Superlens, method for manufacturing superlens, electronic device, and method for designing superlens

Abstract

The manufacturing method of the super lens comprises the following steps: a mask pattern forming step of forming a mask pattern on a silicon layer of a substrate with the silicon layer on the surface; an etching step for forming a silicon pattern layer having an array pattern comprising a plurality of silicon pillars or a plurality of pre-oxidation holes by etching the silicon layer; and an oxidation treatment step for oxidizing at least a portion of the silicon in the silicon pattern layer, thereby forming a pattern layer comprising a plurality of silicon oxide pillars or a plurality of holes, the pattern layer having a focal point corresponding to light incident on the pattern layer.

Description

Technical Field

[0001] The present invention relates to a superlens, a method for manufacturing a superlens, an electronic device, and a method for designing a superlens.

[0002] This application claims priority based on Japanese Patent Application No. 2022-114260 filed in Japan on July 15, 2022, and the contents are incorporated herein by reference. Background Art

[0003] Thinner lenses are required for mobile camera modules. In addition, if the lens is heavy, the moment of inertia increases, so lightweight lenses are required in the field of robots.

[0004] As a thin and lightweight lens, for example, a superlens has been proposed. A superlens is an optical element that functions as a lens by having a fine periodic structure that is small relative to the incident wavelength.

[0005] Non-patent document 1 discloses a method of forming SiO 2 A superlens is made by using a pillar.

[0006] Prior art literature

[0007] Non-patent literature

[0008] Non-patent literature 1: Joon-Suh Park, Shuyan Zhang, Alan She, Wei Ting Chen, PengLin, Kerolos MAYousef, Ji-Xin Cheng, and Federico Capasso, "All-Glass, LargeMetalens at Visible Wavelength Using Deep-Ultraviolet ProjectionLithography", Nano Letters, Vol.19, (2019), 8673-8682 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In order to produce a super lens with a short focal length, it is effective to reduce the period (center-to-center distance) of the columnar material. In order to reduce the period of the columnar material, a columnar material with a high aspect ratio is required. In the conventional manufacturing method, for example, the manufacturing method of the super lens of non-patent document 1, the SiO2 is directly etched. 2 , forming SiO 2 Columnar SiO 2 The etching selectivity is low, so if you want to directly etch SiO 2Therefore, in the method of non-patent document 1, only columns with an aspect ratio of 6.6 can be formed, and there is a problem that the focal length becomes longer.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a metalens with a short focal length, a method for manufacturing a metalens, an electronic device, and a method for designing a metalens.

[0012] Technical Solution

[0013] In order to solve the above problems, the present invention proposes the following method.

[0014] (1) A method for manufacturing a metalens is the method for manufacturing a metalens according to claim 1 of the present invention, comprising the following steps:

[0015] A mask pattern forming step of forming a mask pattern on the silicon layer of a substrate having a silicon layer on its surface;

[0016] an etching step of etching the silicon layer to form a silicon pattern layer having an array pattern consisting of a plurality of silicon pillars or a plurality of pre-oxidation holes; and

[0017] an oxidation treatment step of oxidizing at least a portion of the silicon in the silicon pattern layer to form a pattern layer consisting of a plurality of silicon oxide pillars or a plurality of holes;

[0018] The pattern layer has a focal point corresponding to light incident on the pattern layer.

[0019] (2) In aspect 2 of the present invention, in the method for manufacturing a superlens according to aspect 1, the oxidation may be wet oxidation or dry oxidation.

[0020] (3) In the third aspect of the present invention, in the method for manufacturing the metalens of the first or second aspect,

[0021] After the etching process, the following process is also included:

[0022] The substrate having the silicon pattern layer is annealed in a hydrogen atmosphere, an argon atmosphere or a mixed atmosphere of hydrogen and argon.

[0023] (4) In aspect 4 of the present invention, in the method for manufacturing a superlens according to any one of aspects 1 to 3, the mask pattern may be made of resin, silicon oxide, silicon nitride, or aluminum oxide.

[0024] (5) In aspect 5 of the present invention, in the method for manufacturing a superlens according to any one of aspects 1 to 3, the mask pattern may be made of metal.

[0025] (6) In aspect 6 of the present invention, in the method for manufacturing a superlens according to any one of aspects 1 to 5,

[0026] The maximum value of the aspect ratio of the silicon oxide pillars or the holes in the pattern layer is greater than 6.7.

[0027] (7) In aspect 7 of the present invention, in the method for manufacturing a superlens according to any one of aspects 1 to 6,

[0028] The center-to-center distance between the silicon pillars is greater than 1.4 times the width of the silicon pillars.

[0029] (8) In aspect 8 of the present invention, in the method for manufacturing a superlens according to any one of aspects 1 to 7,

[0030] In the etching process, the silicon pattern layer is etched in consideration of expansion of silicon in the oxidation process.

[0031] (9) The metalens of claim 9 of the present invention comprises:

[0032] a support substrate; and

[0033] The pattern layer has an array pattern consisting of a plurality of silicon oxide pillars or a plurality of holes,

[0034] The maximum aspect ratio of the silicon oxide pillars or the holes in the pattern layer is greater than 6.7,

[0035] The pattern layer contains at least SiO 2 .

[0036] (10) In the embodiment 10 of the present invention, in the metalens of the embodiment 9, the pattern layer is made of SiO 2 constitute.

[0037] (11) In aspect 11 of the present invention, in the superlens of aspect 9 or 10, an intermediate layer may be further provided between the supporting substrate and the pattern layer.

[0038] (12) In aspect 12 of the present invention, in the superlens of aspect 9 or 10, the pattern layer may include a folded portion at a location having a phase difference of 360° with respect to the center.

[0039] (13) The electronic device according to claim 12 of the present invention is equipped with the superlens according to any one of claims 9 to 12.

[0040] (14) The method for designing a metalens according to claim 13 of the present invention is a method for designing a metalens, comprising the following steps:

[0041] The phase difference calculation step calculates the phase difference corresponding to the distance r from the center of the metalens based on the wavelength λ of the incident light and the focal length f.

[0042] The columnar size determination step calculates the height H and width a of the silicon oxide column constituting the super lens. x and period Λ x and corresponds to the width a x Phase difference The relationship between the height H and the width a is determined x The range and period Λ x ;as well as

[0043] A columnar width calculation step corresponding to the distance r, after the columnar size determination step, according to the phase difference corresponding to the distance r and corresponds to the width a x Phase difference , the width a corresponding to the distance r from the center of the metalens is calculated x ;

[0044] In the phase difference calculation step, the phase difference corresponding to the distance r When the angle is 360° or more, the following formula (A) and formula (B) are satisfied to calculate the angle.

[0045]

[0046] In the above formula (A), n is a natural number.

[0047] (15) In aspect 15 of the present invention, the method for manufacturing a superlens according to any one of aspects 1 to 8 may further include a step of performing the method for designing a superlens according to aspect 14.

[0048] Effects of the Invention

[0049] According to the above-mentioned scheme of the present invention, it is possible to provide a metalens with a short focal length, a method for manufacturing a metalens, an electronic device, and a method for designing a metalens. In particular, it is possible to provide a method for utilizing the excellent etching selectivity of Si and being able to heat-oxidize SiO 2 A method for producing a special effect of a chemical. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 (a) is an example of a top view in which a part of the array pattern of the metalens of the first embodiment is enlarged. Figure 1 (b) is Figure 1(a) is a cross-sectional view of the metalens along line AA.

