JP2011220981A - Optical characteristic measuring method and device, and exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure optical characteristics of an optical system even with high numerical aperture of the optical system.SOLUTION: A characteristic measurement device 20 comprises: a line&space (L&S) pattern 21A and a L&S pattern 23A which are disposed on an object plane and an image plane, respectively, of a projection optical system PL; an illumination light system ILS which illuminates the L&S pattern 21A and illuminates the L&S pattern 23A through the projection optical system PL; a fluorescent film 24 which reduces opening angle of light passing through the L&S pattern 23A; condenser lenses 32A-32E and photoelectric detectors 33A-33E which collect and detect light passing through the fluorescent membrane 24; and a measuring unit 17 which determine the optical characteristics of the projection optical system PL based on a signal detected by condenser lenses 32A-33E.

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.

  As a conventional distortion measurement apparatus, a test reticle on which a first line and space pattern (hereinafter referred to as an L & S pattern) is formed, a second L & S pattern provided on a wafer stage or a measurement stage, There is known a measuring apparatus including a photoelectric detector that detects light that has passed through the first and second L & S patterns. According to this measuring apparatus, the relative misalignment between the two L & S patterns, and hence the distortion of the projection optical system, is obtained from the moire fringes formed by the light that has passed through the first and second L & S patterns. (For example, refer to Patent Document 1).

US Patent Application Publication No. 2005/0122506

  In recent exposure apparatuses, the numerical aperture of the projection optical system has increased due to, for example, the application of a liquid immersion method. When the numerical aperture of the projection optical system is increased in this way, it opens when the light passing through the L & S pattern on the image plane side of the projection optical system is received by the photoelectric detector as in a conventional distortion measurement device. Since light having a large angle (incident angle), that is, light including information on the fine structure cannot be incident on the photoelectric detector, there is a possibility that the distortion of the projection optical system cannot be accurately measured.

  The present invention has been made in view of such problems, and an object of the present invention is to accurately measure the optical characteristics of a test optical system even when the test optical system has a large numerical aperture.

  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 member on which a first periodic pattern is disposed on the first surface, and a second member on which a second periodic pattern is disposed on the second surface. A member, an illumination system that illuminates the second periodic pattern via the first periodic pattern and the optical system, and a numerical aperture that reduces the opening angle of the light that has passed through the second periodic pattern A limiting member, a condensing element that condenses the light that has passed through the numerical aperture limiting member, a photoelectric detector that detects the light collected by the condensing element, and a detection signal obtained from the photoelectric detector And an arithmetic unit that obtains the optical characteristics of the optical system based thereon.

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 illuminates a first periodic pattern disposed on the first surface and a second periodic pattern disposed on the second surface via the optical system, and the second periodic pattern is illuminated by the second periodic pattern. Optical characteristics of the optical system based on the detection signal obtained by reducing the opening angle of the light that has passed through the periodic pattern, condensing the light with the reduced opening angle, and receiving the collected light Is what you want.

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 a fifth aspect of the present invention, there is provided a device manufacturing method comprising: exposing a photosensitive substrate using the exposure apparatus or exposure method of the present invention; and processing the exposed photosensitive substrate. A method is provided.

  According to the present invention, the light passing through the second periodic pattern is determined by the relative positional relationship between the periodic direction and / or the height direction of the image of the first periodic pattern and the second periodic pattern. Since the light amount or the light amount distribution changes, by detecting the light passing through the second periodic pattern, the relative positional relationship, and thus the optical characteristics such as the distortion of the optical system and / or the best focus position are obtained. be able to.

  Furthermore, since the detection is performed by reducing the opening angle of the light that has passed through the second periodic pattern, there is not much information on light having a large opening angle (incident angle) when the numerical aperture of the optical system is large. Not lost. Accordingly, the optical characteristics of the optical system (test optical system) can be accurately measured.

1 is a partially cutaway view showing a schematic configuration of an exposure apparatus as an example of an embodiment. It is the figure in which a part which shows characteristic measuring device 20 which is measuring the image formation characteristic of projection optical system PL was notched. (A) is a plan view showing a plurality of patterns formed on the reticle mark plate RFM of FIG. 2, (B) is an enlarged view showing the L & S pattern 21A in FIG. 3 (A), and (C) is a reference of FIG. FIG. 3D is a plan view showing a plurality of patterns formed on the member 22, FIG. 3D is an enlarged view showing the L & S pattern 23A in FIG. 3C, and FIG. 3E is an enlarged cross section showing the main part of the light receiving system 30 in FIG. FIG. (A) is a figure which shows an example of intensity distribution of the image of L & S pattern 21A-21C, (B) is a figure which shows an example of intensity distribution of the light which permeate | transmitted L & S pattern 23A-23C. (A) is a figure which shows intensity distribution of the light which permeate | transmitted L & S pattern 23A-23C when the reference member 22 is moved, (B) is the light which permeate | transmitted L & S pattern 23A-23C when the reference member 22 was moved further It is a figure which shows intensity distribution. (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. It is a flowchart which shows an example of the manufacturing process of an electronic device.

