Oblique grating preparation method and oblique grating

Abstract

The invention relates to an oblique grating preparation method and an oblique grating. The oblique grating preparation method comprises the following steps: preparing a middle grating; filling a gap between the middle gratings with an oblique grating material to obtain a middle substrate; performing planarization processing on the middle substrate to remove the filling material exceeding the height of the middle grating; and removing the middle grating to obtain the oblique grating. According to the preparation method of the inclined grating, the middle grating with good morphological characteristics is prepared firstly, then the flat middle substrate is obtained through filling of the inclined grating material and planarization processing, and finally the inclined grating is prepared in a mode of removing the middle grating. The appearance problems that the bottom of the grating is uneven, the side wall of the top of the grating is uneven and the like existing in the inclined grating prepared by a traditional etching preparation method are solved, and the inclined grating with intact morphological characteristics can be prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular to a method for preparing a slant grating and the slant grating. Background Art

[0002] Slanted gratings are high-performance optical components with a periodic spatial structure. They are widely used in fields such as virtual reality (VR) and augmented reality (AR). Currently, slanted gratings are fabricated using two main methods: imprinting and etching.

[0003] The imprinting method involves first preparing an imprint template for the slanted grating, then using the imprint template to imprint a grating material layer, and finally curing the imprinted grating material layer to obtain the slanted grating structure. This imprinting method offers low cost and high precision, making it ideal for large-scale production. However, due to the slanted grating structure and the susceptibility of the imprinting material to temperature or plasma, the imprinted grating material layer can deform arbitrarily during demolding of the imprint template, resulting in poor grating shape.

[0004] The etching method uses reactive ion etching, reactive ion beam etching, or ion beam etching to remove the mask material from the substrate, forming the slanted grating. This method avoids the deformation of the slanted grating material layer that occurs with imprinting methods. However, existing slanted gratings produced using this method often suffer from appearance issues such as an uneven bottom and uneven sidewalls at the top. Summary of the Invention

[0005] Based on this, it is necessary to provide a slant grating preparation method and a slant grating to address the appearance problems of the slant grating prepared by the existing etching preparation method, such as uneven grating bottom and uneven sidewall of the grating top.

[0006] A method for preparing a slanted grating, comprising the steps of:

[0007] preparing an intermediate grating;

[0008] filling the gaps between the intermediate gratings with slanted grating materials to obtain an intermediate substrate;

[0009] performing a planarization process on the intermediate substrate to remove the filling material exceeding the height of the intermediate grating; and

[0010] The intermediate grating is removed to obtain a slanted grating.

[0011] In one embodiment, the step of preparing the intermediate grating includes:

[0012] coating a coating material onto a base substrate to form a coating layer on the base substrate; and

[0013] Oblique grating etching is performed on the coating layer to obtain an intermediate grating.

[0014] In one embodiment, the step of coating the coating material onto the base substrate to form a coating layer on the base substrate comprises the following steps:

[0015] preparing a base layer;

[0016] plating an isolation material onto the base layer to form an isolation layer on the base layer, thereby obtaining the base substrate; and

[0017] A coating material is plated onto the isolation layer to form a coating layer on the isolation layer.

[0018] In one embodiment, the step of performing oblique grating etching on the coating layer to obtain the intermediate grating comprises the steps of:

[0019] applying a mask material onto the coating layer to form a mask layer on the coating layer;

[0020] Performing pattern definition on the mask layer to form a mask pattern layer on the mask layer;

[0021] etching the mask layer through the mask pattern layer to form an etched pattern; and

[0022] The coating layer is etched according to the etching pattern to obtain an intermediate grating.

[0023] In one embodiment, in the step of etching the mask layer through the mask pattern layer to form an etched pattern, the sum of the width of the ridge of the etched pattern and the width of the ridge of the slant grating prepared by the slant grating preparation method is equal to the period of the etched pattern.

[0024] In one embodiment, in the step of etching the mask layer through the mask pattern layer to form an etching pattern, the mask layer is dry-etched by using chlorine, oxygen, or argon to obtain the etching pattern.

[0025] In one embodiment, the coating material is one or more of silicon dioxide, amorphous silicon, and silicon nitride.

