JP2005276933A - Optical member holding device, optical unit and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform high precision minute driving of an optical component by an optical member holding device, an optical unit and an aligner. <P>SOLUTION: In a parallel link mechanism 41<SB>1</SB>constituting a holding device 92, holding mechanisms (44A to 44C) holding the optical member M1 are installed in an end effector 42 and a linking mechanism 46 is arranged for driving the end effector to a plurality of directions of degree of freedom to a base 48. Links 47A to 47F constituting the link mechanism have piezoelectric elements and displacement reduction mechanisms which are connected to one end in an expansion/contraction direction of the piezoelectric elements, reduce expansion/contraction displacement of the piezo-electric element, and transmit it to the end effector. In the holding device, the respective links can be made small and light, expansion/contraction of the piezoelectric element is reduced by the displacement reduction mechanism and is transmitted to the end effector. The optical member is integrally driven with the end effector. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical member holding device, an optical unit, and an exposure apparatus, and more specifically, an optical member holding device that holds an optical member movably in a predetermined direction, an optical unit including the optical member holding device, and the optical unit. Is provided as an optical projection system.

  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 ultrahigh pressure mercury lamp or an ultraviolet ray such as KrF excimer laser light (wavelength 248 nm) Light was used. Recently, in order to obtain higher resolution (resolution), an exposure apparatus using far ultraviolet light such as ArF excimer laser light (wavelength 193 nm) or vacuum ultraviolet light such as F ₂ laser light (wavelength 157 nm) as an exposure beam. Development is also underway. 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.

  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) ) For adjusting the position and orientation of at least a part of the optical members (hereinafter referred to as “movable optical members”) constituting the projection optical system (hereinafter referred to as “ Generally referred to as “position and orientation adjusting means”. As this position and orientation adjustment means, for example, one using a parallel link type adjustment mechanism employing a parallel link mechanism is known.

  As a conventional projection optical system, a refracting system or a catadioptric system is mainly used. Therefore, the light flux is at least zero times (in the case of a refracting system) within the projection optical system, and at most two to three times (catadioptric system). In this case, the light beam is merely deflected, but the light beam is folded back and forth, for example, in a zigzag manner inside the reflection system employed in the EUV exposure apparatus or the like. For this reason, when the conventional parallel link type adjustment mechanism is adopted as a means for adjusting the position and orientation of a reflection optical member such as a projection optical system of an EUV exposure apparatus, the parallel link type adjustment mechanism and the optical member, illumination light, etc. May interfere with each other, and as a result, it may be difficult to construct a projection optical system having desired optical performance.

  Further, as the resolution required for the projection optical system increases year by year, it is essential to adjust the position and orientation of the movable optical member with higher accuracy by the position and orientation adjustment means.

The present invention has been made under the circumstances described above. From a first viewpoint, the present invention is an optical member holding device that holds the optical member (M1) so as to be movable in a predetermined direction, and holds the optical member. A parallel link having a mechanism (44A to 44C); a link mechanism (46) in which the holding mechanism is provided in the end effector (42), and the end effector is driven in a direction of multiple degrees of freedom with respect to the base (48). mechanism (41 _1); provided with, each of the links constituting the link mechanism, the telescopic drive elements (55A), connected in series expansion and contraction direction of the one end of the driving element, the telescopic displacement of the drive element An optical member holding device having a displacement reducing mechanism (59) that reduces and transmits the reduced effect to the end effector.

  According to this, the parallel link mechanism constituting the holding device of the present invention is a link in which the holding mechanism for holding the optical member is provided in the end effector, and the end effector is driven in the direction of multiple degrees of freedom with respect to the base. Each link constituting the link mechanism is connected in series to a telescopic drive element and one end of the drive element in the direction of expansion and contraction, and the end effector is reduced by reducing the expansion and contraction displacement of the drive element. And a displacement reduction mechanism for transmitting to each of them. For this reason, in the optical member holding device of the present invention, each link and thus the link mechanism can be set to be small and light, and the expansion and contraction of the drive element is reduced by the displacement reduction mechanism and transmitted to the end effector. And the optical member are driven together. Therefore, the optical member can be finely driven with high accuracy, and the parallel link mechanism can be arranged without any trouble even in a space where the light beam is folded back in a zigzag shape.

  In this case, the link between the end effector and the base of each link is a gimbal joint that allows rotation about two rotation axes orthogonal to each other in a plane orthogonal to the longitudinal direction constituting the link. Can be provided respectively.

  Various configurations can be adopted as each gimbal joint. For example, each gimbal joint is provided at a connection portion of the link with the end effector or the base, and is arranged in the longitudinal direction of the link. The first narrow portion and the second narrow portion that are orthogonal to each other at different positions can be formed by members formed respectively. In this case, the displacement reduction mechanism can be integrally formed with the member.

  In the optical member holding device of the present invention, the drive element may be a piezo element.

  The optical member holding device of the present invention may further include a sensor that detects the amount of expansion / contraction of the drive element. In this case, the sensor may be a capacitance sensor.

  In the optical member holding device of the present invention, the parallel link mechanism can drive the optical member in the direction of six degrees of freedom.

  In the optical member holding device of the present invention, the displacement reduction mechanism can be a mechanism using the lever principle.

