Optical elements, optical instruments

Abstract

To provide technique advantageous for controlling property of a film including a metal oxide.SOLUTION: A film is provided, including an amorphous transition metal oxide as a principal component and having a hydrogen content of 1.0 atom% or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a film comprising a metal oxide. [Background technology]

[0002] Metal oxides are being considered for application in the fields of optical elements, electrical elements, and semiconductor elements.

[0003] In various optical devices such as exposure apparatuses, optical elements are coated with optical films in order to improve optical characteristics such as anti-reflection characteristics or reflection characteristics. In capacitive elements and semiconductor elements, insulating films are used to insulate capacitive electrodes and gate electrodes from other elements.

[0004] As optical equipment is required to have high performance, the number of optical elements used in the equipment tends to increase, and the number of optical surfaces that need to be coated with optical films also tends to increase. In addition, the optical films to be coated are not necessarily composed of a single layer, but may be composed of multiple layers, so the total number of layers provided tends to increase. In the field of optical elements, attempts have been made to coat optical members such as lenses and filters with films containing metal oxides as optical films.

[0005] Patent Document 1 describes that hydrogen is contained in a dielectric multilayer film used in an optical element in order to reduce deterioration of the dielectric multilayer film. The hydrogen contained in the dielectric film compensates for lattice defects that cause light absorption, thereby extending the life of the dielectric multilayer film. Examples of dielectric multilayer films that contain hydrogen include SiO2, Al2O3, TiO2, Ta2O5, HfO2, and ZrO2.

[0006] Patent Document 1 discloses a technique for using a dielectric film in which hydrogen is contained in SiO2 or TiO2 to provide a high-strength dielectric multilayer film for optical elements. Hydrogen-containing Ta2O5, HfO2, Al2O3, and ZrO2 are suggestively listed as dielectric materials other than SiO2 and TiO2, but no specific information is disclosed.

[0007] Patent Document 2 discloses a technique for reducing the internal stress of a coating by adding 1 at % to 10 at % of silicon in order to suppress light absorption and scattering when hafnium oxide is used as an optical film.

[0008] In the field of semiconductor devices, attempts have been made to use a film containing hafnium oxide as a gate insulating film for transistors. When a high-dielectric constant film containing hafnium oxide is used as a gate insulating film for transistors, crystallization occurs due to high-temperature processing during the manufacturing process, and there is a problem that leakage current increases through crystal grain boundaries or defect levels.

[0009] Patent Document 3 discloses a technology for forming a silicon-containing high dielectric constant film by diffusing silicon into hafnium oxide in order to suppress an increase in leakage current caused by crystallization of a high dielectric constant material when a high-temperature process is performed after the formation of a gate insulating film.

[0010] Patent Document 4 proposes a reflective optical element equipped with an optical film with a design central wavelength of 400 nm. Materials used for the high refractive index layer of the optical film coated on the reflective optical element include tantalum oxide (Ta2O5), niobium oxide (NbO5), titanium oxide (TiO2), zirconium oxide (ZrO2), zinc oxide (ZnO), hafnium oxide (HfO2), aluminum nitride (AlN), and silicon nitride (SiN).

[0011] Patent document 5 discloses a nonlinear driving element that uses metallic tantalum as the lower metal, tantalum oxide as the insulating film, and a transparent conductive film as the upper metal, and in which the concentration of hydrogen atoms contained in the tantalum oxide as the insulating film is less than 1 atomic %. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 10-217377 [Patent Document 2] Special Publication No. 2012-506950 [Patent Document 3] JP 2006-165589 A [Patent Document 4] JP 2017-83789 A [Patent Document 5] Japanese Patent Application Publication No. 7-311393 Summary of the Invention [Problem to be solved by the invention]

[0013] In the field of optical elements, there has been a demand for optical films with high performance. In the field of electrical elements, there has been a demand for insulating films with high performance. Therefore, an object of the present invention is to provide a technique that is advantageous in controlling the properties of films containing metal oxides. [Means for solving the problem]

[0014] A first aspect of the means for solving the above problems is a film that is an optical film, comprising an amorphous transition metal oxide as a main component, containing argon, and having a hydrogen content of 1.0 at % or more, the transition metal oxide being an oxide of a transition metal of Groups 3 to 11.

[0015] A second aspect of the means for solving the above problem is a film comprising an amorphous transition metal oxide as a main component, containing argon, and having a hydrogen content of 1.0 at% or more, the transition metal oxide being an oxide of a transition metal of Groups 3 to 11, and the sum of the transition metal content, oxygen content, hydrogen content, and argon content is 99.0 at% or more. Effect of the Invention

[0016] According to the present invention, it is possible to provide a technique that is advantageous in controlling the properties of a film containing a metal oxide. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view of an optical element according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a sputtering film formation apparatus used in the manufacture of the optical element according to the first embodiment. [Diagram 3] 1 is a graph showing the light absorptance characteristics versus hydrogen content of a hafnium oxide film. [Figure 4] 1 is a graph showing the refractive index characteristics versus hydrogen content of a hafnium oxide film. [Diagram 5] 4 is a graph showing the wavelength dependence of light absorption in Example 1 and Example 3 of the first embodiment. [Figure 6] 4 is a graph showing the wavelength dependence of the refractive index of Example 1 and Example 4 of the first embodiment. [Figure 7] FIG. 2 is a diagram showing an X-ray diffraction pattern of the hafnium oxide film of Example 1 of the first embodiment. [Figure 8] FIG. 2 is a diagram showing an X-ray diffraction pattern of a hafnium oxide film of Comparative Example 1 of the first embodiment. [Figure 9] FIG. 4 is a cross-sectional view showing layer configurations of Example 5 and Example 6 of the first embodiment. [Figure 10] 13 is a graph showing the reflectance characteristics of the optical structures (antireflection structures) of Example 5 and Example 6 of the first embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing the layer configurations of Examples 7 and 8 of the first embodiment. [Figure 12] 13 is a graph showing the reflectance characteristics of the optical structures (reflection structures) of Example 7 and Example 8 of the first embodiment. [Figure 13] FIG. 13 is a schematic cross-sectional view for explaining a semiconductor device including a CMOS transistor according to Example 11 of Embodiment 2. [Figure 14] FIG. 23 is a schematic cross-sectional view for explaining a semiconductor device including a thin film transistor according to Example 12 of Embodiment 2. [Figure 15] FIG. 23 is a schematic partial cross-sectional view for explaining a back-illuminated imaging element according to Example 13 of Embodiment 2. [Figure 16] FIG. 5 is a schematic cross-sectional view of an optical element according to a third embodiment. [Figure 17] FIG. 11 is a schematic diagram of a sputtering film formation apparatus used in manufacturing an optical element according to embodiment 3. [Figure 18] 1 is a graph showing light absorption characteristics versus hydrogen content of a tantalum oxide film. [Figure 19] 13 is a graph showing the wavelength dependence of light absorption in Example 4, Example 5, and Comparative Example 1 of the third embodiment. [Figure 20] 11 is a cross-sectional view showing layer configurations of Example 6, Example 7, and Comparative Example 3 of the third embodiment. FIG. [Figure 21] 13 is a graph showing the wavelength dependence of reflectance in Example 6, Example 7, and Comparative Example 3 of the third embodiment. [Figure 22] FIG. 22 is a partially enlarged view of the short wavelength side of the graph in FIG. 21. [Figure 23] 13 is a graph showing the wavelength dependence of transmittance in Example 6, Example 7, and Comparative Example 3 of the third embodiment. [Figure 24] 1 is a graph showing the relationship between the refractive index and hydrogen content for light with a wavelength of 365 nm. [Diagram 25] 11 is a cross-sectional view showing layer configurations of Example 8 and Comparative Example 4 of the third embodiment. FIG. [Figure 26] 13 is a graph showing the wavelength dependence of reflectance in Example 8 of the third embodiment and Comparative Example 4. [Figure 27] 10 is a graph showing an X-ray diffraction pattern of the tantalum oxide film of the third embodiment. [Figure 28] FIG. 16 is a schematic diagram showing the configuration of an exposure apparatus according to a tenth example of the third embodiment. [Figure 29] FIG. 13 is a schematic cross-sectional view of a solid-state imaging element according to an eleventh example of the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. A number of embodiments will be described in order, and specific examples will be given for each embodiment. The film of the embodiment contains an amorphous transition metal oxide as a main component, and has a hydrogen content of 1.0 at% or more. In an element having this film, the film is disposed on a substrate provided in the element. Amorphous (or amorphous) means that when the film to be measured is irradiated with X-rays or electron beams at a small incident angle of about 0.5 degrees and a diffraction pattern is observed, no clear diffraction peak is detected, in other words, a halo pattern is observed. Therefore, the amorphous state in this case does not necessarily exclude a state in which a material in a microcrystalline state is contained. Here, "at%" means "atomic percentage", which is the ratio of a specific atom number to the total number of atoms in the target composition.

[0019] Hereinafter, one particular transition element of interest will be referred to as transition metal T. A transition metal oxide is a compound of transition metal T and oxygen. Transition metal T is an element in groups 3 to 11 of the periodic table, and is a transition element. Unlike typical elements, in transition elements in which the d orbital or f orbital is not a closed shell, it is believed that the hydrogen level and oxygen level affect the film properties.

[0020] Examples of oxides of transition elements 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).

[0021] Examples of oxides of metals belonging to the fifth period (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).

[0022] Examples of oxides of transition elements belonging to the 6th period (third transition elements; 5d and 4f transition elements) include lanthanum oxide (La2O3; lanthanoid), cerium oxide (CeO2; lanthanoid), samarium oxide (Sm2O3; lanthanoid), ytterbium oxide (Yb2O3; lanthanoid), hafnium oxide (HfO2; group 4), tantalum oxide (Ta2O5; group 5), and tungsten oxide (WO3; group 6).

[0023] Typically, an oxide of a transition metal of Groups 3 to 6 can be used. In particular, an oxide of a transition metal of Groups 4 or 5 is preferable. Also, typically, an oxide of a transition metal of Periods 4 to 6 can be used. In particular, an oxide of a transition metal of Periods 5 or 6 is preferable.

[0024] In the transition metal oxide, the content J (at%) of the transition metal T, the content K (at%) of the oxygen, and the content L (at%) of the hydrogen are defined, and J, K, and L>0. The content M (at%) of the impurity A and the content N (at%) of the impurity B in the transition metal oxide are also defined. M and N≧0. Here, a case is illustrated in which the transition metal oxide contains two elements other than the transition metal, oxygen, and hydrogen. That is, the transition metal oxide contains five elements. However, the transition metal oxide may contain one element other than the transition metal, oxygen, and hydrogen, or three or more elements. The transition metal oxide may contain four elements, or six or more elements.

[0025] A film mainly composed of an oxide of a transition metal T means that the sum of the transition metal T content J and the oxygen content K is greater than the respective contents L, M, and N of elements other than the transition metal T and oxygen contained in the film (J+K>L, J+K>M, J+K>N). Since the transition metal oxide film of this embodiment contains hydrogen in addition to the transition metal and oxygen, the sum of the transition metal T content J 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 transition metal T content J and the oxygen content K is 99.0 at% or less (J+K≦99.0 at%).

[0026] Let the stoichiometric composition of the oxide of a transition metal T be T j O k If k ≥ 1, then J×(k - 0.5) / j < K < J×(k + 0.5) / j is possible, and if k ≥ 2, then J×(k - 1) / j < K < J×(k + 1) / j is possible. It is preferable that the sum of the content J of the transition metal T and the content K of oxygen in the transition metal oxide film is greater than the sum of the contents L, M, and N of all elements other than the transition metal T and oxygen contained in the transition metal oxide film (J + K > L + M + N). In this case, J + K will be greater than 50 at%.

[0027] Hydrogen in the transition metal oxide film can typically exist in a form bonded to the transition metal T of the transition metal oxide so as to fill the oxygen vacancies of the transition metal oxide, or in a form bonded to the oxygen of the transition metal oxide. Therefore, the hydrogen content L of the transition metal oxide film can be smaller than the oxygen content K (L < K). Also, the hydrogen content L of the transition metal oxide film can be smaller than the content J of the transition metal T of the transition metal oxide film (L < J). The fact that the content J of the transition metal T in the transition metal oxide film is greater than the hydrogen content L (J > L) is advantageous for obtaining a dense transition metal oxide film. The physical properties of a denser transition metal oxide film generally deviate further from the physical properties of a vacuum. For example, the refractive index of a denser transition metal oxide film becomes higher by deviating from the physical properties of a vacuum (refractive index = 1.0). For obtaining a dense transition metal oxide film, it is preferable that the hydrogen content L is less than or equal to half of the content J of the transition metal T (L ≤ J / 2).

[0028] In the stoichiometric composition T j O k of the oxides of many transition elements, j ≤ k, especially j < k. From this, the oxygen content K is greater than the content J of the transition metal T (K > J). As described above, the hydrogen content L is smaller 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.

[0029] Since the composition of the amorphous transition metal oxide film is amorphous, it can typically deviate from the stoichiometric composition. That is, for the stoichiometric composition T j O k of the transition metal oxide, the ratio K / J of the content J of the transition metal to the content K of oxygen can be different from k / j. For example, when hydrogen in the film is present in a form that binds to the transition metal of the transition metal oxide so as to fill the oxygen vacancies of the transition metal oxide, K / J > k / j can occur. Also, for example, when hydrogen in the film is present in a form that binds to the oxygen of the transition metal oxide, K / J < k / j can occur.

[0030] Elements other than transition metals, oxygen, and hydrogen that can be contained in the transition metal oxide film can be either transition elements or typical elements. However, it is better if elements other than transition metals, oxygen, and hydrogen are not contained as much as possible. Hereinafter, impurities A and B that can be contained in the transition metal oxide film will be described.

[0031] The content M (at%) of impurity A is preferably smaller than the content L of hydrogen (M < L), but it may also be larger than the content L of hydrogen (M > L). The content M of impurity A may be 0.5 at% or more and 5.0 at% or less. If impurity A is an element of Group 18 of the periodic table (noble gas), it is chemically inert, so it is easy to control the characteristics of the transition metal oxide film. Impurity A is typically argon, but it may be krypton or xenon instead of argon.

[0032] The content N (at%) of impurity B described above is smaller than the content M of impurity A (N < M). Also, the content N of impurity B is smaller than the content L of hydrogen (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.

[0033] Impurity B can be a metal element, a transition element, or a transition element of the same group as transition metal T. If impurity B is of the same group as transition metal T in the periodic table, it is easier to control the properties of the transition metal oxide film due to their chemical similarity. For example, if transition metal T is hafnium, impurity B can be zirconium, and if transition metal T is zirconium, impurity B can be hafnium. For example, if transition metal T is tantalum, impurity B can be niobium, and if transition metal T is niobium, impurity B can be tantalum. For example, if transition metal T is tungsten, impurity B can be molybdenum, and if transition metal T is molybdenum, impurity B can be tungsten. For example, if transition metal T is yttrium, impurity B can be a lanthanide, and if transition metal T is a lanthanide, impurity B can be another lanthanide or yttrium.

[0034] The content of each of the typical elements excluding oxygen, hydrogen and noble gases in the transition metal oxide film is preferably less than 1.0 at%, more preferably 0.5 at% or less, and even more preferably 0.1 at% or less. The content of each of the typical elements excluding oxygen, hydrogen and noble gases in the transition metal oxide film may be below the detection limit. Here, the typical elements are elements of groups 1, 2 and 12 to 18 of the periodic table, and the typical elements excluding noble gases are elements of groups 1, 2 and 12 to 17. The content may be 0. The content of each of the typical elements excluding 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 even more preferably 0.1 at% or less.

[0035] The total content of all impurities, excluding the transition metal T, oxygen, hydrogen, and impurity A, is preferably less than 1.0 at%. In other words, it is preferable that the sum of the content J of the transition metal T, the content K of the oxygen, the content L of the hydrogen, and the content M of the impurity A is greater than 99.0 at% (J+K+L+M>99.0 at%). It is more preferable that the total content of all impurities, excluding the transition metal T, oxygen, hydrogen, and impurity A, is 0.5 at% or less. In other words, it is preferable that the sum of the content J of the transition metal T, the content K of the oxygen, the content L of the hydrogen, and the content M of the impurity A is 99.5% or more (J+K+L+M≧99.5 at%). It is more preferable that the total content of all impurities, excluding the transition metal T, oxygen, hydrogen, impurity A, and impurity B, is 0.1 at% or less. In other words, it is preferable that the sum of the content J of the transition metal T, the content K of the oxygen, the content L of the hydrogen, the content M of the impurity A, and the content N of the impurity B is 99.9% or more (J+K+L+M+N≧99.9at%). In the transition metal oxide film, all elements except for the transition metal, oxygen, hydrogen, impurity A, and impurity B may be below the detection limit. In the transition metal oxide film, all elements except for the transition metal, oxygen, hydrogen, impurity A, and impurity B may not be included.