[0026] In one embodiment, after the step of etching the coating layer according to the etching pattern to obtain the intermediate grating, the method further includes the following steps:

[0027] The mask layer is wet-etched to remove the mask layer.

[0028] In one embodiment, in the step of etching the coating layer according to the etching pattern to obtain the intermediate grating, one or more of carbon tetrafluoride, octafluorocyclobutane, sulfur hexafluoride and argon are used, and the coating layer is etched using a reactive ion beam etching machine to obtain the intermediate grating.

[0029] In one embodiment, in the step of filling the gaps between the intermediate gratings with the slanted grating material to obtain the intermediate substrate, the gaps between the intermediate gratings with the slanted grating material are filled with the slanted grating material by an atomic layer deposition coating machine.

[0030] In one embodiment, the filling material is one or more of titanium dioxide, niobium pentoxide, and aluminum oxide.

[0031] In one embodiment, in the step of planarizing the intermediate substrate to remove the filling material exceeding the height of the intermediate grating, the intermediate substrate is planarized by a chemical mechanical polishing machine to remove the portion exceeding the intermediate grating.

[0032] In one embodiment, the step of flattening the intermediate substrate to remove the filling material exceeding the height of the intermediate grating and the step of removing the intermediate grating to obtain the slanted grating further includes the following steps:

[0033] The intermediate substrate after the planarization process is further polished by a chemical mechanical polishing machine to adjust the overall height of the intermediate substrate.

[0034] In one embodiment, in the step of removing the intermediate grating to obtain the slanted grating, the coating material is corroded by a chemical solution to remove the intermediate grating.

[0035] In one embodiment, the drug solution is a tetramethylhydroxylamine solution or a hydrofluoric acid solution.

[0036] A slant grating is prepared by any of the slant grating preparation methods described above.

[0037] The above-mentioned slanted grating preparation method first prepares an intermediate grating with good morphological characteristics, then obtains a flat intermediate substrate by filling the slanted grating material and flattening the substrate, and finally removes the intermediate grating to prepare the slanted grating. This overcomes the appearance problems of the slanted grating prepared by the traditional etching preparation method, such as the uneven grating bottom and the uneven sidewall of the grating top, and can prepare a slanted grating with intact morphological characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic flow chart of a method for preparing a slanted grating provided in one embodiment of the present application;

[0039] Figure 2 1 is a flow chart showing step S100 of the method for preparing a slanted grating according to the above embodiment of the present application;

[0040] Figure 3 1 is a flow chart showing step S110 of the method for preparing a slanted grating according to the above embodiment of the present application;

[0041] Figure 4 FIG2 is a flow chart showing step S120 of the method for preparing a slanted grating according to the above embodiment of the present application;

[0042] Figure 5 A schematic flow chart showing a modified example of the method for preparing a slanted grating according to the above embodiment of the present application is shown;

[0043] Figure 6 A schematic diagram of substrate changes during preparation of a slant grating according to the slant grating preparation method of the above embodiment of the present application is shown.

[0044] Figure numerals: 11, base substrate; 111, base layer; 112, isolation layer; 12, coating layer; 121, intermediate grating; 13, mask layer; 14, mask pattern layer; 15, intermediate base; 151, slanted grating. DETAILED DESCRIPTION

[0045] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0046] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0048] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0049] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0050] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0051] Specifically, if Figure 1 and Figure 6 As shown, the present application provides a method for preparing a slant grating, which is used to prepare a slant grating 151. The method for preparing a slant grating includes the following steps:

[0052] S100, preparing an intermediate grating;

[0053] S200, filling the gaps between the intermediate gratings with slanted grating materials to obtain an intermediate substrate;

[0054] S300, performing a planarization process on the intermediate substrate to remove the filling material exceeding the height of the intermediate grating; and

[0055] S400: Remove the intermediate grating to obtain a slanted grating.