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. In addition, a KrF excimer laser light source (wavelength 248 nm), a harmonic generation light source of a YAG laser, and a harmonic wave of a solid-state laser (semiconductor laser, etc.) A generator or a mercury lamp can also be used.

  Illumination light IL made of substantially linearly polarized ultraviolet light emitted from the exposure light source 1 is polarized light that converts the polarization state of the illumination light IL into linearly polarized light, circularly polarized light, or the like in a different direction via a known beam transmission system 2. The light enters the state variable unit 3. 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 50R (see FIG. 3A) 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 50W in the area (an area optically conjugate with the illumination area, see FIG. 3C). 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 is placed on the optical axis AX on the reticle base (not shown) by the stage control system 18 (see FIG. 2) based on the measurement value of the laser interferometer (not shown). The reticle R is moved in the Y direction in the vertical plane, and the position in the X direction and the tilt angle around the Z axis (θz direction) are adjusted. On the other hand, wafer stage WST that holds wafer W by suction via a wafer holder (not shown) is placed on wafer base WB by stage control system 18 (see FIG. 2) based on the measurement value of a laser interferometer (not shown). Movement in the Y direction and step movement in the X and Y directions are performed within a plane perpendicular to the optical axis AX. 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). A Z stage mechanism for controlling the Z position and the tilt angle in the θx direction and θy direction is also incorporated.

  The exposure apparatus EX of the present embodiment is of an immersion type as shown in, for example, US Patent Application Publication No. 2005/259234. As shown in FIG. 2, the exposure apparatus EX applies a liquid Lq such as pure water that transmits the illumination light IL to a local immersion space including the optical path of the illumination light IL irradiated to the exposure area of the projection optical system PL. A local liquid immersion device 80 is provided. In FIG. 2, the local liquid immersion device 80 includes a ring-shaped nozzle unit 81 that holds a liquid Lq such as pure water between the lowermost optical element of the projection optical system PL and a member on the upper surface of the wafer stage WST. A liquid supply device 82 and a pipe 83 for supplying the liquid Lq to the nozzle unit 81, and a pipe 85 and a liquid recovery device 86 for recovering the supplied liquid Lq through a filter member 84 provided in the nozzle unit 81 are provided. .

  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, the supply of the liquid Lq by the local liquid immersion device 80 is started, and in FIG. 1, the light emission of the exposure light source 1 is started, and a partial image of the pattern of the reticle R is projected onto the wafer W via the projection optical system PL. By moving the reticle R and the wafer W in synchronization with the Y direction while exposing one shot area, 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.

  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 device 20 is fixed at a position close to the Y direction (scanning direction) with respect to the illumination optical system ILS as an illumination system that generates illumination light IL for measurement and the reticle R of the reticle stage RST. A plurality of transmission type line-and-space patterns (hereinafter referred to as L & S patterns) 21A, 21B, 21C, 21D, and 21E (see FIG. 3A) (see FIG. 3A) on the lower surface are equally spaced in the X direction. Reticle mark plate RFM thus formed and wafer W on the upper surface of wafer stage WST are fixed in the vicinity of wafer W, and a plurality of transmissive L & S patterns (line and space patterns) 23A, 23B, 23C, 23D, 23E (see FIG. 3C) includes a reference member 22 formed at equal intervals in the X direction. In the present embodiment, the number of L & S patterns 23A to 23E is the same as the number of L & S patterns 21A to 21E.

  Further, the characteristic measuring apparatus 20 is a wafer stage WST as an apparatus for driving the reference member 22, and a light receiving system that is disposed on the bottom surface of the reference member 22 in the wafer stage WST and detects light that has passed through the L & S pattern 23A or the like. 30 and a measuring unit 17 (arithmetic unit) to which a detection signal of the light receiving system 30 is supplied. Information about the position of wafer stage WST in the X and Y directions measured by a laser interferometer (not shown) is also supplied to measurement unit 17 via stage control system 18 in FIG. 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 (lower 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 L & S pattern 23A composed of a plurality of opening patterns is formed on the surface of the metal member (for example, chromium) that blocks the illumination light IL. ing. A liquid-repellent film is formed on the surface of the reference member 22 with respect to the liquid for immersion exposure.

