JP2011096931A - Optical system, exposure apparatus and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system capable of suitably maintaining a wavefront aberration of an optical element arranged in a lens barrel, an exposure apparatus and a method of manufacturing a device. <P>SOLUTION: A projection optical system 16 includes a lens barrel 40 made of a low-thermal-expansion material, mirrors 28, 33 disposed in the lens barrel 40, a mirror holding apparatus which holds the mirrors 28, 33 and includes an actuator for driving the mirrors 28, 33 to move to the lens barrel 40, a measuring apparatus 60 which measures positions of the mirrors 28, 33 relatively to the lens barrel 40, and a controller which controls the mirror holding apparatus on the basis of measurement results of the measuring apparatus 60. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical system including a lens barrel in which an optical element is accommodated, an exposure apparatus including the optical system, and a device manufacturing method using the exposure apparatus.

  In general, in a lithography process for manufacturing a microdevice such as a semiconductor integrated circuit, an exposure apparatus that forms a pattern on a substrate such as a wafer or a glass plate coated with a photosensitive material is used. A projection optical system mounted on such an exposure apparatus includes a lens barrel and a plurality of optical elements (for example, reflection mirrors) accommodated in the lens barrel, and each optical element is optical with respect to the lens barrel. Each element is supported by a lens barrel via an optical element holding device capable of adjusting the position of the element (see Patent Document 1).

  In the exposure apparatus, the wavefront aberration of the projection optical system is adjusted by driving the optical element holding devices to adjust the positions of the optical elements. By executing the exposure process in a state where the wavefront aberration of the projection optical system is appropriately adjusted in this way, a pattern having an appropriate size and shape is formed on the substrate disposed on the image plane side of the projection optical system. It was.

JP 2007-201342 A

  By the way, each optical element constituting the projection optical system absorbs a part of the exposure light incident thereon, and raises the temperature of each optical element itself. In particular, in an exposure apparatus that uses EUV (Extreme Ultraviolet) light as exposure light, the amount of heat absorbed by the optical element is greater than in an exposure apparatus that uses light of other wavelengths as exposure light. The heat absorbed by each optical element is transmitted to the lens barrel via the optical element holding device that holds the optical element, or is transmitted to the lens barrel by radiant heat from the optical element. Then, since such heat is transmitted to the entire lens barrel, the lens barrel is thermally expanded, that is, similarly expanded. For this reason, the positional relationship between the optical elements constituting the projection optical system changes, or the optical element arranged at a position shifted from the central axis of the lens barrel is decentered, and the wavefront aberration of the projection optical system is subject to exposure processing. There was a risk of change.

  Further, in order to adjust the change of the wavefront aberration of the projection optical system generated during the exposure process, a method of periodically measuring the wavefront aberration and adjusting the position and shape of each optical element based on the measurement result can be considered. . However, in order to measure the wavefront aberration of the projection optical system, it is necessary to temporarily stop the exposure process, which causes a problem that the efficiency of the lithography process is lowered.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an optical system, an exposure apparatus, and a device manufacturing method that can favorably maintain the wavefront aberration of an optical element disposed in a lens barrel. There is to do.

In order to solve the above-described problems, the present invention employs the following configuration corresponding to FIGS. 1 to 12 shown in the embodiment.
The optical system of the present invention includes a lens barrel (40) made of a low thermal expansion material, optical elements (28, 29, 30, 31, 32, 33) disposed in the lens barrel (40), Drives to hold the optical element (28, 29, 30, 31, 32, 33) and move the optical element (28, 29, 30, 31, 32, 33) relative to the lens barrel (40). Optical element holding device (43A, 43B, 43C, 43D, 43E, 43F) having a drive unit (55) for the above, and the optical elements (28, 29, 30, 31, 32, 33) for the lens barrel (40) And a control unit (131) for controlling the optical element holding device (43A, 43B, 43C, 43D, 43E, 43F) based on a measurement result by the measurement device (60). The gist is to provide .

  According to the said structure, since a lens-barrel (40) is comprised with a low thermal expansion material, it is hard to thermally expand. Therefore, the displacement of the optical elements (28, 29, 30, 31, 32, 33) supported by the lens barrel (40) via the optical element holding devices (43A, 43B, 43C, 43D, 43E, 43F) is suppressed. Is done. The optical system of the present invention is provided with a measuring device (60) for measuring the position of the optical element (28, 29, 30, 31, 32, 33) with respect to the lens barrel (40). Therefore, the position of the optical element (28, 29, 30, 31, 32, 33) with respect to the lens barrel (40) can be measured even during the exposure process.

  In order to explain the present invention in an easy-to-understand manner, it has been described in association with the reference numerals of the drawings showing the embodiments, but it goes without saying that the present invention is not limited to the embodiments.

  According to the present invention, it is possible to favorably maintain the wavefront aberration of the optical element disposed in the lens barrel.

1 is a schematic block diagram that shows an exposure apparatus in the present embodiment. FIG. 3 is a schematic side view showing the inside of a lens barrel of the projection optical system. The perspective view which shows a mirror holding device typically. FIG. 3 is a side sectional view schematically showing an axial interferometer. FIG. 3 is a side sectional view schematically showing a radial interferometer. The top view which shows typically the radial direction interferometer for 4th mirrors. The sectional side view which shows typically the radial direction interferometer for 4th mirrors. The cross-sectional view which shows typically the diameter measuring interferometer. FIG. 3 is a block diagram illustrating an electrical configuration. (A) is a sectional side view schematically showing an axial interferometer in another embodiment, and (b) is a plan sectional view schematically showing a main part of the axial interferometer. The flowchart of the manufacture example of a device. The detailed flowchart regarding the board | substrate process in the case of a semiconductor device.

  Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. In this embodiment, the direction parallel to the optical axis of the projection optical system is the Z-axis direction, and the scanning direction of the reticle R and wafer W during scanning exposure in a plane perpendicular to the Z-axis direction is the Y-axis direction. The non-scanning direction orthogonal to the scanning direction will be described as the X-axis direction. The rotation directions around the X, Y, and Z axes are also referred to as the θx direction, the θy direction, and the θz direction.

  As shown in FIG. 1, an exposure apparatus 11 according to this embodiment uses extreme ultraviolet light, ie, EUV (Extreme Ultraviolet) light, which is a soft X-ray region having a wavelength of about 100 nm or less, emitted from a light source device 12 as exposure light. It is an EUV exposure apparatus used as an EL. Such an exposure apparatus 11 includes a chamber 13 (a portion surrounded by a two-dot chain line in FIG. 1) whose inside is set to a vacuum atmosphere lower in pressure than the atmosphere. In this chamber 13, an illumination optical system 14 that illuminates a reflective reticle R on which a predetermined pattern is formed with exposure light EL supplied from the light source device 12 into the chamber 13, and pattern formation in which a pattern is formed A reticle stage 15 that holds the reticle R is provided so that the surface Ra is positioned on the −Z direction side (lower side in FIG. 1). Further, in the chamber 13, a projection optical system 16 that irradiates a wafer W coated with a photosensitive material such as a resist by exposure light EL through the reticle R, and an exposure surface (a wafer surface coated with the photosensitive material). ) A wafer stage 17 for holding the wafer W is provided so that Wa is positioned on the + Z direction side (upper side in FIG. 1).

  The light source device 12 is a device that outputs EUV light having a wavelength of 5 to 20 nm as exposure light EL, and includes a laser excitation plasma light source (not shown). In this laser-excited plasma light source, plasma is generated by irradiating a high-density EUV light generating substance (target) with a high-power laser such as a YAG laser or excimer laser using semiconductor laser excitation, and EUV light is emitted from the plasma. Is emitted as exposure light EL. Such exposure light EL is condensed by a condensing optical system (not shown) and output into the chamber 13.

