JP2005098930A - Multilayer-film reflector, method for reconditioning it and exposure system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer-film reflector where a multilayer film can be removed, without affecting the surface of a substrate, when the making of the multilayer-film reflector is done over and the like. <P>SOLUTION: The surface of a silicon substrate 2 is worked into a form of a paraboloid of revolution with high precision. On the surface of the substrate 2, a film of a primary coat layer 1 is formed, and an Mo/Si multilayer film 3 is formed on the layer 1; and the area of a region where the Mo/Si multilayer film 3 is formed is smaller than that of the region where a silver thin-film 1 is formed, and a part of it is exposed from the Mo/Si multilayer film 3. A polyimide tape 4, coated with a tackifier, adheres to the exposed part of the primary coat layer 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a multilayer mirror, a reproducing method thereof, and an exposure apparatus. In particular, the present invention relates to a multilayer film reflecting mirror or the like that can peel off a multilayer film formed on a substrate surface without physically damaging the surface of the substrate.

  With further progress in miniaturization of semiconductor integrated circuit elements, development of projection lithography using soft X-rays having a wavelength of about 11 to 14 nm instead of ultraviolet rays has been advanced (see Non-Patent Document 1). This technique is also recently called EUV lithography (Extreme Ultraviolet reduced projection exposure). This EUV lithography is expected as a lithography technique having a resolving power of 50 nm or less, which cannot be realized by conventional optical lithography (wavelength of about 190 nm or more).

  In this soft X-ray wavelength band, there is no transparent substance, and the refractive index of the substance is very close to 1, so that a conventional optical element utilizing refraction cannot be used. Instead, a grazing incidence mirror that uses total reflection, or a multilayer film reflector that achieves a high reflectivity by superimposing a large number of reflected light by matching the phase of weak reflected light at the interface is used. Is done.

  In such a multilayer-film reflective mirror, the material suitable for obtaining a high reflectance varies depending on the wavelength band of incident light. For example, in the wavelength band near 13.5 nm, when a Mo / Si multilayer film in which molybdenum (Mo) layers and silicon (Si) layers are alternately stacked is used, a reflectance of 67.5% can be obtained at normal incidence. it can. In addition, in the wavelength band near 11.3 nm, when a Mo / Be multilayer film in which Mo layers and beryllium (Be) layers are alternately stacked is used, a reflectance of 70.2% can be obtained at normal incidence (non-reflection). Patent Document 2).

  In EUV lithography, such a multilayer mirror is used to construct an illumination optical system that illuminates a mask on which a pattern is formed and a projection optical system that projects a pattern on the mask on a resist-coated wafer. used. As EUV light sources in EUV lithography, there are a high repetition laser plasma light source and a discharge plasma light source. In these light sources, scattered particles such as light source plasma and ions generated around the light source plasma are scattered around. Since the ions generated by the light source plasma have energy of several tens eV to several thousand eV, when the multilayer reflector as described above is arranged around the light source plasma, the surface of the reflector is caused by sputtering. The multilayer film is scraped off. In the case of a discharge plasma light source, the electrode portion of the light source is eroded by the plasma, and the electrode material constituting the electrode portion is scattered. Such an electrode substance adheres to the surface of the multilayer film of the multilayer film reflecting mirror. As described above, if the multilayer film is scraped off or foreign matter adheres to the surface of the multilayer film, the reflectance of the multilayer film mirror decreases, so that the contamination of the multilayer film surface caused by such a light source is reduced. (See, for example, Patent Document 1).

  On the other hand, since the multilayer film constituting the projection optical system is isolated from the light source plasma by a filter or a pinhole, contamination of the multilayer film surface due to the light source as described above does not occur. However, during exposure, the surface of the multilayer film is irradiated with EUV light, so organic residues (eg, exhaust system oil) drifting in the vicinity of the multilayer film mirror are decomposed by the EUV light, and the surface of the multilayer film is carbonized. As a result of contamination (carbon contamination) adhering or oxidation of the multilayer film surface, the multilayer film surface is contaminated, resulting in a problem that the reflectance is lowered. In order to solve this problem, a method has been proposed in which ethanol is introduced into the atmosphere of the multilayer-film reflective mirror to reduce the decrease in reflectance (see, for example, Non-Patent Document 3 and Non-Patent Document 4).

