Membranes, components and equipment

Abstract

This invention relates to membranes, elements, and devices. One membrane comprises an amorphous transition metal oxide as the main component and more than 1.0 at% hydrogen.

Description

Technical Field

[0001] This invention relates to films comprising metal oxides. Background Technology

[0002] The applications of metal oxides in optical components, electronic components, and semiconductor components were considered.

[0003] In various optical devices such as exposure apparatus, optical elements are coated with optical films to improve optical properties such as anti-reflection and reflection characteristics. In capacitor elements or semiconductor elements, insulating films are used to insulate capacitor electrodes, gate electrodes, and other components from other parts.

[0004] As performance standards for optical equipment improve, the number of optical components used in these devices is trending upwards, as is the number of optical surfaces requiring optical film coating. Furthermore, the optical films used for coating are not necessarily single-layered and can, in some cases, consist of multiple layers, thus increasing the total number of layers.

[0005] In the field of optical components, attempts are being made to use films containing metal oxides as optical films to coat optical components, such as lenses or filters.

[0006] Japanese Patent Publication No. H10-217377 discloses a dielectric multilayer film for optical components containing hydrogen to suppress the degradation of the dielectric multilayer film. The hydrogen content in the dielectric film causes lattice defects that lead to light absorption, thus attempting to extend the lifetime of the dielectric multilayer film. Examples of hydrogen-containing dielectric multilayer films disclosed include SiO2, Al2O3, TiO2, Ta2O5, HfO2, and ZrO2.

[0007] Japanese Patent Publication No. H10-217377 discloses a technique for providing highly durable dielectric multilayer films for optical components using hydrogen-containing SiO2 or TiO2 dielectric films. Although hydrogen-containing Ta2O5, HfO2, Al2O3, and ZrO2 are suggested as examples of dielectric materials other than SiO2 and TiO2, their details are not disclosed.

[0008] Japanese Patent Publication No. 2012-506950 discloses a technique for reducing the internal stress of a coating by adding 1 at% to 10 at% silicon to suppress light absorption and light scattering when using hafnium oxide as an optical film.

[0009] In the field of semiconductor devices, attempts have been made to use films containing hafnium oxide as gate insulating films for transistors. However, a problem arises when using high-dielectric-constant films containing hafnium oxide as gate insulating films for transistors: high-temperature processing during manufacturing leads to crystallization, resulting in increased leakage current through grain boundaries or defects.

[0010] Japanese Patent Publication No. 2006-165589 discloses a technique for forming a silicon-containing high-dielectric-constant film by dispersing silicon in hafnium oxide, in order to suppress the crystallization of high-dielectric-constant materials and the increase in leakage current during high-temperature processing after the formation of the gate insulating film.

[0011] Japanese Patent Publication No. 2017-83789 discloses a reflective optical element comprising an optical film with a designed center wavelength of 400 nm. Examples of materials disclosed as high-dielectric-constant layers for coating the optical film of the reflective optical element include tantalum oxide (Ta₂O₅), niobium oxide (NbO₅), titanium oxide (TiO₂), zirconium oxide (ZrO₂), zinc oxide (ZnO), hafnium oxide (HfO₂), aluminum oxide (AlN), and silicon nitride (SiN).

[0012] Japanese Patent Publication No. H07-311393 discloses a nonlinear driving element comprising tantalum metal as a bottom metal, tantalum oxide as an insulating film, and a transparent conductive film as a top metal, wherein the tantalum oxide as the insulating film has a hydrogen atom concentration of less than 1 at%.

[0013] In the field of optical components, there is a need for high-performance optical films. In the field of electronic components, there is a need for high-performance insulating films. Therefore, the object of this invention is to provide a technique that facilitates the control of the properties of films containing metal oxides. Summary of the Invention

[0014] According to a first aspect of the invention, the film comprises an amorphous transition metal oxide as the main component, and more than 1.0 at% hydrogen. The film is an optical film.

[0015] According to a second aspect of the invention, the membrane comprises an amorphous transition metal oxide as the main component, and 1.0 at% or more of hydrogen. The sum of the transition metal content, oxygen content, hydrogen content, and argon content of the membrane is 99.0 at% or more.

[0016] Other features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 It is a schematic cross-sectional view of the optical element according to the first embodiment.

[0018] Figure 2 This is a schematic diagram of a sputtering film forming apparatus for manufacturing optical elements according to the first embodiment.

[0019] Figure 3 This is a coordinate graph showing the light absorption characteristics relative to the hydrogen content of the hafnium oxide film.

[0020] Figure 4 This is a coordinate graph showing the refractive index characteristics relative to the hydrogen content of the hafnium oxide film.

[0021] Figure 5 This is a coordinate graph showing the wavelength dependence of light absorption in embodiments 1 and 3 of the first implementation scheme.

[0022] Figure 6 This is a coordinate graph showing the wavelength dependence of the refractive index of Examples 1 and 4 of the first embodiment.

[0023] Figure 7 This is a diagram showing the X-ray diffraction pattern of the hafnium oxide film of Example 1 of the first embodiment.

[0024] Figure 8 This is a diagram showing the X-ray diffraction pattern of the hafnium oxide film of Comparative Example 1 of the first embodiment.

[0025] Figure 9 These are cross-sectional views of the layered structures of embodiments 5 and 6 of the first implementation scheme.

[0026] Figure 10 This is a coordinate graph showing the refractive index characteristics of the optical structure (anti-reflection structure) of embodiments 5 and 6 of the first implementation scheme.

[0027] Figure 11 These are cross-sectional views of the layered structures of embodiments 7 and 8 of the first implementation scheme.

[0028] Figure 12 This is a coordinate graph showing the refractive index characteristics of the optical structure (anti-reflection structure) of embodiments 7 and 8 of the first implementation scheme.

[0029] Figure 13 This is a schematic cross-sectional view of a semiconductor device including a CMOS transistor according to Embodiment 11 of the second embodiment.

[0030] Figure 14 This is a schematic cross-sectional view of a semiconductor element including a thin-film transistor according to Embodiment 12 of the second embodiment.

[0031] Figure 15 This is a schematic partial cross-sectional view of a back-illuminated camera element according to Embodiment 13 of the second implementation scheme.

[0032] Figure 16 This is a schematic cross-sectional view of the optical element according to the third embodiment.

[0033] Figure 17 This is a schematic diagram of a sputtering film forming apparatus for manufacturing optical elements according to the third embodiment.

[0034] Figure 18 This is a coordinate graph showing the light absorption characteristics relative to the hydrogen content of the tantalum oxide film.

[0035] Figure 19 This is a coordinate graph showing the wavelength dependence of light absorption in Examples 4 and 5 of the third embodiment and Comparative Example 1.

[0036] Figure 20 These are cross-sectional views of the layered structures of Embodiments 6 and 7 of the third implementation scheme and Comparative Example 3.

[0037] Figure 21 This is a coordinate graph showing the wavelength dependence of reflectance of Embodiments 6 and 7 of the third embodiment and Comparative Example 3.

[0038] Figure 22 yes Figure 21 A magnified view of the short-wavelength side of the coordinate graph.

[0039] Figure 23 This is a coordinate graph showing the wavelength dependence of transmittance for Embodiments 6 and 7 of the third embodiment and Comparative Example 3.

[0040] Figure 24 This is a graph showing the relationship between hydrogen content and the refractive index of light at a wavelength of 365 nm.

[0041] Figure 25 These are cross-sectional views of the layered structures of Embodiment 8 and Comparative Example 4 of the third implementation scheme.

[0042] Figure 26 This is a coordinate graph showing the wavelength dependence of reflectance for Embodiment 8 and Comparative Example 4 of the third embodiment.

[0043] Figure 27 This is a diagram showing the X-ray diffraction pattern of the tantalum oxide film according to the third embodiment.

[0044] Figure 28 This is a schematic diagram illustrating the structure of the exposure apparatus of Embodiment 10 of the third embodiment.

[0045] Figure 29 This is a schematic cross-sectional view of the solid-state camera element in Embodiment 11 of the fourth implementation scheme. Detailed Implementation

[0046] Embodiments of the present invention will now be described with reference to the accompanying drawings. Several embodiments will be described sequentially, and specific examples of each embodiment will be described.

[0047] The membrane of the embodiment comprises an amorphous transition metal oxide as the main component and contains more than 1.0 at% hydrogen. In an element including this membrane, the membrane is disposed on a substrate included in the element. Amorphous means that when X-rays or an electron beam are irradiated onto the membrane as the object of measurement at a small incident angle of about 0.5° and a diffraction pattern is observed, no obvious diffraction peaks are detected; in other words, a halo pattern is observed. Therefore, the amorphous state described herein does not necessarily exclude the state including microcrystalline materials. As used herein, "at%" refers to "atomic percentage," that is, the ratio of the number of a particular atom in the composition of the object to the total number of atoms in the composition of the object.

[0048] In the following text, the specific target element among the transition elements will be referred to as transition metal T. Transition metal oxides are compounds of transition metal T and oxygen. Transition metal T is an element in Groups 3-11 of the periodic table and is a transition element. In transition elements where the d or f orbitals are not closed shells (unlike main group elements), the hydrogen or oxygen level affects the properties of the membrane.

[0049] Examples of metal oxides belonging to the fourth period (first transition elements; 3d transition elements) include titanium oxide (Ti2O3 / TiO2 / TiO; Group 4), vanadium oxide (VO2; Group 5), chromium oxide (Cr2O3; Group 6), cobalt oxide (Co3O4; Group 9), and nickel oxide (NiO; Group 10).

[0050] Examples of metal oxides belonging to transition elements in period 5 (second transition elements; 4d transition elements) include yttrium oxide (Y₂O₃; group 3), zirconium oxide (ZrO₂; group 4), niobium oxide (Nb₂O₅; group 5), and molybdenum oxide (MoO₃; group 6).

[0051] Examples of metal oxides belonging to transition elements in period 6 (third transition elements; 5d, 4f transition elements) include lanthanum oxide (La₂O₃; lanthanide), cerium oxide (CeO₂; lanthanide), samarium oxide (Sm₂O₃; lanthanide), ytterbium oxide (Yb₂O₃; lanthanide), hafnium oxide (HfO₂; group 4), tantalum oxide (Ta₂O₅; group 5), and tungsten oxide (WO₃; group 6).

[0052] Typically, oxides of transition metals from groups 3 to 6 can be used. In particular, oxides of transition metals from groups 4 or 5 are preferred. Furthermore, typically, oxides of transition metals from periods 4 to 6 can be used. In particular, oxides of transition metals from periods 5 or 6 are preferred.

[0053] In transition metal oxides, the content J (at%) of transition metal T, the oxygen content K (at%), and the hydrogen content L (at%) are defined, and J, K, and L > 0 hold. In transition metal oxides, the content M (at%) of impurity A and the content N (at%) of impurity B are defined. M and N ≥ 0 hold. Here, the case where there are two elements among the elements other than transition metal, oxygen, and hydrogen contained in the transition metal oxide will be taken as an example for explanation. That is, this transition metal oxide contains five elements. However, the elements other than transition metal, oxygen, and hydrogen contained in the transition metal oxide can be one element or three or more elements. That is, the number of elements contained in the transition metal element oxide can be 4, 6, or more.

[0054] A film including an oxide of transition metal T as a main component is a film in which the sum of the content J of transition metal T and the oxygen content K is greater than each of the contents L, M, and N of the elements other than transition metal T and oxygen in the film (J + K > L, J + K > M, and J + K > N). Since the transition metal oxide film of the present embodiment contains hydrogen in addition to transition metal and oxygen, the sum of the content J of transition metal T and the oxygen content K is less than 100 at% (J + K < 100 at%), and since the hydrogen content is 1.0 at% or more, the sum of the content J of transition metal T and the oxygen content K is 99.0 at% or less (J + K ≤ 99.0 at%).

[0055] Define the stoichiometric composition of an oxide of a certain transition metal T as T j O k . When k ≥ 1 holds, J×(k - 0.5) / j < K < J×(k + 0.5) / j can be satisfied, and when k ≥ 2 holds, J×(k - 1) / j < K < J×(k + 1) / j can be satisfied. The sum of the content J of transition metal T and the oxygen content K in the transition metal oxide film is preferably greater than the sum of the contents L, M, and N of all other elements other than transition metal T and oxygen contained in the transition metal oxide film. That is, it is preferably satisfied that J + K > L + M + N. In this case, J + K is greater than 50 at%.

[0056] Typically, hydrogen in the transition metal oxide film can exist in the form of being bonded to the transition metal T of the transition metal oxide to fill the oxygen defects of the transition metal oxide, or in the form of being bonded to the oxygen in the transition metal oxide. Therefore, in the transition metal oxide film, the hydrogen content L can be lower than the oxygen content K (L < K). In addition, the hydrogen content L of the transition metal oxide film can be lower than the content J of the transition metal T in the transition metal oxide film (L < J). A higher content J of the transition metal T in the transition metal oxide film than the hydrogen content L (J > L) is beneficial for obtaining a finer transition metal oxide film. The physical properties of a finer transition metal oxide film are usually very different from those of a vacuum. For example, the refractive index of a finer transition metal oxide film is very different from the physical properties of a vacuum with a refractive index of 1.0 and is thus higher. In order to obtain a finer transition metal oxide film, the hydrogen content L is preferably equal to or less than half of the content J of the transition metal T (L ≤ J / 2).

[0057] In the stoichiometric composition T j O k of the oxides of many transition elements, j ≤ k, especially j < k holds. Therefore, the oxygen content K is higher than the content J of the transition metal T (K > J).

[0058] As described above, the hydrogen content L is lower than the content J of the transition metal T and the oxygen content K (J, K > L). That is, typically K > J > L is satisfied.

[0059] The composition of the amorphous transition metal oxide film can typically deviate from the stoichiometric composition because the film is amorphous. That is, the ratio K / J between the content J of the transition metal T and the oxygen content K can be different from k / j of the stoichiometric composition T j O k of the transition metal oxide. For example, when the hydrogen in the film exists in the form of being bonded to the transition metal of the transition metal oxide to fill the oxygen defects in the transition metal oxide, K / J > k / j can hold. In addition, for example, when the hydrogen in the film exists in the form of being bonded to the oxygen in the transition metal oxide, K / J < k / j can hold.

[0060] Elements other than transition metals, oxygen, and hydrogen that can be included in the transition metal oxide film can be transition elements or main group elements. However, it is preferable to include as few elements other than transition metals, oxygen, and hydrogen as possible. Hereinafter, impurities A and B that can be included in the transition metal oxide film will be described.

[0061] The content M (at%) of impurity A is preferably lower than the hydrogen content L (M < L), but may also be higher than the hydrogen content L (M > L). The content M of impurity A may be 0.5 at% or more and 5.0 at% or less. When impurity A is an element of Group 18 of the periodic table (i.e., a noble gas), since impurity A is chemically inert, the characteristics of the transition metal oxide film can be easily controlled. Impurity A is typically argon, but may be krypton or xenon instead of argon.

[0062] The content N (at%) of the above-mentioned impurity B is lower than the content M of impurity A (N < M). In addition, the content N of impurity B is lower than the hydrogen content L (N < L). The content N of impurity B is preferably less than 1.0 at%, more preferably 0.5 at% or less. The content N of impurity B may be 0.05 at% or more and 0.5 at% or less. The content N of impurity B may be 0.

[0063] Impurity B may be a metal element, a transition element, and a transition element同族 with the transition metal T. When impurity B is同族 with the transition metal T in the periodic table, impurity B has chemical similarity with the transition metal T, and thus the characteristics of the transition metal oxide film can be easily controlled. For example, when the transition metal T is hafnium, impurity B may be zirconium, and when the transition metal T is zirconium, impurity B may be hafnium. For example, when the transition metal T is tantalum, impurity B may be niobium, and when the transition metal T is niobium, impurity B may be tantalum. For example, when the transition metal T is tungsten, impurity B may be molybdenum, and when the transition metal T is molybdenum, impurity B may be tungsten. For example, when the transition metal T is yttrium, impurity B may be a lanthanide element, and when the transition metal T is a lanthanide element, impurity B may be a different lanthanide element or yttrium.

[0064] The content of each main group element other than oxygen, hydrogen, and noble gas in the transition metal oxide film is preferably less than 1.0 at%, more preferably 0.5 at% or less, and further preferably 0.1 at% or less. The content of each main group element other than oxygen, hydrogen, and noble gas in the transition metal oxide film may be lower than the detection limit. Here, the main group elements are the elements of Groups 1, 2, and 12 to 18 of the periodic table, and the main group elements other than noble gases are the elements of Groups 1, 2, and 12 to 17. Including the case where its content is 0. The content of each main group element other than oxygen, hydrogen, and argon in the transition metal oxide film is preferably less than 1.0 at%, more preferably 0.5 at% or less, and further preferably 0.1 at% or less.

[0065] The total content of all impurities other than transition metal T, oxygen, hydrogen, and impurity A is preferably less than 1.0 at%. In other words, the sum of the content of transition metal T (J), oxygen (K), hydrogen (L), and impurity A (M) is preferably greater than 99.0 at% (J+K+L+M>99.0 at%). The total content of all impurities other than transition metal T, oxygen, hydrogen, and impurity A is more preferably 0.5 at% or less. In other words, the sum of the content of transition metal T (J), oxygen (K), hydrogen (L), and impurity A (M) is preferably 99.5 at% or more (J+K+L+M) ≥ 99.5% (at%). The total content of all impurities other than transition metal T, oxygen, hydrogen, impurity A, and impurity B is preferably 0.1 at% or less. In other words, the sum of the content of transition metal T (J), oxygen (K), hydrogen (L), impurity A (M), and impurity B (N) is preferably 99.9 at% or more (J+K+L+M+N≥99.9 at%). In transition metal oxide films, the content of all elements except transition metal T, oxygen, impurity A, and impurity B can be below the detection limit. Transition metal oxide films do not necessarily include elements other than transition metal T, oxygen, hydrogen, impurity A, and impurity B.