  The illumination optical system 14 includes a housing 18 (a portion surrounded by a one-dot chain line in FIG. 1) in which the inside is set to a vacuum atmosphere, similarly to the inside of the chamber 13. A collimating mirror 19 for condensing the exposure light EL output from the light source device 12 is provided in the housing 18, and the collimating mirror 19 converts the incident exposure light EL into a substantially parallel shape. Then, the light is emitted toward a fly-eye optical system 20 (a part surrounded by a broken line in FIG. 1) which is a kind of optical integrator. The fly-eye optical system 20 includes a pair of fly-eye mirrors 21 and 22, and an incident-side fly-eye mirror 21 arranged on the incident side of the fly-eye mirrors 21 and 22 forms a pattern of the reticle R. It is disposed at a position optically conjugate with the surface Ra. The exposure light EL reflected by the incident-side fly-eye mirror 21 is incident on the exit-side fly-eye mirror 22 arranged on the exit side.

  Further, the illumination optical system 14 is provided with a condenser mirror 23 that emits the exposure light EL emitted from the exit-side fly-eye mirror 22 to the outside of the housing 18. Then, the exposure light EL emitted from the condenser mirror 23 is guided to the reticle R held on the reticle stage 15 by a reflection mirror 24 for folding, which is installed in a lens barrel 40 described later.

  The reticle stage 15 is disposed on the object plane side of the projection optical system 16 and includes a first electrostatic chuck holding device 25 for electrostatic chucking of the reticle R. The first electrostatic attraction / holding device 25 includes a base body 26 made of a dielectric material and having an attracting surface 26a, and a plurality of electrode portions (not shown) disposed in the base body 26. When a voltage is applied to each electrode unit from a voltage application unit (not shown), the reticle R is electrostatically adsorbed on the adsorption surface 26 a by the Coulomb force generated from the base body 26.

  The reticle stage 15 is movable in the Y-axis direction (left and right direction in FIG. 1) by driving a reticle stage drive unit (not shown). In other words, the reticle stage drive unit moves the reticle R held by the first electrostatic attraction holding device 25 with a predetermined stroke in the Y-axis direction. The reticle stage drive unit can also move the reticle R in the X-axis direction (the direction orthogonal to the paper surface in FIG. 1), the Z-axis direction, and the θz direction. When the pattern formation surface Ra of the reticle R is illuminated with the exposure light EL, a substantially arcuate illumination region extending in the X-axis direction is formed on a part of the pattern formation surface Ra.

  The projection optical system 16 is a reflection optical system having a numerical aperture of 0.1, for example, and having reflection type mirrors 28, 29, 30, 31, 32, and 33 which are a kind of optical elements. In the present embodiment, a projection optical system having a projection magnification of ¼ is used. Then, the exposure light EL reflected by the reticle R is guided to the wafer W via the projection optical system 16. The specific configuration of the projection optical system 16 will be described in detail later.

  Reflective layers that reflect the exposure light EL are formed on the reflective surfaces of the mirrors 19, 21 to 24, and 28 to 33 included in the illumination optical system 14 and the projection optical system 16. Each of these reflective layers has a multilayer film in which molybdenum (Mo) and silicon (Si) are alternately stacked.

  The wafer stage 17 includes a second electrostatic chuck holding device 34 for electrostatic chucking of the wafer W, and the second electrostatic chuck holding device 34 is made of a dielectric material and has a chucking surface 35a. And a plurality of electrode portions (not shown) disposed in the base body 35. When a voltage is applied to each electrode unit from a voltage application unit (not shown), the wafer W is electrostatically adsorbed on the adsorption surface 35 a by the Coulomb force generated from the base body 35. Further, the wafer stage 17 includes a wafer holder (not shown) that holds the second electrostatic chuck holding device 34, a position of the wafer holder in the Z-axis direction (vertical direction in FIG. 1), and inclination angles around the X axis and the Y axis. A Z leveling mechanism (not shown) for adjusting the angle is incorporated.

  The wafer stage 17 can be moved in the Y-axis direction by a wafer stage driving unit (not shown). That is, the wafer stage drive unit moves the wafer W held by the second electrostatic chuck holding device 34 in the Y-axis direction with a predetermined stroke. In addition, the wafer stage drive unit can move the wafer W held by the second electrostatic chuck holding device 34 in the X-axis direction with a predetermined stroke, and can also move the wafer W in the Z-axis direction. It is comprised so that it may become.

  When a pattern of the reticle R is formed on one shot area of the wafer W, the reticle R is driven in the Y-axis direction (by the reticle stage driving unit in a state where the illumination area is formed on the reticle R by the illumination optical system 14 ( For example, the projection optical system 16 is reduced with respect to the movement of the reticle R along the Y-axis direction by driving the wafer stage driving unit while moving the wafer W from the + Y direction side to the −Y direction side). It is moved in synchronization with the Y-axis direction (for example, from the −Y direction side to the + Y direction side) at a speed ratio according to the magnification. When the pattern formation on one shot area is completed, the pattern formation on the other shot areas of the wafer W is continuously performed.

Next, the projection optical system 16 of the present embodiment will be described in detail based on FIG. 1 or FIG.
As shown in FIGS. 1 and 2, the projection optical system 16 includes a lens barrel 40 (indicated by a one-dot chain line in FIG. 1) and a plurality of sheets (indicated by a one-dot chain line in FIG. In this embodiment, six reflection mirrors 28 to 33 are provided. The exposure light EL guided from the reticle R side, which is the object plane side, is in the order of the first mirror 28, the second mirror 29, the third mirror 30, the fourth mirror 31, the fifth mirror 32, and the sixth mirror 33. The light is reflected and guided to the wafer W held on the wafer stage 17.

  The positions of the mirrors 28 to 33 are adjusted so that their reflecting surfaces have a predetermined positional relationship with respect to the central axis AX of the lens barrel 40 (that is, the optical axis of the projection optical system 16). Further, each of the mirrors 28 to 33 is processed so as not to block the exposure light EL. The fourth mirror 31 is disposed at a position where the central axis 31a is separated from the central axis AX by a predetermined distance, and the other mirrors 28 to 30, 32, and 33 are disposed in the cylindrical portion of the lens barrel 40. Contained.

The lens barrel 40 includes substantially cylindrical divided lens barrels 40A, 40B, 40C, 40D, 40E, and 40F, and a ring-shaped flange 41 supported by the chamber 13 via a support device (not shown). Each of the divided lens barrels 40A to 40F and the flange 41 are respectively made of a low thermal expansion material having a linear thermal expansion coefficient of 1.0 × 10 ⁻⁶ / ° C. or less. As an example of such a low thermal expansion material, low thermal expansion glass (specifically, Shotod's Zerodure (trade name), etc.) having a thermal expansion coefficient of 0.02 × 10 ⁻⁶ / ° C. can be mentioned.

  Moreover, each division | segmentation lens barrel 40A-40F respond | corresponds to each mirror 28-33 separately, and each division | segmentation lens barrel 40A-40F and the flange 41 are each arrange | positioned along the Z-axis direction. That is, the split lens barrel 40A is arranged on the −Z direction side (lower side in FIG. 2 and on the wafer W side) of the flange 41, and on the + Z direction side (upper side in FIG. 2 and the reticle R). Side) is fixed to the flange 41. Further, the divided lens barrel 40A supports the first mirror 28 via the first mirror holding device 43A.

  The divided lens barrel 40B is disposed on the most in the + Z direction side among the divided lens barrels 40A to 40F, and supports the second mirror 29 via the second mirror holding device 43B. Further, the opening on the + Z direction side of the dividing lens barrel 40B is closed by a bottomed cylindrical dividing lens barrel 40G, and an opening (not shown) that allows passage of the exposure light EL is formed in the dividing lens barrel 40G. Has been.

  The split lens barrel 40 </ b> C is disposed on the + Z direction side of the flange 41, and the −Z direction side portion is fixed to the flange 41. The split lens barrel 40C supports the third mirror 30 via the third mirror holding device 43C.