Japanese Patent Laid-Open No. 08-321395 Daniel A. Tichenor, 21 others, "Recent results in the development of an integrated EUVL laboratory tool", "Proceedings of SPIE), (USA), SPIE, The International Society for Optical Engineering, May 1995, Vol. 2437, p. 292 Claude Montcalm, 5 others, "Multilayer reflective coatings for extreme-ultraviolet lithography", "Proceedings of SPIE", (USA) SPIE (The International Society for Optical Engineering), June 1998, 3331, p. 42 Hans Meiling, three others, "Progress of EUVL alpha tool", "Proceedings of SPIE", (USA), Kokusai Kogyo SPIE, The International Society for Optical Engineering, August 2001, 4343, p. 38 LE Klebanoff, “First Environmental data from Engineering Test Stand”, “Second Annual International Workshop on EWV Lithography (2ndAnnual International Workshop on EUV lithography) "," International SEMATECH ", October 2000

  In EUV lithography, one of the major issues is to process the substrate of the reflecting mirror constituting the optical system with high accuracy. And it cannot be avoided that the multilayer film formed on such a reflector substrate has a limited life due to surface contamination as described above.

  In EUV lithography, the multilayer mirror is disposed in a vacuum chamber, but the surface of the multilayer film is irradiated with EUV light having a large energy, so that the chemical reaction is very likely to occur on the surface of the multilayer film. ing. Therefore, it has been reported that when EUV light is irradiated in a state where an organic substance containing a small amount of carbon remains in the vacuum chamber, the organic substance is decomposed and carbon contamination (carbon contamination) adheres to the surface of the multilayer film. Yes. Since this carbon contamination absorbs EUV light, the reflectance of the multilayer mirror is lowered. In order to prevent such adhesion of carbon contamination, a method has also been proposed in which oxygen is introduced into a vacuum chamber, reacted with an organic substance containing carbon in the vacuum chamber, and removed as carbon dioxide. However, according to this method, the adhesion of carbon to the surface of the multilayer film is suppressed, but the surface of the multilayer film is oxidized, which may cause a decrease in reflectance. In general, it is difficult to recover the reflectance of the multilayer film, which has been lowered by oxidation of the surface.

  Some multilayer reflectors used in the light source section of EUV lithography are placed in a more severe use environment. Plasma is used in a light source part of EUV lithography. There are two types of plasma: discharge plasma that generates plasma by discharge between electrodes, and laser plasma that condenses and irradiates a target material with laser light, but the generated plasma itself is almost the same. Is. Since plasma is a mass of ionized ions and molecules, not only EUV light is emitted from the plasma, but also ions are emitted at high speed.

In order to use EUV light radiated from plasma for EUV lithography, it is necessary to collect EUV light into a parallel light beam or a condensed light beam. A multilayer film reflecting mirror (condensing mirror) having an object shape is arranged. In such a collector mirror, ions fly from the light source plasma at a high speed, and the reflectance is lowered because the surface of the multilayer film is sputtered or deposited on the surface. For this reason, it is necessary to replace | exchange the condensing mirror in which the reflectance fell suitably.
A method for reducing or removing the flying material from the light source plasma has been studied. However, in the light source used for EUV lithography, since the repetition frequency of plasma generation reaches up to 10 kHz, the amount of flying substances becomes enormous. In addition, since the allowable reduction in reflectance for the multilayer mirror is up to about 10%, it is considered almost impossible to realize a multilayer mirror having a semi-permanent lifetime.

As described above, since the multilayer reflector used in EUV lithography has a finite lifetime, the multilayer reflector that has reached the end of its life needs to be removed and replaced with a new reflector. At this time, if the damaged multilayer film can be removed without affecting the surface of the substrate, the original substrate can be reused. A mirror can be made. However, in a conventional multilayer reflector in which a Mo / Si multilayer film is directly formed on a substrate such as quartz, the multilayer film cannot be removed with an acid or the like. For this reason, it is necessary to remove the multilayer film by dry etching using argon DC plasma or the like, but in this case, the quartz substrate is also damaged, so that the multilayer film is not affected without affecting the substrate surface. It was difficult to remove. As described above, in the conventional multilayer-film reflective mirror, the substrate could not be reused. Therefore, when a new multilayer-film reflective mirror was manufactured, it was necessary to start with a new substrate. As described above, since the substrate surface needs to be processed with high accuracy, it takes a lot of time and labor to produce a new multilayer-film reflective mirror.
In view of the above points, an object of the present invention is to provide a multilayer reflector that can remove the multilayer without affecting the substrate surface when the multilayer reflector is remade.

