JP2006258844A - Apparatus for measuring optical characteristics and exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve highly precise measurement of optical characteristics in an apparatus for measuring optical characteristics and in an exposure apparatus. <P>SOLUTION: A wavefront division optical element 94 having a plurality of reflection face areas arranged in one axial direction within a predetermined plane is moved by linear motors LM1, LM2 in another axial direction perpendicular to the one axial direction within the predetermined plane. A detector 95 receives light via a projection optical system PO and the wavefront division optical element and outputs a detection signal containing information relating to the optical characteristics of an objective optical system. Therefore, wavefront aberration can be measured even in an exposure apparatus using light at wavelengths that does not transmit through a glass, and high precision wavefront division optical element can be manufactured since reflection face areas of the wavefront division optical element are not required to be arranged on a two-dimensional plane. Consequently, highly precise measurement of optical characteristics can be achieved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical characteristic measurement apparatus and an exposure apparatus, and more particularly to an optical characteristic measurement apparatus that measures optical characteristics of a test optical system and an exposure apparatus provided with the optical characteristic measurement apparatus.

  Conventionally, in a lithography process for manufacturing a semiconductor element, a liquid crystal display element or the like, a resist or the like is applied to a pattern formed on a mask or a reticle (hereinafter, collectively referred to as “reticle”) via a projection optical system. In addition, an exposure apparatus is used that transfers onto a substrate such as a wafer or glass plate (hereinafter also referred to as “wafer” as appropriate). In recent years, as this type of apparatus, a step-and-repeat type reduction projection exposure apparatus (so-called “stepper”), a step-and-scan type scanning type improved from this stepper, from the viewpoint of emphasizing throughput. A sequential movement type projection exposure apparatus such as an exposure apparatus is mainly used.

In such an exposure apparatus, conventionally, as an illumination light (exposure beam) for exposure, an ultraviolet ray such as an ultraviolet ray (for example, i-line (wavelength 365 nm)) from an ultra-high pressure mercury lamp or an ultraviolet ray such as KrF excimer laser light (wavelength 248 nm). Light was used. Recently, in order to obtain a higher resolution (resolution), an exposure apparatus using vacuum ultraviolet light such as ArF excimer laser light (wavelength 193 nm) or F ₂ laser light (wavelength 157 nm) as an exposure beam has been developed. Yes. As the illumination optical system and projection optical system of these exposure apparatuses, a refractive system or a catadioptric system has been mainly used.

  On the other hand, in order to manufacture a finer semiconductor element or the like, recently, as exposure light, light in a soft X-ray region having a wavelength of about 100 nm or less, that is, extreme ultraviolet light (hereinafter referred to as EUV (Extreme Ultraviolet) light) Development of an EUV exposure apparatus that uses this method is also underway. In this EUV exposure apparatus, since there is no optical material that transmits EUV light at the present time, the illumination optical system and the projection optical system are all constituted by reflective optical elements (mirrors), and the reticle is also a reflective reticle.

  In this type of exposure apparatus, it is important to accurately superimpose and transfer a reduced image of a reticle pattern onto an already formed shot area on a wafer. For this purpose, an image formation state by a projection optical system is desired. It is necessary to adjust the optical characteristics of the projection optical system and the illumination optical system so that the above state is obtained.

  The adjustment of the optical characteristics described above is based on the premise that the optical characteristics of an optical system such as a projection optical system are accurately measured. In recent years, the wavefront, which is a comprehensive aberration, is used as the optical characteristics of the projection optical system. It has become relatively common to measure aberrations.

  By the way, the wavefront aberration of the projection optical system is measured by various measuring devices so-called on-body after the projection optical system is mounted on the body of the exposure apparatus. As one of this type of measuring apparatus, there is known a Shack-Hartmann wavefront aberration measuring instrument that employs a microlens array as a wavefront splitting optical element in a light receiving optical system (for example, Patent Documents). 1).

  However, since the wavefront aberration measuring instrument described in Patent Document 1 and the like employs a microlens array as the wavefront splitting optical element, EUV light does not pass through the microlens array. It cannot be used for the EUV exposure apparatus.

JP 2003-262948 A

  The present invention has been made under the circumstances described above. From the first viewpoint, the present invention is an optical characteristic measuring apparatus that measures the optical characteristics of a test optical system, and is arranged in a uniaxial direction within a predetermined plane. A wavefront splitting optical element having a plurality of reflecting surface regions; a moving mechanism for moving the wavefront splitting optical element in the other axis direction perpendicular to the uniaxial direction within the predetermined plane; the test optical system and the wavefront splitting optics And a detector that receives light through the element and outputs a detection signal including information on the optical characteristics of the optical system to be detected.

  According to this, the wavefront splitting optical element having a plurality of reflecting surface regions arranged in a uniaxial direction within a predetermined plane is moved by the moving mechanism in the other axial direction orthogonal to the uniaxial direction within the predetermined plane, and detected. The instrument receives light through the test optical system and the wavefront splitting optical element, and outputs a detection signal including information on the optical characteristics of the test optical system. For this reason, it is possible to measure wavefront aberration even in an exposure apparatus that uses light of a wavelength that does not transmit through the glass. In addition, since it is not necessary to arrange the reflecting surface area of the wavefront splitting optical element in a two-dimensional plane, it is possible to manufacture a highly accurate wavefront splitting optical element at a low cost and to realize highly accurate optical characteristic measurement. is there.

  According to a second aspect of the present invention, there is provided an exposure apparatus for transferring a pattern formed on a mask onto an object, an illumination optical system for illuminating the mask with illumination light; and the illumination emitted from the mask A projection optical system that projects light onto the object; an object stage that moves two-dimensionally while holding the object; and at least one of the illumination optical system and the projection optical system is the test optical system. And an optical property measuring device of the present invention provided on an object stage.

  According to this, at least one of the illumination optical system that illuminates the mask with the illumination light and the projection optical system that projects the illumination light emitted from the mask onto the object is used as the optical characteristic measurement device of the present invention. Since it is provided on the object stage so as to be a system, even when using light with a wavelength that is short enough not to pass through the glass, the optical characteristics of at least one of the illumination optical system and the projection optical system are highly accurate. Can be measured. For this reason, by adjusting each part based on the measurement result, the pattern formed on the mask can be transferred onto the object with high accuracy. In addition, high-resolution exposure can be realized by using light having a short wavelength.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 schematically shows the overall configuration of an exposure apparatus 10 according to an embodiment. Since the projection optical system PO is used in the exposure apparatus 10 as will be described later, in the following, the optical axis direction of the projection optical system PO is the Z-axis direction, and the plane orthogonal to this is shown in FIG. The description will be made assuming that the left-right direction in the drawing is the Y-axis direction and the direction orthogonal to the drawing is the X-axis direction. The exposure apparatus 10 includes an exposure apparatus main body 60 and a wavefront sensor 90.

  The exposure apparatus main body 60 projects an image of a part of the circuit pattern formed on the reticle R onto the wafer W via the projection optical system PO, while the reticle R and the wafer W are projected onto the projection optical system PO. The entire circuit pattern of the reticle R is transferred to each of a plurality of shot areas on the wafer W by a step-and-scan method by performing relative scanning in a one-dimensional direction (here, the Y-axis direction).