[0036] The transition metal content J (at%), oxygen content K (at%), hydrogen content L (at%), impurity A content M (at%), and impurity B content N (at%) satisfy at least one of J+K>L+M+N, J>L, K>L, L>M, and M>N. L≧1.0(at%), N<1.0(at%), and J+K+L+M≧99.0at% may be satisfied.

[0037] Stoichiometric composition of transition metal oxides T j O kFor K / J ≈ k / j and J + K + L ≈ 100, when L < J, L < 100×j / (2×j + k); when L ≤ J / 2, L ≤ 100×j / (3×j + 2×k). If j = 1 and k = 2, to satisfy L < 100×j / (2×j + k), L < 25 at%. If j = 1 and k = 3, to satisfy L < 100×j / (2×j + k), L < 14 at%. If j = 2 and k = 3, to satisfy L < 100×j / (2×j + k), L < 28 at%. If j = 2 and k = 5, to satisfy L < 100×j / (2×j + k), L < 22 at%. If j = 1 and k = 2, to satisfy L ≤ 100×j / (3×j + 2×k), L ≤ 14 at%. If j = 1 and k = 3, to satisfy L ≤ 100×j / (3×j + 2×k), L ≤ 11 at%. If j = 2 and k = 3, to satisfy L ≤ 100×j / (3×j + 2×k), L ≤ 16.0 at%. If j = 2 and k = 5, to satisfy L ≤ 100×j / (3×j + 2×k), L ≤ 12 at%.

[0038] This transition metal oxide film can be used as an optical film. An optical film is a film that utilizes the action of light, and the action of light includes reflection, transmission, absorption, refraction, scattering, excitation, etc. By containing 1.0 at% or more of hydrogen in the amorphous film, the refractive index and extinction coefficient (absorption rate) of the film at a specific wavelength can be significantly controlled. The transition metal oxide as an optical film only needs to be optically usable when formed into a film. Typically, oxides of transition metals in Groups 3 - 6 can be used. In particular, oxides of transition metals in Group 4 or 5 are preferred. Also, typically, oxides of transition metals in the 4th - 6th periods can be used. In particular, oxides of transition metals in the 5th or 6th periods are preferred.

[0039] The wavelength λ contained in the light used for the optical film is a wavelength at which the optical properties of the film can change significantly depending on the hydrogen content in the film. This wavelength λ may be in the ultraviolet range (less than 400 nm), the visible range (400 to 800 nm), or the infrared range (more than 800 nm). The light used for the optical film may contain light of a wavelength at which the optical properties of the film do not change significantly depending on the hydrogen content in the film.

[0040] The optical element having the optical film may be an optical element whose optical characteristics do not change due to an external action, or an optical element whose optical characteristics change due to an external action. The former optical element is a lens, a mirror, or a filter, and the optical film can be used as an anti-reflection film, a reflection film, or a light absorbing film. The latter optical element can be, for example, a chromic element that utilizes the chromic characteristics of the optical film. For example, tungsten oxide, molybdenum oxide, titanium oxide, chromium oxide, cobalt oxide, and nickel oxide can have chromic characteristics. The external action in the chromic element can be electrical (electrochromic) or chemical (gaschromic).

[0041] The optical element having the optical film constitutes an optical instrument. The optical instrument may have a light source that emits light used for the optical film in addition to the optical element having the optical film. In an optical instrument having a light source that emits light including a specific wavelength λ, the hydrogen content L may be adjusted when adjusting the characteristics of the optical film of the optical element to match the wavelength λ. Of course, the light used for the optical film may be light irradiated from outside the optical device.

[0042] The optical film (transition metal oxide film) in the optical element constitutes the whole or part of the optical structure on the substrate. When the transition metal oxide film constitutes the whole of the optical structure on the substrate, the optical structure on the substrate is a single layer of the transition metal oxide film. When the transition metal oxide film constitutes a part of the optical structure on the substrate, the optical structure on the substrate is a laminate including a plurality of transition metal oxide films. A typical optical structure is a laminate in which a transition metal oxide film and another optical film are laminated. The other optical film laminated on the transition metal oxide film may have a higher refractive index than the transition metal oxide film, or may have a lower refractive index. Since the transition metal oxide film has a relatively high refractive index, it is desirable to use the transition metal oxide film as a high refractive index film, and the other optical film laminated on the transition metal oxide film is a low refractive index film having a lower refractive index than the transition metal oxide film. The other optical film laminated on the transition metal oxide film may be an oxide film of a typical element. In this embodiment, the refractive index of the transition metal oxide film can be adjusted by the hydrogen content of the transition metal oxide film.

[0043] The transition metal oxide film of the embodiment is suitable for an optical structure in which multiple transition metal oxide films and another optical film are alternately laminated. Here, the alternately laminated first type film and second type film 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 layers of film are required for the first type film and the second type film to be alternately laminated. The number of layers of the multiple transition metal oxide films in the optical structure in which multiple transition metal oxide films and another optical film are alternately laminated is 2 or more, but may be 3 or more, 10 or more, 20 or more, 30 or more, or 40 or more. The more layers of the transition metal oxide film in the optical structure, the greater the effect of controlling the optical properties of the transition metal oxide film in the optical structure by the hydrogen content.

[0044] The film in contact with the transition metal oxide film may be an oxide film or a fluoride film, but is preferably an oxide film in consideration of adhesion to the transition metal oxide film. A structure in which the transition metal oxide film is disposed between a first oxide film and a second oxide film, with the lower surface of the transition metal oxide film in contact with the first oxide film and the upper surface of the transition metal oxide film in contact with the second oxide film, is preferable because the transition metal oxide film has high adhesion and stability. Examples of the oxide film in contact with the transition metal oxide film include oxide films of typical elements such as silicon oxide film, aluminum oxide film, magnesium oxide film, and zinc oxide film. In other words, in a structure in which oxide films of transition elements and oxide films of typical elements are alternately stacked, the properties of the oxide film of the transition element can be adjusted by the hydrogen content.

[0045] A film containing an amorphous transition metal oxide as a main component, with a hydrogen content of 1.0 at% or more, and with the sum of the transition metal content, oxygen content, hydrogen content, and argon content being greater than 99.0%, has few impurities and is therefore suitable not only as an optical film but also as an insulating film for electrical use.

[0046] The electric element may include a first portion that is an electrode, a second portion that is a semiconductor layer or an electrode, and an amorphous transition metal oxide film. In order to insulate the first portion that is an electrode from the second portion that is a semiconductor layer or an electrode, an amorphous transition metal oxide film may be disposed between the first portion that is an electrode and the second portion that is a semiconductor layer or an electrode. If the electric element is 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 electric element may be a capacitor with a MOS (Metal-Oxide-Semiconductor) structure or a capacitor with a MOM (Metal-Oxide-Metal) structure.

[0047] A reactive sputtering method is useful for forming a transition metal oxide film containing a large amount of hydrogen of 1.0 at% or more. A transition metal oxide film containing hydrogen can be formed by generating plasma in an atmosphere containing oxygen gas, hydrogen gas, and argon gas, sputtering a transition metal target with argon, and reacting the sputtered metal with oxygen and hydrogen. At this time, the crystallinity of the transition metal oxide film can be controlled by the amount of oxygen gas. For example, crystallization is more likely to occur when the amount of oxygen gas is increased, and it is more likely to become amorphous when the amount of oxygen gas is decreased. In addition, the crystallinity of the transition metal oxide film can also be controlled by the sputtering power during film formation, the pressure of the atmosphere, the temperature of the substrate, and the positional relationship between the target and the substrate. For example, film formation at a higher sputtering power or at a lower atmospheric pressure makes it easier to make the film amorphous. In addition, it is also easier to make the film amorphous by increasing the distance between the target and the substrate in the direction perpendicular to the substrate's film formation surface, or by shifting the target and the substrate in the direction parallel to the substrate's film formation surface. However, even if any of the above conditions favorable for amorphization are satisfied, crystallization may occur depending on the degree of other parameters, so appropriate condition setting is necessary for amorphization. The hydrogen content in the transition metal oxide film can be controlled by the amount of hydrogen gas. For example, the hydrogen content decreases when the amount of hydrogen gas is reduced, and increases when the amount of hydrogen gas is increased. Impurity A may originate from the gas in the film formation atmosphere, such as argon, and impurity B may originate from impurities in the target. Other impurities may be metal elements contained in the film formation device, or carbon, nitrogen, or fluorine that adheres to the sputtering target or is mixed into the film formation gas. By minimizing such impurities, a high-quality film can be obtained.

[0048] Hereinafter, embodiments using hafnium oxide as the transition metal oxide will be described as Embodiments 1 and 2. Hafnium oxide is characterized by a high refractive index and dielectric constant, and therefore applications in the fields of optical elements and semiconductor elements are being considered.

[0049] In the field of optical elements, attempts have been made to coat optical components such as lenses and filters with a film containing hafnium oxide as an optical film. As optical equipment is required to have high performance, the number of optical elements used in the equipment tends to increase, and the number of optical surfaces that need to be coated with an optical film also tends to increase. In addition, the optical film to be coated is not necessarily composed of a single layer, but may be composed of multiple layers, so the total number of layers to be provided tends to increase.

[0050] In this context, the optical surfaces of exposure equipment (semiconductor manufacturing equipment) that handles ultraviolet wavelengths such as i-lines and h-lines can be coated with hafnium oxide, a high refractive index material that is less susceptible to band gap absorption in the ultraviolet range. In the field of optical elements, there has been a demand for a high-performance optical film that contains hafnium oxide and achieves a good balance between a high refractive index and low light absorption.

[0051] In the field of semiconductor devices, there has been a demand for a high-performance gate insulating film that contains hafnium oxide and achieves a good balance between a high dielectric constant and a low leakage current. Therefore, one aspect of the first and second embodiments is to provide a technique that is advantageous in achieving high performance in a film containing hafnium oxide. One aspect of the first and second embodiments is a film containing amorphous hafnium oxide as a main component and having a hydrogen content of 1.0 at % or more.

[0052] According to the first and second embodiments, in a film containing hafnium oxide, a high refractive index and low absorption can be achieved in a well-balanced manner, and a high dielectric constant and low leakage current can be achieved in a well-balanced manner, thereby providing an advantageous technique for realizing high performance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hafnium oxide-containing film and an apparatus including the film, which are embodiments of the present invention, will be described with reference to the drawings.

[0053] [Embodiment 1] (Optical elements) FIG. 1 shows 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 is formed by alternately stacking 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. The optical structure 102 can also be called a multilayer film. Here, the alternate stacking of the first type layer and the second type layer 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 for the first type layer and the second type layer to be alternately stacked.

[0054] The substrate 101 can be made of materials such as calcium fluoride crystals, quartz glass, optical glass such as BK7 (borosilicate crown glass), resin, metal, etc. The substrate 101 can have various shapes, such as a flat shape or a shape having a curved surface, depending on the purpose and type of the optical element (for example, a lens, a mirror, a filter, a prism, etc.).

[0055] The material used as the main component of the high refractive index layer 102a is amorphous hafnium oxide (HfO2) containing hydrogen, which will be described in detail later. In the following description, a film mainly composed of hafnium oxide (HfO2) may be referred to as a hafnium oxide film. Note that the phrase "a film mainly composed of hafnium oxide" 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%), N (at%) of the elements other than hafnium and oxygen contained in the hafnium oxide film (J + K > L, J + K > M, J + K > N). In the hafnium oxide film, J + K is 100 at% or less. However, as will be described later, since the hafnium oxide film of the present embodiment contains elements other than hafnium and oxygen (for example, hydrogen), J + K is less than 100 at%. Typically, J < K < 3×J from the stoichiometric composition HfO2. The hafnium content J is, for example, 20 to 50 at%, and the oxygen content K is, for example, 50 to 80 at%. It is preferable that the sum of the hafnium content J (at%) and the oxygen content K (at%) in the hafnium oxide film is greater than the sum of the contents L (at%), M (at%), N (at%) of all the elements other than hafnium and oxygen contained in the hafnium oxide film (J + K > L + M + N). In this case, J + K will be greater than 50 at%. Here, all the elements other than hafnium and oxygen are exemplified in the case of three types, but all the elements other than hafnium and oxygen may be one type, two types, or four or more types.

[0056] Examples of the material used for the low refractive index layer 102b include, but are not limited to, materials mainly containing silicon oxide or aluminum oxide. For example, MgF2, CaF2, LaF3, CeF3, YF3, etc. may be used.

[0057] As shown in FIG. 1, the optical structure 102 has a structure in which high-refractive index layers 102a and low-refractive index layers 102b are alternately laminated in order from the substrate 101 side, with the low-refractive index layer 102b being the outermost layer. However, the structure may be changed depending on the application of the optical element. For example, the low-refractive index layers 102b and high-refractive index layers 102a may be alternately laminated in order from the substrate 101 side, with the low-refractive index layer 102b being the outermost layer. In addition, a protective layer may be provided on the outermost low-refractive index layer 102b to serve as the outermost layer, an intermediate-refractive index layer made of an intermediate-refractive index material may be sandwiched between the high-refractive index layer 102a and the low-refractive index layer 102b, or an adhesive layer may be provided between the substrate 101 and the optical structure 102. It is not essential that the optical structure 102 has an alternate laminate structure in which the low-refractive index layers 102b and the high-refractive index layers 102a are alternately laminated. It is not essential to have a multi-layer structure including the high refractive index layer 102a and the low refractive index layer 102b, and the film may have a single-layer structure including only the high refractive index layer 102a.

[0058] (Manufacturing method) A method for manufacturing an optical element (optical component) according to this embodiment having an amorphous hafnium oxide film (high refractive index layer) containing hydrogen will be described. Note that a known film forming method can be used to form the low refractive index layer 102b, so a description thereof will be omitted.

[0059] 2 is a schematic diagram of a sputtering film formation apparatus 200 used in the manufacture of an optical element. The sputtering film formation apparatus 200 has a vacuum chamber 201 as an airtight container and an exhaust system 202 for exhausting the inside of the vacuum chamber 201. In addition, an argon gas inlet port 204, an oxygen gas inlet port 205, and a hydrogen gas inlet port 206 are provided so that gases required for film formation can be introduced into the vacuum chamber 201. In addition, a sputtering target 210, a backing plate 211, a magnet mechanism 207, and a substrate holding mechanism 208 are provided in association with the vacuum chamber 201. The substrate 101 of the optical element is held by the substrate holding mechanism 208, and power is applied from a power source 203, whereby film formation can be performed by a reactive sputtering method.

[0060] To form an amorphous hafnium oxide film (high refractive index layer) containing hydrogen, deposition is performed by reactive sputtering in the following procedure. For example, a substrate 101 made of quartz glass processed into the shape of a predetermined optical element and, for example, an 8-inch piece of metallic hafnium (with a purity of 99.9 wt % or more) serving as a sputtering target 210 are set in a vacuum chamber 201. At this time, the distance between the substrate 101 and the sputtering target 210 is, for example, 125 mm. Then, an exhaust system 202 is used to raise the pressure to 5×10 -5 The vacuum chamber 201 is evacuated until a vacuum level of about Pa is reached. Then, plasma discharge is performed while introducing argon gas from the argon gas introduction port 204, oxygen gas from the oxygen gas introduction port 205, and hydrogen gas from the hydrogen gas introduction port 206. That is, a power supply 203 supplies 50 W / cm 2 to the sputtering target 210. 2 A plasma discharge is generated by applying a power of about 100 nm, and amorphous hafnium oxide containing hydrogen is formed on a substrate 101 having a diameter of 30 mm and a thickness of 1 mm, for example. The thickness of each layer is not necessarily limited to about 100 nm, and is appropriately set depending on the wavelength of light handled by 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, 10 to 1000 nm, for example, 10 to 100 nm. A hafnium oxide film having a thickness of 100 nm may be formed by stacking hafnium oxide layers having a thickness of 100 nm without any other layers therebetween. Specific examples and comparative examples will be described below.

[0061] [Examples 1 to 4], [Comparative Examples 1 to 2] The high refractive index layer used in the optical structure will be described with reference to Examples 1 to 4 and Comparative Examples 1 to 2. The high refractive index layers according to Examples 1 to 4 and Comparative Example 2 were formed while oxygen gas was introduced from the oxygen gas introduction port 205 at a flow rate of 20 sccm. The high refractive index layer according to Comparative Example 1 was formed while oxygen gas was introduced from the oxygen gas introduction port 205 at a flow rate of 60 sccm. In both Examples and Comparative Examples, argon gas was introduced from the argon gas introduction port 204 at a flow rate of 60 sccm to form the layer. In Example 1, plasma discharge was performed while hydrogen gas was introduced from the hydrogen gas introduction port 206 at a flow rate of 30 sccm. In other Examples and Comparative Examples, the flow rate of hydrogen gas was changed from that of Example 1 to adjust the amount of hydrogen contained in the film as described below. The above conditions are merely examples and can be changed depending on the structure of the film formation apparatus. In general, when the oxygen flow rate introduced into the chamber is increased, the film quality tends to move from amorphous to crystalline, and when the hydrogen flow rate is increased, the amount of hydrogen contained in the film tends to increase. It is presumed that when the flow rate of oxygen introduced is increased, more negative oxygen ions are generated in the chamber, and the energy input to the substrate increases, accelerating crystallization.

