Meta-optical element and method for manufacturing meta-optical element

Abstract

This meta-optical element comprises: a support substrate having a first surface and provided with a plurality of openings provided on the first surface side and each surrounded by a side wall and a bottom wall; and a pattern layer including a plurality of embedded members with a component having a refractive index higher than that of a component constituting the side wall being filled into the openings. When a depth C of the openings is 1.0 μm or more, the distance of a portion passing through the center of gravity GA of a cross section at a position of 0.1C from the first surface and having the shortest distance is defined as a distance A, and the distance of a portion passing through the center of gravity GB of a cross section at a position of 0.9C from the first surface and having the shortest distance in the cross section is defined as a distance B, an aspect ratio represented by |C / ((A + B) / 2)| is 3.0 or more, and an angle Φ formed by a line passing through each of the center of gravity GA and the center of gravity GB and a line orthogonal to the first surface is 0.0-10.0°.

Description

Meta-optical element and method for manufacturing meta-optical element

[0001] The present disclosure relates to a meta-optical element and a method for manufacturing a meta-optical element.

[0002] As a lightweight and thin lens, a planar lens having a metasurface (hereinafter sometimes referred to as a metalens) is regarded as a promising candidate. A metalens exhibits the function of a lens by having a metasurface with a fine periodic structure smaller than the incident wavelength. In meta-optical elements such as metalenses, for example, a phase difference is generated by processing a material having a refractive index larger than that of air into a length of a sub-wavelength shorter than the incident wavelength. Generally, materials such as TiO ２ or Si are processed into a nanopillar shape to fabricate a meta-optical element. As an example of a meta-optical element, a metalens having a nanopillar structure of TiO ２ is known (see, for example, Patent Document 1). Also, as an example of a meta-optical element, a metalens in which a finely processed resin is coated with TiO ２ is known (see, for example, Non-Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2018-536204

[0004] Joohoon Kim et al., "Scalable manufacturing of high-index atomic layer-polymer hybrid metasurfaces for metaphotonics in the visible" Nature Materials 22, 474-481 (2023).

[0005] In order to manufacture a meta-optical element having desired performance, such as a metalens with low chromatic aberration and a large numerical aperture (NA), it may be necessary to increase the pillar height. However, the meta-atoms of the nanopillar structure have a problem of low mechanical strength. The present disclosure has been made in view of the above conventional circumstances, and a first aspect of the present disclosure aims to provide a meta-optical element including meta-atoms having excellent mechanical strength. A second aspect of the present disclosure aims to provide a method for manufacturing a meta-optical element including meta-atoms having excellent mechanical strength.

[0006] Specific means for achieving the above problems are as follows. <1> A support substrate having a first surface and provided on the first surface side, the support substrate including a plurality of openings surrounded by side walls and a bottom wall, and a pattern layer including a plurality of embedded members formed by filling at least a part of the openings with a component having a refractive index higher than that of the component constituting the side walls. The embedded members cover the surfaces of the side walls and the bottom wall. The depth C of the openings from the first surface is 1.0 μm or more. When observing the cross section of the openings parallel to the first surface at a position where the depth of the openings from the first surface is 0.1C, the center of gravity G of the cross section, the distance of the shortest portion in the cross section is defined as distance A. When observing the cross section of the openings parallel to the first surface at a position where the depth of the openings from the first surface is 0.9C, the center of gravity G of the cross section, the distance of the shortest portion in the cross section is defined as distance B. The aspect ratio represented by "C / ((A + B) / 2)" is 3.0 or more. The angle Φ formed by the line passing through the center of gravity G and the line passing through the center of gravity G and perpendicular to the first surface is 0.0 to 10.0°. A meta-optical element. <2> The meta-optical element according to <1>, wherein the component constituting the side walls is SiO ２ ２ ２ ２ ２ ２ ​​​​​​​​​​２ O ３ Ta ２ O ３ , Nb ２ O ５ A meta-optical element according to <1> or <2>, wherein the embedded member closes the first surface side of the opening, and when a cross section of the embedded member perpendicular to the first surface is observed, there are intermittent or continuous voids in the cross section extending from the first surface side toward the depth direction of the opening. <5> The meta-optical element according to <4>, wherein the ratio (D / C) of the length of the void to the depth C of the opening is 0.85 to 0.99, when the distance between the outermost end of the first surface side of the void and the outermost end of the bottom wall side of the void is defined as the length of the void. <6> The meta-optical element according to any one of <1> to <3>, wherein the embedded member has a hollow portion that communicates with the outside of the opening. <7> The meta-optical element according to <6>, wherein the ratio (E / C) of the depth E from the first surface in the hollow portion to the depth C of the opening is 0.85 to 0.99. <8> When the angle θ calculated from the following equation (1) based on the distance A, the distance B, and the depth C of the opening is referred to as the taper angle of the opening,

[0007]

[0008] A meta-optical element according to any one of <1> to <7>, wherein the taper angle θ is 0.0° ≤ θ ≤ 2.0°. <9> A method for manufacturing a meta-optical element according to any one of <1> to <8>, comprising: preparing a workpiece having a first surface, wherein the elements constituting the first surface are such that when the element is used as a fluoride, the boiling point of the fluoride is 550°C or less; arranging a catalyst material containing an organic compound having a polar functional group at a location where an opening is formed on the first surface of the workpiece to a thickness of 0.01 μm or more and less than 0.4 μm; exposing the workpiece to a fluorine-containing gas at 80°C or higher to provide a plurality of openings surrounded by side walls and bottom walls on the first surface side of the workpiece; and filling at least a portion of the openings with a component having a refractive index higher than the refractive index of the component constituting the side walls so as to cover the surface of the side walls and the surface of the bottom wall, thereby forming an embedded member. <10> The method for manufacturing a meta-optical element according to <9>, further comprising performing ultraviolet ozone cleaning on the first surface of the workpiece after arranging the catalyst material on the first surface of the workpiece and before exposing the workpiece to a fluorine-containing gas. <11> The method for manufacturing a meta-optical element according to <9> or <10>, wherein the polar functional group comprises at least one selected from the group consisting of a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, a sulfo group, a thiol group, an amide bond, a carbonyl group, a nitro group, a cyano group, an ether bond, and an ester bond. <12> The method for manufacturing a meta-optical element according to any one of <9> to <11>, wherein the embedded member is formed by atomic layer deposition.

[0009] According to a first aspect of this disclosure, a meta-optical element having a meta-atom with excellent mechanical strength can be provided. Furthermore, according to a second aspect of this disclosure, a method for manufacturing a meta-optical element having a meta-atom with excellent mechanical strength can be provided.

[0010] This is an enlarged plan view of a part of the Metalens 10 in the first embodiment. This is a cross-sectional view taken along line A-A in Figure 1. This is a diagram showing an example of a cross-section parallel to the first surface 14 of the opening 12. This is a diagram showing an example of a cross-section parallel to the first surface 14 of the opening 12. This is a diagram illustrating the angle Φ of the opening 12. This is a diagram illustrating the taper angle θ of the opening 12. This is an enlarged end view of a part of the Metalens 210 in the second embodiment. This is a diagram schematically showing the etching mechanism assumed on the first surface of the workpiece when the organic compound does not have polar functional groups. This is a diagram schematically showing the reaction mechanism on the first surface of the workpiece when the organic compound has polar functional groups. This is a cross-sectional view schematically showing how the catalyst material is arranged on the workpiece. This is a diagram schematically showing an example of a cross-section of the workpiece 110 after etching. This is a cross-sectional SEM image of sample 1. This is a cross-sectional SEM image of sample 4. This is a cross-sectional SEM image of sample 5. This is a cross-sectional SEM image of sample 6. This is a cross-sectional SEM image of sample 10.