[0051] Figure 2 It is the equivalent refractive index n when the wavelength of the incident light is 632.8nm 2D With the occupancy rate f x Graph of the relationship.

[0052] Figure 3 This is a flowchart of the method for designing the metalens according to the first embodiment.

[0053] Figure 4 is the phase difference corresponding to the distance from the center of the lens FIG. 1 is a diagram of an example of the calculation results.

[0054] Figure 5 is the phase difference corresponding to the distance from the center of the lens FIG. 1 is another example of the calculation results.

[0055] Figure 6 is the width a corresponding to the silicon oxide column x Phase difference FIG. 1 is a diagram of an example of the calculation results.

[0056] Fig. 7A This is a diagram showing an example of a pattern model of a designed super lens.

[0057] Figure 7B Yes Fig. 7A A magnified view of a portion of the metalens.

[0058] Figure 7C Yes Fig. 7A A magnified view of a portion of the metalens.

[0059] Figure 8 This is a flowchart of the method for manufacturing the superlens according to the first embodiment.

[0060] Fig. 9 is a cross-sectional view showing an example of a manufacturing process of a method for manufacturing a metalens according to the first embodiment, Fig. 9 (a) is a diagram showing a mask pattern forming process, Fig. 9 (b) is a diagram showing an etching process, Fig. 9 (c) is a diagram showing the oxidation treatment step.

[0061] Fig.10 (a) is a plan view showing a part of the array pattern of the super lens of the second embodiment after enlargement. Fig.10 (b) is Fig.10 (a) is a cross-sectional view of the metalens along line CC.

[0062] Fig.11 This is a graph showing the relationship between the width (nm) of a silicon pillar and the expansion rate of the width of the pillar.

[0063] Fig.12 is a schematic diagram of a focal length evaluation device.

[0064] Fig.13 The relationship between the distance r from the center of the lens and the brightness when the height of the metalens oxidized for 1 hour is changed and measured Fig.13 (a)~ Fig.13 (c). Fig.13 (a) shows the relationship between the distance r from the lens center and the brightness in the range of Z=0 μm to Z=500 μm. Fig.13 (b) shows the relationship between the distance r from the lens center and the brightness when Z=600 μm. Fig.13 (c) shows the relationship between the distance r from the lens center and the brightness in the range of Z=700 μm to Z=1400 μm.

[0065] Fig.14 is with Fig.13 (a)~ Fig.13 (c) is a graph showing the relationship between the distance r from the center of the lens and the brightness when the height of the metalens oxidized for 3 hours is changed and measured.

[0066] Fig.15 is the design value W for the column d and the measured value W of the width of the silicon oxide column mp With the set value W d A graph showing the results of linear approximation of the ratio γ.

[0067] Fig.16 This is a graph showing the relationship between the distance r from the center of the lens and the brightness when the height of the super lens of Example 2 is changed and measured. DETAILED DESCRIPTION

[0068] <First Embodiment>

[0069] Hereinafter, a metalens according to a first embodiment of the present invention will be described with reference to the drawings. Figure 1 (a) is a plan view in which a part of the array pattern of the superlens 100 according to the first embodiment is enlarged. Figure 1 (b) is Figure 1(a) is a cross-sectional view of the super lens 100 along the AA line. The super lens 100 is provided in sequence with: a supporting substrate 15; and a pattern layer 20 having an array pattern composed of a plurality of silicon oxide columns 22. The super lens 100 of the first embodiment is a reflective super lens that reflects incident light. In the following description, in the first embodiment, the X direction is a direction parallel to the surface 12a of the intermediate layer 12 provided between the supporting substrate 15 and the pattern layer 20, and is one of the directions in which the silicon oxide columns 22 are arranged. It should be noted that the surface 12a and the intermediate layer 12 opposite to each other across the supporting substrate 15 are formed when the supporting substrate 15 is subjected to a thermal oxidation treatment, and may not affect the optical function of the super lens 100. The Y direction is a direction parallel to the surface 12a of the intermediate layer 12, and is a direction intersecting the X direction. For example, the Y direction is substantially orthogonal to the X direction. The Z direction is a thickness direction of the supporting substrate 15, and is a direction intersecting the X direction and the Y direction. Below, each component is described.

[0070] (Support substrate 15)

[0071] The support substrate 15 is not particularly limited as long as it can form the reflective superlens 100. Silicon (Si) is preferably used as the material of the support substrate 15. The thickness of the support substrate 15 is not particularly limited as long as it can hold the pattern layer 20.

[0072] (Middle layer 12)

[0073] In the super lens 100, an intermediate layer 12 is provided between the support substrate 15 and the pattern layer 20. Specifically, the intermediate layer 12 is provided on the support substrate 15. The material of the intermediate layer 12 is not particularly limited as long as it can function as the reflective super lens 100. The material of the intermediate layer 12 is, for example, silicon dioxide (SiO 2 The thickness of the intermediate layer 12 is not particularly limited as long as it can function as a reflective super lens 100. The thickness of the intermediate layer 12 is, for example, 1 μm to 20 μm. In the super lens 100, incident light passing through the pattern layer 20 is reflected at the interface between the intermediate layer 12 and the supporting substrate 15.

[0074] (Pattern layer 20)

[0075] In the first embodiment, the pattern layer 20 is provided on the intermediate layer 12. The pattern layer 20 has an array pattern 26 composed of a plurality of silicon oxide pillars 22. Here, the array pattern refers to a pattern in which microstructures (for example, silicon oxide pillars 22) are regularly arranged in the X direction and the Y direction at a predetermined interval (center-to-center distance). The pattern layer 20 contains at least SiO 2 The pattern layer 20 may also contain Si. 2When it is composed of Si, the refractive index of Si is higher than that of SiO. 2 The refractive index of the pattern layer 20 is high, so the 2 The pattern layer 20 can also be made of SiO 2 The pattern layer 20 is composed of SiO 2 In the case of the pattern layer 20, SiO 2 Compared with the case of Si, the transmittance to the incident light can be improved. The pattern layer 20 has a folded portion at a position where the phase difference is 360° relative to the center of the super lens 100. The folded portion refers to a position where the phase difference along the radial direction from the center of the super lens 100 is from 360° to 0°.

[0076] The pattern layer 20 has a focal point corresponding to the incident light. The focal length of the pattern layer 20 is appropriately set according to the design of the superlens 100. For example, when the wavelength of the incident light is a visible light wavelength (wavelength: 400nm to 800nm), the focal length of the pattern layer 20 is, for example, 500μm to 2500μm.

[0077] The shape (planar shape) of the silicon oxide columnar member 22 viewed from the Z direction is not particularly limited, and may be a polygon, a circle, etc. In the first embodiment, the planar shape of the silicon oxide columnar member 22 is a square. The width a of the silicon oxide columnar member 22 in the X direction is x and the width a in the Y direction y The width a of the silicon oxide columnar member 22 in the X direction is appropriately set according to the design of the super lens 100. x For example, the width a of the silicon oxide pillar 22 in the Y direction is 150 nm to 600 nm. y For example, it is 150nm to 600nm.