  The exposure apparatus main body 60 emits EUV light (light in the soft X-ray region) as illumination light EL, reflects the illumination light EL from the light source apparatus 12 and reflects a predetermined incident angle, for example, about 50 [mrad]. ] An illumination optical system including a folding mirror M that is bent so as to be incident on the pattern surface of the reticle R (the lower surface in FIG. 1 (the surface on the −Z side)) (note that the folding mirror M is provided inside the lens barrel of the projection optical system PO). Is actually part of the illumination optical system), reticle stage RST for holding reticle R, and illumination light (EUV light) EL reflected by the pattern surface of reticle R on wafer W. A projection optical system PO that projects perpendicularly to the exposure surface (upper surface (+ Z side surface in FIG. 1)), a wafer stage WST that holds the wafer W, and the like are provided.

  As the light source device 12, a laser excitation plasma light source is used as an example. This laser-excited plasma light source irradiates an EUV light generating substance (target) with high-intensity laser light, whereby the target is excited into a high-temperature plasma state and emitted when the target cools down, ultraviolet light, and ultraviolet light. , Visible light, and light in other wavelength ranges. In the present embodiment, it is assumed that EUV light having a wavelength of 5 to 20 nm, for example, a wavelength of 11 nm is mainly used as an exposure beam (illumination light EL).

  The illumination optical system includes an illumination mirror, a wavelength selection window and the like (all not shown), a bending mirror M, and the like. Moreover, the parabolic mirror as a condensing mirror in the light source device 12 also constitutes a part of the illumination optical system. Illumination light EL that is emitted from the light source device 12 and passes through the illumination optical system (EUV light EL reflected by the bending mirror M) illuminates the pattern surface of the reticle R as arc-slit illumination light.

  The illumination system 11 shown in FIG. 4 is configured by the illumination optical system configured as described above and the light source device 12 described above.

  The reticle stage RST is arranged on a reticle stage base 32 arranged along the XY plane, and the reticle stage base is generated by a magnetic levitation force generated by, for example, a magnetic levitation type two-dimensional linear actuator constituting the reticle stage drive system 34. 32 is levitated and supported. The reticle stage RST is driven with a predetermined stroke in the Y-axis direction by the driving force generated by the reticle stage drive system 34, and is also driven in a minute amount in the X-axis direction and the θz direction (rotation direction around the Z axis). It has become. In addition, this reticle stage RST has a Z-axis direction and an inclination direction with respect to the XY plane (the θx direction, which is the rotation direction around the X axis, and the Y axis) by adjusting the magnetic levitation force generated by the reticle stage drive system 34 at a plurality of locations. It can also be driven by a minute amount in the rotation direction (θy direction).

  An electrostatic chuck type (or mechanical chuck type) reticle holder (not shown) is provided on the lower surface side of the reticle stage RST, and the reticle R is held by the reticle holder. As the reticle R, a reflective reticle is used in correspondence with the illumination light EL being EUV light having a wavelength of 11 nm. The reticle R is held by a reticle holder with the pattern surface being the lower surface. The reticle R is made of a thin plate such as a silicon wafer, quartz, or low expansion glass, and a reflective film that reflects EUV light is formed on the surface (pattern surface) on the −Z side. This reflective film is a multilayer film in which about 50 pairs of molybdenum Mo and beryllium Be films are alternately laminated with a period of about 5.5 nm, and this multilayer film is about 70% of EUV light with a wavelength of 11 nm. Has reflectivity. A multilayer film having the same configuration is also formed on the reflecting surfaces of the bending mirror M and other mirrors in the illumination optical system.

  On the multilayer film formed on the pattern surface of the reticle R, for example, nickel Ni or aluminum Al is applied on one surface as an absorption layer, and the absorption layer is patterned to form a circuit pattern.

  The EUV light that hits the part of the reticle R where the absorption layer remains is absorbed by the absorption layer, and the EUV light that hits the reflection film in the part where the absorption layer has been removed (the part from which the absorption layer has been removed). As a result, EUV light (illumination light EL) including circuit pattern information is directed to the projection optical system PO described later as reflected light from the pattern surface of the reticle R.

  The position of reticle stage RST (reticle R) in the stage movement plane (position in the XY plane) is a reticle laser interferometer (projecting a laser beam on a reflective surface provided (or formed) on reticle stage RST). Hereinafter, it is always detected by a resolution of about 0.5 to 1 nm, for example, by 82R) (reticle interferometer). Here, actually, the reticle interferometer is a reticle X interferometer that measures the X-axis direction position (X position) of the reticle stage RST and a reticle Y interference that measures the Y-axis direction position (Y position) of the reticle stage RST. In FIG. 1, these are typically shown as a reticle interferometer 82R. At least one of the reticle Y interferometer and the reticle X interferometer, for example, the reticle Y interferometer, is a two-axis interferometer having two measurement axes, and the reticle stage RST ( In addition to the Y position of reticle R), the rotation amount (yawing amount) in the θz direction (rotation direction about the Z axis) can also be measured.

  The position of the reticle R in the Z-axis direction is composed of a light transmission system 13a that irradiates a detection beam obliquely with respect to the pattern surface, and a light reception system 13b that receives the detection beam reflected by the pattern surface of the reticle R. It is measured by a reticle focus sensor (13a, 13b). As this reticle focus sensor (13a, 13b), for example, a multipoint focal position detection system disclosed in Japanese Patent Laid-Open No. 6-283403 (corresponding US Pat. No. 5,448,332) is used. For this reason, not only the Z position of the pattern surface of the reticle R but also the inclination (rotation amount in the θx and θy directions) with respect to the XY plane can be obtained based on the measurement value of the reticle focus sensor (13a, 13b).

  The measurement values of the reticle interferometer 82R and the reticle focus sensor (13a, 13b) are supplied to a stage controller 70 in the main controller 20 shown in FIG. 4, and the reticle controller 82R and the reticle are supplied by the stage controller 70. The reticle stage RST is driven via the reticle stage drive unit 34 based on the measurement values of the focus sensors (13a, 13b), so that the position and orientation control of the reticle R in the six-dimensional direction is performed. .

  The projection optical system PO has a numerical aperture (NA) of 0.1, for example, and, as will be described later, a reflection optical system composed only of a reflection optical element (mirror) is used. Here, a projection magnification is used. That is 1/4 times larger is used. Accordingly, the EUV light EL that is reflected by the reticle R and includes information on the pattern formed on the reticle R is projected onto the wafer W, whereby the pattern on the reticle R is reduced to ¼ and transferred to the wafer W. Is done.

  The projection optical system PO includes a lens barrel 17 and, for example, six reflective optical elements (mirrors) disposed inside the lens barrel 17. A rectangular opening 17b penetrating vertically is formed in the upper wall (+ Z side wall) of the lens barrel 17a, and an opening 17a is formed in the −Y side wall. Inside the lens barrel 17, a bending mirror M constituting the illumination optical system described above is also arranged.

  Wafer stage WST is arranged on wafer stage base BS arranged along the XY plane, and is levitated and supported on wafer stage base BS by a wafer stage drive system 62 comprising, for example, a magnetic levitation type two-dimensional linear actuator. Yes. Wafer stage WST is driven by wafer stage drive system 62 in the X-axis direction and Y-axis direction with a predetermined stroke (the stroke is, for example, 300 to 400 mm) and in the θz direction (rotation direction about the Z-axis). Is driven by a minute amount. Wafer stage WST is configured to be able to be driven by a minute amount in the Z-axis direction and the tilt direction with respect to the XY plane by wafer stage drive system 62.