[0056] It is understood that the slant grating preparation method first prepares the intermediate grating 121 in step S100; then, in step S200, the intermediate grating 121 is filled with the slant grating material to form the intermediate substrate 15; then, in step S300, the intermediate substrate 15 is flattened to remove the filling material that exceeds the height of the intermediate grating 121; and finally, in step S400, the intermediate grating 121 is removed, so that the slant grating material forms the slant grating 151 on the base substrate 11. The bottom of the slant grating 151 is the surface of the base substrate 11. Therefore, the grating bottom of the slant grating 151 has a high degree of flatness, and the sidewalls of the grating top of the slant grating 151 also have a high degree of flatness after the flattening process in step S400. In this way, the slant grating preparation method first prepares the intermediate grating 121 with good morphological features, then obtains the flat intermediate substrate 15 by filling the slant grating material and flattening treatment, and finally removes the intermediate grating 121 to prepare the slant grating 151. This overcomes the appearance problems of the slant grating 151 prepared by the traditional etching preparation method, such as the uneven grating bottom and the uneven side wall of the grating top, and can prepare a slant grating 151 with intact morphological features.

[0057] More specifically, if Figure 2 and Figure 6 As shown, in one embodiment of the present application, the step of preparing the intermediate grating includes:

[0058] S110, coating a coating material onto a base substrate to form a coating layer on the base substrate; and

[0059] S120 , performing oblique grating etching on the coating layer to obtain an intermediate grating.

[0060] In step S110, the coating material is deposited onto the base substrate 11 to form a coating layer 12 for forming the intermediate grating 121. In step S120, the coating layer 12 is etched with the slanted grating 151 to form the intermediate grating 121. In this manner, the combination of steps S110 and S120 forms the intermediate grating 121 on the base substrate 11, paving the way for the subsequent formation of the slanted grating 151 on the base substrate 11.

[0061] Preferably, if Figure 3 and Figure 6 As shown, in one embodiment, the step of coating the coating material onto the base substrate to form a coating layer on the base substrate includes the steps of:

[0062] S111, preparing a base layer;

[0063] S112, plating an isolation material onto the base layer to form an isolation layer on the base layer, thereby obtaining the base substrate; and

[0064] S113, coating the coating material on the isolation layer to form a coating layer on the isolation layer.

[0065] In step S111, a base layer 111 of a base substrate 11 is first prepared. Then, in step S112, an isolation layer 112 is formed on the base layer 111. In step S113, a coating layer 12 is formed on the isolation layer 112, thereby separating the coating layer 12 from the base layer 111. Thus, on the one hand, the isolation layer 112 can protect the base layer 111 during etching of the intermediate grating 121, thereby preventing the base layer 111 from being damaged. On the other hand, the isolation layer 112 can protect the base layer 111 during removal of the intermediate grating 121, thereby maintaining the morphological features of the base layer 111 intact, so that the finally formed slanted grating 151 has good morphological features.

[0066] It is worth noting that the material of the isolation layer 112 is the same as that of the slanted grating. In this way, the isolation layer 112 can serve as the base of the slanted grating 151, making the grating bottom of the slanted grating 151 smoother and the morphology more complete.

[0067] Optionally, the base layer 111 may be high-refractive glass or low-refractive glass.

[0068] Furthermore, if Figure 4 and Figure 6 As shown, in one embodiment, the step of performing oblique grating etching on the coating layer to obtain the intermediate grating includes the steps of:

[0069] S121, applying a mask material onto the coating layer to form a mask layer on the coating layer;

[0070] S122, performing pattern definition on the mask layer to form a mask pattern layer on the mask layer;

[0071] S123, etching the mask layer through the mask pattern layer to form an etching pattern; and

[0072] S124, etching the coating layer according to the etching pattern to obtain an intermediate grating.

[0073] The mask layer 13 can block etching of the coating material. Based on the etching pattern of the mask layer 13, the desired intermediate grating 121 can be etched on the coating layer 12. Therefore, a mask layer 13 is first formed on the coating layer 12 in step S121. Then, a mask pattern layer 14 required for etching the mask layer 13 is defined on the mask layer 13 in step S122. Then, an etching pattern is etched on the mask layer 13 in step S123. Finally, the intermediate grating 121 is etched in step S124. The intermediate grating 121 etched through the above steps has good morphological characteristics, which can ensure that the subsequently fabricated slanted grating 151 also has good morphological characteristics.

[0074] Optionally, in step S122 , an electron beam exposure machine or a scanning exposure machine may be used to perform pattern definition on the mask layer 13 .