[0078] The center-to-center distance (period) of the silicon oxide pillars 22 along the X direction as viewed from the Z direction is Λ x The center-to-center distance (period) of the silicon oxide columnar member 22 along the Y direction is Λ y The period Λ of the silicon oxide columnar structure 22 along the X direction is appropriately set according to the design of the super lens 100. x For example, it is 200 nm to 600 nm. The period Λ of the silicon oxide pillars 22 along the Y direction y For example, it is 200nm to 600nm. Preferably, the period Λ x With period Λ yIt should be noted that the center of the silicon oxide column 22 observed from the Z direction is the center of the smallest containing circle when the planar shape of the silicon oxide column 22 is a polygon, and is the center of the circle when the planar shape of the silicon oxide column 22 is a circle. Here, the smallest containing circle refers to the smallest circle that completely contains the polygon.

[0079] The length (height) H of the silicon oxide pillar 22 in the Z direction is appropriately set according to the design of the super lens 100. The height H of the silicon oxide pillar 22 is 1.0 μm to 3.0 μm.

[0080] The height H of the silicon oxide pillar 22 and the width a of the silicon oxide pillar 22 in the X direction are x The aspect ratio (H / a x ) is appropriately set according to the design of the superlens 100. Aspect ratio (H / a x ) is greater than 6.7. A more preferred aspect ratio (H / a x ) is greater than 7.0. Similarly, as the height H of the silicon oxide columnar member 22 and the width a of the silicon oxide columnar member 22 in the Y direction, y The aspect ratio (H / a y The maximum value of ) is also appropriately set according to the design of the metalens 100. y ) is greater than 6.7. A more preferred aspect ratio (H / a y ) is greater than 7.0. When the planar shape of the silicon oxide columnar material 22 is a square or a circle, the aspect ratio (H / a x ) and aspect ratio (H / a y That is, in this case, the aspect ratio of the silicon oxide pillar 22 is the ratio of the width to the height.

[0081] Next, the relationship between the array pattern 26 of the silicon oxide columnar material 22 and the lens function is described. The array pattern 26 of the silicon oxide columnar material 22 has a periodic structure that is smaller than the incident wavelength. The periodic structure can be regarded as an optical medium with a uniform refractive index. Figure 1 (a) and Figure 1 The refractive index of the silicon oxide columnar material 22 in (b) is set to n 1 , let the refractive index of the surrounding medium be n 2 , the refractive index of TE wave (Transverse Electric Wave) is set to n TE , let the refractive index of TM wave (Transverse Magnetic Wave) be n TM , then the equivalent refractive index n 2DIt is expressed by the following formula (1). In addition, n in formula (1) TE It is expressed by the following formula (2), where n in formula (1) is TM It is expressed by the following formula (3). x is the occupancy in the X direction and is expressed by the following formula (4). y is the occupancy in the Y direction and is expressed by the following formula (5). x is the width of the silicon oxide column 22 in the X direction, Λ x is the center-to-center distance (period) of the silicon oxide pillars 22 along the X direction. y is the width of the silicon oxide column 22 in the Y direction, Λ y is the center-to-center distance (period) of the silicon oxide pillars 22 along the Y direction.

[0082] [Formula 1]

[0083]

[0084] Figure 2 The equivalent refractive index n is when the wavelength of the incident light is 632.8nm. 2D With the occupancy rate f x relationship. Figure 2 is to convert the above formula (1) into 1 As SiO 2 The refractive index of the surrounding medium is 1.457. 2 The result of the calculation is when the refractive index of air is 1. In the first embodiment, since it is a square, f x =f y . Figure 2 The vertical axis is the equivalent refractive index n 2D , the horizontal axis is the occupancy rate f x .like Figure 2 As shown, we can know that the occupancy rate f x The higher the equivalent refractive index n 2D By changing the occupancy, the equivalent refractive index n 2D The refractive index distribution allows the super lens 100 to function as a lens. It should be noted that the optical path length when light waves pass through the pattern layer 20 is calculated by multiplying the height H of the silicon oxide columnar object 22 by the equivalent refractive index n 2D The obtained n 2D H means.

[0085] In the superlens 100 of the present embodiment, since the aspect ratio of the silicon oxide pillars 22 is high, the focal length can be shortened to, for example, 500 μm to 2500 μm. The details will be described later.

[0086] In the first embodiment, the superlens 100 includes the intermediate layer 12 , but the superlens 100 may not include the intermediate layer 12 as long as it can reflect incident light.

[0087] The superlens 100 of the first embodiment may have warp.

[0088] In addition, the silicon oxide pillars 22 are not limited to being completely perpendicular to the surface 12a of the intermediate layer 12. The width a of the silicon oxide pillars 22 is x 、a y The height H of the silicon oxide columnar structure 22 is not limited to being uniform, but may be non-uniform, with a design error of about 1% to 5%. x 、a y The aspect ratio can also be greater than 6.7.

[0089] <Method for Designing Super Lens 100>

[0090] Next, an example of a method for designing the superlens 100 according to the first embodiment will be described. Figure 3 1 is a flow chart of the design method of the metalens 100 of the first embodiment. Here, the case where the planar shape of the silicon oxide column 22 is a square is taken as an example for explanation, but the same method can be used to design the metalens in the case of other planar shapes such as a circle. The planar shape of the silicon oxide column 22 is a square here, so the width a of the silicon oxide column 22 is x The width a of the silicon oxide columnar member 22 in the Y direction is y In the case of a circle, the width a x The period Λ of the silicon oxide columnar material 22 in the X direction is x The period Λ in the Y direction of the silicon oxide column 22 y same.

[0091] (Initial setting process)

[0092] The design method of the metalens 100 includes an initial setting step S30 and a calibration step S31. The initial setting step S30 is described below. The initial setting step S30 includes the following steps: a phase difference calculation step S10, in which a phase difference corresponding to a distance r is calculated based on the wavelength λ of the incident light and the focal length f. As a function of the distance r from the center of the super lens; columnar size determination step (size determination step) S11, calculate the height H and width a of the silicon oxide columnar member 22 constituting the super lens 100 x and the period Λx corresponding to the width a x Phase difference The relationship between the height H and width a of the silicon oxide column 22 is determined by x and the column width calculation step S12 corresponding to the distance r, after the size determination step S11, according to the phase difference corresponding to the distance r The width a of the silicon oxide column 22 corresponds to x Phase difference The width a of the column corresponding to the distance r from the center of the metalens is calculated based on the relationship between x The following describes each calculation process.

[0093] (Phase Difference Calculation process)

[0094] In phase difference In the calculation step S10, first, the wavelength of the incident light, the focal length f, and the lens diameter D are set. Here, as an example, the wavelength λ of the incident light is set to 532nm, the focal length f is set to 1000μm, and the lens diameter D is set to 100μm. These values ​​can be changed appropriately according to the purpose. The phase difference corresponding to the distance r (distance in the radial direction) from the center of the lens is It is calculated by the following formula (6). In the following formula (6), λ represents the wavelength of the incident light, r represents the distance from the center of the lens, and f represents the focal length.

[0095] [Formula 2]

[0096]

[0098] Formula (6) shows that the shorter the focal length f, the larger the phase difference Φ(r). For example, in the case of a large focal length value fa and a short focal length value fb, at a distance r1 from the center of the lens, the phase difference value of fb is larger than the phase difference value of fa. As described above, the optical path length (i.e., the phase difference) is the value obtained by multiplying the height of the silicon oxide column by the equivalent refractive index, so the higher the height of the silicon oxide column, the larger the phase difference obtained, and thus a short focal length can be obtained.

