JP2006171577A - Optical element and projection exposing device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which exhibits a satisfactory reflection characteristic over a long term in the use under ultraviolet irradiation. <P>SOLUTION: A protective layer 30 protects a multilayer film 20 from an ambient environment by covering the whole surface of a multilayer film 20. The protective layer 30 is formed by using either of (1) an alloy between an oxidation resistant metal and the other metal, (2) an alloy between a catalytically operating metal and the other metal and (3) an alloy among an oxidation resistant metal and a catalytically operating metal and the other metal in accordance with uses and usage conditions of the optical element 40. Thereby, an oxidation reaction is suppressed on the surface of the optical element 40, that is, on the optical surface, or the preparation of a carbon film is suppressed, therefore, the deterioration of reflection characteristic of the optical element is prevented and, moreover, the life of a projection exposing device may be prolonged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reflective optical element used for extreme ultraviolet rays and the like and a projection exposure apparatus using the same.

In recent years, with the miniaturization of semiconductor integrated circuits, in order to improve the resolution of an optical system achieved by the light diffraction limit, extreme ultraviolet rays having a shorter wavelength (11 to 14 nm) are used instead of conventional ultraviolet rays. The exposure technology that has been developed has been developed. This is expected to enable exposure with a pattern size of about 5 to 70 nm. However, since the refractive index of the material in this region is close to 1, it is impossible to use a transmission refraction type optical element as in the past. A reflective optical element is used. The mask used in the projection exposure apparatus is also a normal reflection type optical element from the viewpoint of securing transmittance. At this time, in order to achieve a high reflectance in the optical element, it is common to form a reflective surface by alternately laminating a substance having a high refractive index and a substance having a low refractive index on the substrate in the wavelength range of use. (See Patent Document 1).
Japanese Patent Laid-Open No. 2003-14893

  When the optical element as described above is used under extreme ultraviolet rays in the projection exposure apparatus, the environment is a vacuum, but oxygen, moisture and organic substances cannot be completely excluded from the periphery of the optical element. On the other hand, extreme ultraviolet light has very large energy. At this time, oxygen, moisture, and the substance on the surface of the optical element are irradiated with extreme ultraviolet rays to cause an oxidation reaction. Further, when an organic substance and a substance on the surface of the optical element are irradiated with extreme ultraviolet rays, photochemical vapor deposition (photo CVD) occurs, and a carbon film is generated on the surface of the optical element. Due to these phenomena, the reflection characteristics of the optical element are deteriorated, resulting in a problem that the life of the projection exposure apparatus is shortened.

  Accordingly, an object of the present invention is to provide an optical element that exhibits good reflection characteristics over a long period of time when used under extreme ultraviolet light.

  Another object of the present invention is to provide a projection exposure apparatus in which the above optical element is incorporated as a projection optical system for extreme ultraviolet rays.

  In order to solve the above problems, an optical element according to the first invention includes (a) a supporting substrate, (b) a multilayer film that is supported on the substrate and reflects extreme ultraviolet rays, and (c). A protective layer is provided on the outermost layer of the multilayer film, and includes a protective layer containing at least one of an oxidation-resistant metal and a catalytic metal and a third element having neither oxidation resistance nor catalytic activity. . In the above optical element, the multilayer film is formed by alternately laminating a first layer made of a material having a large refractive index difference with respect to a refractive index of vacuum in the extreme ultraviolet region and a second layer made of a small material on the substrate. .

  In the present invention, the optical element is a reflective element having a multilayer film, and has good reflection characteristics against extreme ultraviolet rays and the like. In the present invention, the protective layer containing at least one of an oxidation-resistant metal and a catalytic metal and a third element having neither oxidation resistance nor catalytic activity is the outermost layer of the multilayer film. Provided on top. Here, the “oxidation resistant metal” means a metal having a property of suppressing an oxidation reaction caused by moisture, oxygen, or the like. The “catalytic metal” means a metal having a positive catalytic action that increases a reaction rate at which carbon in an organic substance is converted to carbon dioxide or the like. For example, when the protective layer contains an oxidation-resistant metal, it is possible to suppress the oxidative action of the optical element being eroded from the surface by moisture or oxygen present around the optical element. On the other hand, when the protective layer contains a catalytic metal, the carbon contained in the organic substance present around the optical element can be efficiently converted into a gas such as carbon dioxide by the positive catalytic action. Generation of a carbon film on the element surface can be suppressed. Furthermore, in the optical element of the present invention, since the protective layer contains the third type element having neither oxidation resistance nor catalytic activity, protection can be achieved by selecting the type of the third type element or selecting the composition ratio. The layer structure can be stabilized. In particular, the quality of the film including the degree of adhesion to the underlying multilayer film, the denseness of the protective film, the flatness of the film formation, and the like can be improved by selecting the type of the third type element.