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. Further, the reference member 22 and the light receiving system 30 may be provided on a measurement stage (not shown) that moves on the wafer base WB independently of the wafer stage WST.
As shown in FIG. 3A, a plurality of L & S patterns 21A to 21E having a predetermined period in the X direction having the same shape on the reticle mark plate RFM are arranged in the X direction so as to be within the illumination region 50R of the illumination light IL. Has been. As shown in FIG. 3B, in the L & S pattern 21A, a plurality of rectangular opening patterns 21Aa having a width P1 / 2 in the X direction and elongated in the Y direction are arranged in the light shielding film at a period (pitch) P1 in the X direction. Is. Further, as shown in FIG. 3C, the plurality of L & S patterns 23A to 23E having a predetermined period in the X direction on the surface of the reference member 22 are arranged in the X direction so as to be within the exposure region 50W. ing. As shown in FIG. 3D, the L & S pattern 23A is a pattern in which a plurality of rectangular opening patterns 23Aa having a width P2 / 2 in the X direction and elongated in the Y direction are arranged with a period P2 in the X direction with a light shielding film as a background. It is.

  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 the image 21AP of the L & S pattern 21A by the projection optical system PL when there is no aberration, and the period P2 of the L & S pattern 23A is β times (β <1) is reduced. The period P2 is, for example, about several hundred nm to several μm. For example, the period P2 is about 2 μm.

  Further, the interval in the X direction of the L & S patterns 23A to 23E of the reference member 22 is obtained by reducing the interval in the X direction of the L & S patterns 21A to 21E of the reticle mark plate RFM by the projection magnification β (design value) of the projection optical system PL. It is. As an example, the width of the exposure region 50W in the X direction is 26 mm, the width in the Y direction is 8 mm, and the interval between the L & S patterns 23A to 23E in the X direction is about 6 mm.

  As shown in FIG. 2, when measuring the imaging characteristics of the projection optical system PL, the reticle mark plate is placed at a plurality of measurement points in the illumination area of the illumination light IL from the illumination optical system ILS by driving the reticle stage RST. The centers of the RFM L & S patterns 21A to 21E are set. At this time, the center of the central L & S pattern 21C is arranged on the optical axis AX of the projection optical system PL. Then, by driving wafer stage WST, the reference member is positioned in front of the −X direction (or + X direction) side with respect to the center of the image (measurement point in the exposure area) of projection optical system PL of L & S patterns 21A to 21E. The centers of the 22 L & S patterns 23A to 23E are set. In addition, the liquid immersion exposure liquid Lq is supplied between the projection optical system PL and the surface of the reference member 22 by the local liquid immersion device 80 also when measuring the imaging characteristics.

In the characteristic measuring device 20, the illumination light IL from the illumination optical system ILS illuminates the L & S patterns 21A to 21E of the reticle mark plate RFM, and images of the L & S patterns 21A to 21E by the projection optical system PL are the surfaces of the reference member 22, respectively. Are formed in a region including the L & S patterns 23A to 23E or in the vicinity thereof. On the back surface of the reference member 22, a fluorescent film 24 that generates, for example, fluorescent ILF including visible light isotropically by irradiation with illumination light IL that is ultraviolet light is formed. The fluorescent film 24 is formed of, for example, a material obtained by doping a base material of a fluoride (for example, lanthanum fluoride (LaF ₃ )) with an activator (for example, europium (Eu)) selected from a transition metal and a rare earth element. . The concentration of the activator is set, for example, in the range of 1 mol% to 10 mol% as a cation ratio with respect to the fluoride base material, and preferably about 5 mol%. Further, a protective film made of, for example, a silicon dioxide thin film and transmitting the fluorescence is formed so as to cover the surface of the fluorescent film 24.

