JP2005175177A - Optical apparatus and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly precisely and stably measure the position of a mirror stored in a mirror cylinder. <P>SOLUTION: In a laser interferometer to be used by the position measurement of a mirror M1 stored in a partial mirror cylinder 152c, an interferometer block 64x<SB>1</SB>including at least a beam splitter 72 for deciding the optical path length of an optical path independent of a light measurement beam among the optical paths of a reference beam and a reference mirror 74 is fixed to the partial mirror cylinder. That is, the rigidness of the partial mirror cylinder itself is made high so that a distance from the beam splitter to a reference mirror can be constantly maintained. Thus, the position of the mirror to be measured can be highly precisely and stably measured in a non-contact status based on a difference between the optical path length of the reference beam to be emitted to the reference mirror and the optical path length of the length measurement beam. Also, it is not necessary to use any largely scaled or heavy holding member as a holding member for holding the interferometer block, and it is possible to prevent the device from being largely scaled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical apparatus and an exposure apparatus, and more particularly to an optical apparatus suitable for use in a projection optical system and the like and an exposure apparatus including the optical 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, an ultraviolet ray from an ultra-high pressure mercury lamp, for example, i-line (wavelength 365 nm), KrF excimer laser light (wavelength 248 nm), or the like is used as illumination light (exposure beam) for exposure. It was. In recent years, in order to obtain a higher resolution (resolution), an exposure apparatus using an ArF excimer laser beam (wavelength 193 nm) as an exposure beam has been put into practical use. As a 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 finer semiconductor elements and the like, recently, an EUV exposure apparatus that uses soft X-ray region light having a wavelength of about 100 nm or less as exposure light, that is, EUV (Extreme Ultraviolet) light is used. Development 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.

  Regardless of whether a refraction system, a catadioptric system, or a reflection system is used as the projection optical system, in order to transfer the reticle pattern image onto the wafer with high resolution, the imaging characteristics of the projection optical system (various aberrations) ), And means for adjusting the position / attitude of at least some of the optical elements (hereinafter referred to as “movable optical elements”) constituting the projection optical system are generally used as means for this purpose. Adopted. In this case, it is necessary to measure the position of the movable optical element. However, as the resolution required for the projection optical system of the exposure apparatus increases year by year, more accurate position measurement is inevitably required. It has come to be.

  However, conventionally, a capacitance-type displacement sensor is mainly used for the position measurement of the movable optical element, so that the measurement accuracy is insufficient with respect to the required accuracy. Further, in the capacitance type displacement sensor, the measurement stroke may be insufficient with respect to the necessary adjustment stroke of the optical member.

  In particular, in the case of the aforementioned EUV exposure apparatus or the like, a plurality of mirrors are disposed inside the lens barrel of the projection optical system, and incident light beams and reflected light beams with respect to each mirror are inevitably concentrated in a space between these mirrors. Therefore, it may be difficult to dispose the displacement sensor in the space.

  As a means for improving the various disadvantages described above, it is conceivable to measure the position of an optical member such as the movable optical element using a laser interferometer that is actually employed in an experimental apparatus or the like. However, when the position of the optical member is measured using a laser interferometer in an actual projection optical system, for example, a huge structure holding the laser interferometer is installed around the projection optical system. It is necessary to employ a configuration in which the rigidity of the measurement system including the laser interferometer is higher than a certain level. This is because if the rigidity of the measurement system is low, the measurement accuracy decreases due to the influence of vibration and the like. However, it is difficult as a real problem to employ a projection optical system in which the above-described structure is installed as the projection optical system of the exposure apparatus, because it causes an unnecessarily large size and weight of the apparatus. It is. Also, depending on the exposure apparatus, it may be impossible to install a huge structure around the projection optical system due to space problems.

  The present invention has been made under the circumstances described above, and a first object of the present invention is to measure the position of an optical element disposed in a lens barrel in a non-contact manner with high resolution and high stability. Is to provide a simple optical device.

  A second object of the present invention is to provide an exposure apparatus capable of accurately transferring a mask pattern onto a photosensitive object.

  Based on the difference between the optical path length of the reference beam applied to the reference mirror and the optical path length of the measurement beam applied to the measurement object, the laser interferometer determines the position of the measurement object relative to the reference mirror ( Relative position). Therefore, the reference is the optical path length of the reference beam, and it is important that the optical path length of the optical path of the reference beam that is independent of the measuring beam does not change. That is, it is important that the distance from the separation optical element (such as a beam splitter) that separates the laser beam emitted from the light source into the length measurement beam and the reference beam is kept constant. The present invention has been made paying attention to this point, and employs the following configuration.

The invention according to claim 1 is for measuring a position of at least one of the optical elements; a lens barrel (52); one or more optical elements (M1 to M6) held in the lens barrel; An interferometer component (64x _i , 64y _i ) that constitutes a part of a laser interferometer used and is fixed to the lens barrel, and the interferometer component is emitted from a light source (80) An optical apparatus comprising at least a separation optical element (72) for separating a laser beam into a length measurement beam and a reference beam and a reference mirror (74) for reflecting the reference beam.