  In the optical element according to the second invention, the protective layer is formed as an alloy in the optical element according to the first invention. In this case, a structure in which the metals are melted together can be obtained, and the oxidation resistance and catalytic activity are improved while ensuring the permeability, compared with the case where the oxidation resistant metal and the catalytic metal are used alone. A well-balanced protective film can be obtained. The “alloy” means not only an alloy composed of two or more kinds of metal elements, but also an alloy in a broad sense containing non-metal or metalloid elements in addition to metal elements.

  Further, in the optical element according to the third invention, in the optical element according to the first and second inventions, the third element is Si, Mo, Al, Ga, Ge, Sn, Sr, Ba, Sc, Y, It is at least one selected from the group consisting of La, Ca, Pr, Nd, Sm, Eu, Gd, Tb, Ti, Zr, V, Tc, Cr, B, Be, C, Cu, and Rb. These elements are relatively suitable for alloying. Here, silicon (Si), molybdenum (Mo), etc. not only reduce absorption and improve the reflection performance of the optical element, but also when the underlying multilayer film is formed of silicon, molybdenum, etc. Make compatibility relatively good. In addition, strontium (Sr), barium (Ba), scandium (Sc), yttrium (Y), lanthanum (La), calcium (Ca), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu) ), Gadolinium (Gd), terbium (Tb), titanium (Ti), zirconium (Zr), vanadium (V), technetium (Tc), boron (B), beryllium (Be), carbon (C), copper (Cu) ) Etc. reduce the absorption and improve the reflection performance of the optical element. Further, chromium (Cr) or the like tends to be stabilized by changing to an oxide on the surface, so that the oxide functions as a barrier film against moisture, oxygen, and the like. Furthermore, since aluminum (Al), gallium (Ga), germanium (Ge), tin (Sn), etc. also tend to be stabilized by changing to oxides on the surface, such oxides are barriers against moisture and oxygen. Functions as a membrane.

  In the optical element according to the fourth invention, in the optical element according to the first to third inventions, the oxidation-resistant metal is made of Nb, Ru, Rh, Pt, Au, Ag, Pd, Os, and Ir. It is at least one selected from the group. In this case, niobium, ruthenium, rhodium, platinum, gold, silver, Pd, Os, and Ir contribute to the improvement of oxidation resistance and enhance the property of protecting the multilayer film from moisture, oxygen, and the like.

  In the optical element according to the fifth invention, in the optical elements according to the first to fourth inventions, the catalytic metal is at least one selected from the group consisting of Ni, Pd, Pt, Ag, Rh, and Ru. It is a seed. In this case, nickel, palladium, platinum, silver, rhodium, and ruthenium contribute to the improvement of catalytic activity and enhance the property of suppressing the formation of a carbon film on the surface of the optical element.

  According to a sixth aspect of the present invention, there is provided a projection exposure apparatus comprising: (a) a light source that generates extreme ultraviolet light; (b) an illumination optical system that guides extreme ultraviolet light from the light source to a transfer mask; and (c) a mask pattern. A projection optical system for forming an image on a sensitive substrate. In the projection exposure apparatus, at least one of the mask, the illumination optical system, and the projection optical system includes the optical element according to any of the first to fifth inventions.

  In the projection exposure apparatus, by using any one of the optical elements described above, the surface of the optical element and the oxidation in the vicinity thereof and the formation of a carbon film can be suppressed in the apparatus. Thus, the optical element and the projection exposure apparatus have a long life.

[First Embodiment]
FIG. 1 is a cross-sectional view showing the structure of the optical element according to the first embodiment. The optical element 40 of the present embodiment is, for example, a concave reflecting mirror, and includes a substrate 10 that supports a multilayer film structure, a reflective multilayer film 20, and a protective layer 30 that is a surface layer.

  The substrate 10 is formed by processing, for example, synthetic quartz glass or low expansion glass, and its upper surface 10a is polished to a mirror surface with a predetermined accuracy. The upper surface 10a can be a concave surface as shown in the figure, but can be a convex surface, a flat surface, a multi-surface, or other shapes depending on the application of the optical element 40.

The multilayer film 20 is a reflective film composed of several to several hundred thin films formed by, for example, alternately laminating two kinds of substances having different refractive indexes on the substrate 10. The multilayer film 20 is formed by laminating a large number of materials with low absorption in order to increase the reflectance of the optical element 40 that is a reflecting mirror, and based on the optical interference theory so that the phases of the reflected waves are matched. The thickness of each layer is adjusted. That is, the thin film layer L1 having a relatively low refractive index and the thin film layer L2 having a relatively high refractive index are reflected on the substrate 10 with respect to the wavelength region of extreme ultraviolet rays used in the projection exposure apparatus. The multilayer film 20 is formed by stacking alternately or in an arbitrary order with a predetermined film thickness so that the phases are matched. The two types of thin film layers L1 and L2 constituting the multilayer film 20 can be a molybdenum layer and a silicon layer, respectively. The order in which the thin film layers L1 and L2 are stacked and the condition of which thin film layer is the uppermost layer can be changed as appropriate according to the application of the optical element 40. The material of the thin film layers L1 and L2 is not limited to the combination of molybdenum and silicon. For example, the multilayer film 20 can be formed by appropriately combining a material such as molybdenum, ruthenium, or rhodium with a material such as silicon, beryllium, or carbon tetraboride (B ₄ C).