  Light (transmitted light) that has passed through the reference member 22 through the L & S patterns 23A to 23E on the surface of the reference member 22 is incident on the fluorescent film 24 on the back surface of the reference member 22, and the amount of transmitted light from the fluorescent film 24 Fluorescent ILF is generated almost isotropically with a light amount distribution corresponding to the distribution. A part of the fluorescent ILF generated in the fluorescent film 24 at the part facing the L & S patterns 23A to 23E is respectively photoelectrically detected by the photoelectric detectors 33A, 33B such as photodiodes via the condenser lenses 32A, 32B, 32C, 32D, 32E. Light is received by 33C, 33D, and 33E. Therefore, when the transmitted light having a large numerical aperture (light having a large opening angle) ILT transmitted through the reference member 22 enters the fluorescent film 24, light having a small numerical aperture (a small opening angle) is generated from the fluorescent film 24. Therefore, the fluorescent ILF having a small numerical aperture is reliably received by the photoelectric detectors 33A to 33E. Detection signals DS1, DS2, DS3 and the like from the photoelectric detectors 33A to 33E are supplied to the measurement unit 17. In addition, a boundary portion between the plurality of fluorescence generation portions so that the fluorescence ILF generated in the portion of the fluorescent film 24 facing the L & S patterns 23A to 23E (hereinafter referred to as the fluorescence generation portion) does not affect other portions. A flat light-shielding plate 31 is disposed. The light receiving system 30 includes the fluorescent film 24, the condenser lenses 32 </ b> A to 32 </ b> E, the photoelectric detectors 33 </ b> A to 33 </ b> E, and the light shielding plate 31.

  The numerical aperture NA of the projection optical system PL is, for example, 1.35 during immersion exposure, and the numerical aperture NAcl on the incident side of the condenser lenses 32A to 32E of the light receiving system 30 is 1/10 of the numerical aperture NA of the projection optical system PL. About 1/20, for example, about 0.1. Further, the condenser lenses 32A to 32E are formed on the light receiving surfaces of the photoelectric detectors 33A to 33E by reducing the image of the corresponding fluorescence generation part of the fluorescent film 24 to approximately 1/3.

  FIG. 3E is an enlarged cross-sectional view showing the reference member 22 in a portion where the L & S patterns 23A and 23B of FIG. 2 are formed. In FIG. 3E, the thickness of the reference member 22 is 0.5 mm, for example, and the fluorescent film 24 is thinner than the reference member 22. Further, assuming that the irradiation area on the L & S pattern 23A (same for other L & S patterns 23B and the like) irradiated with the illumination light IL from the projection optical system PL is a circular area having a diameter D1, the diameter D1 is set to 100 μm, for example. In this case, if the numerical aperture of the illumination light IL incident on the reference member 22 is 1.35, the diameter D2 of the irradiation region (fluorescence generation part) on the fluorescent film 24 of the transmitted light ILT transmitted through the reference member 22 is 3 3 mm. Since the magnification of the condenser lens 32A in FIG. 2 is 1/3, the required diameter D3 of the light receiving surface of the photoelectric detector 33A corresponding to the fluorescence generating portion is 1.1 mm. Therefore, it is preferable to use a photoelectric detector having a light receiving surface of 1.1 mm square or more as the photoelectric detector 33A.

In addition, the efficiency of the numerical aperture in terms of air is approximately (0.1 / 1) ² = 0.01, and the fluorescent efficiency in the fluorescent film 24 is about 0.1 to 0.5%. The amount of light received by the photoelectric detector 33A under this condition is, for example, 25 × 1000 from the aperture having a diameter of about 10 μm on the image plane of the projection optical system PL in order to measure the wavefront aberration of the projection optical system PL. The amount of light received by each pixel when receiving light by an image sensor having a number of pixels is approximately 2 to 10 times. Therefore, a detection signal with a high S / N ratio is obtained from the photoelectric detector 33A that receives the fluorescent ILF from the fluorescent film 24. The same applies to the other photoelectric detectors 33B to 33E.

  Next, the measurement principle of the imaging characteristics of the projection optical system PL using the characteristic measuring device 20 will be described. Hereinafter, for convenience of explanation, it is assumed that only three L & S patterns 21A to 21C are formed on the reticle mark plate RFM, and only three L & S patterns 23A to 23C are formed on the reference member 22. 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, assuming that the distance in the X direction from the center of the L & S pattern 21B of the reticle mark plate RFM to the centers of the L & S patterns 21A and 21C on both sides is XR1 and XR2, from the center of the L & S pattern 23B of the reference member 22. The distances XW1, XW2 in the X direction to the centers of the L & S patterns 23A, 23C on both sides 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 FIG. 4A and the like, 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 (actually, the L & S pattern 21C in FIG. 3A) is the light of the projection optical system PL. The other L & S patterns 21A and 21C are on a straight line that passes through the axis AX and is parallel to the Y axis, and are close to both ends in the X direction within the illumination area.

  4A, when the projection optical system PL has no aberration, the intensity distribution of the images of the L & S patterns 21A, 21B, 21C by the projection optical system PL is sinusoidal intensity distributions 37A, 37B, 37C. 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 pattern 23A, Di1 and Di3 are shown to be considerably large in FIG.