[0099] Figure 4 is the phase difference calculated using the above formula (6) An example of . Figure 4 The horizontal axis represents the distance r (μm) from the center of the lens, and the vertical axis represents the phase difference (°). In the calculation of , since the phase is equal every 360°, the phase difference can be folded. Specifically, as the distance r increases, the phase difference Increase, in phase difference When the angle is 360° or more, the following formula (A) and formula (B) are satisfied to calculate the angle. In the following formula (A), n is an arbitrary natural number. Figure 5 This is an example of a case where the phase difference is folded every 360°. Figure 5 The horizontal axis represents the distance r (μm) from the center of the lens, and the vertical axis represents the phase difference (°). By making the phase difference in the super lens 100 range from 0° to 360°, the silicon oxide columnar material 22 of the same width can be repeatedly used for the super lens periodically. Since the designed silicon oxide columnar material 22 is limited to a specific range, the width of the silicon oxide columnar material 22 can be controlled within a certain range. As a result, the yield of the super lens 100 can be improved.

[0100]

[0101] (Columnar Object Size Determination Step S11)

[0102] In the columnar size determination step S11, the height H and width a of the silicon oxide columnar 22 constituting the superlens 100 are calculated. x , period Λ x The relationship between the height H and the width a of the silicon oxide column 22 is determined by x The range and period Λ x The width a of the silicon oxide column 22 is x 、Center distance (period) Λ x In calculating the relationship between the height H and the phase difference, for example, the Rigorous Coupled Wave Analysis can be used. x and height H and changing the width of the silicon oxide column 22 to adjust the equivalent refractive index n 2D The method of distribution is described below, but the present invention is not limited to this.

[0103] The height H of the silicon oxide column 22 is fixed, and the width a of the silicon oxide column 22 serving as a reference is x Set as the lower limit, fixed period Λ x , calculate the width a corresponding to the silicon oxide column 22 x Phase difference The width a of the silicon oxide columnar member 22 serving as a reference x It can also be set to the minimum width of the silicon oxide column 22 that can be formed. x This corresponds to the width a of the silicon oxide column 22. x Phase difference Calculation. Figure 6The width a corresponding to the silicon oxide columnar member 22 is calculated by setting the height H of the silicon oxide columnar member 22 to 2.5 μm and the wavelength of the incident light to 532 nm. x Every cycle Λ x Phase difference Example. Figure 6 The horizontal axis is the width a of the silicon oxide column 22. x (nm), the vertical axis is the phase difference (°). Phase difference By x The phase value is subtracted from the lower limit a x The phase value is calculated. Figure 6 In the case of changing the period Λ x When the width a of the silicon oxide columnar member 22 is set to 400 nm, x The phase difference can be controlled within the range of 0° to 360° by setting the phase difference to 192nm to 340nm. The period Λ is set so as to be within the range of 0° to 360° x .

[0104] In addition, if Figure 6 As shown, the width a of the column x It cannot be greater than the value of the period, so a high height means a large aspect ratio. Therefore, the metalens 100 provided by the present invention with an aspect ratio greater than 6.7 is extremely valuable.

[0105] (Step of calculating the column width corresponding to the distance r)

[0106] In the columnar width calculation step S12 corresponding to the distance r, the phase difference corresponding to the distance r is calculated. The width a of the silicon oxide column 22 corresponds to x Phase difference The width of the column corresponding to the distance r from the center of the metalens is calculated based on the relationship between and corresponds to the width a of the silicon oxide pillar 22 x Phase difference To design the metalens 100. Specifically, the phase difference at distance r is The width a of the silicon oxide columnar member 22 replaced by the phase difference x By setting in this way, the width a of the silicon oxide columnar object 22 corresponding to the distance r from the center of the super lens is obtained. x , so that the superlens 100 can be designed. Fig. 7A is an example of the pattern model of the designed metalens. Figure 7B yes Fig. 7AA magnified view of the vicinity of the center of the metalens. Figure 7C This is an enlarged view of the vicinity of the boundary where the width of the silicon oxide columnar material 22 of the super lens changes. x changes, and thus the phase difference Φ changes. Figure 7B The following is shown: In the center of the lens, the phase difference hardly changes with the location, so the width a x There is almost no change, and columns of roughly the same size are arranged in a two-dimensional periodic pattern. Figure 7C The folded part with a phase of 360° can be seen with a width a of 360°. x The width a of the folded 0 degree x At the border. Figure 7C In the folded front and back width a x Although they are quite different, the phases are continuously connected because the phases are 360° and 0°, which are folded.

[0107] (Calibration Step S31)

[0108] In the manufacturing method of the super lens 100 described later, after the silicon layer is formed into silicon pillars by electron beam lithography and silicon dry etching, the silicon pillars are oxidized. Due to oxidation, the silicon pillars expand, and the measured value of the oxidized silicon oxide pillars 22 deviates from the set value. Therefore, it is preferable to correct the set value of the silicon pillars before oxidation based on the measured value of the width of the silicon oxide pillars 22.

[0109] The calibration step S31 for calibrating the set value is described below. The calibration step S31 includes a columnar width measuring step S13 of manufacturing a super lens of silicon columns of a predetermined width, and measuring the width a of the silicon oxide columnar 22 of the obtained super lens. x ; a prediction function preparation step S14, after the width is measured, based on the set value of the width of the silicon oxide pillar 22 and the measured value of the width of the silicon oxide pillar 22, a prediction function is created to estimate the measured value of the silicon oxide pillar 22 corresponding to the design value of the silicon pillar before oxidation; and a feedback function preparation step S15, based on the obtained prediction function, a feedback function is created to calculate in a manner that the silicon oxide pillar 22 becomes the set value based on the measured value of the silicon oxide pillar 22, and the set value of the silicon pillar is corrected. The following is a description of each step.

[0110] (Column Width Measurement Process)

[0111] In the columnar width measuring step S13, a superlens is produced based on the design of silicon columns of a predetermined width, and the width a of the silicon oxide columns 22 of the obtained superlens is measured. x Width a xThe measurement can be performed based on an image observed using a scanning electron microscope, for example.

[0112] (Creation of prediction function)

[0113] In the prediction function preparation step S14, the width a of the columnar object 22 is x After the measurement step S13, a prediction function for estimating the measured value of the silicon pillar corresponding to the design value of the silicon pillar is created based on the original set value of the width of the silicon oxide pillar 22 and the measured value of the width of the silicon oxide pillar 22. The method for creating the prediction function is not particularly limited. For example, the prediction function can also be created by linearly approximating the ratio of the measured value to the set value of the silicon oxide pillar 22 (measured value / set value) and the set value of the width of the silicon oxide pillar 22.

[0114] (Creation of feedback function)

[0115] In the feedback function preparation step S15, based on the prediction function obtained in the prediction function preparation step S14, a feedback function is created that is calculated based on the measured value of the silicon oxide column 22 so as to become the set value of the silicon oxide column 22, and the set value of the silicon column is corrected. The feedback function is created by reversely solving the prediction function. The feedback function is a function that returns the width of the silicon column to the design value of the silicon column for the desired silicon oxide column 22. The feedback function is created to design and correct the initial width of the silicon column so that the silicon oxide column becomes the set value.