[0062] The hafnium oxide film (single film) of each of the examples and comparative examples was evaluated for crystallinity, hydrogen content, light absorptance, and refractive index.

[0063] The crystallinity was evaluated using X-ray diffraction analysis. In the following explanation, non-crystalline (or amorphous) refers to a state where no clear diffraction peak is detected when the film to be measured is irradiated with X-rays at a small incident angle of about 0.5 degrees and the diffraction pattern is observed, in other words, a halo pattern is observed. Therefore, the term "amorphous" does not necessarily exclude a state where a material in a microcrystalline state is contained. For example, FIG. 7 shows the X-ray diffraction pattern (incident angle 0.4 degrees) of the hafnium oxide film of Example 1, and since only a halo pattern is observed and no clear crystal peak is seen, it can be determined that the film quality of Example 1 is amorphous. Also, for example, FIG. 8 shows the X-ray diffraction pattern (incident angle 0.4 degrees) of the hafnium oxide film of Comparative Example 1, and since a clear peak due to crystals is observed, it can be determined that the film of Comparative Example 1 is crystalline. The crystallinity was evaluated for other Examples and Comparative Examples using the same criteria.

[0064] The hydrogen content in the film was evaluated by irradiating the hafnium oxide film with a high-energy ion beam, for example of the MeV order, and using the Elastic Recoil Detection Analysis (ERDA) method. Materials other than hydrogen in the film were evaluated by irradiating the film with a high-energy ion beam of the MeV order, and using the Rutherford backscattering spectrometry (RBS) method. Using these results, the hydrogen content in at% in the hafnium oxide film was calculated.

[0065] The optical absorptivity and refractive index were evaluated by measuring the transmittance and reflectance at a light incidence angle of 5 degrees using an ultraviolet-visible-near infrared spectrophotometer in the wavelength range of 200 nm to 500 nm.

[0066] The light absorptance was calculated according to the following formula. A(%)=100-T(%)-R(%) (Formula 1) Here, A (%) represents the light absorption rate, T (%) represents the transmittance, and R (%) represents the reflectance.

[0067] The refractive index was measured using the optical thin film analysis and design software FilmWizard from Scientific Computing International. TM The calculation was performed by analysis using

[0068] The optical absorptivity and refractive index were evaluated based on light with a wavelength of 280 nm as the standard in order to evaluate the suitability of the optical element for exposure equipment (semiconductor manufacturing equipment) that handles wavelengths in the ultraviolet region such as i-line and h-line. Of course, if the optical element is intended for a different purpose, it can be evaluated based on a wavelength suitable for that purpose. Wavelengths suitable for optical elements are not limited to those in the ultraviolet region, but may also be those in the visible light region or infrared region. The evaluation results for Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

[0069] [Table 1]

[0070] The hafnium oxide film of Example 1 was amorphous, and the hydrogen content in the hafnium oxide film was 6.5 at %. The hafnium oxide film of Example 1 had an optical absorptance of 0.08% at a wavelength of 280 nm and a refractive index of 2.253 at a wavelength of 280 nm.

[0071] The hafnium oxide film of Example 2 was amorphous, had a hydrogen content of 15.8 at%, and had an optical absorptance of 0.04% at a wavelength of 280 nm and a refractive index of 2.225 at a wavelength of 280 nm.

[0072] The hafnium oxide film of Example 3 was amorphous, had a hydrogen content of 1.0 at %, and had an optical absorptance of 0.77% at a wavelength of 280 nm and a refractive index of 2.260 at a wavelength of 280 nm.

[0073] In another example, which had film formation conditions between those of Example 1 and Example 3, the crystallinity of the hafnium oxide film was amorphous, the hydrogen content in the hafnium oxide was 3.8 at%, the optical absorptance at a wavelength of 280 nm was 0.61%, and the refractive index at a wavelength of 280 nm was 2.252.

[0074] The hafnium oxide film of Example 4 was amorphous, had a hydrogen content of 17.0 at %, and had an optical absorptance of 0.06% at a wavelength of 280 nm and a refractive index of 2.031 at a wavelength of 280 nm.

[0075] The hafnium oxide film of Comparative Example 1 was crystalline, had a hydrogen content of 0 at %, and had an optical absorptance of 3.43% at a wavelength of 280 nm and a refractive index of 2.171 at a wavelength of 280 nm.

[0076] The hafnium oxide film of Comparative Example 2 was amorphous, had a hydrogen content of 0 at%, and had an optical absorptance of 0.80% at a wavelength of 280 nm and a refractive index of 2.262 at a wavelength of 280 nm.

[0077] The hafnium oxide film of the Reference Example, in which the hydrogen flow rate was greater than that of Comparative Example 1, was crystalline and had a hydrogen content of 7.5 at %. The hafnium oxide film of the Reference Example had an optical absorptance of 0.53% at a wavelength of 280 nm and a refractive index of 2.205 at a wavelength of 280 nm.

[0078] When comparing Comparative Example 1 and Comparative Example 2, which are substantially free of hydrogen, Comparative Example 2, which is amorphous, has a higher refractive index and a lower optical absorptance than Comparative Example 1, which is crystalline. When comparing Example 1, which has a hydrogen content of 6 to 8 at%, and Reference Example, Example 1, which is amorphous, has a higher refractive index and a lower optical absorptance than Reference Example, which is crystalline. Examples 1 to 4, which have a higher hydrogen content than Comparative Example 2, which is amorphous, have a lower optical absorptance than Comparative Example 2. Reference Example, which has a higher hydrogen content than Comparative Example 1, which is crystalline, has a lower optical absorptance and a higher refractive index than Comparative Example 1. A first guideline for the optical absorptance is less than 1.0%, a more preferable second guideline is 0.5% or less, and a more preferable third guideline is 0.2% or less. A first guideline for the refractive index is 2.10 or more, a more preferable second guideline is 2.15 or more, and a more preferable third guideline is 2.20 or more. It can be seen from Example 4 that when the hydrogen content exceeds 17%, the refractive index drops to 2.031 even if the film is amorphous. Also, it can be seen from Comparative Example 1 that when the film is crystalline and contains substantially no hydrogen, the light absorptance increases to 3.43%.

[0079] Thus, the change in absorptivity and refractive index due to the hydrogen content can be greater in an amorphous film than in a crystalline film. Therefore, in an amorphous film, the absorptivity and refractive index can be significantly controlled by setting the hydrogen content to 1 at% or more. Note that a hydrogen content of 1 at% or more includes a hydrogen content of 1.0 at% as in Example 3, and also includes a hydrogen content of 1.0 at% or more.

[0080] From the above, it can be seen that as a high-performance optical film that well balances a high refractive index and low light absorption, an amorphous hafnium oxide film containing hydrogen in the range of 1 at% or more and 16 at% or less is suitable. Among them, an amorphous hafnium oxide film containing hydrogen in the range of 6.5 at% or more and 15.8 at% or less is particularly preferable because it can achieve both a high refractive index of 2.22 or more and an extremely low light absorption of less than 0.1% (0.08% or less). In the hafnium oxide film of the embodiment, it is not necessary to actively add silicon to the hafnium oxide film, and it is preferable that the silicon content O in the hafnium oxide film is smaller than the hydrogen content L (O < L). The silicon content O in the hafnium oxide film described in the above examples is less than 1 at%, 0.1 at% or less, and below the detection limit. In the case of a hafnium oxide film added with silicon, not only may the refractive index decrease due to the addition of silicon, but the light absorption is not necessarily sufficiently reduced. For example, in a hafnium oxide film added with 1 at% to 10 at% of silicon, it is possible to reduce the transmission loss per single film to 1% or less. However, for example, when coated on 40 surfaces, losses of 10% or more may occur cumulatively, and it is not necessarily sufficient as optical performance. In the hafnium oxide film of the embodiment, it is not necessary to actively add carbon to the hafnium oxide film, and it is preferable that the carbon content P in the hafnium oxide film is smaller than the hydrogen content L (P < L). The carbon content P in the hafnium oxide film described in the above examples is less than 1 at%, 0.1 at% or less, and below the detection limit. In the hafnium oxide film of the embodiment, it is not necessary to actively add nitrogen to the hafnium oxide film, and it is preferable that the nitrogen content Q in the hafnium oxide film is smaller than the hydrogen content L (Q < L). The nitrogen content Q in the hafnium oxide film described in the above examples is less than 1 at%, 0.1 at% or less, and below the detection limit.

[0081] In addition, in the hafnium oxide film of the embodiment, elements other than hafnium, oxygen, and hydrogen may be contained. For example, the hafnium oxide film described in the above examples may contain argon. This argon is due to the argon gas introduced from the argon gas introduction port 204 during film formation. It is preferable that the argon content M in the hafnium oxide film is smaller than the hydrogen content L (M < L). The argon content M in the hafnium oxide film is, for example, 0.5 to 5 at%. Further, the hafnium oxide film described in the above examples may contain zirconium. This zirconium is derived from the sputtering target 210 used during film formation. It is preferable that the zirconium content N is smaller than the hydrogen content L (N < L). The zirconium content N in the hafnium oxide film is, for example, 0.05 to 0.5 at%. It is also preferable that the zirconium content N is smaller than the argon content M (N < M). It is preferable that the silicon content O in the hafnium oxide film is smaller than the argon content M (O < M). It is preferable that the silicon content O in the hafnium oxide film is smaller than the zirconium content N (O < N). This embodiment can achieve a high refractive index and low light absorption while containing argon and zirconium. In the hafnium oxide films of Examples 1 to 4 and Comparative Examples 1 and 2 described above, elements other than hafnium, oxygen, hydrogen, argon, and zirconium are below the detection limit. The zirconium content N in Examples 1 to 4 is within the range of 0.2 to 0.3 at%. Therefore, the sum (J + K + L + M) of the hafnium content J, the oxygen content K, the hydrogen content L, and the argon content M is within the range of 99.7 to 99.8 at%. In Examples 1 to 4, the hafnium content J is within the range of 25 to 33 at%, the oxygen content K is within the range of 50 to 66 at%, and the argon content M is within the range of 1 to 2 at%. The ratio (K / M) of the oxygen content K to the hafnium content M is greater than 2.00 and smaller 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).

[0082] For reference, a graph showing the optical absorptance versus hydrogen content is shown in Fig. 3, and a graph showing the refractive index versus hydrogen content is shown in Fig. 4. In addition, Fig. 5 shows the wavelength dependence of optical absorption in Examples 1 and 3, and Fig. 6 shows the wavelength dependence of refractive index in Examples 1 and 4.

[0083] From FIG. 3, it is estimated that the absorptance when the hydrogen content in the amorphous hafnium oxide is 5 at% or more can be reduced to less than half of the absorptance when the hydrogen content is 0 at%. As shown in FIG. 3, when the hydrogen content in the amorphous hafnium oxide is 6 at% or more, the absorptance is sufficiently low at 0.1% or less. As shown in FIG. 5, the absorptance is significantly reduced in the wavelength range of 400 nm or less in Example 1. Moreover, as shown in FIG. 4, a high refractive index can be maintained in the range of the hydrogen content of 16 at% or less. The inventors have speculated on a model in which hydrogen fills oxygen defects generated in hafnium oxide containing hydrogen. Assuming that hafnium oxide with a hydrogen content of 0 at% is HfO2, which is a stoichiometric composition, hafnium oxide containing hydrogen is HfO 2-X H X The hydrogen concentration calculated by simulation using this model is 1×10 if the hydrogen content is 1 at%. 21 atoms / cm 3 If the hydrogen content is 5 at%, it is 5 × 10 21 atoms / cm 3 If the hydrogen content is 6 at%, the 21 atoms / cm 3 If the hydrogen content is 10 at%, it is about 1 × 10 22 atoms / cm 3 If the hydrogen content is 16 at%, it is 1.6 × 10 22 atoms / cm 3 If the hydrogen content is 20 at%, it is about 2 × 10 22 atoms / cm 3 The hydrogen concentration of the hafnium oxide film of this embodiment is about 1×10 21 atoms / cm 3 Greater than or equal to 2×1022 atoms / cm 3 It can be in the following range: atoms / cm 3 It is desirable to satisfy an appropriate hydrogen content (at%) within this hydrogen concentration range shown in FIG. 1. Furthermore, the hydrogen concentration of the hafnium oxide film of this embodiment is 5×10 21 atoms / cm 3 It can be more than 6×10 21 atoms / cm 3 It can be more than 1.6×10 22 atoms / cm 3 However, depending on the amount of impurities such as argon and zirconium and the packing density of the hafnium oxide film, the hydrogen concentration can be as high as 1×10 21 atoms / cm 3 The hydrogen content may be in the range of 1 to 16 at% or 6 to 16 at% or less, or the hydrogen concentration may be less than 1×10 21 atoms / cm 3 The hydrogen content may be in the range of 1 to 16 at% or 6 to 16 at%. 22 atoms / cm 3 The hydrogen content may be in the range of 1 to 16 at % or 6 to 16 at %.

[0084] The reason why the light absorption rate improved by adding hydrogen to hafnium oxide is speculated to be because the lattice defects, which are the main cause of the deterioration of light absorption, were repaired by hydrogen. In addition, the reason why the refractive index dropped sharply when the hydrogen content exceeded 16 at% is unclear, but it is speculated that this is because hydrogen penetrated not only into the lattice defects of hafnium oxide but also into the lattices, deteriorating the packing of hafnium oxide. Furthermore, the reason why the light absorption of crystallized hafnium oxide does not improve completely even when hydrogen is added is speculated to be because a crystal-derived level is formed in the band gap, which causes new light absorption.

[0085] [Example 5], [Example 6] A specific example of an optical structure (anti-reflection structure) formed on the surface of a transmissive optical element will be described. As Example 5, an optical structure (anti-reflection structure) was formed by alternately stacking an amorphous hafnium oxide film (high refractive index layer) containing 6.5 at % hydrogen and a low refractive index film, as described in Example 1. As Example 6, an optical structure (anti-reflection structure) was formed by alternately stacking an amorphous hafnium oxide film (high refractive index layer) containing 17.0 at % hydrogen and a low refractive index film, as described in Example 4.

[0086] FIG. 9 is a cross-sectional view showing the layer configuration of Example 5 and Example 6. In the optical element 900, a total of four high-refractive index layers 902a made of a high-refractive index material and low-refractive index layers 902b made of a low-refractive index material are alternately stacked on a quartz substrate 901, which is a base, to form an optical structure 902. The low-refractive index layers 902b are formed using silicon oxide. In consideration of the intended use of the optical element 900, in order to maximize the anti-reflection properties in the wavelength range of 280 nm to 400 nm, the physical film thickness of each layer was optimized based on the refractive index values ​​at a wavelength of 280 nm in Examples 1 and 4 to determine the configuration of the optical structure. The specifications of each layer in Example 5 are shown in Table 2.

[0087] [Table 2] The specifications of each layer in Example 6 are shown in Table 3.

[0088] [Table 3]

[0089] FIG. 10 shows the reflectance characteristics of the optical structures (antireflection structures) of Examples 5 and 6. In the wavelength range of 280 nm to 400 nm, Example 5, which uses an amorphous film with a high refractive index containing 6.5 at % hydrogen, can obtain a lower reflectance than Example 6, which uses an amorphous film with a hydrogen content of 17.0 at %. The average reflectance in this wavelength range is 0.10% in Example 5 and 0.33% in Example 6. In addition, in the case of Example 5, the reflectance is 0.25% or less at any wavelength in the wavelength range of 290 nm to 385 nm, and very good antireflection characteristics can be obtained.

[0090] [Example 7], [Example 8] A specific example of an optical structure (reflection structure) formed on the surface of a reflective optical element will be described. As Example 7, an optical structure (reflection structure) was formed by alternately stacking an amorphous hafnium oxide film (high refractive index layer) containing 6.5 at % hydrogen and a low refractive index layer, as described in Example 1. As Example 8, an optical structure (reflection structure) was formed by alternately stacking an amorphous hafnium oxide film (high refractive index layer) containing 17.0 at % hydrogen and a low refractive index layer, as described in Example 4.

[0091] FIG. 11 is a cross-sectional view showing the layer configurations of Examples 7 and 8, but the layer configurations are different from those of the antireflection structures of Examples 5 and 6. That is, a total of five low-refractive index layers 1002b made of a low-refractive index material and high-refractive index layers 1002a made of a high-refractive index material are alternately stacked on a substrate 1001 of a reflective optical element 1000 to form an optical structure 1002. The substrate 1001 in this example is made of aluminum, and is an aluminum film with a thickness of about 100 nm coated on a glass plate, but the aluminum of the substrate 1001 may be an aluminum plate. The low-refractive index layer 1002b is formed using silicon oxide. In consideration of the intended use of the optical element 1000, in order to maximize the reflectance in the wavelength range of 280 nm to 400 nm, the physical film thickness of each layer was optimized based on the refractive index values ​​at a wavelength of 280 nm in Examples 1 and 4 to determine the configuration of the optical structure.

