JP2014236121A - Mirror device, extreme-ultraviolet light generator and extreme-ultraviolet light generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress pulse laser light from being outputted to an external exposure device.SOLUTION: A mirror device includes a substrate part where a concave surface is formed on one side, and a multilayer reflection film located on the concave surface and having a plurality of grooves formed in the surface. The plurality of grooves are formed so that the depth in a second region, farther from the center of the concave surface than the first region, becomes larger than the depth in the first region.

Description

  The present disclosure relates to a mirror device, an extreme ultraviolet light generation device, and an extreme ultraviolet light generation system.

  In recent years, along with miniaturization of semiconductor processes, miniaturization of transfer patterns in optical lithography of semiconductor processes has been rapidly progressing. In the next generation, fine processing of 70 nm to 45 nm, and further fine processing of 32 nm or less will be required. For this reason, for example, in order to meet the demand for fine processing of 32 nm or less, an extreme ultraviolet light generation device for generating extreme ultraviolet (EUV) light having a wavelength of about 13 nm and a reduced projection reflective optics (reduced projection reflective optics). ) Is expected to be developed.

  As an extreme ultraviolet light generation apparatus, an LPP (Laser Produced Plasma) type apparatus in which plasma generated by irradiating a target material with laser light is used, and DPP in which plasma generated by discharge is used. Three types of devices have been proposed: (Discharge Produced Plasma) type devices and SR (Synchrotron Radiation) type devices using orbital radiation.

US Pat. No. 8,1986,613 US Patent Application Publication No. 2011/0223543 US Patent Application Publication No. 2013/0001442

Overview

  A mirror device according to one aspect of the present disclosure includes a substrate portion having a concave portion formed on one surface thereof, and a multilayer reflective film that is positioned on the concave surface portion and has a plurality of grooves formed on a surface thereof. The groove may be formed so that the depth in the second region farther from the center of the concave portion than in the first region is larger than the depth in the first region.

  An extreme ultraviolet light generation device according to another aspect of the present disclosure includes a chamber provided with a through hole, a target generation unit configured to output a target in the chamber, and a pulse in the chamber through the through hole. You may provide the laser condensing optical system comprised so that a laser beam may be introduced, and the mirror apparatus which condenses the extreme ultraviolet light produced | generated in the chamber. The mirror device includes a substrate portion having a concave surface portion formed on one surface, and a multilayer reflective film that is located on the concave surface portion and has a plurality of grooves formed on a surface thereof, wherein the plurality of grooves have a depth in the first region. In addition, the depth in the second region farther from the center of the concave surface portion than the first region may be formed.

  An extreme ultraviolet light generation system according to another aspect of the present disclosure includes a laser device that generates pulsed laser light, a chamber provided with a through-hole, and a target generation configured to output a target in the chamber A laser condensing optical system configured to introduce a pulse laser beam into the chamber through the through-hole, and a mirror device that condenses the extreme ultraviolet light generated in the chamber. The mirror device includes a substrate portion having a concave surface portion formed on one surface, and a multilayer reflective film that is located on the concave surface portion and has a plurality of grooves formed on a surface thereof, wherein the plurality of grooves have a depth in the first region. In addition, the depth in the second region farther from the center of the concave surface portion than the first region may be formed.

Several embodiments of the present disclosure are described below by way of example only and with reference to the accompanying drawings.
FIG. 1 schematically shows the configuration of an exemplary LPP type EUV light generation system. FIG. 2 is a partial cross-sectional view showing the configuration of the EUV light generation system according to the first embodiment. FIG. 3A is a plan view of an EUV collector mirror used in the first embodiment, and FIG. 3B is a cross-sectional view of the EUV collector mirror shown in FIG. 3A along the line IIIB-IIIB. FIG. 4 shows an enlarged part of the cross section of the EUV collector mirror shown in FIG. 3B. FIG. 5 shows an enlarged part of a section of the EUV collector mirror shown in FIG. FIG. 6 shows the optical path of the first direction component when the incident angle of the pulse laser beam is different from that shown in FIG. FIG. 7 shows a preferable groove depth when the pulsed laser beam is a CO ₂ laser beam in relation to the incident angle to the multilayer reflective film. FIG. 8 shows a preferable range of the groove depth when the pulse laser beam is a CO ₂ laser beam in relation to the incident angle to the multilayer reflective film. The processing apparatus for manufacturing the EUV collector mirror used in 1st Embodiment is shown schematically. FIG. 10 shows an enlarged part of a cross section of the EUV collector mirror used in the second embodiment. FIG. 11 schematically shows a processing apparatus for manufacturing an EUV collector mirror used in the second embodiment. FIG. 12A is a plan view of an EUV collector mirror used in the third embodiment, and FIG. 12B is a cross-sectional view taken along the line XIIB-XIIB of the EUV collector mirror shown in FIG. 12A.