  According to this, the interferometer components constituting a part of the laser interferometer used for position measurement of at least one of the one or more optical elements held in the lens barrel are fixed to the lens barrel. ing. The interferometer component includes at least a separation optical element that separates a laser beam emitted from a light source into a measurement beam and a reference beam, and a reference mirror that reflects the reference beam. That is, an interferometer component including at least a separation optical element for determining an optical path independent of the measurement beam (optical path length) and a reference mirror among the optical paths of the reference beam is fixed to the lens barrel. By increasing the rigidity of the cylinder itself, the distance from the separation optical element to the reference mirror (positional relationship between the separation optical element and the reference mirror) can be maintained constant. As a result, the position of the optical element irradiated with the length measuring beam by the laser interferometer is accurately determined based on the difference between the optical path length of the reference beam irradiated to the reference mirror and the optical path length of the length measuring beam (static Measurement can be performed in a non-contact manner with high stability (with a higher resolution than a capacitance displacement sensor, etc.). In addition, the measurement stroke of the laser interferometer is usually much longer than the measurement stroke of a capacitive displacement sensor, etc., and the measurement stroke is insufficient with respect to the adjustment stroke of the optical element. There is no. Further, it is not necessary to use a large and heavy holding member as a holding member for holding the interferometer components, and it is sufficient to make the lens barrel a structure having a certain degree of rigidity, so that the size of the apparatus is not increased.

  In this case, as in the optical device according to claim 2, the interferometer component can further include at least one of a λ / 4 plate (76A, 76B) and a detector (78).

In each of the optical devices according to the first and second aspects, as in the optical device according to the third aspect, an optical element driving mechanism (46 ₁ to 46) that drives the optical element based on a measurement result of the laser interferometer. 46 ₆ ) may further be provided.

  The invention described in claim 4 is an exposure apparatus that irradiates the mask (R) with illumination light (EL) and transfers the pattern of the mask onto the photosensitive object (W) via the projection optical system (PO). An exposure apparatus comprising the optical apparatus according to claim 1 as the projection optical system.

  According to this, since the optical apparatus capable of measuring the position of at least one optical element held in the lens barrel with high resolution and stability in a non-contact manner is provided as a projection optical system, the measurement is performed. By adjusting the position and orientation of the optical element based on the result, it becomes possible to adjust the imaging characteristics of the projection optical system with high accuracy. By transferring the pattern onto the photosensitive object, the pattern can be accurately transferred onto the photosensitive object.

  In this case, as in the exposure apparatus according to claim 5, the projection optical system is a reflection optical system including only a reflection optical element, and the illumination light is EUV light having a wavelength of 5 to 20 nm. be able to.

  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 set in the Z-axis direction and in a plane perpendicular to the Z-axis direction 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 projects an image of a part of a 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 1 on 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 the dimensional direction (here, the Y-axis direction).

  The exposure apparatus 10 emits EUV light (light in the soft X-ray region) EL, reflects the EUV light EL from the light source apparatus 12, reflects the reticle R at a predetermined incident angle, for example, about 50 [mrad]. Illumination optical system including a bending mirror M that is bent so as to be incident on the pattern surface (the lower surface in FIG. 1 (the surface on the −Z side)) (note that the bending mirror M exists inside the lens barrel of the projection optical system PO). Although actually part of the illumination optical system), the reticle stage RST that holds the reticle R, and the EUV light EL reflected by the pattern surface of the reticle R is exposed to the exposed surface of the wafer W (the upper surface in FIG. A projection optical system PO that projects perpendicularly to the + Z side surface)), a wafer stage WST that holds the wafer W, and the like. The exposure apparatus 10 is actually housed in a vacuum chamber (not shown).

  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 this 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 the exposure beam.

  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. The EUV light EL emitted from the light source device 12 and passing through the illumination optical system (the EUV light EL reflected by the bending mirror M) illuminates the pattern surface of the reticle R as arc-slit illumination light.

  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. This multilayer film has a reflectance of about 70% for EUV light having a wavelength of 11 nm. 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, the EUV light including the circuit pattern information travels 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 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 the main control device 20 (see FIG. 7), and the main control device 20 uses the reticle interferometer 82R and the reticle focus sensor (13a, 13b). The reticle stage RST is driven via the reticle stage drive system 34 on the basis of the measured value of (), 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. Therefore, the EUV light EL that is reflected by the reticle R and includes information on the pattern formed on the reticle R is reduced to a quarter by the projection optical system PO and projected onto the wafer W, whereby the reticle R is projected onto the reticle R. The pattern is reduced to ¼ and transferred to the wafer W. The specific configuration of the projection optical system PO will be described in detail later.

  The wafer stage WST is disposed on a wafer stage base 60 disposed along the XY plane, and is levitated and supported on the wafer stage base 60 by a wafer stage drive system 62 including, 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 θ 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 64.

  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. The position of wafer stage WST is always detected by a wafer laser interferometer (hereinafter referred to as “wafer interferometer”) 82W arranged outside, 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.

  Further, the position of the wafer W in the Z-axis direction with respect to the lens barrel is measured by an oblique 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 main controller 20 (see FIG. 7), and the main controller 20 controls the wafer stage drive system 62, and the wafer stage WST. Position and orientation control in a 6-dimensional direction is performed.

  To measure the relative position of the alignment system ALG described later (so-called baseline measurement) at one end of the upper surface of wafer stage WST and the position where the pattern drawn on reticle R is projected onto the wafer W surface. 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. .

  Next, the projection optical system PO will be described in detail with reference to FIGS.

  FIG. 2 shows a schematic perspective view of the projection optical system PO. The projection optical system PO includes five partial lens barrels 152a, 152b, 152c, 152d, and 152e sequentially connected from top to bottom along the Z-axis direction, and a flange FLG provided between the partial lens barrels 152b and 152c. And a mirror M1, M2, M3, M4, M5, and M6 (see FIG. 3A, FIG. 3B, and FIG. 4) disposed inside the lens barrel 52. It is configured. On the side wall on the −Y side of the lens barrel 52, an opening 52a is formed to straddle both the partial lens barrel 152a and the partial lens barrel 152b. The partial lens barrels 152a to 152e and the flange FLG are formed of a material with less degassing such as stainless steel (SUS).