  An electrostatic chuck type wafer holder (not shown) is placed on the upper surface of wafer stage WST, and wafer W is attracted and held by the wafer holder. Further, a sensor mounting portion having a shape capable of fitting a wavefront sensor 90 described later is formed on the + Y direction side of wafer stage WST.

  The position of wafer stage WST is always detected by a wafer laser interferometer (hereinafter referred to as “wafer interferometer”) 82W, for example, with a resolution of about 0.5 to 1 nm. In practice, an interferometer having a length measuring axis in the X-axis direction and an interferometer having a length measuring axis in the Y-axis direction are provided. In FIG. 1, these are typically shown as a wafer interferometer 82W. Has been. These interferometers are composed of multi-axis interferometers having a plurality of measurement axes, and in addition to the X and Y positions of wafer stage WST, rotation (yawing (θz rotation that is rotation around the Z axis)), pitching (X axis) Rotation around (θx rotation) and rolling (θy rotation around Y axis)) can also be measured.

  The position of the wafer W in the Z-axis direction with respect to the lens barrel 17 of the projection optical system PO is measured by a grazing incidence type wafer focus sensor. As shown in FIG. 1, the wafer focus sensor is fixed to a column (not shown) that holds the barrel of the projection optical system PO, and a light transmission system 14a that irradiates a detection beam from an oblique direction to the upper surface of the wafer W. And a light receiving system 14b that is fixed to a column (not shown) and receives the detection beam reflected by the wafer W surface. As this wafer focus sensor (14a, 14b), a multipoint focal position detection system similar to the reticle focus sensor (13a, 13b) is used.

  The measurement values of the wafer interferometer 82W and the wafer focus sensors (14a, 14b) are supplied to the stage controller 70 in the main controller 20 of FIG. 4, and the stage controller 70 controls the wafer stage drive system 62. The position and orientation control of wafer stage WST in the six-dimensional direction is performed.

  At one end of the upper surface of wafer stage WST, measurement of the relative positional relationship between the position on the wafer surface onto which the pattern formed on reticle R is projected and an alignment system ALG described later (so-called baseline measurement) is performed. An aerial image measuring instrument FM is provided. This aerial image measuring instrument FM corresponds to a reference mark plate of a conventional DUV exposure apparatus.

  Furthermore, in this embodiment, as shown in FIG. 1, the alignment system ALG is fixed to the lens barrel of the projection optical system PO. The alignment system ALG employs an FIA (Field Image Alignment) system in which broadband light is irradiated onto an alignment mark (or aerial image measuring instrument FM) on the wafer W, the reflected light is received, and mark detection is performed by image processing. LIA (Laser Interferometric Alignment) that irradiates the diffraction grating-shaped alignment mark on the wafer W from two directions, interferes with the two generated diffracted lights, and detects the position information of the alignment mark from the phase. An alignment sensor of the LSA type (Laser Step Alignment) that irradiates the alignment mark on the wafer W to the alignment mark on the wafer W and measures the mark position using the intensity of the diffracted / scattered light, and an AFM (interatomic) Various types such as a scanning probe microscope such as a force microscope can be used. .

  In the present embodiment, reticle stage RST, projection optical system PO, wafer stage WST, and the like are actually housed in a vacuum chamber (not shown).

  As the wavefront sensor 90, a Shack-Hartmann wavefront sensor using a micromirror array in a light receiving optical system is used. As shown schematically in FIG. 2, the wavefront sensor 90 has a housing having an internal space in which the XZ cross section is substantially rectangular and the upper end (+ Z end) of the + X side protrudes. 97, a light receiving optical system including a plurality of optical elements arranged in a predetermined positional relationship inside the casing 97, and a detection arranged near the −X side and −Z side end portions inside the casing 97 Instrument 95.

  The casing 97 has a circular opening 97 a in a plan view at the uppermost part (+ Z side end face), and the opening 97 a is closed by a marking plate 91.

  The marking plate 91 is, for example, a glass substrate as a base material, and is disposed at the same height position (Z-axis direction position) as the surface of the wafer W placed on the wafer stage WST via a wafer holder (not shown). (See FIG. 1). A reflective film is formed on the surface of the marking plate 91 by vapor deposition of a metal such as chromium. A circular through hole 91a is formed at the center of the reflective film. In this case, the EUV light is blocked from entering the receiving optical system by unnecessary EUV light from the surroundings when the wavefront aberration of the projection optical system PO is measured by a portion other than the through hole 91a. EUV light passes only through the holes 91a). In addition, three or more sets of two-dimensional position detection marks whose positional relationship with the through hole 91a is known by design are formed around the through hole 91a of the reflective film. As the two-dimensional position detection mark, for example, a combination of a line and space mark formed along the Y-axis direction and a line and space mark formed along the X-axis direction can be employed. The line and space mark can be detected by the alignment system ALG.

  The light receiving optical system includes a condensing mirror 92 made of a concave mirror disposed below a sign plate 91 inside the casing 97, and a micro mirror array 94 disposed on the −X side of the condensing mirror 92. Has been. The condensing mirror 92 is fixed to the inside of the wall of the casing 97 via a holding member (not shown).

  The light incident on the condenser mirror 92 is converted into parallel light and then incident on the micromirror array 94.

  As shown in FIG. 3, the micromirror array 94 is formed of an elongated rectangular plate-shaped member inclined at 45 ° with respect to the X axis in the XZ plane, and one surface thereof (the surface on the back side of the paper in FIG. 3). 11A is shown in FIG. 11A, the first reflecting surface 94a in which a plurality of (10 in FIG. 11A) minute reflecting surface regions (reflecting surfaces) are formed in a line along the longitudinal direction. The other surface (the front surface in FIG. 3) is a planar second reflecting surface 94b that is mirror-finished. The first reflecting surface 94a is obtained by etching a parallel flat glass plate and depositing, for example, a multilayer film in which about 50 pairs of molybdenum Mo and beryllium Be films are alternately deposited with a period of about 5.5 nm. Created by forming a surface. In the micromirror array 94, an imaging light beam of a pinhole pattern image to be described later is emitted through the through hole 91a of the marking plate 91 for each reflection surface area.

  The micromirror array 94 is rotatably supported by support members 52 and 53 at the upper and lower end portions thereof. A rotation drive mechanism including a rotation motor and the like is provided in the support member 52 so that the micromirror array 94 is rotationally driven in the direction of arrow A shown in FIG. 3 by the rotation drive mechanism. It has become. In the following description, for convenience of description, the rotation drive mechanism is referred to as a “rotation drive mechanism 52” using a reference numeral of a support member provided therein.

  A magnetic pole unit 56A is provided on the surface of the rotation drive mechanism 52 opposite to the micromirror array 94, and a magnetic pole unit 56B is provided on the opposite side of the support member 53 from the micromirror array 94. The magnetic pole unit 56A and the armature unit 58A shown in FIG. 3 constitute a linear motor LM1, and the magnetic pole unit 56B and the armature unit 58B constitute a linear motor LM2. The armature units 58 </ b> A and 58 </ b> B are in a state where their + Y side end and −Y side end are fixed to the inner wall of the casing 97. The micromirror array 94 is moved in the Y-axis direction by the linear motors LM1 and LM2.

  Although not shown in FIG. 3, a position detection device 41 (see FIG. 4) for measuring the position of the micromirror array 94 in the Y-axis direction is provided in part of the micromirror array 94 and the linear motor. It has been. As the position detection device 41, for example, a linear encoder can be adopted. This position detection device 41 is connected to the timing control unit 40 in the main control device 20 of FIG. 4, and outputs the Y position information of the micromirror array 94 to the timing control unit 40. The timing control unit 40 The movement of the micromirror array 94 is controlled based on the Y position information.