Embodiment

<Contents>
1. Outline 2. 2. Overall description of EUV light generation system 2.1 Configuration 2.2 Operation EUV light generation system including EUV collector mirror formed with diffraction grating 3.1 Configuration 3.2 Operation 3.3 EUV collector mirror formed with diffraction grating 3.4 Distance from substrate center and groove depth 3.5 Manufacturing method 4. EUV collector mirror with reduced thickness of second layered portion 4.1 Configuration 4.2 Manufacturing method 5. EUV collector mirror having a diffraction grating formed on a part of the reflecting surface Other

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Embodiment described below shows some examples of this indication, and does not limit the contents of this indication. In addition, not all of the configurations and operations described in the embodiments are essential as the configurations and operations of the present disclosure. In addition, the same referential mark is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

1. Outline In an LPP type EUV light generation apparatus, a target generation unit may output a droplet-shaped target to reach a plasma generation region in a chamber. When the target reaches the plasma generation region, the laser device irradiates the target with pulsed laser light, whereby the target is turned into plasma, and radiation light including EUV light can be emitted from the plasma. The EUV light included in the emitted light may be output to an external exposure apparatus via an intermediate condensing point by being reflected by an EUV condensing mirror.

  When the laser device irradiates the target with pulsed laser light, the target may reflect a part of the pulsed laser light. The pulsed laser light reflected by the target can travel along the same optical path as the EUV light. In order to suppress the pulse laser beam reflected by the target from being output to an external exposure apparatus, a plurality of grooves may be formed on the reflection surface of the EUV collector mirror. The plurality of grooves may function as a diffraction grating that diffracts the pulse laser beam. When the depth of the plurality of grooves is ¼ of the wavelength of the pulse laser beam, the 0th-order diffracted light of the pulse laser beam becomes weak, and the pulse laser beam is prevented from being output to an external exposure apparatus. Can be done.

  However, depending on the incident angle of the pulse laser beam with respect to the reflection surface of the EUV collector mirror, the 0th-order diffracted light may not be sufficiently weakened.

  According to one aspect of the present disclosure, the reflective surface of the EUV collector mirror includes a first region and a second region farther from the center of the EUV collector mirror than the first region, and the EUV collector mirror The plurality of grooves formed in the reflective surface may have a first depth in the first region and a second depth larger than the first depth in the second region.

  According to this aspect, since the 0th-order diffracted light of the pulse laser light is weakened according to the incident angle of the pulse laser light with respect to the reflection surface of the EUV collector mirror, the pulse laser light may be output to an external exposure apparatus. Can be suppressed.

2. 2. General Description of EUV Light Generation System 2.1 Configuration FIG. 1 schematically shows a configuration of an exemplary LPP type EUV light generation system. The EUV light generation apparatus 1 may be used together with at least one laser apparatus 3. In the present application, a system including the EUV light generation apparatus 1 and the laser apparatus 3 is referred to as an EUV light generation system 11. As shown in FIG. 1 and described in detail below, the EUV light generation apparatus 1 may include a chamber 2 and a target generation unit 26. The chamber 2 may be sealable. The target generation unit 26 may be attached so as to penetrate the wall of the chamber 2, for example. The material of the target substance output from the target generation unit 26 may include, but is not limited to, tin, terbium, gadolinium, lithium, xenon, or a combination of any two or more thereof.

  The wall of the chamber 2 may be provided with at least one through hole. A window 21 may be provided in the through hole, and the pulse laser beam 32 output from the laser device 3 may pass through the window 21. In the chamber 2, for example, an EUV collector mirror 23 having a spheroidal reflecting surface may be disposed. The EUV collector mirror 23 as a mirror device may have first and second focal points. On the surface of the EUV collector mirror 23, for example, a multilayer reflective film in which molybdenum and silicon are alternately laminated may be formed. The EUV collector mirror 23 is preferably arranged such that, for example, the first focal point thereof is located in the plasma generation region 25 and the second focal point thereof is located at the intermediate focal point (IF) 292. A through hole 24 may be provided at the center of the EUV collector mirror 23, and the pulse laser beam 33 may pass through the through hole 24.

  The EUV light generation apparatus 1 may include an EUV light generation control unit 5, a target sensor 4, and the like. The target sensor 4 may have an imaging function and may be configured to detect the presence, trajectory, position, speed, and the like of the target 27.

  Further, the EUV light generation apparatus 1 may include a connection unit 29 that allows the inside of the chamber 2 and the inside of the exposure apparatus 6 to communicate with each other. A wall 291 in which an aperture is formed may be provided inside the connection portion 29. The wall 291 may be arranged such that its aperture is located at the second focal position of the EUV collector mirror 23.

  Furthermore, the EUV light generation apparatus 1 may include a laser beam traveling direction control unit 34, a laser beam focusing mirror 22, a target recovery unit 28 for recovering the target 27, and the like. The laser beam traveling direction control unit 34 may include an optical element for defining the traveling direction of the laser beam and an actuator for adjusting the position, posture, and the like of the optical element.

2.2 Operation Referring to FIG. 1, the pulsed laser beam 31 output from the laser device 3 passes through the window 21 as the pulsed laser beam 32 through the laser beam traveling direction control unit 34 and enters the chamber 2. May be. The pulse laser beam 32 may travel through the chamber 2 along at least one laser beam path, be reflected by the laser beam collector mirror 22, and be irradiated to the at least one target 27 as the pulse laser beam 33.