  The partial lens barrel 152a is provided with an overhanging portion 152f projecting to the outside at a part (−Z side and + Y side portion) of the outer peripheral surface in the vicinity of the lower end portion thereof, and a substantially cylindrical member whose upper surface is closed as a whole. Is formed by. The partial barrel 152a has a rectangular opening 52b penetrating vertically on the upper wall (+ Z side wall).

  The partial barrel 152b is formed of a cylindrical member having a slightly larger diameter than the partial barrel 152a, and is connected to the lower side (−Z side) of the partial barrel 152a. The flange portion FLG having a diameter larger than that of the other portion is connected to the vicinity of the lower end portion of the partial barrel 152b.

  The partial barrel 152c is formed of a cylindrical member having a slightly smaller diameter than the partial barrel 152b, and is connected to the lower side (−Z side) of the flange FLG.

  The partial barrel 152d is made of a cylindrical member having a slightly smaller diameter than the partial barrel 152c, and is connected to the lower side (−Z side) of the partial barrel 152c.

  The partial barrel 152e is formed of a cylindrical upper member having a slightly smaller diameter than the partial barrel 152d whose bottom is closed, and is connected to the lower side (−Z side) of the partial barrel 152d. Although not shown, an opening for allowing the EUV light EL to pass from the projection optical system PO toward the wafer W is formed in the bottom wall (the wall on the −Z side) of the partial barrel 152e.

  FIG. 3A shows a perspective view of the six mirrors M1 to M6 arranged in the lens barrel 52 as viewed obliquely from above, and FIG. 3B shows these six mirrors M1 to M1. M6 is shown in a perspective view as seen obliquely from below. As can be seen from these drawings, the six mirrors M1 to M6 are arranged in the order of the mirror M2, the mirror M4, the mirror M3, the mirror M1, the mirror M6, and the mirror M5 from the top. In FIGS. 3A and 3B, the reflecting surface of each mirror is hatched.

  In the present embodiment, the reflecting surfaces of the mirrors M1 to M6 each have a processing accuracy that is unevenness of about 1/50 to 1/60 of the exposure wavelength with respect to the design value, and the RMS value (standard deviation). Is set so that there is only a flatness error of 0.2 nm to 0.3 nm or less. The shape of the reflecting surface of each mirror is formed by alternately repeating measurement and processing.

  As can be seen from FIGS. 3A and 4, the upper surface of the mirror M <b> 1 is a rotationally symmetric reflecting surface such as a spherical surface or an aspherical surface, and the rotationally symmetric axis is substantially the optical axis AX of the projection optical system PO. It is a concave mirror whose position is adjusted to match. The mirror M1 is disposed inside the partial barrel 152c. The mirror M1 is held in the partial barrel 152c by a mirror holding mechanism 92, as shown in FIG. 5, which is a perspective view showing the partial barrel 152c with a part thereof broken away. The mirror M1 actually has a polygonal outer contour as shown in FIG. 3A. However, in FIG. 5, it is formed on a part of the outer peripheral surface for convenience of illustration. The outlines of the portions other than the reflected surfaces 65x and 65y are shown as if they were arcuate. Here, the reflecting surface 65x is a plane (a plane subjected to mirror finishing) perpendicular to the X axis formed in a part on the + X side of the outer circumferential surface of the mirror M1, and the reflecting surface 65y is the outer circumference of the mirror M1. A plane perpendicular to the Y-axis formed on a part of the surface on the + Y side (a plane subjected to mirror finishing).

The mirror holding mechanism 92 is provided on each of the parallel link mechanism 41 ₁ whose part is fixed to the inner surface of the partial barrel 152c and the upper surface of the inner ring 42 constituting the end effector of the parallel link mechanism 41 ₁ . Mirror holding members 44A, 44B, and 44C that hold three positions on the side surface of the mirror M1 are provided.

The parallel link mechanism 41 ₁ includes an outer ring 48 formed of an annular member constituting a base portion provided in a state inscribed in the inner surface of the partial barrel 152c, and an annular shape having a diameter slightly smaller than the outer ring 48. The inner ring 42 made of a member and disposed above the outer ring 48, the outer ring 48 and the inner ring 42 are connected to each other, and the inner ring 42 is relatively X, Y, Z relative to the outer ring 48. And a drive mechanism 46 for driving in the six-degree-of-freedom directions of the axial direction and θx (rotational direction about the X axis), θy (rotational direction about the Y axis), and θz (rotational direction about the Z axis).

  The drive mechanism 46 is configured by six links 110 having the same configuration, one end and the other end being connected to the outer ring 48 and the inner ring 42 via a spherical pair. As shown in FIG. 5, each link 110 includes a first shaft member 113 and a second shaft member 115 connected to or coupled to the first shaft member 113, and one end of the first shaft member 113 ( The lower end is attached to the outer ring 48 via a hinge 111 having the same degree of freedom of movement as that of the ball joint, and the other end (upper end) of the second shaft member 113 is attached to the inner ring 42 in the same manner as the ball joint. It is attached via a hinge (not shown) having a degree of freedom.

  In this case, at least one of the second shaft member 115 and the first shaft member 113 changes the length of the link 110, that is, the distance between the lower end of the first shaft member 113 and the upper end of the second shaft member 115. Possible actuators are provided. As such an actuator, it is conceivable to use a linear cylinder, a small motor, a piezoelectric element, or the like, but in this embodiment, a piezoelectric element is used as an example.