In the multilayer film 20, a boundary film (not shown) can be further provided between the thin film layer L1 and the thin film layer L2. In particular, when metal, silicon, or the like is used as the thin film layers L1 and L2 forming the multilayer film 20, the materials forming the respective materials are mixed in the vicinity of the boundary between the thin film layer L1 and the thin film layer L2, and the interface is ambiguous. It is easy to become. Thereby, the reflection characteristic is affected, and the reflectance of the optical element 40 may be lowered. Therefore, in order to clarify the interface, a boundary film is further provided between the thin film layer L1 and the thin film layer L2 when the multilayer film 20 is formed. As the material, for example, carbon tetraboride, carbon, molybdenum carbide (MoC), MoO ₂ or the like is used. By clarifying the interface in this way, the reflection characteristics of the optical element 40 are improved.

  The protective layer 30 covers the entire surface of the multilayer film 20 to protect the multilayer film 20 from the surrounding environment (generally, a reduced pressure or vacuum environment that efficiently transmits extreme ultraviolet rays).

  The protective layer 30 is formed according to the application and use conditions of the optical element 40: (1) an alloy of an oxidation-resistant metal and other metal, (2) an alloy of a catalytic metal and other metal, (3) It is formed of any of an alloy of an oxidation resistant metal, a catalytic metal, and another metal.

(1) In the case of an alloy of an oxidation resistant metal and another metal (a third type metal) In the first case, the protective layer 30 is an alloy of an oxidation resistant metal and a third type metal or an alloy material containing these. It is formed. More specifically, the protective layer 30 includes at least one selected from the group consisting of niobium, ruthenium, rhodium, platinum, gold, silver, osmium, and iridium as an oxidation resistant metal, and includes silicon, molybdenum, strontium. At least one selected from the group consisting of: barium, scandium, yttrium, lanthanum, calcium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, titanium, zirconium, vanadium, technetium, aluminum, gallium, germanium, and tin These are included as three kinds of metals and alloyed with them. Thereby, the protective layer 30 serves as an antioxidant film that is structurally stable and has relatively little transmission loss. That is, by forming the protective layer 30 of the alloy containing the oxidation-resistant metal or the third type metal on the outermost surface of the optical element 40, the optical layer 40 is optically affected by moisture or oxygen supplied to the surface of the optical element 40 or in the vicinity thereof. The element 40 (particularly the multilayer film 20) can be reliably prevented from being eroded, and the reflectance of the optical element 40 can be prevented from gradually decreasing due to such erosion.

(2) In the case of an alloy of a catalytic metal and another metal (a third type metal) In the second case, the protective layer 30 is an alloy of a catalytic metal and a third type metal or an alloy material containing these. It is formed. More specifically, the protective layer 30 includes at least one selected from the group consisting of nickel, palladium, platinum, silver, rhodium, and ruthenium as a catalytic metal, and includes silicon, molybdenum, strontium, barium, and scandium. At least one selected from the group consisting of yttrium, lanthanum, calcium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, titanium, zirconium, vanadium, technetium, aluminum, gallium, germanium, and tin Including and alloying them. Thereby, the protective layer 30 plays a role as a carbon suppression film that is structurally stable and has relatively little transmission loss. That is, by forming the protective layer 30 containing the catalytic metal or the third type metal on the outermost surface of the optical element 40, carbon in the organic substance supplied to the surface of the optical element 40 or in the vicinity thereof is carbon dioxide. Can be converted to Therefore, it is possible to reliably suppress the occurrence of a photo CVD phenomenon in which the carbon film is gradually deposited on the surface of the optical element 40, and it is possible to prevent the reflectance of the optical element 40 from gradually decreasing as the carbon film is deposited.
In addition, platinum, rhodium, ruthenium, and palladium show not only catalytic activity but also oxidation resistance. In the second case, focusing on these catalytic properties, the catalytic functions of these metals are promoted. To be added as an alloy component.

(3) In the case of an alloy of an oxidation resistant metal, a catalytic metal and another metal (a third type metal) In the third case, the protective layer 30 is composed of an oxidation resistant metal, a catalytic metal and a third type. It is made of a metal alloy or an alloy material containing these. More specifically, the protective layer 30 includes at least one selected from the group consisting of niobium, ruthenium, rhodium, platinum, gold, silver, and palladium as an oxidation resistant metal, and includes nickel, palladium, platinum, silver And at least one selected from the group consisting of rhodium and ruthenium as a catalytic metal. Here, platinum, rhodium, ruthenium, and palladium alone exhibit oxidation resistance and catalytic activity, but in the third case, they are added to the alloy components as one of the categories. In the third case, the protective layer 30 is made of silicon, molybdenum, strontium, barium, scandium, yttrium, lanthanum, calcium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, titanium, zirconium, vanadium, technetium, aluminum. At least one selected from the group consisting of gallium, germanium, and tin is included as the third-type metal. Thereby, the protective layer 30 plays a role as an antioxidant film and a carbon suppression film that are structurally stable and have relatively little absorption. That is, by forming the protective layer 30 containing the oxidation-resistant metal, the catalytic metal, and the third type metal on the outermost surface of the optical element 40, the optical element 40 is eroded by moisture and oxygen. Since it can be surely prevented and the occurrence of the photo-CVD phenomenon in which the carbon film is gradually deposited on the optical element 40 can be surely suppressed, the reflectance of the optical element 40 can be prevented from gradually decreasing.