[0011] In this disclosure, numerical ranges indicated using "~" mean a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, the amount of each component means the total amount of multiple substances if there are multiple substances corresponding to each component, unless otherwise specified. In this disclosure, the terms "layer" or "film" include cases where the layer or film is formed over the entire region when the region in which it exists is observed, as well as cases where it is formed only on a part of the region.

[0012] <Meta-optical element> The meta-optical element of this disclosure comprises a support substrate having a first surface and provided on the first surface side, having a plurality of openings surrounded by a side wall and a bottom wall, and a pattern layer including a plurality of embedded members, wherein at least a portion of the openings is filled with a component whose refractive index is higher than the refractive index of the component constituting the side wall, the embedded members covering the surface of the side wall and the surface of the bottom wall, the depth C of the opening from the first surface being 1.0 μm or more, and when the cross-section of the opening parallel to the first surface at a position where the depth of the opening from the first surface is 0.1 C is observed, the centroid G of the cross-section Ａ Let distance A be the distance between the point passing through and the shortest distance in the cross-section, and when observing the cross-section of the opening parallel to the first surface at a position where the depth of the opening from the first surface is 0.9C, the centroid G of the cross-section Ｂ The aspect ratio expressed as "C / ((A + B) / 2)" when the distance passing through and the shortest distance in the cross-section is taken as distance B is 3.0 or greater, and the centroid G Ａ and the center of gravity G Ｂ The line passing through and the centroid G Ａ The angle Φ formed between the line passing through the first surface and the line perpendicular to it is between 0.0 and 10.0°. Hereinafter, the components constituting the sidewall will also be called "sidewall components," and components with a refractive index higher than that of the sidewall components will also be called "high refractive index components."

[0013] The embedded member constituting the meta-optical element of this disclosure is constructed by filling an opening in a support substrate with a high refractive index component. By providing the embedded member within the opening in the support substrate, the pattern layer (i.e., meta-atom) formed on the surface of the support substrate becomes nearly flat, making it possible to increase the mechanical strength of the meta-atom compared to a nanopillar structure meta-atom where pillars stand upright from the substrate surface, as described in prior art documents. Furthermore, the embedded member constituting the meta-optical element of this disclosure is provided within the opening in the support substrate so as to cover the surface of the side wall and the surface of the bottom wall. Therefore, the overall size and shape of the embedded member are approximately the same as the size and shape of the opening. In other words, the height of the embedded member provided within an opening with a depth C of 1.0 μm or more and an aspect ratio of 3 or more is approximately the same as the depth C of the opening (i.e., 1.0 μm or more), and the overall aspect ratio of the embedded member is approximately the same as the aspect ratio of the opening (i.e., 3.0 or more). Furthermore, the embedded member provided within the opening with an angle Φ of 10.0° or less is located in a direction nearly perpendicular to the first surface. Thus, the embedded member of the meta-optical element of this disclosure is not only nearly perpendicular to the first surface, but also has a high height and a large aspect ratio. Therefore, the meta-optical element of this disclosure is expected to exhibit excellent optical properties.

[0014] The details of the meta-optical elements of this disclosure will be described below with reference to the drawings. In the following description, a meta-lens will be used as an example of a meta-optical element, but the meta-optical elements of this disclosure are not limited to meta-lenses and can be applied to filters, mirrors, splitters, etc. The sizes of the components in each figure are conceptual, and the relative relationships of the sizes of the components are not limited thereto. Also, components having substantially the same function will be given the same reference numeral throughout all drawings, and redundant explanations may be omitted. Furthermore, in the following embodiments, a meta-lens with a cylindrical opening (i.e., a cylindrical embedded component) will be used as an example, but the shape of the opening is not limited to a cylinder, and may be a polygonal prism such as a triangular prism or a rectangular prism.

[0015] (First Embodiment) In the first embodiment, the embedded member closes the first surface side of the opening. Figure 1 is an enlarged plan view of a part of the metalens 10 according to the first embodiment. Figure 2 is a cross-sectional view taken along line A-A, showing a cross-section perpendicular to the first surface 14 through the opening 12 of the metalens 10 shown in Figure 1. Note that in Figure 1, the layer made of high refractive index components (high refractive index material layer 20) present on the first surface 14 is omitted in order to make the location of the opening 12 (embedded member 16) easier to understand. The cross-sectional view taken along line A-A in Figure 2 also corresponds to the cross-section perpendicular to the first surface 14 of the embedded member 16.

[0016] As shown in Figures 1 and 2, the metalens 10 has a support substrate 22 having a first surface 14. On the first surface 14 side of the support substrate 22, there are a number of openings 12 surrounded by a side wall 18 and a bottom wall 24. High refractive index components are filled into the openings 12 to form embedded members 16. The embedded members 16 cover the surfaces of the side wall 18 and the bottom wall 24, and close the first surface 14 side of the opening 12. The number of embedded members 16 then form a pattern layer 26 (i.e., a metaatom).

[0017] Furthermore, a high refractive index material layer 20, composed of the same components as the embedded member 16, is provided on the first surface 14. Preferably, the embedded member 16 and the high refractive index material layer 20 are provided integrally without an interface. In the metalens 10 shown in Figures 1 and 2, the high refractive index material layer 20 is provided on the first surface 14, but the high refractive index material layer 20 is not required. For example, when the embedded member 16 is formed by atomic layer deposition (ALD), which will be described later, the high refractive index material layer 20 is formed together with the embedded member 16. In that case, the high refractive index material layer 20 may be removed after the embedded member 16 and the high refractive index material layer 20 have been formed. Examples of methods for removing the high refractive index material layer 20 include CMP polishing (chemical mechanical polishing).

[0018] Furthermore, the metalens 10 may have other layers depending on the purpose. For example, the metalens 10 may have other layers on the embedded member 16 in Figure 2, or other layers may be formed on the first surface 14 after removing the high refractive index material layer 20 provided on the first surface 14.

[0019] -Support Substrate- The thickness of the support substrate 22 is not particularly limited and is set appropriately according to the application of the metalens 10. The thickness of the support substrate 22 may be, for example, 0.05 to 2 mm.

[0020] The material of the support substrate 22 is not particularly limited, but it is preferable to use a material with excellent light transmittance from the viewpoint of the light transmittance of the metalens 10. From the viewpoint of suitability for manufacturing when applying the manufacturing method of the meta-optical element described later, the support substrate 22 may be a quartz glass substrate, a crystal substrate, a sintered silica particle substrate, or a substrate made of SiO ２ Examples include substrates on which films such as the above have been deposited. In the metalens 10, the material of the support substrate 22 and the components constituting the side wall 18 may be the same. Note that the support substrate 22 may be SiO ２ When using a substrate on which a film has been deposited, it is acceptable to process only the film deposited on the substrate to form the openings and embedded members. In that case, SiO is deposited on a substrate such as a sintered substrate. ２ A film such as the SiO exists, ２ This results in a metalens in which an embedded member is provided in a film such as the above.

[0021] The shape of the support substrate 22 when viewed from above is not particularly limited and can be rectangular, circular, etc., and can be set appropriately depending on the application of the metalens 10. Similarly, the size of the support substrate 22 when viewed from above is not particularly limited and can be set appropriately depending on the application of the metalens 10. For example, if the support substrate 22 is rectangular, it can be a square or rectangle with sides of 2 to 100 mm.