As can be seen from the above description, the parallel link mechanism 41 ₁ includes a stretchable link six, a parallel link mechanism called Stewart platform type.

  The mirror holding members 44A to 44C are arranged in a predetermined positional relationship on the upper surface (+ Z side surface) of the inner ring 42, and are divided into three locations on the outer peripheral surface of the mirror M1, for example, three equal parts on the outer periphery with a central angle of 120 ° Each point is held. Each of these mirror holding members 44 </ b> A to 44 </ b> C has a substantially inverted U shape, and is set so that the rigidity of the inner ring 42 in the radial direction is low.

  Each of the mirror holding members 44A to 44C and the mirror M1 are fixed by an adhesive or the like, so that the mirror M1 is held in a state in which a predetermined positional relationship is maintained with respect to the inner ring 42. .

  As described above, since the mirror M1 is held by the mirror holding members 44A to 44C having low rigidity in the radial direction of the inner ring 42, the mirror M1 is thermally expanded. Even in this case, substantially uniform thermal expansion occurs in each direction in the XY plane, and the contour shape of the outer peripheral surface is maintained in the original similar shape.

As shown in FIG. 5, it is provided in a state where the interferometer block 64x ₁ is embedded in the partial tube 152c as interferometer components facing the reflecting surface 65x of the mirror M1 constituting the X laser interferometer cage (see FIG. 6), the interferometer block 64y ₁ of facing the reflecting surface 65y as interferometer components constituting the Y laser interferometer mirror M1 is provided in a state embedded in the partial tube 152c .

As shown in FIG. 6, the interferometer block 64x ₁ is emitted from a light source 80 disposed outside the partial barrel 152c, and passes through a light transmission optical system (including a mirror and a beam splitter) not shown. And a polarization beam splitter 72 disposed on the optical path of the laser light traveling in the −X direction toward the inside of the partial lens barrel 152c, and a λ / 4 plate sequentially disposed on the −Z side of the polarization beam splitter 72 ( A quarter-wave plate) 76A, a reference mirror 74, a λ / 4 plate 76B disposed on the −X side of the polarizing beam splitter 72, and a detector 78 disposed on the + Z side of the polarizing beam splitter 72. Yes.

  As the light source 80, a dual-frequency laser using the Zeeman effect is used here. The light source 80 is frequency-stabilized, uses the Zeeman effect, has a different frequency by 2 to 3 MHz (and therefore has a different wavelength), and a first polarization component and a second polarization direction whose polarization directions are orthogonal to each other. A laser beam consisting of a circular beam with a Gaussian distribution including a polarization component is output. Here, it is assumed that the first polarization component is a horizontal polarization component, which is hereinafter referred to as “H component”. Further, the second polarization component is assumed to be a vertical polarization component, and hereinafter this will be referred to as “V component”.

  The polarization beam splitter 72 is an optical element that transmits a predetermined polarization component and reflects a polarization component orthogonal to the predetermined polarization component. For example, the polarization beam splitter 72 transmits the V component from the light source 80 as it is and reflects the H component. The component and the H component are separated.

In this case, X laser interferometer for measuring the X-axis direction position of the mirror M1 to (X position) by the above interferometer block 64x ₁ and the light source 80 is constituted. According to this X laser interferometer, the laser light emitted from the light source 80 is incident on the polarization beam splitter 72 via a light transmission optical system (not shown), and the polarization beam splitter 72 causes the V component, the H component, and the like. Separated. In this case, the V component transmitted through the polarization beam splitter 72 is a length measurement beam, and the H component reflected by the polarization beam splitter 72 is a reference beam.

  The reference beam (H component) separated by the polarization beam splitter 72 is transmitted through the λ / 4 plate 76A, converted into circularly polarized light, reflected by the reference mirror 74, and then passed through the λ / 4 plate 76A. It is transmitted again in the opposite direction. Thereby, the reference beam (H component) is converted into a direction (X-axis direction) whose polarization direction is orthogonal to the polarization direction (Y-axis direction) at the time of incidence on the λ / 4 plate 76A and from the λ / 4 plate 76A. The light is output, enters the polarization beam splitter 72, passes through the polarization beam splitter 72, and then enters the detector 78.

  On the other hand, the length measurement beam (V component) separated by the polarization beam splitter 72 is transmitted through the λ / 4 plate 76B, converted into circularly polarized light, reflected by the reflecting surface 65x of the mirror M1, and then λ / 4. The light passes again through the plate 76B in the opposite direction. Thereby, the measurement beam is converted into a direction (Y-axis direction) whose polarization direction is orthogonal to the polarization direction (Z-axis direction) at the time of incidence on the λ / 4 plate 76B, and is output from the λ / 4 plate 76B. The light enters the polarization beam splitter 72, is reflected by the polarization beam splitter 72, is synthesized coaxially with the reference beam, travels on the same optical path, and enters the detector 78.

  The detector 78 includes a polarizer (not shown) and a photoelectric conversion element inside the detector 78. The polarizer is a length measuring beam (the polarization direction (vibration direction) is a component in the Y-axis direction) synthesized coaxially by the polarization beam splitter 72. ) And the reference beam (the polarization direction (vibration direction) is a component in the X-axis direction) and the polarization angle is set to a direction of 45 °, whereby interference light of both components is given to the photoelectric conversion element. It is supposed to be. This photoelectric conversion element supplies an electric signal (interference signal) obtained by photoelectrically converting both components of interference light to a signal processing system (not shown).