  Returning to FIG. 2, the detector 95 includes a light receiving element (hereinafter referred to as an “area sensor”) including a two-dimensional area sensor, and an electric circuit such as a charge transfer control circuit. The area sensor has an area sufficient to receive all the light beams emitted from the micromirror array 94. In the area sensor, when the first reflecting surface 94a of the micromirror array 94 is disposed on the optical path, an image of a pinhole pattern (described later) formed in the vicinity of the through hole 91a is the first of the micromirror array 94. The image forming surface is re-imaged by each reflecting surface region on the reflecting surface 94a, and has a light receiving surface on the optical conjugate surface of the through hole 91a forming surface. In addition, this light receiving surface is located on a surface slightly deviated from the conjugate surface of the pupil plane of the projection optical system PO when the second reflecting surface 94b of the micromirror array 94 is disposed on the optical path.

  In the detector 95, the imaging result of the pinhole pattern image re-imaged by each reflecting surface area in a state where the first reflecting surface 94a of the micromirror array 94 is arranged on the optical path is used as imaging data IMD1. It transmits to the A / D converter 42 of FIG. In the detector 95, when the second reflecting surface 94b of the micromirror array 94 is disposed on the optical path, the A / D converter 42 uses the imaging result of the image formed on the light receiving surface as the imaging data IMD2. Send to.

  As shown in FIGS. 2 and 3, the detector 95 is connected at its −X side end to the lower end of a connecting member 98 whose longitudinal direction is the Z-axis direction, and the upper end of the connecting member 98. The part is connected to the support member 53. For this reason, as the micromirror array 94 moves in the Y-axis direction, the detector 95 also moves by the same amount in the Y-axis direction. A guide member for guiding the detector 95 and the micromirror array 94 in the Y-axis direction may be provided.

  Although the outer shape of the casing 97 is not shown in FIG. 2, it has a shape that fits with the sensor mounting portion of the wafer stage WST described above and is detachable from the wafer stage WST.

  FIG. 4 schematically shows the main part of the control system of the present embodiment. The control system of FIG. 4 is configured with the main controller 20 as the center. The main controller 20 includes a stage controller 70 and a timing controller 40. The timing controller 40 controls the driving of the linear motors LM1 and LM2 based on the position information from the position detector 41 described above. The light emission by the illumination system 11 is also controlled. The timing control of the detector 95, the A / D converter 42 that performs A / D conversion on the imaging result of the detector 95, the two-dimensional image memory 43, and the calculation unit 44 in the main controller 20 is also performed. The main controller 20 controls each part of the exposure apparatus 10.

  Next, the measurement operation of the optical characteristics in the exposure apparatus 100 of the present embodiment will be described along the flowcharts of FIGS. 5 to 9 showing the processing algorithm of the main controller 20 with reference to other drawings as appropriate. Further, as a premise of the following operation, it is assumed that wavefront sensor 90 is mounted on wafer stage WST, and that wavefront sensor 90 and main controller 20 are connected.

  It is assumed that the aberration of the light receiving optical system inside the wavefront sensor 90 is at a negligible level.

  First, the subroutine of the wavefront aberration measurement subroutine of the projection optical system PO in step 102 in FIG. 5 is performed.

  In this subroutine 102, first, in step 122 of FIG. 6, a reflective measurement reticle RT (see FIG. 10A) is loaded onto the reticle stage RST using a reticle loader (not shown).

  The measurement reticle RT has a plurality of (for example, 3 × 11 = 33) pinhole-shaped reflection patterns (hereinafter referred to as “pinhole patterns”) loaded on the reticle stage RST in the X-axis direction. And a Y-axis direction is formed in a matrix arrangement with the row direction and the column direction, respectively. It is assumed that the pinhole pattern is formed in a region having the size of an arc slit-shaped illumination region.

  In the next step 124, setting is made so that the first reflecting surface 94a of the micromirror array 94 is arranged on the optical path (optical axis) (state of FIG. 10A). Here, the rotation drive mechanism 52 connected to the micromirror array 94 is driven and controlled, and the linear motors LM1 and LM2 are driven and controlled. If the first reflecting surface 94a is already placed in the optical path, it is maintained as it is.

  In the next step 125, the positional relationship between wavefront sensor 90 mounted on wafer stage WST and wafer stage WST is measured. Specifically, the wafer stage WST is sequentially moved, and the position of at least two two-dimensional position marks on the sign plate 91 of the wavefront sensor 90 on the wafer stage coordinate system is detected using the alignment system ALG. Based on the position detection result, the positional relationship between the through hole 91a of the marking plate 91 of the wavefront sensor 90 and the wafer stage WST is accurately obtained by a predetermined statistical calculation such as a least square method.

  As a result, the XY position of the through hole 91a can be accurately detected based on the position information (velocity information) output from the wafer interferometer 82W, and the detection result of the XY position and the alignment system measured in advance. By controlling the movement of wafer stage WST via wafer stage drive system 62 based on the ALG baseline, through hole 91a can be accurately positioned at a desired XY position.

  In the next step 126, the inclination of the marking plate 91 with respect to a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PO is measured using the wafer focus sensors (14a, 14b).

  In the next step 128, the inclination of wafer stage WST is adjusted via wafer stage drive system 62 on the basis of the measurement result of the inclination described above, whereby the inclination of the upper surface of marking plate 91 is changed to the image plane of projection optical system PO ( Or the inclination of the approximate plane of the image plane).

  In the next step 130, a reference measurement point in the field of view of the projection optical system PO, for example, a measurement point at the center of the field of view, that is, a pinhole pattern located at the center of 33 (hereinafter referred to as “center pinhole pattern”) The wafer stage WST is moved so that the through hole 91a of the marking plate 91 of the wavefront sensor 90 coincides with the measurement point of the conjugate position (on the optical axis AX) of the projection optical system PO.

  In the next step 132, imaging data IMD1 which is an imaging result of the image of the central pinhole pattern re-imaged on the light receiving surface of the measuring instrument 95 by each reflecting surface area of the first reflecting surface 94a of the micromirror array 94. Based on the above, the optimum Z position (best focus position) of wafer stage WST is searched. Specifically, it is as follows.

  The optical arrangement at the time of searching for the optimum Z position is shown in FIG. In such an optical arrangement, when the timing controller 40 of the main controller 20 oscillates the laser light from the light source device 12 and the illumination light EL is emitted from the illumination optical system, it reaches the pinhole pattern at the center of the measurement reticle RT. The reflected light (illumination light EL) is reflected by the central pinhole pattern. Then, the light passes through the projection optical system PO, and is then collected in the through hole 91a of the marking plate 91 of the wavefront sensor 90. The light reflected by the pinhole pattern other than the central pinhole pattern does not reach the through hole 91a. The wavefront of the light condensed in the through hole 91a in this manner (the image light beam of the central pinhole pattern imaged inside the through hole 91a on the surface of the marking plate 91) is substantially including the wavefront aberration of the projection optical system PO. It becomes a spherical surface.

