Preparation method of light guide element

Abstract

The embodiment of the invention provides a preparation method of a light guide element. The preparation method of the light guide element comprises the following steps: providing a substrate, wherein the substrate is provided with a first surface and a second surface which are arranged oppositely; depositing a grating dielectric layer on the first surface of the substrate; a functional film is deposited on the second surface of the substrate, and a protective film is arranged on the side, away from the substrate, of the functional film; forming a grating structure on the grating dielectric layer through an etching process and removing etching residues; and removing the protective film to form the light guide element.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of grating technology, and more specifically, the embodiments of the present application relate to a method for preparing a light guide element. Background Art

[0002] In augmented reality (AR) devices, grating structures serve as coupling-in, turning, and out-coupling elements of waveguides. By adjusting the period, line width, and tilt angle, they can achieve precise diffraction and directional propagation of light.

[0003] When manufacturing these gratings with different heights, process steps such as photolithography and etching are used to etch and protect different areas. However, in the current manufacturing process, even the widely used dry stripping technology (such as bombardment with oxygen or argon plasma) and wet stripping methods (including immersion in solutions such as acetone and NMP combined with ultrasonic treatment) are still difficult to completely remove various reaction byproducts remaining inside the grating structure. Therefore, additional cleaning fluids must be introduced to further remove the byproducts and residual photoresist generated during the etching process. However, these additional cleaning fluids often corrode the anti-reflection layer on the back of the diffraction optical waveguide, thereby adversely affecting the performance of the device.

[0004] In view of this, it is necessary to provide a new technical solution to solve the above technical problems. Summary of the invention

[0005] The purpose of this application is to provide a new technical solution for the preparation method of light guide elements.

[0006] The present application provides a method for preparing a light guide element. The method for preparing a light guide element comprises:

[0007] Providing a substrate having a first surface and a second surface disposed opposite to each other;

[0008] Depositing a grating dielectric layer on a first surface of the substrate;

[0009] A functional film is deposited on the second surface of the substrate, and a protective film is provided on the side of the functional film away from the substrate.

[0010] forming a grating structure on the grating dielectric layer by an etching process and removing etching residues;

[0011] The protective film is removed to form a light guide element.

[0012] Optionally, forming a grating structure in the grating medium layer specifically includes:

[0013] Disposing a photoresist on the side of the grating dielectric layer away from the substrate and forming a grating structure through an etching process;

[0014] A cleaning solution containing phenols and / or amines is used to remove etching residues, and the protective film isolates the functional film from the cleaning solution.

[0015] Optionally, the protective film has a thickness greater than 50 μm.

[0016] Optionally, the material of the protective film is a metal material.

[0017] Optionally, the protective film is a first metal mask layer.

[0018] Optionally, providing a protective film on a side of the functional film away from the substrate specifically includes:

[0019] The protective film is deposited on a side of the functional film facing away from the substrate.

[0020] Optionally, removing the protective film to form a grating specifically includes:

[0021] The protective film is removed by a wet etching process.

[0022] Optionally, the material of the functional film is silicon oxide series.

[0023] Optionally, disposing a photoresist on the side of the grating medium layer away from the substrate and forming a grating structure by etching specifically includes:

[0024] Corresponding to different areas of the substrate, grating dielectric layers of different heights are manufactured by dry etching process;

[0025] Depositing a second metal mask layer on the grating dielectric layer at different heights;

[0026] forming a glue mask layer on the second metal mask layer by exposure or nano-imprinting;

[0027] The unmasked area is etched by dry etching process to copy the morphology of the glue mask layer to the grating medium layer.

[0028] Optionally, corresponding to different regions of the substrate, manufacturing grating dielectric layers of different heights by dry etching process specifically includes:

[0029] Using ultraviolet lithography to form masked areas and unmasked areas on the grating dielectric layer;

[0030] The unmasked area is dry-etched.

[0031] Optionally, after removing the remaining photoresist and etching byproducts using a cleaning solution containing phenols and / or amines, the following steps may also be performed:

[0032] The second metal mask layer is removed by a wet etching process.

[0033] According to an embodiment of the present application, a functional film is arranged on the substrate and a protective film is arranged on the side of the functional film facing away from the substrate. When preparing a grating on the substrate, the protective film can isolate the functional film from the cleaning liquid to avoid corrosion of the functional film.

[0034] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0036] Figure 1 Shown is a flow chart of a method for preparing a light guide element provided in an embodiment of the present application.

[0037] Figure 2-Figure 7 Shown is a schematic diagram of the structure of preparing a light-guiding element provided in an embodiment of the present application.