[0075] Since the intermediate grating 121 is removed in step S400, the remaining grating pattern is the slanted grating 151 prepared by the slanted grating preparation method. Therefore, the intermediate grating 121 and the slanted grating 151 are inverse versions of each other, that is, the sum of the width of the ridges of the adjacent intermediate gratings 121 and the width of the ridges of the slanted grating 151 is one period of the etched pattern.

[0076] Therefore, in one embodiment, during the step of etching the mask layer through the mask pattern layer to form an etched pattern, the sum of the width of the ridges of the etched pattern and the width of the ridges of the slanted grating produced by the slanted grating production method is equal to the period of the etched pattern. For example, if the pattern period is defined as 300 nm, and the period of an etched pattern includes ridges (lines) and grooves (spaces), and the ridge width is defined as 130 nm, then the ridge width of the slanted grating 151 is ultimately 170 nm. Alternatively, if the ridge width is defined as 200 nm, then the ridge width of the slanted grating 151 is ultimately 100 nm.

[0077] Optionally, in step S121 , the mask material may be chromium material.

[0078] For example, in one embodiment, during the step of etching the mask layer through the mask pattern layer to form an etched pattern, the mask layer 13 is dry-etched using chlorine (Cl2), oxygen (O2), and argon (Ar) to obtain the etched pattern. In other words, the chemical properties of chlorine, oxygen, and argon react with the mask layer 13 to remove the corresponding mask layer 13. Thus, through the above steps, the corresponding mask material can be removed according to the mask pattern layer 14, thereby etching the desired etched pattern in the mask layer 13, thereby subsequently etching the desired intermediate grating 121.

[0079] In particular, due to the chemical properties of chlorine, oxygen, and argon, certain requirements are placed on the selection of coating materials. In the slanted grating fabrication method provided herein, the coating material is selected based on the aforementioned dry etching process. Specifically, the coating material does not react with the chemical gases used during dry etching of the mask. This protects the coating layer 12 from damage during the definition of the etched pattern, preventing any impact on the morphological features of the subsequently formed intermediate grating 121 and slanted grating 151.

[0080] Optionally, in one embodiment, the coating material may be a silicon-containing material, such as one or more of silicon dioxide (SiO2), amorphous silicon (α-Si), and silicon nitride (SiN). Silicon dioxide, amorphous silicon, and silicon nitride have excellent etching properties and are not damaged when defining the etched pattern, ensuring good morphological features of the intermediate grating 121. Silicon dioxide and amorphous silicon are preferred as coating materials.

[0081] Furthermore, if Figure 4 and Figure 6 As shown, in one embodiment, after the step of etching the coating layer according to the etching pattern to obtain the intermediate grating, the method further includes the following steps:

[0082] S125 , performing wet etching on the mask layer to remove the mask layer.

[0083] Since the intermediate grating 121 needs to be removed in the subsequent step S400 , after the intermediate grating 121 is completed, the mask layer 13 is removed in step S125 so that the intermediate grating 121 loses the protection of the mask layer 13 , facilitating the subsequent removal of the intermediate grating 121 .

[0084] Optionally, in one embodiment, in the step of etching the coating layer according to the etching pattern to obtain the intermediate grating, the coating layer 12 is etched using one or more of carbon tetrafluoride (CF4), octafluorocyclobutane (C4F8), sulfur hexafluoride (SF6), and argon (Ar) using a reactive ion beam etching (RIB) machine to obtain the intermediate grating 121. The RIB machine has good etching depth uniformity, which can ensure that the etched intermediate grating 121 has good morphological characteristics. In this step, the leading and trailing edges of the ridges of the intermediate grating 121 are required to remain as parallel as possible. The tilt of the ridges can be adjusted according to actual needs, and is generally required to maintain an angle of 10° to 45° with the normal to the plane of the base substrate 11. In addition, the curvature of the bottom of the intermediate grating 121 does not exceed 10 nm, and the height of the slanted grating 151 can also be adjusted according to actual needs.