[0092] The specifications of each layer in Example 7 are shown in Table 4. [Table 4]

[0093] The specifications of each layer in Example 8 are shown in Table 5. [Table 5]

[0094] FIG. 12 shows the reflectance characteristics of the optical structures (reflection structures) of Examples 7 and 8. In the wavelength range of 280 nm to 400 nm, Example 7, which uses an amorphous film with a high refractive index and containing 6.5 at % hydrogen, can obtain a higher reflectance than Example 8, which uses an amorphous film with a hydrogen content of 17.0 at %. The average reflectance in this wavelength range was 93.9% for Example 7 and 91.8% for Example 8. In addition, in the case of Example 7, the reflectance is 93% or more at all wavelengths from 290 nm to 380 nm, and very good reflectance characteristics can be obtained.

[0095] [Example 9], [Example 10] A specific example in which at least one lens of a lens group provided in an exposure device (semiconductor manufacturing device) is coated with an optical structure (anti-reflection structure) is described. As Example 9, a lens group was created in which both sides (total 40 surfaces) of 20 lenses provided in the exposure device were coated with the optical structure (anti-reflection structure) described in Example 5. That is, an optical structure (anti-reflection structure) in which an amorphous hafnium oxide film (high refractive index layer) containing 6.5 at % hydrogen and a low refractive index layer were alternately laminated was formed on the surface of each lens. Also, as Example 10, a lens group was created in which both sides (total 40 surfaces) of 20 lenses were coated with the optical structure (anti-reflection structure) described in Example 6. That is, an optical structure (anti-reflection structure) in which an amorphous hafnium oxide film (high refractive index layer) containing 17.0 at % hydrogen and a low refractive index layer were alternately laminated was formed on the surface of each lens.

[0096] For Example 9 and Example 10, in order to evaluate the suitability as a lens for an exposure tool equipped with an ultraviolet light source, the transmission loss was measured using 280 nm ultraviolet light. The results are shown in Table 6. In a lens for an exposure tool equipped with an ultraviolet light source, the ultraviolet light generated by the ultraviolet light source is irradiated onto the hafnium oxide film of the lens, so the ultraviolet light was irradiated onto the hafnium oxide film in the same manner. Even if the lens has an infrared or visible light source, the suitability as an optical element can be evaluated in the same manner using the light irradiated onto the hafnium oxide film.

[0097] [Table 6]

[0098] In the lens group of Example 9, each surface can achieve both low light absorption and low reflectance, and the transmission loss can be extremely small, so that the transmission loss can be suppressed to 10% or less even at lens surface 40. On the other hand, in Example 10, the reflectance is significantly increased compared to Example 9, so the transmission loss at lens surface 40 reaches 10% or more. The reason why the reflectance of Example 10 is worse than that of Example 9 is thought to be due to the low refractive index of the hafnium oxide layer.

[0099] The lens group of the ninth embodiment has an effect of increasing the exposure intensity of an exposure apparatus by using it, for example, as an illumination lens group or a projection lens group of an exposure apparatus. Therefore, the exposure time can be shortened, and the processing capacity of the exposure apparatus can be improved.

[0100] [Embodiment 2] In the second embodiment, an amorphous hafnium oxide film containing hydrogen in the range of 1 at % or more and 16 at % or less is used in a semiconductor element.

[0101] In Examples 11 and 12, the above-mentioned hafnium oxide film is used as the gate insulating film (high-k gate insulating film) of a transistor. The hafnium oxide film as a high dielectric constant material film can be formed in the same manner as in the first embodiment using the same apparatus, but the film thickness is set to a thickness suitable for a gate insulating film. Regarding the relationship between the refractive index and the dielectric constant, electronic polarization and ionic polarization can be distinguished from each other, and the dielectric constant can be a value that takes both electronic polarization and ionic polarization into consideration. The dielectric constant that can be calculated from the refractive index is the dielectric constant as electronic polarization, and the dielectric constant ε, which is a factor of electronic polarization, is correlated with the refractive index n (ε 2 =n). A high refractive index can mean a high dielectric constant due to electronic polarization. Hafnium oxide is an ionic bonding material, so when used in an electric field environment, ionic polarization occurs in addition to electronic polarization. When using hafnium oxide as a gate insulating film, it is necessary to evaluate the dielectric constant taking into account the polarization of both. However, if the hydrogen content of hafnium oxide is set to 1 to 16 at%, it is possible to at least suppress the decrease in dielectric constant due to electronic polarization. In addition, when silicon is diffused into a hafnium oxide film to form a silicon-containing film, even if the rate at which crystallization occurs can be reduced, the inclusion of silicon may result in a decrease in dielectric constant. In the thirteenth embodiment, the above-mentioned hafnium oxide film can be provided as an anti-reflection structure on the light receiving surface side of the image sensor.

[0102] [Example 11] FIG. 13 is a schematic cross-sectional view for explaining an embodiment of a semiconductor device having a MOS transistor. The semiconductor device 130 includes an n-channel MOSFET 131a and a p-channel MOSFET 131b formed on a semiconductor layer 133 such as n-type single crystal silicon. The n-channel MOSFET 131a and the p-channel MOSFET 131b form a complementary circuit (CMOS circuit). An amorphous hafnium oxide film containing hydrogen in the range of 1 at% or more and 16 at% or less 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 to 10 nm. Since the gate insulating films 132a and 132b are amorphous and contain a predetermined amount of hydrogen, they have very few crystal grain boundaries and can achieve a high dielectric constant. Therefore, the MOS transistor of this embodiment having the gate insulating film 132a and the gate insulating film 132b can significantly reduce the leakage current.

[0103] The application of the amorphous hafnium oxide film containing hydrogen in the range of 1 at % or more and 16 at % or less to the gate insulating film of a MOSFET is not limited to the example of Fig. 13. For example, it may be used as the gate insulating film of a MOS transistor formed on a semiconductor layer such as p-type single crystal silicon, or it may be used as the gate insulating film of a single n-channel MOSFET or p-channel MOSFET instead of a complementary type, and it is possible to significantly reduce the leakage current.

[0104] [Example 12] FIG. 14 is a schematic cross-sectional view for explaining an example of a semiconductor element having a thin film transistor. A semiconductor element 140 has a thin film transistor formed on a glass substrate 141. The thin film transistor has a semiconductor layer 143 such as low-temperature polysilicon, 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 hydrogen in the range of 1 at % or more and 16 at % or less is used for the gate insulating film 142. The thickness of the gate insulating film 142 of the thin film transistor is typically 50 to 500 nm. Since it is amorphous and contains a predetermined amount of hydrogen, it has very few crystal grain boundaries and can achieve a high dielectric constant, so that the thin film transistor of this embodiment having the gate insulating film 142 can significantly reduce the leak current. A liquid crystal display or an organic EL display is a semiconductor element having a thin film transistor. The high dielectric constant film according to the second embodiment can be used as the gate insulating film of the thin film transistor of the liquid crystal display or the organic EL display.

[0105] The application of an amorphous hafnium oxide film containing hydrogen in the range of 1 at% or more and 16 at% or less to the gate insulating film of a thin film transistor is not limited to the example of FIG. 14. For example, the semiconductor layer constituting the channel portion is not limited to a low-temperature polysilicon layer, but may 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. Even in such a case, it is possible to significantly reduce the leakage current in a thin film transistor having such a gate insulating film.

[0106] [Example 13] The substrate on which the optical structure of the first embodiment is provided may have an electro-optical structure. The electro-optical structure refers to a structure that converts an electrical signal into an optical signal or converts an optical signal into an electrical signal. FIG. 15 is a schematic partial cross-sectional view for explaining an example related to a back-illuminated imaging element. An imaging element is a type of optical element because it handles light, and is also a type of semiconductor element because it has a photodiode and a transistor. In the back-illuminated imaging element 150, a photodiode PD corresponding to each pixel is formed in a semiconductor substrate 151. The semiconductor substrate 151 functions as a substrate having an electro-optical structure for converting an optical signal into an electrical signal, which is realized by the photodiode. The photodiode PD includes a pn junction formed by an n-type region 152 extending in the thickness direction of the semiconductor substrate 151 and a p-type region 153 in contact with the n-type region 152 on both the front and back sides of the substrate. The photodiode PD of each pixel is partitioned by a p-type element isolation region 154. A p-type semiconductor well region 155 in contact with an element isolation region 154 is formed on the front side (lower side in the figure) of the semiconductor substrate 151, and a pixel transistor corresponding to each pixel is provided therein. The pixel transistor is formed by a source region, a drain region, a gate insulating film, and a gate electrode 156. Furthermore, a multilayer wiring 158 is provided on the front side via an interlayer insulating film 157.

[0107] On the other hand, an antireflection structure 160 having electrical insulation and antireflection functions is formed on the back side (upper side in the figure) of the semiconductor substrate 151, which is the light receiving side. The antireflection structure 160 has a two-layer structure, in which a silicon oxide film 161 and a hafnium oxide film 162 are laminated in this order from the semiconductor substrate 151 side. As in Example 5, a film having a refractive index of 1.506 is preferably used for the silicon oxide film 161. As in Example 5, a hafnium oxide film that is amorphous and has a hydrogen content of 6.5 at % and a refractive index of 2.253 is preferably used for the hafnium oxide film 162.

[0108] A light-shielding film 163 made of, for example, aluminum is disposed on the anti-reflection structure 160 in order to prevent crosstalk of incident light between pixels, and a planarization film 164 made of resin is further provided to provide a flat upper surface. On the planarization film 164, for example, an on-chip color filter 165 in a Bayer array and an on-chip microlens 166 are formed. The light-shielding film 163 is made of a metal such as aluminum or tungsten, and can also function as an electrode to which a fixed potential is applied. The anti-reflection structure 160 also functions as an insulating film that insulates the light-shielding film 163 from the semiconductor substrate 151 (semiconductor layer).

[0109] In this embodiment, by providing an amorphous hafnium oxide film containing hydrogen in the range of 1 at % or more and 16 at % or less on a photodiode, it is possible to realize high anti-reflection performance and low light absorption, and thus to realize a highly sensitive imaging element.

[0110] The imaging element to which the amorphous hafnium oxide film containing hydrogen in the range of 1 at% or more and 16 at% or less is applied is not limited to the example of FIG. 15, and the film can be suitably used as an anti-reflection structure in imaging elements other than back-illuminated type, for example, front-illuminated type imaging elements. In front-illuminated type imaging elements, the amorphous hafnium oxide film may serve as both an anti-reflection film and a gate insulating film. For example, the amorphous hafnium oxide film can be used as a gate insulating film of a transistor of a pixel circuit, and the amorphous hafnium oxide film can be extended to above a photodiode to be used as an anti-reflection film.

[0111] Moreover, by using the imaging element having such an anti-reflection structure, various cameras including interchangeable lens cameras and integrated lens cameras, smartphones, and in-vehicle camera modules can be configured. In the camera module, in addition to the lens and imaging element, a holding part (frame) that holds a plurality of optical components including the lens and the imaging element can be provided. Of course, the lens of the camera module may be coated with a hafnium oxide film. Also, the optical element having a base having an electro-optical structure may be a liquid crystal display or an organic EL display. In electronic devices such as cameras and smartphones, in addition to the optical element having a base having an electro-optical structure, a controller for electrically controlling the electro-optical structure can be provided. Also, if the optical element is an imaging element, the electronic device may be provided with a processor that processes a signal output from the imaging element. Also, if the optical element is a display element, the electronic device may be provided with a processor that processes a signal input to the display element. The electronic device to which the present embodiment can be applied may be an information device such as a smartphone or a personal computer. Alternatively, the electronic device may be office equipment such as a printer or a copier, medical equipment such as an X-ray device or an endoscope, industrial equipment such as a robot or a semiconductor manufacturing device, or transportation equipment such as a vehicle, an airplane, or a ship.

[0112] [Modifications of the first and second embodiments] The present invention is not limited to the above-described embodiments and examples, and many modifications are possible within the technical concept of the present invention.

[0113] The high refractive index film according to the first embodiment is widely applicable to coating optical elements including lenses, filters, mirrors, prisms, imaging elements (imaging devices) such as image sensors, and display elements (display devices) such as displays. Furthermore, it can be used in optical equipment such as exposure equipment, various cameras, and interchangeable lenses that are equipped with optical elements. These optical equipment may be equipped with a holding part (lens barrel) that holds the multiple optical components in addition to multiple optical components including an optical element coated with a hafnium oxide film. By laminating the high refractive index film according to the first embodiment and a low refractive index film having a smaller refractive index than that, a high-performance antireflection structure or reflection structure can be formed. For example, in an exposure equipment equipped with an ultraviolet light source, the exposure performance of the exposure equipment using ultraviolet light can be improved by providing the antireflection structure of the first embodiment on the lens and / or providing the reflection structure of the first embodiment on the mirror.

[0114] The high dielectric constant film according to the second embodiment is widely applicable as a gate insulating film for various transistors, and can be implemented in various semiconductor elements (semiconductor devices) including memories, processors, and logic ICs, and various electronic devices including smartphones and personal computers. The electronic devices to which the present embodiment can be applied may be information devices such as smartphones and personal computers, and communication devices such as modems and routers. Alternatively, the electronic devices may be office equipment such as printers and copiers, medical equipment such as X-ray equipment and endoscopes, industrial equipment such as robots and semiconductor manufacturing equipment, and transportation equipment such as vehicles, airplanes, and ships.

[0115] Hereinafter, as the third and fourth embodiments, embodiments using tantalum oxide as the transition metal oxide will be described. Tantalum oxide is characterized by a high refractive index and dielectric constant, and therefore applications in the fields of optical elements and electrical elements are being considered. In various optical devices including exposure devices, optical elements are coated with an optical film in order to improve optical characteristics such as anti-reflection characteristics or reflection characteristics. In capacitive elements and semiconductor elements, insulating films are used to insulate capacitive electrodes and gate electrodes from others.

[0116] In the field of optical elements, there has been a demand for optical films that achieve a good balance between a high refractive index and low light absorption and have high performance. In the field of electrical devices, there has been a demand for insulating films that achieve a good balance between high dielectric constant and low leakage current and have high performance.

[0117] Therefore, the present embodiment aims to provide a technique that is advantageous for realizing high performance in a film containing tantalum oxide. One aspect of the third and fourth embodiments is a film containing amorphous tantalum oxide as a main component and having a hydrogen content of 1.0 at% or more.

[0118] According to this embodiment, it is possible to provide a technique that is advantageous in realizing high performance by achieving a good balance between a high refractive index and low absorption, or a good balance between a high dielectric constant and low leakage current.

[0119] With reference to the drawings, a tantalum oxide film containing hydrogen in a predetermined range and an optical device including the film will be described as an embodiment of the present invention. Note that, although the terms "film" and "layer" are used in this specification, these are terms commonly used in the technical field without being strictly distinguished, and there is no intention to strictly distinguish between the two in this specification.

[0120] [Embodiment 3] FIG. 16 shows 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 can be called a multilayer film in which 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 laminated. Here, the alternate lamination of the first type layer and the second type layer 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, the optical element 100 includes at least four layers including the first type layers and the second type layers.

[0121] The substrate 101 can be made of materials such as calcium fluoride crystals, quartz glass, optical glass such as BK7 (borosilicate crown glass), resin, metal, etc. The substrate 101 can have various shapes, such as a flat shape or a shape having a curved surface, depending on the purpose and type of the optical element (for example, a lens, a mirror, a filter, a prism, etc.).

[0122] The material used as the main component of the high refractive index layer 102a is tantalum oxide (Ta2O5). As will be described later, the tantalum oxide (Ta2O5) of this embodiment contains hydrogen in an amount within a predetermined range. In the following description, a film mainly composed of tantalum oxide (Ta2O5) may be referred to as a tantalum oxide film. In this embodiment, the tantalum oxide film is an optical film and constitutes the optical structure 102. Tantalum oxide is a metal oxide whose metal component is tantalum. Let the content of the metal component (tantalum) in the film mainly composed of the metal oxide be J (at%) and the content of oxygen be K (at%). Here, a film mainly composed of tantalum oxide means that, for example, when the film contains two types of elements other than tantalum oxide, the content (atomic percentage) 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 content L (at%), M (at%) of each element other than (tantalum and oxygen) (J + K > L, J + K > M). Since the tantalum oxide film of this embodiment essentially contains hydrogen in an amount within a predetermined range, J + K is less than 100 at%. From the stoichiometric composition Ta2O5, typically 2×J < K < 3×J. The tantalum content J is, for example, 15 to 35 at%, typically 20 to 30 at%, and the oxygen content K is, for example, 50 to 75 at%, typically 60 to 70 at%. It is preferable that the sum of the tantalum content J (at%) and the oxygen content K (at%) in the tantalum oxide film is greater than the sum of the contents L (at%), 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 will be greater than 50 at%. In the above description, the case where there are two types of elements contained in the film other than (tantalum and oxygen) is exemplified, but it is not limited to two types and may be one type. In the tantalum oxide film of this embodiment, in the former case, the two types of elements are hydrogen and argon, and in the latter case, the one type of element is hydrogen.

