A waveguide lens with a bevel type nanostructure and a manufacturing method thereof

Abstract

The application discloses a manufacturing method of a waveguide lens with inclined surface nanostructure, and relates to the technical field of waveguide lenses, in particular to a manufacturing method of a waveguide lens with inclined surface nanostructure. The method comprises the following steps: providing a waveguide substrate; preparing a photoresist layer on the surface of the waveguide substrate; selecting at least two regions on the surface of the photoresist layer and performing pattern processing on the regions to obtain a patterned photoresist and a patterned groove; forming a covering layer on the patterned photoresist and the surface of the patterned groove which is not covered by the patterned photoresist by adopting a shadow plating method; forming a plurality of inclined surface nanostructures on the waveguide substrate by adopting a forward or slightly inclined etching method; and removing the remaining covering layer and the photoresist layer. The application further discloses a waveguide lens with inclined surface nanostructure, which is manufactured by using the above manufacturing method of the waveguide lens with inclined surface nanostructure. The method etches the uncovered part of the region and the covering layer at the same time, realizes the preparation of the inclined surface nanostructure, reduces the preparation difficulty, and has high controllability.

Description

Technical Field

[0001] This invention relates to the field of augmented reality display technology, and in particular to a waveguide lens with a beveled nanostructure and its fabrication method. Background Technology

[0002] Augmented Reality (AR) technology is a new technology that seamlessly integrates real-world and virtual-world information. It not only displays real-world information but also simultaneously shows virtual information, with the two types of information complementing and overlaying each other. In visual augmented reality, users use head-mounted displays to superimpose the real world with computer graphics, allowing them to see the real world surrounding them. Currently, most mainstream near-eye augmented reality display devices utilize the principle of optical waveguides. Tilted diffraction gratings have a higher first-order diffraction efficiency and reduce the zero-order component, thereby improving display brightness while further reducing image dispersion.

[0003] To fabricate tilted nanostructures on waveguide surfaces, researchers have proposed methods such as tilted etching of photoresist structures, tilted etching of metal masks, and hybrid wet-dry etching. However, in existing technologies, the tilt angle of the tilted groove surface depends entirely on the tilt angle of the ion beam. Tilted etching with a tilted ion beam is a technical challenge, as it is inherently difficult to control and involves high costs for tilting equipment. If tilted etching of photoresist structures is used directly, problems such as insufficient etching angle and etching rate ratio arise. Hybrid wet-dry etching also faces the same issues, and it cannot precisely control the contour depth, resulting in large processing errors and low controllability.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a waveguide lens with a slanted nanostructure that is easy to prepare and highly controllable, and a method for preparing the same.

[0006] This invention provides a method for fabricating a waveguide lens with a beveled nanostructure, the method comprising:

[0007] Provide a waveguide substrate;

[0008] A photoresist layer is prepared on the surface of the waveguide substrate;

[0009] At least two regions are selected on the surface of the photoresist layer, and the regions are patterned to obtain patterned photoresist and patterned grooves exposing the surface of the waveguide substrate.

[0010] A coating is formed on the patterned photoresist and on the surfaces at the bottom of the patterned groove that are not covered by the patterned photoresist;

[0011] The waveguide substrate and the capping layer are etched using forward or micro-tilt etching methods, or the waveguide substrate, the capping layer and the patterned photoresist are etched.

[0012] The remaining capping layer and photoresist layer are removed to obtain a sloped nanostructure that is integrated with the waveguide substrate.

[0013] In one embodiment, in the step of preparing a photoresist layer, the photoresist layer is formed by spin coating, spraying, or blade coating on the surface of the waveguide substrate.

[0014] In one embodiment, the patterning process involves using interference lithography, holographic exposure, or overlay technology on the photoresist layer to form the patterned photoresist and the patterned grooves on the waveguide substrate.

[0015] In one embodiment, during the step of forming the cover layer, the tilt angle and deposition rate of the coating are adjusted according to the morphology requirements of the cover layer, and the cover layer is formed on the top surface and side surface of the patterned photoresist and on the surface at the bottom of the patterned groove that is not shaded by the adjacent patterned photoresist, wherein the portion of the cover layer covering the side surface is in the form of a continuous slope or a stepped shape.

[0016] In one embodiment, the cover layer is made of a material with an etching rate similar to that of the waveguide substrate.

[0017] In one embodiment, during the step of forming multiple beveled nanostructures, the bottom portion of the patterned groove not covered by the capping layer is etched simultaneously with the capping layer, and the difference between the etching depth of the bottom portion of the patterned groove not covered by the capping layer and the etching depth of the capping layer depends on the etching rate ratio of the waveguide substrate to the capping layer.

[0018] The present invention also provides a waveguide lens with a beveled nanostructure, comprising a waveguide substrate, wherein at least two regions are provided on the surface of the waveguide substrate, each region comprising a plurality of the beveled nanostructures, and the beveled nanostructures are fabricated using the above-described method for fabricating a waveguide lens with a beveled nanostructure.