[0022] The pattern layer 26 is formed by a plurality of embedded members 16. The shape of the pattern layer 26 as an aggregate of the plurality of embedded members 16 when the metalens 10 is viewed from above is appropriately set according to the application of the metalens 10, and may be circular, rectangular, or the like. The metalens 10 may be provided with one pattern layer 26 as an aggregate of the plurality of embedded members 16, or it may be provided with two or more pattern layers 26.

[0023] As shown in Figure 2, in the metalens 10, the depth C of the opening 12 is the same as the height C of the embedded member 16. Here, the depth C of the opening 12 is the maximum distance from the first surface to the bottom of the opening 12 in a direction perpendicular to the first surface. The depth C of the opening 12 (i.e., the height C of the embedded member 16) is set to 1.0 μm or more. Because the depth C of the opening 12 is 1.0 μm or more, it becomes possible to set the height C of the embedded member to 1.0 μm or more, making it easier to achieve a phase difference of 2π for the metalens 10, and as a result, it becomes easier to obtain a metalens with low chromatic aberration and a large numerical aperture (NA). The depth C of the opening 12 (i.e., the height C of the embedded member 16) is a value that is appropriately set according to the application of the metalens 10, for example, 1.5 μm or more is preferred, 2.0 μm or more is more preferred, and 3.0 μm or more is even more preferred. The depth C of the opening 12 may be 20.0 μm or less. The depth C of the opening 12 may be 1.0 to 20.0 μm.

[0024] In this disclosure, the depth C of each opening 12 (i.e., the height C of the embedded member 16) refers to a value obtained by observing the cut surface of the metalens 10 (i.e., the cross-section passing through the opening 12 and perpendicular to the first surface 14) using an electron microscope. The individual heights of the five openings 12 are determined by the method described above, and the arithmetic mean of the obtained values ​​is taken as the depth C of the opening 12 (i.e., the height C of the embedded member 16).

[0025] When observing the cross-section 32 of the opening 12 parallel to the first surface 14 at a position where the depth of the opening 12 from the first surface 14 is 0.1C, the centroid G of the cross-section ＡLet distance A be the distance between the points passing through and the shortest distance in the cross-section, and when observing the cross-section 34 of the opening 12 parallel to the first surface 14 at a position where the depth of the opening 12 from the first surface 14 is 0.9C, the centroid G of the cross-section Ｂ The aspect ratio expressed as "C / ((A + B) / 2)" when the distance passing through the point with the shortest distance in the cross-section is denoted as distance B, is set to 3.0 or greater. The aspect ratio for the opening 12 is set to be the same as the aspect ratio for the embedded member 16. In other words, since the aspect ratio of the embedded member 16 in the metalens 10 is 3.0 or greater, it becomes easier to achieve a phase difference of 2π for the metalens 10, and as a result, it becomes easier to obtain a metalens with low chromatic aberration and a large numerical aperture (NA).

[0026] The aspect ratio is preferably 4.0 or higher, more preferably 5.0 or higher, even more preferably 7.0 or higher, particularly preferably 9.0 or higher, and extremely preferably 10.0 or higher. The aspect ratio may also be 50.0 or lower. The aspect ratio is preferably between 3.0 and 50.0. The aspect ratio of the opening 12 is the arithmetic mean of the values ​​obtained by determining the individual aspect ratios for the five openings 12. The individual aspect ratios are determined from distance A, distance B, and depth C obtained by observing the cut surface of the metalens 10 using an electron microscope.

[0027] The following will explain, based on the drawings, the "position where the depth of the opening 12 from the first surface 14 is 0.1C", the "position where the depth of the opening 12 from the first surface 14 is 0.9C", the "cross section parallel to the first surface 14", and the "distance between the centroid of the cross section and the shortest distance in the cross section". The positions where the depth of the opening 12 from the first surface 14 is 0.1C and 0.9C are shown in the opening 12 located on the left in Figure 2. Figures 3A to 3C show examples of cross sections parallel to the first surface 14. Figure 3A(A) shows an example of an opening 12 with a circular cross section, Figure 3B(B) shows an example of an opening 12 with a square cross section, and Figure 3C(C) shows an example of an opening 12 with a rectangular cross section. In Figure 3, the centroid of each shape is represented by the symbol G. Other shapes of the cross section parallel to the first surface 14 include multi-cylinder shapes, cross shapes, etc. Multiple shapes may be combined.

[0028] For an opening 12 with a circular cross-section, the "distance passing through the centroid of the cross-section and the shortest distance in the cross-section" means the diameter of the circle, as shown in Figure 3A(A). For an opening 12 with a square cross-section, the "distance passing through the centroid of the cross-section and the shortest distance in the cross-section" means the length of one side of the square, as shown in Figure 3B(B). For an opening 12 with a rectangular cross-section, the "distance passing through the centroid of the cross-section and the shortest distance in the cross-section" means the length of the shorter side of the rectangle, as shown in Figure 3C(C). Distances A and B may be values ​​obtained from a cross-sectional photograph of the opening 12.

[0029] The ratio (A / B) of distance A to distance B in the opening 12 is preferably 0.90 or more, more preferably 0.95 or more, even more preferably 0.98 or more, and particularly preferably 1.00 or more. The ratio (A / B) in the opening 12 is preferably 1.10 or less, more preferably 1.05 or less, and even more preferably 1.02 or less. The ratio (A / B) in the opening 12 is preferably between 0.90 and 1.10. Note that a ratio (A / B) of 1.00 suggests that cross section 32 and cross section 34 have the same shape. It is preferable that cross section 32 and cross section 34 have the same shape. If the ratio (A / B) is within the above range, it becomes possible to form an opening with the dimensions as designed, and the embedded member formed by filling the opening with a high refractive index component can also be made to the dimensions as designed. As a result, the need to design the opening and embedded member taking into account dimensional errors that may occur in the manufacturing process is reduced, and metalens design becomes easier. Furthermore, if the ratio (A / B) is above the lower limit mentioned above, large voids are less likely to occur, making it easier to obtain a metalens with minimal deviation from the optical design.

[0030] The values ​​of distance A and distance B are appropriately set according to the application of the metalens 10, and for example, they are in the range of 30 to 1000 nm. The values ​​of distance A and distance B may also be in the range of 50 to 500 nm, 100 nm to 500 nm, 300 to 450 nm, 300 to 400 nm, or 300 to 350 nm. The values ​​of distance A and distance B are the arithmetic mean of the individual distances A and B obtained by observing the five apertures 12 using an electron microscope, similar to the aperture depth C. The details of distance A and distance B are as described above.

[0031] -Angle Φ- The opening 12 is at the center of gravity G of the cross-section 32. Ａ and the center of gravity G of cross-section 34 Ｂ A line passing through it, and the center of gravity G ＡThe angle Φ formed by the line passing through and perpendicular to the first surface 14 and is 0.0 to 10.0°. Because the angle Φ of the opening 12 is within this range, the embedded member is positioned in a direction nearly perpendicular to the first surface, making it easier for the function as a meta-optical element to be exhibited. From the viewpoint of improving the optical properties of the meta-lens 10, the angle Φ of the opening 12 is preferably 0.0 to 6.0°, more preferably 0.0 to 5.0°, even more preferably 0.0 to 3.0°, particularly preferably 0.0 to 2.0°, and extremely preferably 0.0 to 1.0°. The angle Φ of the opening 12 will be described below with reference to Figure 4.