  The target generation unit 26 may be configured to output the target 27 toward the plasma generation region 25 inside the chamber 2. The target 27 may be irradiated with at least one pulse included in the pulse laser beam 33. The target 27 irradiated with the pulsed laser light is turned into plasma, and radiation light 251 can be emitted from the plasma. The EUV collector mirror 23 may reflect the EUV light included in the emitted light 251 with a higher reflectance than light in other wavelength ranges. The reflected light 252 including the EUV light reflected by the EUV collector mirror 23 may be condensed at the intermediate condensing point 292 and output to the exposure apparatus 6. A single target 27 may be irradiated with a plurality of pulses included in the pulse laser beam 33.

  The EUV light generation controller 5 may be configured to control the entire EUV light generation system 11. The EUV light generation controller 5 may be configured to process image data of the target 27 imaged by the target sensor 4. Further, the EUV light generation control unit 5 may be configured to control the timing at which the target 27 is output, the output direction of the target 27, and the like, for example. Further, the EUV light generation control unit 5 may be configured to control, for example, the oscillation timing of the laser device 3, the traveling direction of the pulse laser light 32, the condensing position of the pulse laser light 33, and the like. The various controls described above are merely examples, and other controls may be added as necessary.

3. EUV Light Generation System Including EUV Condensing Mirror Formed with Diffraction Grating 3.1 Configuration FIG. 2 is a partial cross-sectional view showing the configuration of the EUV light generation system 11 according to the first embodiment. As shown in FIG. 2, a condensing optical system 22 a, an EUV collector mirror 23, a target recovery unit 28, an EUV collector mirror holder 41, and plates 42 and 43 are provided inside the chamber 2. May be. A target generator 26 may be attached to the chamber 2. The target generation unit 26 may include a target control unit 52, a pressure regulator 53, a shaker 59, and a reservoir 61.

  A laser beam traveling direction control unit 34a, an EUV light generation control unit 5, and a laser device 3 may be provided outside the chamber 2. The laser beam traveling direction control unit 34a may include high reflection mirrors 341 and 342. The high reflection mirror 341 may be supported by the holder 343. The high reflection mirror 342 may be supported by the holder 344.

  The plate 42 may be fixed to the chamber 2. A plate 43 may be fixed to the plate 42. The EUV collector mirror 23 may be fixed to the plate 42 via the EUV collector mirror holder 41.

  The condensing optical system 22a may include an off-axis paraboloid mirror 221 and a plane mirror 222. The off-axis parabolic mirror 221 may be supported by the holder 223. The plane mirror 222 may be supported by the holder 224. The holders 223 and 224 may be fixed to the plate 43. The positions and postures of these mirrors may be maintained so that the pulsed laser light 33 reflected by the off-axis paraboloid mirror 221 and the plane mirror 222 is condensed in the plasma generation region 25.

  The reservoir 61 of the target generator 26 may store the target material in a melted state using a heater (not shown). A part of the reservoir 61 may penetrate the through-hole 20 formed in the wall surface of the chamber 2, and the tip of the reservoir 61 may be located inside the chamber 2. An opening 62 may be formed at the tip of the reservoir 61. The flange portion 61 a of the reservoir 61 may be tightly fixed to the wall surface of the chamber 2 around the through hole 20.

3.2 Operation The target generation unit 26 may output the molten target material as the droplet-shaped target 27 toward the plasma generation region 25 in the chamber 2 through the opening 62. The droplet-shaped target 27 may have a spherical shape depending on the surface tension. The target recovery unit 28 may be disposed on an extension of the trajectory of the target 27 and recover the target 27 that has passed through the plasma generation region 25.

  The pulse laser beam 31 output by the laser device 3 may be guided to the condensing optical system 22a as the pulse laser beam 32 by the laser beam traveling direction control unit 34a. The pulsed laser light 32 may enter the chamber 2 through the window 21 and may be condensed on the plasma generation region 25 as the pulsed laser light 33 by the condensing optical system 22a.

  The EUV light generation control unit 5 controls the target generation unit 26 and the laser apparatus 3 so that the pulse laser beam 33 is focused on the plasma generation region 25 at the timing when the target 27 reaches the plasma generation region 25. Good. Thereby, the target 27 may be irradiated with the pulsed laser light 33 and the target 27 may be turned into plasma. Radiation light 251 including EUV light may be emitted from the plasma. Further, when the target 27 is irradiated with the pulse laser beam 33, a part of the pulse laser beam 33 can be reflected as the pulse laser beam 35 by the target 27. The pulsed laser light 35 travels in multiple directions including direction components opposite to the traveling direction of the pulsed laser light 33, and at least a part of the pulsed laser light 35 can enter the EUV collector mirror 23.

  The EUV light included in the radiation light 251 may be reflected by the EUV collector mirror 23, and the reflected light 252 including this EUV light may be output toward the exposure apparatus 6 shown in FIG. The pulse laser beam 35 can be reflected as the pulse laser beam 36 by the EUV collector mirror 23. In order to suppress the output of the pulse laser beam 36 to the exposure apparatus 6, the EUV collector mirror 23 may have a configuration described below.