[0066] The contents of transition metal T (J) (at%), oxygen (K) (at%), hydrogen (L) (at%), impurity A (M) (at%), and impurity B (N) (at%) satisfy at least one of the following: J+K>L+M+N, J>L, K>L, L>M, and M>N. Furthermore, L≥1.0at%, N<1.0at%, and J+K+L+M≥99.0at% are also valid.

[0067] When the approximations K / J≈k / j and J+K+L≈100 are applied to the stoichiometric composition T of transition metal oxides j O kWhen L < j, L < 100×j / (2×j + k) holds when L < 100×j / (2×j + k), and L ≤ 100×j / (3×j + 2×k) holds when L ≤ J / 2. When j = 1 and k = 2, L < 25 at% is required to satisfy L < 100×j / (2×j + k). When j = 1 and k = 3, L < 14 at% is required to satisfy L < 100×j / (2×j + k). When j = 2 and k = 3, L < 28 at% is required to satisfy L < 100×j / (2×j + k). When j = 2 and k = 5, L < 22 at% is required to satisfy L < 100×j / (2×j + k). When j = 1 and k = 2, L ≤ 14 at% is required to satisfy L ≤ 100×j / (3×j + 2×k). When j = 1 and k = 3, L ≤ 11 at% is required to satisfy L ≤ 100×j(3×j + 2×k). When j = 2 and k = 3, L ≤ 16.0 at% is required to satisfy L ≤ 100×j / (3×j + 2×k). When j = 2 and k = 5, L ≤ 12 at% is required to satisfy L ≤ 100×j / (3×j + 2×k).

[0068] Such transition metal oxide films can be used as optical films. An optical film is a film that utilizes the action of light, and examples of the action of light include reflection, transmission, absorption, refraction, scattering, and excitation. Since the amorphous film contains more than 1.0 at% hydrogen, the refractive index and extinction coefficient (absorptivity) of the film for a specific wavelength can be significantly controlled. Any transition metal oxide can be used for the optical film as long as the transition metal oxide can be used optically, and typically, oxides of transition metals in Groups 3 - 6 can be used. Oxides of transition metals in Groups 4 and 5 are particularly preferred. In addition, typically, oxides of transition metals in Periods 4 - 6 can be used. Oxides of transition metals in Periods 5 and 6 are particularly preferred.

[0069] The wavelength λ included in the light for the optical film is a wavelength at which the optical properties of the film can be significantly changed according to the hydrogen content of the film. The wavelength λ can be in the ultraviolet region (less than 400 nm), the visible region (400 nm to 800 nm), or the infrared region (greater than 800 nm). The light for the optical film can include light of wavelengths at which the optical properties of the film do not change significantly according to the hydrogen content of the film.

[0070] Optical elements, including optical films, can be those whose optical properties remain unchanged by external forces, or those whose optical properties change due to external forces. In the former case, the optical element is a lens, mirror, or filter, and the optical film can be used as an anti-reflective film, a reflective film, or a light-absorbing film. In the latter case, the optical element can be a color-changing element, for example, utilizing the color-changing properties of the optical film. For example, tungsten oxide, molybdenum oxide, titanium oxide, chromium oxide, cobalt oxide, and nickel oxide can have color-changing properties. Examples of external forces acting on color-changing elements include electrochromic (electrochromic) and chemical (gas-chromic) effects.

[0071] Optical elements comprising optical films constitute optical devices. In addition to optical elements comprising optical films, the optical device may also include a light source that emits light onto the optical film. In optical devices that include a light source emitting light of a specific wavelength λ, the characteristics of the optical film of the optical element can be adjusted according to the wavelength λ by adjusting the hydrogen content L.

[0072] Of course, the light used for optical films can be light emanating from outside the optical device.

[0073] The optical film (i.e., the transition metal oxide film) of the optical element constitutes part or all of the optical structure on the substrate. When the transition metal oxide film constitutes the entire optical structure on the substrate, the optical structure is a monolayer of the transition metal oxide film. When the transition metal oxide film constitutes part of the optical structure on the substrate, the optical structure on the substrate is a stack comprising multiple transition metal oxide films. Typically, the optical structure is a stack of transition metal oxide films and different optical films. The different optical films stacked with the transition metal oxide film can have a higher or lower refractive index than the transition metal oxide film. Since the transition metal oxide film has a relatively high refractive index, it is preferably used as a high refractive index film, and the different optical films stacked with the transition metal oxide film are low refractive index films with a lower refractive index than the transition metal oxide film. The different optical films stacked with the transition metal oxide film can be oxide films of main group elements. In this embodiment, the refractive index of the transition metal oxide film can be adjusted by adjusting the hydrogen content of the transition metal oxide film.

[0074] The transition metal oxide film of this embodiment is suitable for optical films in which multiple transition metal oxide films and different optical films are alternately stacked. Here, alternating stacking of first-type films and second-type films means that at least one second-type film is located between two first-type films, and at least one first-type film is located between two second-type films. Therefore, at least four films are required to alternately stack the first-type and second-type films. In the optical structure in which multiple transition metal oxide films and different optical films are alternately stacked, the number of layers of the multiple transition metal oxide films needs to be 2 or more, but can be 3 or more, 10 or more, 20 or more, 30 or more, or 40 or more. The more layers of transition metal oxide films provided in the optical structure, the stronger the effect of controlling the optical properties of the transition metal oxide films in the optical structure by adjusting the hydrogen content.

[0075] Although oxide films, fluoride films, and other similar membranes are used in contact with transition metal oxide films, oxide films are preferred due to their adhesion to transition metal oxide films. In a structure where a transition metal oxide film is disposed between a first oxide film and a second oxide film, the lower surface of the transition metal oxide film is in contact with the first oxide film, and the upper surface of the transition metal oxide film is preferably in contact with the second oxide film because transition metal oxide films have high adhesion and stability. Examples of oxide films in contact with transition metal oxide films include oxide films of main group elements, such as silicon oxide films, aluminum oxide films, magnesium oxide films, and zinc oxide films. That is, in a structure where transition element oxide films and main group element oxide films are alternately stacked, the properties of the transition element oxide films can be tuned by adjusting the hydrogen content.

[0076] Films containing amorphous transition metal oxides as the main component, with a hydrogen content of 1.0 at% or more and a total content of transition metals, oxygen, hydrogen and argon exceeding 99.0 at%, contain a small amount of impurities. Therefore, they are suitable not only for optical films but also for insulating films used in electrical applications.

[0077] An electronic component may include a first portion serving as an electrode, a second portion serving as a semiconductor layer or electrode, and an amorphous transition metal oxide film. To insulate the first portion as an electrode from the second portion serving as a semiconductor layer or electrode, an amorphous transition metal oxide film may be disposed between the first portion as an electrode and the second portion serving as a semiconductor layer or electrode. In the case of a transistor, the first portion may be a gate electrode, the amorphous transition metal oxide film may be a gate insulating film, and the second portion may be a semiconductor layer. The electronic component may be a capacitor with a metal-oxide-semiconductor (MOS) structure or a capacitor with a metal-oxide-metal (MOM) structure.

[0078] Reactive sputtering is useful for forming transition metal oxide films containing a large amount of hydrogen (1.0 at%) or more. A hydrogen-containing transition metal oxide film can be formed by generating a plasma in an atmosphere containing oxygen, hydrogen, and argon, sputtering a transition metal target with argon, and reacting the sputtered metal with oxygen and hydrogen. The crystallinity of the transition metal oxide film can then be controlled by adjusting the amount of oxygen. For example, the transition metal oxide film is more likely to be crystalline with a higher oxygen content and more likely to be amorphous with a lower oxygen content. Furthermore, the crystallinity of the transition metal oxide film can be controlled by adjusting the sputtering power, atmosphere pressure, substrate temperature, and the positional relationship between the target and substrate during film formation. For example, the transition metal oxide film is more likely to be amorphous at higher sputtering power or higher sputtering atmosphere pressure. Additionally, amorphization is also facilitated by increasing the distance between the target and substrate in a direction perpendicular to the film formation surface of the substrate, and by moving the target and substrate horizontally to the film formation surface of the substrate. However, even if any of the above conditions favorable to amorphization are met, crystallization can still occur, depending on the degree of other parameters; therefore, appropriate condition settings are required for amorphization. The hydrogen content of the transition metal oxide film can be controlled by adjusting the amount of hydrogen. For example, decreasing the amount of hydrogen results in a lower hydrogen content, while increasing the amount of hydrogen results in a higher hydrogen content. Impurity A can originate from gases in the film-forming atmosphere, such as argon, while impurity B can originate from impurities in the target. Other impurities can be metallic elements contained in the film-forming apparatus, or carbon, nitrogen, and fluorine adhering to the sputtering target or mixed in the film-forming gas. By minimizing these impurities, high-quality films can be obtained.

[0079] The following describes embodiments using hafnium oxide as a transition metal oxide as a first embodiment and a second embodiment. Hafnium oxide has a high refractive index and a high dielectric constant, and therefore its application in the fields of optical components and semiconductor components is considered.

[0080] In the field of optical components, attempts are being made to use hafnium oxide films as optical coatings for optical parts such as lenses or filters. As performance standards for optical equipment increase, the number of optical components used in these devices is also increasing, leading to a growing trend in the number of optical surfaces requiring optical film coating. Furthermore, the optical films used for coating are not necessarily single-layered and can, in some cases, consist of multiple layers, thus increasing the total number of layers.

[0081] In these cases, for example, the optical surfaces of exposure devices such as semiconductor manufacturing apparatuses that use ultraviolet wavelengths (such as i-line and h-line) can be coated with hafnium oxide as a high refractive index material, in which bandgap absorption in the ultraviolet region is impossible.

[0082] In the field of optical components, there is a desire to realize optical films containing hafnium oxide, with a good balance of high refractive index and low light absorption, and high performance.

[0083] In the field of semiconductor devices, there is a desire to realize a gate insulating film containing hafnium oxide, with a good balance of high dielectric constant and low leakage current, and high performance.

[0084] Therefore, from the viewpoint of the first and second embodiments, it is intended to provide a technology that facilitates the achievement of high performance of hafnium oxide-containing membranes.

[0085] One embodiment of the first and second embodiments is a membrane containing amorphous hafnium oxide as the main component, with a hydrogen content of 1.0 at% or more.

[0086] According to the first and second embodiments, by achieving a good balance between high refractive index and low absorption, and a good balance between high dielectric constant and low leakage current, it is possible to provide a technique that facilitates high performance in films containing hafnium oxide.

[0087] The hafnium oxide membrane and the apparatus including the membrane, as embodiments of the present invention, will be described with reference to the accompanying drawings.

[0088] First Implementation Plan

[0089] Optical components

[0090] Figure 1 This is a schematic cross-sectional view of an optical element according to this embodiment. The optical element 100 includes a substrate 101 and an optical structure 102 formed on the substrate 101. In the optical structure 102, a high-refractive-index layer 102a formed of a high-refractive-index material and a low-refractive-index layer 102b formed of a low-refractive-index material are alternately stacked. The optical structure 102 may also be referred to as a multilayer film. Here, alternating stacking of first-type and second-type layers means that at least one second-type layer is located between two first-type layers, and at least one first-type layer is located between two second-type layers. Therefore, at least four layers are required to alternately stack the first-type and second-type layers.

[0091] The substrate 101 can be made of materials such as calcium fluoride crystal, quartz glass, optical glass such as borosilicate crown glass BK7, resin, or metal. In addition, the substrate 101 can be of various shapes, such as planar or curved, depending on the application and type of optical elements such as lenses, mirrors, filters, and prisms.

[0092] The material used as the main component of the high refractive index layer 102a is hydrogen-containing amorphous hafnium oxide (HfO2), the details of which will be described later. It should be noted that in the following description, a film containing hafnium oxide (HfO2) as the main component is also described as a hafnium oxide film in some cases. It should be noted that a film containing hafnium oxide as the main component means that the sum of the hafnium content J (at%) and the oxygen content K (at%) in the hafnium oxide film is greater than the respective contents L (at%), M (at%), and N (at%) of each element other than hafnium and oxygen (J + K > L, J + K > M, and J + K > N). Although in the hafnium oxide film, J + K is 100 at% or less, since the hafnium oxide film of the present embodiment contains elements other than hafnium and oxygen, such as hydrogen, J + K is less than 100 at%. According to the stoichiometric composition HfO2, typically J < K < 3×J holds. The hafnium content J is in the range of, for example, 20 at% to 50 at%, and the oxygen content K is in the range of, for example, 50 at% to 80 at%. The sum of the hafnium content J (at%) and the oxygen content K (at%) in the hafnium oxide film is preferably greater than the sum of the contents L (at%), M (at%), and N (at%) of all elements other than hafnium and oxygen contained in the hafnium oxide film (J + K > L + M + N). In this case, J + K is higher than 50 at%. Although the case of providing three elements other than hafnium and oxygen is described as an example herein, the number of elements other than hafnium and oxygen can be one, two, four, or more.

[0093] Examples of materials for the low refractive index layer 102b include materials containing silicon oxide or aluminum oxide as the main component, but the structure is not limited thereto. For example, MgF2, CaF 2, LaF3, CeF3, YF3, etc. can be used.

[0094] As Figure 1As shown, the optical structure 102 has a configuration in which a high-refractive-index layer 102a and a low-refractive-index layer 102b are alternately stacked from the substrate 101 side, with the outermost layer being the low-refractive-index layer 102b. It should be noted that this configuration can be varied depending on the application of the optical element. For example, it may also have a configuration in which the low-refractive-index layer 102b and the high-refractive-index layer 102a are alternately stacked from the substrate 101 side, with the outermost layer being the low-refractive-index layer 102b. Furthermore, a protective layer can be provided on the outermost low-refractive-index layer 102b to form the outermost layer, an intermediate refractive-index layer formed of a material with an intermediate refractive index can be disposed between the high-refractive-index layer 102a and the low-refractive-index layer 102b, and an adhesive layer can be provided between the substrate 101 and the optical structure 102. It should be noted that the optical structure 102 does not necessarily have an alternating stacked structure of low-refractive-index layer 102b and high-refractive-index layer 102a. Furthermore, the optical structure 102 does not necessarily have a multilayer structure including a high refractive index layer 102a and a low refractive index layer 102b, and can have a single-layer structure including only one high refractive index layer 102a.

[0095] Manufacturing method

[0096] A method for manufacturing an optical element as an optical component according to this embodiment will be described, the optical element comprising a hydrogen-containing amorphous hafnium oxide film as a high-refractive-index layer. Alternatively, a known film-forming method can be used to form a low-refractive-index layer 102b, therefore its description will be omitted.

[0097] Figure 2 This is a schematic diagram of a sputtering film deposition apparatus 200 for manufacturing optical components. The sputtering film deposition apparatus 200 includes a vacuum chamber 201 serving as a gas-tight container, and an exhaust system 202 for venting air from the vacuum chamber 201. Furthermore, the sputtering film deposition apparatus 200 includes an argon inlet 204, an oxygen inlet 205, and a hydrogen inlet 206, thereby allowing the gases required for film deposition to be introduced into the vacuum chamber 201. Additionally, a sputtering target 210, a backplate 211, a magnet mechanism 207, and a substrate holding mechanism 208 are provided into the vacuum chamber 201. By holding the substrate 101 of the optical component in the substrate holding mechanism 208 and supplying it with power from a power source 203, film deposition can be performed using reactive sputtering.

[0098] To form a hydrogen-containing amorphous hafnium oxide film as a high refractive index layer, a film is deposited by reactive sputtering according to the following steps. For example, a substrate 101 made of quartz glass processed into a predetermined optical element shape and an 8-inch metallic hafnium with a purity of 99.9 wt% or higher, serving as a sputtering target 210, are placed in a vacuum chamber 201. At this time, the distance between the substrate 101 and the sputtering target 210 is set to, for example, 125 mm. Furthermore, the air in the vacuum chamber 201 is exhausted by an exhaust system 202 to achieve approximately 5 × 10⁻⁶ m³ / s. -5A vacuum level of Pa is achieved. Then, plasma discharge is performed simultaneously by introducing argon gas through argon inlet 204, oxygen gas through oxygen inlet 205, and hydrogen gas through hydrogen inlet 206. That is, plasma discharge is achieved by applying 50 W / cm² to the sputtering target 210 from the power supply 203. 2 The power is used to generate plasma discharge, and a hydrogen-containing amorphous hafnium oxide film of about 100 nm thickness is formed on a substrate 101, for example, with a diameter of 30 mm and a thickness of 1 mm. It should be noted that the thickness of each layer is not necessarily limited to about 100 nm, and is appropriately set according to the wavelength of the light used in the optical element and the number of layers constituting the optical structure. The thickness of the hafnium oxide film in the optical element is, for example, in the range of 10 nm to 1000 nm, or in the range of 10 nm to 100 nm. A hafnium oxide layer with a thickness of 100 nm can be stacked to form a hafnium oxide film with a thickness of 1000 nm. Specific embodiments and comparative examples will be described below.