  From a second aspect, the present invention is an optical unit comprising a plurality of optical members, wherein at least one of the plurality of optical members is held by the optical member holding device of the present invention. .

  According to this, since at least one of the plurality of optical members constituting the optical unit is held by the optical member holding device according to the present invention capable of minutely driving the optical member with high accuracy, the optical unit It is possible to finely adjust the optical member in the inside, and thus to adjust the optical characteristics of the optical unit with high accuracy.

  In this case, all of the plurality of optical members can be held by the optical member holding device of the present invention.

  According to a third aspect of the present invention, there is provided an exposure apparatus for transferring a pattern formed on a mask onto an object via a projection optical system, the exposure apparatus comprising the optical unit of the present invention as the projection optical system. is there.

  According to this, since the projection optical system includes an optical unit capable of adjusting the optical characteristics with high accuracy, the optical characteristics of the projection optical system are adjusted, and then the adjusted projection optical system is used. Thus, the pattern formed on the mask can be transferred onto the object with high accuracy.

  In this case, a reflective mask is used as the mask, all the optical members constituting the optical unit are mirrors, and the reflective surface of each mirror is a multilayer film for reflecting extreme ultraviolet light on the surface thereof. Can be provided.

  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 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 a 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]. The illumination optical system including the 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 bending mirror M is disposed inside the lens barrel of the projection optical system PO). Although actually present, it is part of the illumination optical system), reticle stage RST that holds reticle R, and illumination light (EUV light) EL reflected by the pattern surface of reticle R is exposed to wafer W. A projection optical system PO as an optical unit that projects perpendicularly to a 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 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, 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 the main control device 20 (see FIG. 9), 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 unit 34 based on the measured value of (), so that the position and posture 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 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 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. 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 of the projection optical system PO 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. 9), 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.

  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).

  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 divided lens barrels 152a, 152b, 152c, 152d, and 152e that are sequentially connected from top to bottom along the Z-axis direction, and a flange FLG provided between the divided lens barrels 152b and 152c. And a mirror M1, M2, M3, M4, M5, and M6 as optical members disposed inside the lens barrel 52 (see FIGS. 3A, 3B, and 4) It is comprised including. On the side wall on the −Y side of the lens barrel 52, an opening 52a is formed so as to straddle both the divided lens barrel 152a and the divided lens barrel 152b. The split lens barrels 152a to 152e and the flange FLG are formed of a material with less degassing such as stainless steel (SUS).

  The split 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 generally cylindrical member whose upper surface is closed as a whole. Is formed by. The divided lens barrel 152a has a rectangular opening 52b penetrating vertically on the upper wall (+ Z side wall).

  The divided lens barrel 152b is formed of a cylindrical member having a slightly larger diameter than the divided lens barrel 152a, and is connected to the lower side (−Z side) of the divided lens 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 divided lens barrel 152b.

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

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

  The split lens barrel 152e is formed of a cylindrical member having a bottom surface that is slightly smaller in diameter than the split lens barrel 152d, and is connected to the lower side (−Z side) of the split lens 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 (-Z side wall) of the divided lens 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 mirror M1 has a rotationally symmetric reflecting surface such as a spherical surface or an aspherical surface, and its 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 split barrel 152c. The mirror M1 is held in the divided lens barrel 152c by a mirror holding device 92 as an optical member holding device, as shown in FIG. In addition, the mirror M1 has a reference plane (a mirror-finished plane) 65x perpendicular to the X axis formed on a part of the side surface on the + X side, and a part of the side surface on the + Y side includes Y A reference plane (a plane subjected to mirror finishing) 65y perpendicular to the axis is formed.

As shown in FIG. 5, the mirror holding device 92 includes a parallel link mechanism 41 ₁ , a part of which is fixed to the inner surface of the divided lens barrel 152 c, and an inner ring that constitutes an end effector of the parallel link mechanism 41 _1. Mirror holding members 44A, 44B, and 44C that are provided on the upper surface of 42 and hold three positions on the side surface of the mirror M1.

The parallel link mechanism 41 ₁ is configured on the projecting portion of the annular inwardly projecting at the lower portion of the divided tube 152c, a base consisting of an annular member placed over the three adjustment washers WR An outer ring 48, an annular member having a diameter slightly smaller than the outer ring 48, and an end effector disposed above the outer ring 48, and the outer ring 48 and the inner ring 42, The inner ring 42 is connected to each other and the inner ring 42 is rotated with respect to the outer ring 48 in the X, Y, Z axis directions, θx (rotational direction around the X axis), θy (rotational direction around the Y axis), θz (rotation around the Z axis). And a link mechanism 46 that drives in the direction of 6 degrees of freedom. Note that by changing the thickness of the adjustment washer WR, the attitude of the outer ring 48 with respect to the annular protrusion can be adjusted.

  The link mechanism 46 includes six links 47 </ b> A to 47 </ b> F having the same configuration in which one end and the other end are connected to the outer ring 48 and the inner ring 42. Each of the links 47A to 47F is configured to be stretchable with respect to the longitudinal direction thereof, and the inner ring 42 is driven in the direction of 6 degrees of freedom with respect to the outer ring 48 by expanding and contracting each link. It has become. The specific configuration of the links 47A to 47F will be described in detail later.