[0085] Optionally, there are multiple filling methods for step S200. In one embodiment, in the step of filling the gaps between the intermediate gratings with the slanted grating material to obtain the intermediate substrate, the slanted grating material is filled into the gaps between the intermediate gratings using an atomic layer deposition (ALD) coating machine. The atomic layer deposition coating machine has good step coverage, which can take into account the gaps between the intermediate gratings 121. Compared with other coating methods, it can obtain an intermediate substrate 15 that meets the requirements of the slanted grating preparation method. Other coating methods can also meet the requirements of the slanted grating preparation method by adjusting the process.

[0086] Optionally, in one embodiment, the filler material is one or more of titanium dioxide (TiO2), niobium pentoxide (Nb2O5), and aluminum oxide (Al2O3). Titanium dioxide, niobium pentoxide, or aluminum oxide has a relatively high refractive index, and materials with a high refractive index are more stable during etching than during imprinting. Selecting titanium dioxide, niobium pentoxide, or aluminum oxide can produce a slanted grating 151 with excellent morphological characteristics.

[0087] Optionally, in one embodiment, during the step of flattening the intermediate substrate to remove the filler material that exceeds the height of the intermediate grating, the intermediate substrate is flattened using a chemical mechanical polishing (CMP) machine to remove the portion that exceeds the intermediate grating. In this manner, the flattening process defines and adjusts the height of the resulting slanted grating 151, thereby making the grating top of the resulting slanted grating 151 more flat.

[0088] Preferably, if Figure 5 and Figure 6 As shown, in one embodiment, the step of flattening the intermediate substrate to remove the filling material exceeding the height of the intermediate grating and the step of removing the intermediate grating to obtain the slanted grating further includes the following steps:

[0089] S400 , further grinding the intermediate substrate after the planarization process by a chemical mechanical grinding machine to adjust the overall height of the intermediate substrate.

[0090] Through the above step S400 , the height of the intermediate substrate 15 can be adjusted to a desired height, thereby adjusting the height of the finally formed slanted grating 151 .

[0091] For example, the height of the intermediate grating 121 made of silicon dioxide is 300 nm, the height of the intermediate substrate 15 after filling with titanium dioxide is 350 nm, and the height required for preparing the titanium dioxide slant grating 151 is 250 nm. The height can be adjusted to 250 nm by using a chemical mechanical polishing machine to obtain the titanium dioxide slant grating 151 that meets the requirements.

[0092] Because the refractive index of this coating material is relatively low, it cannot meet the requirements of certain conditions, such as in diffraction waveguides. The high-refractive-index slanted grating 151 provides higher diffraction efficiency. If the intermediate grating 121 is retained, the high-refractive-index slanted grating 151 will produce a thin film effect, affecting the diffraction efficiency of the grating within the angular range, resulting in poor diffraction uniformity and difficulty meeting practical requirements. Therefore, it is necessary to remove the intermediate grating 121 and retain the high-refractive-index slanted grating 151.

[0093] Preferably, in one embodiment, in the step of removing the intermediate grating to obtain the slanted grating, the coating material is etched by a chemical solution to remove the intermediate grating 121. The chemical solution has a high selectivity with the filling material and can etch the intermediate grating 121 without etching the slanted grating 151.

[0094] Optionally, in one embodiment, the liquid is a tetramethylhydroxylamine solution (TMAH) or a hydrofluoric acid solution (HF). The tetramethylhydroxylamine solution can be used to remove the silicon material, and the hydrofluoric acid solution can be used to remove the silicon dioxide. The tetramethylhydroxylamine solution and the hydrofluoric acid solution have almost no effect on the filling material, and thus the intermediate grating 121 can be effectively removed, ensuring that the slanted grating 151 with intact morphological features can be obtained.

[0095] For example, Figure 6 As shown, from (a) to (h) are the changes of the substrate during the preparation process of the slant grating, (a) is obtained after steps S111, S112 and S113; (b) is obtained after steps S121 and S122; (c) is obtained after step S123; (d) is obtained after step S124; (e) is obtained after step S125; (f) is obtained after step S200; (g) is obtained after step S300; (e) is obtained after step S400.

[0096] Furthermore, the present application also provides a slant grating, which is prepared by any of the slant grating preparation methods described above.