  The divided lens barrel 40D is disposed between the divided lens barrel 40B and the divided lens barrel 40C in the Z-axis direction, and a portion on the −Z direction side is fixed to the divided lens barrel 40C and a portion on the + Z direction side Is fixed to the split barrel 40B. Further, the split lens barrel 40D has a cut-out side surface in the + Y direction (left side surface in FIG. 2). The split lens barrel 40D supports the fourth mirror 31 via the fourth mirror holding device 43D so that at least a part of the fourth mirror 31 is located outside the split lens barrel 40D. The split lens barrel 40D supports the reflecting mirror 24 that constitutes a part of the illumination optical system 14 via a holding device (not shown).

  The divided lens barrel 40E is disposed on the most −Z direction side among the divided lens barrels 40A to 40F, and supports the fifth mirror 32 via the fifth mirror holding device 43E. Further, the opening on the −Z direction side of the split lens barrel 40E is closed by a bottomed cylindrical split lens barrel 40H, through which the exposure light EL emitted to the wafer W side passes. An opening (not shown) that permits the above is formed.

  The divided lens barrel 40F is disposed between the divided lens barrel 40A and the divided lens barrel 40E in the Z-axis direction, and a portion on the −Z direction side is fixed to the divided lens barrel 40E and a portion on the + Z direction side Is fixed to the split barrel 40A. Further, the divided lens barrel 40F supports the sixth mirror 33 via the sixth mirror holding device 43F.

  Further, the projection optical system 16 of the present embodiment is provided with a measuring device 60 (see FIGS. 4 to 8) for measuring the positions of the mirrors 28 to 33 with respect to the lens barrel 40. The configuration of the measuring device 60 will be described later.

  Next, of the mirror holding devices 43A to 43F that hold the mirrors 28 to 33, the first mirror holding device 43A for the first mirror 28 will be described with reference to FIGS. Since the other mirror holding devices 43B to 43F have substantially the same configuration as the first mirror holding device 43A, their detailed description is omitted. In FIGS. 2 and 3, illustration of each member constituting the measuring device 60 is omitted for the sake of easy understanding of the description.

  As shown in FIGS. 2 and 3, on the −Z direction side of the divided lens barrel 40 </ b> A, a support portion (flange portion) 44 protruding inside the divided lens barrel 40 </ b> A is formed. The first mirror holding device 43A is supported via a plurality of (three in this embodiment) position coarse adjustment mechanisms 45 arranged at equal intervals along the circumferential direction around the central axis AX of the lens barrel 40. Yes. The first mirror holding device 43A includes an annular outer ring 46 supported by the support portion 44 of the split lens barrel 40A via each position coarse adjustment mechanism 45, and the outer ring 46 is substantially parallel to the XY plane. It is arranged in the state. Further, the first mirror holding device 43A is provided with a parallel link mechanism 47 disposed on the outer ring 46 and an annular inner ring 48 supported by the parallel link mechanism 47. 48 supports the first mirror 28 via a plurality of (three in this embodiment) holding mechanisms 49. As the parallel link mechanism 47 is driven, the position of the inner ring 48 is displaced, so that at least one of the position and posture of the first mirror 28 relative to the outer ring 46 is adjusted.

  The parallel link mechanism 47 is driven to move the inner ring 48 with respect to the outer ring 46 in directions of six degrees of freedom of the X axis direction, the Y axis direction, the Z axis direction, the θx direction, the θy direction, and the θz direction. That is, the parallel link mechanism 47 includes a plurality (three in this embodiment) of link mechanisms 51 having two links 50, and the link mechanisms 51 are arranged at equal intervals in the circumferential direction.

  Each link 50 is formed so that both ends in the longitudinal direction form a spherical pair on the outer ring 46 and the inner ring 48. Specifically, each link 50 has a first shaft member 52 and a second shaft member 53 connected to or coupled to the first shaft member 52. One end (lower end) of each first shaft member 52 is attached to the outer ring 46 via a ball joint 54, and the other end (upper end) of each second shaft member 53 is a ball joint (not shown) on the inner ring 48. Are attached through each. Then, at least one of the first shaft member 52 and the second shaft member 53 is changed in the length of the link 50, that is, the distance between one end of the first shaft member 52 and the other end of the second shaft member 53. Actuators 55 (see FIG. 9) that are driven accordingly are provided. An example of the actuator 55 is a piezoelectric element that is driven to extend and contract in the longitudinal direction of the link 50. Each link 50 expands and contracts when the actuator 55 is driven based on the control device 130 described later.

  Each holding mechanism 49 is disposed at the same circumferential position as each link mechanism 51 and on the surface (the upper surface in FIG. 3) of the inner ring 48 on the + Z direction side. Each of these holding mechanisms 49 is formed in a substantially inverted U shape that closes on the + Z direction side and opens on the −Z direction side. That is, each holding mechanism 49 has a pair of extending portions 49a extending in the Z-axis direction, and a connecting portion 49b that connects the ends of the extending portions 49a on the + Z direction side.

  Next, the measuring device 60 of the present embodiment will be described with reference to FIGS. 4 to 8, illustration of a mirror holding device that holds the mirror is omitted for the sake of convenience in understanding the description.

  FIG. 4 shows a portion for measuring the position of the sixth mirror 33 in the Z-axis direction in the measuring device 60. That is, an interferometer housing space 61A that opens on the −Z direction side and closes on the + Z direction side is formed inside the flange 41 in the radial direction. Further, the side wall of the lens barrel 40 has a through-hole 61B extending along a first direction (in this embodiment, the Z-axis direction) substantially parallel to the central axis AX of the lens barrel 40, and a sixth mirror 33 in the Z-axis direction. And a recess 61C located at the same position. The opening end on the + Z direction side (upper side in FIG. 4) of the through hole 61B communicates with the interferometer housing space 61A, and the opening end on the −Z direction side (lower side in FIG. 4) of the through hole 61B is a recess. It communicates with 61C. An axial interferometer 61 that measures the position of the sixth mirror 33 in the Z-axis direction with respect to the flange 41 in the measuring device 60 is provided in the interferometer housing space 61A and the recess 61C.

  The axial interferometer 61 includes an axial light emitting section 62 that is fixed to the + Z direction side portion 41b of the flange 41 in the interferometer housing space 61A and outputs the measurement light SL1 along the Z-axis direction. The axial light emitting section 62 is disposed at substantially the same position as the through hole 61B in the radial direction and the circumferential direction. Further, in the interferometer housing space 61A, the measurement light SL1 that is supported by the flange 41 via a support unit (not shown) and output from the axial light emitting unit 62 is incident on the −Z direction side of the axial interferometer 61. A first beam splitter 64 having an optical surface 63 is provided. The first beam splitter 64 is arranged such that the incident angle when the measurement light SL1 output from the axial light emitting unit 62 is incident on the optical surface 63 is 45 °. Then, most of the measurement light SL1 incident on the first beam splitter 64 enters the through hole 61B formed in the side wall of the lens barrel 40, and proceeds in the through hole 61B toward the −Z direction side. .

  In addition, an axial observation unit 66 supported by the flange 41 and having an image sensor such as a CCD is provided on the radially outer side (right side in FIG. 4) of the first beam splitter 64 in the interferometer housing space 61A. ing. And the observation result by this axial direction observation part 66 is output to the control apparatus 130 mentioned later.

  A second beam splitter 67 is provided in the recess 61C so as to close the through hole 61B. The second beam splitter 67 is provided with the measurement light SL1 emitted from the through hole 61B into the recess 61C. Is provided with a reference surface 68 that reflects a part of the reference beam to the first beam splitter 64 side. The reference surface 68 is a plane substantially orthogonal to the optical path of the measurement light SL1 extending in the Z-axis direction, and the height difference between the concave portion and the convex portion is 1/20 or less of the wavelength of the measurement light SL1. It is processed (for example, polished). Then, most of the measurement light SL1 reflected by the reference surface 68 travels in the + Z direction side through the through hole 61B on the side wall of the lens barrel 40, and then is axially viewed by the optical surface 63 of the first beam splitter 64. Reflected on the 66 side.

