Metasurface unit with depth continuously and gradually changed

Abstract

The utility model provides a depth continuous gradual change metasurface unit, which comprises at least one functional area, a plurality of depth continuous gradual change metasurface subunits are arranged in the functional area, the structures of the metasurface subunits can be the same or different, each metasurface subunit comprises a plurality of concentric rings, and the concentric rings are arranged in the functional area. The diameters of the concentric rings are different, and the line widths and the distances can be completely the same or partially different, so that different parameters of the metasurface subunits are modulated, and more choices are provided for the design of the metasurface structure in the field; the optical performance of an optical product is more excellent through the metasurface subunit structures which are different in depth and are continuously and gradually changed, and more optical metasurface unit structure selections are provided for technicians in the field.

Description

Technical Field

[0001] The utility model relates to the field of semiconductor technology, in particular to a deep continuous gradient metasurface unit and method. Background Art

[0002] Due to the ability of the metasurface structure to precisely control the characteristics of light waves such as amplitude, phase, polarization, and frequency in a two-dimensional plane, the design and application of this material are rapidly developing in multiple fields, such as imaging and virtual reality technologies, optical sensing, communication technologies, and other fields. Due to its ability to achieve high-resolution imaging and holographic display, the metasurface structure can provide thinner and more efficient near-eye display technology in augmented reality and virtual reality devices; or it can be used as an achromatic superlens, etc., to achieve high-quality imaging, and has application value in multiple cutting-edge technology fields.

[0003] With the progress of material science and nanofabrication technology, it is expected that metasurfaces will play an even more important role in future optical and optoelectronic fields. Based on the rapid development and broad application prospects of current metasurface technology, it has become the focus of industry research; however, there are still some huge challenges, including the complexity of manufacturing processes, dispersion problems, and limitations in dynamic modulation capabilities, making the preparation process of metasurfaces difficult. Therefore, how to prepare a metasurface unit structure with multiple structures and deep continuous gradients to meet different technical requirements and achieve multi-parameter modulation of metasurface units is important for those skilled in the art. Summary of the Utility Model

[0004] The utility model intends to provide a deep continuous gradient metasurface unit and method, providing a metasurface unit with multiple structures and deep continuous gradients and its related preparation process method to achieve multi-parameter modulation of metasurface units, improve the existing metasurface preparation process, provide more structural and process options for those skilled in the art, and increase the applicable range of metasurface structures.

[0005] The utility model provides a deep continuous gradient metasurface unit, which is characterized in that it at least includes a first material layer, and any surface of the first material layer includes at least one functional area, and a number of deep continuous gradient metasurface sub-units are included in the functional area.

[0006] Exemplarily, it includes 2 functional areas, 3 functional areas, and so on.

[0007] Further, in some embodiments, each of the metasurface sub-units includes a number of concentric rings.

[0008] Further, in some embodiments, it further includes a second material layer, and the second material layer is formed on the surface of the first material layer away from the functional area.

[0009] Furthermore, in some embodiments, each of the metasurface subunits includes a plurality of concentric rings, and the diameters of each of the concentric rings are different.

[0010] Furthermore, in some embodiments, the line width of each of the rings is the same; or the line widths of at least two of the rings are different.

[0011] Furthermore, in some embodiments, the spacing between at least two of the rings is the same, and the spacing is the distance between adjacent rings.

[0012] Furthermore, in some embodiments, the spacings between at least two of the rings are different, and the spacing is the distance between adjacent rings.

[0013] Furthermore, in some embodiments, the structural dimensions of the metasurface subunit range from 0.5 mm to 6 mm; the diameter range of any one of the concentric rings is from 50 nm to 6 mm.

[0014] Furthermore, in some embodiments, the line width range of any one of the concentric rings is from 20 to 200 nm; the spacing range between adjacent concentric rings is from 50 nm to 150 nm.

[0015] The depth variation range of the depth continuously varying metasurface subunit in the metasurface unit is from 20 nm to 80 nm.

[0016] The present utility model provides a depth continuously varying metasurface unit. The metasurface unit has depth continuously varying metasurface subunits composed of a plurality of concentric rings. The structures of each metasurface subunit can be the same or different. The diameters of each of the concentric rings are different, and the line widths and distances can be the same or different, so as to modulate different parameters of the metasurface subunits, providing more choices for the design of metasurface structures in the art.