  In the first and third cases described above, of the oxidation-resistant metals, niobium, ruthenium, rhodium, etc. have the feature of low absorption at the extreme ultraviolet wavelength, and can be the main component of the alloy. Further, in the second and third cases, among the catalytic metals, palladium, rhodium, ruthenium and the like have a feature of low absorption at the wavelength of extreme ultraviolet rays and can be the main component of the alloy. In the first to third cases, among the third type metals, silicon, molybdenum, strontium, barium, scandium, yttrium, lanthanum, calcium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, titanium, zirconium, Vanadium, technetium, and the like have a feature of low absorption at the extreme ultraviolet wavelength, and can be a main component of the alloy.

  Furthermore, silicon and molybdenum not only enhance the reflection performance of the optical element 40 but also relatively improve the compatibility between the protective layer 30 and the multilayer film 20 because the multilayer film 20 is formed of silicon or molybdenum. In addition, chromium (Cr) or the like tends to be stabilized by changing to an oxide on the surface, and in that sense, moisture and oxygen are prevented from entering the protective layer 30 and have oxidation resistance. Can do. In addition, aluminum, gallium, germanium, tin, and the like also tend to be stabilized by changing to oxides on the surface, so that moisture and oxygen are prevented from entering the protective layer 30 and have oxidation resistance. be able to.

Hereinafter, a specific manufacturing example will be described. For example, PdSi, PtSi, Nb ₃ Al, Nb ₃ Ga, Nb ₃ Ge, Nb ₃ Sn, or the like was used as a specific alloy constituting the protective layer 30.

In addition to the above-described PdSi, PtSi, Nb ₃ Al, Nb ₃ Ga, Nb ₃ Ge, Nb ₃ Sn, and the like, the alloy material constituting the protective layer 30 includes Ru ₂ Sc, RuSc, Ru ₄ Sc _{11 and the} like. A RuSc-based alloy can be used. Similarly, RuY alloys such as Ru ₂ Y, RuY ₃ , Ru ₂ Y ₅ , Ru ₂ Y ₃ , Ru ₃ Y ₅ can be used.

Further, as another alloy material constituting the protective layer 30, a LaRu-based alloy such as La ₃ Ru, La ₃ Ru ₂ , LaRu ₂ or the like can be used. Similarly, LaRh alloys such as La ₃ Rh, La ₅ Rh ₄ , La ₂ Rh ₇ , LaRh ₃ , La ₄ Rh ₃ , LaRh, LaRh _2, etc. can be used.

Further, as another alloy material constituting the protective layer 30, CaPd-based alloys such as Ca ₉ Pd, Ca ₃ Pd, Ca ₅ Pd ₂ , Ca ₃ Pd ₂ , and CaPd can be used.

Further, as another alloy material constituting the protective layer 30, an NdRu-based alloy such as Nd ₃ Ru, Nd ₅ Ru ₂ or NdRu ₂ can be used. _Similarly, it is possible to use _{Nd 4 Rh, Nd 3 Rh,} Nd 5 Rh 3, Nd 4 Rh 3, NdRh, NdRh 2, NdRh 3, Nd 4 NdRh alloy of Rh and the like.

Further, as another alloy material constituting the protective layer 30, a RuSm alloy such as Ru ₂ Sm, Ru ₂ Sm ₅ , RuSm ₃ can be used.

Further, as another alloy material constituting the protective layer 30, EuPd-based alloys such as Eu ₅ Pd ₂ , Eu ₃ Pd ₂ , EuPd, EuPd ₂ , EuPd ₃ , EuPd ₆ can be used.

Moreover, GdRu type alloys such as Gd ₃ Ru, Gd ₅ Ru ₂ , Gd ₅ Ru ₃ , and GdRu ₂ can be used as another alloy material constituting the protective layer 30. Similarly, GdRh alloys such as GdRh ₂ , GdRh ₃ , GdRh ₅ , Gd ₃ Rh, Gd ₇ Rh ₃ , Gd ₅ Rh ₃ , Gd ₃ Rh ₂ , Gd ₄ Rh ₃ , and GdRh can be used. Similarly, GdPd-based alloys such as Gd ₅ Pd ₂ , Gd ₃ Pd ₂ , GdPd, Gd ₂ Pd ₃ , Gd ₄ Pd ₅ , GdPd ₂ , GdPd ₃ can be used.