  The light that has passed through the through-hole 91 a is converted into parallel light by the condensing mirror 92 and then enters the first reflecting surface 94 a of the micromirror array 94. The first reflecting surface of the micromirror array 94 is an optical conjugate of the central pinhole pattern imaged inside the through hole 91a on the surface of the indicating plate 91 for each reflecting surface region. An image is formed on the surface, that is, the imaging surface (light receiving surface) of the detector 95. Accordingly, an arrangement and a number of spot images (an image of a pinhole pattern in the center) corresponding to the reflection surface area of the micromirror array 94 are formed on the imaging surface of the detector 95. The detector 95 captures spot images formed on the imaging surfaces (light receiving surfaces). Imaging data IMD1 obtained by imaging by the detector 95a is transmitted to the A / D converter 42 in FIG.

  Therefore, while moving the wafer stage WST stepwise in the Z-axis direction via the wafer stage drive system 62, the imaging data IMD1 (however, the imaging data IMD1 in this case means light quantity (luminance) instead of position information). Based on the captured image data IMD1, the optimum Z position of wafer stage WST is searched by finding the position in the Z-axis direction where the contrast is maximum, for example.

  In the next step 134, an optimum exposure amount at the time of wavefront aberration measurement is determined. Specifically, the image data IMD1 is captured while changing the oscillation frequency (repetition frequency) of the light source device 12, for example, with the position of the wafer stage WST in the Z-axis direction adjusted to the optimal Z position. The optimum exposure amount is determined by repeatedly obtaining the repetition frequency corresponding to the imaging data IMD1 that optimizes the number of pulses with respect to the charge accumulation time in the detector 95 based on the captured imaging data IMD1.

  In the next step 136, the micromirror array 94 is rotated in the direction of arrow A via the rotation driving device 52, and the second reflecting surface 94b is disposed on the optical path (optical axis) (state shown in FIG. 10B).

  In the next step 138, an optimum exposure amount at the time of pupil image measurement described later is determined. Specifically, it is as follows.

  FIG. 10B shows an optical arrangement when determining the optimum exposure amount at the time of pupil image measurement. In such an optical arrangement, when laser light is oscillated from the light source device 12, light (illumination light EL) that has reached the central pinhole pattern of the measurement reticle RT is reflected by the central pinhole pattern, as described above. Then, after passing through the projection optical system PO, the light that is collected in the through hole 91a of the sign plate 91 of the wavefront sensor 90 and passes through the through hole 91a is converted into parallel light by the condenser mirror 92, and then the micromirror. The light is received by the detector 95 via the second reflecting surface 94 b of the array 94. Thereby, a part of the light source image on the pupil plane of the projection optical system PO is projected onto the light receiving surface of the detector 95. The detector 95 captures an image projected on the imaging surface (light receiving surface), and the imaging data IMD2 obtained by the imaging is transmitted to the A / D converter 42.

  Therefore, for example, while taking in the imaging data IMD2 is repeated while changing the oscillation frequency (repetition frequency) of the light source device 12, the number of pulses with respect to the charge accumulation time in the detector 95 is determined based on the taken imaging data IMD2. By obtaining a repetition frequency corresponding to the optimum imaging data IMD2, an optimum exposure amount at the time of pupil image measurement described later is determined.

  Here, the pupil image refers to a light source image formed on the pupil plane of the projection optical system PO by light incident on the projection optical system PO via a pinhole pattern described later. It is affected by the deviation of the optical axis of the incident light. Therefore, the measurement of the pupil image is a kind of measurement of the optical characteristics of the projection optical system PO. Of course, the wavefront aberration is a kind of optical characteristic of the projection optical system PO.

  In the next step 142 (FIG. 7), the counter n indicating the number of the measurement point is initialized to 1 (n ← 1), and the process proceeds to step 146. In step 146, the wavefront sensor 90 is moved to the nth (here, the first) measurement point. That is, wafer stage WST is moved so that through hole 91a of sign plate 91 of wavefront sensor 90 coincides with the measurement point at the conjugate position with respect to projection optical system PO of the nth pinhole pattern.

  In the next step 148, pupil image measurement is performed under the optimum exposure amount previously determined in step 138. Specifically, first, in step 202 of FIG. 8, a counter m indicating the position of the micromirror array 94 (second reflecting surface 94b) is initialized to 1 (m ← 1).

  Next, in step 204, the positions of the micromirror array 94 (second reflecting surface 94b) and the detector 95 are positioned at the m-th (here, the first) position. Here, the micromirror array 94 is movable by the linear motors LM1 and LM2 from the first position to the Mth position in the Y-axis direction, and the first position is within the movable range of the micromirror array 94. It is assumed that the position is the position of the −Y side end (see FIG. 11A).

  In the next step 206, light emission of the light source device 12 is started, and charge accumulation by the detector 95 is started.

  In the next step 208, the process waits until a predetermined time (here, for example, a minute time necessary for charge accumulation) elapses. When the predetermined time elapses, the light emission of the light source device 12 is terminated in step 210, and the detector 95 performs. The charge accumulation is terminated.

  In the next step 212, the signal from the detector 95 is read out and converted into a digital signal using the A / D converter 42. In step 214, the converted digital signal is converted to the mth (here, the first) in the image memory 43. ) Is stored in the area corresponding to.

  In the next step 216, it is determined whether m = M. If the determination here is negative, in step 218, m is incremented by 1 (m ← m + 1), and then the process returns to step 204.

  Thereafter, in step 204, the positions of the micromirror array 94 (second reflection surface 94b) and the detector 95 are positioned at the m-th (here, second) position, and the processing from step 206 to step 214 is performed. Here, it is assumed that the mth position and the (m + 1) th position of the micromirror array 94 are separated by the same distance as the width of the micromirror array 94 in the Y-axis direction.

  In this way, the processing and determination in steps 204 to 218 are repeated, and when the detection from the first to the Mth position is completed, the detection over the entire pupil image is completed, so the determination in step 216 is affirmed, Control goes to step 220.

  In step 220, the signal stored in the image memory is processed to obtain a pupil image, and the process proceeds to step 150 in FIG.

  In step 150, it is determined whether the value of the counter n is equal to or greater than the total number N of measurement points (N = 33 in this case), thereby determining whether pupil image measurement has been completed at all measurement points. . Here, since the pupil image measurement has only been completed for the first measurement point, the determination here is denied, and the routine proceeds to step 152 where the counter n is incremented by 1, and then the procedure returns to step 146.

  Thereafter, the loop processing of steps 146 → 148 → 150 → 152 is repeated until the determination in step 150 is affirmed. As a result, pupil image measurement is performed on measurement points at conjugate positions with respect to the projection optical system PO of the 2nd to 33rd measurement points in the field of view of the projection optical system PO, and light source image data (all through the pinhole pattern) ( The position information of the light source image such as the center position and size) is extracted.

  When pupil image measurement is completed for all measurement points, the process proceeds to step 154 to initialize the counter n to 1.

  In the next step 156, after the first reflecting surface 94a of the micromirror unit 94 is again placed on the optical path, in step 158, the wavefront sensor 90 is moved to the nth (here, the first) measurement point. That is, wafer stage WST is moved so that through hole 91a of sign plate 91 of wavefront sensor 90 coincides with the measurement point at the conjugate position with respect to projection optical system PO of the nth pinhole pattern.

  In the next step 160, steps 302 to 318 in FIG. 9 are performed in the same manner as steps 202 to 218 in FIG. 8 described above until the determination in step 316 is affirmed, and the digital signal is stored in the image memory. deep. However, Steps 302 to 318 are different from Steps 202 to 218 in that the first reflecting surface 94a of the micromirror array 94 is disposed on the optical path.