3.3 EUV collector mirror with diffraction grating formed FIG. 3A is a plan view of the EUV collector mirror 23 used in the first embodiment, and FIG. 3B is an EUV collector mirror 23 shown in FIG. 3A. It is sectional drawing in the IIIB-IIIB line | wire. 4 shows an enlarged part of a cross section of the EUV collector mirror 23 shown in FIG. 3B. In FIG. 4, hatching indicating a cross section of the EUV collector mirror 23 is omitted. The EUV collector mirror 23 may include a substrate part 70 and a multilayer reflective film 80 located on a concave part formed on one surface of the substrate part 70. The surface 85 of the multilayer reflective film 80 may have a plurality of grooves 84. As shown in FIG. 3A, the plurality of grooves 84 may be concentric. As shown in FIG. 4, the cross section of the plurality of grooves 84 may be rectangular.

FIG. 5 shows an enlarged part of a section of the EUV collector mirror 23 shown in FIG. In FIG. 5, hatching indicating a cross section of the EUV collector mirror 23 is omitted. The multilayer reflective film 80 may include a first stacked unit 80a that covers one surface of the substrate unit 70, and a second stacked unit 80b that partially covers the surface of the first stacked unit 80a. The surface 85 of the multilayer reflective film 80 may include the surface of the second stacked unit 80b and the portion of the surface of the first stacked unit 80a that is not covered by the second stacked unit 80b. On the surface 85 of the multilayer reflective film 80, the surface of the first stacked portion 80a is recessed with respect to the surface of the second stacked portion 80b, so that the recessed portion becomes the groove 84. ing. Groove depth d ₁ may correspond to the thickness of the second laminate section 80b. The groove pitch p may be about twice as large as the groove width f, and may be, for example, 100 μm or more and 5000 μm or less. The groove pitch p may be preferably 500 μm or more and 2000 μm or less.

  As shown in FIG. 4, the emitted light 251 and the pulsed laser light 35 reflected by the target 27 can be incident on the surface 85 of the multilayer reflective film 80. The emitted light 251 may include EUV light having a wavelength of 13.5 nm. The pulse laser beam 35 may include infrared light having a wavelength of 10.6 μm. As shown in FIG. 5, the pulse laser beam 35 includes a pulse laser beam 35a incident on the surface of the first stacked unit 80a and a pulse laser beam 35b incident on the surface of the second stacked unit 80b. But you can.

  When the pulsed laser light 35 is reflected by the surface 85 of the multilayer reflective film 80, the surface 85 of the multilayer reflective film 80 in which the plurality of grooves 84 are formed can function as a diffraction grating. That is, the pulsed laser light 35a may be diffracted by the surface 85 of the multilayer reflective film 80 and reflected by a plurality of direction components including the first direction component 37a and the second direction component 38a. The pulsed laser light 35b may be diffracted by the surface 85 of the multilayer reflective film 80 and reflected by a plurality of direction components including the first direction component 37b and the second direction component 38b. Note that diffraction can refer to a phenomenon in which when a wave is blocked by an obstacle, the wave spreads and propagates behind the obstacle. This diffraction can also occur when light is reflected on a reflective surface in which a plurality of grooves 84 are formed, such as the surface 85 of the multilayer reflective film 80.

  The reflection angles of the first direction component 37a and the first direction component 37b may be equal to the incident angles of the pulse laser beam 35a and the pulse laser beam 35b. The reflection angles of the second direction component 38a and the second direction component 38b may be different from the incident angles of the pulse laser beam 35a and the pulse laser beam 35b.

  In FIG. 5, pulsed laser beams 35a, 35b, 37a, 37b, 38a and 38b are indicated by wavy lines. These wavy lines conceptually show the respective phases of the pulsed laser light. The pulse laser beam 35a and the pulse laser beam 35b may have the same phase.

When the incident angles of the pulse laser beam 35a and the pulse laser beam 35b are 0 °, the optical path length of the pulse laser beam 35a and the first direction component 37a, and the optical path length of the pulse laser beam 35b and the first direction component 37b, A difference corresponding to twice the groove depth d ₁ may occur. This difference in optical path length may correspond to a half of the wavelength λ when the groove depth d ₁ is a quarter of the wavelength λ of the pulsed laser light 35. Thereby, the phase of the first direction component 37a and the phase of the first direction component 37b can be opposite to each other. Accordingly, the first direction component 37a and the first direction component 37b may interfere with each other and weaken each other. The first direction component 37a and the first direction component 37b having reflection angles that are equal to the incident angles of the pulse laser beam 35a and the pulse laser beam 35b can be referred to as zero-order diffracted light. It is desirable to set the groove depth d ₁ so that these zero-order diffracted lights weaken each other. That is, when the incident angles of the pulse laser beam 35a and the pulse laser beam 35b are 0 °, it is desirable that d ₁ = λ / 4.

