, since the imaging characteristics of the projection optical system PL are corrected, the pattern image of the reticle R can always be exposed onto the wafer via the projection optical system PL with high accuracy.

The effects and the like of this embodiment are as follows.
(1) The characteristic measuring device 20 for measuring the imaging characteristics (optical characteristics) of the projection optical system PL (optical system) of the present embodiment is disposed on the object plane (first surface) side of the projection optical system PL. Reticle mark plate RFM on which L & S patterns 21A to 21C (first periodic patterns) are formed, and L & S patterns 23A to 23C (second surfaces) arranged on the image plane (second surface) side of projection optical system PL. (Periodic pattern) formed on the reference member 22, the illumination optical system ILS that illuminates the L & S patterns 23A to 23C via the L & S patterns 21A to 21C and the projection optical system PL, and the light reflected by the L & S patterns 23A to 23C Is received via the projection optical system PL and the L & S patterns 21A to 21C, and the images of the L & S patterns 21A to 21C by the projection optical system PL and the L & S pattern 23. To 23C relative to the X direction (the periodic direction of the L & S patterns 23A to 23C) and a projection optical system based on detection signals DS1 to DS3 obtained from the light receiving system 30 during the relative movement. And a measuring unit 17 for obtaining the imaging characteristics of the PL.

  In addition, a method for measuring the imaging characteristics (optical characteristics) of the projection optical system PL using the characteristic measurement apparatus 20 is based on the L & S patterns 21A to 21C arranged on the object plane side and the projection optical system PL on the image plane side. The step 113 for illuminating the arranged L & S patterns 23A to 23C, and the images of the L & S patterns 21A to 21C by the projection optical system PL and the L & S patterns 23A to 23C are relatively moved in the X direction, and reflected by the L & S patterns 23A to 23C. Steps 114 and 115 for receiving the received light through the projection optical system PL and the L & S patterns 21A to 21C to obtain the detection signals DS1 to DS3, and the connection of the projection optical system based on the obtained detection signals DS1 to DS3. Determining image characteristics 119.

  According to the present embodiment, the reflected light from the L & S patterns 23A to 23C is projected onto the projection optical system PL and the L & S patterns 21A to 21C while relatively moving the images of the L & S patterns 21A to 21C and the L & S patterns 23A to 23C in the periodic direction. And receiving the detection signals DS1 to DS3, the imaging characteristics such as distortion of the images of the L & S patterns 21A to 21C can be obtained with high accuracy from the peak positions and contrasts of the detection signals DS1 to DS3. . At this time, since only the reference member 22 on which the reflective L & S patterns 23A to 23C are formed needs to be arranged on the wafer stage WST on the image plane side, the image plane side of the projection optical system in the characteristic measuring apparatus 20 is used. The structure of the part arrange | positioned to can be simplified.

In the present embodiment, the reference member 22 is moved on the wafer stage WST in order to relatively move the images of the L & S patterns 21A to 21C and the L & S patterns 23A to 23C. Instead, the L & S pattern is moved on the reticle stage RST. The reticle mark plate RFM side on which 21A to 21C are formed may be moved in the X direction.
(2) Further, in the measurement method of the present embodiment, the Z stage mechanism of wafer stage WST causes the images of L & S patterns 21A to 21C and L & S patterns 23A to 23C to be parallel to the optical axis AX of projection optical system PL. And the light reflected by the L & S patterns 23A to 23C while the image of the L & S patterns 21A to 21C and the L & S patterns 23A to 23C are relatively moved in the X direction. Steps 114 and 115 of receiving the light via the L & S patterns 21A to 21C and obtaining the detection signals DS1 to DS3 are repeated. Therefore, the best focus position and field curvature of the projection optical system PL can be obtained from the Z position when the contrast of the detection signals DS1 to DS3 is maximized.

(3) Three pairs of L & S patterns 21A to 21C and L & S patterns 23A to 23C are formed, and the measurement unit 17 obtains imaging characteristics for the three pairs of L & S patterns. Accordingly, since the imaging characteristics of the three measurement points can be obtained by one movement (relative movement) of wafer stage WST, the measurement efficiency is high.
The number of L & S patterns 21A to 21C formed on the reticle mark plate RFM is arbitrary, and only one L & S pattern 21B may be formed on the reticle mark plate RFM. Similarly, the number of L & S patterns 23A to 23C formed on the reference member 22 is arbitrary, and only one L & S pattern 23B may be formed on the reference member 22. When only the L & S pattern 21B and / or only the L & S pattern 23B are provided, the measurement efficiency is lowered, but the L & S pattern 21B and / or the L & S pattern 21B are measured at the reticle stage RST and / or the wafer stage WST, respectively. Alternatively, the measurement may be performed after moving to the vicinity.

  (4) Further, the exposure apparatus EX of the present embodiment illuminates the pattern of the reticle R with the illumination light IL from the illumination optical system ILS, and the wafer W (object) through the pattern and the projection optical system PL with the illumination light IL ) Is provided with a characteristic measuring device 20 for measuring the imaging characteristics of the projection optical system PL, and the illumination optical system ILS is also used as the illumination system of the characteristic measuring device 20.