[0116] In the above content, the feedback function is obtained by making a super lens and measuring the width a of the silicon oxide columnar object 22 of the obtained super lens. x However, it is also possible to create silicon columns of various widths and shapes without creating a super lens, measure the width of the silicon oxide column obtained by oxidizing them, and find the deviation from the set value, thereby finding the feedback function. For making a super lens, it is ideal to also consider the influence of the surrounding during oxidation, but this is time-consuming. On the other hand, when only silicon columns are made, it is simple to grasp the expansion caused by oxidation.

[0117] According to the obtained feedback function, the silicon pillars are formed thinner than the set width at the stage of designing the width in consideration of the expansion due to oxidation, thereby reducing the influence of the deviation from the design value due to oxidation after the oxidation treatment.

[0118] The design method of the metalens 100 of the present disclosure has been described above. According to the design method of the metalens 100 of the present disclosure, the width of the columnar material of the metalens 100 can be controlled within a predetermined range, and the yield of the metalens 100 can be improved. In addition, the deviation from the design value caused by the influence of oxidation is corrected based on the measured value, so that the focusing characteristics can be further improved.

[0119] In the method for designing a metalens disclosed in the present invention, a prediction function and a feedback function are created, but a prediction function and a feedback function may not be created.

[0120] <Method for manufacturing superlens>

[0121] Next, a method for manufacturing the superlens 100 will be described. Figure 8 1 is a flowchart of a method for manufacturing the superlens 100 according to the first embodiment. Fig. 9 (a)~ Fig. 9 (c) means Figure 1 (a) and Figure 1 (b) is a cross-sectional view of an example of a manufacturing process of the manufacturing method of the super lens 100. The manufacturing method of the super lens of the first embodiment includes the following steps: a mask pattern forming step S20, forming a mask pattern 50 on the silicon layer 18 of the substrate 40 having the silicon layer 18 on the surface; an etching step S21, forming a silicon pattern layer 30 having an array pattern (silicon array pattern) 36 composed of a plurality of silicon pillars 32 by etching the silicon layer 18; and an oxidation treatment step S22, forming a pattern layer 20 composed of a plurality of silicon oxide pillars 22 by oxidizing at least a portion of the silicon in the silicon pattern layer 30.

[0122] (Mask Pattern Formation Step S20)

[0123] In the mask pattern forming step S20, a mask pattern 50 ( Fig. 9 (a)). The thickness and material of the mask pattern 50 are not particularly limited as long as they can form the silicon pattern layer 30 after etching. The mask pattern 50 can also be composed of resin, silicon oxide, silicon nitride or aluminum oxide. The method for forming the mask pattern 50 on the substrate 40 is not particularly limited. For example, in the case where the mask pattern 50 is composed of a resist, the mask pattern 50 can be formed by the method described below. The resist is applied to the substrate 40 and patterned by photolithography (electron beam lithography, deep ultraviolet lithography, nanoimprint lithography, etc.). After photolithography, the mask pattern 50 can be formed by development.

[0124] The mask pattern 50 can also be formed of a metal. Below, an example of a method for forming the mask pattern 50 when the mask pattern 50 is composed of a metal such as Cr is described. First, a metal such as Cr is deposited on the substrate 40 by evaporation or the like. Then, a resist (resin) is applied to the deposited metal. After the resist is applied, patterning is performed by photolithography. Then, the metal is etched to form the mask pattern 50. By using a metal that is more difficult to etch than the resist as the mask pattern 50, the surface 32a on the top side of the silicon column 32 can be prevented from being cut off during etching. As a result, the planar shape of the silicon column 32 can be processed more precisely, and the difference between the designed optical characteristics and the optical characteristics of the super lens 100 can be suppressed.

[0125] The substrate 40 is not particularly limited as long as it has a silicon layer 18 on the surface and can reflect incident light. In the first embodiment, the substrate 40 includes a supporting substrate 15, an intermediate layer 12 provided on the supporting substrate 15, and a silicon layer 18 provided on the intermediate layer 12. The material of the supporting substrate 15 is not particularly limited. For example, the material of the supporting substrate 15 is silicon. The material of the intermediate layer 12 is preferably a material whose etching rate is lower than that of Si during etching. As the material of the intermediate layer 12, for example, SiO 2 When the material of the intermediate layer 12 is SiO 2 When such a material has an etching rate lower than that of Si, etching at the intermediate layer 12 is suppressed, so that the height of the silicon pillar 32 is easily controlled. The thickness of the supporting substrate 15 is not particularly limited as long as it can function as a reflective super lens 100. The thickness of the intermediate layer 12 is not particularly limited as long as it can function as a reflective super lens 100. The thickness of the intermediate layer 12 is, for example, 1 μm to 20 μm. The substrate 40 is, for example, a silicon on insulator (SOI) substrate.

[0126] The crystallinity of the silicon layer 18 is not particularly limited. The silicon layer 18 may be single crystal, polycrystalline, or amorphous. The silicon layer 18 is preferably single crystal.

[0127] The thickness of the silicon layer 18 can be appropriately set according to the design of the superlens 100. For example, if the mask pattern 50 does not disappear during the etching process, the thickness of the silicon layer 18 is the height H of the silicon oxide pillars 22. For example, the thickness of the silicon layer 18 is 1.0 μm to 3.0 μm.

[0128] (Etching Step S21)

[0129] In the etching step S21, the silicon layer 18 is etched to form a silicon pattern layer 30 having an array pattern 36 composed of a plurality of silicon pillars 32 ( Fig. 9(b)). In the etching process S21, the silicon pattern layer 30 may also be etched in consideration of the expansion of silicon in the oxidation process S22. The etching selectivity of Si is high, so a silicon column 32 with a high aspect ratio can be formed. The etching is preferably dry etching. The dry etching can be performed by a known method, such as inductively coupled plasma etching. Preferably, during the etching, a passivation step for forming a barrier layer and an etching step for etching silicon are alternately performed. By setting it this way, a silicon column 32 with a high aspect ratio can be formed. When etching silicon, based on the design value of the silicon column 32 obtained according to the feedback function, the silicon column 32 is formed with a width of the design value. Usually, it is formed to be thinner than the set value in consideration of the expansion during the oxidation process.

[0130] Preferably, the center-to-center distance Λ in the X direction between the silicon pillars 32 formed in the etching step S21 is x 1 is the width a of the silicon pillar 32 x1 A more preferred center-to-center distance Λ between the silicon pillars 32 in the X direction is x1 is the width a of the silicon pillar 32 x1 When the silicon pillar 32 is completely oxidized, the width of the silicon pillar 32 becomes, for example, 1.4 to 1.6 times. Therefore, by making the center-to-center distance Λ in the X direction x 1 is 1.4 to 1.6 times, which can prevent the silicon oxide pillars 22 from being connected to each other. Preferably, the center-to-center distance Λ between the silicon pillars 32 in the Y direction is y1 The same is true for the width a of the silicon pillar 32 in the Y direction. y1 A more preferred center-to-center distance Λ between the silicon pillars 32 in the Y direction is y1 is the width a of the silicon pillar 32 y1 More than 1.6 times of .