  On the other hand, the difference between the optical path length of the pulse laser beam 35a and the second direction component 38a and the optical path length of the pulse laser beam 35b and the second direction component 38b is the second direction component 38a and the second direction component 38b. Depending on the reflection angle. When the second direction component 38a and the second direction component 38b have a specific reflection angle, the phase of the second direction component 38a and the phase of the second direction component 38b can match. Thereby, the second direction component 38a and the second direction component 38b having specific reflection angles different from the incident angles of the pulse laser beam 35a and the pulse laser beam 35b may be strengthened to each other. A plurality of such specific reflection angles exist discretely, and interference fringes may be formed by the second direction component 38a and the second direction component 38b having such specific reflection angles. Among such specific reflection angles, there are two reflection angles closest to the reflection angle of the 0th-order diffracted light, and the direction components having the respective reflection angles can be referred to as −1st-order diffracted light and + 1st-order diffracted light. In FIG. 4, the −1st order diffracted light and the + 1st order diffracted light are shown as pulsed laser light 36. It is desirable that the −1st order diffracted light and the + 1st order diffracted light have stronger light intensity than the 0th order diffracted light.

  On the other hand, the surface 85 of the multilayer reflective film 80 may not function as a diffraction grating when reflecting the emitted light 251 having a very small wavelength with respect to the groove width f of the plurality of grooves 84. That is, as shown in FIG. 4, the incident angle of the emitted light 251 and the reflected angle of the reflected light 252 can be the same. As long as the incident angle of the radiated light 251 and the reflected angle of the reflected light 252 are the same, the multilayer reflective film 80 collects the reflected light 252 at the intermediate condensing point 292 as shown in FIGS. 2 and 3B. obtain. On the other hand, as shown in FIG. 2, the pulsed laser light 36 that has become −1st order diffracted light and + 1st order diffracted light by the surface 85 of the multilayer reflective film 80 can travel in a direction different from the direction toward the intermediate condensing point 292. . Thereby, the reflected light 252 passes through the aperture of the wall 291 and is output to the exposure apparatus 6, and the pulsed laser light 36 hits the wall 291 and can be prevented from passing through the exposure apparatus 6.

3.4 Relationship Between Distance from Center of Substrate Part and Groove Depth As shown in FIG. 3B, the surface of the multilayer reflective film 80 is closer to the first region 81 and the center of the substrate unit 70 than the first region 81. And a distant second region 82. The incident angle of the pulse laser beam 35 incident on the second region 82 can be larger than the incident angle of the pulse laser beam 35 incident on the first region 81. The situation in which the incident angle is different between the first region 81 and the second region 82 may be remarkable when the EUV collector mirror 23 has a spheroidal reflection surface, for example, and other shapes of reflection surfaces. May be the same. Here, the center of the substrate or the EUV collector mirror may be a position where the axis when the reflecting surface is a rotationally symmetric surface intersects the surface of the substrate or the EUV collector mirror. Alternatively, on the surface of the EUV collector mirror, it may be a position on the substrate or the EUV collector mirror corresponding to the position where the incident angle of the pulse laser beam incident on the EUV collector mirror is the smallest.

FIG. 6 shows optical paths of the first direction components 37a and 37b when the incident angle of the pulse laser beam 35 is larger than that shown in FIG. In FIG. 6, hatching indicating a cross section of the EUV collector mirror 23 is omitted. Groove depth d ₂ may correspond to the thickness of the second laminate section 80b. The pulse laser beam 35 may include a pulse laser beam 35a incident on the surface of the first stacked unit 80a and a pulse laser beam 35b incident on the surface of the second stacked unit 80b. When the pulse laser beam 35a and the pulse laser beam 35b are incident on the surface 85 of the multilayer reflective film 80 at an incident angle θ, the first direction component 37a and the first direction component 37b constituting the 0th-order diffracted light have an incident angle θ May have a reflection angle equal to

  In FIG. 6, the optical path of the virtual pulse laser beam 35c and the virtual first direction component 37c obtained by shifting the optical path of the pulse laser beam 35b and the first direction component 37b in the direction along the surface 85 of the multilayer reflective film 80. It is shown. It is assumed that the optical path lengths of the virtual pulse laser beam 35c and the virtual first direction component 37c are equal to the optical path lengths of the pulse laser beam 35b and the first direction component 37b.

As shown in FIG. 6, there is a groove depth between the optical path length of the pulse laser beam 35a and the first direction component 37a and the optical path length of the virtual pulse laser beam 35c and the virtual first direction component 37c. A difference corresponding to twice the value obtained by multiplying the value d ₂ by cos θ may occur. In order to make the phase of the first direction component 37a and the phase of the virtual first direction component 37c opposite to each other, the difference in the optical path length is expressed by the following equation: It may be half of the wavelength λ.
2d ₂ cos θ = λ / 2

At this time, the groove depth d ₂ can be calculated as follows.
d ₂ = λ / (4 cos θ)
By groove depth d ₂ is set in this way, 0 can weaken the strength of the diffracted light, pulsed laser beam 36 can be prevented from passing toward the exposure device 6.

FIG. 7 shows a preferable groove depth in the case where the pulse laser beam 35 is a CO ₂ laser beam in relation to the incident angle to the multilayer reflective film 80. The pulsed laser light 35 that is CO ₂ laser light may include infrared light having a wavelength of 10.6 μm. When the incident angle θ of the pulse laser beam 35 is 0 °, the groove depth d may be a value obtained by dividing the wavelength of the pulse laser beam 35 by 4, that is, about 2.65 μm. When the incident angle θ of the pulse laser beam 35 is 30 °, the groove depth d may be a value obtained by dividing the wavelength of the pulse laser beam 35 by 4 cos θ, that is, about 3.06 μm.