[0099] Examples 1 to 4 and Comparative Examples 1 and 2

[0100] The high refractive index layer for optical structures will be described with reference to Examples 1 to 4 and Comparative Examples 1 and 2. The high refractive index layer according to Examples 1 to 4 and Comparative Example 2 was formed when oxygen was introduced through oxygen inlet 205 at a flow rate of 20 sccm. Furthermore, the high refractive index layer according to Comparative Example 1 was formed when oxygen was introduced through oxygen inlet 205 at a flow rate of 60 sccm. In all examples and comparative examples, argon gas was introduced from argon inlet 204 at a flow rate of 60 sccm to form the film. Additionally, in Example 1, plasma discharge was performed when hydrogen gas was introduced through hydrogen inlet 206 at a flow rate of 30 sccm. In other examples and comparative examples, as described below, the amount of hydrogen contained in the film was adjusted by changing the hydrogen flow rate from Example 1. It should be noted that the above conditions are merely examples and can be changed depending on the structure of the film-forming apparatus, etc. Generally, when the oxygen flow rate introduced into the chamber increases, the film quality tends to be closer to a crystalline state than an amorphous state, while when the hydrogen flow rate increases, the amount of hydrogen contained in the film tends to increase. It is believed that when the oxygen flow rate increases, more negative oxygen ions are generated in the chamber, thus increasing the energy applied to the matrix and promoting crystallization.

[0101] For single hafnium oxide films of each embodiment and each comparative example, crystallinity, hydrogen content, light absorption rate, and refractive index were evaluated.

[0102] Crystallinity was evaluated using X-ray diffraction analysis. In the following description, amorphous refers to a state where no obvious diffraction peaks were detected when X-rays were incident on the film being measured at a small angle of approximately 0.5° and a diffraction pattern was observed; in other words, a halo pattern was observed. Therefore, the amorphous state described herein does not necessarily exclude the inclusion of microcrystalline materials. For example, Figure 7 The X-ray diffraction pattern (incident angle: 0.4°) of the hafnium oxide film of Example 1 is shown, in which only a halo pattern is observed, no obvious crystal peaks are observed, and the film quality of Example 1 can be determined to be amorphous. Furthermore, for example, Figure 8 The X-ray diffraction pattern (incident angle: 0.4°) of the hafnium oxide film of Comparative Example 1 is shown, in which obvious crystallization peaks can be observed, and the film quality of Comparative Example 1 can be determined to be crystalline. The crystallinity of other examples and comparative examples was also evaluated using similar standards.

[0103] Furthermore, the hydrogen content of the hafnium oxide film was evaluated by irradiating it with a MeV-level high-energy ion beam and performing elastic recoil detection analysis (ERDA). Other materials in the film besides hydrogen were evaluated by irradiating the film with a MeV-level high-energy ion beam and performing Rutherford backscattering spectroscopy (RBS). The hydrogen content (at%) of the hafnium oxide film was obtained using these results.

[0104] In addition, light absorptivity and refractive index were evaluated by measuring transmittance and reflectance at a beam incident angle of 5° in the wavelength range of 200 nm to 500 nm using an ultraviolet-visible-near-infrared spectrometer.

[0105] The light absorption rate is calculated using the following formula.

[0106] A(%) = 100 - T(%) - R(%) (Equation 1)

[0107] In this formula, A(%) represents light absorption rate, T(%) represents transmittance, and R(%) represents reflectance.

[0108] Using Film Wizard, an optical thin film analysis / design software available from Scientific Computing International. TM The refractive index is calculated by analyzing the measured reflectance.

[0109] Light with a wavelength of 280 nm is used as a standard to evaluate light absorptivity and refractive index, thereby assessing the suitability of optical elements for exposure apparatuses (semiconductor manufacturing apparatuses) that utilize wavelengths in the ultraviolet region, such as i-lines and h-lines. Of course, in the case of optical elements for different applications, evaluation can be performed using wavelengths suitable for those applications. The wavelengths suitable for optical elements are not limited to the ultraviolet region; they can also be wavelengths in the visible or infrared regions.

[0110] Table 1 shows the evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2.

[0111] Table 1

[0112] Crystallinity hydrogen content Absorption rate Refractive index Example 1 amorphous state 6.5 at% 0.08％ 2.253 Example 2 amorphous state 15.8 at% 0.04％ 2.225 Example 3 amorphous state 1.0at% 0.77％ 2.260 Example 4 amorphous state 17.0 at% 0.06％ 2.031 Comparative Example 1 Crystalline 0at% 3.43％ 2.171 Comparative Example 2 amorphous state 0at% 0.80％ 2.262

[0113] Regarding the crystallinity of the hafnium oxide film in Example 1, the hafnium oxide film is amorphous, and the hydrogen content in the hafnium oxide film is 6.5 at%. Furthermore, the hafnium oxide film of Example 1 has an absorption rate of 0.08% for light at a wavelength of 280 nm, and a refractive index of 2.253 for a wavelength of 280 nm.

[0114] Regarding the crystallinity of the hafnium oxide film in Example 2, the hafnium oxide film is amorphous, and the hydrogen content in the hafnium oxide film is 15.8 at%. Furthermore, the hafnium oxide film of Example 2 has an absorption rate of 0.04% for light at a wavelength of 280 nm, and a refractive index of 2.225 for a wavelength of 280 nm.

[0115] Regarding the crystallinity of the hafnium oxide film in Example 3, the hafnium oxide film is amorphous, and the hydrogen content in the hafnium oxide film is 1.0 at%. Furthermore, the hafnium oxide film of Example 3 has an absorption rate of 0.77% for light at a wavelength of 280 nm, and a refractive index of 2.260 for a wavelength of 280 nm.

[0116] Regarding the crystallinity of the hafnium oxide film in another embodiment using film-forming conditions between Examples 1 and 3, the hafnium oxide film is amorphous, and the hydrogen content in the hafnium oxide film is 3.8 at%. Furthermore, the hafnium oxide film has an absorption rate of 0.61% for light at a wavelength of 280 nm, and a refractive index of 2.252 for a wavelength of 280 nm.

[0117] Regarding the crystallinity of the hafnium oxide film in Example 4, the hafnium oxide film is amorphous, and the hydrogen content in the hafnium oxide film is 17.0 at%. Furthermore, the hafnium oxide film in Example 4 has an absorption rate of 0.06% for light at a wavelength of 280 nm, and a refractive index of 2.031 for a wavelength of 280 nm.

[0118] Regarding the crystallinity of the hafnium oxide film in Comparative Example 1, the hafnium oxide film is crystalline, and the hydrogen content in the hafnium oxide film is 0 at%. Furthermore, the hafnium oxide film of Comparative Example 1 has an absorption rate of 3.43% for light at a wavelength of 280 nm, and a refractive index of 2.171 for a wavelength of 280 nm.

[0119] Regarding the crystallinity of the hafnium oxide film in Comparative Example 2, the hafnium oxide film is amorphous, and the hydrogen content in the hafnium oxide film is 0 at%. Furthermore, the hafnium oxide film of Comparative Example 2 has an absorption rate of 0.80% for light at a wavelength of 280 nm, and a refractive index of 2.262 for a wavelength of 280 nm.

[0120] Regarding the crystallinity of the hafnium oxide film in the reference example, where the hydrogen flow rate was increased compared to Comparative Example 1, the hafnium oxide film is crystalline, and the hydrogen content of the hafnium oxide film is 7.5 at%. Furthermore, the hafnium oxide film of the reference example has an absorbance of 0.53% for light at a wavelength of 280 nm, and a refractive index of 2.205 for a wavelength of 280 nm.

[0121] Comparing Comparative Examples 1 and 2, which are essentially free of hydrogen, the amorphous Comparative Example 2 has a higher refractive index and lower light absorption than the crystalline Comparative Example 1. Comparing Example 1 and a reference example with a hydrogen content in the range of 6 at% to 8 at%, the amorphous Example 1 has a higher refractive index and lower light absorption than the crystalline reference example. Examples 1 to 4, with hydrogen content higher than the amorphous Comparative Example 2, have lower light absorption than Comparative Example 2. The reference examples with hydrogen content higher than the crystalline Comparative Example 1 have lower light absorption and higher refractive index than Comparative Example 1. For light absorption, the first objective is less than 1.0%, a more preferred second objective is less than 0.5%, and a more preferred third objective is less than 0.2%. For refractive index, the first objective is 2.10 or higher, a more preferred second objective is 2.15 or higher, and a more preferred third objective is 2.20 or higher. As can be seen from Example 4, even when the hydrogen content exceeds 17%, the refractive index decreases to 2.031, even if the film quality is amorphous. Furthermore, as can be seen from Comparative Example 1, when the membrane quality is crystalline and the membrane is essentially free of hydrogen, the light absorption rate is as high as 3.43%.

[0122] As mentioned above, the absorptivity and refractive index in amorphous films may vary more with hydrogen content than in crystalline films. Therefore, by setting the hydrogen content to 1 at% or more, the absorptivity and refractive index in amorphous films can be significantly controlled. It should be noted that a hydrogen content of 1 at% or more includes cases where the hydrogen content is 1.0 at%, as in Example 3, and includes cases where the hydrogen content is 1.0 at% or more.

[0123] As can be seen from the above, amorphous hafnium oxide films containing 1 at% to 16 at% hydrogen are suitable for high-performance optical films, in which a high refractive index and a low light absorption rate are achieved with a good balance. In particular, hafnium oxide films containing 6.5 at% to 15.8 at% hydrogen are preferred because a high refractive index of more than 2.22 and an extremely low light absorption rate of less than 0.1% (0.08% or less) can be achieved simultaneously. It should be noted that for the hafnium oxide films of the present embodiment, it is not necessary to actively add silicon to the hafnium oxide films, and the silicon content O in the hafnium oxide films is preferably lower than the hydrogen content L (O < L). The silicon content O of the hafnium oxide films described in the above examples is less than 1 at%, 0.1 at% or less, or less than the detection limit. In the case of hafnium oxide films added with silicon, adding silicon can not only reduce the refractive index, but the light absorption is not necessarily sufficiently suppressed. For example, in hafnium oxide films added with 1 at% to 10 at% silicon, it is possible to suppress the transmission loss of each film to less than 1%. However, for example, in the case where 40 surfaces are coated, the loss can accumulate to more than 10%, which is not necessarily sufficient for optical performance. In the hafnium oxide films of the present embodiment, it is not necessary to actively add carbon to the hafnium oxide films, and the carbon content P in the hafnium oxide films is preferably less than the hydrogen content L (P < L). The carbon content P of the hafnium oxide films described in the above examples is less than 1 at%, 0.1 at% or less, or less than the detection limit. In the hafnium oxide films of the present embodiment, it is not necessary to actively add nitrogen to the hafnium oxide films, and the nitrogen content Q of the hafnium oxide films is preferably less than the hydrogen content L (Q < L). The nitrogen content Q of the hafnium oxide films described in the above examples is less than 1 at%, 0.1 at% or less, or less than the detection limit.

[0124] In addition, the hafnium oxide film of the present embodiment may also contain elements other than hafnium, oxygen, and hydrogen. For example, the hafnium oxide film described in the above embodiments may contain argon. This argon is derived from the argon gas introduced through the argon gas inlet 204 during film formation. The argon content M in the hafnium oxide film is preferably less than the hydrogen content L (M < L). The argon content M in the hafnium oxide film is in the range of, for example, 0.5 at% to 5 at%. The hafnium oxide film described in the above embodiments may contain zirconium. This zirconium is derived from the sputtering target 210 used for film formation. The zirconium content N in the hafnium oxide film is preferably less than the hydrogen content L (N < L). The zirconium content N in the hafnium oxide film is in the range of, for example, 0.05 at% to 0.5 at%. The zirconium content N is preferably less than the argon content M (N < M). The silicon content O in the hafnium oxide film is preferably lower than the argon content M (O < M). The silicon content O in the hafnium oxide film is preferably lower than the zirconium content N (O < N). Even when the film contains argon or zirconium, the present embodiment can achieve a high refractive index and low light absorption. In the hafnium oxide films of the above Examples 1-4 and Comparative Examples 1 and 2, the content of elements other than hafnium, oxygen, hydrogen, argon, and zirconium is below the detection limit. The zirconium content N in Examples 1-4 is in the range of 0.2-0.3 at%. Therefore, the sum (J + K + L + M) of the hafnium content J, oxygen content K, hydrogen content L, and argon content M is in the range of 99.7 to 99.8 at%. In Examples 1-4, the hafnium content J is in the range of 25-33 at%, the oxygen content K is in the range of 50-66 at%, and the argon content M is in the range of 1-2 at%. The ratio (K / M) of the oxygen content K to the hafnium content M is greater than 2.00 and less than 2.10 (2.00 < K / M < 2.10). In Examples 1, 2, and 4 where the hydrogen content L exceeds 2 at%, the hydrogen content L is greater than the argon content M (L > M).

[0125] For reference, Figure 3 a coordinate diagram showing the light absorption characteristics with respect to the hydrogen content, Figure 4 a coordinate diagram showing the refractive index characteristics with respect to the hydrogen content is shown. In addition, Figure 5 the wavelength dependence of the light absorption of Examples 1 and 3 is shown, Figure 6 the wavelength dependence of the refractive index of Examples 1 and 4 is shown.

[0126] From Figure 3 it can be speculated that the absorption rate of amorphous hafnium oxide with a hydrogen content of 5 at% or more can be suppressed to less than half of the absorption rate in the case of a hydrogen content of 0 at%. As Figure 3 shown, the absorption rate of amorphous hafnium oxide with a hydrogen content of 6 at% or more is 0.1% or less, which is low enough. As Figure 5 shown, especially in Example 1, the absorption rate is very low in the wavelength range below 400 nm. In addition, as Figure 4As shown, a high refractive index can be maintained in the range of hydrogen content below 16 at%. The inventors employed a model in which hydrogen fills the oxygen vacancies generated in the hydrogen-containing hafnium oxide. When the stoichiometric composition of hafnium oxide with a hydrogen content of 0 at% is assumed to be HfO2, the hydrogen-containing hafnium oxide can be modeled as HfO. 2-x H x The hydrogen concentration calculated using this model, with a hydrogen content of 1 at%, is approximately 1 × 10⁻⁶. 21 atoms / cm 3 With a hydrogen content of 5 at%, it is approximately 5 × 10⁻⁶. 21 atoms / cm 3 With a hydrogen content of 6 at%, it is approximately 6 × 10⁻⁶. 21 atoms / cm 3 With a hydrogen content of 10 at%, it is approximately 1 × 10⁻⁶. 22 atoms / cm 3 With a hydrogen content of 16 at%, it is approximately 1.6 × 10⁻⁶. 22 atoms / cm 3 And with a hydrogen content of 20 at%, it is approximately 2 × 10⁻⁶. 22 atoms / cm 3 The hydrogen concentration of the hafnium oxide film in this embodiment can be 1×10⁻⁶. 21 atoms / cm 3 Up to 2×10 22 atoms / cm 3 Within a certain range. Preferably in terms of atoms / cm 3 The indicated hydrogen concentration range satisfies an appropriate hydrogen content (at%). Furthermore, the hydrogen concentration of the hafnium oxide film in this embodiment can be 5 × 10⁻⁶. 21 atoms / cm 3 Above, 6×10 21 atoms / cm 3 The above, and 1.6×10 22 atoms / cm 3 Below. However, depending on the content of impurities such as argon and zirconium, and the packing density of the hafnium oxide film, in quantities less than 1×10... 21 atoms / cm 3 Within the hydrogen concentration range, it can meet the requirements of 1 at% to 16 at% or 6 at% to 16 at% hydrogen content, and is greater than 1×10 21 atoms / cm 3 Within the hydrogen concentration range, it can meet the requirements of 1 at% to 16 at% or 6 at% to 16 at% hydrogen content. (The last part, "greater than 2 × 10," appears to be an unrelated fragment and is omitted from the translation.) 22 atoms / cm 3 Within the hydrogen concentration range, it can meet the requirements of 1at% to 16at% or 6at% to 16at% hydrogen content.

[0127] It is speculated that the reason for improving light absorption by including hydrogen in hafnium oxide is that lattice defects, which are the main cause of light absorption degradation, are fixed by hydrogen. Furthermore, although the reason for the rapid decrease in refractive index after the hydrogen content exceeds 16 at%, it is speculated that this is because hydrogen enters not only the lattice defects of hafnium oxide but also the lattice itself, thus degrading the stacking of hafnium oxide. Moreover, it is speculated that even with the inclusion of hydrogen, the light absorption of crystallized hafnium oxide is not sufficiently improved because energy levels originating from the crystal are formed in the band gap, which induces new light absorption.

[0128] Examples 5 and 6

[0129] Specific examples of forming an optical structure as an antireflection structure on the surface of a transmissive optical element will be described. As Example 5, an optical structure as an antireflection structure is formed in which an amorphous hafnium oxide film containing 6.5 at% hydrogen, as a high-refractive-index film as described in Example 1, and a low-refractive-index film are alternately stacked. Furthermore, as Example 6, an optical structure as an antireflection structure is formed in which an amorphous hafnium oxide film containing 17.0 at% hydrogen, as a high-refractive-index film as described in Example 4, and a low-refractive-index film are alternately stacked.

[0130] Figure 9 These are cross-sectional views of the layer structures in Examples 5 and 6. In the optical element 900, a high-refractive-index layer 902a formed of a high-refractive-index material and a low-refractive-index layer 902b formed of a low-refractive-index material (four layers in total) are alternately stacked on a quartz substrate 901, which serves as the substrate, thereby constituting an optical structure 902. The low-refractive-index layer 902b is formed of silicon oxide. Considering the intended use of the optical element 900, based on the refractive index values ​​for a wavelength of 280 nm in Examples 1 and 4, the construction of the optical structure is determined by optimizing the physical film thickness of each layer to maximize the anti-reflection characteristics in the wavelength range of 280 nm to 400 nm.