Further, as another alloy material constituting the protective layer 30, a TiRu-based alloy such as TiRu can be used. Similarly, TiRh alloys such as TiRh, Ti ₂ Rh, TiRh ₃ , Ti ₃ Rh ₅ , and TiRh ₅ can be used.

  Further, as another alloy material constituting the protective layer 30, a RuZr-based alloy such as Ru2Zr or RuZr can be used. Similarly, a RuV alloy such as RuV can be used.

As another alloy material constituting the protective layer 30, RhZr alloys such as Rh ₃ Zr, RhZr, Rh ₅ Zr ₃ , RhZr ₂ can be used.

Further, as another alloy material constituting the protective layer 30, a MoRh-based alloy such as MoRh, MoRh ₃ can be used. Similarly, a MoPd-based alloy such as MoPd ₂ can be used.

Other alloy materials constituting the protective layer 30 include NbSi-based alloys such as Nb ₅ Si ₃ and NbSi ₂ , RuSi-based alloys such as Ru ₂ Si, RuSi and Ru ₂ Si ₃ , Pd ₃ Si and Pd _2. PdSi alloys such as Si, Pd ₉ Si ₄ , BeNb alloys such as Be ₁₂ Nb, Be ₁₇ Nb ₂ , Be ₃ Nb, Be ₂ Nb, Be ₂ Nb ₃ , Be ₁₇ Ru ₃ , Be ₁₀ Ru ₃ , Be BeRu alloys such as ₂ Ru and Be ₃ Ru ₂ , BePd alloys such as Be ₁₂ Pd, Be ₅ Pd, BePd ₂ , BePd ₃ , BePd, Be ₂ Pd ₃ and Be ₃ Pd ₄ , Nb ₃ B ₂ and NbB , _Nb 3 _B 4, NbB _2, etc. NbB based _{alloy, RuB, Ru 7 B 3,} Ru 2 B 3, RuB 2 etc. RuB based _alloy, RhB _{1.1, Rh} 7 _{B 3} RhB based alloys, as well _as, Nb 2 C, can be used NbC-based alloy such as NbC.

  The various types of protective layer 30 described above can be produced by various film forming methods such as vapor deposition and sputtering as long as a dense film can be formed without deteriorating the surface roughness. Further, in forming the protective layer 30, a large film thickness is desired in order to make maximum use of oxidation resistance and catalytic activity. However, extreme ultraviolet rays are often absorbed by the protective layer 30, and the thickness of the protective layer 30 is, for example, 4 nm or less. The specific thickness is appropriately determined according to the reflection characteristics desired for the optical element 40.

[Second Embodiment]
FIG. 2 is a cross-sectional view showing the structure of the optical element according to the second embodiment. The optical element 140 of the present embodiment is a modification of the optical element 40 of the first embodiment shown in FIG. 1, and the same portions are denoted by the same reference numerals and redundant description is omitted. Further, parts that are not particularly described are the same as those in the first embodiment.

  In the present optical element 140, the composite protective layer 130 includes an auxiliary layer 131 provided on the outermost layer of the multilayer film 20, and a main body protective layer 132 provided on the auxiliary layer 131 and serving as the outermost surface of the optical element 40. Prepare.

  Of these, the main body protective layer 132 corresponds to the protective layer 30 of FIG. 1 and is formed of an alloy material of an oxidation-resistant metal and / or a catalytic metal and another metal (a third type metal). Has been.

On the other hand, the auxiliary layer 131 is one of inorganic oxides such as silicon dioxide (SiO ₂ ), niobium oxide (NbO, NbO ₂ , Nb ₂ O ₅ ), chromium oxide (CrO, Cr ₂ O ₃ , CrO ₃ ). Or a material containing a combination thereof as a main component. When the auxiliary layer 131 containing these is formed as a part of the protective layer 30, the material constituting the main body protective layer 132 diffuses into the multilayer film 20, that is, oxidation resistant gold, catalytic metal, type 3 It is possible to prevent diffusion of metal or the like and more reliably prevent a decrease in reflectance while suppressing deterioration of reflection characteristics of the optical element 140 under irradiation of extreme ultraviolet rays.

  In addition to the above-described silicon dioxide or the like, single boron can be used as the diffusion preventing material constituting the auxiliary layer 131.

  In addition, oxides, borides, silicides, carbides, nitrides, fluorides, and beryllium compounds of nonmetallic elements such as silicon and boron, Be, Ca, Sc, Gd, Ti, Zr, Ta, Cr, and Mo , W, Zr, Ga, Sr, Nb, Ba, La, Dy, Hf, Mn, Re, Fe, Pd, Th, V, Ru, Rh, Tb, Y, Nd, Al, Ni, Eu, Pr, Sm , Rb and other metal oxides, borides, silicides, carbides, nitrides, fluorides, and beryllium compounds can be used.

