Multi-level optical structure

Abstract

The present disclosure describes optical structures and methods for making the optical structures. In some implementations, a method includes imprinting a multi-level structured surface of a tool into an imprinting material disposed on a substrate such that the imprinting material is imprinted with a multi-level structure corresponding to the multi-level structured surface of the tool. The substrate includes sub-layers arranged on a support, and the sub-layers are arranged one above the other and include an optical sub-layer on the support, a first hard mask sub-layer on the optical sub-layer, a spacer sub-layer on the first hard mask sub-layer, and a second hard mask sub-layer on the spacer sub-layer. An etching operation is then performed such that the imprinted multi-level structure is transferred into the optical sub-layer of the substrate.

Description

Technical Field

[0001] The present disclosure relates to optical structures. Background Art

[0002] A tool (e.g., a mold) can be used to imprint a multi-level pattern into a layer on a substrate in which an optical element is to be formed. For example, such a tool can be used as part of a mass production manufacturing process. In some cases, the manufacture of optical elements can be performed at the wafer-level, where dozens, hundreds, or even thousands of optical elements are formed in parallel using the same tool. Summary of the invention

[0003] The present disclosure describes a multi-level optical structure and a method for making such a multi-level optical structure. The technique includes using a tool with a multi-level structured surface, which corresponds to the pixel layout design of an optical element, for example, and is transferred to an imprint material on a substrate by imprinting. Various etching operations can then be performed to transfer the imprinted pattern to the optical sublayer in the substrate.

[0004] In one aspect, for example, the present disclosure describes a method comprising: imprinting a multi-level structured surface of a tool into an imprint material disposed on a substrate so that the imprint material is imprinted with a multi-level structure corresponding to the multi-level structured surface of the tool. The substrate comprises sublayers disposed on a support. The sublayers are arranged one above the other and comprise an optical sublayer on the support, a first hard mask sublayer on the optical sublayer, a spacer sublayer on the first hard mask sublayer, and a second hard mask sublayer on the spacer sublayer. The method also comprises subsequently performing an etching operation so that the imprinted multi-level structure is transferred to the optical sublayer of the substrate.

[0005] Some implementations include one or more of the following features. For example, in some implementations, the multi-level structured surface of the tool corresponds to a pixel layout design of the optical element. For example, the optical element can include at least one of a diffractive optical element of a meta-optical element.

[0006] In some implementations, the optical sublayer is composed of amorphous silicon, crystalline silicon, silicon nitride, titanium oxide, aluminum zinc oxide, niobium oxide (e.g., NbO, NbO2, or Nb2O5), or zinc oxide. For example, the support can be composed of glass. In some cases, the hard mask sublayers are each composed of a metal. For example, at least one of the hard mask sublayers can be composed of chromium, aluminum, or titanium. In some cases, the spacer sublayer is composed of silicon dioxide. In some cases, the imprint material is a resist.

[0007] In some implementations, the etching operations are each selective etching. For example, in some implementations, performing the etching operations includes performing the following etches in sequence: a first etch to remove the residual layer of the imprint material; a second etch to remove the exposed portion of the second hard mask sublayer; a third etch to remove the exposed portion of the spacer sublayer; a fourth etch to remove the exposed portion of the first hard mask sublayer; a fifth etch to at least partially remove the exposed portion of the optical sublayer; a sixth etch to remove the remaining portion of the imprint material and the exposed portion of the spacer sublayer; a seventh etch to remove the remaining portion of the second hard mask sublayer and the exposed portion of the first hard mask sublayer; an eighth etch to remove the exposed portion of the optical sublayer; a ninth etch to remove the remaining portion of the spacer sublayer; and a tenth etch to remove the remaining portion of the first hard mask sublayer.

[0008] In some cases, the multi-level structured surface of the tool is imprinted into the imprint material by nanoimprint lithography. In some cases, the third etch also reduces the height of the imprint material. In some implementations, at least one of the etching operations is an inductively coupled plasma (ICP) etch.