[0123] In the film mainly composed of tantalum oxide of this embodiment, the element that is essential to be contained other than tantalum and oxygen is hydrogen, and the element that can be optionally contained is argon. The content of argon may be, for example, 0.5 at% or more, 5.0 at% or less, 3.0 at% or less, or 2.0 at% or less, and may be contained within a range of, for example, 0.9 at% or more and 1.6 at% or less. When the tantalum oxide film of this embodiment was analyzed, elements other than tantalum, oxygen, hydrogen, and argon were below the detection limit. Therefore, it can be said that the film mainly composed of tantalum oxide of this embodiment typically does not substantially contain elements other than these four kinds. Elements other than these four kinds that the tantalum oxide film may contain are, for example, boron (B), carbon (C), nitrogen (N), fluorine (F), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), and chlorine (Cl) as typical elements. Elements other than these four that may be contained in the tantalum oxide film include, for example, transition elements such as iron (Fe), nickel (Ni), chromium (Cr), niobium (Nb), and tungsten (W). In the film of this embodiment, if the content of each of the elements other than these four is less than 0.5 at%, and furthermore, 0.1 at% or less, the light absorption caused by elements other than these four can be sufficiently suppressed. When the content of elements other than these four is below the detection limit, the content of each of the elements other than these four can be 0 at%.

[0124] The low refractive index layer 102b may be made of, but is not limited to, a material containing silicon oxide or aluminum oxide as a main component. For example, MgF2, CaF2, LaF3, CeF3, YF3, etc. may also be used.

[0125] As shown in FIG. 16, the optical structure 102 has a structure in which high-refractive index layers 102a and low-refractive index layers 102b are alternately laminated in order from the base 101 side, with the low-refractive index layer 102b being the outermost layer. However, the structure may be changed depending on the application of the optical element. For example, the low-refractive index layers 102b and high-refractive index layers 102a may be alternately laminated in order from the base 101 side, with the low-refractive index layer 102b being the outermost layer. In addition, a protective layer may be provided on the outermost low-refractive index layer 102b to serve as the outermost layer, or an intermediate-refractive index layer made of an intermediate refractive index material may be sandwiched between the high-refractive index layer 102a and the low-refractive index layer 102b. Alternatively, a base layer such as an adhesive layer may be provided between the optical structure 102 and the base 101. Note that the optical structure 102 of the embodiment does not necessarily have an alternately laminated structure in which the low-refractive index layers 102b and the high-refractive index layers 102a are alternately laminated as shown in the figure. It is not essential to have a multi-layer structure including the high refractive index layer 102a and the low refractive index layer 102b, and the film may have a single-layer structure including only the high refractive index layer 102a.

[0126] A method for manufacturing the optical element of this embodiment having a tantalum oxide film (high refractive index layer) containing hydrogen in a predetermined range will be described. Note that a known film formation method can be used to form the low refractive index layer 102b, so a description thereof will be omitted.

[0127] 17 is a schematic diagram of a sputtering film formation apparatus 200 used in the manufacture of an optical element. The sputtering film formation apparatus 200 has a vacuum chamber 201 as an airtight container and an exhaust system 202 for exhausting the inside of the vacuum chamber 201. In addition, an argon gas inlet port 204, an oxygen gas inlet port 205, and a hydrogen gas inlet port 206 are provided so that gases required for film formation can be introduced into the vacuum chamber 201. In addition, a sputtering target 210, a backing plate 211, a magnet mechanism 207, and a substrate holding mechanism 208 are provided in association with the vacuum chamber 201. The substrate 101 of the optical element is held by the substrate holding mechanism 208, and power is applied from a power source 203, whereby film formation can be performed by a reactive sputtering method.

[0128] To form a tantalum oxide film (high refractive index layer) containing hydrogen, a film is formed by reactive sputtering in the following procedure. For example, a substrate 101 made of quartz glass processed into a shape of a predetermined optical element and, for example, a 9-inch metal tantalum (with a purity of 99.9 wt% or more) as a sputtering target 210 are set in a vacuum chamber 201. At this time, the distance between the substrate 101 and the sputtering target 210 is, for example, 200 mm. Then, the inside of the vacuum chamber 201 is evacuated using an exhaust system 202 until the pressure reaches a vacuum level of about 5×10-5 Pa. Then, plasma discharge is performed while introducing argon gas from an argon gas introduction port 204, oxygen gas from an oxygen gas introduction port 205, and hydrogen gas from a hydrogen gas introduction port 206. That is, a power of 10 W / cm2 is applied from the power source 203 to the sputtering target 210 to generate plasma discharge, and a hydrogen-containing tantalum oxide film is formed to a thickness of about 100 nm on a substrate 101 having a diameter of 30 mm and a thickness of 1 mm, for example. The amount of hydrogen contained in the film is adjusted by changing the flow rate of hydrogen gas. The thickness of each layer is not necessarily limited to about 100 nm, but is appropriately set depending on the wavelength of light handled by the optical element and the number of layers constituting the optical structure. The physical film thickness of the tantalum oxide film in the optical element is, for example, 8 to 1000 nm, and preferably 8 to 100 nm. A tantalum oxide film having a thickness of 100 nm may be formed by stacking tantalum oxide layers having a thickness of 100 nm without any other layers therebetween. Specific examples and comparative examples will be described below.

[0129] [Examples 1 to 5], [Comparative Examples 1 to 2] First, the high refractive index layer used in the optical structure will be described with reference to Examples 1 to 5 and Comparative Examples 1 to 2. In the examples and comparative examples, all high refractive index layers were formed while oxygen gas was introduced from the oxygen gas introduction port 205 at a flow rate of 200 sccm. In each of the examples and comparative examples, argon gas was introduced from the argon gas introduction port 204 at a flow rate of 200 sccm to form the layer. In addition, in Example 1, plasma discharge was performed while hydrogen gas was introduced from the hydrogen gas introduction port 206 at a flow rate of 20 sccm. In other examples and comparative examples, the flow rate of hydrogen gas was changed from that in Example 1 to adjust the amount of hydrogen contained in the layer as described below. In each of the examples and comparative examples, the layer was formed so that the layer had a thickness of about 100 nm. The above-mentioned film formation conditions are merely examples, and can be appropriately changed depending on the structure of the film formation device.

[0130] The tantalum oxide film (single film) of each of the examples and comparative examples was evaluated for hydrogen content, light absorptance, refractive index, and crystallinity.

[0131] The hydrogen content in the film was evaluated by irradiating the tantalum oxide film with a high-energy ion beam, for example of the MeV order, and using the Hydrogen Forward Scattering Spectrometry (HFS) method. Materials other than hydrogen in the film were evaluated by irradiating the film with a high-energy ion beam of the MeV order, and using the Rutherford backscattering spectrometry (RBS) method. Using these results, the contents of hydrogen, tantalum, oxygen, and argon in the tantalum oxide film were calculated in atomic percentage (at%). The measurement accuracy of the hydrogen content is ±0.1% in the very small range of 1% or less, and ±0.4% in the range of 3% or more.

[0132] Regarding the optical absorptance and refractive index, the transmittance and reflectance were measured using an ultraviolet-visible-near infrared spectrophotometer in the wavelength range of 200 nm to 500 nm at a light incidence angle of 5 degrees.

[0133] The light absorptance was calculated according to the following formula. A(%)=100-T(%)-R(%) (Formula 1) Here, A (%) represents the light absorption rate, T (%) represents the transmittance, and R (%) represents the reflectance.

[0134] The refractive index was calculated by analyzing the measured reflectance using FilmWizard (registered trademark), which is optical thin film analysis and design software manufactured by Scientific Computing International.

[0135] The crystallinity was evaluated using X-ray diffraction analysis. In the following explanation, non-crystalline (or amorphous) means that when the film to be measured is irradiated with X-rays at a small incident angle of about 0.5 degrees and the diffraction pattern is observed, no clear diffraction peak is detected, in other words, a halo pattern is observed. Therefore, the term "amorphous" here does not necessarily exclude a state in which microcrystalline material is contained.

[0136] FIG. 27 illustrates an X-ray diffraction pattern (incident angle 0.4 degrees) of the high refractive index layer (tantalum oxide film containing hydrogen in a predetermined range) of this embodiment. As shown in the figure, only a halo pattern is observed, and no clear crystal peak is observed, so that the high refractive index layer of this embodiment can be determined to be an amorphous film. All tantalum oxide films containing hydrogen in the range of 1.0 at% or more and less than 10.0 at% were amorphous, including the tantalum oxide film illustrated as an example. Note that, in crystalline (single crystal or polycrystal) tantalum oxide films, no advantage was found in making the hydrogen content 1.0 at% or more compared to the case where the hydrogen content is on the ppm order. In addition, under film formation conditions that can contain hydrogen at a content of 10.0 at% or more, a film that is easy to analyze could not be obtained.

[0137] Tables 7 and 8 show the evaluation results for Examples 1 to 5 and Comparative Examples 1 to 2. Table 7 summarizes the hydrogen content in each film, the refractive index for light with a wavelength of 313 nm, the optical absorptance at a wavelength of 313 nm, and the average optical absorptance in the wavelength ranges of 290 nm to 310 nm and 350 nm to 500 nm. Table 8 summarizes the contents (atomic percentages) of various elements contained in each film. Note that in Table 8, the total content shown in each example does not equal 100 at%, but this is because each content is rounded off to two decimal places, and the total becomes 100 at% when the number after the second decimal place is taken into account.

[0138] [Table 7]

[0139] [Table 8]

[0140] The crystallinity of the tantalum oxide film of Example 1 was amorphous, and the hydrogen content was 1.0 at%. The tantalum oxide film of Example 1 had a light absorptance of 0.40% at a wavelength of 313 nm, and a refractive index of 2.48. The average light absorptance in the wavelength range of 290 nm to 310 nm was 2.50%, and the average light absorptance in the wavelength range of 350 nm to 500 nm was 0.00%.

[0141] The crystallinity of the tantalum oxide film of Example 2 was amorphous, and the hydrogen content was 3.0 at%. The optical absorptance of the tantalum oxide film of Example 2 at a wavelength of 313 nm was 0.30%, and the refractive index was 2.46. The average optical absorptance in the wavelength range of 290 nm to 310 nm was 3.09%, and the average optical absorptance in the wavelength range of 350 nm to 500 nm was 0.03%.

[0142] The crystallinity of the tantalum oxide film of Example 3 was amorphous, and the hydrogen content was 6.3 at%. The tantalum oxide film of Example 3 had a light absorptance of 0.14% at a wavelength of 313 nm, and a refractive index of 2.44. The average light absorptance in the wavelength range of 290 nm to 310 nm was 2.23%, and the average light absorptance in the wavelength range of 350 nm to 500 nm was 0.00%.

[0143] The crystallinity of the tantalum oxide film of Example 4 was amorphous, and the hydrogen content was 9.0 at%. The optical absorptance of the tantalum oxide film of Example 4 at a wavelength of 313 nm was 0.07%, and the refractive index was 2.43. The average optical absorptance in the wavelength range of 290 nm to 310 nm was 1.24%, and the average optical absorptance in the wavelength range of 350 nm to 500 nm was 0.01%.

[0144] The crystallinity of the tantalum oxide film of Example 5 was amorphous, and the hydrogen content was 9.6 at%. The optical absorptance of the tantalum oxide film of Example 5 at a wavelength of 313 nm was 0.03%, and the refractive index was 2.43. The average optical absorptance in the wavelength range of 290 nm to 310 nm was 1.19%, and the average optical absorptance in the wavelength range of 350 nm to 500 nm was 0.08%.

[0145] The crystallinity of the tantalum oxide film of Comparative Example 1 was amorphous, and the hydrogen content was 0.2 at%. The tantalum oxide film of Comparative Example 1 had an optical absorptance of 0.42% at a wavelength of 313 nm, and a refractive index of 2.46. The average optical absorptance in the wavelength range of 290 nm to 310 nm was 3.72%, and the average optical absorptance in the wavelength range of 350 nm to 500 nm was 0.01%.

[0146] The crystallinity of the tantalum oxide film of Comparative Example 2 was amorphous, and the hydrogen content was 0.6 at%. The tantalum oxide film of Comparative Example 2 had an optical absorptance of 0.42% at a wavelength of 313 nm, and a refractive index of 2.46. The average optical absorptance in the wavelength range of 290 nm to 310 nm was 3.66%, and the average optical absorptance in the wavelength range of 350 nm to 500 nm was 0.01%.

[0147] In the tantalum oxide film of the embodiment, it is not necessary to positively add impurities other than hydrogen into the tantalum oxide film, and it is preferable that the impurity content X in the tantalum oxide film is smaller than the hydrogen content L (X < L). Here, the impurities are elements other than oxygen, tantalum, and hydrogen, and the impurity content X is the total content of these impurities. The impurity content X in the tantalum oxide film described in the above examples is less than 5.0%, 3.0 at% or less, and 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 may the refractive index decrease due to the addition of impurities, but the light absorption may not necessarily be sufficiently reduced. In the tantalum oxide film of the present embodiment, elements other than tantalum, oxygen, and hydrogen may be contained. For example, the tantalum oxide film described in the above examples may contain argon. This argon is due to the argon gas introduced from the argon gas introduction port 204 during film formation. It is preferable that the argon content M in the tantalum oxide film is smaller than the hydrogen content L (M < L). The argon content M in the tantalum oxide film is, for example, 0.5 to 5 at%.

[0148] This embodiment can achieve a high refractive index and low light absorption while not containing argon. In the tantalum oxide film of the embodiment, it is not necessary to actively add silicon into the tantalum oxide film, and it is preferable that the silicon content O in the tantalum oxide film is less than the hydrogen content L (O < L). The silicon content O in the tantalum oxide film described in the above examples is less than 1 at%, 0.1 at% or less, and less than the detection limit. In the case of a tantalum oxide film added with silicon, not only may fluctuations in the refractive index occur due to the addition of silicon, but light absorption is not necessarily sufficiently reduced. In the tantalum oxide film of the embodiment, it is not necessary to actively add carbon into the tantalum oxide film, and it is preferable that the carbon content P in the tantalum oxide film is less than the hydrogen content L (P < L). The carbon content P in the tantalum oxide film described in the above examples is less than 1 at%, 0.1 at% or less, and less than the detection limit. In the tantalum oxide film of the embodiment, it is not necessary to actively add nitrogen into the tantalum oxide film, and it is preferable that the nitrogen content Q in the tantalum oxide film is less than the hydrogen content L (Q < L). The nitrogen content Q in the tantalum oxide film described in the above examples is less than 1 at%, 0.1 at% or less, and less than the detection limit.

[0149] The inventors have speculated a model in which hydrogen is added to tantalum oxide in hydrogen-containing tantalum oxide. Assuming that tantalum oxide with a hydrogen content of 0 at% is Ta2O5 with a stoichiometric composition, hydrogen-containing tantalum oxide can be modeled as Ta2O5H. x The hydrogen added to Ta2O5 can bond to tantalum or oxygen and terminate the dangling bonds of tantalum or oxygen. Hydrogen may also penetrate between the bonds of tantalum and oxygen or into the lattice. The hydrogen concentration calculated by simulation from this model is about 4×10 20 atoms / cm 3 for a hydrogen content of 1 at%, and about 1×10 21 atoms / cm 3 for a hydrogen content of 3 at%. Also, for a hydrogen content of 6 at%, it is 2×10 21atoms / cm 3 If the hydrogen content is 9 at%, it is 4 × 10 21 atoms / cm 3 If the hydrogen content is 10 at% or more, it is 5 × 10 21 atoms / cm 3 The hydrogen concentration of the tantalum oxide film of this embodiment can be 4×10 20 atoms / cm 3 That's 5 x 10. 21 atoms / cm 3 atoms / cm 3 It is desirable to satisfy an appropriate hydrogen content (at%) within this hydrogen concentration range shown in FIG. 1. Furthermore, the hydrogen concentration of the tantalum oxide film of this embodiment is 1×10 21 atoms / cm 3 It can be more than 2×10 21 atoms / cm 3 It can be more than 4×10 22 atoms / cm 3 However, depending on the amount of impurities such as argon and the packing density of the tantalum oxide film, the hydrogen concentration can be as high as 4×10 20 atoms / cm 3 The hydrogen content may be in the range of 1 to 10 at% or 3 to 9 at% or less, or the hydrogen concentration may be less than 5 × 10 21 atoms / cm 3 The hydrogen content may be in the range of 1 to 10 at % or 3 to 9 at %.