[0131] Table 2 shows the specifications of each layer in Example 5.

[0132] Table 2

[0133] Material Refractive index Physical film thickness (nm) Fourth floor silicon dioxide 1.506 53.02 Third layer Hafnium oxide (*1) 2.253 50.13 Second floor silicon dioxide 1.506 15.08 First layer Hafnium oxide (*1) 2.253 12.62 matrix Quartz glass 1.489 -

[0134] (*1) Amorphous state; Hydrogen content: 6.5 at%

[0135] Table 3 shows the specifications of each layer in Example 6.

[0136] Table 3

[0137] Material Refractive index Physical film thickness (nm) Fourth floor silicon dioxide 1.506 55.68 Third layer Hafnium oxide (*2) 2.031 47.01 Second floor silicon dioxide 1.506 19.76 First layer Hafnium oxide (*2) 2.031 12.94 matrix Quartz glass 1.489 -

[0138] (*2) Amorphous state; Hydrogen content: 17.0 at%

[0139] Figure 10 The reflection characteristics of the optical structures of Examples 5 and 6 as antireflection structures are shown. In the wavelength range of 280 nm to 400 nm, Example 5, using an amorphous film with a hydrogen content of 6.5 at% and a high refractive index, achieves a lower reflectivity compared to Example 6, which uses an amorphous film with a hydrogen content of 17.0 at%. In Examples 5 and 6, the average reflectivity in this wavelength range is 0.10% and 0.33%, respectively. Furthermore, in the case of Example 5, the reflectivity is 0.25% or less at any wavelength in the wavelength range of 290 nm to 385 nm, thus obtaining very good antireflection characteristics.

[0140] Examples 7 and 8

[0141] Specific examples of forming an optical structure as a reflective structure on the surface of a reflective optical element will be described. As Example 7, an optical structure as a reflective structure is formed in which an amorphous hafnium oxide film containing 6.5 at% hydrogen, as a high-refractive-index film as described in Example 1, and a low-refractive-index film are alternately stacked. Furthermore, as Example 8, an optical structure as a reflective structure is formed in which an amorphous hafnium oxide film containing 17.0 at% hydrogen, as a high-refractive-index film as described in Example 4, and a low-refractive-index film are alternately stacked.

[0142] Figure 11 These are cross-sectional views of the layer structures in Examples 7 and 8, which differ from the antireflective structures in Examples 5 and 6. Specifically, a low-refractive-index layer 1002b formed of a low-refractive-index material and a high-refractive-index layer 1002a formed of a high-refractive-index material (a total of 5 layers) are alternately stacked on the substrate 1001 of the reflective optical element 1000 to form the optical structure 1002. The substrate 1001 in Examples 7 and 8 is made of aluminum, which is an aluminum film approximately 100 nm thick and coated on a glass plate. The aluminum substrate 1001 can be an aluminum plate. The low-refractive-index layer 1002b is formed of silicon oxide. Considering the intended use of the optical element 1000, the construction of the optical structure is determined by optimizing the physical film thickness of each layer based on the refractive index values ​​for a wavelength of 280 nm in Examples 1 and 4, so as to maximize the reflective characteristics in the wavelength range of 280 nm to 400 nm.

[0143] Table 4 shows the specifications of each layer in Example 7.

[0144] Table 4

[0145] Material Refractive index Physical film thickness (nm) Fifth floor silicon dioxide 1.506 44.11 Fourth floor Hafnium oxide (*1) 2.253 44.11 Third layer silicon dioxide 1.506 53.81 Second floor Hafnium oxide (*1) 2.253 28.49 First layer silicon dioxide 1.506 40.40 matrix aluminum 0.361 -

[0146] (*1) Amorphous state; Hydrogen content: 6.5 at%

[0147] Table 5 shows the specifications of each layer in Example 8.

[0148] Table 5

[0149] Material Refractive index Physical film thickness (nm) Fifth floor silicon dioxide 1.506 46.22 Fourth floor Hafnium oxide (*2) 2.031 46.22 Third layer silicon dioxide 1.506 56.88 Second floor Hafnium oxide (*2) 2.031 30.12 First layer silicon dioxide 1.506 42.70 matrix aluminum 0.361 -

[0150] (*2) Amorphous state; Hydrogen content: 17.0 at%

[0151] Figure 12 The reflective properties of the optical structures of Examples 7 and 8, which serve as reflective structures, are shown. In the wavelength range of 280 nm to 400 nm, Example 7, using an amorphous film with a hydrogen content of 6.5 at% and a high refractive index, achieves a higher reflectivity compared to Example 8, which uses an amorphous film with a hydrogen content of 17.0 at%. The average reflectivity in this wavelength range is 93.9% in Example 7 and 91.8% in Example 8. Furthermore, in the case of Example 7, the reflectivity is 93% or higher at any wavelength in the wavelength range of 290 nm to 380 nm, thus obtaining very good reflective properties.

[0152] Examples 9 and 10

[0153] Specific examples will be described whereby an optical structure, serving as an anti-reflection structure, is coated onto at least one lens in a lens group included in an exposure apparatus, which is a semiconductor manufacturing device. As Example 9, a lens group was manufactured in which the optical structure, serving as an anti-reflection structure, described in Example 5, is coated onto two surfaces (i.e., a total of 40 surfaces) of 20 lenses included in the exposure apparatus. That is, an optical structure serving as an anti-reflection structure is formed on the surface of each lens, wherein an amorphous hafnium oxide film containing 6.5 at% hydrogen, serving as a high-refractive-index layer, and a low-refractive-index layer are alternately stacked. Furthermore, as Example 10, a lens group was manufactured in which the optical structure, serving as an anti-reflection structure, described in Example 6, is coated onto two surfaces (i.e., a total of 40 surfaces) of 20 lenses included in the exposure apparatus. That is, an optical structure serving as an anti-reflection structure is formed on the surface of each lens, wherein an amorphous hafnium oxide film containing 17.0 at% hydrogen, serving as a high-refractive-index layer, and a low-refractive-index layer are alternately stacked.

[0154] For Examples 9 and 10, the suitability of the lens for an exposure apparatus including an ultraviolet light source was evaluated by measuring transmission loss using 280 nm ultraviolet light. Table 6 shows the results. Since the hafnium oxide film of the lens in the exposure apparatus including the ultraviolet light source is irradiated with ultraviolet light generated by the ultraviolet light source, the hafnium oxide film is irradiated with ultraviolet light in a similar manner. Furthermore, in the case of providing an infrared or visible light source, the suitability of the optical element can be evaluated by using light that irradiates the hafnium oxide film.

[0155] Table 6

[0156]

[0157] In the lens assembly of Example 9, achieving both low light absorption and low reflectivity on each surface significantly reduces transmission loss; therefore, the total transmission loss of the 40 surfaces of the lens can be suppressed to below 10%. In contrast, in Example 10, the reflectivity is significantly higher than in Example 9, resulting in a total transmission loss of over 10% across the 40 surfaces of the lens. It should be noted that the reason for the lower reflectivity of Example 10 compared to Example 9 can be attributed to the low refractive index of the hafnium oxide layer.

[0158] The lens group of Embodiment 9, when used as an illumination lens group or projection lens group in an exposure apparatus, has the effect of increasing the exposure intensity of the exposure apparatus, for example. Therefore, the exposure time can be shortened, and thus the processing performance of the exposure apparatus can be improved.

[0159] Second Implementation Plan

[0160] The second embodiment is an embodiment in which an amorphous hafnium oxide film containing hydrogen in the range of 1 at% to 16 at% is implemented in a semiconductor element.

[0161] In Examples 11 and 12, the hafnium oxide film described above is used as a gate insulating film (high-k gate insulating film) for a transistor. The hafnium oxide film, as a high-dielectric material film, can be formed using essentially the same apparatus and method as in the first embodiment, and the film thickness is set to a value suitable for the gate insulating film. The relationship between refractive index and dielectric constant can be obtained by considering electronic polarization and ionic polarization separately, and simultaneously by considering both electronic and ionic polarization. The dielectric constant calculated from the refractive index is the dielectric constant of electronic polarization, and the dielectric constant ε derived from electronic polarization is correlated with the refractive index n (ε...). 2 =n). A high refractive index implies a high dielectric constant due to electronic polarization. Since hafnium oxide is a material composed of ionic bonds, ionic polarization occurs in addition to electronic polarization when used in the presence of an electric field. When using hafnium oxide as a gate insulating film, both polarizations need to be considered to evaluate the dielectric constant. However, if the hydrogen content in hafnium oxide is set to 1 at% to 16 at%, the decrease in dielectric constant caused by electronic polarization can at least be suppressed. It should be noted that when forming a silicon-containing film by dispersing silicon in the hafnium oxide film, although it is possible to reduce the possibility of crystallization, the inclusion of silicon may also lead to a decrease in the dielectric constant.

[0162] In addition, in Embodiment 13, the hafnium oxide film described above can be provided as an anti-reflection structure on the light-receiving surface side of the camera element.

[0163] Example 11

[0164] Figure 13 This is a schematic cross-sectional view used to describe an example of a semiconductor device including a MOS transistor. Semiconductor device 130 includes an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) 131a and a p-channel MOSFET 131b formed in a semiconductor layer 133 such as n-type single-crystal silicon. The n-channel MOSFET 131a and p-channel MOSFET 131b constitute a complementary circuit (complementary metal-oxide-semiconductor CMOS circuit). An amorphous hafnium oxide film containing 1 at% to 16 at% hydrogen is used for the gate insulating film 132a of the n-channel MOSFET 131a and the gate insulating film 132b of the p-channel MOSFET 131b. The thickness of the gate insulating films 132a and 132b of the MOS transistor is typically 1 nm to 10 nm. Because the film is amorphous and contains a predetermined amount of hydrogen, the number of grain boundaries is very small, and a high dielectric constant can be achieved. Therefore, the MOS transistor including gate insulating films 132a and 132b according to this embodiment can significantly reduce leakage current.

[0165] It should be noted that the application of amorphous hafnium oxide films containing 1 at% to 16 at% hydrogen to the gate insulating film of MOSFETs is not limited to... Figure 13 Examples include the application of this film to the gate insulating film of a MOS transistor formed in a semiconductor layer such as p-type monocrystalline silicon, or to the gate insulating film of a single n-channel MOSFET or a single p-channel MOSFET, rather than complementary circuitry, to significantly reduce leakage current.

[0166] Example 12

[0167] Figure 14This is a schematic cross-sectional view used to describe an example of a semiconductor device including a thin-film transistor (TFT). The semiconductor device 140 includes a thin-film transistor formed on a glass substrate 141. The thin-film transistor includes: a semiconductor layer 143 such as low-temperature polycrystalline silicon, a source electrode 144, a drain electrode 145, a gate electrode 146, a gate insulating film 142, and a protective film 147. An amorphous hafnium oxide film containing 1 at% to 16 at% hydrogen is used for the gate insulating film 142. The thickness of the gate insulating film 142 of the thin-film transistor is typically 50 nm to 500 nm. Because the film is amorphous and contains a predetermined amount of hydrogen, the number of grain boundaries is very small, and a high dielectric constant can be achieved. Therefore, the thin-film transistor including the gate insulating film 142 according to this embodiment can significantly reduce leakage current. Liquid crystal displays and organic electroluminescent (OEL) displays are semiconductor devices including thin-film transistors. A high-dielectric film according to a second embodiment can be used as the gate insulating film of the thin-film transistor in a liquid crystal display or an OEL display.

[0168] It should be noted that the application of amorphous hafnium oxide films containing 1 at% to 16 at% hydrogen as gate insulating films in thin-film transistors is not limited to... Figure 14 Examples include the following: For instance, the semiconductor layer constituting the channel is not limited to a low-temperature polycrystalline silicon layer, but can also be composed of an amorphous silicon layer or an oxide semiconductor layer such as IGZO, and the substrate is not limited to a glass substrate. Similarly, in this case, the leakage current in the thin-film transistor including the aforementioned gate insulating film can be significantly reduced.

[0169] Example 13

[0170] The substrate on which the optical structure of the first embodiment is provided may have an optoelectronic structure. An optoelectronic structure is a structure that converts an electrical signal into an optical signal or vice versa. Figure 15 This is a schematic partial cross-sectional view illustrating an example of a back-illuminated imaging element. The imaging element is an optical element because it processes light, and it is a semiconductor element because it includes photodiodes and transistors. In the back-illuminated imaging element 150, photodiodes PD corresponding to each pixel are formed in a semiconductor substrate 151. The semiconductor substrate 151 serves as a substrate including a photoelectric structure that converts light signals into electrical signals. Each photodiode PD includes a pn junction formed by an n-type region 152 extending along the thickness direction of the semiconductor substrate 151 and a p-type region 153 contacting the n-type region 152 on both the front and back sides of the substrate. Each pixel's photodiode PD is separated by a p-type element isolation region 154. A p-type semiconductor well region 155, contacting the element isolation region 154, is formed on the front side of the semiconductor substrate 151, i.e. Figure 15The lower side of the image is provided with a pixel transistor corresponding to each pixel. The pixel transistor consists of a source region, a drain region, a gate insulating film, and a gate electrode 156. In addition, an interlayer insulating film 157 and multilayer wiring 158 are provided on the front side.

[0171] Meanwhile, on the back side of the semiconductor substrate 151 used as the light receiving side (i.e. Figure 15 An antireflection structure 160 with electrical insulation and antireflection functions is formed on the upper side of the semiconductor substrate 151. The antireflection structure 160 has a double-layer structure, and a silicon oxide film 161 and a hafnium oxide film 162 are sequentially stacked from the semiconductor substrate 151 side. A film with a refractive index of 1.506 as shown in Example 5 is preferably used for the silicon oxide film 161. An amorphous hafnium oxide film with a hydrogen content of 6.5 at% and a refractive index of 2.253 as shown in Example 5 is preferably used for the hafnium oxide film 162.

[0172] To suppress crosstalk of incident light between pixels, for example, a light-shielding film 163 made of aluminum is provided on the anti-reflection structure 160, and a planarization film 164 made of resin is provided thereon to provide a flat upper surface. On the planarization film 164, on-chip color filters 165 and on-chip microlenses 166, for example, in a Bayer arrangement, are formed. The light-shielding film 163 is formed of a metal such as aluminum or tungsten and can also serve as an electrode imparting a fixed potential. The anti-reflection structure 160 also acts as an insulating film, which insulates the light-shielding film 163 from the semiconductor substrate 151, which serves as a semiconductor layer.

[0173] In this embodiment, by providing an amorphous hafnium oxide film containing 1 at% to 16 at% hydrogen on the photodiode, high antireflection performance and low light absorption performance can be achieved, thereby enabling a high-sensitivity imaging element.

[0174] It should be noted that imaging elements using amorphous hafnium oxide films containing 1 at% to 16 at% hydrogen are not limited to... Figure 15 Examples of this can be found, and the hafnium oxide film can also preferably be used as an antireflective structure, for example, in a front-illuminated imaging element rather than in a back-illuminated imaging element. In a front-illuminated imaging element, the amorphous hafnium oxide film can be used simultaneously as an antireflective film and a gate insulating film. For example, the amorphous hafnium oxide film can be used as the gate insulating film of the transistor in the pixel circuit, and the amorphous hafnium oxide film can extend to the top of the photodiode and serve as an antireflective film.

[0175] Furthermore, by using imaging elements including the aforementioned anti-reflective structure, various cameras (e.g., interchangeable lens cameras and integrated lens cameras), as well as camera modules for smartphones and vehicles, can be manufactured. In addition to the lens and imaging element, the camera module may also include a holding portion, such as a frame holding multiple optical components, including the lens and imaging element. Of course, the lens of the camera module may be coated with a hafnium oxide film. Furthermore, the optical element including a substrate with a photoelectric structure can be a liquid crystal display or an OEL display. Besides optical elements including a substrate with a photoelectric structure, electronic devices such as cameras or smartphones may also include a controller for electrically controlling the photoelectric structure. Furthermore, when the optical element is an imaging element, the electronic device may include a processor for processing signals output from the imaging element. Furthermore, when the optical element is a display element, the electronic device may include a processor for processing signals input to the display element. The electronic devices to which this embodiment applies can be information devices such as smartphones or personal computers. Alternatively, the electronic device can be office equipment such as printers or copiers, medical devices such as X-ray imaging devices or endoscopes, industrial equipment such as robots or semiconductor manufacturing equipment, or transportation equipment such as vehicles, airplanes, or ships.

[0176] Modified embodiments of the first and second implementation schemes

[0177] It should be noted that the present invention is not limited to the above-described embodiments and examples, and can be modified in many ways within the technical concept of the present invention.

[0178] The high-refractive-index film according to the first embodiment can be widely used to coat optical elements, such as lenses, mirrors, prisms, imaging elements (image sensors), and display elements (display devices) such as displays. Furthermore, the high-refractive-index film can be used in optical devices, such as exposure apparatuses, various cameras, and interchangeable lenses that include optical elements. In addition to multiple optical components comprising optical elements coated with hafnium oxide films, these optical devices may also include holding portions, such as lens barrels, for holding multiple optical components. By stacking the high-refractive-index film according to the first embodiment with a low-refractive-index film having a lower refractive index, a high-performance anti-reflection structure or a reflective structure can be formed. For example, in an exposure apparatus including an ultraviolet light source, by providing an anti-reflection structure according to the first embodiment to a lens and / or a reflective structure according to the first embodiment to a mirror, the exposure performance of the exposure apparatus using ultraviolet light can be improved.