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. In the present embodiment, a holding mechanism that holds the mirror M1 is configured by these mirror holding members 44A to 44C.

  Each of the mirror holding members 44A to 44C and the mirror M1 are fixed by a mechanical clamping mechanism, whereby the mirror M1 is held in a state in which a predetermined positional relationship is maintained with respect to the inner ring 42. ing.

  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.

Further, as shown in FIG. 5, an opening 64x is formed in a part of the split lens barrel 152c so as to face the reference plane 65x of the mirror M1, and the split lens barrel faces the reference plane 65y of the mirror M1. An opening 64y is formed in part of 152c. In a state where the projection optical system PO is mounted on the exposure apparatus, the length measurement beams from the laser interferometers 63X ₁ and 63Y ₁ (not shown in FIG. 5, refer to FIG. 9) installed outside the projection optical system PO are opened. The measurement beams irradiated to the reference planes 65x and 65y of the mirror M1 and reflected by the reference planes 65x and 65y of the mirror M1 are detected by the detectors in the laser interferometers 63X ₁ and 63Y ₁ through 64x and 64y. Thus, the XY position of the mirror M1 is always detected with a resolution of about 0.5 to 1 nm, for example.

  Here, the configuration of the six links 47A to 47F constituting the link mechanism 46 will be described in detail. As shown in FIG. 5, these six links are arranged in a state in which a link 47A and a link 47B, a link 47C and a link 47D, and a link 47E and a link 47F are paired.

  In FIG. 6A, the link 47A and the link 47B are taken out and shown together with the block-shaped connecting member 51 and the block-shaped fixing members 57A and 57B. Here, the connecting member 51 is fixed to the upper end portions of the link 47A and the link 47B to connect the two. Further, the connecting member 51 is actually fixed at its upper surface to the lower surface of the inner ring 42, whereby the link 47 </ b> A and the link 47 </ b> B are attached to the inner ring 42. Further, the fixing members 57A and 57B are fixed to the lower ends of the links 47A and 47B, respectively, and these fixing members 57A and 57B are fixed to the upper surface of the outer ring 48, so that the links 47A and 47B become the outer ring 48. Is attached.

  The connecting member 51 and the fixing members 57A and 57B are made of, for example, titanium or SAS (stainless steel).

  In the present embodiment, the link 47A and the link 47B are integrally provided with elastic hinge portions to be described later at both ends in the longitudinal direction, so the links 47A and 47B including these elastic hinge portions are also included. It is called.

  As shown in FIG. 6A, the link 47A includes a main body portion 53A having a substantially rectangular frame shape, and a piezo element 55A as a drive element disposed in a hollow portion of the main body portion 53A. In the following, for convenience of explanation, the longitudinal direction of the main body 53A is the A-axis direction, one direction (short direction) orthogonal to the A-axis direction is the B-axis direction, and the direction orthogonal to the A-axis and B-axis Is described as the C-axis direction.

The piezo element 55A is composed of a laminated piezoelectric element. For example, PZT (= Pb (Zr · Ti) O ₃ ) having a predetermined thickness and internal electrodes made of a silver / palladium (AgPd) alloy having a predetermined thickness are alternately arranged. Laminated. Here, the thickness of the piezoelectric element (the length in the A-axis direction) is determined by the required driving amount, and is about 10 ⁴ times the driving amount. The required drive amount is determined based on the required drive amount of the mirror necessary for adjusting the projection optical system PO. For example, if the required driving amount is 0.1 μm, the thickness of the piezoelectric element is 1 mm. The material used for the piezo element 55A is not limited to the above, and a ferroelectric material such as BaTiO ₃ , PbTiO ₃ , (NaK) NbO ₃ or the like generally used as a piezo element material can also be used.

  The main body 53A is integrally formed of, for example, titanium or SAS (stainless steel). As shown in FIG. 6B, the main body portion 53A includes a substantially U-shaped guide portion 54, an elastic hinge portion 61B provided on the U-shaped open end (upper end) side of the guide portion 54, An elastic hinge 61A provided at an end (lower end) opposite to the elastic hinge 61B of the guide 54, and a displacement reduction mechanism 59 as a displacement reduction mechanism provided inside the elastic hinge 61B. It consists of four parts.

  As shown in an enlarged view in FIG. 7A, the displacement reduction mechanism unit 59 includes a substantially trapezoidal first portion 59A, a second portion 59B, a first parallel table 59C, and a second parallel table 59D. ing.

  The first portion 59A is connected to the inner surface of the guide portion 54 via the connection portion 59E in the vicinity of the + A side end portion of the + B side surface. The connecting portion 59E functions as a kind of hinge. When a force in the + A direction or the −A direction acts on the first portion 59A, the first portion 59A is shown in FIG. It is designed to rotate clockwise or counterclockwise in A).

  The first portion 59A has the end surface on the −A side connected to the tip surface of the piezo element 55A, and the force in the + A direction or the −A direction is applied to the first portion due to the expansion and contraction of the piezo element 55A. Acts on 59A.