Specifically, non-metal oxides such as SiO and B ₂ O ₃ can be used as the diffusion preventing material constituting the auxiliary layer 131. Al ₂ O ₃ , ZrO ₂ , Sc ₂ O ₃ , Tb ₂ O ₃ , PdO, Pd ₂ O ₃ , PdO ₄ , RuO ₂ , RuO ₃ , RuO ₄ , Rh ₂ O ₃ , RhO ₂ , TiO, Ti Metal oxides such as ₂ O ₃ , TiO ₂ , MoO, Mo ₂ O ₃ , MoO ₂ , Mo ₂ O ₅ , VO, V ₂ O ₃ , VO ₂ , V ₂ O ₅ can be used. _{Further, BaO, BeO, Be 2 O} , CaO, Eu 2 O 3, Gd 2 O 3, La 2 O 3, Mo 4 O 11, Mo 8 O 23, MoO 3, Mo 9 O 24, NdO, Nd 2 O _{3, PrO 1.778, PrO 1.833,} PrO 1.8, PrO 1.818, Sm 2 O 3, SrO, Ti 3 O 2, Ti 2 O, Ti 3 O, Ti 1-x O, Ti n O _2n-1 (n = 2-9), VO _1.76 , VO _1.57 , VO _1.80 , VO _1.84 , VO _1.86 , V ₆ O ₁₃ , V ₈ O, V ₄ O, Metal oxides such as V ₂ O, V ₃ O ₅ , V ₄ O ₇ , V ₅ O ₉ , V ₇ O ₁₃ , V ₆ O ₁₃ , Y ₂ O ₃ , ZrO _2-x can also be used.

As the diffusion preventing material constituting the auxiliary layer 131, non-metal borides such as SiB ₃ , SiB ₆ and SiB _x can be used. _{Further, BeB 2, CaB 6, ScB} 2, ScB 12, GdB 6, TiB 2, ZrB 2, TaB 2, Cr 4 B, CrB, Cr 3 B 4, CrB 2, Mo 2 B 5, W 2 B 3, Metal borides such as W ₂ B ₅ , ZrB ₁₂ , GaB ₆ , SrB ₆ , NbB, Nb ₃ B ₄ , and NbB ₂ can be used. _{Further, BeB 12, BeB 9, BeB} 6, BeB 4, Be 2 B, Be 4 B, EuB 6, GdB 2, Gd 2 B 5, GdB 4, GdB 66, Mo 2 B, MoB, Mo 3 B 2, _{MoB 2, MoB 4, Nb 3} B 2, Nd 2 B 5, NdB 4, NdB 6, NdB 66, Pr 2 B 5, PrB 4, PrB 6, RhB 1.1, Rh 7 B 3, RuB, Ru 7 _{B 3, Ru 2 B 3,} RuB 2, Sm 2 B 5, SmB 4, SmB 6, SmB 66, TbB 2, TbB 4, TbB 6, TbB 12, TbB 66, TiB, Ti 3 B 4, V 3 B _{2, VB, V 5 B 6} , V 3 B 4, V 2 B 3, a metal boride VB _2, etc. can be used.

As the diffusion preventing material constituting the auxiliary layer _{131, BaSi 2, LaSi 2,} DySi 2, ZrSi, ZrSi 2, HfSi 2, CrSi 2, MoSi 2, MnSi 2, ReSi 2, FeSi 2, PdSi, ThSi 2, CaSi, Metal silicides such as Ca ₂ Si, CaSi ₂ , V ₂ Si, VSi ₂ , RuSi, RhSi ₂ , and TbSi ₂ can be used. In addition, BaSi, Mo ₃ Si, Mo ₅ Si ₃ , Nb ₅ Si ₃ , NbSi ₂ , Pd ₃ Si, Pd ₂ Si, Pd ₉ Si ₄ , Ru ₂ Si, Ru ₂ Si ₃ , Sr ₂ Si, SrSi ₂ , _{SrSi, TiSi, Ti 3 Si,} Ti 5 Si 3, Ti 3 Si, Ti 5 Si 4, TiSi 2, Ti 6 Si 5, V 3 Si, V 5 Si 3, V 6 Si 5, Y 5 Si 3, Y _{5 Si 4, YSi, Y 3} Si 5, Zr 2 Si, Zr 4 Si, Zr 5 Si 3, Zr 3 Si 2, Zr metal silicide such as 5 Si ₄ can also be used.

As the diffusion preventing material constituting the auxiliary layer 131, non-metal carbides such as SiC and B ₄ C can be used. Also, metal carbides such as LaC ₂ , Be ₂ C, Mo ₂ C, MoC, VC, V ₄ C ₃ , V ₅ C, TiC, and ZrC can be used. Furthermore, Eu ₄ C ₂ , Eu ₂ C ₃ , EuC ₂ , EuC ₆ , Gd ₂ C, Gd ₄ C ₂ , Gd ₂ C ₃ , GdC ₂ , La ₂ C ₃ , MoC _1-x , Nb ₂ C, NbC , Nd ₂ C ₃ , NdC ₂ , Sc ₂ C, Sc ₄ C ₃ , Sc ₁₃ C ₁₀ , Sc ₁₅ C ₁₉ , Sm ₃ C, Sm ₂ C ₃ , SmC ₂ , Tb ₄ C ₂ , Tb ₂ C, Tb _{2 C 3, TbC 2, Ti} 2 C, V 2 C, V 4 C 3-x, V 6 C 5, V 8 C 7, Y 2 C, Y 4 C 2, Y 15 C 19, Y 2 C 3 , YC _{2 and} other metal carbides can also be used.