[0097] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a slanted grating, characterized in that: The method for preparing the slanted grating comprises the following steps: preparing an intermediate grating; filling the gaps between the intermediate gratings with slanted grating materials to obtain an intermediate substrate; performing a planarization process on the intermediate substrate to remove the filling material exceeding the height of the intermediate grating; as well as The intermediate grating is removed to obtain a slanted grating.

2. The method for preparing a slanted grating according to claim 1, wherein: The step of preparing the intermediate grating comprises: coating a coating material onto a base substrate to form a coating layer on the base substrate; and Oblique grating etching is performed on the coating layer to obtain an intermediate grating.

3. The method for preparing a slanted grating according to claim 2, wherein: The step of plating the coating material onto the base substrate to form a coating layer on the base substrate comprises the following steps: preparing a base layer; plating an isolation material onto the base layer to form an isolation layer on the base layer, thereby obtaining the base substrate; and A coating material is plated onto the isolation layer to form a coating layer on the isolation layer.

4. The method for preparing a slanted grating according to claim 2, wherein: The step of performing oblique grating etching on the coating layer to obtain the intermediate grating comprises the following steps: applying a mask material onto the coating layer to form a mask layer on the coating layer; Performing pattern definition on the mask layer to form a mask pattern layer on the mask layer; etching the mask layer through the mask pattern layer to obtain an etched pattern; as well as The coating layer is etched according to the etching pattern to obtain an intermediate grating.

5. The method for preparing a slanted grating according to claim 4, wherein: In the step of etching the mask layer through the mask pattern layer to form an etched pattern, the sum of the width of the ridge of the etched pattern and the width of the ridge of the slanted grating prepared by the slanted grating preparation method is equal to the period of the etched pattern.

6. The method for preparing a slanted grating according to claim 4, wherein: In the step of etching the mask layer through the mask pattern layer to form an etching pattern, the mask layer is dry-etched by using chlorine, oxygen, and argon to obtain the etching pattern.

7. The method for preparing a slanted grating according to claim 2, wherein: The coating material is one or more of silicon dioxide material, amorphous silicon material, and silicon nitride material.

8. The method for preparing a slanted grating according to claim 4, wherein: After the step of etching the coating layer according to the etching pattern to obtain the intermediate grating, the method further includes the following steps: The mask layer is wet-etched to remove the mask layer.

9. The method for preparing a slanted grating according to claim 4, wherein: In the step of etching the coating layer according to the etching pattern to obtain the intermediate grating, one or more of carbon tetrafluoride, octafluorocyclobutane, sulfur hexafluoride and argon are used, and the coating layer is etched using a reactive ion beam etching machine to obtain the intermediate grating.

10. The method for preparing a slanted grating according to any one of claims 1 to 9, wherein: In the step of filling the gaps between the intermediate gratings with the slanted grating material to obtain the intermediate substrate, the gaps between the intermediate gratings with the slanted grating material are filled with the slanted grating material by an atomic layer deposition coating machine.

11. The method for preparing a slanted grating according to claim 10, wherein: The filling material is one or more of titanium dioxide, niobium pentoxide, and aluminum oxide.

12. The method for preparing a slanted grating according to any one of claims 1 to 9, wherein: In the step of performing a planarization process on the intermediate substrate to remove the filling material exceeding the height of the intermediate grating, the intermediate substrate is planarized by a chemical mechanical polishing machine to remove the portion exceeding the intermediate grating.

13. The method for preparing a slanted grating according to any one of claims 1 to 9, wherein: The step of flattening the intermediate substrate to remove the filling material exceeding the height of the intermediate grating and the step of removing the intermediate grating to obtain the slanted grating further includes the following steps: The intermediate substrate after the planarization process is further polished by a chemical mechanical polishing machine to adjust the overall height of the intermediate substrate.

14. The method for preparing a slanted grating according to any one of claims 2 to 9, wherein: In the step of removing the intermediate grating to obtain the slanted grating, the coating material is corroded by a chemical solution to remove the intermediate grating.

15. The method for preparing a slanted grating according to claim 14, wherein: The drug solution is a tetramethylhydroxylamine solution or a hydrofluoric acid solution.

16. A slanted grating, characterized in that: The slant grating is prepared by the slant grating preparation method according to any one of claims 1 to 15.

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