  The recess 61 </ b> C accommodates the distal end of a substantially rectangular parallelepiped measuring member 69 whose base end is fixed to the sixth mirror 33. A test surface 70 facing the reference surface 68 at the tip of the measurement member 69 is a plane substantially parallel to the reference surface 68. A reflection coat for total reflection is formed on the test surface 70 so that the measurement light SL1 transmitted through the reference surface 68 is returned to the reference surface 68 side. Most of the measurement light SL1 reflected by the test surface 70 travels in the through hole 61B on the side wall of the lens barrel 40 via the reference surface 68 in the + Z direction side, and then the optical surface of the first beam splitter 64. 63 is reflected to the axial direction observation unit 66 side. At this time, the measurement light SL1 reflected by the test surface 70 and the measurement light SL1 reflected by the reference surface 68 interfere with each other. That is, the axial direction observation unit 66 can measure the interference fringes according to the difference (that is, the interval H1) between the reference surface 68 and the test surface 70 in the Z-axis direction.

  Note that the measuring apparatus 60 of the present embodiment is provided with an axial interferometer for measuring the position in the Z-axis direction with reference to the reference portion of the mirrors 28 to 32 other than the sixth mirror 33. . Since these axial interferometers have substantially the same configuration as the axial interferometer 61 for the sixth mirror 33, the description of these configurations is omitted.

  FIG. 5 shows a portion for measuring the position in the radial direction around the central axis AX of the sixth mirror 33 in the measuring device 60. That is, on the inner side in the radial direction of the flange 41, an interferometer housing space 75A that is open on the −Z direction side and closed on the + Z direction side is formed, and the interferometer housing space 75A is an axial interferometer 61. And are arranged at different positions in the circumferential direction. The side wall of the lens barrel 40 has a through hole 75B extending along a first direction (in the present embodiment, the Z-axis direction) substantially parallel to the central axis AX of the lens barrel 40, and a sixth mirror 33 in the Z-axis direction. And a recess 75C located at the same position. The opening end on the + Z direction side (upper side in FIG. 5) of the through hole 75B communicates with the interferometer housing space 75A, and the opening end on the −Z direction side (lower side in FIG. 5) of the through hole 75B is a recess. It communicates with 75C. In the interferometer housing space 75A and the concave portion 75C, radial interference for measuring the position in the radial direction around the central axis AX of the sixth mirror 33 with respect to the inner surface 40a of the barrel 40 in the measuring device 60. A total of 75 is provided.

  The radial interferometer 75 is provided with a radial light emitting portion 76 that is fixed to the + Z direction side portion 41b of the flange 41 in the interferometer housing space 75A and outputs the measurement light SL2 along the Z-axis direction. The radial light emitting portion 76 is disposed at substantially the same position as the through hole 75B in the radial direction and the circumferential direction. Further, in the interferometer housing space 75A, a first beam splitter 78 having an optical surface 77 that is supported by the flange 41 via a support portion (not shown) and on which the measurement light SL2 output from the radial light emitting portion 76 is incident. Is provided. The first beam splitter 78 is arranged so that the incident angle when the measurement light SL2 output from the radial light emitting unit 76 enters the optical surface 77 is 45 °. Then, most of the measurement light SL2 incident on the first beam splitter 78 enters the through hole 75B formed in the side wall of the lens barrel 40, and proceeds in the through hole 75B toward the −Z direction side. .

  Further, in the interferometer accommodating space 61A, a radial direction observation unit 80 supported by the flange 41 and having an image pickup device such as a CCD is provided on the radial direction outer side (right side in FIG. 4) of the first beam splitter 64. ing. And the observation result by this radial direction observation part 80 is output to the control apparatus 130 mentioned later.

  The bottom surface of the recess 75C functions as a reflecting surface 82 that reflects the measurement light SL2 traveling in the −Z direction side through the through hole 75B on the side wall of the lens barrel 40 toward the radially inner side (that is, the sixth mirror 33). To do. That is, the reflection surface 82 is formed so that the incident angle of the measurement light SL2 that has traveled in the −Z direction side through the side wall of the lens barrel 40 is approximately 45 °. A reflective coat for totally reflecting incident light may be formed on the reflective surface 82.

  Further, on the inner side surface of the barrel 40, there is provided a plate-like closing member 84 that is arranged so as to close the opening of the recess 75C and is made of a light-transmitting material. The blocking member 84 reflects a part of the measurement light SL2 emitted from the reflection surface 82 toward the sixth mirror 33 so as to return to the reflection surface 82 side, and transmits the remaining measurement light SL2. Is formed. The reference surface 85 is a plane that is substantially orthogonal to the optical path of the measurement light SL2 incident on the reference surface 85, and the height difference between the concave portion and the convex portion is 1/20 or less of the wavelength of the measurement light SL2. Is processed (for example, polished). Most of the measurement light SL2 reflected by the reference surface 85 enters the through hole 75B on the side wall of the lens barrel 40 via the reflection surface 82, and is emitted from the opening end on the + Z direction side of the through hole 75B. After that, the light is reflected toward the radial observation unit 80 by the optical surface 77 of the first beam splitter 78 in the interferometer housing space 75A. Note that a non-reflective coating may be formed on the surface of the closing member 84 opposite to the reference surface 85.

  In addition, in the sixth mirror 33, a test surface 86 that is substantially parallel to the reference surface 85 is formed (polished or the like) in a region that is not incident on the exposure light EL and that faces the blocking member 84. Has been. Then, most of the measurement light SL2 reflected by the test surface 86 enters the through hole 75B on the side wall of the lens barrel 40 via the reflective surface 82, and from the opening end of the through hole 75B on the + Z direction side. After being emitted, the light is reflected toward the radial observation unit 80 by the optical surface 77 of the first beam splitter 78 in the interferometer housing space 75A. At this time, the measurement light SL2 reflected by the test surface 86 and the measurement light SL2 reflected by the reference surface 85 interfere with each other. That is, the radial direction observation unit 80 can measure the interference fringes according to the difference (that is, the distance H2) between the reference surface 85 and the test surface 86.

  Note that the measuring device 60 of the present embodiment includes a radial interferometer for measuring the positions in the radial direction of the mirrors 28 to 30 and 32 other than the sixth mirror 33 arranged in the cylindrical portion of the lens barrel 40. Is provided. Since these axial interferometers have substantially the same configuration as the axial interferometer 61 for the sixth mirror 33, the description of these configurations is omitted.

  6 and 7 show a portion for measuring the position of the fourth mirror 31 in the radial direction in the measuring device 60. That is, the flange 41 is formed with an interferometer housing space 90A that is open on the −Z direction side and closed on the + Z direction side. The interferometer housing space 90A has an axial interferometer 61 and a diameter in the circumferential direction. It is arranged at a position different from the direction interferometer 75. A radial interferometer 90 for measuring the radial position of the fourth mirror 31 with respect to the side wall of the lens barrel 40 is provided at the same position in the radial direction as the interferometer housing space 90A. The radial interferometer 90 is provided with a radial light emitting portion 91 that is arranged radially outside the interferometer accommodating space 90A and outputs the measurement light SL3 toward the inside in the radial direction. The radial light emitting portion 91 is disposed on the −Z direction side in the interferometer housing space 90A.