The multilayer-film reflective mirror of the present invention comprises a substrate, a substance that can be removed or peeled off by an acid, a base layer formed on the surface of the substrate, and a reflective multilayer film formed on the base layer It is characterized by comprising.
According to the present invention, since the multilayer film can be removed without deteriorating the shape accuracy of the substrate surface by removing the underlayer using acid, the reflector substrate can be reused. Become. Note that a material that can be removed by water or an organic solvent may be used as the material of the underlayer.

In the multilayer mirror described above, the base layer is preferably silver or aluminum.
In this case, since the base layer made of silver or aluminum can be removed with an acid, the multilayer film can be easily removed, and the substrate can be easily reused.

In the above multilayer mirror, the thickness of the underlayer is preferably 100 nm or less.
When silver or aluminum is formed, island-like growth occurs on the film formation surface and the surface roughness is deteriorated. The deterioration of the surface roughness tends to increase as the film thickness of silver or aluminum increases. For this reason, by setting the film thickness of the underlayer to 100 nm or less, an increase in surface roughness can be suppressed and the reflectance of the multilayer film formed on the underlayer can be prevented from decreasing.

In the multilayer-film reflective mirror of the present invention, the surface of the base layer may be smoothed so that the surface roughness is 0.5 nm RMS or less.
In the above-mentioned multilayer-film reflective mirror, as the smoothing process, a process of forming a silicon film on the surface of the underlayer or a process of coating a resin on the surface can be performed.
By forming a silicon layer on the surface of the underlayer by ion beam sputtering, the surface roughness (particularly the surface roughness with a waviness period of 100 nm or less) is improved. As described above, when silver or aluminum is used for the underlayer, island-like growth occurs during film formation and the surface roughness deteriorates. Therefore, by forming silicon on the surface of the underlayer, the surface roughness is increased. To reduce. By forming a multilayer film on the silicon layer, it is possible to prevent a decrease in reflectance due to deterioration of the shape accuracy of the multilayer film surface.
In addition, when a resin dissolved in a suitable solvent is applied to the surface of the underlayer, the surface of the resin becomes smooth due to the surface tension of the resin solution regardless of the fine irregularities on the surface of the underlayer. Therefore, similarly to the case described above, by forming a multilayer film on this resin layer, it is possible to prevent a decrease in reflectance due to deterioration of the shape accuracy of the multilayer film surface.

In the multilayer mirror described above, the smoothing process may be a process of irradiating the surface of the underlayer with an ion beam to remove irregularities on the surface of the underlayer.
In this case, the surface roughness of the underlayer can be reduced by removing the irregularities on the surface of the underlayer by irradiating the ion beam. By forming a multilayer film on the base layer with the reduced surface roughness, it is possible to prevent a decrease in reflectivity due to deterioration of the shape accuracy of the multilayer film surface.

In the multilayer-film reflective mirror of the present invention, the film-forming area of the reflective multilayer film is smaller than the base layer, the base layer is not completely covered by the reflective multilayer film, and a part of the base layer is exposed. It is preferable.
According to the present invention, since a part of the underlayer is exposed, it is easy to peel off the multilayer film. For example, when a silver thin film is used as the underlayer, it is easy to remove the underlayer and the multilayer film from the exposed portion of the silver thin film with a nitric acid solution or the like.

In the multilayer reflector described above, it is preferable that a part of the exposed underlayer is covered with an underlayer protection means that can be easily removed.
In this case, since the exposed underlayer is covered, it is possible to prevent the surface of the underlayer from being contaminated or oxidized. Furthermore, the base layer protection means can easily remove the multilayer film by exposing the base layer when the multilayer film is peeled off.

  The method for regenerating a multilayer-film reflective mirror of the present invention comprises a substrate, a material that can be removed or peeled off by an acid, an underlayer formed on the surface of the substrate, and an overlayer formed on the underlayer A method of regenerating a multilayer reflector comprising: a reflective multilayer film, wherein the substrate surface is dissolved and removed, and the reflective multilayer film is peeled off together with the substrate layer, thereby removing the substrate surface. The reflective multilayer film is removed from the substrate, a base layer is formed again on the substrate surface, and a reflective multilayer film is formed on the base layer.