[0150] Since a high-power light source is used in an exposure apparatus, when light from the light source is irradiated onto an optical film formed on an optical element in the apparatus and light absorption occurs in the optical film, this causes an increase in the temperature of the optical element and the atmosphere around it. If thermal expansion occurs in the optical element and the surrounding mechanical parts due to the temperature increase, this can cause a decrease or instability in the imaging performance of the exposure apparatus. In addition, in order to improve the optical characteristics of the optical film, a multi-layered film is generally used, but the more layers there are, the more significant the loss of light quantity due to light absorption becomes, so that a multi-layered film may actually reduce the effective intensity of the exposure light.

[0151] In addition, in the exposure apparatus, a light source with an emission wavelength such as g-line (436 nm) or h-line (405 nm) in the visible region, i-line (365 nm) or j-line (313 nm) in the ultraviolet region, or DUV region (290 to 310 nm) may be used, but the highest achievable resolution depends on the wavelength of the exposure light. The light emitted by the light source of the exposure apparatus (exposure light) may include, for example, light with at least one wavelength within the range of 280 nm or more and 330 nm (e.g., j-line) and light with at least one wavelength within the range of 330 nm or more and 380 nm (e.g., i-line).

[0152] Therefore, in order to stably achieve high resolution, it is desirable to utilize short-wavelength light such as j-line (313 nm) as exposure light. Therefore, it is desirable that the film or layer placed in the optical path is made of a material that has low optical absorption for short-wavelength light such as j-line (313 nm). Furthermore, not only can the resolution be improved, but if the illuminance on the photoresist is increased using light with a wider wavelength band, the exposure time can be shortened and throughput can be improved.

[0153] Tantalum oxide is a material that is widely used in the field of optical devices that handle visible wavelengths because it has a high refractive index in the visible wavelength range. However, tantalum oxide has a relatively large optical absorption in the wavelength range near the j-line, so there is a problem that heat generation and optical loss may occur when it is placed in the optical path of UV light (e.g., j-line).

[0154] For example, as a condition for suppressing the thermal effect on the exposure performance of an exposure device or suppressing the loss of light, the light absorptance of the tantalum oxide film at the wavelength of j-line (313 nm) is 0.40% or less, and more preferably 0.30% or less. In addition, in the wavelength range of 350 nm to 500 nm including g-line, h-line, and i-line, the average light absorptance is 0.10% or less, preferably 0.08% or less, and more preferably 0.05% or less. In the following explanation, those that satisfy these conditions may be described as low absorption.

[0155] Comparing Examples 1 to 5, which contain hydrogen in the range of 1.0 at% or more and less than 10.0 at% in the film, with Comparative Examples 1 and 2, which contain hydrogen less than 1.0 at%, it can be said that both have low absorption in the wavelength range of 350 nm to 500 nm. On the other hand, the optical absorption at a wavelength of 313 nm exceeds 0.40% in Comparative Example 1 and Comparative Example 2, but it was confirmed that Examples 1 to 5 have low optical absorption of 0.40% or less.

[0156] In Fig. 18, the relationship between hydrogen content and light absorptance (wavelength 313 nm) is shown by a dotted line graph, and the relationship between hydrogen content and light absorptance (average value at wavelengths of 350 nm to 500 nm) is shown by a solid line graph. In addition, Fig. 19 shows the absorption spectra of Example 4, Example 5, and Comparative Example 1, and it can be seen that in the wavelength range of 325 nm or less, the light absorptance of the Examples is significantly lower than that of the Comparative Examples.

[0157] 18, in Examples 1 to 5, as the hydrogen content increases from 1.0 at%, the light absorption at a wavelength of 313 nm decreases. Also, when the hydrogen content exceeds 9.0 at%, the light absorption at wavelengths of 350 nm to 500 nm shows an increasing tendency. Thus, it can be seen that the change in light absorption due to the difference in hydrogen content in the film does not show a simple increase or decrease trend across the entire wavelength range, but shows changes with different properties for each wavelength range.

[0158] Figure 24 shows the relationship between the hydrogen content in tantalum oxide and the refractive index at a wavelength of 365 nm. As exemplified by the values ​​at a wavelength of 313 nm (Table 7) and the values ​​at a wavelength of 365 nm (Figure 24), if the hydrogen content is within the range of 1.0 at% or more and less than 10.0 at%, the refractive index is as high as when the hydrogen content is extremely low. For example, the refractive index for light at a wavelength of 313 nm is, for example, 2.40 or more, and can be 2.43 or more.

[0159] As described above, the tantalum oxide film of this embodiment containing hydrogen in the range of 1.0 at% or more and less than 10.0 at% is suitable as a high-performance optical film having a high refractive index and capable of achieving low light absorption in the ultraviolet region including the j-line. Among them, an amorphous tantalum oxide film containing hydrogen at a content of 3.0 at% or more is particularly preferable because it can achieve a high refractive index of 2.40 or more and a low ultraviolet absorption of 0.3% or less. In order to achieve low light absorption in the ultraviolet region including the j-line, the hydrogen content in the tantalum oxide film is preferably 3.0 at% or more, and more preferably 6.0 at% or more. A tantalum oxide film containing hydrogen at a content of more than 9.0 at% can achieve low light absorption even for light with a wavelength of 350 nm to 500 nm. However, a tantalum oxide film of this embodiment containing hydrogen at a content of 9.0 at% or less can achieve particularly low light absorption for light with a wavelength of 350 nm to 500 nm.

[0160] The mechanism by which light absorption increases or decreases depending on the hydrogen content in the tantalum oxide film is thought to be as follows. In order to take into account the differences in the factors that cause absorption for each wavelength range, the first wavelength range is considered to be the wavelength range longer than 320 nm, including the ultraviolet to visible range, and the second wavelength range is considered to be the wavelength range of 320 nm or less, which is near the absorption edge. The absorption edge refers to the wavelength at which absorption due to the size of the band gap begins to occur, and is taken as the wavelength at which 0.3% light absorption occurs as a guideline.

[0161] First, the effect of adding hydrogen is thought to be the reduction of light absorption in the first wavelength region. This is because the cause of light absorption in the first wavelength region is defect levels formed in the band gap. When hydrogen is added to the film, it is expected that the hydrogen will fill the defects and bring about a passivation effect, resulting in a low absorption film. It is also expected to result in a highly durable film with little change in optical properties. However, as can be seen from Comparative Examples 1 and 2, a trace hydrogen content of less than 1.0% has almost no effect on the band gap, so it is not expected to obtain a film with low absorption for light in the second wavelength region.

[0162] In the present embodiment, when the hydrogen content in the tantalum oxide film is 1.0 at% or more and less than 10.0 at%, the light absorption in the first wavelength region is suppressed to a low level due to the passivation effect, and the light absorption in the second wavelength region is also suppressed to a low level due to the appropriate hydrogen content.

[0163] It is believed that the light absorption in the second wavelength region depends on the band gap inherent to the material, tantalum oxide. Dielectric materials such as tantalum oxide have a band gap inherent to the material, and the absorption edge is determined depending on the size of this band gap. In the case of tantalum oxide, inherent light absorption begins to occur at wavelengths shorter than 320 nm. When the hydrogen content is 1.0 at% or more and less than 10.0 at% (preferably 3.0 at% or more and 9.0 at% or less), the amount of hydrogen required to compensate for the defects described above is exceeded, and excess hydrogen is generated in the film. The state of the excess hydrogen in the film at this time is unclear, but it is presumed to be in a state where it is trapped between bonds or in a state where new bonds are generated as OH groups. This affects the band structure inherent to the material itself, and it is believed that the band gap expands and the light absorption edge shifts to the shorter wavelength side. Therefore, it can be presumed that a reduction in light absorption in the second wavelength region has been achieved.

[0164] It is considered that when the hydrogen content in the tantalum oxide film exceeds 9 at%, the amount of excess hydrogen increases, and some of the hydrogen reduces oxygen to create oxygen vacancies, resulting in increased light absorption in the first wavelength region. However, since the reduction effect on light absorption in the second wavelength region (e.g., j-line) is significant, a range of less than 10.0 at% is industrially useful.

[0165] Another factor affecting light absorption is impurities. One possible impurity is Ar that is mixed into the film during film formation, but in all of the above examples and comparative examples, the Ar content in the film was less than 2 at %. In this embodiment, it is found that even when Ar is contained as an impurity, a film with a high refractive index and low light absorption can be realized. In addition, the tantalum oxide film of this embodiment does not contain impurities other than hydrogen and argon, so light absorption caused by elements other than hydrogen and argon does not occur.

[0166] As described above, the present invention uses a tantalum oxide film containing hydrogen within a predetermined range. To be used as a high-performance optical film that has a high refractive index and can achieve low optical absorption in the ultraviolet region (including j-line, for example), the tantalum oxide film of this embodiment containing hydrogen within a range of 1.0 at% or more and less than 10.0 at% is suitable. The tantalum oxide film of this embodiment containing hydrogen within a range of 3.0 at% or more and 9.0 at% or less is even more suitable.

[0167] [Examples 6 to 7], [Comparative Example 3] Next, specific examples in which an optical structure serving as an antireflection structure is constructed using a tantalum oxide film will be described with reference to Examples 6 to 7 and Comparative Example 3. Fig. 20 shows a cross-sectional view of a transmissive optical element provided with an optical structure serving as an antireflection structure.

[0168] The optical element 500 includes a quartz substrate 501 as a base, and an optical structure 502 in which high refractive index layers 502a made of a high refractive index material and low refractive index layers 502b made of a low refractive index material are alternately stacked in a total of six layers.

[0169] The high refractive index layer 502a was formed of tantalum oxide containing hydrogen. The low refractive index layer 502b was formed by using silicon oxide for the second and fourth layers, and magnesium fluoride for the sixth and final layer. Here, in consideration of application to an exposure tool, the physical film thickness of each layer of the optical element 500 was optimized to determine the configuration of the optical structure. That is, the design was made to maximize the anti-reflection characteristics in the wavelength range of 310 nm to 450 nm, including the g-line, h-line, i-line, and j-line, which are characteristic emission lines of the exposure light source. However, it goes without saying that the design can be changed to optimize the anti-reflection characteristics depending on the wavelength range of the light source used.

[0170] Example 6 is an optical element in which high refractive index layers made of tantalum oxide containing 9.0 at % hydrogen as described in Example 4 and the low refractive index layers described above are alternately laminated on a quartz substrate 501.

[0171] Example 7 is an optical element in which high refractive index layers made of tantalum oxide containing 9.6 at % hydrogen as described in Example 5 and the low refractive index layers described above are alternately laminated on a quartz substrate 501.

[0172] Comparative Example 3 is an optical element in which high refractive index layers made of tantalum oxide containing 0.2 at % hydrogen, as described in Comparative Example 1, and the low refractive index layers described above are alternately laminated on a quartz substrate 501. Table 9 shows the specifications of each layer constituting the optical element of Example 6.

[0173] [Table 9]

[0174] Table 10 shows the specifications of each layer constituting the optical element of Example 7. [Table 10]

[0175] Table 11 shows the specifications of each layer constituting the optical element of Comparative Example 3. [Table 11]

[0176] Fig. 21 is a graph showing the reflectance characteristics of the optical structures of Example 6, Example 7, and Comparative Example 3. Fig. 22 is a graph showing an enlarged cut-out of the short wavelength side from Fig. 21. Fig. 23 is a graph showing the transmittance characteristics of the optical structures of Example 6, Example 7, and Comparative Example 3.

[0177] 23, particularly in the ultraviolet region, Examples 6 and 7 achieved higher transmittance than Comparative Example 3. This is consistent with the fact that Examples 4 and 5 obtained tantalum oxide films with high refractive index and low light absorption in the ultraviolet region.

[0178] Also, from FIG. 21, it can be seen that in the wavelength region of 300 nm to 500 nm, Example 6 and Example 7 are equivalent to Comparative Example 3. Also, as shown in FIG. 22, in the DUV region of wavelengths of 290 nm to 300 nm, the reflectance of Example 6 and Example 7 is significantly reduced compared to Comparative Example 3. This suggests that the refractive index for light in the DUV region may change significantly if hydrogen is contained in an amount within a predetermined range. Also, since the refractive index of the tantalum oxide film of Examples 6 and 7 is lower than that of Comparative Example 3, the reflectance theoretically obtained only from the relationship of the refractive index assuming no absorption should be higher in Examples 6 and 7 than in Comparative Example 3. However, the results shown in FIG. 21 and FIG. 22, which take absorption into consideration, show that the difference in reflectance between Examples 6 and 7 and Comparative Example 3 is reduced with respect to the theoretical reflectance, or that the reflectance of Examples 6 and 7 is lower than that of Comparative Example 3. This is presumably due to the effect of absorption on the reflection characteristics. That is, with respect to an optical structure theoretically optimally designed for a virtual complex refractive index (extinction coefficient=0), the imaginary part of the complex refractive index (extinction coefficient) is smaller and the error from the virtual complex refractive index is also smaller in Examples 6 and 7 than in Comparative Example 3. Therefore, it is considered that the deviation from the optimally designed optical structure is smaller in Examples 6 and 7 than in Comparative Example 3, and excellent optical characteristics can be realized.

[0179] From these results, when using a light source with high light intensity of j-line or a wavelength range shorter than that, when constructing an optical structure as an anti-reflection structure, it is preferable that the hydrogen content in the tantalum oxide film is 1.0 at% or more and less than 10.0 at%. It is particularly preferable that the hydrogen content is 3.0 at% or more and 9.0 at% or less.

[0180] In addition, when using a light source that outputs a wide wavelength range including j-line to g-line, when forming an optical structure as an anti-reflection structure using a tantalum oxide film, it is preferable that the hydrogen content in the tantalum oxide film is 1.0 at% or more and less than 10.0 at%. Particularly preferable is a hydrogen content of 3.0 at% or more and 9.0 at% or less, which can achieve low light absorption even for light with a wavelength of 350 nm to 500 nm.

[0181] In this way, by using a tantalum oxide film containing hydrogen within a prescribed range, it is possible to realize a film with small optical loss over a wide wavelength range while maintaining high antireflection properties.

[0182] [Example 8], [Comparative Example 4] Next, specific examples in which an optical structure serving as a reflection structure is formed using a tantalum oxide film will be described with reference to Example 8 and Comparative Example 4. Fig. 25 shows a cross-sectional view of a reflective optical element provided with an optical structure serving as a reflection structure.

[0183] In the optical element 800, a total of 52 high refractive index layers 802a made of a high refractive index material and low refractive index layers 802b made of a low refractive index material are alternately stacked on a quartz substrate 801, which is the base body, to form an optical structure 802.

[0184] The high refractive index layer 802a was formed of tantalum oxide containing hydrogen. The low refractive index layer 802b was formed using silicon oxide. In consideration of the intended use of the optical element 800, the physical film thickness of each layer was optimized to maximize the reflection characteristics in the wavelength range of 310 nm to 450 nm, and the configuration of the optical structure was determined. However, it goes without saying that the design can be changed to optimize the reflection characteristics depending on the wavelength range of the light source used.

[0185] Example 8 is an optical element in which high refractive index layers made of tantalum oxide containing 9.0 at % hydrogen as described in Example 4 and the low refractive index layers described above are alternately laminated on a quartz substrate 801.

[0186] Comparative example 4 is an optical element in which high refractive index layers made of tantalum oxide containing 0.2 at % hydrogen, as described in Comparative Example 1, and the low refractive index layers described above are alternately stacked on a quartz substrate 801.

[0187] Table 12 shows the specifications of each layer constituting the optical element of Example 8. [Table 12]

[0188] Table 13 shows the specifications of each layer constituting the optical element of Comparative Example 4. [Table 13]

[0189] FIG. 26 shows the reflectance characteristics of the optical structures of Example 8 and Comparative Example 4. For example, when comparing the reflectance at 313 nm, Comparative Example 4, which uses tantalum oxide containing 0.2 at % hydrogen, has a reflectance of 98.5%. In contrast, Example 8, which uses tantalum oxide containing 9.0 at % hydrogen, has a reflectance of 99.9%, which is higher than the comparative examples. Since the change in refractive index relative to the hydrogen content is small, it is considered that the difference in reflectance is caused by the magnitude of light absorption in the tantalum oxide film (layer) at around 313 nm. In this way, if a tantalum oxide film containing hydrogen within a predetermined range is used, it is possible to suppress the absorption of ultraviolet light and achieve a high reflectance.

[0190] When using a light source with high light intensity of j-line or a wavelength range shorter than that, in constructing an optical structure as a reflection structure, the hydrogen content in the tantalum oxide film is preferably 1.0 at% or more and less than 10.0 at%. The hydrogen content is particularly preferably 3.0 at% or more and 9.0 at% or less.