  Further, in the interferometer housing space 90A, on the radially inner side of the radial light emitting portion 91, the first optical element is arranged so that the incident angle of the measurement light SL3 output from the radial light emitting portion 91 is 45 °. A first beam splitter 93 having a surface 92 is provided. The first beam splitter 93 is supported by the flange 41 via a support portion (not shown). Then, most of the measurement light SL3 incident on the first optical surface 92 from the radial light emitting portion 91 side passes through the first optical surface 92 and is then emitted radially inward. Further, in the interferometer housing space 90A, on the + Z direction side of the first beam splitter 93, a radial direction observation unit 95 that is supported by the + Z direction side portion 41b of the flange 41 and has an imaging element such as a CCD is provided. The observation result by the radial direction observation unit 95 is output to the control device 130 described later.

  Further, in the interferometer housing space 90A, a second optical surface 96 that reflects a part of the measurement light SL3 output from the radial light emitting unit 91 to the −Z direction side is provided on the radially inner side of the first beam splitter 93. A second beam splitter 97 is provided. The second beam splitter 97 is supported by the flange 41 via a support portion (not shown). Further, in the + Z direction side portion 41 b of the flange 41, a communication hole 90 </ b> B that allows the inside and outside of the interferometer housing space 90 </ b> A to communicate is formed at the same radial position as the second beam splitter 97.

  An extending member 103 extending in the −Z direction side is provided on the −Z direction side of the flange 41 and on the −Z direction side of the second beam splitter 97, and in the extending member 103, the Z A through hole 103a extending along the axial direction is formed through. The extending member 103 is made of a material having a linear thermal expansion coefficient that is N times (N is a value larger than 1, for example, 10 times) a linear thermal expansion coefficient of a material constituting the rod member 99 described later. It is configured. The length L2 of the extending member 103 in the Z-axis direction is 1 / N times (for example, 0.1 times) the length L1 of the rod member 99 in the Z-axis direction. In addition, the second reflecting member 104A having a reference surface 104 that totally reflects the measurement light SL3 having the inside of the through hole 103a as an optical path at the tip (that is, the end on the −Z direction side) of the extending member 103. Is provided. The reference surface 104 of the second reflecting member 104A is a plane substantially orthogonal to the optical path of the measurement light SL3 incident on the reference surface 104, and the difference in height between the concave portion and the convex portion is 1 of the wavelength of the measurement light SL3. / 20 or less (eg, polished).

  The measurement light SL3 emitted from the second optical surface 96 of the second beam splitter 97 to the −Z direction side enters the through hole 103a of the extending member 103. Then, the measurement light SL3 travels in the longitudinal direction (that is, the Z-axis direction) in the through hole 103a of the extending member 103 and is reflected by the reference surface 104. Then, the measurement light SL3 reflected by the reference surface 104 travels in the through hole 103a of the extending member 103 toward the −Z direction side and is emitted from the opening end of the through hole 103a on the + Z direction side. After that, a part of the measurement light SL3 passes through the second beam splitter 97 and is then emitted out of the flange 41 from the communication hole 90B. The remaining measurement light SL3 is guided to the radial observation unit 95 via the second optical surface 96 of the second beam splitter 97 and the first optical surface 92 of the first beam splitter 93.

  Further, a rod member 99 that extends to the + Z direction side and is made of the same material as the lens barrel 40 (that is, a low thermal expansion material) is located on the + Z direction side of the flange 41 and opposed to the communication hole 90B. Is provided. The tip of the rod member 99 (that is, the end on the + Z direction side) is located at substantially the same position as the fourth mirror 31 in the Z-axis direction. Further, a through hole 99a extending along the Z-axis direction is formed through the rod member 99, and the through hole 99a communicates with the communication hole 90B. Then, the measurement light SL3 transmitted through the second beam splitter 97 and emitted from the communication hole 90B enters the through hole 99a of the rod member 99, and the inside of the through hole 99a is in its longitudinal direction (that is, the Z-axis direction). ) Follow along. Further, the rod member 99 has a first reflecting member 100A having a first reflecting surface 100 for emitting measurement light SL3 emitted from the opening end of the through hole 99a on the + Z direction side toward the radially outer side. Is provided. The first reflecting surface 100 of the first reflecting member 100A is positioned such that the incident angle of the measurement light SL3 emitted from the through hole 99a of the rod member 99 is approximately 45 °.

  The measurement light SL3 emitted from the first reflecting surface 100 of the first reflecting member 100A toward the radially outer side is returned to the + Z direction side of the fourth mirror 31 (that is, the side where the exposure light EL is not incident). A reflection mirror 102 having a test surface 101 that totally reflects is provided. The test surface 101 of the reflection mirror 102 is a plane that is substantially orthogonal to the optical path of the measurement light SL3 incident on the test surface 101 and is parallel to the X-axis direction passing through the central axis 31a of the fourth mirror 31. It is located on the line 31b. The measurement light SL3 reflected by the test surface 101 is reflected to the −Z direction side by the first reflecting surface 100 of the first reflecting member 100A, and passes through the first reflecting surface 100 and enters the through hole 99a of the rod member 99. And travels in the through hole 99a toward the −Z direction side. Then, most of the measurement light SL3 emitted from the opening end on the −Z direction side of the through hole 99a enters the interferometer housing space 90A through the communication hole 90B, and then the second beam splitter 97 The second optical surface 96 and the first optical surface 92 of the first beam splitter 93 are guided to the radial direction observation unit 95 side. At this time, the measurement light SL3 reflected by the test surface 101 and the measurement light SL3 reflected by the reference surface 104 interfere with each other. That is, the radial direction observation unit 95 can measure the interference fringes according to the difference between the rod member 99 and the test surface 101 (that is, the distance H3).

  Here, since the rod member 99 and the extending member 103 are respectively fixed to the flange 41, it can be said that each has a temperature substantially equal to the temperature of the lens barrel 40. The rod member 99 is made of the same material as the lens barrel 40. Therefore, if the lens barrel 40 is thermally expanded, the thermal expansion amount (extension amount) of the rod member 99 in the Z-axis direction is substantially equal to the thermal expansion amount of the lens barrel 40 in the Z-axis direction. On the other hand, the extending member 103 is made of a material whose linear thermal expansion coefficient is N times that of the material constituting the lens barrel 40 and the rod member 99, and its length in the Z-axis direction is the Z-axis of the rod member 99. 1 / N times the length in the direction. Therefore, if the rod member 99 is thermally expanded in the Z-axis direction, the thermal expansion amount of the extending member 103 in the Z-axis direction is substantially equal to the thermal expansion amount of the rod member 99 in the Z-axis direction. Therefore, it is possible to cancel the thermal expansion of the rod member 99 in the Z-axis direction.

  FIG. 8 shows a diameter measuring interferometer 110 that measures the diameter of the inner peripheral surface of the lens barrel 40 in the measuring device 60. The diameter measuring interferometer 110 is arranged at a position different from the axial interferometer 61, the radial interferometer 75, and the radial interferometer 90 in the circumferential direction. That is, a diameter measuring accommodation space 110 </ b> A is formed at a position different from the axial interferometer 61, the radial interferometer 75, and the radial interferometer 90 in the circumferential direction in the flange 41. In the diameter measurement storage space 110A, a diameter measurement light emitting unit that outputs the measurement light SL4 in a second direction that is a direction perpendicular to the Z-axis direction and toward the central axis AX of the lens barrel 40. 112 is provided.

  The first beam splitter 115 has an optical surface 114 on which the measurement light SL4 is incident on the optical path of the measurement light SL4 output from the diameter measurement light emitting unit 112 inside the diameter measurement storage space 110A in the radial direction. Is provided. The optical surface 114 of the first beam splitter 115 is arranged so that the incident angle of the measurement light SL4 output from the diameter measurement light emitting unit 112 is 45 °. Then, most of the measurement light SL4 incident on the optical surface 114 from the diameter measurement light emitting unit 112 side passes through the optical surface 114 and then passes through the lens barrel 40 in the second direction (upward in FIG. 8). And proceed.