[0017] In addition, the optical products of the present application have more excellent optical performance to meet more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a schematic structural diagram of a depth continuously varying metasurface unit provided by the present utility model;

[0020] Figure 2Schematic diagram of the structure of a metasurface subunit of a deep continuous gradient metasurface unit provided by the present utility model;

[0021] Figure 3 Schematic diagram of the structure of a metasurface unit formed by etching a deep continuous gradient metasurface unit using the etching process provided in the prior art;

[0022] Figure 4 Schematic diagram of the structural change of a method for preparing a deep continuous gradient metasurface unit provided by the present utility model;

[0023] Figure 5 In the present utility model Figure 4 Partial enlarged schematic diagram of the structural diagram of the functional area;

[0024] Figure 6 Top view of the metasurface subunit structure provided by the present utility model. Specific embodiments

[0025] In order to enable those skilled in the art to better understand the solution of the present utility model, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0026] It should be noted that the terms "first", "second", etc. in the description and claims of the present utility model and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances, so that the embodiments of the present utility model described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] The present utility model provides a deep continuous gradient metasurface unit 100, as shown in the left figure in Figure 1 which at least includes a first material layer 10. Any surface of the first material layer 10 includes at least one functional area, as shown by the dotted line in Figure 1 and the functional area includes several metasurface subunits with continuous depth gradients.

[0028] Exemplarily, it includes 2 functional regions, 3 functional regions, and so on. Those skilled in the art can select the number of functional regions according to different technical requirements, etc., all of which are within the protection scope of this application. The structures of the metasurface subunits within each functional region can be different or the same. The so-called different structures refer to different structural dimensions.

[0029] In some embodiments, each metasurface subunit includes a plurality of concentric rings.

[0030] There are at least two metasurface subunits with continuously varying depths within the functional region.

[0031] The continuously varying depth defined by the present utility model means that within the functional region, the depths of several metasurface subunits show continuous changes, such as continuously increasing depth, or continuously decreasing depth, or overlapping settings of two different depths, etc. For example, the gradient range of the depth change difference is in the range of (2% - 5%). And within the functional region, there are multiple metasurface subunits with different depths.

[0032] Furthermore, as Figure 1 shown in the right figure in

[0033] it also includes a second material layer 20, and the second material layer 20 is formed on the surface of the first material layer 20 away from the functional region.

[0034] In some other embodiments, as Figure 2 shown, each metasurface subunit includes a plurality of concentric rings, the diameters of each ring are different, and the line widths of each ring can be the same or different. Further, the distances between adjacent rings can be the same or different. The structures of each metasurface subunit can be the same or different, and appropriate adjustments are made based on different scenario requirements.

[0035] Specifically, as Figure 6 shown, a top view schematic diagram of a metasurface subunit structure is shown. Based on different metasurface structure designs, the range of the structural dimensions of the metasurface subunit is limited to 0.5 mm - 6 mm, that is, it is equivalent to the diameter D of the largest ring of the structural dimension, and the range of the diameter D of the largest ring is 0.5 mm - 6 mm; the range of the diameter d of any concentric ring is 50 nm - 6 mm; the range of the line width W of each concentric ring is 20 - 200 nm (the line width W refers to the edge width size of the concentric ring); the range of the distance L between adjacent concentric rings is 50 nm - 150 nm; the range of the height of any concentric ring is 50 - 450 nm; to achieve the modulation of different metasurface structures and improve the degree of freedom of regulation.

[0036] As Figure 2 、 Figure 6It shows that the diameters d of the multiple concentric rings are different, ranging from 50nm to 6mm, the line widths of adjacent rings are the same or different, the line width W ranges from 20 to 200nm, and the distances L between adjacent rings can be the same or different, ranging from 50nm to 150nm; of course Figure 2 and Figure 6 It is only an example of several concentric rings of a metasurface subunit, and does not represent the number of concentric rings of a specific metasurface structure. Based on different design requirements, it can be limited to include multiple different concentric ring structures. The deep continuous gradient functional area composed of several metasurface subunits can solve the complexity of the manufacturing process of the metasurface unit, dispersion problems, and dynamic control capabilities through the modulation of various process and performance parameters.