[0038] Description of reference numerals:

[0039] 1. Substrate; 2. Grating dielectric layer; 3. Functional film; 4. Protective film; 5. First photoresist layer; 51. Masked area; 52. Unmasked area; 6. Second photoresist layer; 7. Second metal mask layer; 8. Grating structure. DETAILED DESCRIPTION

[0040] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0041] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0042] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0043] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0044] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0045] The embodiment of the present application provides a method for preparing a light guide element. Exemplarily, the light guide element includes but is not limited to a diffractive optical waveguide.

[0046] The light-guiding element includes a substrate 1 and a grating formed on the substrate 1. The grating can be prepared on the substrate 1 by etching and other processes. The currently used dry degumming methods, such as oxygen and argon plasma bombardment, and wet degumming methods, such as immersion and ultrasonic treatment with solutions such as acetone and NMP, have failed to completely remove the photoresist residue inside the grating structure 8. In addition, etching by-products will inevitably be produced during the etching process, which increases the difficulty of surface cleaning. Although there are specific cleaning solutions such as phenols and amines that can effectively remove etching by-products and residual photoresist for dry etching processes, their side effects cannot be ignored - they will cause corrosive damage to the anti-reflection layer on the back of the substrate 1 and damage the overall structure of the light-guiding element.

[0047] Based on the above technical issues, refer to Figure 1-Figure 7 The embodiment of the present application provides a method for preparing a light-guiding element, which solves the technical problem of corrosion of the functional film 3 (anti-reflection film) by the cleaning liquid.

[0048] Specifically, the light guide element preparation method includes:

[0049] S1: providing a substrate 1, wherein the substrate 1 has a first surface and a second surface disposed opposite to each other;

[0050] S2: depositing a grating dielectric layer 2 on the first surface of the substrate 1;

[0051] S3: depositing a functional film 3 on the second surface of the substrate 1, and providing a protective film 4 on the side of the functional film 3 away from the substrate 1;

[0052] S4: forming a grating structure 8 on the grating dielectric layer 2 by an etching process and removing etching residues;

[0053] S5: removing the protective film 4 to form a light guide element.

[0054] In step S1, refer to Figure 1 and Figure 2 , a substrate 1 of a light guide element is provided, and the substrate 1 is a substrate 1 with a high refractive index. Exemplarily, the material of the substrate 1 can be high refractive index glass or lithium niobate.

[0055] The substrate 1 generally has a first surface and a second surface disposed opposite to each other, the first surface being the front side of the substrate 1, and the second surface being the back side of the substrate 1. The first surface and the second surface will be used to deposit different film layers in subsequent steps.

[0056] Exemplarily, the substrate 1 may be a cubic structure.

[0057] In step S2, refer to Figure 2 On the first surface (front side) of the substrate 1, a grating dielectric layer 2 is formed by a deposition process (such as sputtering, evaporation or chemical vapor deposition). This dielectric layer will be processed into a grating structure 8 in a subsequent step to achieve a specific optical function. Exemplarily, the material of the grating dielectric layer 2 includes but is not limited to titanium oxide, silicon carbide, etc.

[0058] In step S3, please continue to refer to Figure 2 , a functional film 3, such as an anti-reflection film, is deposited on the second surface (reverse side) of the substrate 1 to enhance the optical performance of the light-guiding element.

[0059] On the side of the functional film 3 facing away from the substrate 1, an additional protective film 4 is provided. The main function of the protective film 4 is to prevent the cleaning liquid from corroding or damaging the functional film 3 in the subsequent degumming step.

[0060] In step S4, refer to Figure 3a-Figure 6b An etching process (such as wet etching or dry etching) is used to form a grating structure 8 on the grating medium layer 2. Parameters such as the shape, size and spacing of the grating structure 8 will directly affect the optical performance of the light guide element.

[0061] After the etching is completed, it is necessary to remove the residues generated during the etching process, such as etching solution residues, etching byproducts, etc. This step is crucial to ensure the clarity and optical performance of the grating structure 8 .

[0062] In step S3, a protective film 4 is provided on the side of the functional film 3 facing away from the substrate 1. When it comes to step S4, when it is necessary to remove various residues left over from the etching process, such as etching liquid residues and etching byproducts, this protective film 4 effectively isolates the functional film 3 from the cleaning liquid, thereby preventing the cleaning liquid from causing possible corrosion damage to the functional film 3. Such a design not only ensures that the functional film 3 is intact, but also further improves the overall quality and performance of the light guide element.