[0179] The high-dielectric film according to the second embodiment can be widely used as the gate insulating film of various transistors, and can be implemented in various semiconductor elements (semiconductor devices) such as memory, processors, and logic integrated circuits, as well as various electronic devices such as smartphones and personal computers. Electronic devices to which this embodiment can be applied can be information devices such as smartphones or personal computers, or communication devices such as modems or routers. Alternatively, electronic devices can be office equipment such as printers or copiers, medical equipment such as X-ray imaging devices or endoscopes, industrial equipment such as robots or semiconductor manufacturing equipment, or transportation equipment such as vehicles, airplanes, or ships.

[0180] In the following description, embodiments using tantalum oxide as a transition metal oxide are presented as the third and fourth embodiments. Tantalum oxide possesses a high refractive index and a high dielectric constant, thus its application in optical and semiconductor components is considered. In various optical devices such as exposure apparatuses, optical films are coated onto optical elements to improve optical properties such as anti-reflection and reflection characteristics. In capacitor and semiconductor components, insulating films are used to insulate capacitor electrodes or gate electrodes from other components.

[0181] In the field of optical components, there is a desire to achieve optical films with a good balance between high refractive index and low light absorption, as well as high performance.

[0182] In the field of electronic components, there is a desire to achieve insulating films with a good balance of high dielectric constant and low leakage current, as well as high performance.

[0183] Therefore, this embodiment aims to provide a technology that facilitates the achievement of high performance in tantalum oxide-containing films. One aspect of the third and fourth embodiments is a film comprising amorphous tantalum oxide as the main component and having a hydrogen content of 1.0 at% or higher.

[0184] According to this embodiment, a technology that facilitates high performance can be provided by achieving a good balance between high refractive index and low absorption rate, as well as a good balance between high dielectric constant and low leakage current.

[0185] The invention will be described with reference to the accompanying drawings, including a tantalum oxide film with a hydrogen content within a predetermined range, and an optical device comprising the film. It should be noted that although the terms "film" and "layer" are used in this specification, these terms are used according to convention in the art without a strict distinction between them, and there is no intention in this specification to strictly distinguish between the two terms.

[0186] Third Implementation Plan

[0187] Figure 16This is a schematic cross-sectional view of an optical element according to this embodiment. The optical element 100 includes a substrate 101 and an optical structure 102 formed on the substrate 101. The optical structure 102 may be referred to as a multilayer film, wherein a high-refractive-index layer 102a formed of a high-refractive-index material and a low-refractive-index layer 102b formed of a low-refractive-index material are alternately stacked. Here, alternating stacking of first-type and second-type layers means that at least one second-type layer is located between two first-type layers, and at least one first-type layer is located between two second-type layers. Thus, a construction including a total of at least four first-type and second-type layers is shown.

[0188] The substrate 101 can be made of materials such as calcium fluoride crystal, quartz glass, optical glass such as borosilicate crown glass BK7, resin, or metal. In addition, the substrate 101 can be of various shapes, such as planar shapes and curved shapes, depending on the application and type of optical elements such as lenses, mirrors, filters, or prisms.

[0189] The material used as the main component of the high refractive index layer 102a is tantalum oxide (Ta2O5), and the hydrogen content of the tantalum oxide (Ta2O5) in the present embodiment is within a predetermined range, as described below. It should be noted that in the following description, in some cases, a film containing tantalum oxide (Ta2O5) as the main component is also described as a tantalum oxide film. In the present embodiment, the tantalum oxide film is an optical film and constitutes the optical structure 102. Tantalum oxide is a metal oxide with a metal component of tantalum. In a film with a metal oxide as the main component, the content of the metal component (tantalum) is represented by J (at%), and the oxygen content is represented by K (at%). Here, a film containing tantalum oxide as the main component means that, for example, in the case where it is assumed that the film contains two other elements in addition to tantalum oxide, the content (at%) of each element satisfies the following relationship. That is, the sum of the tantalum content J (at%) and the oxygen content K (at%) is greater than the respective contents L (at%) and M (at%) of each element other than tantalum and oxygen (J + K > L, and J + K > M). Since the tantalum oxide film of the present embodiment necessarily contains a predetermined amount of hydrogen, J + K is less than  100 at%. According to the stoichiometric composition Ta2O5, typically 2×J < K < 3×J holds. The tantalum content J is, for example, in the range of 15 at% to 35 at%, and typically in the range of 20 at% to 30 at%, and the oxygen content K is, for example, in the range of 50 at% to 75 at%, and typically in the range of 60 at% to 70 at%. The sum of the tantalum content J (at%) and the oxygen content K (at%) of the tantalum oxide film is preferably greater than the sum of the contents L (at%) and M (at%) of all elements other than tantalum and oxygen contained in the tantalum oxide film (J + K > L + M). In this case, J + K is higher than 50 at%. Although the case of providing two elements other than tantalum and oxygen is described as an example here, the number of elements other than tantalum and oxygen is not limited to two and may also be one. In the former case, the two elements in the tantalum oxide film of the present embodiment are hydrogen and argon, and in the latter case, the one element is hydrogen.

[0190] In the membrane of this embodiment, which contains tantalum oxide as the main component, hydrogen is a necessary element in addition to tantalum and oxygen, and argon is an optional element. The argon content can be, for example, 0.5 at% or more, 5.0 at% or less, 3.0 at% or less, and 2.0 at% or less. For example, the argon content range can be from 0.9 at% to 1.6 at%. As a result of analysis of the tantalum oxide membrane of this embodiment, the content of elements other than tantalum, oxygen, hydrogen, and argon is below the detection limit. Therefore, in the membrane of this embodiment, which uses tantalum oxide as the main component, elements other than these four are typically substantially absent. In addition to these four elements, the tantalum oxide membrane may also contain elements such as boron (B), carbon (C), nitrogen (N), fluorine (F), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), and chlorine (Cl) from group A elements. In addition to these four elements, the tantalum oxide membrane may also contain elements such as iron (Fe), nickel (Ni), chromium (Cr), niobium (Nb), and tungsten (W) from transition elements. In the membrane of this embodiment, if the content of each element other than the four mentioned above is less than 0.5 atomic%, particularly less than 0.1 atomic%, then light absorption caused by the elements other than the four mentioned above can be sufficiently suppressed. The content of each element other than the four mentioned above being below the detection limit means that the content of each element other than the four mentioned above can be 0 at%.

[0191] Examples of materials used for the low refractive index layer 102b include materials containing silicon oxide or aluminum oxide as the main component, but the construction is not limited to these. For example, MgF2, CaF2, LaF3, CeF3, YF3, etc. can be used.

[0192] like Figure 16 As shown, the optical structure 102 has the following configuration: a high refractive index layer 102a and a low refractive index layer 102b are alternately stacked from the substrate 101 side, with the outermost layer being the low refractive index layer 102b. It should be noted that this configuration can be varied depending on the application of the optical element. For example, a configuration can also be used where the low refractive index layer 102b and the high refractive index layer 102a are alternately stacked from the substrate 101 side, with the outermost layer being the low refractive index layer 102b. Furthermore, a protective layer can be provided on the outermost low refractive index layer 102b to make it the outermost layer, and a medium refractive index layer formed of a material with a medium refractive index can be provided between the high refractive index layer 102a and the low refractive index layer 102b. Alternatively, a substrate layer, such as an adhesive layer, can be provided between the substrate 101 and the optical structure 102. It should be noted that the optical structure 102 of this embodiment does not necessarily have an alternating stacked structure of low refractive index layer 102b and high refractive index layer 102a as shown in the figure. In addition, the optical structure 102 does not necessarily have a multilayer structure including high refractive index layer 102a and low refractive index layer 102b, and may have a single-layer structure including only one high refractive index layer 102a.

[0193] A method for manufacturing an optical element according to this embodiment will be described, the optical element comprising a tantalum oxide film with a hydrogen content within a predetermined range as a high refractive index layer. It should be noted that known film-forming methods can be used to form a low refractive index layer 102b, therefore its description will be omitted.

[0194] Figure 17 This is a schematic diagram of a sputtering film deposition apparatus 200 for manufacturing optical components. The sputtering film deposition apparatus 200 includes a vacuum chamber 201 serving as a hermetically sealed container and an exhaust system 202 for venting air from the vacuum chamber 201. Furthermore, the sputtering film deposition apparatus 200 includes an argon inlet 204, an oxygen inlet 205, and a hydrogen inlet 206, allowing the gases required for film deposition to be introduced into the vacuum chamber 201. Additionally, a sputtering target 210, a backplate 211, a magnet mechanism 207, and a substrate holding mechanism 208 are provided to the vacuum chamber 201. By holding the substrate 101 of the optical component in the substrate holding mechanism 208 and supplying power to it from the power source 203, film deposition can be performed using a reactive sputtering method.

[0195] To form a hydrogen-containing tantalum oxide film for use as a high refractive index layer, film deposition is performed by reactive sputtering according to the following steps. For example, a substrate 101 and a 9-inch tantalum metal are placed in a vacuum chamber 201. The substrate is made of quartz glass machined into a predetermined optical element shape, and the tantalum metal has a purity of 99.9 wt% or higher and serves as a sputtering target 210. The distance between the substrate 101 and the sputtering target 210 is set to, for example, 200 mm. Furthermore, air in the vacuum chamber 201 is exhausted by an exhaust system 202 to achieve a density of approximately 5 × 10⁻⁶ m / s. -5 A vacuum of Pa is established. Then, plasma discharge is performed simultaneously by introducing argon gas through argon inlet 204, oxygen gas through oxygen inlet 205, and hydrogen gas through hydrogen inlet 206. That is, plasma discharge is achieved by applying 10 W / cm² to the sputtering target 210 from the power supply 203. 2 The power is used to generate plasma discharge, and a hydrogen-containing tantalum oxide film with a thickness of approximately 100 nm is formed on a substrate 101, for example, with a diameter of 30 mm and a thickness of 1 mm. The hydrogen content in the film is adjusted by changing the hydrogen flow rate. It should be noted that the thickness of each layer is not necessarily limited to approximately 100 nm, and can be appropriately set according to the wavelength of the light used in the optical element and the number of layers constituting the optical structure. The physical thickness of the tantalum oxide film in the optical element is, for example, 8 nm to 1000 nm, preferably 8 nm to 100 nm. A tantalum oxide layer with a thickness of 100 nm can be stacked without any other layers to form a tantalum oxide film with a thickness of 1000 nm. Specific embodiments and comparative examples will be described below.

[0196] Examples 1 to 5 and Comparative Examples 1 and 2

[0197] The high refractive index layer for the optical structure will be described with reference to Examples 1 to 5 and Comparative Examples 1 and 2. All high refractive index layers according to Examples 1 to 5 and Comparative Example 2 are formed when oxygen is introduced through oxygen inlet 205 at a flow rate of 200 sccm. In all examples and comparative examples, the film is formed by introducing argon gas from argon inlet 204 at a flow rate of 200 sccm. In Example 1, plasma discharge is performed simultaneously with the introduction of hydrogen gas through hydrogen inlet 206 at a flow rate of 20 sccm. In other examples and comparative examples, as described below, the amount of hydrogen contained in the film is adjusted by changing the hydrogen flow rate from Example 1. In all examples and comparative examples, film formation is performed such that the film thickness is approximately 100 nm. It should be noted that the above film formation conditions are merely examples and can be appropriately modified according to the structure of the film formation apparatus, etc.

[0198] For the single tantalum oxide films of each embodiment and each comparative example, the hydrogen content, light absorption rate, refractive index, and crystallinity were evaluated.

[0199] The hydrogen content of the tantalum oxide film was evaluated, for example, by irradiating the film with a high-energy ion beam at the MeV level and performing hydrogen forward scattering spectroscopy (HFS). For materials other than hydrogen in the film, the evaluation was performed by irradiating the film with a high-energy ion beam at the MeV level and performing Rutherford backscattering spectroscopy (RBS). The contents (at%) of hydrogen, tantalum, oxygen, and argon in the tantalum oxide film were obtained using these results. It should be noted that the accuracy of hydrogen content determination is ±0.1% in the trace range below 1% and ±0.4% in the range above 3%.

[0200] In addition, light absorptivity and refractive index were evaluated by measuring transmittance and reflectance at a beam incident angle of 5° in the wavelength range of 200 nm to 500 nm using an ultraviolet-visible-near-infrared spectrometer.

[0201] Calculate the light absorption rate using the following formula.

[0202] A(%) = 100 - T(%) - R(%) (Equation 1)

[0203] In the formula, A(%) represents light absorption rate, T(%) represents transmittance, and R(%) represents reflectance.

[0204] Using Film Wizard, an optical thin film analysis / design software available from Scientific Computing International. TM The refractive index is calculated by analyzing the measured reflectance.

[0205] Crystallinity was evaluated using X-ray diffraction analysis. In the following description, amorphous state refers to the condition where, when X-rays are irradiated onto the film being measured at a small incident angle of approximately 0.5° and the diffraction pattern is observed, no obvious diffraction peaks are detected; in other words, a halo pattern is observed. Therefore, the amorphous state described herein does not necessarily exclude the presence of microcrystalline materials.

[0206] Figure 27 The X-ray diffraction pattern (incident angle: 0.4°) of the high refractive index layer (i.e., a tantalum oxide film with a hydrogen content within a predetermined range) of this embodiment is shown as an example. As shown, since only a halo pattern was observed and no obvious crystallization peaks were observed, it can be determined that the high refractive index film of this embodiment is an amorphous film. All tantalum oxide films with a hydrogen content of 1.0 at% or more but less than 10.0 at% (such as the tantalum oxide film described as an example) are amorphous. It should be noted that for crystalline tantalum oxide films such as single crystals or polycrystalline tantalum oxide, no advantage was found when setting the hydrogen content to 1.0 at% compared to setting it to a value on the order of ppm. Furthermore, under film formation conditions with a hydrogen content of 10.0 at% or more, films that are easy to analyze were not obtained.

[0207] Tables 7 and 8 show the evaluation results of Examples 1 to 5 and Comparative Examples 1 and 2. Table 7 shows the hydrogen content, refractive index for light at a wavelength of 313 nm, light absorptivity for light at a wavelength of 313 nm, average light absorptivity in the wavelength range of 290 nm to 310 nm, and average light absorptivity in the wavelength range of 350 nm to 500 nm for each film. Table 8 shows the content (at%) of each element contained in each film. It should be noted that although the sum of the contents of each example in Table 8 is not 100 at%, this is because the second decimal place of each content is rounded. If the second decimal place, the third decimal place, etc., are taken into account, the sum is 100 at%.

[0208] Table 7

[0209]

[0210] Table 8

[0211]

[0212] Regarding the crystallinity of the tantalum oxide film in Example 1, the tantalum oxide film is amorphous, and the hydrogen content of the tantalum oxide film is 1.0 at%. Furthermore, for a wavelength of 313 nm, the light absorptivity and refractive index of the tantalum oxide film in Example 1 are 0.40% and 2.48, respectively. The average light absorptivity in the wavelength range of 290 nm to 310 nm is 2.50%, and the average light absorptivity in the wavelength range of 350 nm to 500 nm is 0.00%.

[0213] Regarding the crystallinity of the tantalum oxide film in Example 2, the tantalum oxide film is amorphous, and the hydrogen content of the tantalum oxide film is 3.0 at%. Furthermore, for a wavelength of 313 nm, the light absorptivity and refractive index of the tantalum oxide film in Example 2 are 0.30% and 2.46, respectively. The average light absorptivity in the wavelength range of 290 nm to 310 nm is 3.09%, and the average light absorptivity in the wavelength range of 350 nm to 500 nm is 0.03%.

[0214] Regarding the crystallinity of the tantalum oxide film in Example 3, the tantalum oxide film is amorphous, and the hydrogen content of the tantalum oxide film is 6.3 at%. Furthermore, for a wavelength of 313 nm, the light absorptivity and refractive index of the tantalum oxide film in Example 3 are 0.14% and 2.44, respectively. The average light absorptivity in the wavelength range of 290 nm to 310 nm is 2.23%, and the average light absorptivity in the wavelength range of 350 nm to 500 nm is 0.00%.

[0215] Regarding the crystallinity of the tantalum oxide film in Example 4, the tantalum oxide film is amorphous, and the hydrogen content of the tantalum oxide film is 9.0 at%. Furthermore, for a wavelength of 313 nm, the light absorptivity and refractive index of the tantalum oxide film in Example 4 are 0.07% and 2.43, respectively. The average light absorptivity in the wavelength range of 290 nm to 310 nm is 1.24%, and the average light absorptivity in the wavelength range of 350 nm to 500 nm is 0.01%.

[0216] Regarding the crystallinity of the tantalum oxide film in Example 5, the tantalum oxide film is amorphous, and the hydrogen content of the tantalum oxide film is 9.6 at%. Furthermore, for a wavelength of 313 nm, the light absorptivity and refractive index of the tantalum oxide film in Example 5 are 0.03% and 2.43, respectively. The average light absorptivity in the wavelength range of 290 nm to 310 nm is 1.19%, and the average light absorptivity in the wavelength range of 350 nm to 500 nm is 0.08%.