[0131] (Oxidation Treatment Step S22)

[0132] In the oxidation treatment step S22, after removing the mask pattern 50, at least a portion of the silicon in the silicon pattern layer 30 is oxidized, thereby forming a pattern layer 20 ( Fig. 9 (c)). Since the feedback function has been taken into account, the silicon oxide columnar material 22 formed becomes a value close to the set value. The pattern layer 20 composed of the silicon oxide columnar material 22 has a focus corresponding to the light incident on the pattern layer 20. By oxidizing the silicon columnar material 32 to form the silicon oxide columnar material 22, a high aspect ratio SiO can be formed in a non-destructive manner. 2The method of oxidizing silicon is not particularly limited. As the oxidation method, thermal oxidation is preferred. As the thermal oxidation method, dry oxidation, wet oxidation, steam oxidation, etc. can be cited. Dry oxidation and wet oxidation are preferred. Wet oxidation is particularly preferred. By oxidizing the silicon columnar material 32 by wet oxidation, the silicon oxide columnar material 22 can be formed in a short time.

[0133] The temperature during oxidation is not particularly limited, and is, for example, 800° C. to 1150° C. The time for oxidizing the silicon pattern layer 30 can be set appropriately. Alternatively, all silicon in the silicon pattern layer 30 may be SiO 2 By making all silicon in the silicon pattern layer 30 SiO 2 , which can improve the transmittance of the pattern layer 20.

[0134] The above is a description of the method for manufacturing the superlens of the present embodiment. According to the method for manufacturing the superlens of the first embodiment, a SiO 2 Therefore, it is possible to manufacture a metalens 100 having a short focal length.

[0135] In the method for manufacturing the superlens of the first embodiment, the following step may be included after the etching step S21: annealing the substrate having the silicon pattern layer 30 in a hydrogen atmosphere, an argon atmosphere, or a mixed atmosphere of hydrogen and argon. By performing hydrogen annealing, argon annealing, or annealing in a mixed gas of hydrogen and argon after the etching step S21, it is possible to reduce the unevenness of the side surface of the silicon pillar 32. The hydrogen annealing, argon annealing, or annealing in a mixed gas of hydrogen and argon can be performed, for example, at a temperature of 800° C. to 1200° C. in an atmosphere of 100% hydrogen, 100% argon, or a mixed atmosphere of hydrogen and argon.

[0136] <Second Embodiment>

[0137] The supporting substrate 15 of the super lens of the first embodiment may be a transparent substrate (for example, silicon dioxide (SiO 2 )). Thus, the superlens 100 of the second embodiment can be used as a transmissive superlens that transmits incident light.

[0138] It should be noted that, at this time, the intermediate layer 12 may be transparent, or there may be no intermediate layer 12 .

[0139] During manufacturing, the supporting substrate 15 can be made of transparent SiO 2 That's it.

[0140] The superlens 100 according to the second embodiment may have warp.

[0141] <Third Embodiment>

[0142] Hereinafter, a superlens according to a third embodiment of the invention will be described. Fig.10 (a) is a plan view in which a part of the array pattern of the superlens 100C according to the third embodiment is enlarged. Fig.10 (b) is Fig.10 (a) is a cross-sectional view of a superlens 100C along line CC. The superlens 100C includes, in order: a supporting substrate 15; and a pattern layer 20C having an array pattern 26C composed of a plurality of holes 24. The superlens 100C of the third embodiment is a reflective superlens that reflects incident light.

[0143] (Pattern layer 20C)

[0144] In the third embodiment, the pattern layer 20C is provided on the intermediate layer 12. The pattern layer 20C has an array pattern 26C composed of a plurality of holes 24. Here, the array pattern 26C is a pattern in which microstructures (holes 24 in the case of the third embodiment) are regularly arranged in the X direction and the Y direction at a predetermined interval. The pattern layer 20C contains at least SiO 2 The pattern layer 20C may also contain Si.

[0145] The shape (planar shape) of the hole 24 viewed from the Z direction is not particularly limited, and may be a polygon, a circle, or the like. In the third embodiment, the planar shape of the hole 24 is a square. The width a of the hole 24 in the X direction is xc and the width a in the Y direction yc The width a of the hole 24 in the X direction is appropriately set according to the design of the super lens 100C. xc For example, it is 150 nm to 600 nm. The width a of the hole 24 in the Y direction is yc For example, it is 150nm to 600nm.

[0146] The center-to-center distance (period) of the holes 24 along the X direction as viewed from the Z direction is Λ xc The center distance (period) between the holes 24 along the Y direction is Λ yc The period Λ of the holes 24 along the X direction is appropriately set according to the design of the super lens 100C. xc For example, it is 200 nm to 600 nm. The period Λ of the holes 24 along the Y direction yc For example, it is 200nm to 600nm. Preferably, the period Λ xc With period Λ yc It should be noted that the center of the hole 24 observed from the Z direction is the center of the smallest containing circle when the planar shape (outer shape) of the hole 24 is a polygon, and is the center of the circle when the planar shape of the hole 24 is a circle.

[0147] The length (depth) Hc of the hole 24 in the Z direction is appropriately set according to the design of the superlens 100C. The depth Hc of the hole 24 is 1.0 μm to 3.0 μm.

[0148] The depth Hc of the hole 24 and the width a of the hole 24 in the X direction are xc The aspect ratio (Hc / a xc ) is appropriately set according to the design of the superlens 100C. xc ) is greater than 6.7. A more preferred aspect ratio (Hc / a xc ) is greater than 7.0. Similarly, the depth Hc of the hole 24 and the width a of the hole 24 in the Y direction are yc The aspect ratio (Hc / a yc The maximum value of ) is also appropriately set according to the design of the superlens 100C. yc ) is greater than 6.7. A more preferred aspect ratio (Hc / a yc ) is greater than 7.0. When the planar shape of the hole 24 is a square or a circle, the aspect ratio (Hc / a xc ) and aspect ratio (Hc / a yc That is, in this case, the aspect ratio of the hole 24 is the ratio of the width to the depth.

[0149] As described above, the superlens 100C of the present embodiment has been described. Since the aspect ratio of the hole 24 of the superlens 100c is high, the focal length can be shortened to 500 μm to 2500 μm.

[0150] The superlens 100C is a reflective type, but if a transmissive substrate is used as the substrate, the superlens 100C can become a transmissive type superlens.

[0151] In the third embodiment, the super lens 100C includes the intermediate layer 12 , but the intermediate layer 12 may not be included as long as the incident light can be reflected.

[0152] The superlens 100C according to the third embodiment may have warp.

[0153] The manufacturing method of the superlens 100C of the third embodiment is the same as that of the first embodiment, except that the holes 24 with a high aspect ratio are formed by covering the locations other than the holes 24 with a mask pattern and etching.

[0154] <First Modification>

[0155] As a modification of the super lens of the first embodiment, the shape (planar shape) of the silicon oxide columnar member 22 may be circular. Even if the shape of the silicon oxide columnar member 22 is circular, by adjusting the occupancy ratio f x etc., and can also function as a super lens.

[0156] The above is a detailed description of the metalens of the present embodiment, the design method of the metalens, and the manufacturing method of the metalens. It should be noted that the technical scope of the present invention is not limited to the embodiments, and various changes can be made without departing from the main purpose of the present invention. In addition, without departing from the main purpose of the present invention, the constituent elements in the embodiments can be appropriately replaced with well-known constituent elements, and the modifications can also be appropriately combined. In addition, the metalens of the present embodiment can also be mounted on an electronic device. As an electronic device equipped with the metalens of the present embodiment, for example, a mobile phone can be cited.