[0009] In some implementations, the multi-level structure imprinted into the imprint material and transferred into the optical sub-layer of the substrate includes at least three different levels.

[0010] Some implementations can provide various advantages. For example, in some implementations, the multi-level structured surface of the tool is transferred to the optical sub-layer of the substrate by a process using only a single imprint.

[0011] Other aspects, features, and advantages will be apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a flow chart of a method according to the present disclosure.

[0013] Figure 2 A cross-sectional view showing an example of an imprinted layer on a substrate is illustrated.

[0014] Figure 3 Shown for Figure 2 Example sequence of etching operations to transfer the multi-level structure of the imprinted layer to the optical sub-layer of the substrate.

[0015] Figures 4 to 13 In some implementations, Figure 3 Example details of an etching operation.

[0016] Fig.14A It is a cross-sectional view of a multi-stage optical structure.

[0017] Fig. 14B yes Fig.14A Top view of the multi-level optical structure.

[0018] Fig.15A It is a cross-sectional view of a multi-stage optical structure.

[0019] Fig. 15B yes Fig.15A Top view of the multi-level optical structure.

[0020] Fig.16 An example showing the dimensions of a multi-level optical structure.

[0021] Fig.17 Another example of a multi-stage optical structure is shown.

[0022] Fig.18 An example of a single-channel module including an optical element having a multi-stage structure is shown.

[0023] Fig.19 An example of a multi-channel module including an optical element having a multi-stage structure is shown. DETAILED DESCRIPTION

[0024] This disclosure describes techniques for making multi-level optical structures including optical elements such as meta-optical elements (MOEs) or diffractive optical elements (DOEs). For example, a MOE can include a metasurface having a distributed array of meta-atoms (e.g., nanostructures). The meta-atoms can interact with light waves individually or collectively. For example, nanostructures or other meta-atoms can change the local amplitude, local phase, or both of an incoming light wave.

[0025] According to some implementations, a multi-level tool (e.g., a mold) can be used to imprint a multi-level structure into a layer on a substrate in which an optical element is to be formed. The tool can include a multi-level structured surface that corresponds to a pixel layout design of the multi-level optical element and can be transferred (e.g., by imprinting) to an imprinted material on a substrate. For example, the multi-level tool can be used as part of a mass production manufacturing process. In some cases, the manufacture of optical elements can be performed at the wafer level, where dozens, hundreds, or even thousands of optical elements are formed in parallel using the same tool.

[0026] like Figure 1As indicated at 10 in FIG. 1 , the technique may include, for example, by nanoimprint lithography (NIL), using a tool to transfer the multi-level pattern in the tool surface to an imprint layer on the substrate. Typically, the multi-level pattern imprinted into the imprint layer will be the negative of the multi-level pattern in the tool surface. Figure 2 As shown, substrate 30 includes several sublayers including an optical sublayer 22 on a glass or other support 20 that is substantially transparent to a particular wavelength or range of wavelengths (eg, 940 nm or a range in the infrared portion of the electromagnetic spectrum).

[0027] As a result of additional processes including various etching operations, the multi-level structure is transferred from the imprinted layer ( Figure 1 12) to the optical sublayer 22 on the glass or other support 20. In some cases, through the etching operation, the lateral dimensions of the multi-level structure can be transferred to the optical sublayer 22 with only slight changes (if any) in these dimensions. On the other hand, the longitudinal dimensions of the multi-level structure formed in the optical sublayer 22 can depend on, for example, the respective initial thicknesses of the sublayers of the substrate 30 and the etching time and etching rate for the sublayers.

[0028] The optical sub-layer 22 may be selected to have specific optical properties so that the optical elements formed therein by the resulting multi-level structure have specified optical characteristics and optical functionality at the operating wavelength(s).