[0217] Regarding the crystallinity of the tantalum oxide film in Comparative Example 1, the tantalum oxide film is amorphous, and its hydrogen content is 0.2 at%. Furthermore, for a wavelength of 313 nm, the light absorptivity and refractive index of the tantalum oxide film in Comparative Example 1 are 0.42% and 2.46, respectively. The average light absorptivity in the wavelength range of 290 nm to 310 nm is 3.72%, and the average light absorptivity in the wavelength range of 350 nm to 500 nm is 0.01%.

[0218] Regarding the crystallinity of the tantalum oxide film of Comparative Example 2, the tantalum oxide film is amorphous, and the hydrogen content of the tantalum oxide film is 0.6 at%. Further, for a wavelength of 313 nm, the light absorption rate and the refractive index of the tantalum oxide film of Comparative Example 2 are 0.42% and 2.46, respectively. The average light absorption rate in the wavelength range of 290 nm to 310 nm is 3.66%, and the average light absorption rate in the wavelength range of 350 nm to 500 nm is 0.01%.

[0219] It should be noted that for the tantalum oxide film of the present embodiment, it is not necessary to actively add any impurities other than hydrogen to the tantalum oxide film, and the impurity content X of the tantalum oxide film is preferably lower than the hydrogen content L (X < L). Here, the impurity is an element other than oxygen, tantalum, and hydrogen, and the impurity content X is the sum of the impurity contents. The impurity content X of the tantalum oxide film described in the above embodiment is less than 5.0 at%, 3.0 at% or less, or 2.0 at% or less. In the case of a tantalum oxide film to which a large amount of impurities (X > L) are added, not only does the addition of impurities reduce the refractive index, but light absorption is not necessarily sufficiently suppressed. The tantalum oxide film of the present embodiment may contain elements other than tantalum, oxygen, and hydrogen. For example, the tantalum oxide film described in the above embodiment may contain argon. The argon is derived from the argon gas introduced through the argon gas inlet 204 during film formation. The argon content M in the tantalum oxide film is preferably less than the hydrogen content L (M < L). For example, the argon content M in the tantalum oxide film is in the range of 0.5 at% to 5 at%. <00,00717>Even when the film contains argon, the present embodiment can achieve a high refractive index and a low light absorption rate. It should be noted that for the tantalum oxide film of the present embodiment, it is not necessary to actively add silicon to the tantalum oxide film, and the silicon content O of the tantalum oxide film is preferably lower than the hydrogen content L (O < L). The silicon content O of the tantalum oxide film described in the above embodiment is less than 1 at%, 0.1 at% or less, or below the detection limit. In the case of a tantalum oxide film to which silicon is added, the addition of silicon not only causes fluctuations in the refractive index, but light absorption is not necessarily sufficiently suppressed. In the tantalum oxide film of the present embodiment, it is not necessary to actively add carbon to the tantalum oxide film, and the carbon content P in the tantalum oxide film is preferably less than the hydrogen content L (P < L). The carbon content P of the tantalum oxide film described in the above embodiment is less than 1 at%, 0.1 at% or less, or below the detection limit. In the tantalum oxide film of the present embodiment, it is not necessary to actively add nitrogen to the tantalum oxide film, and the nitrogen content Q of the tantalum oxide film is preferably less than the hydrogen content L (Q < L). The nitrogen content Q of the tantalum oxide film described in the above embodiment is less than 1 at%, 0.1 at% or less, or less than the detection limit.

[0221] The inventors employed a model in which hydrogen undergoes an addition reaction with tantalum oxide in hydrogen-containing tantalum oxide. When assuming the stoichiometric composition of tantalum oxide with a hydrogen content of 0 at% is Ta₂O₅, hydrogen-containing tantalum oxide can be modeled as Ta₂O₅H. x Hydrogen added to Ta₂O₅ bonds with tantalum or oxygen and can terminate dangling bonds in tantalum or oxygen. Hydrogen can also enter the bonds between tantalum and oxygen or between lattice spaces. Using this model, the hydrogen concentration calculated by simulation is approximately 4 × 10⁻⁶ for a hydrogen content of 1 at%. 20 atoms / cm 3 With a hydrogen content of 3 at%, it is approximately 1 × 10⁻⁶. 21 atoms / cm 3 With a hydrogen content of 6 at%, it is approximately 2 × 10⁻⁶. 21 atoms / cm 3 With a hydrogen content of 9 at%, it is approximately 4 × 10⁻⁶. 21 atoms / cm 3 When the hydrogen content is above 10 at%, it is approximately 5 × 10. 21 atoms / cm 3 That's all. The hydrogen concentration of the tantalum oxide film in this embodiment can be 4 × 10⁻⁶. 20 atoms / cm 3 Above and less than 5×10 21 atoms / cm 3 Preferred in terms of atoms / cm 3 This indicated hydrogen concentration range satisfies an appropriate hydrogen content (at%). Furthermore, the hydrogen concentration of the tantalum oxide film in this embodiment can be 1 × 10⁻⁶. 21 atoms / cm 3 Above, 2×10 21 atoms / cm 3 The above, and is 4×10 22 atoms / cm 3 Below. However, depending on the amount of impurities such as argon and the packing density of the tantalum oxide film, within 4 × 10⁻⁶... 20 atoms / cm 3 Within the hydrogen concentration range, it can meet the requirements of 1 at% to 10 at% or 3 at% to 9 at% hydrogen content, and is greater than 5 × 10 21 atoms / cm 3 Within the hydrogen concentration range, it can meet the requirements of 1at% to 10at% or 3at% to 9at% hydrogen content.

[0222] Because a high-output light source is used in the exposure apparatus, when the optical film formed in the optical element of the apparatus is illuminated by light from the light source and light absorption occurs in the optical film, the light absorption can cause the temperature of the optical element and the surrounding atmosphere to rise. When thermal expansion occurs in the optical element or the surrounding mechanical components due to the temperature rise, the thermal expansion can lead to a decrease or instability in the focusing performance of the exposure apparatus. Furthermore, although multilayer films are typically used to improve the optical properties of the optical film, the effective intensity of the exposed light can decrease in some cases because the loss of light due to light absorption becomes more significant when the number of layers is large.

[0223] Furthermore, although light sources with emission wavelengths in the visible light region (such as the g-line (436 nm and h-line (405 nm)), the ultraviolet region (such as the i-line (365 nm and j-line (313 nm)), and the DUV range (290 nm to 310 nm) can be used, the highest achievable resolution depends on the wavelength of the exposed light. The exposed light emitted from the light source of the exposure apparatus may include, for example, light with at least one wavelength in the range of 280 nm to 330 nm, such as the j-line, and light with at least one wavelength in the range of 330 nm to 380 nm, such as the i-line.

[0224] Therefore, to consistently achieve high resolution, it is desirable to use short-wavelength light, such as the j-line (313 nm), as the exposure light. Consequently, the films and layers disposed in the optical path are preferably made of materials that exhibit low light absorption for short-wavelength light, such as the j-line (313 nm). In addition to improving resolution, exposure time can be shortened and production throughput increased by using light with a wide wavelength range to increase illuminance on the photoresist.

[0225] Tantalum oxide is characterized by its high refractive index in the visible wavelength range, making it a widely used material in optical devices utilizing this range. However, due to relatively large light absorption in tantalum oxide in the wavelength range close to the j-line, problems of heat generation or light loss can occur when tantalum oxide is placed in the optical path of ultraviolet light, such as the j-line.

[0226] For example, as a condition for suppressing the thermal impact on the exposure performance of the exposure apparatus or suppressing light loss, it can be mentioned that the light absorption rate of the tantalum oxide film at the j-line wavelength (313 nm) is 0.40% or less, more preferably 0.30% or less. Furthermore, for the wavelength range of 350 nm to 500 nm, including the g-line, h-line, and i-line, the average light absorption rate is preferably 0.10% or less, more preferably 0.08% or less, and even more preferably 0.05% or less. In the following description, the condition satisfying these conditions is sometimes referred to as "low absorption".

[0227] Comparing Examples 1 to 5, where the hydrogen content in the membrane is between 1.0 at% and 10.0 at%, with Comparative Examples 1 and 2, where the hydrogen content is less than 1.0 at%, it can be said that they all exhibit low absorption in the wavelength range of 350 nm to 500 nm. In contrast, in Comparative Examples 1 and 2, the absorption for light at a wavelength of 313 nm exceeds 0.40%, while in Examples 1-5, the light absorption is confirmed to be below 0.40%, which is considered low absorption.

[0228] Figure 18 A dashed graph showing the relationship between hydrogen content and light absorbance (wavelength: 313 nm) and a solid graph showing the relationship between hydrogen content and light absorbance (average value in the wavelength range of 350 nm to 500 nm) are shown. Furthermore, Figure 19 The absorption spectra of Examples 4, 5 and Comparative Example 1 are shown, and it can be seen that the light absorption rate in the wavelength range below 325 nm is significantly reduced in the Examples compared with the Comparative Example.

[0229] like Figure 18 As shown, in Examples 1 to 5, the light absorption at a wavelength of 313 nm decreased as the hydrogen content increased from 1.0 at%. Furthermore, when the hydrogen content exceeded 9.0 at%, the light absorption showed an increasing trend in the wavelength range of 350 nm to 500 nm. As described above, it can be seen that the change in light absorption varies in each wavelength range depending on the difference in hydrogen content in the film, rather than showing a simple trend of increase or decrease across the entire wavelength range.

[0230] Figure 24 The relationship between the hydrogen content of tantalum oxide and its refractive index at a wavelength of 365 nm is shown in Table 7. The values ​​at a wavelength of 313 nm are shown below. Figure 24 The values ​​shown at a wavelength of 365 nm illustrate that the refractive index is similarly high even with extremely low hydrogen content, provided the hydrogen content is above 1.0 at% and below 10.0 at%. For example, the refractive index for light at a wavelength of 313 nm can be above 2.40 or above, or above 2.43.

[0231] As described above, the tantalum oxide film of this embodiment, which has a high refractive index and achieves low light absorption in the ultraviolet region including the j-line, preferably contains 1.0 at% or more and less than 10.0 at% hydrogen. Particularly preferred is an amorphous tantalum oxide film containing 3.0 at% or more hydrogen, as it can achieve a high refractive index of 2.40 or more and low ultraviolet light absorption of 0.3% or less. To achieve low light absorption in the ultraviolet region including the j-line, the hydrogen content of the tantalum oxide film is preferably 3.0 at% or more, more preferably 6.0 at% or more. Tantalum oxide films with a hydrogen content greater than 9.0 at% can also achieve low light absorption for light in the wavelength range of 350 nm to 500 nm. However, the tantalum oxide film of this embodiment with a hydrogen content of 9.0 at% or less achieves particularly low light absorption for light in the wavelength range of 350 nm to 500 nm.

[0232] The mechanism by which light absorption increases and decreases based on the hydrogen content of the tantalum oxide film can be considered as follows. To account for the differences in absorption factors across different wavelength ranges, the wavelength ranges are divided into a first wavelength range and a second wavelength range. The first wavelength range is the range greater than 320 nm, encompassing the ultraviolet and visible light regions. The second wavelength range is the region below 320 nm, close to the absorption end. It should be noted that the absorption end is the wavelength at which absorption begins due to the band gap size, and as a reference, this absorption end is set at the wavelength where 0.3% light absorption occurs.

[0233] First, the effect of adding hydrogen could be to reduce light absorption in the first wavelength range. This is because the lattice defect energy levels formed in the band gap cause light absorption in the first wavelength range. When hydrogen is added to the film, it is expected that the hydrogen fills the defects to exhibit a passivation effect, thus making the film a low-absorption film. Furthermore, it is also expected that the film will become a high-durability film with little change in optical properties. However, as can be seen from Comparative Examples 1 and 2, when the hydrogen content is as low as less than 1.0%, the band gap is hardly affected, so it is not expected that a film with low light absorption in the second wavelength range will be obtained.

[0234] Considering the case where the hydrogen content of the tantalum oxide film is greater than 1.0 at% and less than 10.0%, firstly, a passivation effect is exhibited in the first wavelength range, and light absorption is suppressed to a low level. Furthermore, due to the suitable hydrogen content, light absorption in the second wavelength range is also suppressed to a low level.

[0235] It is believed that light absorption in the second wavelength range depends on the band gap specific to tantalum oxide. Dielectric materials such as tantalum oxide have a material-specific band gap, and the absorption end is determined by the size of the band gap. In the case of tantalum oxide, unique light absorption begins at wavelengths less than 320 nm. When the hydrogen content is 1.0 at% or more but less than 10.0 at% (preferably 3.0 at% or more but less than 9.0 at%), the amount of hydrogen required to fill the aforementioned defects is exceeded, resulting in excess hydrogen in the film. The state of the excess hydrogen in the film is unclear, but it is speculated that the excess hydrogen is trapped between bonds or forms new bonds as OH groups. Therefore, the material-specific band structure itself is also affected, leading to a widening of the band gap and a shift of the light absorption end towards the lower wavelength side. This is presumably the reason for the reduced light absorption in the second wavelength range.

[0236] It should be noted that when the hydrogen content of the tantalum oxide film exceeds 9 at%, the excess hydrogen is relatively large, and it is therefore believed that some of the hydrogen reduces oxygen, resulting in oxygen deficiency and increased light absorption in the first wavelength range. However, since the effect of reducing light absorption in the second wavelength range (e.g., the J line) is significant, the film is industrially useful in the range of less than 10.0 at%.

[0237] Furthermore, impurities can also be considered other factors affecting light absorption. Argon mixed into the film during the film formation process can be considered an impurity, but in all the above embodiments and comparative examples, the argon content in the film is less than 2 at%. It can be seen that in this embodiment, even when the film contains argon as an impurity, a film with high refractive index and low light absorption can be achieved. In addition, since the tantalum oxide of this embodiment does not contain impurities other than hydrogen and argon, light absorption from elements other than hydrogen and argon will not occur.

[0238] As described above, in this embodiment, a tantalum oxide film with a hydrogen content within a predetermined range is used. The tantalum oxide film of this embodiment, with a hydrogen content of 1.0 at% or more and less than 10.0 at%, is suitable for high-performance optical films, achieving low light absorption in the ultraviolet region (e.g., including the J-line) while possessing a high refractive index. The tantalum oxide film of this embodiment is more suitable to contain hydrogen of 3.0 at% or more and less than 9.0 at%

[0239] Examples 6 and 7 and Comparative Example 3

[0240] Next, specific examples of optical structures used as antireflection structures by using tantalum oxide films will be described with reference to Examples 6 and 7 and Comparative Example 3. Figure 20 It provides a cross-sectional view of a transmission-type optical element that serves as an anti-reflection optical structure.

[0241] The optical element 500 includes a quartz substrate 501 (which serves as a matrix) and an optical structure 502, wherein a total of six alternating layers are stacked, consisting of a high-refractive-index layer 502a formed of a high-refractive-index material and a low-refractive-index layer 502b formed of a low-refractive-index material.

[0242] The high-refractive-index layer 502a is formed of hydrogen-containing tantalum oxide. The low-refractive-index layers 502b, serving as the second and fourth layers, are formed of silicon oxide, and the sixth (outermost) low-refractive-index layer 502b is formed of magnesium fluoride. Here, considering its application in an exposure apparatus, the construction of the optical structure is determined by optimizing the physical film thickness of each layer of the optical element 500. That is, a design is adopted that maximizes the antireflective properties within a wavelength range of 310 nm to 450 nm, including the g-line, h-line, i-line, and j-line, which are characteristic bright lines of the light source used for exposure. It should be noted that, needless to say, the design for optimizing antireflective properties can be varied depending on the wavelength range of the light source used.

[0243] Example 6 is an optical element formed by alternately stacking a high refractive index layer and a low refractive index layer of tantalum oxide with a hydrogen content of 9.0 at% as described in Example 4 on a quartz substrate 501.

[0244] Example 7 is an optical element formed by alternately stacking a high refractive index layer and a low refractive index layer of tantalum oxide with a hydrogen content of 9.6 at% as described in Example 5 on a quartz substrate 501.

[0245] Comparative Example 3 is an optical element formed by alternately stacking a high refractive index layer and a low refractive index layer of tantalum oxide with a hydrogen content of 0.2 at% as described in Comparative Example 1 on a quartz substrate 501.

[0246] Table 9 shows the specifications of each layer of the optical element in Example 6.

[0247] Table 9

[0248] Material Refractive index Physical film thickness (nm) Sixth floor Magnesium fluoride 1.47 70.5 Fifth floor Tantalum oxide 2.43 23.7 Fourth floor silicon dioxide 1.49 17.5 Third layer Tantalum oxide 2.43 27.6 Second floor silicon dioxide 1.49 30.8 First layer Tantalum oxide 2.43 8.8 matrix Quartz glass 1.48 -

[0249] Table 10 shows the specifications of each layer of the optical element in Example 7.

[0250] Table 10

[0251] Material Refractive index Physical film thickness (nm) Sixth floor Magnesium fluoride 1.47 70.5 Fifth floor Tantalum oxide 2.43 23.7 Fourth floor silicon dioxide 1.49 17.5 Third layer Tantalum oxide 2.43 27.6 Second floor silicon dioxide 1.49 30.8 First layer Tantalum oxide 2.43 8.8 matrix Quartz glass 1.48 -

[0252] Table 11 shows the specifications of each layer of the optical element in Comparative Example 3.