  As described above with reference to FIG. 3B, the pulse incident on the second region 82 farther from the center of the substrate unit 70 than the incident angle of the pulse laser beam 35 incident on the first region 81 near the center of the substrate unit 70. The incident angle of the laser beam 35 can be larger. Therefore, it is desirable that the groove depth in the second region 82 far from the center of the substrate part 70 is larger than the groove depth in the first region 81 near the center of the substrate part 70.

  The groove depth may change gently according to the distance from the center of the substrate part 70, or may change stepwise. For example, the groove depth is 2.65 μm in the region where the incident angle of the pulse laser beam 35 is 0 ° or more and less than 7 °, and the groove is formed in the region where the incident angle of the pulse laser beam 35 is 7 ° or more and less than 14 °. The depth may be 2.70 μm. The groove depth is 2.78 μm in the region where the incident angle of the pulse laser beam 35 is 14 ° or more and less than 21 °, and the groove depth is in the region where the incident angle of the pulse laser beam 35 is 21 ° or more and less than 28 °. May be 2.91 μm. In the region where the incident angle of the pulse laser beam 35 is 28 ° or more and 35 ° or less, the groove depth may be 3.11 μm.

Further, the groove depth in each region does not have to be a specific value. Although it depends on how much zero-order light is allowed, it may be set to a value within the range exemplified below.
FIG. 8 shows a preferable range of the groove depth when the pulse laser beam is a CO ₂ laser beam in relation to the incident angle to the multilayer reflective film.
For example, when the diffraction efficiency of the 0th-order light is allowed to 2%, the groove depth may be 2.42 μm or more and 2.88 μm or less in the region where the incident angle of the pulse laser beam 35 is 0 °. . In that case, in the region where the incident angle of the pulse laser beam 35 is 30 °, the groove depth is 2.78 μm or more and 3.34 μm or less, and in the region where the incident angle of the pulse laser beam 35 is 0 °. It may be larger than the groove depth.
Preferably, when the diffraction efficiency of the 0th-order light is allowed to 1%, the groove depth is 2.49 μm or more and 2.81 μm or less in the region where the incident angle of the pulse laser beam 35 is 0 °. Good. In that case, the groove depth may be not less than 2.87 μm and not more than 3.25 μm in a region where the incident angle of the pulse laser beam 35 is 30 °.
More preferably, the groove depth is 2.54 μm or more in the region where the incident angle of the pulse laser beam 35 is 0 ° when the diffraction efficiency of the 0th-order light is allowed to 0.5%. It may be 76 μm or less. In that case, the groove depth may be not less than 2.93 μm and not more than 3.19 μm in a region where the incident angle of the pulse laser beam 35 is 30 °.

3.5 Manufacturing Method FIG. 9 schematically shows a processing apparatus for manufacturing the EUV collector mirror 23 used in the first embodiment. This processing apparatus may include a rotary stage 91, a moving stage 92, a direction adjusting device 93, and an ion milling device 94.

  The rotary stage 91 may support the substrate unit 70 in a rotatable manner. One surface of the substrate unit 70 has a spheroidal shape, and the multilayer reflective film 80 may be formed on the one surface. The substrate unit 70 may be rotatable about the straight line connecting the two focal points of the spheroid by the rotary stage 91.

  The moving stage 92 may support the ion milling device 94 so as to be movable along the rotation axis of the substrate unit 70 by the rotating stage 91. The direction adjusting device 93 may be capable of adjusting the emission direction of the ion beam by the ion milling device 94. The ion milling device 94 may include a mask 95. The mask 95 may have an opening through which the ion beam passes, and may restrict the beam width of the ion beam emitted from the ion milling device 94. The ion milling device 94 may form a groove 84 by removing a part of the multilayer reflective film 80 formed on the one surface of the substrate unit 70 by emitting an ion beam. The width of the opening of the mask 95 may be set according to the groove width f of the groove 84 to be formed.

Here, assuming that the length of the major axis of the ellipse in the spheroid constituting one surface of the substrate portion 70 is 2a and the length of the minor axis is 2b, this spheroid is expressed by the following equation (1). Can be equivalent to a trajectory obtained by rotating the ellipse around the straight line connecting the two focal points of the ellipse.
x ² / a ² + y ² / b ² = 1 Equation 1
Here, the x-axis may correspond to the rotation axis of the substrate unit 70 by the rotation stage 91.