  Further, among the light having the intensity distributions 36A to 36C (images of the L & S patterns 21A to 21C), the light (transmitted light) transmitted through the reference member 22 through the respective opening patterns of the L & S patterns 23A to 23C is shown in FIG. The fluorescent ILF is generated from the fluorescent film 24, and the fluorescent ILF is detected by the photoelectric detectors 33A to 33C (actually, the photoelectric detectors 33A to 33E). The magnitudes of the detection signals DS1 to DS3 of the photoelectric detectors 33A to 33C are substantially proportional to the total light amount of the portions of the intensity distributions 36A to 36C that overlap the opening patterns of the L & S patterns 23A to 23C.

  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. More precisely, the detection signals DS1 to DS3 change in a sine wave shape when the period of the L & S patterns 23A to 23C is near the resolution limit of the projection optical system PL. When the period of the L & S patterns 23A to 23C is larger than the resolution limit of the projection optical system PL, the detection signals DS1 to DS3 change in a rectangular wave shape with respect to the position of the wafer stage WST. 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 May be in the range of about width P2 / 2 with the center at the position where the maximum is. When the detection signals DS1 to DS3 are Fourier-analyzed, the number of opening patterns in each of the L & S patterns 23A to 23C is, for example, several 10 and the reference member 22 is moved within a range of several times to 10 times the period P2. May be.

  During the scanning, in FIG. 4B, the X coordinate of the wafer stage WST when the center of the image (intensity distribution 36A) of the L & S pattern 21A and the center of the L & S pattern 23A coincide is assumed to be X1. At this time, the intensity distribution 38A of the light ILT that has passed through the L & S pattern 23A substantially corresponds to the maximum intensity portion of the intensity distribution 36A on the image plane, and the generated fluorescence is also maximized, so that the detection signal DS1 is maximized ( (See FIG. 6A). On the other hand, since the image (intensity distribution 36B) of the L & S pattern 21B 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 23B is in the minimum intensity portion of the intensity distribution 36B. Correspondingly, since the generated fluorescence is also minimized, the detection signal SD2 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 shifted by almost ¼ period, the intensity distribution 38C of the light passing through the L & S pattern 23C is the maximum of the intensity distribution 36C. Corresponding to a portion having a width that is approximately ½ of the intensity portion, 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. ) And the center of the L & S pattern 23B coincide with each other, and the intensity distribution 39B of the light ILT passing through the L & S pattern 23B becomes the maximum intensity portion and the fluorescence becomes maximum, so that the detection signal DS2 becomes maximum (FIG. 6). (See (B)). On the other hand, the intensity distribution 39A of the light passing through the L & S pattern 23A becomes the minimum intensity portion, and the detection signal DS1 becomes the minimum (see FIG. 6A). Further, the intensity distribution 39C of the transmitted light of 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 higher 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, the intensity distribution 40C of the light ILT passing through the L & S pattern 23C 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 light passing through the L & S patterns 23A and 23B are approximately half the width of the maximum intensity part, and the detection signals DS1 and DS2 are at an intermediate level.

  As an example, 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 the light passing through the central L & S pattern 23B is such that the Z position of the reference member 22 gradually moves from the best focus position Z21 to the positions Z22, Z23, Z24 as shown by the curves C1 to C4 in FIG. When it decreases (or increases), 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. 2, the reticle stage RST is driven in the Y direction so that the L & S pattern 21A of the reticle mark plate RFM is within the illumination area of the illumination optical system ILS on the object plane of the projection optical system PL. Place ~ 21E. In the next step 112, wafer stage WST (reference member 22 and light receiving system 30) is driven in the X and Y directions, and the centers of L & S patterns 23A to 23E of reference member 22 are exposed on the image plane of projection optical system PL. It is arranged at a position shifted in the −X direction with respect to the centers (measurement points) of the images of the L & S patterns 21A to 21E in the region, and the Z position of the surface of the reference member 22 (hereinafter simply referred to as the Z position of wafer stage WST). Is set to a position (lower limit) lowered by a predetermined amount (an amount exceeding the assumed maximum fluctuation amount) with respect to the best focus position so far.