  An exposure apparatus according to the present invention is an exposure apparatus that selectively irradiates an energy beam onto a sensitive substrate to form a pattern, and includes an optical system including a multilayer film reflecting mirror that reflects the energy beam. The film reflecting mirror includes a substrate, a base layer formed on the surface of the substrate made of a substance that can be removed or peeled off by an acid, and a reflective multilayer film formed on the base layer. It is characterized by doing.

  According to the present invention, it is possible to remove the multilayer film without deteriorating the shape accuracy of the substrate surface by removing the underlayer using acid. As a result, the reflector substrate can be reused, and the multilayer reflector in EUV lithography can be easily replaced.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a state in which a multilayer reflector according to an embodiment of the present invention is installed in a light source unit of an EUV exposure apparatus.
The multilayer-film reflective mirror 10 of this embodiment is used as a light source unit in EUV lithography, and is used as a condensing mirror that reflects EUV light emitted from laser plasma to form a parallel light flux.

FIG. 2 is a view showing the multilayer mirror of FIG. FIG. 2A is a plan view of the reflecting surface side of the multilayer film reflecting mirror, and FIG. 2B is a perspective view of the multilayer film reflecting mirror.
The surface of the silicon substrate 2 of the reflecting mirror 10 is processed with high accuracy into a paraboloid shape. As shown in FIGS. 1 and 2, a silver thin film 1 is formed on the surface of the silicon substrate 2, and a Mo / Si multilayer film 3 is formed on the silver thin film 1. The silver thin film 1 serves as an underlayer for the Mo / Si multilayer 3. For example, the periodic length of the Mo / Si multilayer 3 is 7 nm. The area of the area where the Mo / Si multilayer film 3 is formed is narrower than the area where the silver thin film 1 is formed, and a part of the silver thin film 1 is exposed from the Mo / Si multilayer film 3.

FIG. 3 is a schematic cross-sectional view of the multilayer-film reflective mirror of FIG.
The silver thin film 1 is formed on the substrate 2 by ion beam sputtering, and the thickness of the silver thin film 1 is, for example, 20 nm. The Mo / Si multilayer film 3 is formed on the silver thin film 1 by ion beam sputtering.

  As shown in FIG. 3, in order to prevent the silver thin film 1 from being oxidized when using a multilayer mirror, a polyimide tape in which an adhesive material is applied to the exposed portion of the silver thin film 1 4 (only a part is shown in FIGS. 1 and 2B and omitted in FIG. 2A) is pasted. Further, a shield plate is arranged so that radiation from the plasma 7 does not reach the exposed portion of the silver thin film 1 in order to suppress the thermal load generated in the exposed portion of the silver thin film 1 when EUV light is generated. (Not shown).

  Since the thickness of the silver thin film 1 is as thin as about 20 nm, the surface roughness after the silver thin film 1 is formed is suppressed to 0.5 nm RMS or less. Thereby, the fall of the reflectance by the deterioration of the shape accuracy of the Mo / Si multilayer film 3 is suppressed.

Here, the function of the multilayer-film reflective mirror 10 will be described with reference to FIG.
The multilayer-film reflective mirror 10 is disposed in the vicinity of the laser plasma serving as the EUV light source as described above. Tin fine particles 6 are supplied to the reflective surface side of the multilayer mirror 10. An opening 2a is formed at the center of the multilayer mirror 10, and the excitation pulse laser beam 5 is introduced through the opening 2a. Then, the laser plasma 7 is generated by condensing and emitting the excitation pulse laser beam 5 with the tin fine particles 6 as targets. The EUV light 9a irradiated from the laser plasma 7 is reflected by the multilayer reflector 10 to become a parallel light beam 9b.

  A helium gas (pressure is about 1 Pa) is introduced into a vacuum chamber (not shown) of the exposure apparatus to prevent particles (tin atoms, ions, etc.) from scattering from the plasma 7. In addition, a scattering particle capturing plate 8 is disposed in the vicinity of the reflecting surface of the multilayer reflector 10 to efficiently prevent scattered fine particles scattered by gas molecules from reaching the multilayer reflector 10.