The normal of the ellipse at an arbitrary point (x ₁ , y ₁ ) on the ellipse shown in Expression 1 can be expressed by Expression 2 below.
y = (a ² y ₁ / b ² x ₁ ) x + y ₁ (1−a ² / b ² ) Equation 2
Alternatively, the following formula may be used.
x = (b ² x ₁ / a ² y ₁ ) y + x ₁ (1−b ² / a ² )

Therefore, first, the moving stage 92 may move the ion milling device 94 to the following position along the x axis.
x = x ₁ (1-b ² / a ² )
Next, the direction adjusting device 93 may adjust the direction of emission of the ion beam by the ion milling device 94 to a direction corresponding to the inclination a ² y ₁ / b ² x ₁ of Equation 2.
Then, the ion milling device 94 emits an ion beam while rotating the substrate unit 70 by the rotary stage 91, whereby the groove 84 can be formed in the multilayer reflective film 80.

Furthermore, by performing the same process using the other points (x ₂ , y ₂ ) on the ellipse instead of the above points (x ₁ , y ₁ ), a plurality of concentric circular shapes are formed on the multilayer reflective film 80. A groove 84 may be formed.
The groove depth may be controlled by controlling the intensity of the ion beam, the rotational speed of the rotary stage 91, or both.

4). EUV Condensing Mirror with Reduced Thickness of Second Laminating Section 4.1 Configuration FIG. 10 shows an enlarged part of the cross section of the EUV collector mirror 23 used in the second embodiment. In FIG. 10, hatching indicating a cross section of the EUV collector mirror 23 is omitted. In the second embodiment, the substrate part 70 may have a concave part 70c and a convex part 70d. The multilayer reflective film 80 may include a first stacked unit 80c located in the recess 70c and a second stacked unit 80d positioned in the projecting part 70d.

The surface 85 of the multilayer reflective film 80 may include the surface of the second stacked unit 80d and the surface of the first stacked unit 80c. On the surface 85 of the multilayer reflective film 80, the surface of the first stacked portion 80c is recessed with respect to the surface of the second stacked portion 80d, so that the recessed portion becomes the groove 84. ing. Groove depth d ₃ may be greater than the thickness of the second laminated portion 80d. The thickness of the first stacked unit 80c and the thickness of the second stacked unit 80d may be substantially equal. If the thickness of the first laminated portion 80c and the thickness of the second laminated portion 80d are equal, the groove depth d ₃ may correspond to the step of the recess 70c and the protrusion 70d of the substrate portion 70.

According to the second embodiment, the thickness of the second stacked portion 80d necessary for reflecting the EUV light and the groove depth necessary for the zeroth-order diffracted light to weaken each other when the pulsed laser light 35 is reflected. is a _{d 3,} it can be set separately. That is, the thickness of the second laminate section 80d can be made smaller than the groove depth d _3, can be reduced stacking number of the multilayer reflective film than the first embodiment. For this reason, the number of steps required for forming the multilayer reflective film can be reduced.

4.2 Manufacturing Method FIG. 11 schematically shows a processing apparatus for manufacturing the EUV collector mirror 23 used in the second embodiment. This processing apparatus may include a cutting tool 96 instead of the ion milling apparatus 94 shown in FIG. The rotary stage 91 may rotatably support the substrate unit 70 on which the multilayer reflective film 80 is not formed. The cutting tool 96 may have an extendable cutting blade 97, and the cutting portion 97 may form a recess 70 c in the substrate portion 70.

After the recess 70c is formed in the substrate unit 70, the multilayer reflective film 80 including the first stacked unit 80c and the second stacked unit 80d may be formed.
About another point, it may be the same as that of 1st Embodiment.

5. FIG. 12A is a plan view of an EUV collector mirror 23 used in the third embodiment, and FIG. 12B is an EUV collector shown in FIG. 12A. It is sectional drawing in the XIIB-XIIB line | wire of the optical mirror 23. FIG. The pulse laser beam 33 can be reflected by the target 27 as a multi-directional pulse laser beam 35 including a pulse laser beam 351, a pulse laser beam 352, and a pulse laser beam 353. At this time, the pulse laser that travels toward the second region 82 farther from the center of the substrate unit 70 than the pulse laser beam 351 that travels toward the first region 81 near the center of the substrate unit 70 of the EUV collector mirror 23. The light 352 can have a lower light intensity. Further, the pulse laser beam 353 traveling toward the third region 83 farther from the center of the substrate portion 70 may have a smaller light intensity than the pulse laser beam 352 traveling toward the second region 82. . On the other hand, the radiation light 251 including the EUV light described with reference to FIG. 1 can be emitted from the plasma generation region 25 almost isotropically.

Therefore, in the third region 83, the multilayer reflective film 80 for reflecting the EUV light is formed, but the groove 84 for diffracting the pulsed laser light 353 may not be formed. That is, in the multilayer reflective film 80 of the EUV collector mirror 23, the groove 84 may be formed only in a part of the region including the first region 81 and the second region 82. Even in this case, it is desirable that the groove depth in the second region 82 far from the center of the substrate unit 70 is larger than the groove depth in the first region 81 near the center of the substrate unit 70.
About another point, it may be the same as that of 1st Embodiment.
The region where the groove 84 is not formed is not limited to the third region 83 far from the center of the substrate unit 70, and may be another region.

6). Others In the above-described embodiment, the case where the cross-sectional shape of the groove 84 is rectangular has been described, but the present disclosure is not limited thereto. The cross-sectional shape of the groove may be triangular or other shapes.