  In this case, as shown in FIG. 11A, the wavefront shift is measured while moving from the first position to the Mth position. Here, at each position, as shown in FIG. 11B, when the wavefront is ideal, a spot image is formed at a position indicated by a white circle on the imaging surface of the detector 95, and the wavefront is shifted. In the case of a spot image, a spot image is formed at a position deviated from a white circle as indicated by a black circle according to the deviation (inclination).

  Therefore, as shown in FIG. 11C, the shift of the spot image in the two-dimensional plane can be detected while moving from the first position to the Mth position and measuring. ing.

  Specifically, the detection of the position of the spot image is performed by calculating the center position of each spot image by calculating the center of gravity of the light intensity distribution of each spot image and calculating the center position of each spot image as the imaging data IMD1. Is stored in the image memory 43.

  In step 320, the position information of each spot image is read from the image memory 43, and the wavefront aberration of the projection optical system PO related to the light via the nth (here, the first) pinhole pattern on the measurement reticle RT is determined. The calculation is performed as described later.

  By the way, the reason why the wavefront aberration can be measured from the position information of the spot image is that the wavefront of the light incident on the micromirror array 94 reflects the wavefront aberration of the projection optical system PO when the spot image is captured. Because.

  That is, when there is no wavefront aberration in the projection optical system PO, the wavefront WF is a plane orthogonal to the optical axis as shown by the dotted line in FIG. When there is an aberration, as indicated by a two-dot chain line in FIG. 10A, the wavefront WF ′ is not a plane but a plane having an inclination of an angle corresponding to the position on the plane. In this case, the wavefront of the light incident on each reflecting surface area of the first reflecting surface 94a of the micromirror array 94 is tilted, and the point shifted from the case where there is no wavefront aberration by a distance corresponding to the tilt amount is the center. The spot image to be formed is formed on the imaging surface of the detector 95.

  Accordingly, in this step 320, each spot image position expected when there is no wavefront aberration (a position indicated by a white circle in FIGS. 11B and 11C) and each detected spot image position (FIG. B), the position of the Zernike polynomial that expands the wavefront is obtained from the difference (position error indicated by the black circle in FIG. 11C) via the nth pinhole pattern in the measurement reticle RT. The wavefront aberration of the projection optical system PO related to light is calculated.

  Returning to the description of FIG. 7, in the next step 166, it is determined whether or not the value of the counter n is equal to or greater than the total number N of measurement points (N = 33 in this case). It is determined whether or not the measurement is finished. Here, since the measurement of the wavefront aberration has only been completed for the first measurement point, the determination here is denied, the process proceeds to step 168, the counter n is incremented by 1, and then the process returns to step 158.

  Thereafter, the processing of the loop of steps 158 → 160 → 162 → 164 → 166 → 168 is repeated until the determination in step 166 is affirmed. As a result, wavefront aberration measurement is performed on the measurement points at the conjugate positions of the projection optical system PO with respect to the projection optical system PO of the second to 33rd pinhole patterns in the field of view of the projection optical system PO. Wavefront aberrations relating to light through each pattern are calculated and stored in memory.

  When the wavefront aberration measurement is completed for all measurement points and the determination in step 166 is affirmative, the process returns to step 104 of the main routine of FIG.

  In this step 104, the wavefront aberration of the projection optical system PO is measured at all measurement points based on the wavefront aberration data at N (here, 33) measurement points in the field of view of the projection optical system PO obtained above. It is determined whether or not it is less than the allowable value. If this determination is negative, the process proceeds to step 106, and the projection optical system PO is set so as to reduce the currently generated wavefront aberration based on the measurement result of the wavefront aberration of the projection optical system PO. The wavefront aberration of the projection optical system PO is adjusted by driving at least a part of the six mirrors.

  Thereafter, the subroutine of step 102 is performed, and the wavefront aberration related to the adjusted projection optical system PO is measured in the same manner as described above. Thereafter, the adjustment of the wavefront aberration of the projection optical system PO (step 106) and the measurement of the wavefront aberration (step 102) are repeatedly executed until a positive determination is made in step 104. If a positive determination is made in step 104, the process proceeds to step 108.

  In step 108, an alarm sound is generated via an input / output device (not shown) and “wavefront aberration measurement end” is displayed on the display screen to notify the operator that the wavefront aberration has been measured.

  Thereafter, it waits for the wavefront sensor 90 to be removed from the wafer stage WST, and in step 110, confirming that the wavefront sensor 90 has been removed from the wafer stage WST by, for example, an output of a sensor (not shown) or a notification from an operator. A series of operations for measuring optical characteristics according to this embodiment is completed.

  Thereafter, the exposure operation is performed, and the measurement reticle RT loaded on the reticle stage RST is unloaded via a reticle loader (not shown), and the reticle R on which the pattern to be transferred is formed is placed on the reticle stage RST. Load and perform preparatory operations such as baseline measurement using alignment system ALG.

  Then, the wafer on the wafer stage WST is exchanged via a wafer loader (not shown) (however, if the wafer is not loaded on the wafer stage WST), the wafer W is aligned (for example, EGA method). And the wafer stage WST is moved to the scanning start position (acceleration start position) for exposure of each shot area on the wafer W based on the alignment result, the reticle stage RST, Step-and-scan that repeats the operation of illuminating the reticle R with illumination light EL and transferring the pattern of the reticle R to the shot area on the wafer W while performing relative scanning in the Y-axis direction in synchronization with the wafer stage WST. System exposure is performed.

  During the above-described scanning exposure and alignment, the wafer focus sensor (14a, 14b) measures the position of the surface of the wafer W relative to the image plane of the projection optical system PO and the tilt with respect to the image plane, and the main controller shown in FIG. Wafer stage WST is controlled by stage controller 70 within 20 so that the position of wafer W surface relative to the image plane of projection optical system PO and the inclination relative to the image plane are always constant. In the control device, the position of the pattern surface of the reticle R relative to the object surface of the projection optical system PO during exposure (during the transfer of the reticle pattern) based on the measurement value of the reticle focus sensor (13a, 13b) and the object surface The reticle stage RST and wafer stage WST are moved synchronously along the Y-axis direction while adjusting the position of the projection optical system PO of the reticle R in the optical axis direction (Z direction) so that the tilt is always kept constant. Let

  As described above in detail, according to the wavefront sensor 90 of the present embodiment, the wavefront sensor 90 is formed of an elongated rectangular plate-like member that is inclined by 45 ° with respect to the X axis in the XZ plane, and is arranged in one axial direction (longitudinal direction). The micromirror array 94 having a plurality of reflecting surface areas is moved in the Y-axis direction orthogonal to the uniaxial direction within the plane by the linear motors LM1 and LM2, and the detector 95 includes the projection optical system PO and the micromirror array. Light is received through 94, and a detection signal including information on the optical characteristics of the projection optical system PO is output. For this reason, it is possible to measure wavefront aberration even in an exposure apparatus that uses light of a wavelength that does not transmit through the glass. In addition, since it is not necessary to arrange the reflective surface area of the micromirror array 94 in a two-dimensional plane, it is possible to manufacture a highly accurate micromirror array at low cost and realize highly accurate optical characteristic measurement. is there.

  Further, according to the exposure apparatus 10 of the present embodiment, the wavefront sensor 90 of the present embodiment is provided on the wafer stage WST so that the projection optical system PO is the optical system to be tested. The characteristic can be measured with high accuracy, and the pattern formed on the reticle R can be transferred onto the wafer W with high accuracy by adjusting the projection optical system based on the measurement result.