[0253] Table 11

[0254] Material Refractive index Physical film thickness (nm) Sixth floor Magnesium fluoride 1.47 70.5 Fifth floor Tantalum oxide 2.46 23.7 Fourth floor silicon dioxide 1.49 17.5 Third layer Tantalum oxide 2.46 27.6 Second floor silicon dioxide 1.49 30.8 First layer Tantalum oxide 2.46 8.8 matrix Quartz glass 1.48 -

[0255] Figure 21This is a coordinate graph showing the refractive index characteristics of the optical structures of Examples 6, 7 and Comparative Example 3. Figure 22 It is to extract and amplify. Figure 21 The coordinate graph of the smaller wavelength side. Figure 23 This is a coordinate graph showing the transmittance characteristics of the optical structures of Examples 6, 7 and Comparative Example 3.

[0256] from Figure 23 It can be seen that Examples 6 and 7 achieved higher transmittance than Comparative Example 3, especially in the ultraviolet region. This matches the results obtained in Examples 4 and 5 of tantalum oxide films with high refractive index and low light absorption in the ultraviolet region.

[0257] In addition, from Figure 21 It can be seen that, within the wavelength range of 300nm to 500nm, Examples 6 and 7 are comparable to Comparative Example 3. Furthermore, as... Figure 22 As shown, in the DUV region with wavelengths from 290 nm to 300 nm, the reflectance in Examples 6 and 7 is significantly reduced compared to Comparative Example 3. This indicates that hydrogen content within a predetermined range may improve the refractive index of light in the DUV region. Furthermore, the tantalum oxide films of Examples 6 and 7 have lower refractive indices than Comparative Example 3, therefore the reflectance theoretically obtainable in Examples 6 and 7, assuming no absorption, should be higher than that of Comparative Example 3, based solely on the relationship with refractive index. However, considering absorption... Figure 21 and Figure 22 The results show that the difference in reflectance between Examples 6 and 7 and Comparative Example 3 is smaller than the difference in theoretical reflectance, or the reflectance of Examples 6 and 7 is lower than that of Comparative Example 3. This is presumably because the reflectance properties are affected by absorption. In other words, regarding the optical structure designed with the theoretically optimal virtual complex refractive index (extinction coefficient = 0), compared to Comparative Example 3, the imaginary part (extinction coefficient) of the complex refractive index in Examples 6 and 7 is smaller and its difference from the virtual complex refractive index is smaller. Therefore, it is considered that the optical structures in Examples 6 and 7 deviate less from the optimal design compared to Comparative Example 3, thus achieving better optical properties.

[0258] Based on these results, when using a light source with high light intensity in the j-line or shorter wavelength range, the hydrogen content of the tantalum oxide film constituting the optical structure used as an antireflection structure is preferably set in the range of 1.0 at% or more and less than 10.0 at%, and particularly preferably in the range of 3.0 at% or more and less than 9.0 at%.

[0259] Furthermore, when using a light source that outputs light over a wide wavelength range (including j-lines and g-lines), the hydrogen content of the tantalum oxide film constituting the optical structure used as an antireflection structure is preferably set in the range of 1.0 at% or more and less than 10.0 at% . It is particularly preferred to set the hydrogen content in the range of 3.0 at% or more and less than 9.0 at% , because low light absorption can also be achieved for light in the wavelength range of 350 nm to 500 nm.

[0260] As described above, by using a tantalum oxide film with a hydrogen content within a predetermined range, it is possible to achieve a film with low light loss over a wide wavelength range while maintaining high antireflection properties.

[0261] Example 8 and Comparative Example 4

[0262] Next, specific embodiments of constructing an optical structure for use as a reflective structure by using a tantalum oxide film will be described with reference to Example 8 and Comparative Example 4. Figure 25 It is a cross-sectional view of a reflective optical element that provides an optical structure as a reflective structure.

[0263] The optical element 800 includes a quartz substrate 801 (which serves as a matrix) and an optical structure 802, wherein a total of 52 alternating layers of a high refractive index layer 802a formed of a high refractive index material and a low refractive index layer 802b formed of a low refractive index material are stacked.

[0264] The high-refractive-index layer 802a is formed of hydrogen-containing tantalum oxide. The low-refractive-index layer 802b is formed of silicon oxide. Considering the intended use of the optical element 800, the construction of the optical structure is determined by optimizing the physical film thickness of each layer of the optical element 800 to maximize the reflectivity in the wavelength range of 310 nm to 450 nm. It should be noted that, needless to say, the design for optimizing reflectivity can be varied depending on the wavelength range of the light source used.

[0265] Example 8 is an optical element formed by alternately stacking a high refractive index layer and a low refractive index layer of tantalum oxide containing 9.0 at% hydrogen as described in Example 4 on a quartz substrate 801.

[0266] Comparative Example 4 is an optical element formed by alternating layers of a high refractive index layer and a low refractive index layer of tantalum oxide containing 0.2 at% hydrogen as described in Comparative Example 1 on a quartz substrate 801.

[0267] Table 12 shows the specifications of each layer of the optical element in Example 8.

[0268] Table 12

[0269]

[0270] Table 13 shows the specifications of each layer of the optical element in Comparative Example 4.

[0271] Table 13

[0272]

[0273] Figure 26 The reflectance characteristics of the optical structures of Example 8 and Comparative Example 4 are shown. For example, when comparing the reflectance at 313 nm, Comparative Example 4, using tantalum oxide containing 0.2 at% hydrogen, has a reflectance of 98.5%. In contrast, Example 8, using tantalum oxide containing 9.0 at% hydrogen, has a reflectance of 99.9%, which is higher than Comparative Example 4. Since the refractive index changes very little with hydrogen content, this difference in reflectance can be attributed to differences in light absorption near 313 nm in the tantalum oxide film or layer. As described above, by using a tantalum oxide film with a hydrogen content within a predetermined range, ultraviolet light absorption can be suppressed, and high reflectance can be achieved.

[0274] When using a light source with high light intensity in the j-line or shorter wavelength range, the hydrogen content of the tantalum oxide film constituting the optical structure used as a reflective structure is preferably set in the range of 1.0 at% or more and less than 10.0 at%, and particularly preferably in the range of 3.0 at% or more and less than 9.0 at%.

[0275] Furthermore, when using a light source that outputs light across a wide wavelength range, including the j-line and g-line, the hydrogen content of the tantalum oxide film constituting the optical structure used as a reflective structure is preferably set in the range of 1.0 at% or more and less than 10.0 at% . It is particularly preferred to set the hydrogen content in the range of 3.0 at% or more and less than 9.0 at% , because low light absorption can also be achieved for light in the wavelength range of 350 nm to 500 nm.

[0276] Example 9 and Comparative Example 5

[0277] Specific examples will be described where at least one lens in a lens group included in an exposure apparatus is coated with an optical structure serving as an anti-reflection structure. Example 9 is a lens group in which two surfaces (i.e., a total of 30 surfaces) of 15 lenses included in the exposure apparatus are provided with an optical structure serving as an anti-reflection structure as described in Example 6. That is, in Example 9, an optical structure is formed on the surface of each lens by alternating layers of a tantalum oxide film containing 9.0 at% hydrogen used as a high-refractive-index layer and a low-refractive-index layer. Furthermore, Comparative Example 5 is a lens group in which two surfaces (i.e., a total of 30 surfaces) of 15 lenses included in the exposure apparatus are provided with an optical structure serving as an anti-reflection structure as described in Comparative Example 3. That is, in Comparative Example 5, an optical structure is formed on the surface of each lens by alternating layers of a tantalum oxide film containing 0.2 at% hydrogen used as a high-refractive-index layer and a low-refractive-index layer.

[0278] For Example 9 and Comparative Example 5, the suitability of the lens of the exposure apparatus, which includes a light source with a wavelength range up to the j-line, was evaluated by measuring the transmission loss using 313 nm ultraviolet light. Although the evaluation focuses on the j-line where absorption occurs in conventional tantalum oxide films, the suitability of the optical element can be evaluated based on the emission wavelength of the light source when using a light source with an emission wavelength range including infrared and visible light.

[0279] Table 14 shows the evaluation results.

[0280] Table 14

[0281]

[0282] In the lens group of Example 9, both low light absorption and low refractive index are achieved simultaneously on each surface, which can significantly reduce transmission loss. Therefore, the total transmission loss of the 30 surfaces of the 15 lenses can be suppressed to below 10%. In contrast, in Comparative Example 5, the light absorption is significantly higher than that of Example 9, and therefore the total transmission loss of the 30 surfaces of the 15 lenses is as high as 15% or more.

[0283] By using the lens group of Embodiment 9 as, for example, the illumination lens group or projection lens group of an exposure device, the lens group can be used without blocking ultraviolet light (which is typically blocked to prevent heat generation caused by light absorption), and the effect of increasing the total exposure intensity of the exposure device can be obtained. Therefore, the exposure time can be shortened, thereby improving the processing performance (production capacity) of the exposure device.

[0284] Example 10

[0285] Examples of applying tantalum oxide films (e.g., the films of one of Examples 1 to 5) with hydrogen content described as being within a predetermined range to optical components of an FPD exposure apparatus include, for example, mirrors used in the manufacture of flat panel displays (FPDs) such as liquid crystal displays. It should be noted that the amount within the predetermined range refers to the hydrogen content (at%) described in the above embodiments.

[0286] Figure 28 This is a schematic cross-sectional view of the exposure apparatus 1000 of this embodiment. The exposure apparatus 1000 is, for example, a projection exposure apparatus that exposes a processing target GS coated with photoresist PR onto a circuit pattern formed in a photomask RT using a step-scan method. For example, the exposure apparatus 1000 is preferably used in the manufacture of a liquid crystal display. The processing target GS is, for example, a glass substrate. The exposure apparatus 1000 also includes an observation mechanism for observing the photomask RT and the processing target GS. Figure 28 As shown, the exposure apparatus 1000 includes an illumination device 110, a projection optical system 620, a correction optical system 630, and an alignment mechanism 140.

[0287] The illumination device 110 illuminates the photomask RT on which the pattern to be transferred is formed, and includes a light source portion 112 and an illumination optics system 114. A mercury lamp is used for the light source portion 112. Therefore, the light source portion 112 outputs ultraviolet light with a wavelength range of 240 nm to 400 nm, including deep ultraviolet light with wavelengths below 300 nm. It should be noted that the number of light sources is not limited. The illumination optics system 114 is an optical system for illuminating the photomask RT.

[0288] The illumination optical system 114 includes lenses, mirrors, optical integrators, apertures, etc. For example, in the illumination optical system 114, a condenser lens, an optical integrator, an aperture stop, a condenser lens, a slit, and an imaging optical system are arranged sequentially. Examples of optical integrators include compound eye lenses and integrators composed of two overlapping cylindrical lens arrays or two overlapping biconvex lenses; however, the optical integrator can be replaced by an optical rod or a diffraction grating. In the transmissive optical elements, such as lenses, included in the illumination optical system 114, an anti-reflection structure illustrated in Embodiment 6 or 7 is formed. In the reflective optical elements, such as mirrors, included in the illumination optical system 114, a reflective structure illustrated in Embodiment 8 is formed.

[0289] The projection optics system 620 is an optical system that projects the pattern of a mask RT onto a processing target GS. Figure 28The projection optical system 620 of this embodiment shown is composed of a plane mirror 122, a concave mirror 124, and a convex mirror 126, but its construction is not limited to this. The reflective structure illustrated in Embodiment 8 is formed on the reflective surface of each mirror constituting the projection optical system 620. As described above, the reflective mirror including the reflective structure has minimal light absorption loss and high reflectivity for the wavelength range of the exposed light, thus achieving high illumination and enabling exposure processing to be performed in production volumes.

[0290] The correction optical system 630 is an optical system for correcting aberrations in the projection optical system 620. The correction optical system 630 includes one or more optical elements. In this embodiment, the correction optical system 630 is constructed of correction glass on which the anti-reflection structure illustrated in Embodiment 6 or 7 is formed, and is disposed between the mask RT and the projection optical system 620.

[0291] Alignment mechanism 140 has the function of aligning mask RT and processing target GS, and includes alignment light source 141, polarizer 145, semi-reflective mirror 142, reflector 143, polarizer 146, and detector 144. Alignment light source 141 is an illumination source in the visible light region (wavelength: 510nm to 760nm) for alignment. Alignment mechanism 140 is used for alignment between alignment mark AM1 on mask RT and alignment mark AM2 on processing target GS. The optical elements included in alignment mechanism 140 may be provided with anti-reflection structure illustrated in embodiment 6 or 7, or reflective structure illustrated in embodiment 8.

[0292] The light beam from the alignment light source 141 is linearly polarized by the polarizer 145 and illuminates the alignment mark AM1 via the semi-reflector 142 and the reflector 143. The reflected light reflected on the back of the mask RT is incident on the polarizer 146 via the reflector 143 and the semi-reflector 142, but the polarizer 146 is rotated to block the reflected light so that the reflected light does not incident on the detector 144.

[0293] Simultaneously, the light passing through the alignment mark AM1 is incident on the projection optical system 620. It should be noted that in this embodiment, the arrangement is set such that the light that is reflected five times on the plane mirror 122, the concave mirror 124, and the convex mirror 126 before reaching the alignment mark AM2 on the processing target GS has a 90° phase difference, and the light arrives at the alignment mark AM2 as circularly polarized light.

[0294] The light reflected from the alignment mark AM2 on the target GS passes through the projection optics system 620 again and returns to the mask RT. At this point, a phase difference is again assigned to the beam, so the light reaching the mask RT is linearly polarized. The polarization plane of the beam is perpendicular to the polarization plane of the illumination beam incident on the mask RT. The reflected light from the target GS illuminates the mask RT, passes through the semi-reflective mirror 142 and the polarizing plate 146, and is incident on the detector 144. Therefore, the detector 144 can detect both the mask RT and the target GS. Since the mask RT and the target GS are optically conjugate, the spotting caused by the linearly reflected light from the mask RT can be suppressed by removing the linearly polarized light reflected from the back of the mask RT. Therefore, the detector 144 can simultaneously detect the images of the mask RT and the target GS with high contrast, thus enabling high-precision alignment of the mask RT and the target GS.

[0295] In the exposure apparatus 1000 of this embodiment, a light beam emitted from an illumination device 110 (e.g., Kohler illumination) illuminates a mask RT. Light passing through the mask RT and reflecting the mask pattern is focused onto the processing target GS by a projection optics system 620. In this embodiment, an anti-reflection structure or a reflective structure using a tantalum oxide film with a hydrogen content within a predetermined range is provided on the optical surface of the optical elements disposed in the optical path, thereby suppressing the loss of light quantity in the exposed light and the alignment light. In particular, it is effective to use a mirror with a tantalum oxide film having a predetermined hydrogen content on it in the projection optics system 620.

[0296] In the exposure apparatus 1000 of this embodiment, light loss in both the exposure light and the alignment light is suppressed, and exposure can be performed economically with high resolution and high throughput. Furthermore, since heating of the optical elements caused by light absorption is suppressed, highly accurate alignment and exposure can be performed stably. It should be noted that the tantalum oxide film with a hydrogen content within a predetermined range does not necessarily need to be formed on all optical surfaces of the optical elements disposed on the optical path as in the above embodiment, and the tantalum oxide film can be provided only to any optical surface on which it is particularly desirable to suppress ultraviolet absorption.

[0297] Fourth Implementation Plan

[0298] The substrate on which the optical structure is provided can have a photoelectric structure. A photoelectric structure is a structure that converts an electrical signal into an optical signal or vice versa. An imaging element (image sensor) is an optical element because it processes light, and it is also a semiconductor element (semiconductor device) because it includes photodiodes and transistors. In a back-illuminated imaging element, photodiodes (PDs) corresponding to each pixel are formed in the semiconductor substrate. The semiconductor substrate acts as a substrate, which includes photoelectric structures for converting optical signals into electrical signals realized by the photodiodes. Furthermore, various cameras, such as interchangeable lens cameras and integrated lens cameras, as well as camera modules for smartphones and vehicles, can be manufactured using imaging elements including the aforementioned anti-reflective structures. The camera module may include a holding portion, such as a frame that holds multiple optical components (including lenses and imaging elements). Of course, the lens of the camera module may also be coated with a tantalum oxide film.

[0299] Furthermore, the optical element including the substrate containing the photoelectric structure can be a liquid crystal display or an OEL display. A reflective structure can be provided to improve the light utilization efficiency of the OEL display, and an optical structure containing tantalum oxide can be used for the reflective structure. In addition to optical elements including the substrate with the photoelectric structure, electronic devices such as cameras or smartphones can also include a controller for electrically controlling the photoelectric structure. Furthermore, if the optical element is an imaging element (camera device), the electronic device can include a processor for processing signals output from the imaging element. Furthermore, if the optical element is a display element (display device), the electronic device can include a processor for processing signals input to the display element. Electronic devices to which this embodiment is applicable can be information devices such as smartphones or personal computers. Alternatively, electronic devices can be office equipment such as printers or copiers, medical devices such as X-ray imaging devices or endoscopes, industrial equipment such as robots or semiconductor manufacturing equipment, or transportation equipment such as vehicles, airplanes, or ships.

[0300] Example 11

[0301] As Example 11, an embodiment in which a tantalum oxide film with a hydrogen content within a predetermined range is applied to an imaging element will be described. It should be noted that the amount within the predetermined range refers to the content (at%) described in the above embodiment.

[0302] Reference Figure 29 The solid-state imaging element 900 of Embodiment 11 is described. The solid-state imaging element 900 is a back-illuminated CMOS sensor. However, the implementation of the present invention is not necessarily limited to a back-illuminated CMOS sensor. That is, embodiments of the present invention can be solid-state imaging elements in which a tantalum oxide film with a hydrogen content within a predetermined range is disposed in the optical path of the imaging light.