[0029] like Figure 2 As further shown in FIG. 1 , the substrate 30 further includes a first hard mask (e.g., metal) sublayer 24 and a second hard mask (e.g., metal) sublayer 28 separated from each other by a spacer sublayer 26. The hard mask sublayers 24, 28 and the intervening spacer sublayer 26 may be arranged one above the other directly above the optical sublayer 22. The imprinted layer 32 in which the multi-level structure of the tool is imprinted is arranged on the second hard mask layer 28 farther from the optical sublayer 22.

[0030] In some implementations, for example, the support 20 can be a glass substrate having a thickness in the range of 0.5 mm-2.0 mm, a glass surface roughness Ra less than 2 nm, and a scratch / dig ratio of 60 / 20. The optical sublayer 22 can be, for example, composed of silicon (e.g., amorphous silicon, polycrystalline silicon, or crystalline silicon) having a thickness in the range of 300 nm-2000 nm and a surface roughness Ra less than 2 nm. In some cases, the optical sublayer 22 (at 940 nm) has the following optical properties: n=3.5±0.05 and k=6×10 -5 ±4×10 -5In other implementations, the optical properties of sublayer 22 may be different. For example, in some cases, the refractive index n is in the range of 3.4-3.9, and k<10 -3 Each of the hard mask sublayers 24, 28 may be composed, for example, of a metal (e.g., chromium (Cr)) with a thickness in the range of 5 nm-50 nm. For example, the hard mask chromium sublayers 24, 28 may be deposited by electron beam evaporation or sputtering. The intervening spacer sublayer 26 may be composed, for example, of SiO2 with a thickness in the range of 5 nm-100 nm.

[0031] The aforementioned materials, thicknesses and / or optical properties, and deposition techniques of the sublayers of substrate 30 are examples. Therefore, in some implementations, different materials, thicknesses and / or optical properties, and other deposition techniques may be used. For example, in some implementations, optical sublayer 22 may be made of silicon nitride (SiN x ) or titanium oxide (TiO2), and / or the hard mask sublayers 24, 28 can be composed of aluminum (Al) or titanium (Ti). Generally, the hard mask sublayers 24, 28 and the spacer sublayer 26 should be selected to allow selective etching of the sublayers of the substrate in a controlled manner.

[0032] In some implementations, the imprint layer 32 is a UV-curable, microwave-curable, and / or thermally curable epoxy or resin (eg, photoresist). Figure 2 As shown in the example of , the multi-level pattern structure imprinted into the imprint layer 32 produces three different levels L1, L2, and L3. That is, the various features in the imprinted structure are at a corresponding one of these levels. In the example shown, after imprinting, there is a residual layer (e.g., a residual layer of resist) with a thickness (RL) of approximately 50nm-70nm. In this example, the height (H1) of the second level L2 is approximately 90nm, and the height (H2) of the third level L3 is approximately 90nm. For some implementations, these values ​​may be different. In addition, although the foregoing examples describe a multi-level structure with three levels (and two platforms), more generally, imprinting techniques can be used to create a multi-level pattern with N levels (and N-1 platforms), where the value of N is at least 3. Therefore, in some cases, imprinting techniques can be used to create a multi-level pattern with four, five, six, or more than six levels.

[0033] As described above, after the pattern is transferred to the imprint layer 32 by embossing, various etching operations are performed, the result of which is that the multi-level pattern is transferred to the optical sublayer 22 located on the glass or other support 20. In a specific example described in more detail below, the process includes at least ten etching operations (see Figure 3). However, other implementations may include different numbers of etches, different types of etches, and / or etches performed in different orders. In addition, other details of the etches described below may be different in some implementations.

[0034] A first etch is performed to remove the remaining layer of imprint material (eg, resist) 32. Figure 4 The result of this etching according to an example implementation is shown in FIG. Figure 4 It is shown that the height (H1) at which the first platform is located is about 40 nm and the height (H2) at which the second platform is located is about 90 nm. That is, during the first etching, the height of the resist pattern is reduced by about 50 nm. + In some cases, the etching can be achieved by using inductively coupled plasma (ICP).