Further, in actuality, a detection target piece 67 shown in FIG. 6A is integrally attached to the surface of the first portion 59A on the + C side, and the sensor is opposed to the detection target piece 67. 163A ₁ is arranged. As the sensor 163A _1, for example, a capacitance sensor (gap sensor) is used. This sensor 163A ₁ is fixed to the guide portion 54 of the main body portion 53A, and detects a change (displacement) in the distance from the detection target piece 67 based on a voltage change caused by a change in capacitance. . Therefore, the output of the sensor 163A ₁ is supplied to the main control device 20 (see FIG. 9), and the main control device 20 calculates the expansion / contraction amount (displacement amount) of the piezo element 55A based on the output of the sensor 163A _1. It can be detected stably and accurately.

  Returning to FIG. 7A, the second portion 59B is connected to the first portion 59A via the connection portion 59F in the vicinity of the + B side end of the −A side surface, and the + A side surface constitutes the elastic hinge portion 61B. Is connected to the remaining portion of the elastic hinge portion 61B via a hinge 162c.

  The first parallel table 59C is connected to the second portion 59B via the connection portion 59G on the + B side surface, and is connected to the inner surface of the guide portion 54 via the connection portion 59H on the -B side surface. The second parallel table 59D is disposed on the + A side of the first parallel table 59C, and is connected to the second portion 59B via the connection portion 59I on the + B side surface thereof and on the −B side surface via the connection portion 59J. The guide portion 54 is connected to the inner surface.

  According to the displacement reduction mechanism 59 configured as described above, when the piezo element 55A expands and generates a force in the + A direction, as shown in FIG. The connecting portion 59E is rotationally driven clockwise with the fulcrum as a fulcrum, and the state shown by the dotted line changes to the state shown by the solid line. Along with this, a force in the + A direction acts also on the second portion 59B via the connection portion 59F, but the second portion 59B is connected to both the first parallel table 59C and the second parallel table 59D. Therefore, the rotation of the second portion 59B caused by the action of the force is suppressed, and as a result, the second portion 59B only slides (translates) in the + A direction.

The parallel movement amount of the second portion 59B at this time is an amount obtained by reducing the expansion amount of the piezo element 55A by the displacement reduction mechanism unit 59 at a predetermined reduction rate γ. Specifically, the reduction ratio gamma, a connecting portion 59E and the distance B axis up to the point of application of the driving force from the piezoelectric element 55A with respect to the first portion 59A a _1, the connecting portion 59E and the connecting portion 59F B If the distance in the axial direction is a ₂ , γ = a ₂ / a ₁ .

  Further, as shown in FIG. 7C, when the piezo element 55A contracts in the -A direction, the displacement of the piezo element 55A is reduced and transmitted to the second portion 59B by the same principle as described above. It has become.

Thus, in the link 47A of the present embodiment, the entire length of the link 47A can be expanded and contracted by the amount by which the expansion / contraction amount of the piezo element 55A is reduced by the predetermined reduction rate γ (γ = a ₂ / a ₁ ). It has become a structure.

  One elastic hinge portion 61A of the elastic hinge portions 61A and 61B is composed of a main body portion 53A located on the −A side of the guide portion 54 as shown in an enlarged view in FIG. Hinge as a first narrow portion extending substantially in the B-axis direction left by forming slits 161a and 161b having a predetermined depth from one side and the other side in the C-axis direction in the vicinity of the −A side end face of 53A The second extending in the C-axis direction is left by forming slits 161c and 161d having a predetermined depth from one side and the other side of the B-axis direction at positions close to the + A side of the portion 162a and the slits 161a and 161b. Hinge portion 162b as a narrow portion. In this case, the hinge portion 162a allows rotation around the B axis of the + A side portion of the main body portion 53A from the hinge portion 162a, and the hinge portion 162b allows the C axis of the + A side portion of the main body portion 53A to be + A side portion. Rotation around is allowed. That is, the elastic hinge portion 61A constitutes a gimbal joint that allows rotation around two rotation axes that are orthogonal to each other.

  The other elastic hinge portion 61B is configured in the same manner as the elastic hinge portion 61A described above. That is, as shown in FIG. 7A, the elastic hinge portion 61B includes a portion of the main body portion 53A located on the + A side of the guide portion 54, and a hinge portion 162c as a first narrow portion perpendicular to each other. And the hinge part 162d as a 2nd narrow part is included. The hinge portion 162c allows rotation around the C axis of the −A side portion of the main body portion 53A relative to the hinge portion 162c, and the hinge portion 162d rotates around the B axis of the −A side portion of the main body portion 53A relative to the hinge portion 162d. Is allowed to rotate. That is, the elastic hinge portion 61B constitutes a gimbal joint that allows rotation around two rotation axes that are orthogonal to each other.

Returning to FIG. 6A, the other link 47B is configured in the same manner as the above-described link 47A, although it is bilaterally symmetric. That is, as shown in FIG. 6A, the link 47B includes a main body portion 53B having a substantially rectangular frame shape, a piezo element 55B as a drive element disposed in a hollow portion of the main body portion 53B, and the piezo element. And a sensor 163B ₁ for detecting the expansion / contraction amount of 55B. Also in this case, the entire length of the link 47B can be expanded and contracted by the amount by which the expansion / contraction amount (displacement amount) of the piezo element 55B is reduced by the predetermined reduction rate γ.

The other links 47C to 47F are also configured in the same manner as the links 47A and 47B, and the expansion / contraction amount (displacement amount) of the piezoelectric element provided in each link is determined by the sensors 163C _{1 to} 163F provided in each link. ₁ (see FIG. 9).