[0063] In step S5, refer to Figure 7 After the grating structure 8 is prepared, the protective film 4 previously disposed on the functional film 3 is removed. This step is usually achieved by chemical dissolution, mechanical stripping, etching or other appropriate film removal processes, wherein the selection of the film removal process is mainly related to the setting method of the protective film 4 and / or the material of the protective film 4. After removing the protective film 4, the final light guide element is obtained.

[0064] The light guide element preparation method provided in the embodiment of the present application effectively avoids the problem of corrosion of the functional film 3 by the cleaning liquid by providing the protective film 4. This method not only improves the optical performance of the light guide element, but also ensures the integrity and stability of its structure. At the same time, the preparation method has the advantages of simple process, easy implementation and low cost, and is suitable for large-scale industrial production.

[0065] In one embodiment, referring to Figure 3a-Figure 6b The forming of the grating structure 8 on the grating medium layer 2 specifically includes:

[0066] Disposing a photoresist on the side of the grating medium layer 2 away from the substrate 1 and forming a grating structure 8 through an etching process;

[0067] A cleaning solution containing phenols and / or amines is used to remove etching residues, and the protective film 4 isolates the functional film 3 from the cleaning solution.

[0068] In this embodiment, the formation process of the grating structure 8 and the subsequent removal process of the residues are defined.

[0069] First, a layer of photoresist can be disposed on the side of the grating dielectric layer 2 facing away from the substrate 1 by coating or the like. This layer of photoresist will act as a mask in the subsequent etching process so as to form the desired grating structure 8 on the grating dielectric layer 2 .

[0070] Next, the grating dielectric layer 2 is etched according to the pattern of the photoresist using a specific etching process, thereby forming a clear grating structure 8 on the grating dielectric layer 2. This step determines key parameters of the grating structure 8 such as shape, size and distribution.

[0071] After the etching process is completed, we need to remove various residues generated during the etching process, including photoresist residues and by-products generated by the etching reaction. In order to effectively complete this step, a cleaning solution containing phenols and / or amines can be used. These cleaning solutions can effectively dissolve and remove photoresist and etching residues, thereby ensuring the clarity and neatness of the grating structure 8.

[0072] However, in the process of removing these residues, we paid special attention to the potential corrosion risk caused by the cleaning liquid to the functional membrane 3. In order to solve this problem, we pre-set a protective film 4 on the functional membrane 3 to completely isolate the functional membrane 3 from the cleaning liquid, thereby effectively preventing any corrosion damage to the functional membrane 3 by the cleaning liquid.

[0073] For example, the cleaning liquid containing phenols may be a phenol cleaning liquid, a phenolic resin solution, etc., and the cleaning liquid containing amines may be various amino compounds, such as ethylamine, propylamine, etc. The cleaning liquid containing phenols and amines is a composite cleaning liquid.

[0074] It should be noted that the composite cleaning solution contains both phenolic and amine components. These composite cleaning solutions combine the advantages of phenolic (like dissolves like) and amine (amine compounds can react chemically with certain components in the photoresist, thereby dissolving or decomposing them), and have faster removal speeds and better removal effects.

[0075] In one embodiment, the thickness of the protective film 4 is greater than 50 μm.

[0076] In this embodiment, the thickness of the protective film 4 is limited. A thicker protective film 4 can more effectively isolate harmful chemicals such as cleaning fluid, thereby fully protecting the underlying functional film 3 from corrosion or damage.

[0077] By adopting the protective film 4 of such thickness, the safety and reliability of the light guide element during the preparation process are ensured.

[0078] It is worth noting that the specific thickness of the protective film 4 can be fine-tuned according to the actual application scenario and process requirements. In some cases, a thicker protective film 4 can be selected to provide a stronger protective effect; in other cases, in order to optimize the overall performance and reduce costs, a slightly thinner protective film 4 that can also meet the protection requirements can be selected. Preferably, the thickness of the protective film 4 is generally 100μm to 300μm.

[0079] In a specific embodiment, the material of the protective film 4 is a metal material.

[0080] In this embodiment, the material of the protection film 4 is limited to a metal material, mainly to facilitate the formation and removal of the protection film 4 .

[0081] Specifically, when forming the grating structure 8 on the first surface of the substrate 1, it is necessary to use a metal film as a part of the mask. In this case, the protective film 4 can be provided on the side of the functional film 3 away from the substrate 1 by using the process of making the metal mask. More conveniently, when forming the grating structure 8 on the first surface of the substrate 1, it is also necessary to remove the metal mask. In this case, the metal mask for making the grating structure 8 and the protective film 4 can be removed at the same time, saving the process flow.