  In the above-described embodiment, the case where the plurality of grooves 84 are concentric has been described, but the present disclosure is not limited thereto. The grooves may be formed in a spiral shape or may be formed in a lattice shape.

  In the above-described embodiment, the case where the plurality of grooves 84 are formed in the EUV collector mirror 23 having the spheroidal reflection surface has been described, but the present disclosure is not limited thereto. A groove may be formed in a concave mirror such as a spherical mirror, a parabolic mirror, or a toroidal mirror. Further, when a part of the EUV collector mirror 23 has a concave shape, a plurality of grooves 84 may be formed in the concave shape portion.

  The above description is intended to be illustrative only and not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the embodiments of the present disclosure without departing from the scope of the appended claims.

  Terms used throughout this specification and the appended claims should be construed as "non-limiting" terms. For example, the terms “include” or “included” should be interpreted as “not limited to those described as included”. The term “comprising” should be interpreted as “not limited to what is described as having”. Also, the modifier “one” in the specification and the appended claims should be interpreted to mean “at least one” or “one or more”.

DESCRIPTION OF SYMBOLS 1 ... EUV light generation apparatus, 2 ... Chamber, 3 ... Laser apparatus, 4 ... Target sensor, 5 ... EUV light production | generation control part, 6 ... Exposure apparatus, 11 ... EUV light generation system, 20 ... Through-hole, 21 ... Window, DESCRIPTION OF SYMBOLS 22 ... Laser beam condensing mirror, 22a ... Condensing optical system, 23 ... EUV condensing mirror, 24 ... Through-hole, 25 ... Plasma production | generation area, 26 ... Target production | generation part, 27 ... Target, 28 ... Target collection | recovery part, 29 ... connection part 31, 32, 33 ... pulse laser light, 34, 34a ... laser light traveling direction control part, 35, 35a, 35b ... pulse laser light, 35c ... virtual pulse laser light, 36 ... pulse laser light, 37a , 37b ... first direction component, 37c ... virtual first direction component, 38a, 38b ... second direction component, 41 ... EUV collector mirror holder, 42, 43 ... plate 52 ... Target controller, 53 ... Pressure regulator, 59 ... Vibration device, 61 ... Reservoir, 61a ... Flange part, 62 ... Opening, 70 ... Substrate part, 70c ... Recess, 70d ... Protrusion, 80 ... Multilayer reflective film , 80a... First stacked portion, 80b... Second stacked portion, 80c... First stacked portion, 80d... Second stacked portion, 81... First region, 82. , 84 ... groove, 85 ... surface, 91 ... rotary stage, 92 ... moving stage, 93 ... direction adjusting device, 94 ... ion milling device, 95 ... mask, 96 ... cutting tool, 97 ... cutting blade, 221 ... off-axis release Object mirror, 222 ... Planar mirror, 223, 224 ... Holder, 251 ... Radiated light, 252 ... Reflected light, 291 ... Wall, 292 ... Intermediate focusing point, 341, 342 ... High reflection mirror, 343, 344 ... Holder, 351, 352, 353 Pulsed laser _{light, d, d 1, d 2} , d 3 ... groove depth, f ... groove width, p ... groove pitch

Claims (7)

A substrate part having a concave part formed on one surface;
A multilayer reflective film that is located in the concave portion and has a plurality of grooves formed on the surface;
Including
The mirror device, wherein the plurality of grooves are formed such that the depth in the second region farther from the center of the concave surface portion than the first region is larger than the depth in the first region. The concave surface portion has a concave portion and a convex portion,
2. The mirror device according to claim 1, wherein the multilayer reflective film includes a first stacked portion positioned in the concave portion and a second stacked portion positioned in the convex portion.   2. The mirror device according to claim 1, wherein the multilayer reflective film includes a first stacked portion that covers the concave surface portion and a second stacked portion that partially covers the surface of the first stacked portion.   The mirror device according to claim 1, wherein the concave surface portion has a spheroid shape.   The mirror device according to claim 1, wherein the plurality of grooves are arranged substantially concentrically. A chamber provided with a through hole;
A target generator configured to output a target into the chamber;
A laser focusing optical system configured to introduce pulsed laser light into the chamber through the through hole;
A mirror device for collecting extreme ultraviolet light generated in the chamber;
With
The mirror device is
A substrate part having a concave part formed on one surface;
A multilayer reflective film that is located in the concave portion and has a plurality of grooves formed on the surface;
Including
The extreme ultraviolet light generation device, wherein the plurality of grooves are formed so that a depth in a second region farther from the center of the concave portion than the first region is larger than a depth in the first region. A laser device for generating pulsed laser light;
A chamber provided with a through hole;
A target generator configured to output a target into the chamber;
A laser focusing optical system configured to introduce the pulsed laser light into the chamber through the through hole;
A mirror device for collecting extreme ultraviolet light generated in the chamber;
With
The mirror device is
A substrate part having a concave part formed on one surface;
A multilayer reflective film that is located in the concave portion and has a plurality of grooves formed on the surface;
Including

The extreme ultraviolet light generation system, wherein the plurality of grooves are formed so that a depth in a second region farther from the center of the concave portion than the first region is larger than a depth in the first region.

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