Referring back to FIG. 3A, the lower surface of the mirror M2 is a rotationally symmetric reflecting surface such as a spherical surface or an aspheric surface, and the rotationally symmetric axis (spherical axis or aspherical axis) is the optical axis of the projection optical system PO. A concave mirror whose position is adjusted so as to substantially coincide with AX (see FIGS. 3B and 4). This mirror M2 is held in the split 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. 9) having the configuration can be driven in the direction of six degrees of freedom. The six links constituting the parallel link mechanism 41 ₂ are provided with sensors 163A _{2 to} 163F ₂ (see FIG. 9), and the amount of expansion / contraction of the piezoelectric element in each link is determined by the sensors 163A _{2 to} 163F ₂ , respectively. It has come to be measured.

The mirror M2 is also formed with a reference plane for measuring the X-axis position of the mirror M2 and a reference plane for measuring the Y-axis position, similarly to the mirror M1 described above. Therefore, when the projection optical system PO is incorporated in the exposure apparatus, the position of the mirror M2 is detected by the laser interferometers 63X ₂ and 63Y ₂ (see FIG. 9) provided outside the projection optical system PO. It has become.

As can be understood from 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 its rotational symmetry axis (spherical axis or aspherical axis). The position of the mirror M3 is adjusted to a position that substantially coincides with the optical axis AX. This mirror M3 is held in the split lens 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. It can be driven in the direction of six degrees of freedom by the parallel link mechanism 41 ₃ (see FIG. 9). The six links constituting the parallel link mechanism 41 ₃ are provided with sensors 163A _{3 to} 163F ₃ (see FIG. 9), and the expansion / contraction amounts of the piezo elements in each link are respectively measured by the sensors 163A _{3 to} 163F _3. It has come to be measured.

The mirror M3 also has a reference plane for measuring the X-axis position of the mirror M3 and a reference plane for measuring the Y-axis position, similarly to the mirror M1 described above. Accordingly, when the projection optical system PO is incorporated in the exposure apparatus, the position of the mirror M3 is detected by the laser interferometers 63X ₃ and 63Y ₃ (see FIG. 9) provided outside the projection optical system PO. It has become.

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 rotationally symmetric axis (spherical axis or aspherical axis). The position of the mirror M4 is adjusted to a position that substantially coincides with the optical axis AX. The mirror M4 is held in the split lens 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. 9) having the same configuration as the parallel link mechanism 41 ₁ that constitutes the mechanism can be driven in the direction of 6 degrees of freedom. The six links constituting the parallel link mechanism 41 ₄ are provided with sensors 163A _{4 to} 163F ₄ (see FIG. 9), and the expansion / contraction amounts of the piezo elements in each link are respectively measured by the sensors 163A _{4 to} 163F _4. It has come to be measured.

The mirror M4 is also formed with a reference plane for measuring the X-axis position of the mirror M4 and a reference plane for measuring the Y-axis position, similarly to the mirrors M1 to M3 described above. Accordingly, when the projection optical system PO is incorporated in the exposure apparatus, the position of the mirror M4 is detected by the laser interferometers 63X ₄ and 63Y ₄ (see FIG. 9) provided outside the projection optical system PO. It has become.

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 a part of a rotationally symmetric surface such as a spherical surface or an aspherical surface, and its rotationally symmetric axis (spherical axis or aspherical axis) is substantially the optical axis AX of the projection optical system PO. The position is adjusted to match. 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 the divided 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. 9) having the configuration can be driven in the direction of six degrees of freedom. The six links constituting the parallel link mechanism 41 ₅ are provided with sensors 163A _{5 to} 163F ₅ (see FIG. 9), and the amount of expansion / contraction of the piezoelectric element in each link is determined by the sensors 163A _{5 to} 163F ₅ , respectively. It has come to be measured.

The mirror M5 is also formed with a reference plane for measuring the X-axis position of the mirror M5 and a reference plane for measuring the Y-axis position, similarly to the mirrors M1 to M4 described above. Accordingly, in the state where the projection optical system PO is incorporated in the exposure apparatus, the position of the mirror M5 is detected by the laser interferometers 63X ₅ and 63Y ₅ (see FIG. 9) provided outside the projection optical system PO. It has become.

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 its rotationally symmetric axis (spherical axis or aspherical axis) is substantially the optical axis AX of the projection optical system PO. The position is adjusted to match. In the mirror M5, 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 M5, within the divided tube 152d 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 ₆ (see FIG. 9) having the configuration can be driven in the direction of six degrees of freedom. The _six links constituting the parallel link mechanism 41 ₆ are provided with sensors 163A _{6 to} 163F ₆ (see FIG. 9), and the expansion / contraction amounts of the piezoelectric elements in the links are respectively measured by the sensors 163A _{6 to} 163F _6. It has come to be measured.

The mirror M6 is also formed with a reference plane for measuring the X-axis position of the mirror M6 and a reference plane for measuring the Y-axis position, similarly to the mirrors M1 to M5 described above. Accordingly, when the projection optical system PO is incorporated in the exposure apparatus, the position of the mirror M6 is detected by the laser interferometers 63X ₆ and 63Y ₆ (see FIG. 9) provided outside the projection optical system PO. It has become.