[0032] In Figure 4, for the sake of explaining the angle Φ, an opening 12 is shown that is formed at an angle to the first surface, unlike the opening 12 shown in Figure 2, and the void 28, which will be described later, is omitted. Figure 4 shows the centroid G of the cross-section 32 in the opening 12. Ａ and the center of gravity G of cross-section 34 Ｂ The diagram shows a cross-section passing through and perpendicular to the first surface 14. In Figure 4, arrow L represents the thickness direction of the support substrate 22, that is, the direction perpendicular to the first surface 14. In Figure 4, C represents the depth C of the opening described above. Also, H is the centroid G of the cross-section 32 in the direction parallel to the first surface. Ａ From the center of gravity G of cross-section 34 Ｂ This represents the distance to [the specified point]. Using C and H in Figure 4, the angle Φ is determined based on equation (2) below.

[0033]

[0034] The angle Φ expressed by equation (2) is an indicator of the "perpendicularity" of the opening 12. That is, the smaller the angle Φ, the more suppressed the inclination of the support substrate 22 with respect to the thickness direction L in the opening 12 is. The angle Φ of the opening 12 is the arithmetic mean of the values ​​obtained by determining the individual angle Φ for each of the five openings 12. The individual angles Φ are determined using equation (2) from the depth C obtained by observing the cut surface of the metalens 10 using an electron microscope and H shown in Figure 4.

[0035] -Voids- As shown in Figure 2, when observing a cross-section perpendicular to the first surface 14 of the embedded member 16, intermittent or continuous voids 28 exist within the embedded member 16 in the cross-section of the embedded member 16, extending from the first surface 14 side toward the depth direction of the opening 12. Such voids 28 are generated when filling the opening 12 with high refractive index components. In the metalens 10 shown in Figure 2, the voids 28 are formed linearly in the center of the opening 12, that is, away from the side walls 18 on both sides. This phenomenon, where the voids 28 are formed in the center of the opening 12 and their shape is a linear, intermittent or continuous line extending from the first surface 14 side toward the depth direction of the opening 12, is likely to occur when the ALD method, which will be described later, is applied. The ALD method is a method of depositing atomic layers one by one on the wall surface, as will be described later. Therefore, when an embedded member 16 that closes the opening 12 is formed by the ALD method within an opening 12 with a high aspect ratio, atomic layers are deposited from the wall side, causing the cavity to shrink. As the opening 12 closes, a long, narrow, linear cavity remaining in the center of the opening 12 may become a void 28. Although the ALD method is less prone to void formation than other methods (sputtering, CVD, etc.), a linear void in the center of the opening 12, as shown in Figure 2, may occur. The ALD method will be explained below.

[0036] The ALD method is a film deposition method that allows for the formation of atomic layers one by one by alternately introducing a raw material gas containing organometallic materials, metal halides, etc., and an oxidizing agent gas that oxidizes organometallic materials, while the object to be processed is contained in a processing container. The ALD method enables film deposition with superior uniformity of film thickness compared to sputtering, chemical vapor deposition (CVD), etc. When forming the embedded member 16 in the opening 12 using the ALD method, atomic layers are deposited parallel to the side wall 18 of the opening 12 in Figure 2. Therefore, when the taper angle θ of the opening 12, which will be described later, is small, voids 28 that are intermittent or continuous tend to form from the first surface 14 side in the cross-section of the opening 12 toward the depth direction of the opening 12, making it easy to anticipate the location of void 28 in advance. The voids 28 may be formed along the surface direction of the side wall 18. If the locations where voids 28 occur can be anticipated in advance, it becomes possible to design the metalens taking into account the presence of voids 28, thereby improving the performance of the metalens.

[0037] In Figure 2, examples of continuous voids 28 are shown in the left and central embedded members 16, and an example of discontinuous voids 28 is shown in the right embedded member 16. When the length of the void 28 is defined as the distance between the outermost end P on the first surface 14 side of the void 28 and the outermost end Q on the bottom wall side of the void 28, the ratio (D / C) of the length of the void 28 to the depth C of the opening 12 is preferably 0.85 to 0.99. A ratio (D / C) of 0.90 to 0.99 is more preferable, and 0.95 to 0.99 is even more preferable. The voids 28 may be observed discontinuously, as shown in the right embedded member 16 of Figure 2, due to the influence of the preparation process of the test piece used to observe the cross-section of the metalens 10, and the filling material and filling conditions when filling the opening 12 with a high refractive index component to form the embedded member 16. If the void 28 is observed intermittently, the length D of the void in this disclosure is the distance between the outermost end P of the void 28 on the first surface 14 side and the outermost end Q of the void 28 on the bottom wall 24 side. The value of the length D of the void 28 is the arithmetic mean of the individual lengths D obtained by observing the five openings 12 (and embedded members 16) using an electron microscope, similar to the depth C of the openings.

[0038] -Taper Angle θ- The angle (so-called taper angle) between the side wall 18 of the opening 12 and the thickness direction L of the support substrate 22 is preferably 0.0 to 2.0°, more preferably 0.0 to 1.0°, and even more preferably 0.0 to 0.5°. The taper angle θ of the opening 12 will be explained below with reference to Figure 5. In Figure 5, a cylindrical opening 12 is used as an example, but the shape of the opening 12 is not limited to a cylindrical shape. For the sake of convenience in explaining the taper angle, the taper angle θ of the opening 12 shown in Figure 5 is shown in greater emphasis than that of the opening 12 shown in Figure 2. Also, the void 28 is omitted. Figure 5 shows a cross-section that passes through the centroid of the circle of the opening 12 and is perpendicular to the first surface 14 when the cylindrical opening 12 is viewed from above. In Figure 5, the arrow L means the thickness direction of the support substrate 22. In Figure 5, A, B, and C mean the distance A, distance B, and the depth C of the opening, respectively. Based on A, B, and C in Figure 5, the taper angle θ of the opening 12 is determined by the following equation (1).

[0039]

[0040] The taper angle θ expressed by equation (1) serves as an indicator of the "perpendicularity" of the opening 12, similar to the angle Φ. That is, the smaller the taper angle θ, the more suppressed the inclination of the side wall 18 of the opening 12 with respect to the thickness direction L of the support substrate 22. The taper angle θ of the opening 12 is the arithmetic mean of the values ​​obtained by determining the individual taper angles θ for the five openings 12. The individual taper angles θ are determined using equation (1) from distance A, distance B, and depth C obtained by observing the cut surface of the metalens 10 using an electron microscope.

[0041] -Material and characteristics of the embedded member- The material of the embedded member 16 is not particularly limited as long as it is a component with a refractive index higher than the refractive index of the components constituting the side wall 18. ２ In that case, the material of the embedded member 16 is TiO ２ , HfO ２ Al ２ O ３ Ta ２ O ３ , Nb ２ O５ Examples include oxides such as Si; Ge-Sb-S, Ge-Sb-Se, As-S, As-Se, Ge-As-Se, Sb-Se, Ge-Sb-Te, and Ge-Sb-Se-Te chalcogenide compounds; and so on. The components constituting the side wall 18 are SiO ２ In that case, the material of the embedded member 16 is TiO ２ , HfO ２ Al ２ O ３ Ta ２ O ３ , Nb ２ O ５ Preferably, it is at least one selected from the group consisting of Si, Ge-Sb-S chalcogenides, Ge-Sb-Se chalcogenides, As-S chalcogenides, As-Se chalcogenides, Ge-As-Se chalcogenides, Sb-Se chalcogenides, Ge-Sb-Te chalcogenides, and Ge-Sb-Se-Te chalcogenides, and TiO ２ , HfO ２ Al ２ O ３ Ta ２ O ３ , or Nb ２ O ５ It is more preferable that TiO ２More preferably, the refractive index n1 of the component constituting the side wall 18 (i.e., the side wall component) can be, for example, 1.3 to 1.6. From the viewpoint of bringing the coefficient of linear expansion close to that of the embedded member 16, the refractive index n1 of the side wall component is preferably 1.4 to 1.6, and more preferably 1.4 to 1.5. The refractive index n2 of the component constituting the embedded member 16 (i.e., the high refractive index component) can be, for example, 1.7 to 2.6, and from the viewpoint of increasing the refractive index difference with the side wall component, it is preferably 2.0 to 2.6, and more preferably 2.2 to 2.6. The ratio of refractive index n2 to refractive index n1 (n2 / n1) is greater than 1, for example, 1.4 to 2.2. From the viewpoint of increasing the refractive index difference and improving the optical properties of the meta-optical element, the ratio (n2 / n1) is preferably 1.5 or more, and more preferably 1.6 or more. Furthermore, the ratio (n² / n¹) is preferably 2.2 or less, more preferably 2.1 or less, and even more preferably 2.0 or less, from the viewpoint of reducing reflection at the interface.