  This signal processing system is supplied with a reference signal for phase detection from the light source 80, and the signal processing system performs an operation using the reference signal to obtain the X position of the mirror M1. Note that details of the signal processing by the signal processing system are performed by a well-known method regarding the heterodyne interferometer, and thus detailed description thereof is omitted.

The interferometer block 64y ₁ is configured in the same manner as the interferometer block 64x ₁ . The interferometer block 64y ₁ and the light source 80 described above constitute a Y laser interferometer that measures the position (Y position) of the mirror M1 in the Y-axis direction. That is, the laser light from the light source 80 is incident on the interferometer block 64y ₁ through a light transmission optical system (not shown) provided outside the partial barrel 152c (consisting of a beam splitter, a mirror, etc.). and, in the same manner as the interferometer block 64x ₁ by the interferometer block 64y _1, Y position of the mirror M1 is measured.

Returning to FIG. 3A, the position of the mirror M2 is adjusted so that its lower surface is a rotationally symmetric reflecting surface such as a spherical surface or an aspherical surface, and its rotationally symmetric axis coincides with the optical axis AX of the projection optical system PO. (See FIGS. 3B and 4). The mirror M2 is held in the partial barrel 152a of FIG. 2 by a holding mechanism similar to the holding mechanism 92 that holds the mirror M1 described above, and is similar to the parallel link mechanism 41 ₁ that constitutes the holding mechanism. The parallel link mechanism 41 ₂ (see FIG. 7) having the configuration can be driven in the direction of six degrees of freedom. Similarly to the mirror M1, the mirror M2 also measures the position in the X-axis direction and the position in the Y-axis direction by the X interferometer and the Y interferometer, respectively. The X interferometer and the Y interferometer are respectively configured by interferometer blocks 64x ₂ and 64y ₂ (see FIG. 7) and a light source 80 provided in the partial lens barrel 152a as described above.

As shown in FIGS. 3A, 3B, and 4, the mirror M3 is a convex mirror whose upper surface is a reflecting surface, and is located away from the optical axis AX of the projection optical system PO. Is arranged. However, as shown in FIG. 4, the reflecting surface of the mirror M3 is a part of a rotationally symmetric surface such as a spherical surface or an aspherical surface indicated by a broken line 94a, and the rotationally symmetric axis substantially coincides with the optical axis AX. The position of the mirror M3 is adjusted to the position. This mirror M3 is held in the partial barrel 152b of FIG. 2 by a holding mechanism similar to the holding mechanism 92 that holds the mirror M1 described above, and is similar to the parallel link mechanism 41 ₁ that constitutes the holding mechanism. The parallel link mechanism 41 ₃ (see FIG. 7) having the configuration can be driven in the direction of six degrees of freedom. Similarly to the above-described mirror M1, the mirror M3 also measures the position in the X-axis direction and the position in the Y-axis direction by the X interferometer and the Y interferometer, respectively. The X interferometer and the Y interferometer are respectively configured by interferometer blocks 64x ₃ and 64y ₃ (see FIG. 7) and a light source 80 provided in the partial barrel 152b as described above.

3A, 3B and 4, the mirror M4 is a concave mirror whose lower surface is a reflecting surface, and is greatly deviated from the optical axis AX of the projection optical system PO. Placed in position. However, as shown in FIG. 4, the reflecting surface of the mirror M4 is a part of a rotationally symmetric surface such as a spherical surface or an aspherical surface indicated by a broken line 94b, and its rotational symmetry axis substantially coincides with the optical axis AX. The position of the mirror M4 is adjusted to the position. The mirror M4 is held in the partial barrel 152a of FIG. 2 by a holding mechanism similar to the holding mechanism 92 that holds the mirror M1 described above, for example, with one link protruding from the overhanging portion 152f. The parallel link mechanism 41 ₄ (see FIG. 7) having the same configuration as the above-described parallel link mechanism 41 ₁ constituting the mechanism can be driven in the direction of 6 degrees of freedom. Similarly to the above-described mirror M1, the mirror M4 also measures the position in the X-axis direction and the position in the Y-axis direction by the X interferometer and the Y interferometer, respectively. The X interferometer and Y interferometer are configured by interferometer blocks 64x ₄ and 64y ₄ (see FIG. 7) and a light source 80, respectively, provided in the partial barrel 152b in the same manner as described above.

As shown in FIG. 3A, FIG. 3B, and FIG. 4, the mirror M5 has a generally horseshoe shape as a whole, the upper surface of which is a reflection surface and a notch is formed in a part of the reflection surface. It is a convex mirror. The mirror M5 has a reflection surface that is part of a rotationally symmetric surface such as a spherical surface or an aspherical surface, and the position of the mirror M5 is adjusted so that the rotationally symmetric axis substantially coincides with the optical axis AX of the projection optical system PO. Yes. In the mirror M5, the above-described notch serving as the optical path of the illumination light EL is formed in a portion on the −Y side from the optical axis AX. The mirror M5, within a partial tube 152e 2 is held by the same holding mechanism and the holding mechanism 92 for holding the mirror M1 described above, similar to the parallel link mechanism 41 ₁ of the aforementioned constituting the holding mechanism The parallel link mechanism 41 ₅ (see FIG. 7) having the configuration can be driven in the direction of six degrees of freedom. Similarly to the mirror M1, the mirror M5 is also configured to measure the position in the X-axis direction and the position in the Y-axis direction by the X interferometer and the Y interferometer, respectively. The X interferometer and the Y interferometer are respectively configured by interferometer blocks 64x ₅ and 64y ₅ (see FIG. 7) and a light source 80 provided in the partial barrel 152e in the same manner as described above.