  Here, the operation of the projection optical system PO configured as described above will be described with reference to FIG. Illumination light (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 disposed in the lens barrel 52. The light is reflected almost upward by the bending mirror M constituting a part of the illumination optical system, and enters the reticle R through the opening 52b of the lens barrel 52 at a predetermined incident angle. The illumination 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 illumination 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 illumination light EL reflected by the mirror M5 is reflected by the mirror M6, and is irradiated onto the wafer W through a notch of the mirror M5 as a pattern imaging light beam.

  FIG. 9 shows the main configuration of the control system of the exposure apparatus 10 according to this embodiment. This control system is mainly configured of a main controller 20 that controls the entire apparatus in an integrated manner.

Then, by the main controller 20 (see FIG. 9), the position and posture control of the directions of six degrees of freedom of the mirror through a parallel link mechanism, by taking the parallel link mechanism 41 ₁ and the mirror M1 Typically, Figure A description will be given based on FIGS. Incidentally, in the 10 to 13, six link 47A~47F constituting the inner ring 42 and the parallel link mechanism 41 _1, and the outer ring 48 is shown schematically. The driving of the inner ring 42 means driving of the mirror M1 held on the inner ring 42 via the mirror holding members 44A to 44C. In these drawings, a state (position / posture) based on a state indicated by a dotted line is shown.

  In the main controller 20, for example, the piezo elements constituting the links 47A to 47F are extended, and the total length of each link is changed from the state indicated by the dotted line to the state indicated by the solid line in FIG. The (mirror M1) can be moved in the + Z direction by the distance L1. Of course, in the main controller 20, if it is desired to move the inner ring 42 (mirror M1) in the −Z direction by the distance L1 from this state, the piezo element may be contracted in the opposite manner.

  Further, in the main controller 20, for example, by appropriately controlling expansion and contraction of the piezo elements constituting the links 47A to 47F, each link is changed from a state indicated by a dotted line to a state indicated by a solid line in FIG. The inner ring 42 (mirror M1) can be moved in the horizontal plane (for example, the X-axis direction and the Y-axis direction) by a distance L2.

Further, in the main controller 20, for example, by appropriately controlling expansion and contraction of the piezo elements constituting the links 47A to 47F, each link is changed from a state indicated by a dotted line to a state indicated by a solid line in FIG. The inner ring 42 (mirror M1) can be rotated by a minute angle φ ₁ around an axis passing through the center of gravity (for example, around the X axis or the Y axis), thereby rotating the θx of the inner ring 42 (mirror M1). (Pitching amount) or θy rotation (rolling amount) can be adjusted.

Further, in the main controller 20, for example, by appropriately controlling expansion and contraction of the piezo elements constituting the links 47A to 47F, each link is changed from a state indicated by a dotted line to a state indicated by a solid line in FIG. The inner ring 42 (mirror M1) can be rotated by a minute angle φ ₂ around the Z axis passing through the center of gravity, thereby making it possible to adjust the θz rotation (yawing amount) of the inner ring 42 (mirror M1). .

Thus, the main controller 20, by expansion control the piezoelectric element of each link 47A~47F constituting the parallel link mechanism 41 _1, 6 degrees of freedom of the mirror M1 (X, Y, Z, θx, θy , Θz) can be controlled.

In the present embodiment, similarly to the above, the main control device 20 controls the expansion and contraction of each link of the parallel link mechanisms 41 _{2 to} 41 ₆ , thereby performing the position / posture control of the mirrors M 2 to M 6 in the 6 degrees of freedom direction. Can be done.

  In the exposure apparatus 10 of the present embodiment configured as described above, similarly to an ordinary scanner (scanning stepper), loading of the reticle R (or reticle replacement), loading of the wafer W (or wafer replacement), reticle Preparation work for exposure such as alignment and baseline measurement of the alignment system ALG and wafer alignment (for example, EGA alignment) are performed. However, in reticle alignment, a projection image of a reticle alignment mark (not shown) formed on the reticle R onto the wafer W surface is detected using the aerial image measuring device FM, which is different from a normal scanner.

  After the wafer alignment is completed, step-and-scan exposure is performed using the EUV light EL as exposure illumination light. Since the step-to-shot stepping operation of wafer stage WST and the scanning exposure operation for each shot area on wafer W in this step-and-scan exposure operation are not particularly different from those of a normal scanner, detailed description thereof will be omitted.

  During the scanning exposure and alignment described above, 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 detects the distance from the wafer W surface. Wafer stage WST is controlled so that the distance and parallelism with projection optical system PO are 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.

  In the exposure apparatus 10 of the present embodiment, for example, an imaging characteristic of the projection optical system PO is periodically measured by an operator, and a predetermined result of the projection optical system PO is determined by the main controller 20 based on the measurement result of the imaging characteristic. Image characteristics such as field curvature, astigmatism, coma, spherical aberration, and distortion are adjusted.

  In main controller 20, based on the measurement result of the imaging characteristics, at least one of the six mirrors M1 to M6 such that the aberration out of the appropriate range is within the appropriate range among the above-described aberrations. The drive direction and drive amount of the two mirrors are calculated by a predetermined calculation, and the parallel link mechanism corresponding to the mirror to be driven is controlled. In this case, the position information of the mirror detected by the corresponding laser interferometer is supplied to the main controller 20, and the main controller 20 performs feedback control so that the detected position deviation in the driving direction of the mirror becomes zero. Controls the parallel link mechanism.