[0082] For example, the material of the protective film 4 may also be a rubber material (such as silicone rubber, etc.) or a plastic material. The protective film 4 of the rubber material or the protective film 4 of the plastic material may also isolate the functional film 3 from the cleaning liquid, thereby protecting the functional film 3. For example, the material of the protective film 4 may also be PC, PET, etc.

[0083] When the material of the protective film 4 is a rubber material, it can be formed on one side of the functional film 3 by spraying or the like. When the material of the protective film 4 is a plastic material, it can be formed on one side of the functional film 3 by calendaring or thermoforming, as long as the functional film 3 is not damaged. In addition, the protective film 4 can be removed by using a method suitable for removing rubber or plastic, as long as the functional film 3, the substrate 1 and the grating structure 8 are not damaged.

[0084] Specifically, the protection film 4 is a first metal mask layer, and the first metal mask layer includes but is not limited to metals such as Mo and Cr.

[0085] Exemplarily, the first metal mask layer covers the functional film 3 area to be protected, effectively preventing harmful chemicals such as cleaning fluid from corroding the functional film 3. At the same time, due to the compatibility of the metal mask with the cleaning fluid and other process steps, this design simplifies the process flow and improves production efficiency.

[0086] When the protective film 4 is a first metal mask layer, a specific method of arranging the first metal mask layer on the side of the functional film 3 away from the substrate 1 is: depositing the first metal mask layer on the side of the functional film 3 away from the substrate 1 .

[0087] Specifically, the first metal mask layer is formed on the side of the functional film 3 away from the substrate 1 by physical vapor deposition (such as sputtering deposition, evaporation deposition, etc.) or chemical vapor deposition, etc. The specific deposition method selected depends on factors such as the material of the metal mask layer, the required performance and the availability of process equipment.

[0088] The first metal mask layer is deposited on the functional film 3 , which protects the underlying functional film 3 from being corroded by harmful chemicals such as cleaning fluid.

[0089] In the case where the protective film 4 is a first metal mask layer, a specific method of removing the first metal mask layer to form a grating is: removing the first metal mask layer by a wet etching process.

[0090] Specifically, the wet etching process usually has good selectivity to the metal mask layer and the substrate 1 material, and can effectively remove the metal mask layer without damaging the substrate 1 .

[0091] In a specific embodiment, the material of the functional film 3 is silicon oxide system.

[0092] In this embodiment, the material of the functional film 3 is silicon oxide-based, and the silicon oxide-based materials mainly include various compounds and mixtures based on silicon oxide (SiO 2 ).

[0093] For example, silicon dioxide (SiO2) has a low refractive index (about 1.45) and excellent transparency, and is one of the most commonly used materials in AR anti-reflection films. It can be used to prepare single-layer or multi-layer AR coatings.

[0094] In a specific embodiment, disposing a photoresist on the side of the grating medium layer 2 away from the substrate 1 and forming the grating structure 8 by etching specifically includes:

[0095] Reference Figure 3a-3d , corresponding to different areas of the substrate 1, manufacturing grating dielectric layers 2 of different heights by dry etching process;

[0096] Reference Figure 4 , depositing a second metal mask layer 7 on the grating dielectric layer 2 at different heights;

[0097] Reference Figure 5 , forming a glue mask layer on the second metal mask layer 7 by exposure or nano-imprinting;

[0098] Reference Figure 6a-6b , the morphology of the resist mask layer is copied to the grating medium layer 2 through a dry etching process.

[0099] Specifically, first, refer to Figure 3a-Figure 3b On the substrate 1, a grating dielectric layer 2 is formed by deposition, and regions of different heights are produced on the grating dielectric layer 2 by a dry etching process (such as reactive ion etching, plasma etching, etc.) so as to form grating structures 8 of different heights in subsequent steps.

[0100] In a specific embodiment, referring to Figure 3a-3d The method of manufacturing the grating dielectric layer 2 with different heights by dry etching process specifically includes:

[0101] Using ultraviolet lithography to form masked areas and unmasked areas on the grating medium layer 2;

[0102] The unmasked area is dry-etched.

[0103] Reference Figure 3a , a first photoresist layer 5 is disposed on the side of the grating dielectric layer 2 facing away from the substrate 1, and a masked area 51 and an unmasked area 52 are formed by ultraviolet photolithography;

[0104] Reference Figure 3b ,right Figure 3a The unmasked area 52 is etched, and the height of the unmasked area 52 is lower than the height of the masked area 51.

[0105] Reference Figure 3c ,right Figure 3bThe first photoresist layer 5 is re-disposed on the side of the grating dielectric layer 2 with a new structure facing away from the substrate 1, and the masked area 51 and the unmasked area 52 are formed again by ultraviolet photolithography.