[0035] Next, a second etch is performed to remove the exposed portion of the second hard mask sublayer 28. During this etch, the imprint material 32 acts as a mask that substantially prevents the portion of the second hard mask sublayer 28 directly below the imprint material 32 from being etched. Figure 5 The result of this etching according to an example implementation is shown in , and shows that the exposed portion of the second hard mask sublayer 28 is selectively etched away. The portion of the hard mask sublayer 28 directly below the imprint material (e.g., resist) 32 remains. In some cases, this etching can be achieved by using ICP.

[0036] Then, a third etch is performed to remove the exposed portions of the spacer sublayer 26 and reduce the height of the remaining imprint layer 32. During this etch, the second hard mask sublayer 28 acts as a mask that substantially prevents the spacer (e.g., SiO2) sublayer 26 directly below the second hard mask sublayer 28 from being etched. Figure 6 The result of this etching according to an example implementation is shown in FIG. 1 and shows that the exposed portion of the spacer (e.g., SiO2) sublayer 26 is selectively etched away. Furthermore, in this example, the height (H2) of the second level (L2) is reduced to approximately 40 nm by this third etch. That is, in the example shown, the height of the imprinted layer 32 is reduced by approximately 50 nm during this third etch. + In some cases, this etching can be achieved by using ICP.

[0037] Then, a fourth etch is performed to remove the exposed portions of the first hard mask sublayer 24. During this etch, the spacer (e.g., SiO2) sublayer 26 acts as a mask that substantially prevents portions of the first hard mask sublayer 24 directly below the spacer sublayer 26 from being etched. Figure 7The result of this etching according to an example implementation is shown in FIG. 1 and shows that the exposed portion of the first hard mask sublayer 24 is selectively etched away. The portion of the first hard mask sublayer 24 directly below the spacer (e.g., SiO2) sublayer 26 remains. In addition, during this fourth etch, as shown in FIG. Figure 7 As shown, the exposed portions of second hard mask sublayer 28 are selectively etched away. However, imprint material 32 acts as a mask that substantially prevents etching of second hard mask sublayer 28 directly beneath imprint material 32. In some cases, this etching can be accomplished using ICP.

[0038] Then, a fifth etch is performed to at least partially remove the exposed portion of the optical (e.g., amorphous silicon) sublayer 22. During this etch, the spacer sublayer (e.g., SiO2) 26 and / or the first hard mask sublayer 24 are used as a mask to substantially prevent portions of the optical sublayer 22 directly beneath these sublayers from being etched. Figure 8 , according to an example implementation, and shows that the exposed portion of the optical (e.g., amorphous silicon) sublayer 22 is selectively etched away. In some implementations, the fifth etch is performed until the surface of the support 20 is exposed. In other implementations, it may be desirable to stop the fifth etch and retain some exposed optical sublayer 22. In some cases, the etch may be implemented using ICP.

[0039] Then, a sixth etch is performed to remove the remaining portions of the imprint layer (e.g., resist) 32 and the exposed portions of the spacer (e.g., SiO2) sublayer 26. During this etch, the second hard mask sublayer 28 is used as a mask to substantially prevent the portions of the spacer (e.g., SiO2) sublayer 26 directly beneath these sublayers from being etched. Fig. 9 The result of this etch according to an example implementation is shown in , and shows that the exposed portion of the spacer (eg, SiO 2 ) sublayer 26 and the remaining portion of the imprint layer 32 are selectively etched away. In some cases, this sixth etch can be implemented using ICP.

[0040] Then, a seventh etch is performed to remove the remaining portion of the second hard mask sublayer 28 and the exposed portion of the first hard mask sublayer 24. The spacer (e.g., SiO2) sublayer 26 is used as a mask to substantially prevent the portion of the first hard mask sublayer 24 directly below the spacer sublayer from being etched. Fig.10 The result of this etching according to an example implementation is shown in , and shows that the remaining portion of the second hard mask sublayer 28 and the exposed portion of the first hard mask sublayer 24 are selectively etched away. In some cases, ICP can be used to implement this etching.