  Although the number of scattered fine particles reaching the surface of the multilayer mirror 10 is greatly reduced by the helium gas and the scattering particle capturing plate 8 as described above, it cannot be completely reduced to zero. For this reason, when used for a long time, tin is gradually deposited on the multilayer film 3 on the surface of the multilayer film reflecting mirror 10, and thus the reflectance of the multilayer film 3 is significantly lowered. A part of the tin deposited on the surface of the multilayer film 3 is oxidized and is very difficult to remove.

Next, a method for reproducing the multilayer-film reflective mirror of this embodiment will be described with reference to FIGS.
FIG. 4 is a diagram showing a method for reproducing a multilayer mirror according to an embodiment of the present invention.
At the stage where the decrease in reflectance due to long-time use as described above becomes unacceptable, the multilayer-film reflective mirror 10 is removed from the exposure apparatus. Then, as shown in FIG. 4, the polyimide tape 4 for protecting the silver thin film 1 is peeled off. Next, with the silver thin film 1 exposed, the multilayer film reflecting mirror 10 is immersed in a container (substrate cleaning tank) 30 in which nitric acid 30a is stretched. Then, the silver thin film 1 is gradually dissolved and removed from the exposed portion in the nitric acid 30 a, and the multilayer film 3 can be completely peeled off from the substrate 2. Finally, a silver thin film and a multilayer film are formed again to reproduce the multilayer film reflecting mirror.

  Here, quartz, which is a substrate material, is not eroded by nitric acid, so that the surface shape and roughness of the substrate 2 are not changed as compared with those before the multilayer film 3 is formed. Therefore, the substrate 2 can be reused as it is.

  According to the present embodiment, the multilayer film having a reduced reflectance is removed from the substrate, and the multilayer film and the silver thin film are simply formed again without processing the substrate surface. Can be played. Therefore, it is not necessary to newly manufacture a reflecting mirror substrate each time a multilayer film reflecting mirror having a lowered reflectivity is replaced. Therefore, the optical element can be replaced quickly and inexpensively.

  In this embodiment, the thickness of the silver thin film 1 is 20 nm. However, if the surface roughness can be suppressed to a level of 0.5 nm RMS or less, it is not necessary to limit the thickness. Even when the surface roughness of the silver thin film 1 is large, the surface roughness of the silver thin film 1 may be reduced by a method such as irradiating the silver thin film 1 with an ion beam after the film formation. A polyimide resin or the like may be applied between the multilayer films 3. When the polyimide resin is loaded, the polyimide resin is dissolved in an appropriate solvent and thinly applied onto the silver thin film 1 by spin coating or the like, thereby smoothing with the surface tension of the polyimide solution.

A silicon film may be formed between the silver thin film and the multilayer film.
FIG. 5 is a cross-sectional view showing a part of a multilayer mirror in which a silicon film is formed between the silver thin film and the multilayer film.
In the multilayer mirror 20 shown in FIG. 5, a silver thin film 25 is formed on the surface of a substrate 22, and a silicon film 21 is formed on the silver thin film 25 by ion beam sputtering. The surface roughness is reduced by the silicon film 21, and the Mo / Si multilayer film 23 formed thereon can achieve a high reflectance.

  As shown in FIG. 5, the deposition area of the silver thin film 25 is larger than that of the silicon film 21 and the Mo / Si multilayer film 23, and the exposed portion of the silver thin film 25 is covered with the polyimide tape 24. Therefore, the multilayer reflector 20 can also be reproduced by the same method as the multilayer reflector 10 described above.

  In this embodiment, a silver thin film (reference numerals 1 and 25) is formed as the base layer of the multilayer film, but the material of the base layer is not limited to this. For example, in addition to the above-mentioned silver, if a metal soluble in an acid such as aluminum, iron, tin, zinc, or nickel is formed as a base layer, the base layer can be easily removed by dipping in the acid. The multilayer film on the ground layer can be removed without damaging the substrate. However, when using aluminum or the like, it is necessary to select the type and concentration of the acid so as not to be passive.

FIG. 6 is a diagram schematically showing an exposure apparatus according to an embodiment of the present invention.
An EUV exposure apparatus 100 shown in FIG. 6 includes an X-ray generator (laser plasma X-ray source) 101. The X-ray generator 101 includes a spherical vacuum vessel 102, and the inside of the vacuum vessel 102 is exhausted by a vacuum pump (not shown).