[0157] Example

[0158] Next, an embodiment of the present invention is described, but the conditions in the embodiment are a conditional example adopted to confirm the feasibility and effect of the present invention, and the present invention is not limited to this conditional example. The present invention can adopt various conditions as long as the purpose of the present invention is achieved without departing from the main purpose of the present invention.

[0159] (Example 1)

[0160] The focal length is set to 1000 μm, and the wavelength is set to 532 nm. The super lens 100 is designed by the method described in the above-mentioned method for designing the super lens 100. The height H of the column is set to 2.5 μm, the period of the column is set to 400 nm, and the width of the column is set to 192 nm to 340 nm so that the phase difference is in the range of 0° to 360°. Figure 5 The phase difference and the distance r from the center of the lens determine the width of the column at each position, and the design is as follows Fig. 7A It should be noted that the superlens of the embodiment is not made in the shape of a quadrangular prism, but in the shape of a cylinder.

[0161] (Manufacturing of Reflective Super Lens)

[0162] A 20 mm square SOI substrate was used. The thickness of the treatment layer (Si) was set to 525 μm, the crystal orientation was (111), and the box layer (SiO 2) was set to 4 μm in thickness and the crystal orientation of the device layer (Si) was (111). Electron beam (EB: Electron Beam) resist (ZEP520A, manufactured by ZEON Corporation, Japan) and anti-charge agent for electron line drawing (ESPACER) were formed on the device Si surface by spin coating. The resist film thickness was about 140 nm.

[0163] EB drawing was performed using an EB drawing apparatus JBX-6300SK manufactured by JEOL Ltd. After EB drawing, development was performed. Pure water was used to rinse the anti-charge agent for electron line drawing, ZED-N50 manufactured by ZEON Corporation of Japan was used as the developer of the resist, and isopropyl alcohol (IPA) was used to rinse the developer.

[0164] For dry etching, an inductively coupled plasma (ICP: Inductively Coupled Plasma) etching apparatus MUC-21 manufactured by SPP Technologies Co., Ltd. was used. 4 F 8 After 2.5 seconds of gas passivation, the SF 6 The gas etching was repeated for 3 seconds as one cycle, and the etching was repeated 20 times to form Si pillars.

[0165] After etching, ultrasonic cleaning was performed with acetone for 15 minutes, and then rinsed with IPA, and dried on a hot plate at 110° C. for 15 minutes.

[0166] The substrate on which the Si pillars were formed was wet oxidized using a thermal oxidation furnace. The oxidation temperature was set to 1100° C. to produce a superlens. The oxidation was performed under two conditions: 1 hour and 3 hours.

[0167] (Expansion rate of column width)

[0168] The silicon pillars before oxidation and the silicon oxide pillars after oxidation were observed using a scanning electron microscope (SEM) SU-70 manufactured by Hitachi High-Tech Corporation, and the expansion rate of the width of the pillars was confirmed. Fig.11 The relationship between the width (nm) of the obtained silicon pillars and the expansion rate of the width of the pillars after oxidation is shown. Fig.11 The horizontal axis represents the width (nm) of the silicon column (measured value of the Si column), and the vertical axis represents the expansion rate of the width (column width) of the column (width after oxidation / width before oxidation).

[0169] like Fig.11 As shown, the expansion rate shows a tendency to increase according to the column width. At 200 nm to 280 nm, the expansion rate of the columnar width is 1.4 to 1.6 times.

[0170] (Evaluation of focal length)

[0171] A schematic diagram of the focal length evaluation device is shown in Fig.12 . The solid line represents the irradiation light path emitted from the light source 51, and the dotted line represents the light path observed by the camera 52. The irradiation light is irradiated to the super lens in a manner that does not form an image on the super lens surface but becomes parallel light. The camera 52 can confirm the image on the surface of the irradiated super lens 100. The amount of light emitted from the light source 51 is reduced by the aperture stop 53. After the light from the light source changes its direction toward the super lens 100 side through the semi-transparent and semi-reflective mirror 54, it is focused on the surface of the super lens 100 by the focusing lens 55. The image on the surface of the super lens 100 becomes parallel light through the objective lens 55, and is formed toward the camera 52 via the lens 56. In this way, the focal length can be evaluated.

[0172] First, place the sample (superlens) on the workbench and focus on the surface of the device layer. Set the sample to the benchmark of the workbench height of 0μm. Next, in order to make the outline of the aperture image as clear as possible, reduce the aperture aperture to the maximum extent. Repeatedly shoot while confirming the height with a micrometer while lowering the workbench. The captured image is evaluated using image processing software. The evaluation performed is a brightness distribution evaluation, which analyzes the brightness distribution corresponding to the distance from the center of the lens based on the captured image. The brightness value is calculated based on the RGB value of the obtained image data using the following (7) formula. It should be noted that RGB refers to R (red component), G (green component), and B (blue component).

[0173] [Formula 3]

[0174]

[0175] The relationship between the distance r from the center of the lens and the brightness when the height of the metalens oxidized for 1 hour was changed is shown in FIG. Fig.13 . Fig.13 The value of Z recorded in each graph in represents the distance (μm) by which the stage is lowered. Fig.13 (a) shows the relationship between the distance r from the lens center and the brightness in the range of Z=0 μm to Z=500 μm. Fig.13 In (a), the horizontal axis represents the distance r from the center of the lens, and the vertical axis represents the brightness. Fig.13 (b) shows the relationship between the distance r from the lens center and the brightness when Z=600 μm. Fig.13 In (b), the horizontal axis represents the distance r from the lens center, and the vertical axis represents the brightness. Fig.13 (c) shows the relationship between the distance r from the lens center and the brightness in the range of Z=700 μm to Z=1400 μm. Fig.13The horizontal axis of (c) represents the distance r from the center of the lens, and the vertical axis represents the brightness. In the metalens oxidized for 1 hour, the highest brightness is reached at Z = 500 μm. The bottom edge of the brightness distribution at Z = 600 μm becomes wider, and the brightness decreases from Z = 700 μm to Z = 1400 μm.

[0176] The relationship between the distance r from the center of the lens and the brightness measured by changing the height of the metalens oxidized for 3 hours is shown in FIG. Fig.14 . Fig.14 The value of Z recorded in each graph in represents the distance (μm) by which the stage is lowered. Fig.14 (a) shows the relationship between the distance r from the lens center and the brightness in the range of Z=0 μm to Z=500 μm. Fig.14 In (a), the horizontal axis represents the distance r from the center of the lens, and the vertical axis represents the brightness. Fig.14 (b) shows the relationship between the distance r from the lens center and the brightness when Z=600 μm. Fig.14 In (b), the horizontal axis represents the distance r from the lens center, and the vertical axis represents the brightness. Fig.14 (c) shows the relationship between the distance r from the lens center and the brightness in the range of Z=700 μm to Z=1400 μm. Fig.14 The horizontal axis of (c) represents the distance r from the center of the lens, and the vertical axis represents the brightness. In the superlens oxidized for 3 hours, the highest brightness is reached at Z = 500 μm. The bottom edge of the brightness distribution at Z = 600 μm becomes wider, and the brightness decreases from Z = 700 μm to Z = 1400 μm. In terms of brightness, the brightness increases after oxidizing for 3 hours. It is speculated that this is due to the SiO 2 The increase in the ratio and the change in phase caused by the size expansion due to oxidation are manifested as changes in brightness. The actual height of the columnar material obtained is 1521nm, and the width of the silicon oxide columnar material is 200nm to 350nm. It is confirmed that a high aspect ratio columnar material with an aspect ratio (height / width) of 4.3 to 7.6 can be formed in the superlens oxidized for 3 hours.