  In addition, a diameter measurement observation unit 117 having an imaging element such as a CCD is provided on the side of the first beam splitter 115 in the diameter measurement storage space 110A. The diameter measurement observation unit 117 is arranged so that light incident from the optical surface 114 side of the first beam splitter 115 can be observed. Then, the observation result by the diameter measuring observation unit 117 is output to the control device 130 described later.

  A plate-like reference member 118 made of a translucent material is provided on the inner surface side of the flange 41 and at the same collection direction position as the first beam splitter 115 in the circumferential direction. The reference member 118 includes a reference surface 119 that reflects part of the measurement light SL4 output from the diameter measurement light emitting unit 112 so as to return to the first beam splitter 115 side and transmits the remaining measurement light SL4. Is formed. The reference surface 119 is a plane substantially orthogonal to the optical path of the measurement light SL4 incident on the reference surface 119, and the height difference between the concave portion and the convex portion is 1/20 or less of the wavelength of the measurement light SL4. Is processed (for example, polished). Further, a non-reflective coating may be formed on the surface of the reference member 118 opposite to the reference surface 119.

  On the inner side surface of the flange 41, a test surface 120 is processed and formed on the opposite side of the diameter measuring light emitting portion 112 with the central axis AX interposed therebetween. On the test surface 120, a reflection coat for totally reflecting the incident measurement light SL4 is formed. Most of the measurement light SL4 reflected by the test surface 120 travels to the first beam splitter 115 side along the second direction, and is then reflected by the optical surface 114 to the diameter measurement observation unit 117 side. . At this time, the measurement light SL4 reflected by the test surface 120 and the measurement light SL4 reflected by the reference surface 119 interfere with each other. That is, the diameter measuring observation unit 117 can measure the interference fringes according to the difference between the reference surface 119 and the test surface 120.

Next, a control apparatus that controls the exposure apparatus 11 of the present embodiment will be described with reference to FIG.
As shown in FIG. 9, a measuring device 60 is electrically connected to an input side interface (not shown) of the control device 130. Further, the mirror holding devices 43A to 43F (more specifically, the actuator 55 in the link 50) are electrically connected to an output side interface (not shown) of the control device 130. The control device 130 includes a computer 131 constructed from a CPU, a ROM, a RAM, and the like, an axial direction calculation unit 132 for calculating the positions of the mirrors 28 to 33 in the Z axis direction, and the mirrors 28 to 33. And a radial direction calculation unit 133 for calculating a position in the radial direction.

  The computer 131 individually controls the driving of the mirror holding devices 43A to 43F based on the calculation results of the calculation units 132 and 133. That is, based on a control command from the computer 131, the positions and orientations of the mirrors 28 to 33 are adjusted.

  An observation result is input to the axial direction calculation unit 132 as an electrical signal from the axial direction observation unit 66 of each axial interferometer 61 provided for each of the mirrors 28 to 33. That is, the axial direction calculation unit 132 calculates the position of each mirror 28 to 33 in the Z-axis direction based on the interference fringes observed by each axial direction observation unit 66. Here, since the lens barrel 40 of the present embodiment is made of a material having a very low linear thermal expansion coefficient, the lens barrel 40 hardly thermally expands. Therefore, the axial direction calculation unit 132 of the present embodiment can individually calculate the positions in the Z-axis direction of the mirrors 28 to 33 with respect to the surface 41a on the −Z direction side of the flange 41.

  The radial direction calculation unit 133 includes a radial direction observation unit 80 of the radial direction interferometer 75 provided for each of the mirrors 28 to 30, 32, and 33, and a radial direction observation unit 95 of the radial direction interferometer 90 for the fourth mirror 31. The observation result is input as an electric signal from the diameter measurement observation unit 117 of the diameter measurement interferometer 110. That is, the radial direction calculation unit 133 is configured so that each of the mirrors 28 to 30, 32, 33 on the XY plane in the barrel 40 is based on the interference fringes observed by the radial direction observation unit 80 of each radial interferometer 75. Calculate the position individually. As described above, the lens barrel 40 of the present embodiment hardly thermally expands. Therefore, the radial direction calculation unit 133 according to the present embodiment can individually calculate the positions of the mirrors 28 to 30, 32, and 33 on the XY plane with the central axis AX of the lens barrel 40 as a reference.

  Further, the radial direction calculation unit 133 calculates the diameter of the lens barrel 40 based on the interference fringes observed by the diameter measurement observation unit 117 of the diameter measurement interferometer 110, and determines the mirror from the central axis AX of the lens barrel 40. A distance to the inner surface 40a of the cylinder 40 (that is, a radius, hereinafter referred to as a first distance) is calculated. Further, the radial direction calculation unit 133 is based on the interference fringes observed by the radial direction observation unit 95 of the radial interferometer 90, and the distance from the side wall of the lens barrel to the central axis 31a of the fourth mirror 31 (hereinafter, second Called distance). Then, the radial direction calculation unit 133 adds the first distance, the second distance, and the thickness of the lens barrel 40, thereby determining the position of the fourth mirror 31 on the XY plane with respect to the central axis AX of the lens barrel 40. calculate.

Therefore, in this embodiment, the following effects can be obtained.
(1) Since the lens barrel 40 is made of a low thermal expansion material, it is difficult to thermally expand. Therefore, the displacement due to the thermal expansion of the lens barrel 40 of the mirrors 28 to 33 supported by the lens barrel 40 via the mirror holding devices 40A to 40F is suppressed. The projection optical system 16 of the present embodiment is provided with a measuring device 60 that measures the positions of the mirrors 28 to 33 with respect to the lens barrel 40. Therefore, even during the exposure process, the positions of the mirrors 28 to 33 with respect to the lens barrel 40 can be measured. Therefore, the wavefront aberration of the projection optical system 16 can be suitably maintained while maintaining the efficiency of the lithography process.

  (2) The mirrors 28 to 33 supported by the lens barrel 40 via the mirror holding devices 40A to 40F are the outer ring 46, the inner ring 48, the holding mechanisms 49, and the links 50 that constitute the mirror holding devices 40A to 40F. May be displaced by thermal deformation. Conventionally, the lens barrel (hereinafter, also referred to as a conventional lens barrel) is likely to thermally expand because the constituent material has a higher linear thermal expansion coefficient than the lens barrel 40 of the present embodiment. For this reason, the mirrors 28 to 33 may be displaced by the thermal expansion of the conventional lens barrel. In this regard, in this embodiment, the lens barrel 40 hardly thermally expands. Therefore, it can be said that the projection optical system 16 of the present embodiment has a configuration in which the mirrors 28 to 33 are not easily displaced unnecessarily.

  (3) Moreover, the projection optical system 16 of the present embodiment is provided with a measuring device 60 for measuring the positions of the mirrors 28 to 33 with respect to the lens barrel 40. Therefore, the displacement of the mirrors 28 to 33 due to the thermal deformation of the outer ring 46, the inner ring 48, each holding mechanism 49, and each link 50 can be measured quickly. And by controlling the drive of the mirror holding devices 40A to 40F based on this measurement result, the displacement of the mirrors 28 to 33 can be quickly eliminated.

  (4) The flange 41 of the lens barrel 40 is not movable with respect to the wafer W held on the wafer stage 17. In the present embodiment, the positions of the mirrors 28 to 33 in the Z-axis direction with respect to the flange 41 are measured using the axial interferometers 61. Therefore, the optical characteristics of the projection optical system 16 can be favorably maintained by adjusting the positions of the mirrors 28 to 33 in the Z-axis direction.

  (5) An optical path (hereinafter also referred to as a Z-axis optical path) extending in the Z-axis direction in the optical paths of the measurement light beams SL <b> 1 to SL <b> 3 is provided in a through hole formed in the side wall of the lens barrel 40. Therefore, as compared with the case where the Z-axis optical path of each measurement light SL1 to SL3 is provided outside the side wall of the lens barrel 40, it is easier to avoid the intersection of the optical path of each measurement light SL1 to SL3 and the optical path of the exposure light EL. Accordingly, the positions of the mirrors 28 to 33 can be measured even during the exposure process.