[0019] In one embodiment, the tilt angles and depths of multiple inclined nanostructures in the same region are the same, while the tilt angles and depths of the inclined nanostructures in different regions may be the same or different.

[0020] In one embodiment, a plurality of the sloped nanostructures form a grating structure or a lattice structure.

[0021] In one embodiment, one side of the inclined nanostructure is a continuous inclined surface or a stepped surface.

[0022] The method for fabricating a waveguide lens with a beveled nanostructure provided by the present invention involves simultaneously etching the portion of the region not covered by the cover layer and the cover layer using a tilted etching method, thereby forming multiple beveled nanostructures in the region. The cover layer is used as an etching mask to realize the fabrication of the beveled nanostructures. Conventional etching materials are used, reducing the fabrication difficulty and providing high controllability. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the steps of a method for fabricating a waveguide lens with a beveled nanostructure according to an embodiment of the present invention.

[0024] Figures 2a to 2d This is a process flow diagram of the fabrication method of the waveguide lens with the inclined nanostructure of the present invention;

[0025] Figure 3 This is a schematic diagram of the structure with a stepped capping layer prepared in step S4 in an embodiment of the present invention;

[0026] Figure 4 for Figure 3 A schematic diagram of the stepped, inclined nanostructure formed after etching;

[0027] Figure 5 for Figure 2b A schematic diagram of the inclined nanostructure formed after micro-tilting ion beam etching on both sides;

[0028] Figure 6 This is a schematic diagram of the waveguide lens with a beveled nanostructure according to an embodiment of the present invention;

[0029] Figure 7 for Figure 6 The magnified 3D image at point A in the middle. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] Please refer to Figures 1 to 5 The method for fabricating a waveguide lens with a beveled nanostructure provided in this embodiment of the invention includes:

[0032] S1: Provide a waveguide substrate 1;

[0033] S2: A photoresist layer is prepared on the surface of waveguide substrate 1;

[0034] S3: Select at least two regions on the surface of the photoresist layer and pattern the regions to obtain patterned photoresist 21 and patterned grooves 22 on the surface of the exposed waveguide substrate 1.

[0035] S4: Coating, forming a cover layer 31 on the patterned photoresist 21 and on the surface of the bottom of the patterned groove 22 that is not covered by the patterned photoresist 21;

[0036] S5: Etch the waveguide substrate 1 and the capping layer, or the waveguide substrate, the capping layer and the patterned photoresist 21, using forward or micro-tilt etching.

[0037] S6: Remove the remaining capping layer 31 and patterned photoresist 21 to obtain a sloping nanostructure 71 integrated with the waveguide substrate 1.

[0038] In this embodiment, the waveguide substrate 1 is made of a material with high visible light transparency, which enables total internal reflection of image light within the waveguide substrate 1, and its refractive index is not less than 1.4. Specifically, the waveguide substrate 1 can be made of glass or resin.

[0039] In step S2, a photoresist layer is formed by coating one side surface of the waveguide substrate 1 with a layer of photoresist using spin coating, spray coating, or scraping coating.

[0040] Specifically, photoresist is applied to the entire surface of one side of the waveguide substrate 1 using a scraping method. The refractive index of the photoresist is between 1.4 and 1.8.

[0041] In step S3, the patterning process involves using interference lithography, holographic exposure, or overlay technology on the photoresist layer to form patterned photoresist 21 and patterned grooves 22 on the waveguide substrate 1.

[0042] Specifically, the photoresist layer is exposed and developed according to the desired pattern to obtain a patterned photoresist 21 with the desired pattern morphology in the selected area, as well as a patterned groove 22 exposing the surface of the waveguide substrate 1 (i.e., the bottom of the patterned groove 22 is the exposed surface of the waveguide substrate 1). To ensure that the exposed part and the parts outside the area are cleaner, oxygen ion bombardment can be performed by equipment such as a plasma stripper after exposure and development.

[0043] It should be noted that during patterning, the entire photoresist layer can be processed to simultaneously form patterned photoresist 21 and patterned grooves 22 in at least two selected areas; alternatively, the selected areas can be processed sequentially to obtain patterned photoresist 21 and patterned grooves 21 in their respective areas.

[0044] In step S4, the capping layer 31 is made of a material with an etching rate similar to that of the waveguide substrate 1. Specifically, the etching rate of the waveguide substrate 1 is equal to or close to the etching rate of the capping layer 31 to ensure the etching depth of the waveguide substrate 1 and the required etched pattern. Preferably, the capping layer 31 is made of silicon dioxide, silicon nitride, or titanium dioxide, etc.

[0045] The coating process begins from left to right or right to left. Thus, the capping layer 31 covers the top surface of the raised patterned photoresist 21, the side surface of one side of the patterned photoresist 21, and the bottom portion of the patterned groove 22 not covered by the patterned photoresist 21, thereby giving the capping layer 31 multiple beveled surfaces (as shown in Figure 2). Specifically, by adjusting the tilt angle and coating rate during coating according to the morphology of the capping layer 31, the morphology and tilt angle of the portion of the capping layer 31 covering the side surface of the patterned photoresist 21 can be changed, such as forming a beveled surface... Figure 2b The continuously inclined surface shown may be Figure 3 The step-shaped shape shown.