[0042] (Second Embodiment) The second embodiment is a configuration in which the embedded member has a hollow portion that communicates with the outside of the opening. Figure 6 is an end view showing the end face of the metalens 210 according to the second embodiment that passes through the opening 12 and perpendicular to the first surface 14. Note that the support substrate 22 of the metalens 210 shown in Figure 6 is the same as the support substrate 22 of the metalens 10 shown in Figures 1 and 2, so its description is omitted. In the metalens 210, the embedded member 216 is formed by filling a part of the opening 12 with a high refractive index component. The embedded member 216 covers the surface of the side wall 18 and the surface of the bottom wall 24, and the first surface 14 side of the opening 12 is not closed, and has a hollow portion 228 that communicates with the outside of the opening 12. A pattern layer 226 is formed by a plurality of embedded members 216. In addition, a high refractive index material layer 220 composed of the same components as the embedded member 216 is provided on the first surface 14. The components of the embedded member 216 and the high refractive index material layer 220 are the same as those of the embedded member 16 and the high refractive index material layer 20 in the metalens 10. Also, similar to the high refractive index material layer 20 in the metalens 10, the high refractive index material layer 220 is not required in the metalens 210, and the high refractive index material layer 220 may be removed after the embedded member 216 and the high refractive index material layer 220 have been formed.

[0043] In the metalens 210 shown in Figure 6, the hollow portion 228 is formed in a columnar shape in the center of the opening 12, that is, away from the side walls 18 on both sides. The method for forming the embedded member 216 having the hollow portion 228 is not particularly limited, and for example, the method of forming the embedded member 16 by the ALD method described above can be cited. The ratio (E / C) of the depth E from the first surface 14 in the hollow portion 228 to the depth C of the opening 12 can be, for example, 0.85 to 0.99, and may also be 0.90 to 0.99 or 0.95 to 0.99. The centroid G of the cross-section at a position where the depth of the opening 12 is 0.1C ＡOn the line passing through and with the shortest distance between the openings 12, the ratio (F / A) of the distance F of the hollow portion 228 to the distance A of the opening 12 is, for example, 0.05 to 0.99, and may also be 0.05 to 0.70 or 0.05 to 0.40. Here, the depth E of the hollow portion 228 is the maximum distance from the first surface to the bottom of the hollow portion 228 in a direction perpendicular to the first surface. The ratio (E / C) is the arithmetic mean of the values ​​obtained by calculating the individual ratio (E / C) for each of the five openings 12. Similarly, the ratio (F / A) is also the arithmetic mean of the values ​​obtained by calculating the individual ratio (F / A) for each of the five openings 12. The individual ratios (E / C) and ratios (F / A) are determined from the distance A, depth C, depth E, and distance F obtained by observing the cut surface of the metalens 10 using an electron microscope.

[0044] <Method for Manufacturing Meta-Optical Elements> The meta-optical elements of this disclosure may be manufactured by any method. For example, the meta-optical elements of this disclosure may be manufactured by creating a predetermined opening in a support substrate using deep ultraviolet (DUV) lithography and reactive ion etching (RIE), and then filling the opening with a high refractive index component using the ALD method, CVD method, etc., to form an embedded member. However, openings formed using DUV lithography and RIE may have problems such as tapering of the processed shape or inability to achieve a deep processing depth. Therefore, when manufacturing meta-optical elements using DUV lithography and RIE, it is preferable to use a thick, vertically processed metal film with a high selectivity as a mask material to prevent the occurrence of the above problems.

[0045] The meta-optical element of this disclosure may be manufactured by a method for manufacturing a meta-optical element of this disclosure, which comprises: preparing a workpiece having a first surface, wherein the elements constituting the first surface are elements whose boiling point when the element is converted into a fluoride is 550°C or lower (hereinafter sometimes referred to as a preparation step); arranging a catalyst material containing an organic compound having polar functional groups at locations where openings are formed on the first surface of the workpiece to a thickness of 0.01 μm or more and less than 0.4 μm (hereinafter sometimes referred to as a catalyst arrangement step); exposing the workpiece to a fluorine-containing gas at 80°C or higher to create a plurality of openings on the first surface side of the workpiece surrounded by side walls and bottom walls (hereinafter sometimes referred to as an exposure step); and filling the openings with the high refractive index component to form an embedded member (hereinafter sometimes referred to as a filling step). The method for manufacturing a meta-optical element of this disclosure will be described in detail below. The method for manufacturing a meta-optical element according to this disclosure comprises a preparation step, a catalyst placement step, an exposure step, and a filling step, and may optionally include other steps.

[0046] (Principle) In the method for manufacturing a meta-optical element of the present disclosure, a workpiece prepared in a preparation step undergoes a catalyst placement step, an exposure step, and a filling step to manufacture a meta-optical element. Specifically, by going through the preparation step, the catalyst placement step, and the exposure step, a support substrate having a plurality of openings with a depth C and aspect ratio within the aforementioned range is obtained, and then by going through the filling step, embedded members are formed in the openings to obtain the meta-optical element of the present disclosure. Hereinafter, the method of obtaining a support substrate having a plurality of openings with a depth C, aspect ratio, and angle Φ within the aforementioned range by going through the above preparation step, catalyst placement step, and exposure step will also be referred to as the "specification method". For example, in the case of nanoimprint lithography (NIL), it is difficult to increase the depth C of the openings from the viewpoint of release from the mold, and it is also difficult to make the taper angle of the openings close to zero. In the case of RIE, since the mask is also gradually etched when the substrate is etched, it is difficult to increase the depth C of the openings, and it is also difficult to make the taper angle of the openings close to zero. In contrast, using the above-described identification method makes it easier to control the depth C and aspect ratio of the formed opening within the aforementioned range, and also makes it easier to control the taper angle of the opening to a value close to zero. The principle of obtaining a support substrate having multiple openings in which the depth C, aspect ratio, and angle Φ are within the aforementioned range using the above-described identification method will be explained below.

[0047] The catalyst material contains an organic compound having a polar functional group. Such an organic compound having a polar functional group is thought to play a role in lowering the activation energy of fluoride formation on the surface of the object to be treated. In other words, on the first surface of the object to be treated, the region where the catalyst material is placed (hereinafter referred to as the "coated region") is selectively etched, so that an opening is formed in that region. Furthermore, no significant etching reaction occurs in the region where the catalyst material is not placed (hereinafter referred to as the "uncoated region").