  Further, in the present embodiment, the above-described pupil image (light source image) data (light source image) based on the detection signal from the detector 95 in a state where the second reflecting surface 94b of the microlens array 94 is disposed on the optical path. The position information of the light source image such as the center position and size) is calculated. This is because it is desirable to correct the deviation of the reference position for obtaining the wavefront aberration based on the pupil position and size of the projection optical system PO in order to accurately obtain the wavefront aberration using the Zernike polynomial. is there. That is, as described above, the position of the light source image is accurately detected using the light source image picked up by the detector 95 as a detection target, and the reference position is determined based on the position and size of the detected light source image. Since the deviation is corrected, in this embodiment, the wavefront aberration can be accurately measured.

  In this embodiment, since the micromirror array 94 and the detector 95 are integrally coupled using the connecting member 98, the drive for driving the detector 95 in synchronization with the micromirror array 94 is performed. There is no need to provide a separate mechanism. In the present embodiment, the detector 95 is also miniaturized in accordance with the micromirror array, so the amount of heat generation is small, and high-precision optical characteristics can be measured from this point.

  In the above embodiment, the micromirror array 94 is configured to include a first reflecting surface 94a provided with a plurality of minute reflecting surface areas and a second reflecting surface 94b having a planar reflecting surface. Although the case where the rotation drive mechanism 52 is employed as the switching device for inserting and removing the planar reflecting surface on the optical path has been described, the present invention is not limited to this. For example, as shown in FIG. 12A, in addition to the micromirror array 94 provided with only the first reflective surface 94a, a planar mirror 194 provided with a planar reflective surface is prepared, and pupil image measurement is performed. In some cases, as shown in FIG. 12A, the micromirror array 94 is retracted out of the optical path and the plane mirror 194 is disposed on the optical path of the illumination light EL. As shown in FIG. 4, the plane mirror 194 may be retracted out of the optical path and the micromirror array 94 may be disposed on the optical path of the illumination light EL. In this case, as shown in FIGS. 12A and 12B, the stators of the linear motors LM1 ′ and LM2 ′ that drive the micromirror array 94 and the plane mirror 194 can be made common. Moreover, not only the structure of FIG. 12 (A) and FIG. 12 (B) but various structures can be employ | adopted if it is a structure which can arrange | position a micromirror array and a plane mirror on an optical path.

  In the above embodiment, the micromirror array 94 and the detector 95 are integrally coupled using the connecting member 98 to move the micromirror array 94 and the detector 95 synchronously. Not only the connecting member 98 but also the micro mirror array 94 and the detector 95 may be moved by a moving mechanism such as another linear motor.

  In the above embodiment, an area sensor that matches the size of the micromirror array 94 is used as the detector 95. However, the present invention is not limited to this, and the area sensor may be an illumination light source. An area sensor having a size that can receive all light can also be employed. Further, not only the area sensor but also a line sensor can be adopted so that all of the illumination light can be measured while shifting by one pixel.

  Further, a so-called TDI (Time Delay Integration) sensor may be employed as the detector. This TDI sensor is a kind of line sensor, but has a two-dimensional structure in which pixels are arranged not only in one axis direction but also in another axis direction perpendicular to the one axis direction. This TDI sensor moves in the direction of the other axis and integrates information from the pixels in the direction of the other axis to form one image. Therefore, the TDI sensor performs measurement with higher speed and higher sensitivity than a normal CCD line sensor. be able to.

  In the above-described embodiment, the movement is performed at the same pitch as the size of the reflection surface area. However, the movement is not limited to this, and the movement may be performed at a pitch larger than the size of the reflection surface area and sequentially positioned. .

  In the above embodiment, the linear encoder is used as the position detection device for measuring the position of the micromirror array 94 in the Y-axis direction. However, the present invention is not limited to this, and other detection devices such as a laser interferometer are used. It's also good.

  In the above-described embodiment, the case where at least the linear motors LM1 and LM2 are included as moving devices that move the micromirror array 94 in the Y-axis direction has been described. However, the present invention is not limited to this, and for example, rotation Various moving devices such as a ball screw type moving device using a motor can be used.

  In the above-described embodiment, the micromirror array 94 is formed as a single body, and one surface is a first reflecting surface 94a in which a number of reflecting surface regions are formed, and the other surface is a planar second reflecting surface 94b. However, the present invention is not limited to this. The first reflecting member on which the first reflecting surface 94a is formed and the second reflecting member on which the second reflecting surface 94b is formed. It is good also as sticking a sheet to make one micromirror array.

  In the above embodiment, the case where the reflective surface regions are arranged in a line in the longitudinal direction on the first reflective surface 94a of the micromirror array 94 has been described, but the present invention is not limited to this, for example, As long as the micromirror array 94 can be manufactured relatively easily, the number of columns may be arbitrarily set to two columns, three columns, or the like. Alternatively, the micromirror array 94 may be only one minute reflecting surface area, and the optical characteristics may be measured in the two-dimensional plane by moving the one reflecting surface area in the two-dimensional plane. In these cases, the size of the detector 95 may be matched to the size of the micromirror array.

  In the above embodiment, wavefront aberration measurement is performed at 33 measurement points after all pupil images at 33 measurement points are measured. However, the present invention is not limited to this, and each measurement is performed. It is also possible to alternately perform pupil image measurement and wavefront aberration measurement at a point. For example, the former may be the first mode, the latter may be the second mode, and the operator may select which mode to perform the measurement.

  In the above embodiment, the number of pinhole patterns in the measurement reticle RT is 11 × 3 = 33. However, the number can be increased or decreased according to the measurement accuracy of the desired wavefront aberration.

  In the above embodiment, the measurement reticle RT is loaded onto the reticle stage RST when measuring the wavefront aberration of the projection optical system PO. However, a pattern plate on which a pinhole pattern similar to the measurement reticle is formed is used. The wavefront aberration of the projection optical system PO may be measured by placing the pattern plate on the reticle stage RST and aligning the pattern plate with the field of view of the projection optical system PO.

  Further, in the above embodiment, the aberration of the light receiving optical system inside the wavefront sensor 90 is negligibly small. However, in the case of performing wavefront aberration measurement with higher accuracy, the time until the wavefront aberration is calculated. At that time, the wavefront aberration of the light receiving optical system alone may be measured. The measurement of the wavefront aberration of the light receiving optical system alone is performed by using a pattern plate on which a pinhole opening having a size that generates a spherical wave by irradiation of the illumination light EL through the projection optical system PO is formed on the display plate 91. A wavefront aberration measurement similar to that described above is performed by irradiating the pattern plate with the illumination light EL emitted from the projection optical system PO in a state where the through hole 91a is further limited by the pinhole opening of the pattern plate. It can be realized by doing. Then, when calculating the wavefront aberration of the projection optical system PO, the wavefront aberration of the light receiving optical system alone may be used as a correction value.

  Similarly, in order to obtain the wavefront aberration accurately, the dark current of the detector 95 is measured at any point in time until the wavefront aberration is calculated, and the value (luminance value) of each pixel is obtained. In addition, the offset due to the dark current may be corrected. Such offset correction may be performed in the case of the above-described pupil image measurement or the like.