  Thereafter, the illumination light IL from the illumination optical system ILS illuminates the L & S patterns 21A to 21E of the reticle mark plate RFM and the L & S patterns 23A to 23E of the reference member 22 through the projection optical system PL (step 113). Thereby, the fluorescent ILF generated from the fluorescent film 24 by the light transmitted through the L & S patterns 23A to 23E of the reference member 22 is received by the photoelectric detectors 33A to 33E of the light receiving system 30 (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 23E scan the images of L & S patterns 21A to 21E. Corresponding to the above, the detection signal DS1 or the like output from the light receiving system 30 is taken into the measuring unit 17 (step 115). Next, the measurement part 17 calculates | requires X coordinate of contrast and peak position, such as detection signal DS1 for each L & S pattern 21A-21E, 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 and the X coordinate of the peak position such as the detection signal DS1 for each of the L & S patterns 21A to 21E.

  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 signal DS1 and the X coordinate of the peak position are also obtained and stored at three measurement points in other columns in the exposure area. By repeating this operation, the contrast of the detection signal DS1 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 DS3 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, reticle mark plate RFM is retracted outside the illumination area, and reference member 22 is also retracted outside the exposure area.

  In step 119, the measurement unit 17 obtains a Z position (best focus position) at which the contrast of the detection signal DS1 or the like is maximized for each of a plurality of measurement points in the exposure region by performing interpolation, for example, The average value of the best focus positions of the measurement points is taken as the 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. An X component of the distortion is obtained by subtracting the X coordinate measured for the measurement point in the vicinity of the axis AX. 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 measurement apparatus 20 (optical characteristic measurement apparatus) of the present embodiment is a combination of the projection optical system PL that forms an image of the reticle R pattern on the object plane (first surface) on the image plane (second surface). This is a device for measuring image characteristics (optical characteristics). The characteristic measuring apparatus 20 includes a reticle mark plate RFM (first member) on which L & S patterns 21A to 21E (first periodic patterns) arranged on the object plane are formed, and an L & S pattern arranged on the image plane. A reference member 22 (second member) on which 23A to 23E (second periodic pattern) are formed, and an illumination optical system ILS that illuminates the L & S patterns 23A to 23E via the L & S patterns 21A to 23E and the projection optical system PL A fluorescent film 24 (numerical aperture limiting member) that reduces the opening angle (numerical aperture) of the light that has passed through the L & S patterns 23A to 23E, condenser lenses 32A to 32E that condense the light that has passed through the fluorescent film 24, Photoelectric detectors 33A to 33E that detect the light collected by the condenser lenses 32A to 32E, and detections obtained from the photoelectric detectors 32A to 33E. And a measuring unit 17 for determining the optical characteristics of the projection optical system PL (computing unit) based on the signal.

  In addition, a method for measuring the imaging characteristics (optical characteristics) of the projection optical system PL using the characteristic measurement device 20 is performed on the image plane via the L & S patterns 21A to 21E and the projection optical system PL arranged on the object plane. Steps 113 and 115 for illuminating the arranged L & S patterns 23A to 23E, steps 114 and 115 for reducing the opening angle of the light passing through the L & S patterns 23A to 23E, and condensing and receiving the light with the reduced opening angle. And steps 116 and 119 for determining the imaging characteristics of the projection optical system PL based on the detection signal DS1 and the like obtained by the light reception.

  According to the present embodiment, the L & S patterns 23A to 23E depend on the relative positional relationship between the images of the L & S patterns 21A to 21E and the L & S patterns 23A to 23E in the periodic direction (X direction) and / or the height direction (Z direction). The amount of light passing through the light or the light amount distribution changes. Therefore, by detecting the light passing through the L & S patterns 23A to 23E, it is possible to obtain the relative positional relationship, and hence the imaging characteristics such as the distortion of the projection optical system PL and / or the best focus position.

Furthermore, since the opening angle of the light that has passed through the L & S patterns 23A to 23E is detected by the fluorescent film 24, information on light having a large opening angle is lost when the numerical aperture of the projection optical system PL is large. Absent. Therefore, it is possible to accurately measure the imaging characteristics of the projection optical system PL.
(2) The characteristic measuring apparatus 20 includes a wafer stage WST (moving apparatus) that relatively moves the reticle mark plate RFM and the reference member 22 in the periodic direction (X direction) of the L & S patterns 23A to 23E. Obtains the imaging characteristics of the projection optical system PL based on detection signals obtained from the photoelectric detectors 33A to 33E when the images of the L & S patterns 21A to 21E and the L & S patterns 23A to 23E are relatively moved in the X direction. Yes. In this case, for example, the distortion of the projection optical system PL can be obtained by obtaining the peak position of each detection signal.