[0048] The role of this will be explained below using Figures 7 and 8. Figures 7 and 8 schematically show the reaction on the surface of the object to be treated where the catalyst material is placed. In the following explanation, as an example, the object to be treated is SiO ２Let's assume that the first surface is hydrogen-terminated. We also assume a hydroxyl group as the polar functional group. First, Figure 7 schematically shows the expected etching mechanism on the first surface of the workpiece when the organic compound does not have a polar functional group. The workpiece is SiO ２ When hydrogen fluoride (HF) gas is supplied from the environment to the region on the surface where the catalyst material is located, i.e., the "coating region," the HF molecule (a) performs a nucleophilic attack on the Si atom (b), as shown in (i). However, for the Si atom (b) to react with the F atom on the surface of the object being treated, the OH group (c) on the surface must interact with the H atom of the HF molecule (a) to weaken the H-F bond, as shown in (ii). In other words, unless energy is provided to break the H-F bond in the HF molecule (a), the H will not react, as shown in (iii). ２ The Si-F bond (d) accompanied by the elimination of O(g) is unlikely to form. However, in this reaction system, there are no substances that contribute to the decrease in the activation energy of the Si-F bond (d). Therefore, significant etching is suppressed in the coated region. In this system, as in normal mask pattern processing, the etching rate tends to be higher in the areas where the workpiece is in direct contact with HF gas, i.e., in the areas where the catalyst material on the surface is not placed, i.e., the "uncoated region".

[0049] On the other hand, Figure 8 schematically shows the reaction mechanism at the first surface of the treated object when the organic compound has a polar functional group. In this case as well, when HF gas is supplied from the environment to the coated region of the catalyst material, the HF molecule (a) performs a nucleophilic attack on the Si atom (b), as shown in (i). However, in the case of Figure 8, in addition to this, the O atom of the -δ part (e) of the polar functional group interacts with the H of the HF molecule (a). Also, the H atom of the +δ part (f) of the polar functional group interacts with the OH group (c) on the surface. Therefore, as shown in (ii), the H-F bond of the HF molecule (a) is weakened. The Si (b)-OH (c) bond is also weakened. As a result, the activation energy required for the bonding reaction between the Si atom and the F atom is reduced. As a result, as shown in (iii), the O atom of the -δ part (e) of the polar functional group removes an H atom from the HF molecule (a), and the H atom of the +δ part (f) reacts with the OH group on the surface, resulting in H ２ O(g) elimination occurs.

[0050] As a result, the Si atom (b) bonds with the fluorine atom. Finally, according to the following reaction equation (2), SiF ４ and H ２ O is formed. SiO ２ +4HF → SiF ４ ↑+ 2H ２ O↑ (2) SiF produced in the reaction ４ and H ２ O is a gas at the processing temperature and is released outside the system. Through the above reaction mechanism, the area directly beneath the coating region of the catalyst material is selectively etched in the object being treated.

[0051] It should be noted that the above reaction is not limited to cases where the polar functional group contains a hydroxyl group. For example, a similar reaction may occur when the polar functional group has at least one selected from the group consisting of an aldehyde group, carboxyl group, amino group, sulfo group, thiol group, and amide bond. Furthermore, Figure 8 illustrates the reaction mechanism using the case where the polar functional group of the organic compound contains a hydrogen atom as an example. However, the polar functional group of an organic compound is not necessarily limited to those containing a hydrogen atom. A similar reaction may occur when the polar functional group does not contain a hydrogen atom and has at least one selected from the group consisting of a carbonyl group, nitro group, cyano group, ether bond, and ester bond.

[0052] (Preparation process) In the preparation process, a workpiece is prepared having a first surface, wherein the elements constituting the first surface are elements whose fluoride has a boiling point of 550°C or less. The workpiece undergoes the catalyst placement process, exposure process, filling process, etc., described later, to form a support substrate and embedded member having multiple openings in the meta-optical element.

[0053] The object to be treated may be composed of a single component or multiple components. When the object to be treated is composed of a single component, the element constituting the first surface of the object to be treated is an element whose fluoride boiling point is 550°C or lower when reacted with fluorine (F) to form a fluoride. By constituting the first surface of the object to be treated with an element whose fluoride boiling point is 550°C or lower, it becomes possible to lower the treatment temperature in the exposure process. For example, the object to be treated may contain at least one element selected from the group consisting of B, C, Si, P, S, Ti, V, Cr, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au. Furthermore, the object to be treated may also contain at least one element selected from the group consisting of H, N, Cl, Br, and O.

[0054] In particular, the element constituting the first surface of the object to be treated is preferably an element whose fluoride, when reacted with fluorine to form a fluoride, has a boiling point of 200°C or lower.

[0055] For example, silicon (Si) is fluoride SiF ４ A workpiece having a boiling point of -86°C and containing silicon as an element constituting the first surface can be suitably used as a workpiece in the method for manufacturing a meta-optical element of this disclosure.

[0056] Al and Ca are fluorides (AlF) ３ ) and (CaF ２ The boiling point of ) exceeds 550°C. Therefore, Al and Ca cannot be said to be elements whose fluorides have a boiling point of 550°C or lower when they react with fluorine (F).

[0057] The material to be treated may be, for example, a quartz glass substrate, a crystal substrate, or a silicon substrate. On the other hand, if the material to be treated is composed of a laminate of multiple members, it is preferable that the element constituting the outermost surface (i.e., the "first surface") of the material to be treated is an element whose fluoride has a boiling point of 550°C or less when reacted with fluorine to form a fluoride. As mentioned above, such an element may be selected from the group consisting of B, C, Si, P, S, Ti, V, Cr, Ge, As, Se, Nb, Mo, Tc, Ru, Rh, Sn, Sb, Te, I, Ta, W, Re, Os, Ir, Pt, and Au. Furthermore, the first surface may also contain at least one element selected from the group consisting of H, N, Cl, Br, and O.

[0058] For example, the object to be processed has one or more films arranged on a substrate, and the outermost film may satisfy the aforementioned characteristics. Alternatively, the entire group of films may satisfy the aforementioned characteristics. Such films may be, for example, SiO ２ Si ３ N ４ The film may have at least one of the following: a film and SiC. Alternatively, the substrate may also have the aforementioned features along with the film. In this case, the substrate may be, for example, a quartz glass substrate, a crystal substrate, or a silicon substrate.

[0059] The size of the object to be processed is not particularly limited; for example, it may be a disc with a diameter of 2.5 to 30 cm. Similarly, the thickness of the object to be processed is not particularly limited; for example, it may be 0.05 to 2 mm.

[0060] (Catalyst placement step) In the catalyst placement step, a catalyst material containing an organic compound having polar functional groups is placed in a film thickness of 0.01 μm or more and less than 0.4 μm at locations where openings are formed on the first surface of the object to be treated.

[0061] The catalyst material comprises an organic compound having a polar functional group. The polar functional group may include at least one selected from the group consisting of, for example, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, a sulfo group, a thiol group, an amide bond, a carbonyl group, a nitro group, a cyano group, an ether bond, and an ester bond. Representative examples of such organic compounds are, for example, phenolic resins, acrylic resins, and methacrylic resins. The catalyst material may consist only of the aforementioned organic compound having a polar functional group, or it may be provided as a mixture with other additives. In the latter case, the catalyst material may include a solvent, a binder, and / or fine particles.

[0062] The method of arranging the catalyst material is not particularly limited. The catalyst material may be arranged on the first surface of the object to be treated by, for example, a coating method, a printing method, a spin coating method, or a spray method. If necessary, the catalyst material may be arranged at locations where openings are formed by a known exposure and development process.

[0063] Figure 9 is a schematic cross-sectional view showing how the catalyst material is arranged on the object to be treated. As shown in Figure 9, the object to be treated 110 has a first surface 112 and a second surface 114. The catalyst material 130 is arranged on a part of the first surface 112 of the object to be treated 110. As shown in Figure 9, the catalyst material 130 is placed at the location R where the opening is formed, forming a covered area. The area outside the covered area is considered an uncovered area.