[0303] Semiconductor substrate 2 has a first surface on which light is incident and a second surface opposite to the first surface. For example, a silicon substrate can be used as semiconductor substrate 2. Semiconductor substrate 2 includes a photoelectric conversion unit 600 and a first transistor 410. The photoelectric conversion unit 600 performs photoelectric conversion on the incident light and accumulates a first charge. The first transistor 410 includes a first gate 390 located on the second surface. Semiconductor substrate 2 includes a second transistor 310, which includes a second gate 290 located on the second surface. The first transistor 410 is an NMOS transistor, which consists of a source 400, a drain 380, and a first gate 390, and is disposed in a well (p-type well 360) where holes are the primary charge carriers.

[0304] In the semiconductor substrate 2, a separation region 120 is provided between the first transistor 410 and the second transistor 310 in a planar view. Therefore, charge movement between the first transistor 410 and the second transistor 310 can be suppressed. The separation region 120 is embedded in a trench formed in the semiconductor substrate 2 and is made of one of the following materials: an insulator, polysilicon, or a silicon oxide film coated thereon. Alternatively, the separation region 120 may be a metal embedded in the trench.

[0305] This embodiment includes a pixel region 10, in which a plurality of photoelectric conversion units 600 and a plurality of first transistors 410 are arranged in a two-dimensional manner, and the plurality of first transistors 410 are electrically connected to the plurality of photoelectric conversion units 600 respectively. Furthermore, a plurality of second transistors 310 are provided outside the pixel region 10. It should be noted that the semiconductor substrate 2 may include a single photoelectric conversion unit 600, a single first transistor 410, and a single second transistor 310.

[0306] The photoelectric conversion unit 600 is, for example, a photodiode. Specifically, the photoelectric conversion unit 600 includes an n-type semiconductor portion and a p-type semiconductor portion on the upper surface of the semiconductor substrate 2, which are part of the substrate 2.

[0307] Pixel region 10 includes an effective pixel region 11 containing multiple photoelectric conversion units 600, and a light-shielding pixel region (optical black) 12. Light-shielding walls can be provided in the effective pixel region 11 to separate each pixel. Therefore, color mixing between pixels can be reduced. Outside the light-shielding pixel region 12 is a peripheral circuit region 13, which typically does not provide a repeating arrangement structure like that of pixel region 10.

[0308] The plurality of second transistors 310 are arranged in the peripheral circuit region 13. For example, the second transistors 310 may be located outside the region in which the plurality of lenses included in the microlens array 190 and the color filter 180 are arranged in a two-dimensional arrangement in the plan view, or they may be located in a region outside the separation region 120.

[0309] In the peripheral circuit area 13, a vertical scanning circuit, a horizontal scanning circuit, a timing generator, and an output section are provided. Furthermore, a signal processing section, including a signal correction section and an analog-to-digital converter, can be provided.

[0310] The second transistor 310 includes an NMOS transistor, which includes a second gate 290 located on a second surface of the semiconductor substrate 2, and a source 280 and a drain 300 disposed in a p-type well 360. The well 360, where the source 280 and drain 300 of the second transistor 310 are disposed, serves as part of the lower surface and part of the upper surface of the semiconductor substrate 2. For example, the well 360 is continuously disposed from the first surface to the second surface of the semiconductor substrate 2. The peripheral circuit region 13 may also include a PMOS transistor 350, which includes a gate 330 located on the second surface and a source 320 and a drain 340 disposed in an n-type well 370.

[0311] The first optical film 130 constitutes an anti-reflection structure. Furthermore, the first optical film 130 can be a fixed-charge film having a first polarity (e.g., negative polarity) of fixed charge, and has the function of fixing a second polarity (e.g., positive polarity) of charge in the semiconductor substrate 2. On the first surface of the semiconductor substrate 2, the first optical film 130 is disposed in a region in the planar view that overlaps at least with the photoelectric conversion unit 600 (as a photoelectric structure) and the second transistor 310. Here, "fixed charge" refers to a charge existing in the film and in a fixed state that is not moved by an electric field, etc. The first optical film 130 is disposed at least in the optical path from the imaging light to the photoelectric conversion unit 600.

[0312] In this embodiment, a first optical film 130 is disposed on a first surface of the semiconductor substrate 2 to continuously cover the area directly above the plurality of photoelectric conversion units 600, the plurality of first transistors 410, and the plurality of second transistors 310. That is, in a plan view, the first optical film 130 is continuously disposed to overlap with the plurality of photoelectric conversion units 600, the plurality of first transistors 410, and the plurality of second transistors 310. The first optical film 130 may, for example, be disposed on the entire surface of the pixel region 10 and the peripheral circuit region 13 on the upper surface of the semiconductor substrate 2. Therefore, it is not necessary to remove the first optical film 130 by etching or the like, thus suppressing damage to the semiconductor substrate 2.

[0313] It should be noted that the first optical film 130 is a region that overlaps with the photoelectric conversion unit 600 and the second transistor 310 in the plan view and is disposed on the first surface of the semiconductor substrate, and it may be partially disposed on the first surface of the semiconductor substrate. The first optical film 130 is preferably disposed on the entire first surface of the pixel area and the peripheral circuit area.

[0314] In the solid-state imaging element 900 of Embodiment 11, the first optical film 130 comprises a tantalum oxide film with a hydrogen content within a predetermined range. Since the tantalum oxide film has low light absorption and high transmittance, it can suppress the loss of imaging light reaching the photoelectric conversion unit 600. It should be noted that the first optical film 130 can be a single-layer film or a stack of multiple layers. An example of a preferred configuration of the first optical film 130 includes a configuration in which an aluminum oxide film and a tantalum oxide film are sequentially stacked from the semiconductor substrate 2 side, wherein the hydrogen content of the tantalum oxide film is within a predetermined range.

[0315] The first optical film 130 is preferably a stack of multiple layers with different refractive indices. In this embodiment, the optical film 130 consists of the following layers stacked sequentially from the semiconductor substrate 2 side: a layer having a first refractive index lower than that of the semiconductor substrate 2, and a layer having a second refractive index lower than that of the first refractive index. Therefore, total internal reflection on the first optical film 130 can be suppressed, and thus light can be effectively incident on the photoelectric conversion unit 600.

[0316] Although in this embodiment a tantalum oxide film with a hydrogen content within a predetermined range is used for the first optical film 130, the tantalum oxide film can be used for different films disposed in the optical path of the imaging light of the photoelectric conversion unit 600. It should be noted that for the parts of the solid-state imaging element in this embodiment other than the use of a tantalum oxide film with a hydrogen content within a predetermined range, please refer to Japanese Patent Publication No. 2019-212737.

[0317] It should be noted that when manufacturing the solid-state imaging element of this embodiment, ultraviolet light reflection on the tantalum oxide film serving as the substrate is suppressed during the ultraviolet light exposure step for forming the color filter 180 and the microlens array 190. In other words, the halo effect of ultraviolet light that reduces pattern accuracy is suppressed, thus achieving the effect of forming the color filter 180 and the microlens array 190 with high shape accuracy.

[0318] The imaging element of this embodiment can be suitably used in imaging devices, such as various cameras including interchangeable lens cameras and integrated lens cameras, camera modules for smartphones and moving objects (e.g., vehicles and drones), and ultraviolet cameras. The images obtained by the imaging element can be still images or moving images. The imaging device may include a light source (e.g., an ultraviolet light source).

[0319] According to this embodiment, for example, by making the imaging element sensitive not only to blue light but also to ultraviolet light used for blue images, the sensitivity of the imaging element to visible light imaging can be enhanced. Furthermore, the imaging element can be an imaging element that includes a light-receiving part (pixel) for detecting ultraviolet light in addition to light-receiving parts (pixels) of various colors (R, G, and B), or an imaging element that only includes pixels for ultraviolet light imaging. In the imaging element of this embodiment, ultraviolet light can be guided to the light-receiving part with minimal loss, thus achieving high sensitivity.

[0320] The imaging element in this embodiment can be used for purposes such as: imaging a target object illuminated by ultraviolet light (e.g., J-rays) to detect minute scratches and defects that are difficult to detect with visible light, or classifying plastic materials. Alternatively, the imaging element can be used for purposes such as: imaging power facilities to inspect for discharges or identify the location of discharges.

[0321] Modified embodiments of the third and fourth implementation schemes

[0322] It should be noted that the present invention is not limited to the above-described embodiments and examples, and can be modified in various ways within the technical concept of the present invention. For example, multiple embodiments can be combined. Furthermore, some elements in the embodiments can be omitted or replaced. Additionally, new content can be added to the embodiments.

[0323] The number of layers, the thickness of each layer, and the material used for the low-refractive-index layer in the optical structure constituting the present invention (e.g., an anti-reflection structure or a reflective structure) are not limited to these embodiments. In short, it is sufficient as long as the optical structure includes a high-refractive-index layer in the optical path of the optical element, consisting of tantalum oxide with a hydrogen content of 1.0 at% or more and less than 10.0 at% as part of the hydrogen content. In particular, an optical structure comprising a tantalum oxide film with a hydrogen content of 3.0 at% or more and less than 9.0 at% is preferred.

[0324] The optical structure for implementing the present invention is preferably positioned in the optical path of light with wavelengths in the range of 290 nm to 500 nm, for example, but light outside the above range can also be incident on the optical path.

[0325] Optical elements comprising the high-refractive-index film according to the invention can be used in optical devices, such as exposure apparatuses, various cameras, and interchangeable lenses. In addition to multiple optical components comprising an optical element coated with a tantalum oxide film containing a predetermined amount of hydrogen, these optical devices may also include a holding portion (e.g., a lens mount) that holds the multiple optical components. In exposure apparatuses including ultraviolet light sources (e.g., for manufacturing flat panel displays), the exposure performance of the exposure apparatus can be improved by providing an anti-reflection structure of the embodiment on the lens and / or a reflective structure of the embodiment on the mirror.

[0326] Tantalum oxide films, as high-refractive-index films, can be applied not only to optical components but also to electronic components such as transistors or capacitors. For example, tantalum oxide films can be used as gate insulating films for semiconductor components such as MOSFETs or TFTs, or as insulating films (dielectric films) between electrodes in capacitor components. In these electronic components, low leakage current can be achieved by setting the hydrogen content of amorphous tantalum oxide to 1.0 at% or higher, thereby enabling high-performance electronic components. It should be noted that setting the hydrogen content of crystalline (single-crystal or polycrystalline) tantalum oxide films to 1.0 at% or higher has not yielded any advantages compared to cases with a hydrogen content less than 1.0 at%. Tantalum oxide films can also be used as gate insulating films for at least one of the various transistors in the aforementioned solid-state imaging element 900. High-dielectric films are widely used as gate insulating films for various transistors and can be implemented in various semiconductor components (such as memory, processors, and logic ICs) and various electronic devices (such as smartphones and personal computers).

[0327] The electronic devices applicable to this implementation scheme can be information devices such as smartphones or personal computers, or communication devices such as modems or routers. Alternatively, the electronic devices can be office equipment such as printers or copiers, medical equipment such as X-ray imaging devices or endoscopes, industrial equipment such as robots or semiconductor manufacturing equipment, or transportation equipment such as vehicles, airplanes, or ships.

[0328] The above embodiments can be appropriately modified within the technical concept. For example, multiple embodiments can be combined. Furthermore, elements of at least one embodiment can be omitted or replaced. Additionally, new content can be added to at least one embodiment.

[0329] Furthermore, the disclosure in this specification includes not only what is described herein, but also all items that can be understood from this specification and its accompanying drawings. Additionally, the disclosure in this specification includes complementary sets of concepts described herein. Therefore, if this specification contains, for example, a description indicating "A is B," then even if a description indicating "A is not B" is omitted, it can be said that this specification discloses a description indicating "A is not B." This is because, in the presence of a description indicating "A is B," the premise "A is not B" is taken into consideration.

[0330] Furthermore, regarding the specific numerical ranges described as examples in this specification, the description of e to f (where e and f are numerical values) means above e and / or below f. Additionally, regarding the aforementioned specific numerical ranges, when simultaneously describing the ranges from i to j and m to n (where i, j, m, and n are numerical values), the pairing of lower and upper limits is not limited to the pairing of i and j or m and n. For example, multiple pairs of lower and upper limits can be considered together. That is, when simultaneously describing the ranges from i to j and m to n, the ranges from i to n and m to j can be considered as long as there is no contradiction. Furthermore, above e means equal to or greater than e (exceeding e), and values ​​greater than e can be used instead of e. Additionally, below f means equal to or less than f (not reaching f), and values ​​less than f can be used instead of f.

[0331] Other implementation plans

[0332] While the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. An optical element comprising: matrix; and Optical structures formed on a substrate The optical structure comprises alternating layers of a first type and layers of a second type. The membrane constituting each of the layers of the first type comprises: Oxides of group 3-11 transition metals; and hydrogen; The sum of the transition metal content and the oxygen content in the membrane is higher than the hydrogen content in the membrane, and each content is expressed as an atomic percentage. The hydrogen content is 1.0 at% or higher, and The film is amorphous.

2. The optical element according to claim 1, wherein, The hydrogen content is equal to or less than half of the transition metal content.

3. The optical element according to claim 1, wherein, The oxide of the transition metal is an oxide of a Group 4 or Group 5 transition metal.

4. The optical element according to claim 3, wherein, The oxide of the transition metal is an oxide of a transition metal from the 5th or 6th period.

5. The optical element according to claim 1, wherein, The oxide of the transition metal includes tantalum oxide.

6. The optical element according to claim 5, wherein, The hydrogen content is less than 10.0 at.

7. The optical element according to claim 5, wherein, The hydrogen content is 3.0 at% or higher.

8. The optical element according to claim 5, wherein, The absorption rate of light with a wavelength of 313nm is less than 0.40%, and the refractive index of light with a wavelength of 313nm is greater than 2.

40.

9. The optical element according to claim 1, wherein, The membrane also contains Group 18 elements, and the content of Group 18 elements in the membrane is lower than the hydrogen content.

10. The optical element according to claim 1, wherein, The refractive index of the second type of layer is lower than that of the first type of layer.

11. An optical element comprising: matrix; and Optical structures formed on a substrate The film constituting the optical structure comprises: Oxides of group 3-11 transition metals; Hydrogen; and Element of the 18th group, The sum of the transition metal content and the oxygen content in the membrane is higher than the hydrogen content in the membrane, and each content is expressed as an atomic percentage. The hydrogen content is 1.0 at% or higher. The sum of the content of the transition metal, the oxygen content, the hydrogen content, and the content of Group 18 elements in the membrane is 99.0 at% or more, and The film is amorphous.

12. The optical element according to claim 11, wherein, The hydrogen content is lower than the transition metal content and the oxygen content, but higher than the group 18 element content.

13. The optical element according to claim 11, wherein, The oxide of the transition metal contains hafnium oxide.

14. The optical element according to claim 13, wherein, The hydrogen content is below 16.0 at%.

15. The optical element according to claim 13, wherein, The hydrogen content is 6.0 at% or higher.

16. The optical element according to claim 13, wherein, The hafnium oxide contains zirconium, and the zirconium content is above 0.05 at% and below 0.5 at%.

17. The optical element according to claim 13, wherein, It has a refractive index of 2.15 or higher for light with a wavelength of 280 nm, and an absorption rate of less than 0.2% for light with a wavelength of 280 nm.

18. The optical element according to any one of claims 1 to 17, wherein, The argon content in the membrane is above 0.5 at% and below 5.0 at%.

19. The optical element according to any one of claims 1 to 17, wherein, The silicon content, carbon content, and nitrogen content in the membrane are all less than 0.5 at.

20. The optical element according to any one of claims 1 to 17, wherein, The thickness of the film is greater than 10 nm and less than 1000 nm.

21. The optical element according to any one of claims 1 to 17, wherein, The optical element is a lens.

22. The optical element according to any one of claims 1 to 17, wherein, The optical structure has an anti-reflection structure.

23. The optical element according to any one of claims 1 to 17, wherein, The optical structure has a reflective structure.

24. The optical element according to any one of claims 1 to 17, wherein, The substrate has a photoelectric structure.

25. An optical device comprising: Multiple optical elements; and A holding section is configured to hold the plurality of optical elements. in, The plurality of optical elements include the optical elements according to any one of claims 1 to 17.

26. An optical device comprising: The optical element according to any one of claims 1 to 17; and A light source configured to generate light to illuminate the membrane.

27. The optical device according to claim 26, wherein, The light has at least one wavelength in the range of 280 nm to 380 nm.

28. An optical device configured as an exposure apparatus, comprising at least one of the following configurations: An illumination optics system configured to illuminate a photomask; A projection optics system configured to project the pattern of the mask onto the processing target; A correction optical system configured to correct aberrations in the projection optical system; and An alignment mechanism configured to align the mask and the processing target. The membrane included in the aforementioned structure comprises: Oxides of group 3-11 transition metals; and hydrogen; in, The sum of the transition metal content and the oxygen content in the membrane is higher than the hydrogen content in the membrane. Each content is expressed as an atomic percentage. Wherein, the hydrogen content is 1.0 at% or higher, and The film is amorphous.

29. The optical device according to claim 28, wherein, The membrane includes elements from Group 18. The hydrogen content is higher than the content of the Group 18 elements. Wherein, the hydrogen content is equal to or less than half of the transition metal content, and The oxygen content is higher than the transition metal content.

30. The optical device according to claim 29, wherein, The content of the group 18 element is above 0.5 at% and below 5.0 at%.

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