The exposure method using the exposure apparatus EX is an exposure method in which the pattern of the reticle R is illuminated with the illumination light IL, and the wafer W is exposed with the illumination light IL via the pattern and the projection optical system PL. The imaging characteristic of the projection optical system PL is measured using this method.
According to the present embodiment, the characteristic measurement device 20 can measure the imaging characteristics of the projection optical system PL with high accuracy. Further, since the illumination optical system ILS is also used as the illumination system of the characteristic measuring device 20, it is not necessary to provide a dedicated illumination system. Furthermore, since only the reference member 22 is on the wafer stage WST side in the characteristic measuring apparatus 20, the configuration of the wafer stage WST can be simplified. Therefore, for example, an exposure amount monitor of the illumination light IL and an alignment mark measurement system (aerial image measurement system) of the reticle R can be disposed with sufficient margin on the wafer stage WST.

In the above embodiment, the following modifications are possible.
(1) The L & S patterns 21A to 21C formed on the reticle mark plate RFM of FIG. 2A and the L & S patterns 23A to 23C formed on the reference member 22 are patterns having the X direction as a periodic direction. However, as shown in an enlarged view in FIG. 9A, an L & S pattern 21AY having a periodic direction in the Y direction of the shape obtained by rotating the L & S pattern 21A by 90 ° is formed in the vicinity of the L & S pattern 21A of the reticle mark plate RFM. Further, an L & S pattern having the Y direction as a periodic direction may be formed in the vicinity of the other L & S patterns 21B and 21C. In this case, as shown in an enlarged view in FIG. 9B, in the vicinity of the L & S pattern 23A of the reference member 22, an L & S pattern 23AY having the Y direction of the shape obtained by rotating the L & S pattern 23A by 90 ° as a periodic direction is provided. An L & S pattern having the Y direction as a periodic direction is also formed in the vicinity of the other L & S patterns 23B and 23C. Further, the photoelectric detectors 33A to 33C in FIG. 3 may receive reflected light that has passed through the L & S patterns 21A, 21AY, etc. with the X direction and the Y direction as periodic directions, but have passed through the L & S patterns 21A, 21AY, etc. The reflected light may be received by another photoelectric detector.

  In this modification, in a process corresponding to step 115 in FIG. 8, the reference member 22 is moved in the X direction indicated by the arrow 35A, and an image such as the X-axis L & S pattern 21A is scanned with the X-axis L & S pattern 23A or the like. Then, after the detection signals DS1 to DS3 are captured, the reference member 22 is moved in the Y direction indicated by the arrow 35B, and an image such as the Y-axis L & S pattern 21AY is scanned with the Y-axis L & S pattern 23AY or the like. (DSY1 to DSY3) are taken in. In a process corresponding to step 116, the distortion at each measurement point of the projection optical system PL is performed by performing the processing of the detection signals DS1 to DS3 and the processing of obtaining the contrast of the detection signals DSY1 to DSY3 and the Y coordinate of the peak position. , The best focus position due to the light beam opened in the Y direction of the projection optical system PL, and astigmatism of the projection optical system PL can be obtained.

  (2) In the above embodiment, the L & S patterns 21A to 21C of the reticle mark plate RFM are binary patterns with a light shielding film having a transmittance of approximately 0% as a background. In addition, the L & S patterns 21A to 21C may be halftone patterns with a light shielding film having a predetermined (for example, several percent) transmittance as a background, and the L & S patterns 21A to 21C may be phase shift patterns.

(3) Further, the L & S patterns 21A to 21C may be formed not on the reticle mark plate RFM but on a test reticle R1 that can be exchanged for the reticle R with respect to the reticle stage RST of FIG. In this case, the light receiving system 30 of the characteristic measuring apparatus 20 may be moved above the reticle stage RST by a moving mechanism (not shown).
In the above embodiment, a scanning exposure type exposure apparatus is used as the exposure apparatus. However, the present invention is also applicable to measuring the optical characteristics of the projection optical system of a batch exposure type exposure apparatus such as a stepper. Applicable.

  In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, It can also be widely applied to various devices such as imaging devices (CCDs, etc.), micromachines, MEMS (Microelectromechanical Systems), thin film magnetic heads, and DNA chips, and exposure apparatuses for manufacturing masks themselves.

The present invention not only measures the optical characteristics of the projection optical system of the exposure apparatus, but also various optical devices such as an astronomical telescope, an ophthalmic examination device, or an optical device such as a small camera provided in a portable camera or a cellular phone. The present invention can also be applied in the same way when measuring optical characteristics such as distortion of the system.
As described above, the present invention is not limited to the above-described embodiment, and various configurations can be taken without departing from the gist of the present invention.