  In the above embodiment, the case where the wavefront aberration measurement and the wavefront aberration adjustment of the projection optical system PO are performed at the time of periodic maintenance after the exposure apparatus is assembled and the like is prepared for the subsequent wafer exposure is described. When adjusting the projection optical system PO in the manufacture of the apparatus, the wavefront aberration may be adjusted in the same manner as in the above embodiment. When adjusting the projection optical system PO at the time of manufacturing the exposure apparatus, in addition to the position adjustment of some mirrors constituting the projection optical system PO performed in the above embodiment, the position adjustment of other mirrors and mirrors It is possible to rework, replace the mirror, etc.

  In the above embodiment, the case where the wavefront sensor 90 is detachable from the wafer stage WST has been described. However, the present invention is not limited to this, and the wavefront sensor 90 may be permanently installed in the wafer stage WST. Further, it may be permanently installed on a stage different from the wafer stage.

  In the above embodiment, the case where the projection optical system is employed as the test optical system has been described. However, the present invention is not limited to this, and an illumination optical system may be employed as the test optical system. .

In the above embodiment, the case where the EUV light is used as the exposure light and the all-reflection projection optical system including only six mirrors is used is described as an example, and the present invention is not limited thereto. Of course. That is, for example, an exposure apparatus having a projection optical system composed of only four mirrors as disclosed in Japanese Patent Application Laid-Open No. 11-345761, as well as a VUV light source having a wavelength of 100 to 160 nm, such as an Ar ₂ laser ( The present invention can be suitably applied to a projection optical system having a wavelength of 126 nm) and having 4 to 8 mirrors. Further, the present invention can be suitably applied to both a refractive projection optical system including only a lens and a catadioptric projection optical system including a lens in part.

In the above embodiment, the case where the wavefront sensor 90 is provided in the EUV exposure apparatus has been described. However, the present invention is not limited to this, and an ultraviolet pulse light source such as an F ₂ laser light source, an ArF excimer laser light source, or a KrF excimer laser light source, g It is also possible to provide the wavefront sensor 90 of the above-described embodiment in an exposure apparatus that uses an ultra-high pressure mercury lamp that emits bright lines such as a line (wavelength 436 nm) and an i line (wavelength 365 nm). In addition, a single wavelength laser beam oscillated from a DFB semiconductor laser or fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and a nonlinear optical crystal is obtained. It is also possible to use harmonics that have been converted into ultraviolet light.

  In the above embodiment, the case where the projection optical system constituting the exposure apparatus is adopted as the test optical system of the wavefront sensor 90 has been described. However, the present invention is not limited to this, and for example, the test optical system An illumination optical system may be employed as the system.

  In the above embodiment, the case where EUV light having a wavelength of 11 nm is used as exposure light has been described. However, the present invention is not limited to this, and EUV light having a wavelength of 13 nm may be used as exposure light. In this case, in order to secure a reflectance of about 70% with respect to EUV light having a wavelength of 13 nm, it is necessary to use a multilayer film in which molybdenum Mo and silicon Si are alternately laminated as the reflection film of each mirror.

  In the above embodiment, the laser excitation plasma light source is used as the exposure light source. However, the present invention is not limited to this, and any of SOR, betatron light source, discharged light source, X-ray laser, and the like may be used.

  In the above embodiment, the case of a scanning exposure apparatus has been described. However, the present invention is not limited to a step-and-repeat machine, a step-and-scan machine, a step-and-scan machine, and the like, as long as the exposure apparatus includes a projection optical system.・ It can be applied to any stitching machine.

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, but for example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern onto a square glass plate, an organic EL, a thin film magnetic head, a micromachine, etc. In addition, it can be widely applied to an exposure apparatus for manufacturing a DNA chip or the like. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern.

  Note that the present invention may be applied to an immersion exposure apparatus in which a liquid is filled between the projection optical system PO and the wafer, which is disclosed in, for example, International Publication WO99 / 49504.

  As described above, the optical property measuring apparatus of the present invention is suitable for measuring the optical property of the optical system to be detected. The exposure apparatus of the present invention is suitable for transferring a pattern formed on a mask onto a substrate.

It is a figure which shows schematic structure of the exposure apparatus which concerns on one Embodiment of this invention. It is a figure which shows the internal structure of the wavefront sensor of FIG. It is a perspective view which shows a micromirror array and a detector vicinity. FIG. 2 is a block diagram showing a main part of a control system of the exposure apparatus in FIG. 1. 2 is a flowchart showing a simplified processing algorithm of a main control device when measuring optical characteristics in the exposure apparatus of FIG. 1. It is a flowchart (the 1) which shows the process of step 102 of FIG. 6 is a flowchart (No. 2) showing a process of step 102 in FIG. It is a flowchart which shows the process of step 148 of FIG. It is a flowchart which shows the process of step 160 of FIG. FIG. 10A is a diagram showing the position of the optics at the time of capturing a spot image in one embodiment of the present invention, and FIG. Is a diagram showing a position. FIG. 11A to FIG. 11C are diagrams for explaining wavefront aberration measurement according to an embodiment. 12A and 12B are diagrams showing a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus, 41 ... Position detection apparatus (measurement apparatus), 52 ... Rotation drive mechanism (switching apparatus), 90 ... Wavefront sensor (optical characteristic measurement apparatus), 94 ... Micromirror array (wavefront division | segmentation optical element), 94a ... Second reflecting surface (plane mirror), 95 ... detector, 98 ... connecting member (coupling mechanism), LM1, LM2 ... linear motor (moving mechanism), PO ... projection optical system (test optical system), R ... reticle ( Mask), W ... wafer (object), WST ... wafer stage (object stage).

Claims (10)

An optical property measuring device for measuring optical properties of a test optical system,
A wavefront splitting optical element having a plurality of reflecting surface regions arranged in a uniaxial direction within a predetermined plane;
A moving mechanism for moving the wavefront splitting optical element in the other axis direction orthogonal to the one axis direction within the predetermined plane;
And a detector that receives light through the test optical system and the wavefront splitting optical element and outputs a detection signal including information on optical characteristics of the test optical system. A plane mirror capable of inserting and removing light on the optical path through the test optical system;
The optical characteristic measurement device according to claim 1, further comprising: a switching device that switches between a state in which the wavefront splitting optical element is disposed on an optical path of the light and a state in which the planar mirror is disposed.   The optical property measuring apparatus according to claim 1, wherein the detector is an area sensor. The drive mechanism moves the wavefront dividing optical element at a predetermined pitch that is equal to or larger than the size of the reflection surface region with respect to the other axis direction, and sequentially positions the optical element.
The optical detector according to claim 1, wherein the detector outputs the detection signal for each positioning.   The optical characteristic measuring device according to claim 1, further comprising a measuring device that measures a position of the wavefront splitting optical element in the other axis direction.   The optical property measuring apparatus according to claim 3, wherein the detector is movable in synchronization with the movement of the wavefront splitting optical element.   The optical characteristic measurement apparatus according to claim 6, further comprising a coupling mechanism that integrally couples the wavefront splitting optical element and the detector.   The optical property measuring apparatus according to claim 1, wherein the detector is a TDI sensor. An exposure apparatus for transferring a pattern formed on a mask onto an object,
An illumination optical system for illuminating the mask with illumination light;
A projection optical system that projects the illumination light emitted from the mask onto the object;
An object stage that holds the object and moves two-dimensionally;
The optical characteristic measurement apparatus according to claim 1, wherein the optical stage is provided on the object stage so that at least one of the illumination optical system and the projection optical system is the optical system to be detected. Exposure device. A reflective mask is used as the mask,
The exposure apparatus according to claim 9, wherein the illumination light is extreme ultraviolet light.

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