As shown in FIGS. 3A, 3B, and 4, the mirror M6 has a substantially horseshoe shape as a whole in which the lower surface is a reflecting surface and a notch is formed in a part thereof. It is a concave mirror. The mirror M6 has a reflection surface that is part of a rotationally symmetric surface such as a spherical surface or an aspherical surface, and the position of the mirror M6 is adjusted so that the rotationally symmetric axis substantially coincides with the optical axis AX of the projection optical system PO. Yes. In the mirror M6, the above-described notch serving as the optical path of the illumination light EL is formed on the + Y side of the optical axis AX. The mirror M6 is held in the partial barrel 152d in FIG. 2 by a holding mechanism similar to the holding mechanism 92 that holds the mirror M1 described above, and is similar to the parallel link mechanism 41 ₁ that constitutes the holding mechanism. The parallel link mechanism 41 ₆ (see FIG. 7) having the configuration can be driven in the direction of six degrees of freedom. Similarly to the above-described mirror M1, the mirror M6 also measures the position in the X-axis direction and the position in the Y-axis direction by the X interferometer and the Y interferometer, respectively. The X interferometer and Y interferometer are configured by interferometer blocks 64x ₆ and 64y ₆ (see FIG. 7) and a light source 80, respectively, provided in the partial barrel 152d as described above.

In this embodiment, as shown in FIG. 7, the positional information of the mirror M1 measured by the interferometer blocks 64x ₁ and 64y ₁ and the positional information of the mirror M2 measured by the interferometer blocks 64x ₂ and 64y ₂ , Position information of the mirror M3 measured by the interferometer blocks 64x ₃ and 64y ₃ , position information of the mirror M4 measured by the interferometer blocks 64x ₄ and 64y ₄ , measured by the interferometer blocks 64x ₅ and 64y ₅ The position information of the mirror M5 and the position information of the mirror M6 measured by the interferometer blocks 64x ₆ and 64y ₆ are supplied to the main controller 20, respectively. The main controller 20 adjusts the positions of the mirrors M1 to M6 in the X axis direction and the Y axis direction via the parallel link mechanisms 41 _{1 to} 41 ₆ based on the position information of the mirrors M1 to M6. .

  Here, the operation of the projection optical system PO configured as described above will be described with reference to FIG. The EUV light EL emitted from the light source device 12 and incident on the inside of the lens barrel 52 through the opening 52 a formed in the lens barrel 52 of the projection optical system PO is emitted from the illumination optical system disposed in the lens barrel 52. The light is reflected substantially upward by the bending mirror M constituting a part, and enters the reticle R through the opening 52b of the lens barrel 52 at a predetermined incident angle. Then, the EUV light EL reflected by the pattern surface of the reticle R is reflected by the mirror M1 and collected on the reflection surface of the mirror M2. Next, the EUV light EL reflected by the reflecting surface of the mirror M2 is sequentially reflected by the mirrors M3 and M4, passes through the notch of the mirror M6, enters the mirror M5, and is reflected by the reflecting surface of the mirror M5. Thereafter, the EUV light EL reflected by the mirror M5 is reflected by the mirror M6, and is irradiated onto the wafer W through the notch of the mirror M5 as a pattern imaging light beam.

  FIG. 7 schematically shows the main configuration of the control system of the exposure apparatus 10 of the present embodiment. This control system is mainly configured of a main controller 20 that controls the entire apparatus in an integrated manner.

  Next, the operation of the exposure process by the exposure apparatus 10 of the present embodiment configured as described above will be described.

  First, reticle R is transported by a reticle transport system (not shown) and held on reticle stage RST in the loading position. Next, main controller 20 (see FIG. 7) controls the positions of wafer stage WST and reticle stage RST, and a projection image of a reticle alignment mark (not shown) formed on reticle R onto the surface of wafer W is a space. The projection position of the reticle pattern image on the surface of the wafer W is obtained based on the detection result and the measurement values of the interferometers 82R and 82W. That is, reticle alignment is performed.

  Next, main controller 20 moves wafer stage WST so that aerial image measuring instrument FM is positioned directly below alignment system ALG, and the detection signal of alignment system ALG and the measured value of wafer interferometer 82W at that time are detected. Based on the above, the projection position of the pattern image of the reticle R onto the wafer W surface and the relative distance between the alignment system ALG, that is, the baseline of the alignment system ALG are obtained.

  When the baseline measurement is completed, the main controller 20 performs so-called EGA wafer alignment, and obtains the position coordinates of all shot areas on the wafer W.

  Then, step-and-scan exposure is performed using the EUV light EL as exposure illumination light as follows. That is, main controller 20 monitors the position information from wafer interferometer 82W according to the position information of each shot area on wafer W obtained as a result of the wafer alignment, and causes wafer stage WST to expose the first shot area. And the reticle stage RST is moved to the scan start position (acceleration start position), and scanning exposure of the first shot is performed. At the time of this scanning exposure, main controller 20 drives reticle stage RST and wafer stage WST in opposite directions, and the speeds of both stages so that the speed ratio of the two accurately matches the projection magnification of projection optical system PO. Is controlled to perform exposure (reticle pattern transfer). Thereby, a transfer image of a circuit pattern of, for example, 25 mm (width) × 50 mm (length in the scanning direction) is formed in the first shot region on the wafer W.

  When scanning exposure of the first shot area is completed as described above, main controller 20 performs stepping operation between shots to move wafer stage WST to a scanning start position (acceleration start position) for exposure of the second shot area. I do. Then, scanning exposure of the second shot area is performed in the same manner as described above. Thereafter, the same operation is performed after the third shot area.