  (6) The radial interferometer 90 includes a rod member 99 and an extending member 103 having a thermal expansion amount substantially equal to the thermal expansion amount of the rod member 99, and a reference surface at the tip of the extending member 103 104 is provided. Therefore, even if the lens barrel 40 is thermally expanded in the Z-axis direction, the thermal expansion can be canceled and the position of the fourth mirror 31 on the XY plane can be measured.

  (7) The interferometers 61 and 75 have a configuration in which the reference surfaces 68 and 85 are arranged closer to the test surfaces 70 and 86 than the light emitting units 62 and 76. Therefore, it is possible to suppress the generation of detection errors due to slight thermal expansion of the lens barrel 40.

The above embodiment may be changed to another embodiment as described below.
-In embodiment, the structure provided with a linear encoder may be sufficient as the measurement part for measuring the position in the Z-axis direction of the mirrors 28-33. That is, as shown in FIGS. 10A and 10B, the measurement unit includes a strip-shaped film member 140 extending along the Z-axis direction, and the film member 140 is disposed on the inner surface 40 a side of the lens barrel 40. Is provided. The film member 140 is formed with a plurality of slits 141 arranged at equal intervals along the longitudinal direction. In addition, the measurement unit includes a holding member 142 provided on the side wall of a mirror (for example, the sixth mirror 33), and a proximal end of the holding member 142 is fixed to the sixth mirror 33. Further, the front end of the holding member 142 is a pair of holding portions 142a and 142b branched in a bifurcated shape, and the both holding portions 142a and 142b respectively sandwich the film member 140 from the left and right sides in FIG. Has been placed. The first holding unit 142 a is provided with a light emitting unit 143 that emits measurement light, and the second holding unit 142 b is provided with a light receiving unit 144 that receives measurement light through the slit 141 of the film member 140. ing. The light receiving unit 144 is electrically connected to the control device 130, and the axial direction calculation unit 132 of the control device 130 calculates the position of the sixth mirror 33 in the Z-axis direction based on the electrical signal from the light receiving unit 144. To do.

  Even if comprised in this way, the lens-barrel 40 holding the film member 140 hardly thermally expands. Therefore, the interval between the slits 141 adjacent to each other in the Z-axis direction hardly changes. Therefore, the position of the sixth mirror 33 in the Z-axis direction can be accurately detected.

The member in which the plurality of slits 141 are formed may be a rod-shaped member made of the same material as that of the lens barrel 40, for example, instead of the film member.
-In embodiment, the structure provided with the electrostatic capacitance sensor may be sufficient as the measurement part for measuring the space | interval of the mirrors 28-31 and 33 and the inner surface 40a of the lens-barrel 40. FIG.

  In the embodiment, a through hole is formed in the side wall of the lens barrel 40, and the inside of the through hole is used as an optical path of measurement light. However, a concave groove extending in the Z-axis direction is formed in the side wall of the lens barrel 40, and the concave groove The inside may be used as an optical path of measurement light.

  In the embodiment, each interferometer 61, 75, 90 has a configuration in which the reference surfaces 68, 85, 104 are arranged closer to the test surfaces 70, 86, 101 than the light emitting units 62, 76, 91. The reference surfaces 68, 85, 104 may be arranged closer to the light emitting units 62, 76, 91 than the test surfaces 70, 86, 101. For example, each interferometer 61, 75, 90 has a configuration in which the light emitting units 62, 76, 91, the reference surfaces 68, 85, 104, the first beam splitters 64, 78.93, and the observation units 66, 80, 95 are unitized. It may be.

  In the embodiment, the measurement device 60 may omit the diameter measurement interferometer 110. Even if it comprises in this way, since the lens-barrel 40 hardly thermally expands, the diameter hardly changes. Therefore, by previously storing the diameter of the lens barrel 40 in a storage device (not shown), the position of the fourth mirror 31 relative to the lens barrel 40 on the XY plane can be measured.

  In the embodiment, the measurement device 60 may be configured such that the position of the mirrors 28 to 33 on the XY plane cannot be measured as long as the position of the mirrors 28 to 33 in the Z-axis direction can be measured. In this case, the measuring device 60 may omit the radial interferometers 75 and 90 and the diameter measuring interferometer 110.

-In embodiment, the material which comprises the lens-barrel 40 may be arbitrary low thermal expansion materials, if a linear thermal expansion coefficient is 1.0x10 < ^-6 > / degrees C or less. For example, ULE (registered trademark) or clear serum (registered trademark) may be used.

-In embodiment, the material which comprises the lens-barrel 40 may be non-light-transmitting ceramics.
In the embodiment, the exposure apparatus 11 is for manufacturing a reticle or mask used not only in a micro device such as a semiconductor element but also in an optical exposure apparatus, an EUV exposure apparatus, an X-ray exposure apparatus, and an electron beam exposure apparatus. In addition, an exposure apparatus that transfers a circuit pattern from a mother reticle to a glass substrate, a silicon wafer, or the like may be used. The exposure apparatus 11 is used for manufacturing a display including a liquid crystal display element (LCD) and the like, and is used for manufacturing an exposure apparatus that transfers a device pattern onto a glass plate, a thin film magnetic head, and the like. It may be an exposure apparatus that transfers to a wafer or the like, and an exposure apparatus that is used to manufacture an image sensor such as a CCD.

In the embodiment, the light source device 12 includes, for example, g-line (436 nm), i-line (365 nm), KrF excimer laser (248 nm), F ₂ laser (157 nm), Kr ₂ laser (146 nm), Ar ₂ laser (126 nm) The light source which can supply etc. may be sufficient. The light source device 12 amplifies the infrared or visible single wavelength laser light oscillated from the DFB semiconductor laser or fiber laser, for example, with a fiber amplifier doped with erbium (or both erbium and ytterbium). Alternatively, a light source capable of supplying harmonics converted into ultraviolet light using a nonlinear optical crystal may be used.

  When such light is used as the exposure light EL, the inside of the chamber 13 need not be in a vacuum atmosphere. In this case, if the Z-axis optical path of each measurement light SL1 to SL3 is provided outside the side wall of the lens barrel 40, the gas in the lens barrel 40 may fluctuate due to the measurement light SL1 to SL3. In this respect, by providing the Z-axis optical path of each of the measurement lights SL1 to SL3 in the side wall of the lens barrel 40, the occurrence of gas fluctuation in the lens barrel 40 can be suppressed, and the occurrence of vibration of the optical element due to the fluctuation can be suppressed. Can be suppressed.

In the embodiment, the light source device 12 may be a device having a discharge plasma light source.
In the embodiment, the exposure apparatus 11 may be embodied as a step-and-repeat apparatus.

  Next, an embodiment of a microdevice manufacturing method using the device manufacturing method by the exposure apparatus 11 of the embodiment of the present invention in the lithography process will be described. FIG. 11 is a flowchart illustrating a manufacturing example of a micro device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micro machine, or the like).

  First, in step S101 (design step), function / performance design (for example, circuit design of a semiconductor device) of a micro device is performed, and pattern design for realizing the function is performed. Subsequently, in step S102 (mask manufacturing step), a mask (reticle R or the like) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S103 (substrate manufacturing step), a substrate (a wafer W when a silicon material is used) is manufactured using a material such as silicon, glass, or ceramics.

  Next, in step S104 (substrate processing step), using the mask and substrate prepared in steps S101 to S104, an actual circuit or the like is formed on the substrate by lithography or the like, as will be described later. Next, in step S105 (device assembly step), device assembly is performed using the substrate processed in step S104. Step S105 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary. Finally, in step S106 (inspection step), inspections such as an operation confirmation test and a durability test of the microdevice manufactured in step S105 are performed. After these steps, the microdevice is completed and shipped.