[0064] The thickness of the catalyst material is set to 0.01 μm or more and less than 0.4 μm. By setting the thickness of the catalyst material within the above range, openings are more easily formed in a direction nearly perpendicular to the first surface 112. As a result, it is easier to obtain openings with small angles Φ and taper angles θ (i.e., high perpendicularity) and large aspect ratios. Furthermore, in order to prevent the film from becoming island-like, the thickness of the catalyst material is preferably 0.05 μm or more. Furthermore, in order to prevent wrinkles from forming in the catalyst film due to exposure to high temperatures during the exposure process, the thickness of the catalyst material is preferably 0.3 μm or less. The thickness of the catalyst material is preferably 0.1 to 0.2 μm. In this disclosure, the thickness of the catalyst material refers to the value measured by SEM observation of the cut surface of the substrate before the exposure process.

[0065] (Cleaning Step) The method for manufacturing a meta-optical element according to the present disclosure may include, after placing a catalyst material on the first surface of the workpiece and before exposing the workpiece to a fluorine-containing gas (i.e., between the catalyst placement step and the exposure step), performing ultraviolet ozone cleaning on the first surface of the workpiece (hereinafter sometimes referred to as the cleaning step). Ultraviolet ozone cleaning can be carried out in an atmosphere gas containing oxygen. Examples of light sources for ultraviolet ozone cleaning include low-pressure mercury lamps, excimer lamps, high-pressure mercury lamps, etc. The processing time may be 5 to 240 minutes. The irradiation dose may be 0.1 to 288 J / cm². ２ That's fine.

[0066] (Exposure Process) In the exposure process, for example, the workpiece 110 on which the catalyst material 130 is placed is housed in a processing chamber. Subsequently, the processing chamber is heated to a predetermined temperature for etching the workpiece, and a fluorine-containing gas is supplied as a processing gas. This exposes the workpiece 110 to the fluorine-containing gas. The processing gas includes hydrogen fluoride gas or fluorine gas. For example, the processing gas may be adjusted to a predetermined concentration using a carrier gas such as argon gas or nitrogen gas. In this case, the concentration of hydrogen fluoride gas or fluorine gas may be in the range of, for example, 0.1 to 100 vol%. The processing temperature is 80°C or higher. If the processing temperature is below 80°C, proper etching selectivity may not occur between the coated and uncoated areas on the first surface of the workpiece. Therefore, the actual processing temperature varies depending on the elements contained in the workpiece 110 (especially the first surface 112) and the shape of the opening, but is usually in the range of 200 to 450°C, and preferably in the range of 250 to 400°C. By setting the processing temperature to 450°C or lower, the deterioration of organic compounds contained in the catalyst material 130 can be suppressed. The processing time is proportional to the depth C of the opening in the support substrate. Therefore, it is preferable to set the processing time so that the depth C of the opening becomes a desired value. Specific processing time values ​​include, for example, 1 to 60 minutes.

[0067] As described above, etching the workpiece 110 under such conditions causes the reaction equation (2) to occur in the coated area. The fluoride and water produced by the reaction escape out of the system as gas. As a result, multiple openings 116 are formed in the coated area of ​​the first surface 112. Figure 10 schematically shows an example of a cross-section of the workpiece 110 after etching.

[0068] (Filling Process) In the filling process, a high refractive index component is filled into the opening 116, and an embedded member is formed within the opening 116. The method for forming the embedded member within the opening 116 is not particularly limited, and methods such as CVD, ALD, sputtering, and vacuum deposition can be used. Among these, the ALD method is preferred because it allows for the filling of a high refractive index component into an opening with an aspect ratio of 3.0 or higher while minimizing the generation of voids.

[0069] For example, TiO ２ When filling, use TiCl as the raw gas. ４ Organic Ti compounds and the like are used, and H is used as the oxidizing gas. ２ Oxygen, ozone, etc., are used. The film formation temperature can be set appropriately depending on the type of raw material gas and oxidizing gas, and may be, for example, 100 to 300°C.

[0070] In the first embodiment described above, the metalens 10 is obtained by filling the high refractive index component in the filling process until the first surface 112 side of the opening 116 is closed. On the other hand, the metalens 210 in the second embodiment described above is obtained by ending the filling process while a cavity remains before the first surface 112 side of the opening 116 is closed.

[0071] (Other steps) In the method for manufacturing a meta-optical element of this disclosure, a step of removing the catalyst material 130 from the first surface 112 may be performed after the exposure step and before the filling step. For example, the catalyst material 130 may be removed by cleaning the workpiece 110 with an acid solution, an alkaline solution, an organic solvent, a corrosive gas, or plasma. Also, as described above, in the method for manufacturing a meta-optical element of this disclosure, in the filling step, an embedded member may be formed in the opening 116, and a high refractive index material layer composed of the same components as the embedded member may be formed on the first surface 112. In the method for manufacturing a meta-optical element of this disclosure, if necessary, a step of removing the high refractive index material layer from the first surface 112 by CMP polishing or the like may be performed after the filling step.

[0072] Through the above process, a meta-optical component can be manufactured that has a pattern layer including multiple embedded members, each provided within a plurality of openings having a depth of 1.0 μm or more and an aspect ratio of 3.0 or more.

[0073] Examples of the present disclosure are described below. In the following description, Examples 1 to 8 are examples, and Example 9 is a comparative example. Examples 10 to 12 are reference examples.

[0074] [Example 1] A synthetic quartz glass substrate with a thickness of 0.5 mm and a refractive index n1 of 1.47 was prepared as the object to be treated (preparation step). Separately, a coating solution containing a catalyst material was prepared. An i-line resist was used as the catalyst material, and the coating solution was prepared by mixing it with a solvent (ethyl lactate, n-butyl acetate). The i-line resist used contains a novolac resin represented by the following chemical formula. Therefore, the i-line resist has a hydroxyl group as a polar functional group.

[0075]

[0076] Next, a coating solution was applied to the first surface of the substrate by spin coating so that the dry film thickness was 0.1 μm. Furthermore, by exposure and development processes, a circular pattern of catalyst material with a diameter of 300 nm and a center-to-center distance of 700 nm was formed on the first surface of the substrate (catalyst placement step). The areas where the catalyst material was placed correspond to the coated regions.

[0077] Ultraviolet ozone cleaning was performed on a substrate with a pattern of catalyst material. A low-pressure mercury lamp (with main wavelengths of 254 nm and 185 nm) was used for the ultraviolet ozone cleaning. The substrate was positioned so that its first surface faced the lamp, and the cleaning was performed for 15 minutes (irradiation dose: 18 J / cm²). ２ The sample was irradiated with DUV to remove organic matter adsorbed on the substrate surface.

[0078] Next, the substrate on which the catalyst material pattern was arranged was cut to dimensions of approximately 20 mm x 20 mm, and the cut sample was placed in the processing chamber with the first surface facing upwards. Gas etching of the sample was then performed in the processing chamber (exposure step). The processing gas was a mixture of nitrogen gas and hydrogen fluoride gas (HF: 20 vol% / N).２ : 80 vol%) was used. The processing temperature was 250 °C. The processing time was 10 minutes.

[0079] Next, O ２ The catalyst remaining on the bottom surface of the opening of the substrate was removed using plasma. The processing conditions were: output: 100 W, chamber pressure: 20 Pa, processing time: 15 minutes.