Non-metal nitrides such as SiN, Si ₂ N ₃ , Si ₃ N ₄ , BN, and BN ₂ can be used as the diffusion preventing material constituting the auxiliary layer 131. _{Moreover, YN, Ca 3 N 2,} ScN, ZrN, Zr 3 N 2, Sr 3 N 2, TiN, Ti 3 N 4, NbN, NdN, Be 3 N 2, Ba 3 N 2, VN, MoN, Mo 2 Metal nitrides such as N, LaN, and AlN can be used. Further, non-metal nitrides such as Nb ₂ N, Ti ₂ N, V ₂ N _1-x , VN _1-x , V ₃₂ N ₂₈ can be used.

A metal fluoride such as SrF ₂ , NiF ₂ , YF ₃ can be used as the diffusion preventing material constituting the auxiliary layer 131.

As the diffusion preventing material constituting the auxiliary layer _{131, BaBe 13, CaBe 13,} EuBe 13, GdBe 13, LaBe 13, Mo 3 Be, MoBe 2, MoBe 12, NbBe 12, Nb 2 Be 17, NbBe 3, NbBe 2, _{nb 3 Be 2, NdBe 13,} PdBe 12, PdBe 5, Pd 2 Be, Pd 3 Be, PdBe, Pd 3 Be 2, Pd 4 Be 3, PrBe 13, Ru 3 Be 17, Ru 3 Be 10, RuBe 2, _{ru 2 Be 3, ScBe 5,} Sc 2 Be 17, ScBe 13, SmBe 13, SrBe 13, TbBe 13, TiBe 2, TiBe 3, Ti 2 Be 17, TiBe 12, VBe 12, VBe 2, YBe 13, ZrBe 13 , Zr ₂ Be ₁₇ , ZrB Metal beryllium compounds such as e ₅ and ZrBe ₂ can be used.

  Note that the auxiliary layer 131 may be manufactured by any method such as vapor deposition or sputtering as long as a dense film can be formed without deteriorating the surface roughness. In order to help form a dense film without deteriorating the surface roughness, another material may be formed between the film, that is, the auxiliary layer 131 and the multilayer film 20. In addition, the thickness of the whole protective layer 30 is made into the range which does not reduce the transmittance | permeability, for example, shall be 4 nm or less. The specific thickness is appropriately determined according to the reflection characteristics desired for the optical element 140.

[Third Embodiment]
FIG. 3 is a view for explaining the structure of a projection exposure apparatus according to the third embodiment in which the optical elements 40 and 140 of the first and second embodiments are incorporated as optical components.

  As shown in FIG. 3, the projection exposure apparatus 200 includes, as an optical system, a light source device 50 that generates extreme ultraviolet rays (wavelength 11 to 14 nm), and an illumination optical system 60 that illuminates the mask MA with extreme ultraviolet illumination light. And a projection optical system 70 for transferring the pattern image of the mask MA to the wafer WA, which is a sensitive substrate, and as a mechanical mechanism, a mask stage 81 for supporting the mask MA and a wafer stage 82 for supporting the wafer WA are provided.

  The light source device 50 includes a laser light source 51 that generates laser light for plasma excitation, and a tube 52 that supplies a gas such as xenon that is a target material into the housing SC. Further, the light source device 50 is provided with a capacitor 54 and a collimator mirror 55. By condensing the laser light from the laser light source 51 with respect to xenon emitted from the tip of the tube 52, the target material in that portion is turned into plasma to generate extreme ultraviolet rays. The condenser 54 collects extreme ultraviolet light generated at the tip S of the tube 52. The extreme ultraviolet rays that have passed through the condenser 54 are emitted outside the casing SC while being converged, and enter the collimator mirror 55. In place of the light source light from the laser plasma type light source device 50 as described above, radiation light from a discharge plasma light source, a SOR light source, or the like can be used.

  The illumination optical system 60 includes reflection type optical integrators 61 and 62, a condenser mirror 63, a deflection mirror 64, and the like. Light source light from the light source device 50 is condensed by the condenser mirror 63 while being made uniform as illumination light by the optical integrators 61 and 62, and is incident on a predetermined region (for example, a belt-like region) on the mask MA through the deflection mirror 64. As a result, a predetermined area on the mask MA can be uniformly illuminated by extreme ultraviolet rays having an appropriate wavelength.

  Note that there is no substance having sufficient transmittance in the wavelength range of extreme ultraviolet rays, and a reflective mask is used as the mask MA instead of a transmissive mask.