[0037] Further, optionally, the depth variation range of the continuous depth gradient supersurface sub-unit in the supersurface unit 100 is 20 nm to 80 nm.

[0038] The utility model limits the structure of each metasurface subunit, and each metasurface subunit is composed of a number of concentric circular rings. By modulating the diameter, line width, distance and other parameters of each circular ring, the diameter of each circular ring, the line width of each circular ring, and the spacing between adjacent circular rings can be partially the same or completely different, thereby modulating the amplitude, phase and frequency response of different wavelengths to achieve specific phase delay, regulate polarization state and other effects, thereby increasing the design freedom of the metasurface structure.

[0039] Specifically, the line width of each ring is the same; or the line width of at least two rings is different; the spacing between the rings is the same; or the spacing between at least two rings is different, and the spacing is the distance between adjacent rings. For example, if there are multiple rings, the spacing between each ring can be the same, or the spacing between each ring can be partially the same or completely different; for example, if there are 6 concentric rings, such as Figure 6 As shown, the spacing L between each ring can be partially the same or completely different to achieve modulation of different spacings. The line width W of the concentric rings can also be partially the same or completely different.

[0040] Furthermore, in order to obtain a depth-continuous gradient metasurface unit 100 of the above embodiment, if a conventional etching process in the prior art is used, the desired etching depth cannot be achieved, and the following problems often occur: Figure 3 The over-etching phenomenon in the process is likely to cause an over-etching depth on the surface of the second material layer 20. In order to improve this phenomenon, the utility model proposes a method for preparing a depth-continuous gradient supersurface unit.

[0041] In more detail, a method for preparing a deep continuous gradient super surface unit as described in the above embodiment can be referred to Figure 4 , including the following steps:

[0042] (1) Provide at least a first material layer 10 and a second material layer 20, and the first material layer 10 is formed on any one side surface of the second material layer 20;

[0043] (2) Form at least one functional region on the surface of the first material layer 10 away from the second material layer 20, and the depth of the functional region changes continuously and gradually;

[0044] (3) Deposit a photoresist in the functional region and perform surface planarization on it;

[0045] (4) Pattern the photoresist to form a patterned region;

[0046] (5) Etch the first material layer 10, expose and develop it to obtain a metasurface unit with a continuously and gradually changing depth.

[0047] Specifically, in step (1), the second material layer 20 serves as an etching substrate material, and materials such as Si, SiO2, TiO2, SiC, LiNbO3, germanium, gallium arsenide, etc. can be selected as the substrate; the first material layer 10 is deposited and formed on any surface of the second material layer 20, and materials such as SiO2, TiO2, SiC, LiNbO3, etc. can be selected for the first material layer. The thicknesses of the first material layer 10 and the second material layer 20 are in the range of 10 - 200 nm.

[0048] In step (2), specifically, it further includes: first calculating the etching depth of the first material layer at different region positions in at least one functional region, and performing depth-gradual etching on the first material layer; thereby obtaining a functional region with a continuously and gradually changing depth.

[0049] Specifically, in a certain functional region, the etching depth H1 of the first material layer at a certain place can be determined by the following formula:

[0050] H1 = H - [T - (H1 / V1)] * [V1 / K] (1)

[0051] In formula (1), H1 represents the etching depth of the first material layer at a certain place; H represents the target depth; T represents the total etching time, including the etching time of the first material layer and the etching time of the second material layer; V1 represents the etching rate of etching the first material layer, and the range is 0.5 - 3 nm / s; K represents the etching selectivity ratio of the second material layer to the first material layer, and the range is 4 - 9;

[0052] For further illustration, as Figure 5 shown, it is Figure 4The enlarged view of the local structure in step 2. Assuming the etching depth H1 of the first material layer at a certain position, the gradient etching depth of the depth continuously varying functional region at a certain position can be determined by formula (1). From this, the gradient etching depths at different positions can be determined, and a series of different etching depths of the first material layer can be obtained, such as H 11 、H 12 、H 13 ...... and several other different etching depths. Based on this, a functional region with continuously varying depth can be formed through the etching process. Of course, Figures 1 to 5 only shows the case including one functional region in []. For those skilled in the art, there are also cases including two functional regions, three functional regions, and other multiple functional regions. The present utility model does not make a quantitative limitation on this.