[0177] (Example 2)

[0178] Next, the deviation between the measured value and the designed value of the width of the silicon oxide column of the obtained super lens is corrected, and the super lens is produced again. The correction is performed in the following order. First, the width of the silicon oxide column of the super lens is measured by SEM. Next, based on the ratio of the measured value of the width of the obtained silicon oxide column to the set value and the designed value of the column, an approximate formula of the following formula (8) is created by linear approximation. Fig.15 The measured value W of the width of the silicon oxide column is shown in mp With the set value W d The ratio of the column to the design value W d The result obtained by linear approximation. Fig.15 The horizontal axis is the width of the column (nm), and the vertical axis is the ratio of the measured value of the width of the column to the designed value of the width (measured value W mp / Design value W d ). Multiply both sides of the obtained equation (8) by the set value W of the columnar width. d , we get equation (9) as the prediction function. By reversing equation (9), we get equation (10) as the feedback function. d is the setting value before calibration, W df Based on this correction, the width of each silicon oxide columnar material is corrected.

[0179] Next, the metalens of Example 2 is produced based on the corrected design by the same creation method as that of Example 1. It should be noted that the metalens produced in Example 2 is refracted once in the pattern layer 20, passes through the intermediate layer (SiO 2 The light is reflected at the interface between the intermediate layer 12 and the supporting substrate 15, and is refracted again at the pattern layer 20. Therefore, the lens formed by synthesizing two lenses is designed according to the focal length after synthesis (reflection focal length). In Example 2, the reflection focal length is set to 835 μm.

[0180] [Formula 4]

[0181] γ=0.0027W d +0.2816…(8)

[0182] W mp =0.0027W d 2 +0.2816W d …(9)

[0183]

[0184] (Evaluation of focal length)

[0185] The results of color mapping the brightness measurement results of the metalens of Example 2 are shown in FIG. Fig.16 At a height of Z = 700 μm-1100 μm, light is focused near the center and high brightness is obtained ( Fig.16). Here, it can be seen that the produced superlens layer functions as a focusing element. The overall brightness is also high. Although the figure is omitted, the brightness of each height position at r = 0.101μm near the center was investigated, and as a result, the highest brightness was obtained at Z = 1000μm, and its value was the highest value 245. The strongest focusing occurred at this position, and the focal length of the produced reflective superlens became fREF = 1000μm. According to the results, the superlens obtained according to the superlens and the method for manufacturing the superlens of the present invention can be widely used in electronic devices (including mechanical ones, etc.) using lenses, such as smartphones, VR glasses, microscopes, cameras, etc.

[0186] As described above, through the experiments of the examples, the embodiments of the present invention can provide a metalens with a short focal length and a method for manufacturing a metalens. In particular, it is confirmed that the embodiments of the present invention can take advantage of the excellent etching selectivity of Si and the ability to heat-oxidize SiO2. 2 Special effect of chemistry.

[0187] The above describes the metalens, the method for manufacturing the metalens, the electronic device, and the method for designing the metalens according to the present embodiment. The metalens according to the present embodiment can shorten the focal length. In addition, according to the method for manufacturing the metalens and the method for designing the metalens according to the present embodiment, a metalens with a short focal length can be obtained.

[0188] Industrial Applicability

[0189] The metalens disclosed in the present invention has a short focal length and therefore has high industrial applicability.

[0190] Description of Reference Numerals

[0191] 12: intermediate layer; 15: supporting substrate; 20: pattern layer; 22: silicon oxide pillars; 24: holes; 100: super lens.

Claims

1. A method for manufacturing a metalens, comprising the following steps: A mask pattern forming step of forming a mask pattern on the silicon layer of a substrate having a silicon layer on its surface; An etching step of etching the silicon layer to form a silicon pattern layer having an array pattern consisting of a plurality of silicon pillars or a plurality of pre-oxidation holes; as well as an oxidation treatment step of oxidizing at least a portion of the silicon in the silicon pattern layer to form a pattern layer consisting of a plurality of silicon oxide pillars or a plurality of holes; The pattern layer has a focal point corresponding to light incident on the pattern layer.

2. The method for manufacturing a superlens according to claim 1, in, The oxidation is wet oxidation or dry oxidation.

3. The method for manufacturing a superlens according to claim 1 or 2, in, After the etching process, the following process is also included: The substrate having the silicon pattern layer is annealed in a hydrogen atmosphere, an argon atmosphere or a mixed atmosphere of hydrogen and argon.

4. The method for manufacturing a metalens according to claim 1 or 2, in, The mask pattern is made of resin, silicon oxide, silicon nitride or aluminum oxide.

5. The method for manufacturing a superlens according to claim 1 or 2, in, The mask pattern is made of metal.

6. The method for manufacturing a superlens according to claim 1 or 2, in, The maximum value of the aspect ratio of the silicon oxide pillars or the holes in the pattern layer is greater than 6.

7.

7. The method for manufacturing a superlens according to claim 1 or 2, in, The center-to-center distance between the silicon pillars is greater than 1.4 times the width of the silicon pillars.

8. The method for manufacturing a superlens according to claim 1 or 2, in, In the etching process, the silicon pattern layer is etched in consideration of expansion of silicon in the oxidation process.

9. A metalens comprising: a support substrate; and The pattern layer has an array pattern consisting of a plurality of silicon oxide pillars or a plurality of holes, The maximum aspect ratio of the silicon oxide pillars or the holes in the pattern layer is greater than 6.7, The pattern layer contains at least SiO 2 .

10. The metalens according to claim 9, in, The pattern layer is made of SiO 2 constitute.

11. The metalens according to claim 9 or 10, in, An intermediate layer is further provided between the support substrate and the pattern layer.

12. The metalens according to claim 9 or 10, in, The pattern layer includes a folded portion at a location having a phase difference of 360° with respect to a center.

13. An electronic device equipped with the superlens according to claim 9 or 10.

14. A method for designing a metalens, comprising the following steps: The phase difference calculation step calculates the phase difference corresponding to the distance r from the center of the metalens based on the wavelength λ of the incident light and the focal length f. The columnar size determination step calculates the height H and width a of the silicon oxide column constituting the super lens. x and period Λ x and corresponds to the width a x Phase difference The relationship between the height H and the width a is determined x The range and period Λ x ;as well as A columnar width calculation step corresponding to the distance r, after the columnar size determination step, according to the phase difference corresponding to the distance r and corresponds to the width a x Phase difference , the width a corresponding to the distance r from the center of the metalens is calculated x , In the phase difference calculation step, the phase difference corresponding to the distance r When the angle is 360° or more, the following formula (A) and formula (B) are satisfied to calculate the angle. in, In the above formula (A), n is a natural number.

15. The method for manufacturing a superlens according to claim 1 or 2, in, The method further comprises the step of performing the method for designing a superlens according to claim 14.

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