[0041] Then, an eighth etch is performed to remove the exposed portions of the optical (e.g., amorphous silicon) sublayer 22. The spacer (e.g., SiO2) sublayer 26 and the first hard mask sublayer 24 are used as masks to substantially prevent the portions of the optical (e.g., amorphous silicon) sublayer 22 directly beneath these sublayers from being etched. Fig.11 The result of this etching according to an example implementation is shown in , and shows that the exposed portion of the optical (e.g., amorphous silicon) sublayer 22 is selectively etched away. In some cases, ICP can be used to achieve this etching. In some cases, it may be desirable to use an atomic force microscope (AFM) to monitor the etching depth.

[0042] Then, a ninth etch is performed to remove the remaining portion of the spacer (e.g., SiO2) sublayer 26. Fig.12 The result of this etching according to an example implementation is shown in , and shows that the remaining portion of the spacer sublayer 26 is selectively etched away. In some cases, ICP can be used to achieve this etching.

[0043] Then, a tenth etch is performed to remove the remaining portion of the first hard mask sublayer 24. Fig.13 The result of this etching according to an example implementation is shown in , and shows that the remaining portion of the first hard mask sublayer 24 is selectively etched away. In some cases, ICP can be used to implement this etching. Fig.13 and Figure 2 A comparison of 300 and 310 shows that as a result of the sequential etching operations, the multi-level structure imprinted into the imprint layer (e.g., resist) 32 has been transferred to the optical (e.g., amorphous silicon) sublayer 22. As noted above, in some cases, the foregoing techniques can enable the lateral dimensions of the multi-level structure to be transferred to the optical sublayer 22 with only minor changes, if any, to those dimensions.

[0044] In some implementations, a cleaning operation is performed prior to cutting the optical element and subsequently performing optical properties. In some implementations, the cleaning operation includes using a piranha solution of sulfuric acid (98%) and hydrogen peroxide (30%) in a ratio of 4:1 for about 10 minutes, followed by a water rinse for about 8 minutes. The substrate(s) may then be dried, for example, in a drum dryer. In some implementations, different or additional cleaning techniques may be used.

[0045] The optical properties of the resulting optical element can then be determined, for example, using known techniques. The glass or other support 20 can then be separated, for example by cutting, into individual optical elements (e.g., DOEs or MOEs), each of which includes a multi-stage structure defined by at least three different stages. Depending on the materials of the multi-stage structure, the optical element can be configured to be operable for use, for example, with infrared (IR) or visible radiation. The depth and position of the stages relative to each other can be configured according to predefined optical functions.

[0046] In some implementations, an optical element having a multi-level structure as described above can be integrated into a module that houses one or more optoelectronic devices (e.g., a light emitting device and / or a light sensing device). The optical element can be used to modify or redirect an emitted or incoming light wave as it passes through the optical element.

[0047] The foregoing techniques can facilitate the manufacture of optical elements having a multi-level structure whose features are circular, elliptical, square, rectangular, or some other shape in a top view (i.e., a view viewed perpendicular to the surface of substrate 20). For example, Fig.14A and Fig. 14B Examples of circular features 22A, 22B are shown. Likewise, Fig.15A and Fig. 15B An example of feature 22C having an elliptical shape is shown. Additionally, in some implementations, one or more features can have a free-form shape in a top view. Fig.15A and Fig. 15B An example including a feature 22D having a free-form shape is shown in FIG.

[0048] Fig.16 An example of a glass support 20 is shown on which a number of multi-stage optical elements 22E, 22F, 22G are arranged. For example, the above-mentioned techniques can be used to obtain Fig.16 In the example shown, the optical structure has three different levels L1, L2, L3. In some implementations, the optical elements 22E, 22F, 22G may include features having the following dimensions. For example, in some cases, Fig.16 As shown, the heights H1 and H2 are each in the range of 50nm-3000nm, and the total height H=H1+H2 is in the range of 100nm-6000nm. In some cases, the diameter D2 can be as small as 30nm-50nm. The diameter D1 can be greater than D2, and the edge spacing Se between the level L2 and the level L3 is at least 20nm-70nm. The minimum spacing S between adjacent optical elements is 30nm-100nm. In some implementations, different values ​​(i.e., smaller or larger values) of the aforementioned dimensions can be used.