  Note that, as a method for measuring the imaging characteristics performed as a precondition for adjusting the imaging characteristics of the projection optical system PO described above, for example, exposure is performed using a measurement mask on which a predetermined measurement pattern is formed, and measurement is performed. A method for calculating imaging characteristics based on a measurement result obtained by measuring a resist image obtained by developing a wafer on which a projected image of a pattern is transferred (baking method), and a wavefront aberration measuring instrument that can be attached to wafer stage WST The measurement of the wavefront aberration of the projection optical system PO using the lens is representatively exemplified. In particular, in the case of the latter wavefront aberration measurement, as disclosed in, for example, the pamphlet of International Publication No. WO 03/075328, a wavefront aberration change table and a Zernike sensitivity table are prepared in advance, and the least squares using these are prepared. By calculating, it is possible to easily calculate the driving direction and target driving amount of each mirror, and it is possible to adjust not only low-order aberrations such as Seidel aberration but also high-order aberrations.

As described above, the parallel link mechanism 41 ₁ constituting the mirror holding device 92 according to this embodiment, the inner ring 42 holding mechanism for holding the mirror M1 (mirror holding member 44A-44C) constitute the end effector Provided with a link mechanism 46 that drives the inner ring 42 in the direction of six degrees of freedom with respect to the outer ring 48 that constitutes the base, and each of the links 47A to 47F that constitute the link mechanism 46 includes A retractable drive element (piezo element), and a displacement reduction mechanism 59 connected in series to one end of the drive element in the extension / contraction direction and reducing the extension / contraction displacement of the drive element and transmitting it to the inner ring 42. ing. The mirror holding device that holds the other mirrors M <b> 2 to M <b> 6 so as to be movable in directions of 6 degrees of freedom is configured similarly to the mirror holding device 92.

For this reason, in the mirror holding device of this embodiment, each link and thus the link mechanism can be set to be small and light, and the expansion and contraction of the drive element is reduced by the displacement reduction mechanism and transmitted to the inner ring 42. As a result, the mirror is driven integrally with the inner ring 42. Therefore, the mirror can be driven with high accuracy and the parallel link mechanisms 41 _{1 to} 41 ₆ can be arranged without any trouble even in a space where the mirror (optical member) and the light beam are densely packed as shown in FIG. It is possible.

  Further, according to the present embodiment, all of the plurality of mirrors M1 to M6 constituting the projection optical system PO are held by the above-described mirror holding device that can finely drive the mirrors with high accuracy. Thus, it is possible to perform fine adjustment of the mirror in the projection optical system PO, and consequently, high-precision adjustment of the optical characteristics (for example, imaging characteristics) of the projection optical system PO.

  Further, according to the exposure apparatus 10 of the present embodiment, the pattern formed on the reticle R through the projection optical system PO is adjusted to the wafer while the imaging characteristics (optical characteristics) of the projection optical system PO are adjusted with high accuracy. It can be transferred onto W with high accuracy. Further, in the exposure apparatus 10, the EUV light EL having an extremely short wavelength is used as the exposure light, and the pattern of the reticle R is transferred onto the wafer W via the reflective projection optical system PO having no chromatic aberration. This fine pattern can be transferred to each shot area on the wafer W with high accuracy. Specifically, a fine pattern with a minimum line width of about 70 nm can be transferred with high accuracy.

  In the above embodiment, the elastic hinge portions 61A and 61B are formed in the vicinity of the connecting portion between the inner ring 42 and the link and in the vicinity of the connecting portion between the outer ring and the link. However, the present invention is not limited to this, and other gimbal joints that allow rotation around two rotation axes orthogonal to each other in a plane orthogonal to the longitudinal direction of the link may be provided. Of course, a ball joint or the like may be provided instead of the gimbal joint.

  In the above-described embodiment, the case where the displacement reduction mechanism portion is integrally formed with the guide portion of the link has been described. However, the displacement reduction mechanism may be provided separately from the guide portion, and both may be integrated.

  In the above embodiment, the case where a piezo element is employed as the drive element has been described. However, the present invention is not limited to this, and any drive element that can expand and contract its entire length in the longitudinal direction will be described. Various driving elements can be employed.

  Moreover, although the case where the electrostatic capacitance sensor was employ | adopted as a sensor which detects the expansion / contraction amount of a piezoelectric element was demonstrated in the said embodiment, it is not restricted to this, The drive element of other sensors (for example, linear encoder etc.) is demonstrated. Various sensors can be employed as long as they can detect the amount of expansion and contraction. The sensor for detecting the amount of expansion / contraction of the piezo element is not limited to being provided directly on the link, but a sensor may be provided outside. Further, the present invention is not limited to detecting the amount of expansion / contraction of the piezo element, and a sensor that detects the actual amount of expansion / contraction of the link may be employed.

  In the above embodiment, each of the six mirrors has been described as being driven in the direction of six degrees of freedom. However, it is sufficient that at least one mirror can be driven. The at least one mirror may be drivable in a two-degree-of-freedom direction, a three-degree-of-freedom direction, a four-degree-of-freedom direction, or a five-degree-of-freedom direction excluding rotation about the Z axis.