FIG. 12 is a diagram illustrating an example of a detailed process of step S104 in the case of a semiconductor device.
In step S111 (oxidation step), the surface of the substrate is oxidized. In step S112 (CVD step), an insulating film is formed on the substrate surface. In step S113 (electrode formation step), an electrode is formed on the substrate by vapor deposition. In step S114 (ion implantation step), ions are implanted into the substrate. Each of the above steps S111 to S114 constitutes a pretreatment process at each stage of the substrate processing, and is selected and executed according to a necessary process at each stage.

  When the above-mentioned pretreatment process is completed in each stage of the substrate process, the posttreatment process is executed as follows. In this post-processing process, first, in step S115 (resist formation step), a photosensitive material is applied to the substrate. Subsequently, in step S116 (exposure step), the circuit pattern of the mask is transferred to the substrate by the lithography system (exposure apparatus 11) described above. Next, in step S117 (development step), the substrate exposed in step S116 is developed to form a mask layer made of a circuit pattern on the surface of the substrate. Subsequently, in step S118 (etching step), the exposed member other than the portion where the resist remains is removed by etching. In step S119 (resist removal step), the photosensitive material that has become unnecessary after the etching is removed. That is, in step S118 and step S119, the surface of the substrate is processed through the mask layer. By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the substrate.

  DESCRIPTION OF SYMBOLS 11 ... Exposure apparatus, 14 ... Illumination optical system, 16 ... Projection optical system, 28-33 ... Mirror as an optical element, 31a ... Center axis as an optical axis, 40 ... Lens barrel, 41 ... Flange, 43A-43F ... Optical Mirror holding device as element holding device, 55 ... Actuator, 60 ... Measuring device, 61 ... Axial interferometer (first interferometer) constituting first measuring unit, 62 ... Axial light emitting unit as first light emitting unit , 66... An axial observation unit as a first observation unit, 68... A reference surface as a first reference surface, 70... A test surface as a first mirror unit, 75. Radial direction interferometer (second interferometer), 76, 91... Radial direction light emitting portion as second light emitting portion, 80, 95... Radial direction observation portion as second observation portion, 85, 104. Reference plane, 86, 101 ... test as second mirror part , 90... Second measuring unit, radial interferometer (second interferometer) constituting the interval detecting unit, 96... Second optical surface as a branching unit, 103... Extension member, 110. Diameter measuring interferometer constituting detection unit, 130 ... control device, 131 ... computer as control unit, 132 ... axial direction calculation unit (first calculation unit) constituting first measurement unit, 133 ... second measurement unit AX ... the central axis of the lens barrel, EL ... exposure light as a radiation beam, R ... reticle as a mask, SL1 to SL4 ... measurement light, W ... wafer as a substrate.

Claims (19)

A lens barrel made of a low thermal expansion material;
An optical element disposed in the lens barrel;
An optical element holding device having a drive unit that holds the optical element and drives the optical element to move with respect to the lens barrel;
A measuring device for measuring the position of the optical element with respect to the lens barrel;
An optical system comprising: a control unit that controls the optical element holding device based on a measurement result of the measurement device. 2. The optical system according to claim 1, wherein the lens barrel is made of a low thermal expansion material having a linear thermal expansion coefficient of 1.0 × 10 ⁻⁶ / ° C. or less. The optical system according to claim 2, wherein the lens barrel is made of a low thermal expansion material. The lens barrel has a reference portion,
The said measuring apparatus has a 1st measurement part which measures the position of the said optical element in the 1st direction along the center axis | shaft of the said lens-barrel on the basis of the said reference | standard site | part. The optical system according to any one of the above. The first measurement unit includes: a first interferometer; and a first calculation unit that calculates a position of the optical element with respect to the reference portion in the first direction based on an interference fringe observed by the first interferometer. The optical system according to claim 4, wherein the optical system is provided. The first interferometer is incident with a first light emitting unit that emits measurement light, a first observation unit, and a first reference surface that reflects at least part of the incident measurement light toward the first observation unit. A first mirror part that reflects at least a part of the measurement light to the first observation part side,
The first observation unit is capable of observing interference fringes formed by reflected light from the first reference surface and the first mirror unit, and on either the reference region side or the optical element side. Arranged,
The optical system according to claim 5, wherein the first mirror unit is disposed on the other side of the reference portion side and the optical element side. The optical system according to claim 6, wherein the first observation unit is disposed on the reference site side, and the first mirror unit is formed by processing a part of the optical element. system. 8. The optical system according to claim 6, wherein the first reference surface is arranged closer to the first mirror part than the first observation part in the first direction. 9. The lens barrel is made of a low thermal expansion material,
The optical system according to any one of claims 6 to 8, wherein the first reference surface is formed by processing a part of a side wall of the lens barrel. The lens barrel has a cylindrical portion, and the optical element is disposed such that an optical axis thereof is spaced apart from a central axis of the lens barrel by a predetermined distance.
The measurement apparatus further includes a second measurement unit that measures a position of the optical axis of the optical element with respect to a central axis of the barrel in a second direction intersecting the first direction,
The second measurement unit includes a diameter detection unit that detects a diameter of the cylindrical portion, an interval detection unit that detects an interval between a side wall of the cylindrical portion and a detection position of the optical element, and detection results obtained by the detection units. 5. The optical system according to claim 4, further comprising: a second calculation unit that calculates a position of an optical axis of the optical element with respect to a central axis of the barrel in the second direction based on the optical system. The interval detection unit includes a second interferometer, and an interval calculation unit that calculates an interval between the side wall of the cylindrical portion and the detection position of the optical element based on an interference fringe observed by the second interferometer. The optical system according to claim 10. The second interferometer includes a second light-emitting unit arranged so that an optical path of measurement light extends along the first direction, a second observation unit arranged at the reference part, and at least incident measurement light A second reference surface that partially reflects to the second observation unit side, and a second mirror that is disposed at the detection position of the optical element and reflects at least a part of incident measurement light to the second observation unit side And
The optical system according to claim 11, wherein the second observation unit is capable of observing interference fringes formed by each reflected light from the second reference surface and the second mirror unit. The lens barrel is made of a low thermal expansion material,
The optical system according to claim 12, wherein the second light emitting unit is arranged such that an optical path of measurement light to be emitted is formed in a side wall of the lens barrel. The optical system according to claim 13, wherein the second reference surface is disposed at a position closer to the second mirror unit than the observation unit in the first direction. An extension member extending along the first direction from the reference portion;
The interval detection unit is arranged at a position different from the base end in the first direction in the second light emitting unit for emitting measurement light, the second observation unit arranged in the reference region, and the extending member. And a second reference surface that reflects at least a part of the incident measurement light to the second observation part side, and at least a part of the measurement light that is provided on the optical element and is incident on the second observation part side A second mirror part that reflects, and a branch part that branches measurement light from the second light emitting part to the second reference plane and the second mirror part,
The optical system according to claim 10, wherein the second observation unit is capable of observing interference fringes formed by reflected light from the second reference surface and the second mirror unit. The linear thermal expansion coefficient of the material constituting the extending member is N (N is a value greater than 1) times the linear thermal expansion coefficient of the low thermal expansion material constituting the barrel,
The length of the extending member in the first direction is 1 / N times the length corresponding to the distance between the reference portion and the second mirror portion in the first direction. 15. The optical system according to 15. 17. The optical system according to claim 15, wherein the extending member is disposed so as to extend from the reference portion to a side opposite to a position where the optical element is disposed in the first direction. . An illumination optical system for directing a radiation beam to a mask on which a predetermined pattern is formed;
A projection optical system that irradiates a substrate coated with a photosensitive material with a radiation beam through the mask, and
An exposure apparatus, wherein at least one of the optical systems includes the optical system according to any one of claims 1 to 17. In a device manufacturing method including a lithography process,
A device manufacturing method using the exposure apparatus according to claim 18 in the lithography process.

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