In the present embodiment, the reference member 22 is moved on the wafer stage WST in order to move the images of the L & S patterns 21A to 21E and the L & S patterns 23A to 23E, but instead, the reticle mark is used by the reticle stage RST. The plate RFM side may be moved in the X direction.
(3) Further, in the measurement method of this embodiment, the Z stage mechanism of wafer stage WST causes the images of L & S patterns 21A to 21E and L & S patterns 23A to 23E to be parallel to the optical axis AX of projection optical system PL. , And the L & S patterns 21A to 21E and the L & S patterns 23A to 23E are relatively moved in the X direction while receiving the light passing through the L & S patterns 23A to 23E and the detection signal DS1 and the like. Steps 114 and 115 for obtaining 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 signal DS1 or the like becomes maximum.

(4) Further, five pairs of L & S patterns 21A to 21E and L & S patterns 23A to 23E are formed, and the measurement unit 17 obtains imaging characteristics with respect to the five pairs of L & S patterns. Accordingly, since the imaging characteristics of the five 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 21E formed on the reticle mark plate RFM is arbitrary, and only one L & S pattern 21C may be formed on the reticle mark plate RFM. Similarly, the number of the L & S patterns 23A to 23E formed on the reference member 22 is arbitrary, and only one L & S pattern 23C may be formed on the reference member 22. When only the L & S pattern 21C and / or only the L & S pattern 23C is provided, the measurement efficiency is lowered, but the L & S pattern 21C and / or the L & S pattern 23C 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.

(5) In the present embodiment, the illumination light IL is ultraviolet light, and the fluorescent film 24 that generates fluorescence by irradiation with ultraviolet light is used as a member for reducing the opening angle of the illumination light IL from the projection optical system PL. Has been. In this case, since the fluorescent film 24 is thin, the configuration of the light receiving system 30 does not increase in size or complexity.
As a member for reducing the opening angle of the illumination light IL from the projection optical system PL, a diffusion part (diffusion surface) that diffuses the illumination light IL such as a rubbed glass surface formed on the back surface of the reference member 22, or a diffusion plate May be used.

  (6) 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. Accordingly, the image of the pattern of the reticle R can be exposed to each shot area of the wafer W with high accuracy by correcting the imaging characteristics based on the measurement result. 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.

In the above embodiment, the following modifications are possible.
(1) As shown in FIG. 2, in the light receiving system 30 of the characteristic measuring device 20, the fluorescence generated from the fluorescent film 24 is reflected between the condenser lenses 32A to 32E and the fluorescent film 24 by internal reflection. For example, a cylindrical reflection member 31 having high reflectivity leading to 32E may be provided. Thereby, the fluorescence generated in the fluorescent film 24 can be efficiently received by the photoelectric detectors 33A to 33E.

  (2) The L & S patterns 21A to 21E formed on the reticle mark plate RFM of FIG. 2 and the L & S patterns 23A to 23E 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. The L & S pattern having the Y direction as the periodic direction may also be formed in the vicinity of the other L & S patterns 21B to 21E. 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. The L & S pattern having the Y direction as a periodic direction is also formed in the vicinity of the other L & S patterns 23B to 23E. In addition, the photoelectric detectors 33A to 33E in FIG. 2 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. After capturing the detection signal DS1 and the like, 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 and the detection signal ( DSY1 etc.). In the process corresponding to step 116, the processing of the detection signal DS1 and the like and the processing of obtaining the contrast of the detection signal DSY1 and the Y coordinate of the peak position are performed, so that the distortion Y at each measurement point of the projection optical system PL is obtained. It is possible to obtain the component and the best focus position by the light beam opened in the Y direction of the projection optical system PL, and astigmatism of the projection optical system PL.

  (3) In the above embodiment, the L & S patterns 21A to 21E 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 21E 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 21E may be phase shift patterns.

(4) Further, the L & S patterns 21A to 21E 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.
Further, when an electronic device (or microdevice) such as a semiconductor device is manufactured using the exposure apparatus EX (or exposure method) of the above embodiment, the electronic device has functions and functions of the electronic device as shown in FIG. Step 221 for performing performance design, Step 222 for manufacturing a mask (reticle) based on this design step, Step 223 for manufacturing a substrate (wafer) as a base material of the device and applying a resist, Exposure of the above-described embodiment Substrate processing step 224 including device exposure process (or exposure method) to expose a reticle pattern to a substrate (sensitive substrate), developing the exposed substrate, heating (curing) and etching the developed substrate, and device assembly Steps (including processing processes such as dicing, bonding, and packaging) ) 225, and an inspection step 226, and the like.