[0191] In addition, when using a light source that outputs a wide wavelength range including j-line to g-line, when forming an optical structure as a reflection structure using a tantalum oxide film, it is preferable that the hydrogen content in the tantalum oxide film is 1.0 at% or more and less than 10.0 at%. Particularly preferable is a hydrogen content of 3.0 at% or more and 9.0 at% or less, which can achieve low optical absorption even for light with a wavelength of 350 nm to 500 nm.

[0192] [Example 9], [Comparative Example 5] A specific example in which an optical structure is formed as an anti-reflection structure on the optical surface of at least one lens in a lens group provided in an exposure apparatus will be described. Example 9 is a lens group in which the anti-reflection structure (optical structure) described as Example 6 is provided on both sides of 15 lenses (total of 30 surfaces) provided in an exposure apparatus. That is, in Example 9, an optical structure in which a high refractive index layer made of tantalum oxide containing 9.0 at % hydrogen and a low refractive index layer are alternately laminated is formed on the surface of each lens. Also, Comparative Example 5 is a lens group in which the anti-reflection structure (optical structure) described as Comparative Example 3 is provided on both sides of 15 lenses (total of 30 surfaces). That is, in Comparative Example 5, an optical structure in which a high refractive index layer made of tantalum oxide containing 0.2 at % hydrogen and a low refractive index layer are alternately laminated is formed on the surface of each lens.

[0193] For Example 9 and Comparative Example 5, the transmission loss was measured using 313 nm ultraviolet light in order to evaluate the suitability as a lens for an exposure tool equipped with a light source including wavelengths up to the j-line. Here, the evaluation was performed focusing on the j-line, which is absorbed by conventional tantalum oxide films, but when using a light source with an emission wavelength including infrared light and visible light, it is sufficient to evaluate the suitability as an optical element at the emission wavelength of the light source.

[0194] The evaluation results are shown in Table 14. [Table 14]

[0195] In the lens group of Example 9, each surface can achieve both low light absorptance and low reflectance, and transmission loss can be made extremely small, so that the cumulative transmission loss can be suppressed to 10% or less even for a total of 30 surfaces in 15 lenses. On the other hand, in Comparative Example 5, the light absorptance is significantly increased compared to Example 9, so the transmission loss for a total of 30 surfaces in 15 lenses reaches 15% or more.

[0196] By using the lens group of the ninth embodiment as, for example, an illumination lens group or a projection lens group of an exposure tool, it becomes possible to use ultraviolet light without blocking it, which was previously blocked to prevent heat generation due to light absorption, and this has the effect of increasing the total exposure intensity of the exposure tool, which leads to a reduction in exposure time and makes it possible to improve the processing capacity (throughput) of the exposure tool.

[0197] [Example 10] This shows an example in which a tantalum oxide film (e.g., any of the films of Examples 1 to 5) containing hydrogen in an amount within a predetermined range is applied to an optical component (e.g., a reflecting mirror) of an FPD exposure device used in the manufacture of flat panel displays (FPDs) such as liquid crystal displays. Note that the amount within the predetermined range refers to the hydrogen content (atomic percentage) described in the description of the above examples.

[0198] FIG. 28 is a schematic cross-sectional view showing the configuration of an exposure apparatus 1000 of this embodiment. The exposure apparatus 1000 is a projection exposure apparatus that exposes a circuit pattern formed on a reticle RT onto a processing object GS coated with a photoresist PR, for example, by a step-and-scan method. The exposure apparatus 1000 is preferably used, for example, in the manufacture of liquid crystal displays. The processing object GS is, for example, a glass substrate. The exposure apparatus 1000 also includes an observation mechanism for observing the reticle RT and the processing object GS. As shown in FIG. 28, the exposure apparatus 1000 includes an illumination device 110, a projection optical system 620, a correction optical system 630, and an alignment mechanism 140.

[0199] The illumination device 110 illuminates a reticle RT on which a pattern to be transferred is formed, and includes a light source unit 112 and an illumination optical system 114. The light source unit 112 uses a mercury lamp. Therefore, the light source unit 112 outputs ultraviolet light (wavelengths of 240 nm to 400 nm) including deep ultraviolet light with a wavelength of 300 nm or less. The number of light sources is not limited. The illumination optical system 114 is an optical system that illuminates the reticle RT.

[0200] The illumination optical system 114 includes lenses, mirrors, optical integrators, and apertures. For example, a condenser lens, an optical integrator, an aperture stop, a condenser lens, a slit, and an imaging optical system are arranged in this order. The optical integrator includes a fly-eye lens or an integrator formed by stacking two pairs of cylindrical lens array (or lenticular lens) plates, but may be replaced with an optical rod or a diffraction element. A transmissive optical element (e.g., a lens) included in the illumination optical system 114 is formed with an anti-reflection structure as shown in Example 6 or Example 7. A reflective optical element (e.g., a mirror) included in the illumination optical system 114 is formed with a reflective structure as shown in Example 8.

[0201] The projection optical system 620 is an optical system that projects the pattern of the reticle RT onto the processing object GS. The projection optical system 620 of this embodiment shown in FIG. 28 is composed of a plane mirror 122, a concave mirror 124, and a convex mirror 126, but is not limited to this configuration. The reflection structure of the eighth embodiment is formed on the reflection surfaces of all the mirrors that compose the projection optical system 620. As described above, the reflection mirror having such a reflection structure has extremely small loss due to light absorption and has high reflectance in the exposure light wavelength range, so that high illuminance can be obtained and the exposure process can be performed with high throughput.

[0202] The correction optical system 630 is an optical system that corrects the aberration of 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 made of correction glass having an anti-reflection structure such as that in embodiment 6 or embodiment 7, and is disposed between the reticle RT and the projection optical system 620.

[0203] The alignment mechanism 140 has a function of aligning the reticle RT and the processing object GS, and includes an alignment light source 141, a polarizing plate 145, a half mirror 142, a mirror 143, a polarizing plate 146, and a detector 144. The alignment light source 141 is an illumination light source in the visible light range (wavelength 510 nm or more and 760 nm or less) for alignment. The alignment mechanism 140 is used to align the alignment mark AM2 on the processing object GS with the alignment mark AM1 on the reticle RT. The optical element provided in the alignment mechanism 140 may be provided with an anti-reflection structure as in Example 6 or Example 7, or a reflection structure as in Example 8.

[0204] A light beam from alignment light source 141 is linearly polarized by polarizing plate 145 and illuminates alignment mark AM1 via half mirror 142 and mirror 143. Light reflected by the rear surface of reticle RT passes through mirror 143 and half mirror 142 and enters polarizing plate 146, but polarizing plate 146 is rotated to block the reflected light so that it does not enter detector 144.

[0205] On the other hand, the light that has passed through the alignment mark AM1 enters the projection optical system 620. In this embodiment, the light is set so that a phase difference of 90 degrees occurs before the light reaches the alignment mark AM2 on the object GS after being reflected five times by the plane mirror 122, the concave mirror 124, and the convex mirror 126, and becomes circularly polarized when it arrives.

[0206] The light reflected by the alignment mark AM2 on the object GS passes through the projection optical system 620 again and returns to the reticle RT. At this time, the light beam is given a phase difference again, so the light reaching the reticle RT is linearly polarized. The polarization plane of this light beam is perpendicular to the polarization plane of the illumination light beam incident on the reticle RT. The reflected light from the object GS illuminates the reticle RT, passes through the half mirror 142 and the polarizing plate 146, and is incident on the detector 144. This allows the detector 144 to detect the reticle RT and the object GS. Since the reticle RT and the object GS are in an optically conjugate relationship, the linearly polarized light reflected by the back surface of the reticle RT can be removed to prevent flare caused by the linearly reflected light from the reticle RT. This allows the detector 144 to simultaneously detect images of the reticle RT and the object GS with excellent contrast, enabling highly accurate alignment between the reticle RT and the object GS.

[0207] In the exposure apparatus 1000 of this embodiment, the light beam emitted from the illumination device 110 illuminates the reticle RT, for example, by Kohler illumination. The light that passes through the reticle RT and reflects the reticle pattern is imaged on the processing object GS by the projection optical system 620. In this embodiment, an anti-reflection structure or a reflection structure using a tantalum oxide film containing hydrogen in a predetermined range is provided on the optical surface of the optical element arranged on the optical path, so that loss of the light amount of the exposure light and the alignment light can be suppressed. In particular, it is effective to use a reflection mirror on which a tantalum oxide film containing a predetermined amount of hydrogen is formed in the projection optical system 620.

[0208] The exposure apparatus 1000 of this embodiment can suppress the loss of the light amount of the exposure light and the alignment light, and can perform economical exposure with high resolution and high throughput. Furthermore, since the heat generation of the optical elements due to light absorption is suppressed, it is possible to stably perform high-precision alignment and exposure. Note that the tantalum oxide film containing hydrogen in a predetermined range amount does not necessarily have to be formed on the optical surfaces of all the optical elements arranged on the optical path as in the above example, but may be applied only to any optical surface where it is particularly desired to suppress the absorption of ultraviolet light.

[0209] [Embodiment 4] The substrate on which the optical structure is provided may have an electro-optical structure. The electro-optical structure refers to a structure that converts an electric signal into an optical signal or converts an optical signal into an electric signal. An image pickup element (image pickup device) is a type of optical element because it handles light, and is also a type of semiconductor element (semiconductor device) because it has a photodiode and a transistor. In a back-illuminated image pickup element, a photodiode PD corresponding to each pixel is formed in a semiconductor substrate. The semiconductor substrate functions as a substrate having an electro-optical structure for converting an optical signal into an electric signal, which is realized by the photodiode. In addition, various cameras, including interchangeable lens cameras and lens-integrated cameras, and camera modules for smartphones and in-vehicle use, can be configured using an image pickup element having such an anti-reflection structure. In the camera module, in addition to the lens and image pickup element, a holding part (frame) that holds a plurality of optical components including the lens and image pickup element may be provided. Of course, the lens of the camera module may be coated with a tantalum oxide film.

[0210] The optical element having a substrate having an electro-optical structure may be a liquid crystal display or an organic EL display. A reflection structure may be provided in an organic EL display to increase light utilization efficiency, and an optical structure containing tantalum oxide may be adopted for the reflection structure. In electronic devices such as cameras and smartphones, in addition to an optical element having a substrate having an electro-optical structure, a controller for electrically controlling the electro-optical structure may be provided. If the optical element is an imaging element (imaging device), the electronic device may be provided with a processor for processing a signal output from the imaging element. If the optical element is a display element (display device), the electronic device may be provided with a processor for processing a signal input to the display element. The electronic device to which the present embodiment can be applied may be an information device such as a smartphone or a personal computer. Alternatively, the electronic device may be office equipment such as a printer or a copier, medical equipment such as an X-ray device or an endoscope, industrial equipment such as a robot or a semiconductor manufacturing device, or transportation equipment such as a vehicle, an airplane, or a ship.

[0211] [Example 11] Example 11 shows an example in which a tantalum oxide film containing hydrogen in a predetermined range is applied to an image sensor. Note that the amount within the predetermined range refers to the content (atomic percentage) described in the description of the above examples.

[0212] A solid-state imaging element 900 according to an eleventh embodiment will be described with reference to the cross-sectional view shown in Fig. 29. The solid-state imaging element 900 is a back-illuminated CMOS sensor, but the implementation of the present invention is not necessarily limited to back-illuminated CMOS sensors. That is, the embodiment of the present invention may be a solid-state imaging element in which a tantalum oxide film containing hydrogen in an amount within a predetermined range is disposed in the optical path of imaging light.

[0213] The semiconductor substrate 2 has a first surface on which light is incident and a second surface opposite to the first surface. For example, a Si substrate can be used as the semiconductor substrate 2. The semiconductor substrate 2 includes a photoelectric conversion unit 600 that photoelectrically converts the incident light and accumulates a first charge, and a first transistor 410 having a first gate 390 on the second surface. The semiconductor substrate 2 includes a second transistor 310 having a second gate 290 on the second surface. The first transistor 410 is composed of a source 400, a drain 380, and the first gate 390, and is, for example, an NMOS transistor arranged in a well (P-type well 360) in which holes are the majority carriers.

[0214] An isolation region 120 is provided between the first transistor 410 and the second transistor 310 in a plan view inside the semiconductor substrate 2. This makes it possible to reduce the movement of charges between the first transistor 410 and the second transistor 310. The isolation region 120 may be an insulator or polysilicon embedded in a trench formed in the semiconductor substrate 2, or a material such as these covered with a silicon oxide film. Alternatively, the isolation region 120 may be a metal embedded in the trench.

[0215] In this embodiment, a pixel region 10 is provided in which a plurality of photoelectric conversion units 600 and a plurality of first transistors 410 electrically connected to each of the plurality of photoelectric conversion units 600 are two-dimensionally arranged. A plurality of second transistors 310 are provided outside the pixel region 10. Note that the semiconductor substrate 2 may include one photoelectric conversion unit 600, one first transistor 410, and one second transistor 310.

[0216] The photoelectric conversion unit 600 is, for example, a photodiode. Specifically, the photoelectric conversion unit 600 includes an N-type semiconductor portion that is a part of the upper surface of the semiconductor substrate 2, and a P-type semiconductor portion.

[0217] The pixel region 10 has an effective pixel region 11 including a plurality of photoelectric conversion units 600, and a light-shielded light-shielded pixel region 12 (Optical Black). In the effective pixel region 11, light-shielding walls may be provided to separate the pixels. This can reduce color mixing between pixels. Outside the light-shielded pixel region 12 is a peripheral circuit region 13, which is generally a region that does not have a repeating arrangement structure like the pixel region 10.

[0218] The second transistors 310 are arranged in the peripheral circuit region 13. For example, the second transistors 310 may be provided outside a region in which the lenses and color filters 180 included in the microlens array 190 are two-dimensionally arranged in a planar view, or may be provided in a region outside the separation region 120 in a planar view.

[0219] A vertical scanning circuit, a horizontal scanning circuit, a timing generator, and an output section are arranged in the peripheral circuit region 13. A signal processing section having a signal correction section, an analog-to-digital conversion section, etc. may also be arranged.

[0220] The second transistor 310 includes an NMOS transistor having a second gate 290 on the second surface of the semiconductor substrate 2, and a source 280 and a drain 300 arranged in a P-type well 360. The well 360 in which the source 280 and the drain 300 of the second transistor 310 are arranged forms part of the lower surface and part of the upper surface of the semiconductor substrate 2. For example, this well 360 is arranged continuously from the first surface to the second surface of the semiconductor substrate 2. The peripheral circuit region 13 may further include a PMOS transistor 350 having a source 320 and a drain 340 arranged in an N-type well 370, and a gate 330 on the second surface.

[0221] The first optical film 130 constitutes an anti-reflection structure. The first optical film 130 may be a fixed charge film having a fixed charge of a first polarity (e.g., negative), and has a function of fixing charges of a second polarity (e.g., positive) in the semiconductor substrate 2. The first optical film 130 is provided in a region on the first surface of the semiconductor substrate 2 that overlaps at least the photoelectric conversion unit 600 (electro-optical structure) and the second transistor 310 in a planar view. Here, the "fixed charge" refers to a charge that exists in the film and is fixed without moving due to an electric field or the like. The first optical film 130 is provided at least on the optical path of the imaging light leading to the photoelectric conversion unit 600.

[0222] In this embodiment, the first optical film 130 is provided on the first surface of the semiconductor substrate 2 so as to continuously cover the regions corresponding to the multiple photoelectric conversion units 600, the multiple first transistors 410, and the multiple second transistors 310. That is, the first optical film 130 is provided continuously so as to overlap the multiple photoelectric conversion units 600, the multiple first transistors, and the multiple second transistors in a plan view. The first optical film 130 may be provided, for example, on the entire surface of the pixel region 10 and the peripheral circuit region 13 on the upper surface of the semiconductor substrate 2. This makes it unnecessary to remove the first optical film 130 by etching or the like, and therefore it is possible to suppress damage to the semiconductor substrate 2.

[0223] The first optical film 130 may be provided partially as long as it is a region that overlaps with the photoelectric conversion unit 600 and the second transistor 310 in a plan view and is provided on the first surface of the semiconductor substrate. It is preferable to provide the first optical film 130 on the entire first surface of the pixel region and the peripheral circuit region.

[0224] In the solid-state imaging element 900 of Example 11, the components of the first optical film 130 include a tantalum oxide film containing hydrogen in an amount within a predetermined range. Since the light absorption is low and the transmittance is high, it is possible to suppress a reduction in the amount of imaging light reaching the photoelectric conversion unit 600. The first optical film 130 may be a single layer or a laminate of multiple layers. A preferable configuration of the first optical film 130 includes, for example, an aluminum oxide film and a tantalum oxide film containing hydrogen in an amount within a predetermined range, laminated in this order from the semiconductor substrate 2 side.