[0053] In this step, by etching different depths at different functional regions or different positions of the functional region, in the present utility model, by limiting the time of the first material layer exposed to the gas ion cluster beam and controlling the moving speed of the first material layer, etching at different depth positions within different functional regions can be achieved, obtaining a continuously varying functional region as shown in step (2) of []. Figure 4 in [].

[0054] Furthermore, in step (2), based on the etching selectivity between the first material layer and the second material layer, the present utility model inversely deduces and calculates the etching depths of the first material layer with continuously varying depth at different positions, thereby realizing the modulation of the continuous depth variation, which is important for the preparation of the continuously varying depth metasurface unit of the present utility model and is substantially different from the prior art.

[0055] More specifically, for the first material layer and the second material layer, the etching depths of different functional regions are calculated based on formula (1), as shown in Table 1 below:

[0056]

[0057] In the table, T1 represents the etching time of the first material layer; T2 represents the etching time of the second material layer; T represents the total etching time; V1 represents the etching rate of the first material layer; V2 represents the etching rate of the second material layer; H represents the total depth change.

[0058] From formula (1): H1 = H - [T - (H1 / V1)] * [V1 / K], after transformation, it is obtained that H1 = (KH - TV1) / (K - 1); H1 represents the etching depth of the first material layer at a certain place.

[0059] Based on different embodiments in Table 1, based on the total etching time, the etching rate V1 of the first material layer, and the etching selectivity for different etching targets, and based on the required total depth change value determined in Table 1, it can be simplified to obtain H1 = (KH - 80) / (K - 1). In Table 1, based on the designed total depth change value with continuous depth gradient, such as 20nm, 22nm, 25nm... 80nm, combined with the etching selectivity between the first material layer and the second material layer, the etching depths H1 at different positions within the depth continuous gradient functional region can be calculated respectively to carry out the next etching process. By calculating the etching depth H1 of the first material layer in step (2), it is used to correct and compensate for Figure 3 the over-etching phenomenon in, making it different from the conventional etching process. In the present invention, the etched part is corrected and compensated first to reduce subsequent over-etching, so that the structure formed after etching is as Figure 2 shown.

[0060] In the embodiments of the above table, based on the design requirements, the depth change range of the depth continuous gradient metasurface unit is limited to 20nm - 80nm. Of course, based on different design requirements, the depth change range of the metasurface unit is limited to other ranges, such as 20nm - 300nm, 200nm - 300nm, 20nm - 100nm, 100nm - 150nm, 100nm - 200nm and other parameter ranges. In this regard, the present invention does not limit the specific change values.

[0061] In this step, during etching, conventionally, SF6 is used as the core etching gas, and C4F8, CHF3, etc. are used as auxiliary etching gases, and then high-density plasma is formed for etching; while in step (2) of this method, the present invention uses fluorine-based gas to form a neutral ion gas cluster for etching, and the etching efficiency is relatively high; more specifically, the etching process of the present invention uses fluorine-based gas as the etching gas to form a neutral ion gas cluster, and etches the target structure area to reach the target gradient depth.

[0062] More specifically, in order to achieve the modulation of continuous depth gradient, in step (5), the flow rate range of the etching gas fluorine-based gas is limited to 10 - 125 sccm; the flow rate range of Ar is 10 - 500 sccm; the acceleration voltage Accel voltage range is 10 - 60 Kv; the ion bias current range is 10 - 200 mA.

[0063] The etching process of step (2), that is, in a high-vacuum state, after the etching gas is ionized, a charged ion gas cluster is formed, which is accelerated under the action of the acceleration voltage, and then neutralized through Ar ionization, so that the entire ion group is electrically neutral. After the electrically neutral ion gas cluster reaches the substrate surface, chemical and physical reactions occur on the surface to achieve the purpose of etching.

[0064] Through an etching process using a fluorine-based gas as the etching gas, on the one hand, the ionization gas clusters of the fluorine-based gas are used to modify the morphology of the gradient structure of the metasurface, such as surface roughness, etc., to achieve high-precision etching with a continuous depth gradient; on the other hand, the continuity of the depth between different metasurface sub-units is ensured, especially the boundary line problem between different metasurface depths, and the visualization problem of the boundary line between different sub-units is blurred or optimized as much as possible, reducing the appearance impact of the boundary line of the depth change of different metasurface sub-units on the metasurface structure, so as to improve the appearance of the metasurface unit.