Therefore, in this device manufacturing method, the pattern of the photosensitive layer is formed on the substrate using the exposure apparatus or the exposure method of the above embodiment, and the substrate on which the pattern is formed is processed (step 224). Is included. According to the exposure apparatus or the like, since the reticle pattern can be exposed with high accuracy, an electronic device can be manufactured with high accuracy.
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. The present invention can also be applied when measuring the optical characteristics of the projection optical system of a dry exposure type exposure apparatus.

  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 21E ... 1st L & S pattern, 22 ... Reference member, 23A-23E ... 2nd L & S pattern, 30 ... Light receiving system

Claims (16)

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 member formed with a first periodic pattern disposed on the first surface;
A second member formed with a second periodic pattern disposed on the second surface;
An illumination system for illuminating the second periodic pattern via the first periodic pattern and the optical system;
A numerical aperture limiting member that reduces an opening angle of light that has passed through the second periodic pattern;
A condensing element that condenses the light that has passed through the numerical aperture limiting member;
A photoelectric detector for detecting the light collected by the light collecting element;
An arithmetic device for obtaining optical characteristics of the optical system based on a detection signal obtained from the photoelectric detector;
An optical property measuring device comprising: A moving device that relatively moves the first member and the second member in a periodic direction of the second periodic pattern;
The arithmetic unit causes the moving device to cause an image of the first periodic pattern and the second periodic pattern relative to each other in the periodic direction via the first member and the second member. The optical characteristic measuring apparatus according to claim 1, wherein the optical characteristic of the optical system is obtained based on a detection signal obtained from the photoelectric detector when moved. The moving device has a mechanism for relatively moving the first member and the second member in a direction parallel to the optical axis of the optical system,
The arithmetic device causes the moving device to cause the image of the first periodic pattern and the second periodic pattern to be relative to each other in a direction parallel to the optical axis via the first member and the second member. After moving, the optical characteristic of the optical system based on a detection signal obtained from the photoelectric detector 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 2, wherein: The light emitted from the illumination system is ultraviolet light,
4. The optical property measuring apparatus according to claim 1, wherein the numerical aperture limiting member includes a fluorescent film that emits fluorescence when irradiated with the ultraviolet light. 5.   5. The optical characteristic measuring apparatus according to claim 1, wherein the light collecting element includes an inner surface reflecting member that guides light that has passed through the numerical aperture limiting member by inner surface reflection. 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 condensing element and the photoelectric detector are provided in two corresponding to the first pattern portion, the third pattern portion, and the second pattern portion and the fourth pattern portion, respectively. The optical property measuring apparatus according to any one of claims 1 to 5. A plurality of sets of the first and second periodic patterns, the light collecting element, and the photoelectric detector are formed,
7. The optical characteristic according to claim 1, wherein the arithmetic unit obtains an optical characteristic of the optical system for each of a plurality of sets of the first and second periodic patterns. 8. Measuring device. 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 characteristics of the projection optical system, comprising the optical characteristic measuring device according to any one of claims 1 to 7,
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 and a second periodic pattern disposed on the second surface via the optical system;
Reducing the opening angle of the light that has passed through the second periodic pattern;
Condensing the light having a small opening angle,
Obtaining optical characteristics of the optical system based on a detection signal obtained by receiving the condensed light;
An optical property measuring method characterized by the above. When determining the optical characteristics of the optical system,
10. The light having passed through the second periodic pattern is detected by relatively moving the image of the first periodic pattern and the second periodic pattern in the periodic direction. The optical property measuring method described in 1. When determining the optical characteristics of the optical system,
After relatively moving the first periodic pattern image and the second periodic pattern in a direction parallel to the optical axis, the first periodic pattern image and the second periodic pattern The optical characteristic measuring method according to claim 10, wherein light that has passed through the second periodic pattern is detected by relatively moving the sensor 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,
When obtaining the optical characteristics of the optical system, light that has passed through the first pattern portion, the third pattern portion, and the second pattern portion and the fourth pattern portion is detected independently of each other, and the respective optical characteristics are detected. The optical characteristic measuring method according to claim 9, wherein the characteristic is obtained. A plurality of sets of the first and second periodic patterns are formed,
The optical characteristic of the optical system is obtained for each of a plurality of sets of the first and second periodic patterns when the optical characteristic of the optical system is obtained. The optical property measuring method according to item. 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 9 to 13. Exposing a photosensitive substrate using the exposure apparatus according to claim 8;
Processing the exposed photosensitive substrate. Exposing the photosensitive substrate using the exposure method according to claim 14;
Processing the exposed photosensitive substrate.

Images