[0225] The first optical film 130 is preferably a laminate of multiple layers with different refractive indexes. In this embodiment, a laminate of a first refractive index layer having a refractive index lower than that of the semiconductor substrate 2 and a second refractive index layer having a refractive index lower than that of the first refractive index layer is used in this order from the semiconductor substrate 2 side. This makes it possible to reduce total reflection at the first optical film 130, and therefore allows light to be efficiently incident on the photoelectric conversion section 600.

[0226] In this embodiment, a tantalum oxide film containing hydrogen in an amount within a predetermined range was used for the first optical film 130, but this may also be used for other films provided on the optical path of the imaging light up to the photoelectric conversion unit 600. Note that with regard to the solid-state imaging element of this embodiment, JP 2019-212737 A may be of reference for the parts other than the use of a tantalum oxide film containing hydrogen in an amount within a predetermined range.

[0227] In addition, when manufacturing the solid-state imaging element of this embodiment, ultraviolet reflection from the underlying tantalum oxide film is suppressed in the ultraviolet exposure process for forming the color filter 180 and the microlens array 190. In other words, since ultraviolet halation that reduces patterning accuracy is suppressed, an effect is achieved in that the color filter 180 and the microlens array 190 can be formed with high shape accuracy.

[0228] The imaging element of this embodiment can be suitably used in various cameras including interchangeable lens cameras and integrated lens cameras, camera modules for smartphones and mobile objects (e.g., automobiles and drones), and imaging devices such as ultraviolet cameras. The image captured by the imaging element may be a still image or a video. The imaging device may include a light source (e.g., an ultraviolet light source).

[0229] According to this embodiment, for example, in an imaging element for capturing visible light, the blue pixels can be made sensitive not only to blue light but also to UV light, thereby increasing sensitivity. The imaging element may be an imaging element having a light receiving section (pixel) for detecting UV light in addition to the light receiving sections (pixels) of the R, G, and B colors, or an imaging element having only pixels for capturing UV light. The imaging element of the embodiment can lead UV light to the light receiving section with low loss, thereby achieving high sensitivity.

[0230] The imaging element of this embodiment can be used for applications such as imaging an object illuminated with UV light (e.g., J-rays) to detect fine scratches or defects that are difficult to detect with visible light, sorting plastic materials, etc. Alternatively, it can be used for applications such as imaging power equipment and identifying discharge inspections and discharge locations.

[0231] [Modifications of the third and fourth embodiments] The present invention is not limited to the above-described embodiments and examples, and many modifications are possible within the technical concept of the present invention. For example, a plurality of embodiments can be combined. Some of the features of the embodiments can be deleted or replaced. New features can be added to the embodiments.

[0232] The number of layers constituting the optical structure (for example, anti-reflection structure or reflection structure) according to the present invention, the thickness of each layer, the material used for the low refractive index layer, etc. are not limited to those in the illustrated examples. In short, it is sufficient that the optical structure has tantalum oxide containing hydrogen in the range of 1.0 at% or more and less than 10.0 at% arranged as a high refractive index layer in the optical path of the optical element. In particular, an optical structure using a tantalum oxide film containing hydrogen with a content of 3.0 at% or more and 9.0 at% or less is preferable.

[0233] An optical structure embodying the present invention is preferably provided on the optical path of light having a wavelength within the range of, for example, 290 nm or more and 500 nm or less, but light outside the above range may also be incident on the optical path.

[0234] The optical element having the high refractive index film according to the present invention can be used in optical equipment such as exposure equipment, various cameras, and interchangeable lenses. In these optical equipment, in addition to a plurality of optical components including an optical element coated with a tantalum oxide film containing a predetermined amount of hydrogen, a holding component (e.g., a mirror holder) for holding the plurality of optical components can be provided. In an exposure equipment (e.g., for manufacturing flat panel displays) equipped with an ultraviolet light source, the exposure performance of the exposure equipment can be improved by providing the lens with the anti-reflection structure of the embodiment and / or the mirror with the reflection structure of the embodiment.

[0235] The tantalum oxide film can be applied as a high dielectric constant film not only to optical elements but also to electric elements such as transistors and capacitors. For example, it can be applied to the gate insulating film of semiconductor elements such as MOSFETs and TFTs, and the insulating film (dielectric film) between electrodes of a capacitor element. In these electric elements, by making the hydrogen content of amorphous tantalum oxide 1.0 at% or more, a small leakage current can be achieved, and a high-performance electric element can be realized. In addition, in a crystalline (single crystal or polycrystalline) tantalum oxide film, there was no advantage in making the hydrogen content 1.0 at% or more compared to making the hydrogen content less than 1.0 at%. The tantalum oxide film can also be used as the gate insulating film of at least one of the various transistors in the solid-state imaging element 900 described above. The high dielectric constant film can be widely applied as the gate insulating film of various transistors, and can be implemented in various semiconductor elements such as memories, processors, and logic ICs, and various electronic devices such as smartphones and personal computers.

[0236] The electronic device to which the present embodiment can be applied may be an information device such as a smartphone or a personal computer, or a communication device such as a modem or a router. Alternatively, the electronic device may be an office device such as a printer or a copier, a medical device such as an X-ray device or an endoscope, an industrial device such as a robot or a semiconductor manufacturing device, or a transportation device such as a vehicle, an airplane, or a ship.

[0237] The above-described embodiments can be modified as appropriate without departing from the technical spirit of the present invention. For example, multiple embodiments can be combined. In addition, some features of at least one embodiment can be deleted or replaced. In addition, new features can be added to at least one embodiment.

[0238] The disclosure of this embodiment includes the following configuration. (Configuration 1) A film comprising an amorphous transition metal oxide as a main component, a hydrogen content of 1.0 at % or more, and being an optical film. (Configuration 2) A film comprising an amorphous transition metal oxide as a main component, having a hydrogen content of 1.0 at% or more, and the sum of the transition metal content, oxygen content, hydrogen content, and argon content of 99.0 at% or more. (Configuration 3) 3. The film of claim 1 or 2, wherein the hydrogen content is less than the transition metal content and the oxygen content, and is greater than the argon content. (Configuration 4) 4. The film of any one of claims 1 to 3, wherein the hydrogen content is less than or equal to half the transition metal content. (Configuration 5) 5. The film according to any one of claims 1 to 4, wherein the transition metal oxide is an oxide of a transition metal of Groups 3 to 6. (Configuration 6) 5. The film according to any one of claims 1 to 4, wherein the transition metal oxide is an oxide of a Group 4 or Group 5 transition metal. (Configuration 7) 5. The film of any one of claims 1 to 4, wherein the transition metal oxide is hafnium oxide. (Configuration 8) 8. The film of claim 7, wherein the hydrogen content is 16.0 at % or less. (Configuration 9) 9. The film according to aspect 7 or 8, wherein the hydrogen content is 6.0 at % or more. (Configuration 10) 10. The film according to any one of configurations 7 to 9, wherein the zirconium content is 0.05 at % or more and 0.5 at % or less. (Configuration 11) 11. The film according to any one of configurations 7 to 10, having a refractive index of 2.15 or more for light having a wavelength of 280 nm and an absorptivity of 0.2% or less for light having a wavelength of 280 nm. (Configuration 12) 5. The film of any one of claims 1 to 4, wherein the transition metal oxide is tantalum oxide. (Configuration 13) 13. The film of embodiment 12, wherein the hydrogen content is less than 10.0 at.%. (Configuration 14) 14. The film according to claim 12 or 13, wherein the hydrogen content is 3.0 at % or more. (Configuration 15) 15. The film according to any one of configurations 12 to 14, having an absorptance of 0.40% or less for light having a wavelength of 313 nm and a refractive index of 2.40 or more for light having a wavelength of 313 nm. (Configuration 16) 5. The film according to any one of claims 1 to 4, wherein the transition metal oxide is zirconium oxide or titanium oxide. (Configuration 17) 17. The film according to any one of claims 1 to 16, wherein the argon content is 0.5 at % or more and 5.0 at % or less. (Configuration 18) 18. The film of any one of claims 1 to 17, wherein the content of each of silicon, carbon, and nitrogen is less than 0.5 at %. (Configuration 19) 19. The film of any one of claims 1 to 18, wherein the film has a thickness of 10 nm or more and 1000 nm or less. (Configuration 20) 20. An optical element comprising a substrate and an optical structure formed on the substrate, the optical structure comprising the film according to any one of claims 1 to 19. (Configuration 21) 21. The element according to configuration 20, wherein the optical structure has a structure in which the film and a film having a refractive index smaller than that of the film are alternately laminated. (Configuration 22) 22. The element of claim 20 or 21, wherein the optical structure has an anti-reflection structure. (Configuration 23) 22. The element of claim 20 or 21, wherein the optical structure has a reflective structure. (Configuration 24) 24. The device according to any one of configurations 20 to 23, characterized in that the substrate has an electro-optical structure. (Configuration 25) An apparatus comprising an element according to any one of features 20 to 24, and a holding part for holding a plurality of optical elements including the element. (Configuration 26) 25. An apparatus comprising an element according to any one of configurations 20 to 24 and a light source that generates light to irradiate the film. (Configuration 27) 27. The apparatus of claim 26, wherein the light is ultraviolet light. (Configuration 28) 25. An apparatus comprising the element of configuration 24 and a controller for electrically controlling the electro-optical structure. (Configuration 29) 20. An element comprising the film according to any one of structures 1 to 19, a first portion which is an electrode, and a second portion which is a semiconductor layer or an electrode, wherein the film is disposed between the first portion and the second portion. (Configuration 30) 30. An apparatus comprising: an element according to claim 29; and a controller for electrically controlling the element.

[0239] The disclosure of this specification includes not only what is explicitly described in this specification, but also all matters that can be understood from this specification and the drawings attached hereto. The disclosure of this specification also includes the complement of each individual concept described in this specification. In other words, if this specification contains a statement that "A is B," for example, this specification can be said to disclose that "A is not B," even if the statement that "A is not B" is omitted. This is because when a statement that "A is B" is made, it is assumed that the case in which "A is not B" is taken into consideration.

[0240] In addition, in the specific numerical ranges exemplified in this specification, the description e to f (e and f are numbers) means e or more and / or f or less. In addition, in the specific numerical ranges exemplified, when a range of i to j and a range of m to n are both written (i, j, m, and n are numbers), the combination of the lower limit and the upper limit is not limited to the combination of i and j or the combination of m and n. For example, a combination of the lower limit and the upper limit of multiple combinations may be considered. That is, when a range of i to j and a range of m to n are both written, the range of i to n may be considered, or the range of m to j may be considered, as long as no contradiction occurs. In addition, being e or more means e or larger than e (exceeding e), and a value larger than e may be adopted without adopting e. In addition, being f or less means f or smaller than f (less than f), and a value smaller than f may be adopted without adopting f. [Explanation of symbols]

[0241] [Embodiments 1 and 2] 101: base body / 102: optical structure / 102a: high refractive index layer / 102b: low refractive index layer / 130: semiconductor element / 133: semiconductor layer / 131a: n-channel MOSFET / 131b: p-channel MOSFET / 132a, 132b: gate insulating film / 140: semiconductor element / 141: glass substrate / 142: gate insulating film / 143: semiconductor layer / 144···source electrode / 145···drain electrode / 146···gate electrode / 147···protective film / 150···imaging element / 151···semiconductor substrate / 152···n-type region / 153···p-type region / 154···element isolation region / 155···p-type semiconductor well region / 156···gate electrode / 157···interlayer insulating film / 158···multilayer wiring / 160···anti-reflection structure / 161···Silicon oxide film / 162···Hafnium oxide film / 163···Light-shielding film / 164···Planarization film / 165···On-chip color filter / 166···On-chip microlens / 200···Sputtering deposition device / 201···Vacuum chamber / 204···Argon gas inlet port / 205···Oxygen gas inlet port / 206···Hydrogen gas inlet port / 2 07···Magnetic mechanism / 208···Substrate holding mechanism / 210···Sputtering target / 211···Backing plate / 900···Optical element / 901···Quartz substrate / 902···Optical structure / 902a···High refractive index layer / 902b···Low refractive index layer / 1001···Aluminum / 1002···Optical structure / 1002a···High refractive index layer / 1002b···Low refractive index layer

[0242] [Embodiments 3 and 4] 100...optical element / 101...base / 102...optical structure / 102a...high refractive index layer / 102b...low refractive index layer / 200...sputtering deposition apparatus / 201...vacuum chamber / 202...exhaust system / 203...power source / 204...argon gas inlet port / 205...oxygen gas inlet port / 206...hydrogen gas inlet port / 207...magnet mechanism / 208···substrate holding mechanism / 210···sputtering target / 211···backing plate / 500···optical element / 501···substrate / 502···optical structure / 502a···high refractive index layer / 502b···low refractive index layer / 800···optical element / 801···substrate / 802···optical structure / 802a···high refractive index layer / 802b···low refractive index layer

Claims

1. A substrate, An optical structure formed on the substrate; An optical element comprising: The optical structure includes an optical film; the optical film contains an oxide of a transition metal of periods 4 to 6 and groups 3 to 11, hydrogen, and an element of group 18; In the optical film, the hydrogen content is 1.0 at% or more, and the sum of the transition metal content and the oxygen content is greater than the hydrogen content; The optical element, wherein the optical film is amorphous.

2. A substrate, An optical structure formed on the substrate; An optical element comprising: the optical structure is a laminate in which a third layer is located between a first layer and a second layer, and a second layer is located between the third layer and a fourth layer; the optical film constituting the first layer and the third layer contains an oxide of a transition metal of periods 4 to 6 and groups 3 to 11, and hydrogen; In the optical film, a hydrogen content is 1.0 at% or more, and a sum of a transition metal content and an oxygen content is greater than the hydrogen content; The optical element, wherein the optical film is amorphous.

3. The optical element described in claim 2, characterized in that the optical film contains an element of Group 18.

4. An optical element described in any one of claims 1 to 3, characterized in that in the optical film, the content of Group 18 elements is 0.5 at% or more and 5.0 at% or less.

5. An optical element according to claim 1, wherein the content of Group 18 elements in the optical film is smaller than the content of hydrogen.

6. An optical element described in any one of claims 1 to 3, characterized in that in the optical film, the content of Group 18 elements is 0.5 at% or more and 5.0 at% or less, and the content of the Group 18 elements is smaller than the content of hydrogen.

7. An optical element according to claim 1, wherein the transition metal is a transition metal of Groups 3 to 6.

8. An optical element according to claim 1, characterized in that in the optical film, the hydrogen content is smaller than the transition metal content and the oxygen content.

9. An optical element according to claim 1, wherein the hydrogen content in the optical film is less than half the transition metal content.

10. An optical element according to any one of claims 1 to 3, characterized in that in the optical film, the content of each of the typical elements excluding oxygen, hydrogen and noble gases is less than 1.0 at %.

11. An optical element described in any one of claims 1 to 3, characterized in that the optical film contains a metal element other than the transition metal.

12. The optical element according to claim 11, wherein the metal element is a transition element of the same group as the transition metal.

13. An optical element described in any one of claims 1 to 3, characterized in that in the optical film, the sum of the transition metal content, the oxygen content, the hydrogen content, and the Group 18 element content is 99.0 at% or more.

14. An optical element according to any one of claims 1 to 3, characterized in that the oxide is tantalum oxide or niobium oxide.

15. An optical element according to any one of claims 1 to 3, characterized in that the oxide is hafnium oxide or zirconium oxide.

16. An optical element according to any one of claims 1 to 3; a holding part for holding the optical element, 13. An optical instrument, wherein the optical element is a lens, a mirror, a filter or a prism.

17. An optical element according to any one of claims 1 to 3; A light source that emits light to be irradiated onto the optical film; An optical instrument characterized by:

18. The light includes light having a wavelength of less than 400 nm.

18. Optical instrument according to claim 17.

19. The light includes light having a wavelength of 280 nm or more and 380 nm or less.

18. Optical instrument according to claim 17.

20. An illumination optical system for illuminating a reticle; a projection optical system that projects a pattern of the reticle onto a target object; a correction optical system that corrects aberrations of the projection optical system; and a mechanism for aligning the reticle and the object to be processed, The optical film provided on the optical element included in the above configuration contains an oxide of a transition metal of Groups 3 to 11 and hydrogen, In the optical film, a hydrogen content is 1.0 at% or more, and a sum of a content of the transition metal and a content of oxygen is greater than a content of the hydrogen, The optical device according to claim 1, wherein the optical film is amorphous.

21. The optical device of claim 20, wherein the optical film contains an element of Group 18.

22. The optical device described in Claim 20, characterized in that in the optical film, the content of Group 18 elements is smaller than the content of hydrogen, the content of hydrogen is less than half the content of the transition metal, and the content of oxygen is greater than the content of the transition metal.

23. An optical device according to any one of claims 20 to 22, characterized in that in the optical film, the content of Group 18 elements is 0.5 at% or more and 5.0 at% or less.

Images