  In this way, the stepping operation between shots and the scanning exposure operation for the shots are repeated, and the pattern of the reticle R is transferred to all shot regions on the wafer W by the step-and-scan method.

  Here, during the above scanning exposure and alignment, the distance between the wafer W surface and the projection optical system PO and the inclination with respect to the XY plane are measured by the wafer focus sensor (14a, 14b), and the main controller 20 measures the surface of the wafer W. Wafer stage WST is controlled so that the distance between the projection optical system PO and the parallelism is always constant. Further, in main controller 20, the distance between projection optical system PO during exposure (during reticle pattern transfer) and pattern surface of reticle R is always constant based on the measurement values of reticle focus sensors (13a, 13b). The reticle stage RST and wafer stage WST are synchronously moved along the Y-axis direction while adjusting the position of the reticle R in the optical axis direction (Z direction) of the projection optical system PO so as to be maintained.

  Further, in the exposure apparatus 10 of the present embodiment, for example, based on an operator's instruction, the main controller 20 adjusts predetermined imaging characteristics of the projection optical system PO. As a premise for adjusting the imaging characteristics of the projection optical system, it is necessary to accurately measure the imaging characteristics. As the measurement method, for example, measurement is performed by measuring a resist image obtained by performing exposure using a measurement mask on which a predetermined measurement pattern is formed and developing a wafer on which a projection image of the measurement pattern is transferred and formed. A method (printing method) for calculating imaging characteristics based on the result is mainly employed.

When the calculation result of the imaging characteristic is input by the operator, the main controller 20 performs a predetermined calculation to adjust the imaging characteristic of the projection optical system PO to a desired state. The driving amounts (including zero) in the X-axis and Y-axis directions of M1 to M6 are calculated, and the positions of the mirrors M1 to M6 are adjusted via the parallel link mechanisms 41 _{1 to} 41 ₆ according to the calculation results. In this adjustment, the main controller 20 determines the position information of the mirror M1 measured by the interferometer blocks 64x ₁ and 64y ₁ , the position information of the mirror M2 measured by the interferometer blocks 64x ₂ and 64y ₂ , and the interference. Position information of the mirror M3 measured by the meter blocks 64x ₃ and 64y ₃ , position information of the mirror M4 measured by the interferometer blocks 64x ₄ and 64y ₄ , mirror measured by the interferometer blocks 64x ₅ and 64y ₅ M5 position information, based on the interferometer block 64x _6, position information of the mirror M6 measured by 64y _6, as mirror M1~M6 each position coincides with the target position, the parallel link mechanism 41 _{1-41 6} is feedback controlled. Thereby, the imaging characteristic of the projection optical system PO is adjusted to a desired state.

In the description so far, the positions of the mirrors M1 to M6 in the X-axis direction and the Y-axis direction are measured by the interferometer blocks 64x _i and 64y _i (i = 1 to 6). The at least one specific mirror of the mirrors M1 to M6 is provided with at least one interferometer block for measuring the position in the Z-axis direction, and the position of the specific mirror in the Z-axis direction, further to the XY plane More preferably, the tilt is measured. In such a case, the main controller 20 adjusts the position of the specific mirror in the Z-axis direction, and further, the tilt (tilt) with respect to the XY plane, so that the imaging characteristics of the projection optical system PO can be improved with high accuracy. Fine adjustment is possible.

  As described above in detail, according to the exposure apparatus 10 of the present embodiment, the EUV light EL having an extremely short wavelength is used as the exposure light, and the pattern of the reticle R is changed to the wafer via the all-reflection projection optical system PO having no chromatic aberration. Since it is transferred onto W, the fine pattern on reticle R can be transferred to each shot area on wafer W with high accuracy. Specifically, a fine pattern with a minimum line width of about 70 nm can be transferred with high accuracy.

Further, interferometer blocks 64x _i and 64y _i (i = 1 to 6) constituting a part of the laser interferometer used for position measurement of the mirrors M1 to M6 held in the lens barrel 52 are fixed to the lens barrel 52. Each of these interferometer blocks 64x _i and 64y _i includes a beam splitter 72 that separates the laser light emitted from the light source 80 into a measurement beam and a reference beam, and a reference that reflects the reference beam. A mirror 74 and the like are included. That is, interferometer blocks 64x _i and 64y _i including a beam splitter 72 and a reference mirror 74 that determine an optical path independent of the measurement beam among the optical paths of the reference beam and the reference mirror 74 are fixed to the lens barrel 52. Therefore, by increasing the rigidity of the lens barrel 52 itself, the distance from the beam splitter 72 to the reference mirror 74 (the positional relationship between the beam splitter 72 and the reference mirror 74) can be maintained constant. As a result, the position of the mirror irradiated with the measurement beam by each laser interferometer is accurately determined based on the difference between the optical path length of the reference beam irradiated to the reference mirror 74 and the optical path length of the measurement beam ( Measurement can be performed in a non-contact manner with high stability (with a higher resolution than a capacitance displacement sensor). Also, the measurement stroke of the laser interferometer is usually much longer than the measurement stroke of a capacitive displacement sensor, etc., and the measurement stroke is not sufficient relative to the mirror adjustment stroke. Absent. Further, it is not necessary to use a large and heavy holding member as a holding member for holding the interferometer block, and it is sufficient to make the lens barrel a structure having a certain degree of rigidity, so that the size of the apparatus is not increased.

  In the above embodiment, a configuration in which the positions of all six mirrors are measured with a laser interferometer is adopted. However, the present invention is not limited to this, and measurement of at least one of the mirrors is performed. I hope it can be done. Therefore, the measurement target mirror and the number of mirrors can be arbitrarily set.