  The projection optical system 70 is a reduction projection system including a large number of mirrors 71, 72, 73 and 74. A circuit pattern, which is a pattern image formed on the mask MA, forms an image on the wafer WA coated with a resist by the projection optical system 70 and is transferred to the resist. In this case, the area where the circuit pattern is projected at once is a linear or arc-shaped slit area, and a rectangular pattern formed on the mask MA, for example, by scanning exposure that moves the mask MA and the wafer WA synchronously. This circuit pattern can be transferred to a rectangular area on the wafer WA without waste.

Of the light source device 50 described above, the portion disposed on the optical path of extreme ultraviolet rays, the illumination optical system 60, and the projection optical system 70 are disposed in the vacuum vessel 84, and attenuation of exposure light is prevented. Yes. That is, the extreme ultraviolet rays are absorbed and attenuated by the atmosphere, but the entire apparatus is blocked from the outside by the vacuum vessel 84 and the optical path of the extreme ultraviolet rays is set to a predetermined degree of vacuum (for example, 1.3 × 10 ⁻³ Pa or less). By maintaining it, the attenuation of extreme ultraviolet rays, that is, the decrease in brightness and contrast of the transferred image is prevented.

  In the above projection exposure apparatus, the optical elements 54, 55, 61, 62, 63, 64, 71, 72, 73, 74 and the mask MA, which are arranged on the optical path of extreme ultraviolet rays, and the mask MA are exemplified in FIG. Elements 40 and 140 are used. At this time, the shape of the optical surface of the optical elements 40 and 140 is not limited to the concave surface, and is appropriately adjusted depending on the place of incorporation such as a flat surface, a convex surface, or a multi-surface.

  The operation of the projection exposure apparatus shown in FIG. 3 will be described below. In this projection exposure apparatus, the mask MA is illuminated by illumination light from the illumination optical system 60, and a pattern image of the mask MA is projected onto the wafer WA by the projection optical system 70. As a result, the pattern image of the mask MA is transferred to the wafer WA.

  In the projection exposure apparatus described above, the optical elements 54, 55, 61, 62, 63, 64, 71, 72, 73, 74, MA, which are controlled with high reflectivity and high accuracy, are used. Exposure is possible. Further, in this projection exposure apparatus, the oxidation reaction is suppressed on the surface of the optical elements 54, 55, 61, 62, 63, 64, 71, 72, 73, 74, MA, that is, the optical surface, or the formation of the carbon film is suppressed. Therefore, it is possible to prevent the reflection characteristics of these optical elements from deteriorating and thereby to prolong the life of the projection exposure apparatus.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments. For example, in the above-described embodiment, the projection exposure apparatus using extreme ultraviolet rays as the exposure light has been described. However, in the projection exposure apparatus using ultraviolet rays other than extreme ultraviolet rays as the exposure light, the optical elements 40 and 140 as shown in FIG. And the deterioration of the reflection characteristics of the optical element can be suppressed.

  In addition to the projection exposure apparatus, for example, various optical instruments including soft X-ray optical instruments such as a soft X-ray microscope and a soft X-ray analyzer are similarly used in the optical elements 40 and 140 shown in FIG. Can be incorporated.

It is sectional drawing explaining the optical element which concerns on 1st Embodiment. It is sectional drawing explaining the optical element which concerns on 2nd Embodiment. It is a figure explaining the projection exposure apparatus which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 20 ... Multilayer film, L1, L2 ... Thin film layer, 30 ... Protective layer, 130 ... Composite protective layer, 40, 140 ... Optical element, 50 ... Light source device, 51 ... Laser light source, 54, 55, 61, 62, 63, 64, 71, 72, 73, 74 ... optical elements, 60 ... illumination optical system, 70 ... projection optical system, 81 ... mask stage, 82 ... wafer stage, 84 ... vacuum vessel, 200 ... projection exposure apparatus

Claims (6)

A supporting substrate;
A multilayer film supported on the substrate and reflecting extreme ultraviolet rays;
A protective layer provided on the outermost layer of the multilayer film and containing at least one of an oxidation-resistant metal and a catalytic metal, and a third element that has neither oxidation resistance nor catalytic activity;
An optical element comprising:   The optical element according to claim 1, wherein the protective layer is formed as an alloy.   The third element is Si, Mo, Al, Ga, Ge, Sn, Sr, Ba, Sc, Y, La, Ca, Pr, Nd, Sm, Eu, Gd, Tb, Ti, Zr, V, Tc. The optical element according to claim 1, wherein the optical element is at least one selected from the group consisting of Cr, B, Be, C, Cu, and Rb.   The oxidation-resistant metal is at least one selected from the group consisting of Nb, Ru, Rh, Pt, Au, Ag, Pd, Os, and Ir. An optical element according to claim 1.   5. The optical device according to claim 1, wherein the catalytic metal is at least one selected from the group consisting of Ni, Pd, Pt, Ag, Rh, and Ru. element. A light source that generates extreme ultraviolet radiation;
An illumination optical system that guides extreme ultraviolet rays from the light source to a transfer mask;
A projection optical system that forms a pattern image of the mask on a sensitive substrate;
6. A projection exposure apparatus, wherein at least one of the mask, the illumination optical system, and the projection optical system includes the optical element according to any one of claims 1 to 5.

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