  EX ... exposure apparatus, ILS ... illumination optical system, R ... reticle, RFM ... reticle mark plate, PL ... projection optical system, WST ... wafer stage, W ... wafer, 17 ... measurement unit, 20 ... characteristic measurement apparatus, 21A to 21C ... 1st L & S pattern, 22 ... Reference member, 23A-23C ... 2nd L & S pattern, 30 ... Light receiving system

Claims (12)

In an apparatus for measuring optical characteristics of an optical system that forms an image of a pattern on the first surface on the second surface,
A first periodic pattern disposed on the first surface side;
A second periodic pattern disposed on the second surface side;
An illumination system for illuminating the second periodic pattern via the first periodic pattern and the optical system;
A light receiving system that receives light reflected by the second periodic pattern via the optical system and the first periodic pattern;
A moving device for relatively moving an image of the first periodic pattern by the optical system and the second periodic pattern in a periodic direction of the second periodic pattern;
Based on a detection signal obtained from the light receiving system when the image of the first periodic pattern and the second periodic pattern are relatively moved in the periodic direction via the moving device, the optical of the optical system An arithmetic unit for obtaining characteristics;
An optical property measuring device comprising: The moving device has a mechanism for relatively moving the image of the first periodic pattern and the second periodic pattern in a direction parallel to the optical axis of the optical system,
The arithmetic device relatively moves the image of the first periodic pattern and the second periodic pattern in the direction parallel to the optical axis via the moving device, and then moves the image via the moving device. An optical characteristic of the optical system is obtained based on a detection signal obtained from the light receiving system when the image of the first periodic pattern and the second periodic pattern are relatively moved in the periodic direction. The optical characteristic measuring device according to claim 1.   3. The optical characteristic measuring apparatus according to claim 1, wherein a period in the periodic direction of the image of the first periodic pattern is equal to a period of the second periodic pattern. The image of the first periodic pattern includes a first pattern portion having periodicity in a first direction and a second pattern portion having periodicity in a second direction orthogonal to the first direction,
The second periodic pattern includes a third pattern portion having periodicity in the first direction and a fourth pattern portion having periodicity in the second direction,
When the arithmetic device relatively moves the image of the first periodic pattern and the second periodic pattern in the first direction and the second direction via the moving device, The optical characteristic measuring apparatus according to any one of claims 1 to 3, wherein the optical characteristic of the optical system is obtained based on the obtained detection signal. A plurality of pairs of the first and second periodic patterns are formed,
5. The optical characteristic according to claim 1, wherein the arithmetic unit obtains an optical characteristic of the optical system with respect to a plurality of pairs of the first and second periodic patterns. Measuring device.   The light receiving system includes a condensing optical system that condenses light received through the first periodic pattern, and a photoelectric detector that detects light collected by the condensing optical system. The optical characteristic measuring device according to claim 1, wherein In an exposure apparatus that illuminates a pattern with illumination light from an illumination optical system and exposes an object with the illumination light through the pattern and the projection optical system,
In order to measure the optical characteristic of the projection optical system, the optical characteristic measuring device according to any one of claims 1 to 6, comprising:
An exposure apparatus, wherein the illumination optical system also serves as the illumination system of the optical characteristic measuring apparatus. In a method for measuring optical characteristics of an optical system for forming an image of a pattern on a first surface on a second surface,
Illuminating a first periodic pattern disposed on the first surface side and a second periodic pattern disposed on the second surface side via the optical system;
The image of the first periodic pattern by the optical system and the second periodic pattern are reflected by the second periodic pattern while relatively moving in the periodic direction of the second periodic pattern. Receiving light through the optical system and the first periodic pattern;
Obtaining optical characteristics of the optical system based on a detection signal obtained by receiving light through the first periodic pattern;
An optical property measurement method comprising: The step of obtaining the optical characteristics of the optical system includes:
After relatively moving the first periodic pattern image and the second periodic pattern in a direction parallel to the optical axis of the optical system, the first periodic pattern image and the second period 9. The optical characteristic measuring method according to claim 8, wherein an optical characteristic of the optical system is obtained based on a detection signal obtained from the light receiving system when the target pattern is relatively moved in the periodic direction. The image of the first periodic pattern includes a first pattern portion having periodicity in a first direction and a second pattern portion having periodicity in a second direction orthogonal to the first direction,
The second periodic pattern includes a third pattern portion having periodicity in the first direction and a fourth pattern portion having periodicity in the second direction,
The step of obtaining the optical characteristics of the optical system includes:
Based on a detection signal obtained from the light receiving system when the image of the first periodic pattern and the second periodic pattern are relatively moved in the first direction and the second direction. The optical characteristic measuring method according to claim 8 or 9, wherein an optical characteristic is obtained. A plurality of pairs of the first and second periodic patterns are formed,
The step of obtaining the optical characteristics of the optical system includes:
11. The optical characteristic measuring method according to claim 8, wherein the optical characteristic of the optical system is obtained for each of the plurality of pairs of the first and second periodic patterns. 11. In an exposure method of illuminating a pattern with illumination light and exposing an object with the illumination light via the pattern and a projection optical system,
An exposure method, comprising: measuring an optical characteristic of the projection optical system using the optical characteristic measurement method according to any one of claims 8 to 11.

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