[0065] Furthermore, in step (3), based on at least one depth-continuous gradient functional region formed by the previous-step etching, a certain thickness of photoresist is deposited in the functional region, as shown in Figure 4 step (3) of, and the surface of the photoresist is planarized to be flush with the surface of the first material layer.

[0066] In this step, the deposited photoresist completely fills different positions of the depth-continuous gradient functional region, and its surface is planarized to prevent the photoresist from not completely filling the functional region, preparing for the next process.

[0067] Furthermore, in step (4), based on the pre-reviewed pattern, the photoresist is patterned to form a patterned region.

[0068] In this step, based on the designed metasurface unit structure, especially for various parameters such as the diameter of each ring and the line width of each ring in several concentric rings, the corresponding photoresist is patterned.

[0069] In step (5), the first material layer 10 is etched, exposed and developed to obtain a depth-continuous gradient metasurface unit.

[0070] In this step, the process parameters for etching the first material layer 10 are defined as follows:

[0071] Chamber pressure (mTorr): 2.0 - 6.0;

[0072] Beam current (uA): 200 - 800;

[0073] Beam current (V): 300 - 1000;

[0074] Ar (sccm): 0 - 5;

[0075] O2 (sccm): 1 - 10;

[0076] Etching rate of the first material layer (nm / s): 0.5 - 3.

[0077] Based on the above etching process, etch the first material layer to form the required metasurface unit structure; during the etching process, adjust different etching parameters.

[0078] The metasurface structure provided by this application improves the structure of the existing continuously varying metasurface in depth, making the optical performance of optical products more excellent. At the same time, it also gives those skilled in the art more choices of metasurface unit structures, with a higher degree of freedom.

[0079] The structure of the continuously varying metasurface unit in depth proposed by this utility model is different from the prior art, and the preparation of the continuously varying metasurface unit in depth proposed is different from the prior art. Based on this, it has prominent substantive features and significant progress compared with the prior art.

[0080] The above specific embodiments do not constitute a limitation to the protection scope of this utility model. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of this utility model shall be included within the protection scope of this utility model.

Claims

1. A deep continuous gradient hypersurface unit, characterized in that: It at least comprises a first material layer, wherein any surface of the first material layer comprises at least one functional region, and the functional region comprises a plurality of super surface sub-units with continuously gradient depths.

2. A depth-continuously-gradient hypersurface unit according to claim 1, characterized in that: Each of the metasurface subunits includes a plurality of concentric rings.

3. A depth-continuously-gradient supersurface unit according to claim 1 or 2, characterized in that: It also includes a second material layer, which is formed on a surface of the first material layer away from the functional area.

4. A depth-continuously-gradient supersurface unit according to any one of claims 1 to 2, characterized in that: Each of the metasurface subunits includes a plurality of concentric rings, and each of the concentric rings has a different diameter.

5. A depth-continuously-gradient hypersurface unit according to claim 2, characterized in that: The line width of each of the circular rings is the same; or the line widths of at least two of the circular rings are different.

6. A depth-continuously-gradient hypersurface unit according to claim 5, characterized in that: The spacing between at least two of the circular rings is the same, and the spacing is the distance between adjacent circular rings.

7. A depth-continuously-gradient hypersurface unit according to claim 6, characterized in that: The spacing between at least two of the circular rings is different, and the spacing is the distance between adjacent circular rings.

8. The depth-continuously-gradient hypersurface unit according to claim 2, characterized in that: The structural size of the metasurface subunit ranges from 0.5 mm to 6 mm; the diameter of any of the concentric rings ranges from 50 nm to 6 mm.

9. A depth-continuously-gradient hypersurface unit according to claim 2, characterized in that: The line width of any of the concentric rings is in the range of 20 to 200 nm; the spacing between adjacent concentric rings is in the range of 50 nm to 150 nm.

10. A depth-continuously-gradient supersurface unit according to claim 1 or 2, characterized in that: The depth variation range of the depth-continuous-gradient-supersurface subunit in the supersurface unit is 20nm to 80nm.

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