  A multilayer parabolic mirror 104 is installed on the upper side of the vacuum vessel 102 in the drawing with the reflecting surface 104a facing downward (+ Z direction) in the drawing. As the mirror 104, the multilayer film reflecting mirror of the above-described embodiment is used.

  A lens 106 is arranged on the right side of the vacuum vessel 102 in the drawing, and a laser light source (not shown) is arranged on the right side of the lens 106. This laser light source emits pulsed laser light 105 in the −Y direction. The pulsed laser beam 105 is condensed at the focal position of the multilayer parabolic mirror 104 by the lens 106. A target material 103 (xenon (Xe) or the like) is disposed at this focal position. When the focused pulse laser beam 105 is irradiated onto the target material 103, plasma 107 is generated. The plasma 107 emits soft X-rays (EUV light) 108 having a wavelength band near 13 nm.

  An X-ray filter 109 that cuts visible light is provided below the vacuum container 102. The EUV light 108 is reflected in the + Z direction by the multilayer parabolic mirror 104, passes through the X-ray filter 109, and is guided to the exposure chamber 110. At this time, the spectrum of the visible light band of the EUV light 108 is cut.

  In this embodiment, a laser plasma X-ray source is used as the X-ray generator 101, but a discharge plasma X-ray source can also be used. A discharge plasma X-ray source is one that turns a target material into plasma by pulse high voltage discharge and emits X-rays from this plasma.

  An exposure chamber 110 is installed below the X-ray generator 101 in the figure. An illumination optical system 113 is disposed inside the exposure chamber 110. The illumination optical system 113 is composed of a condenser-type reflection mirror, a fly-eye optical-system reflection mirror, and the like (shown in a simplified manner in the figure), and the EUV light 108 incident from the X-ray generation apparatus 101 is circular. Shape in an arc and irradiate toward the left in the figure.

  A reflecting mirror 115 is disposed on the left side of the illumination optical system 113. The reflecting mirror 115 is a circular concave mirror, and is held vertically (parallel to the Z axis) by a holding member (not shown) so that the reflecting surface 115a faces rightward in the drawing (+ Y direction). An optical path bending reflecting mirror 116 is arranged on the right side of the reflecting mirror 115 in the drawing. Above the optical path bending reflecting mirror 116 in the figure, the reflective mask 111 is disposed horizontally (parallel to the XY plane) so that the reflecting surface 111a faces downward (+ Z direction). The EUV light emitted from the illumination optical system 113 is reflected and collected by the reflecting mirror 115 and then reaches the reflecting surface 111 a of the reflective mask 111 via the optical path bending reflecting mirror 116.

The reflecting mirrors 115 and 116 are made of a substrate made of low thermal expansion glass whose reflecting surface is processed with high accuracy and with little thermal deformation. Similar to the reflective surface of the multilayer parabolic mirror 104 of the X-ray generator 101, the Mo / Si multilayer film in which molybdenum (Mo) and silicon (Si) are alternately stacked is formed on the reflective surface 115a of the reflective mirror 115. Is formed. When X-rays having a wavelength of 10 to 15 nm are used, substances such as molybdenum (Mo), ruthenium (Ru), rhodium (Rh), silicon (Si), beryllium (Be), carbon tetraboride ( A multilayer film combined with a substance such as B ₄ C) may also be used.

  A reflective film made of a multilayer film is also formed on the reflective surface 111 a of the reflective mask 111. A mask pattern corresponding to the pattern to be transferred to the wafer 112 is formed on the reflective film of the reflective mask 111. The reflective mask 111 is attached to a mask stage 117 shown in the upper part of the drawing. The mask stage 117 is movable at least in the Y direction, and the EUV light reflected by the optical path bending reflecting mirror 116 is sequentially scanned on the reflective mask 111.

  A projection optical system 114 and a wafer (a substrate coated with a sensitive resin) 112 are arranged in order from the top below the reflective mask 111 in the drawing. The projection optical system 114 includes a plurality of reflecting mirrors. The wafer 112 is fixed on a wafer stage 118 that can move in the XYZ directions so that the exposure surface 112a faces upward (−Z direction) in the drawing. The EUV light reflected by the reflective mask 111 is reduced to a predetermined reduction magnification (for example, ¼) by the projection optical system 114 to form an image on the wafer 112, and the pattern on the mask 111 is transferred onto the wafer 112. Is done.