[0106] Reference Figure 3d ,right Figure 3c The unmasked area 52 is etched, and the height of the unmasked area 52 is lower than the height of the masked area 51.

[0107] In this way, after multiple UV lithography and etching, grating medium layers 2 with different heights are manufactured.

[0108] It should be noted that after etching the unmasked area 52, the substrate 1 needs to be immersed in a cleaning solution to remove excess photoresist and etching by-products, and the protective film 4 arranged on one side of the functional film 3 isolates the functional film 3 from the cleaning solution to prevent the functional film 3 from being corroded.

[0109] Exemplarily, the first photoresist layer 5 is ultraviolet photoresist.

[0110] Next, refer to Figure 4 , a second metal mask layer 7 is deposited on the grating dielectric layer 2 at different heights. The material of the second metal mask layer 7 and the first metal mask layer mentioned above may be the same or different.

[0111] In the case that the second metal mask layer 7 and the first metal mask layer are made of the same material, the first metal mask layer and the second metal mask layer 7 may be removed simultaneously in a subsequent removal process.

[0112] Then, refer to Figure 5 , depositing a second photoresist layer 6 on the second metal mask layer 7, and manufacturing a photoresist mask layer on the substrate surface by exposure or nano-imprinting.

[0113] Exemplarily, the second photoresist layer 6 may be electron beam photoresist or nano-imprint resist.

[0114] Finally, refer to Figure 6a-6b , the structure of the glue mask layer is first copied to the second metal mask layer 7 through an etching process, and then the structure of the glue mask layer is copied to the grating medium layer 2 to form a grating structure 8.

[0115] In one embodiment, referring to Figure 7 After removing the etching residues by using a cleaning solution containing phenols and / or amines, the method further includes: removing the second metal mask layer 7 by using a wet etching process.

[0116] Specifically, when the second metal mask layer 7 and the first metal mask layer appearing above are made of the same material, the second metal mask layer 7 and the first metal mask layer are removed by wet etching to form a light guide element.

[0117] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0118] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A method for preparing a light guide element, characterized in that: include: Providing a substrate having a first surface and a second surface disposed opposite to each other; Depositing a grating dielectric layer on a first surface of the substrate; Depositing a functional film on the second surface of the substrate, and providing a protective film on the side of the functional film away from the substrate; forming a grating structure on the grating dielectric layer by an etching process and removing etching residues; The protective film is removed to form a light guide element.

2. The method for preparing a light guide element according to claim 1, characterized in that: Forming a grating structure on the grating dielectric layer by an etching process and removing etching residues specifically includes: Disposing a photoresist on the side of the grating dielectric layer away from the substrate and forming a grating structure through an etching process; A cleaning solution containing phenols and / or amines is used to remove etching residues, and the protective film isolates the functional film from the cleaning solution.

3. The method for preparing a light guide element according to claim 1, characterized in that: The thickness of the protective film is greater than 50 μm.

4. The method for preparing a light guide element according to claim 1, characterized in that: The material of the protective film is metal material.

5. The method for preparing a light guide element according to claim 1, characterized in that: The protection film is a first metal mask layer.

6. The method for preparing a light guide element according to claim 4, characterized in that: Providing a protective film on the side of the functional film away from the substrate specifically includes: The protective film is deposited on a side of the functional film facing away from the substrate.

7. The method for preparing a light guide element according to claim 4, characterized in that: Removing the protective film to form a grating specifically includes: The protective film is removed by a wet etching process.

8. The method for preparing a light guide element according to any one of claims 1 to 7, characterized in that: The material of the functional film is silicon oxide series.

9. The method for preparing a light guide element according to claim 2, characterized in that: Disposing a photoresist on the side of the grating medium layer away from the substrate and forming a grating structure by etching specifically includes: Corresponding to different areas of the substrate, grating dielectric layers of different heights are manufactured by dry etching process; Depositing a second metal mask layer on the grating dielectric layer at different heights; forming a glue mask layer on the second metal mask layer by exposure or nano-imprinting; The unmasked area is etched by dry etching process to copy the morphology of the glue mask layer to the grating medium layer.

10. The method for preparing a light guide element according to claim 9, characterized in that: Corresponding to different areas of the substrate, grating dielectric layers of different heights are manufactured by dry etching process, specifically including: Using ultraviolet lithography to form masked areas and unmasked areas on the grating dielectric layer; The unmasked area is dry-etched.

11. The method for preparing a light guide element according to claim 9, characterized in that: After using a cleaning solution containing phenols and / or amines to remove etching residues, the following steps are also included: The second metal mask layer is removed by a wet etching process.

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