[0080] Next, TiCl was used as the source gas ４ and H was used as the oxidizing gas ２ O. Under the condition of a film formation temperature of 300 °C, 3126 cycles of depositing atomic layers of TiO ２ on the surface of the side where the opening of the substrate was provided by the ALD method were repeated to fill TiO ２ into the opening, and an embedded member made of TiO ２ was formed in the opening, and a high refractive index material layer (refractive index n2: 2.47), which is a film made of TiO ２ was formed on the first surface (filling step). Through the above steps, Sample 1 of Example 1 was obtained.

[0081] [Examples 2 to 9] Samples 2 to 9 of Examples 2 to 9 were obtained in the same manner as in Example 1, except that the film thickness of the catalyst material arranged in the catalyst arrangement step ("catalyst film thickness" in the table), the processing temperature and processing time in the exposure step, and the film formation temperature and number of cycles in the filling step were as shown in Table 1.

[0082] [Examples 10 to 12] Samples 10 to 12 of Examples 10 to 12 were obtained in the same manner as in Example 1, except that the film thickness of the catalyst material arranged in the catalyst arrangement step ("catalyst film thickness" in the table) and the processing temperature and processing time in the exposure step were as shown in Table 1, and the filling step was not performed.

[0083] <Evaluation> The cut surface of each sample was observed using a scanning electron microscope (SEM), and various dimensions were measured. Table 2 shows the opening distance A, distance B, ratio (A / B), depth C, aspect ratio, angle Φ, and taper angle θ for each example. Table 3 shows the film thickness of the high refractive index material layer ("TiO2 film thickness" in the table), void length D, ratio (D / C), hollow depth E, ratio (E / C), hollow distance F, and ratio (F / A) for Examples 1 to 9. "N.D." in the table means that no void or hollow was observed, and therefore measurement or calculation was impossible. In Examples 1 to 5, the first surface side of the opening was closed by the embedded member, and a linear void was observed in the center of the opening; no hollow was present. In Examples 6 to 8, the opening was not closed by the embedded member, and a columnar hollow was observed in the center of the opening. Therefore, no linear void was observed. In Example 9, the processed shape was curved, and the angle Φ was a large value. Furthermore, the opening was not closed by the embedded member, and a columnar hollow section was observed in the center of the opening. Therefore, no linear voids were observed.

[0084] Figures 11 to 15 show SEM images of the cross-sections of samples 1, 4, 5, 6, and 10 obtained in Examples 1, 4, 5, 6, and 10, respectively.

[0085]

[0086]

[0087]

[0088] As shown in Tables 2-3, in Examples 1-8, by using the manufacturing method of the meta-optical element of the present disclosure, a meta-optical element of the present disclosure was obtained having a pattern layer including a plurality of embedded members provided in a plurality of openings having a depth of 1.0 μm or more, an aspect ratio of 3.0 or more, and an angle Φ of 10.0° or less. The meta-optical elements obtained in Examples 1-8 have embedded members composed of high refractive index components in the openings, and therefore have superior mechanical strength compared to meta-atoms with a nanopillar structure.

[0089] The disclosure of Japanese Patent Application No. 2025-010887, filed on 24 January 2025, is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated as being incorporated by reference.

[0090] 10, 210 Metalens 12, 116 Opening 14, 112 First surface 16, 216 Embedded member 18 Side wall 20, 220 High refractive index material layer 22 Support substrate 24 Bottom wall 26, 226 Pattern layer 28 Void 110 Workpiece 114 Second surface 130 Catalyst material 228 Hollow part

Claims

1. A support substrate having a first surface and provided on the side of the first surface, comprising a plurality of openings surrounded by a side wall and a bottom wall; and a pattern layer comprising a plurality of embedded members, each comprising a component with a refractive index higher than that of the components constituting the side wall, filling at least a portion of the openings, wherein the embedded members cover the surface of the side wall and the surface of the bottom wall, the depth C of the openings from the first surface is 1.0 μm or more, and when the cross-section of the opening parallel to the first surface is observed at a position where the depth of the openings from the first surface is 0.1 C, the centroid G of the cross-section Ａ Let distance A be the distance between the point passing through and the shortest distance in the cross-section, and when observing the cross-section of the opening parallel to the first surface at a position where the depth of the opening from the first surface is 0.9C, the centroid G of the cross-section Ｂ The aspect ratio expressed as "C / ((A + B) / 2)" when the distance passing through and the shortest distance in the cross-section is taken as distance B is 3.0 or greater, and the centroid G Ａ and the center of gravity G Ｂ The line passing through and the centroid G Ａ A meta-optical element in which the angle Φ formed with a line passing through the first surface and perpendicular to it is between 0.0 and 10.0°.

2. The components constituting the side wall are SiO ２ The meta-optical element according to claim 1.

3. A component having a refractive index higher than that of the component constituting the side wall is TiO ２ , HfO ２ , Al ２ O ３ , Ta ２ O ３ , Nb ２ O ５ , Si, Ge—Sb—S-based chalcogenide, Ge—Sb—Se-based chalcogenide, As—S-based chalcogenide, As—Se-based chalcogenide, Ge—As—Se-based chalcogenide, Sb—Se-based chalcogenide, Ge—Sb—Te-based chalcogenide, and Ge—Sb—Se—Te-based chalcogenide, and the meta-optical element according to claim 2, which is at least one selected from the group consisting of 4. The embedded member closes the first surface side of the opening, and when a cross section perpendicular to the first surface of the embedded member is observed, a void exists within the embedded member in the cross section that is intermittent or continuous from the first surface side toward the depth direction of the opening, according to any one of claims 1 to 3.

5. The meta-optical element according to claim 4, wherein the ratio of the length of the void to the depth of the opening C (D / C) is 0.85 to 0.99, when the distance between the outermost end of the first surface side of the void and the outermost end of the bottom wall side of the void is defined as the length of the void D.

6. The embedded member has a hollow portion that communicates with the outside of the opening, as described in any one of claims 1 to 3.

7. The meta-optical element according to claim 6, wherein the ratio (E / C) of the depth E from the first surface in the hollow portion to the depth C of the opening is 0.85 to 0.

99.

8. When the angle θ calculated from the following equation (1) based on the distance A, the distance B, and the depth C of the opening is referred to as the taper angle of the opening, The meta-optical element according to any one of claims 1 to 3, wherein the taper angle θ is 0.0° ≤ θ ≤ 2.0°.

9. A method for manufacturing a meta-optical element according to any one of claims 1 to 3, comprising: preparing a workpiece having a first surface, wherein the elements constituting the first surface are such that when the element is converted into a fluoride, the boiling point of the fluoride is 550°C or less; arranging a catalyst material containing an organic compound having a polar functional group at a location where an opening is formed on the first surface of the workpiece to a thickness of 0.01 μm or more and less than 0.4 μm; exposing the workpiece to a fluorine-containing gas at 80°C or higher to provide a plurality of openings surrounded by side walls and bottom walls on the first surface side of the workpiece; and filling at least a portion of the openings with a component having a refractive index higher than the refractive index of the component constituting the side walls so as to cover the surface of the side walls and the surface of the bottom wall, thereby forming an embedded member.

10. The method for manufacturing a meta-optical element according to claim 9, further comprising performing ultraviolet ozone cleaning on the first surface of the workpiece after placing the catalyst material on the first surface of the workpiece and before exposing the workpiece to a fluorine-containing gas.

11. The method for producing a meta-optical element according to claim 9, wherein the polar functional group comprises at least one selected from the group consisting of a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, a sulfo group, a thiol group, an amide bond, a carbonyl group, a nitro group, a cyano group, an ether bond, and an ester bond.

12. The method for manufacturing a meta-optical element according to claim 9, wherein the embedded member is formed by atomic layer deposition.

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