  In the above-described embodiment, the case where the beam splitter 72, the reference mirror 74, the λ / 4 plates 76A and 76B, and the detector 78 are provided as the interferometer block has been described. However, the present invention is not limited to this, and the interference is not limited. The meter block only needs to include at least a beam splitter and a reference mirror.

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. Of course, since one or more optical elements are sufficient, the present invention can be suitably applied to a projection optical system having three or less optical elements.

  In the above embodiment, the case where the parallel link mechanism is employed as the optical element driving mechanism has been described. However, the present invention is not limited to this, and for example, any mechanism capable of driving the optical element. It is possible to employ various mechanisms. Further, a configuration in which the operator adjusts the position of the mirror based on the measurement value of the laser interferometer may be employed.

  In the above embodiment, the case where the position of the mirror is measured using the laser interferometer has been described. However, for example, the position of the mirror may be measured using a linear encoder instead of the laser interferometer. For example, as shown in FIG. 8A, a transmissive linear scale 99 is provided on the mirror M1, and a laser beam sending system 98A for sending the laser beam to the partial barrel 152c and a laser beam receiving system 98B for receiving the laser beam. For example, the position of the mirror M1 in the X-axis direction or the Y-axis direction in FIG. 8A may be measured. According to the configuration of FIG. 8A, since the laser beam transmitting system 98A and the laser beam receiving system 98B are provided in the partial lens barrel 152c, the rigidity of the partial lens barrel 152c is set to be somewhat high as in the above embodiment. By doing so, the position of the mirror M1 in the X-axis direction or the Y-axis direction can be accurately measured.

  Further, as shown in FIG. 8B, a reflective linear scale 99 ′ is provided on the side surface of the mirror M1, and laser light is sent to the partial lens barrel 152c toward the reflective linear scale 99 ′. An optical system 98A ′ and a laser light receiving system 98B ′ that receives the laser light reflected by the linear scale 99 ′ may be provided, and the position of the mirror M1 in the Z-axis direction in FIG. 8B may be measured. Also in FIG. 8B, as in the case of FIG. 8A, the rigidity of the partial barrel 152c provided with the laser transmission system 98A ′ and the laser light reception system 98B ′ is set to be somewhat high. Thus, the Z position of the mirror M1 can be accurately measured. In this case, as shown in FIG. 8B, the position of the mirror M1 can be measured even if the window glass 97 is fitted into the partial lens barrel 152c. This is particularly effective when replacing with a predetermined gas. Note that this modification is not limited to the mirror M1 and can be applied to other mirrors.

  In the above embodiment, the case where the optical apparatus of the present invention is employed as the projection optical system constituting the exposure apparatus has been described. However, the present invention is not limited to this, and for example, the optical apparatus of the present invention is used. It may be employed as an illumination optical system. In addition to the exposure apparatus, any other optical apparatus having an optical element in the lens barrel can be employed in various apparatuses, and in any case, the same effect as in the above embodiment can be obtained. Is possible.

  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 (Synchrotron Orbital Radiation), betatron light source, discharged light source, X-ray laser, etc. Also good.

  As described above, the optical apparatus of the present invention is suitable for use as an illumination optical system or projection optical system of an exposure apparatus. The exposure apparatus of the present invention is suitable for irradiating a mask with illumination light and transferring the mask pattern onto the photosensitive object via a projection optical system.

It is a figure which shows schematic structure of the exposure apparatus which concerns on one Embodiment of this invention. It is a schematic perspective view of the projection optical system of FIG. FIG. 3A and FIG. 3B are diagrams for explaining the arrangement of the mirrors constituting the projection optical system. It is a figure for demonstrating the effect | action of the mirror which comprises a projection optical system. It is a perspective view which fractures | ruptures and shows a part of partial barrel 152c. It is a figure which shows the structure of the laser interferometer used for the position measurement of a mirror. It is a block diagram which shows the control system of one Embodiment. FIG. 8A and FIG. 8B are diagrams for explaining a modification of the embodiment.

Explanation of symbols

46 _{1 to} 46 ₆ ... parallel link mechanism (optical element driving mechanism), 52 ... barrel, 64x _i , 64y _i ... interferometer block (interferometer component), 72 ... polarization beam splitter (separation optical element), 74 ... Reference mirror, 76A, 76B ... λ / 4 plate, 78 ... detector, 80 ... light source, EL ... EUV light (illumination light), M1 to M6 ... mirror (optical element), PO ... projection optical system, R ... reticle (mask) ), W: photosensitive object (wafer).

Claims (5)

With a lens barrel;
One or more optical elements held in the lens barrel;
A part of a laser interferometer used for position measurement of at least one of the optical elements, and an interferometer component fixed to the lens barrel;
The interferometer component includes at least a separation optical element that separates a laser beam emitted from a light source into a length measurement beam and a reference beam, and a reference mirror that reflects the reference beam. .   The optical apparatus according to claim 1, wherein the interferometer component further includes at least one of a λ / 4 plate and a detector.   The optical apparatus according to claim 1, further comprising an optical element driving mechanism that drives the optical element based on a measurement result of the laser interferometer. An exposure apparatus that irradiates a mask with illumination light and transfers a pattern of the mask onto a photosensitive object via a projection optical system,
An exposure apparatus comprising the optical apparatus according to claim 1 as the projection optical system. The projection optical system is a reflective optical system composed only of reflective optical elements,
The exposure apparatus according to claim 4, wherein the illumination light is EUV light having a wavelength of 5 to 20 nm.

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