  In the above embodiment, the case where all the mirrors in the projection optical system PO are held by the optical member holding device of the present invention has been described. However, one or more mirrors in the projection optical system PO are the optical members of the present invention. Even in this case, the mirror can be finely driven with high accuracy. Therefore, fine adjustment of the mirror in the projection optical PO, and consequently the projection optical system PO. Can be adjusted with high accuracy.

  In the above embodiment, a mechanism using the lever principle is employed as the displacement reduction mechanism. However, the present invention is not limited to this, and other mechanisms may be employed.

  In the above embodiment, the case where the optical member is a mirror has been described. However, the present invention is not limited to this, and the optical member may be a lens.

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 optical unit 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 unit of the present invention is used. It may be employed as an illumination optical 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.

  As described above, the optical member holding device of the present invention is suitable for holding an optical member so as to be movable in a predetermined direction. The optical unit of the present invention is suitable for use in a projection optical system of an exposure apparatus. The exposure apparatus of the present invention is suitable for transferring a mask pattern onto a photosensitive object.

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 division | segmentation lens barrel 152c. 6A is an enlarged perspective view showing the links 47A and 47B, and FIG. 6B is a perspective view showing only the main body portion extracted from FIG. 6A. FIG. 7A is an enlarged view of the displacement reduction mechanism, and FIG. 7B is a view showing the state of the displacement reduction mechanism when the piezo element 55A extends in the + A direction. FIG. 7C is a diagram illustrating the state of the displacement reduction mechanism when the piezo element 55A contracts in the -A direction. It is a perspective view which expands and shows an elastic hinge part. It is a block diagram which shows the control system of one Embodiment of this invention. It is FIG. (1) for demonstrating the drive of a 6 degrees-of-freedom direction of a mirror. It is FIG. (2) for demonstrating the drive of a 6 degrees-of-freedom direction of a mirror. It is FIG. (3) for demonstrating the drive of a 6 degrees-of-freedom direction of a mirror. It is FIG. (4) for demonstrating the drive of a 6 degrees-of-freedom direction of a mirror.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus, 41 ₁ ... Parallel link mechanism (parallel link mechanism), 42 ... Inner ring (end effector), 44A-44C ... Holding member (mirror holding member), 47A-47F ... Link, 48 ... Outer ring (base) ), 49 ... Displacement reduction mechanism (displacement reduction mechanism), 55A ... Piezo element (drive element), 61A, 61B ... Elastic hinge part (gimbal joint), 92 ... Mirror holding device (optical member holding device), 162a, 162c ... hinge part (first narrow part), 162b, 162d ... hinge part (second narrow part), 163A _{1 to} 163F ₆ ... sensor, M1 to M6 ... mirror (optical member), PO ... projection optics System (optical unit), R ... reticle (mask), W ... wafer (object).

Claims (13)

An optical member holding device that holds an optical member so as to be movable in a predetermined direction,
A holding mechanism for holding the optical member;
A parallel link mechanism, wherein the holding mechanism is provided on the end effector, and the link mechanism has a link mechanism that drives the end effector in a direction of multiple degrees of freedom with respect to the base;
Each link constituting the link mechanism is connected in series to a telescopic drive element and one end of the drive element in the expansion / contraction direction, and a displacement reduction mechanism that reduces the expansion / contraction displacement of the drive element and transmits it to the end effector. And an optical member holding device.   The link between the end effector and the base of each link is a gimbal joint that allows rotation about two rotation axes that are orthogonal to each other in a plane orthogonal to the expansion / contraction direction of the drive element constituting the link. The optical member holding device according to claim 1, wherein each of the optical member holding devices is provided.   Each gimbal joint is provided at a connection portion of the link with the end effector or the base, and a first narrow portion and a first portion perpendicular to each other at different positions in the expansion / contraction direction of the drive element constituting the link. The optical member holding device according to claim 2, wherein the two narrow portions are formed by members formed respectively.   The optical member holding device according to claim 3, wherein the displacement reduction mechanism is integrally formed with the member.   The optical member holding apparatus according to claim 1, wherein the driving element is a piezo element.   The optical member holding device according to claim 1, further comprising a sensor that detects an amount of expansion / contraction of the driving element.   The optical member holding device according to claim 6, wherein the sensor is a capacitance sensor.   The optical member holding device according to any one of claims 1 to 7, wherein the parallel link mechanism drives the optical member in a direction of six degrees of freedom.   The optical member holding device according to claim 1, wherein the displacement reduction mechanism is a mechanism using a lever principle. In an optical unit comprising a plurality of optical members,
An optical unit, wherein at least one of the plurality of optical members is held by the optical member holding device according to claim 1.   The optical unit according to claim 10, wherein all of the plurality of optical members are held by the optical member holding device according to claim 1. An exposure apparatus for transferring a pattern formed on a mask onto an object via a projection optical system,
An exposure apparatus comprising the optical unit according to claim 10 or 11 as the projection optical system. A reflective mask is used as the mask,
All the optical members constituting the optical unit are mirrors, and a reflective film of each mirror is provided with a multilayer film for reflecting extreme ultraviolet light on the surface thereof. The exposure apparatus described.

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