[0049] In some implementations, one or more than one level of the optical structure can be made of more than one material. Likewise, different levels of the optical structure can be made of different materials from each other. Fig.17 As shown, optical elements 22H, 22I, 22J each have a structural upper level composed of a first material 50A, and a structural lower level composed of a second material 50B and a third material 50C, one on top of the other. For example, materials 50A, 50B, 50C can each be a different optical material with a relatively high refractive index (e.g., amorphous silicon, silicon nitride, titanium oxide, zinc aluminum oxide, niobium oxide (e.g., NbO, NbO2 or Nb2O5), zinc oxide, or a transparent conductor material). For example, the materials can be selected based on their optical and other properties to provide a specific optical function at a given wavelength or wavelength range (e.g., a wavelength or wavelength range in the infrared or visible portion of the spectrum).

[0050] The optical element having the multi-level structure as described above can be integrated into, for example, a light sensing module or a light emitting module. Fig.18 As shown, a light sensing module (e.g., an ambient light sensor module) 800 includes an active optoelectronic device 802 mounted on a bottom surface 803. The optoelectronic device 802 may be, for example, a light sensor (e.g., a photodiode, a pixel, or an image sensor) or a light emitter (e.g., a laser such as a vertical cavity surface emitting laser, or a light emitting diode). The module housing may, for example, include a spacer 810 separating the optoelectronic device 802 and / or the bottom surface 803 from an optical element 804 having a multi-level structure as described above.

[0051] exist Fig.18 In a single-channel module of FIG. 800 , the optical element 804 can be arranged to intersect the path of incoming light, or to intersect the path of outgoing light. The optical element can be aligned with the active optoelectronic component 802 and can be mounted to the housing. In some cases (e.g., where the optoelectronic component is a light sensor), the light incident on the module 800 is modified or redirected by the optical element 804. For example, in some cases, the optical element 804 modifies one or more characteristics of the light before the light impinging on the optical element is received and sensed by the optoelectronic component 802. In some cases, for example, the optical element 804 can focus patterned light onto the optoelectronic component 802. In some cases, the optical element 804 can split, scatter, and / or polarize the light before the light is received and sensed by the optoelectronic component 802.

[0052] In some cases (e.g., where optoelectronic component 802 is a light emitter), light generated by optoelectronic component 802 passes through optical element 804 and exits the module. Fig.18In a single-channel module of FIG. 800 , optical element 804 can be arranged to intersect the path of outgoing light 806. Optical element 804 can modify or redirect light. For example, in some cases, one or more characteristics of the light that strikes the optical element are modified before the light exits module 800. In some cases, module 800 can be operated to, for example, generate one or more of structured light, scattered light, or patterned light.

[0053] One or more optical elements having a multi-stage structure as described can also be integrated into a multi-channel module. Fig.19 As shown, such a multi-channel module 900 may, for example, include a light sensor 902A and a light emitter 902B, both of which may be mounted on the same printed circuit board (PCB) or other bottom surface 903. In the example shown, an optical element 904 having a multi-stage structure as described above is mounted to a housing above the light emitter 902B. The multi-channel module may include a light emission channel and a light detection channel, which may be optically isolated from each other by a wall forming a part of the module housing. A lens 905 may be provided above the light sensor 902A.

[0054] In some cases, one or more of the above modules may be integrated into, for example, a mobile phone, a laptop computer, a television, a wearable device, or a motor vehicle.