  In the present embodiment, the multilayer film reflecting mirror of the above-described embodiment is used as the mirror 104, but is included in the mirrors 115 and 116, the reflective mask 111, the illumination optical system 113, and the projection optical system 114. As the mirror or the like, the multilayer mirror of the above-described embodiment can be used as an arbitrary optical element included in the exposure apparatus 100.

It is a perspective view which shows the state in which the multilayer-film reflective mirror which concerns on one Example of this invention was installed in the light source part of EUV exposure apparatus. It is a figure which shows the multilayer-film reflective mirror of FIG. (A) It is a top view by the side of the reflective surface of a multilayer film reflective mirror. (B) It is a perspective view of a multilayer film reflective mirror. It is typical sectional drawing of the multilayer film reflective mirror of FIG. It is a figure which shows the reproduction | regenerating method of the multilayer-film reflective mirror concerning one Example of this invention. It is sectional drawing which shows a part of multilayer reflective mirror which formed the silicon film between the silver thin film and the multilayer. It is a figure which shows typically the exposure apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

10 Multilayer reflectors 1 Underlayer (silver thin film)
DESCRIPTION OF SYMBOLS 2 Silicon substrate 2a Opening 3 Mo / Si multilayer film 4 Polyimide tape 5 Excitation pulse laser beam 6 Tin fine particle 7 Laser plasma 8 Scattering particle capture plate 9a EUV light 9b Parallel light beam 30 Substrate cleaning tank 30a Nitric acid 100 Exposure apparatus 101 X-ray Generator 102 Vacuum container 103 Target material 104 Multilayer parabolic mirror 105 Pulse laser beam 106 Lens 107 Plasma 108 Soft X-ray 109 Filter 110 Exposure chamber 111 Reflective mask 112 Wafer 113 Illumination optical system 114 Projection optical system 115 Multilayer reflection Mirror 116 Optical path bending reflector 117 Mask stage 118 Wafer stage

Claims (10)

A substrate,
An underlayer formed of a substance that can be removed or peeled off by an acid and formed on the surface of the substrate;
A reflective multilayer film formed on the underlayer;
A multilayer-film reflective mirror comprising:   The multilayer reflector according to claim 1, wherein the underlayer is made of silver or aluminum.   The multilayer mirror according to claim 1 or 2, wherein the underlayer has a thickness of 100 nm or less.   The multilayer-film reflective mirror according to any one of claims 1 to 3, wherein the surface of the underlayer is smoothed so that the surface roughness is 0.5 nm RMS or less.   5. The multilayer mirror according to claim 4, wherein the smoothing process is a process of forming a silicon film on the surface of the underlayer or a process of coating a resin on the surface.   5. The multilayer film reflector according to claim 4, wherein the smoothing process is a process of irradiating the surface of the underlayer with an ion beam to remove irregularities on the surface of the underlayer.   The film formation area of the reflective multilayer film is smaller than the base layer, the base layer is not completely covered with the reflective multilayer film, and a part of the base layer is exposed. The multilayer-film reflective mirror of any one of 1-6.   8. The multilayer film reflecting mirror according to claim 7, wherein a part of the exposed underlayer is covered with an underlayer protecting means that can be easily removed. A substrate,
An underlayer formed of a substance that can be removed or peeled off by an acid and formed on the surface of the substrate;
A reflective multilayer film formed on the underlayer;
A method for regenerating a multilayer reflector comprising:
Dissolving and removing the underlying layer on the substrate surface;
By removing the reflective multilayer film together with the base layer, the reflective multilayer film is removed from the substrate surface,
A base layer is again formed on the surface of the substrate,
A method for reproducing a multilayer reflector, comprising: forming a reflective multilayer film on the underlayer. An exposure apparatus that selectively irradiates a sensitive substrate with energy rays to form a pattern,
An optical system including a multilayer mirror that reflects the energy rays;
The multilayer mirror is
A substrate,
An underlayer formed of a substance that can be removed or peeled off by an acid and formed on the surface of the substrate;
A reflective multilayer film formed on the underlayer;
An exposure apparatus comprising:

Images