[0055] Although this article contains many specific implementation details, these should not be interpreted as limitations on the scope of any invention or the scope of the content that may be claimed, but as descriptions of features specific to a particular embodiment. Certain features described herein in the context of a separate embodiment may also be implemented in a single embodiment in a combined form. Conversely, the various features described in the context of a single embodiment may also be implemented in multiple embodiments, respectively, or in the form of any suitable sub-combination. Various modifications may be made to the aforementioned examples. Accordingly, other implementations are also within the scope of the appended claims.

Claims

1. A method comprising: Imprinting the multi-level structured surface of the tool into an imprint material arranged on a substrate, so that the imprint material is imprinted with a multi-level structure corresponding to the multi-level structured surface of the tool, wherein the substrate comprises a plurality of sub-layers arranged on a support, the plurality of sub-layers being arranged one above the other and comprising an optical sub-layer on the support, a first hard mask sub-layer on the optical sub-layer, a spacer sub-layer on the first hard mask sub-layer, and a second hard mask sub-layer on the spacer sub-layer; as well as A plurality of etching operations are then performed so that the imprinted multi-level structure is transferred into the optical sub-layer of the substrate.

2. The method according to claim 1, wherein: The optical sublayer is made of amorphous silicon, polycrystalline silicon or crystalline silicon.

3. The method according to claim 1, wherein: The optical sublayer is made of silicon nitride, titanium oxide, zinc oxide, silicon carbide, zinc aluminum oxide, niobium oxide or gallium nitride.

4. The method according to any one of claims 1 to 3, wherein: The hard mask sub-layers are each composed of metal.

5. The method according to claim 3, wherein: At least one of the hard mask sublayers is comprised of chromium.

6. The method according to claim 3, wherein: At least one of the hard mask sublayers is composed of aluminum or titanium.

7. The method according to any one of claims 1 to 6, wherein: The spacer sublayer is made of silicon dioxide or silicon nitride.

8. The method according to any one of claims 1 to 7, wherein: Each of the plurality of etching operations is a selective etch.

9. The method according to any one of claims 1 to 8, wherein: The imprint material includes a resist.

10. The method according to claim 1, wherein: The optical sublayer is composed of silicon, the first hard mask sublayer and the second hard mask sublayer are each composed of chromium, the spacer sublayer is composed of silicon dioxide, and the imprint material is a resist.

11. The method according to claim 1 or 10, wherein: Performing multiple etching operations includes performing the following etchings in sequence: a first etch for removing a residual layer of the imprint material; a second etch for removing an exposed portion of the second hard mask sublayer; a third etch for removing the exposed portion of the spacer sublayer; a fourth etch for removing an exposed portion of the first hard mask sublayer; a fifth etch for at least partially removing the exposed portion of the optical sublayer; a sixth etch for removing a remaining portion of the imprint material and an exposed portion of the spacer sublayer; a seventh etch for removing a remaining portion of the second hard mask sublayer and an exposed portion of the first hard mask sublayer; An eighth etching step for removing an exposed portion of the optical sublayer; A ninth etching step for removing a remaining portion of the spacer sublayer; as well as A tenth etch is used to remove a remaining portion of the first hard mask sublayer.

12. The method according to claim 11, wherein: The third etch also reduces the height of the imprint material.

13. The method according to any one of claims 1 to 12, wherein: At least one of the plurality of etching operations is an inductively coupled plasma etch, or ICP etch.

14. The method according to any one of claims 1 to 13, wherein: The multilevel structured surface of the tool is imprinted into the imprint material by nanoimprint lithography.

15. The method according to any one of claims 1 to 14, wherein: The multi-level structured surface of the tool corresponds to the pixel layout design of the optical element.

16. The method according to claim 15, wherein: The optical element includes at least one of the diffractive optical elements of a meta-optical element.

17. The method according to any one of claims 1 to 16, wherein: The support body consists of glass.

18. The method according to any one of claims 1 to 17, wherein: The multi-level structure imprinted into the imprint material and transferred into the optical sublayer of the substrate comprises at least three different levels.

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