[0046] In step S5, etching is performed using forward etching (i.e., vertical etching) or micro-tilt etching. During etching, the area not covered by the capping layer 31 (i.e., the surface of the uncovered waveguide substrate 1) is etched simultaneously with the capping layer 31. The difference between the etching depth at the bottom of the part of the patterned groove 22 not covered by the capping layer 31 and the etching depth of the capping layer 31 depends on the etching rate ratio between the waveguide substrate 1 and the capping layer 31.

[0047] Specifically, after a certain etching time, such as Figure 3 The stepped capping layer 33 shown can be etched into the shape of... Figure 4 The illustrated is a stepped, sloping nanostructure 72. (Example:) Figure 2b The capping layer 31 shown has a continuously tilted surface and can be etched as follows: Figure 7 The inclined nanostructure 71 shown has a continuous inclined surface.

[0048] If the profiles of both sides of the inclined nanostructure 71 are required, they can be etched using a micro-tilting ion beam, such as... Figure 2b The capping layer 31 with a continuously inclined surface shown is etched as... Figure 5 The shown is a sloping nanostructure 73 with tilted sides.

[0049] Due to the oblique etching, the ion oblique bombardment, and the shielding effect caused by the superposition height of the patterned photoresist 21 and the capping layer 31, it is beneficial to fabricate oblique nanostructures with relatively small groove widths.

[0050] In step S5, the remaining capping layer 31 and patterned photoresist 21 are removed by solution method in conjunction with microwave plasma machine or the like.

[0051] Please refer to Figures 1 to 5 The present invention also provides a waveguide lens with a beveled nanostructure, comprising a waveguide substrate 1, wherein at least two regions are provided on the surface of the waveguide substrate 1, each region comprising a plurality of beveled nanostructures 71. The beveled nanostructures 71 are fabricated using the above-described method for fabricating a waveguide lens with a beveled nanostructure.

[0052] In this embodiment, two regions are provided on the same side surface of the waveguide substrate 1; the two regions are a coupling region 51 for coupling image light into the waveguide substrate, and a coupling region 53 for coupling image light out to the human eye after total internal reflection by the waveguide substrate 1.

[0053] In other embodiments, a region is provided on each of the two side surfaces of the waveguide substrate 1.

[0054] Multiple inclined nanostructures 71 in the same region have the same tilt angle and depth, while the inclined nanostructures 71 in different regions may have the same or different tilt angles and depths. Multiple inclined nanostructures 71 form a grating structure or a lattice structure.

[0055] Multiple inclined nanostructures 71 in the same region have the same tilt angle and depth, while the inclined nanostructures 71 in different regions may have the same or different tilt angle and depth. That is, multiple inclined nanostructures 71 in the coupling region 51 have the same tilt angle and depth; the inclined nanostructures 71 in the coupling region 51 and the coupling region 53 may have the same or different tilt angle and depth.

[0056] Multiple inclined nanostructures 71 form a grating structure or a lattice structure.

[0057] In the accompanying drawings, the dimensions and relative dimensions of layers and regions are exaggerated for clarity. It should be understood that when an element, such as a layer, region, or substrate, is referred to as "formed on," "disposed on," or "located on" another element, the element may be directly disposed on said other element, or there may be intermediate elements present. Conversely, when an element is referred to as "directly formed on" or "directly disposed on" another element, there are no intermediate elements.

[0058] In this document, the terms "upper," "lower," "front," "back," "left," "right," "top," "bottom," "inner," "outer," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used for the clarity of expressing the technical solution and for the convenience of description, and therefore should not be construed as limiting the present invention.

[0059] In this document, unless otherwise stated, “multiple” or “several” means two or more.

[0060] In this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for fabricating a waveguide lens with a beveled nanostructure, characterized in that, The method includes: Provide a waveguide substrate; A photoresist layer is prepared on the surface of the waveguide substrate; At least two regions are selected on the surface of the photoresist layer, and the regions are patterned to obtain patterned photoresist and patterned grooves exposing the surface of the waveguide substrate. A coating is formed on the patterned photoresist and on the surfaces of the bottom of the patterned groove that are not covered by the patterned photoresist. The coating covers the top surface of the raised patterned photoresist, the side surface of one side of the patterned photoresist, and a portion of the bottom of the patterned groove that is not covered by the patterned photoresist, thereby giving the coating a plurality of beveled surfaces. The waveguide substrate and the capping layer are etched using forward or micro-tilt etching methods, or the waveguide substrate, the capping layer and the patterned photoresist are etched. The remaining capping layer and photoresist layer are removed to obtain a sloped nanostructure that is integrated with the waveguide substrate.

2. The method for fabricating a waveguide lens with a beveled nanostructure as described in claim 1, characterized in that, In the step of preparing a photoresist layer, the photoresist layer is formed by spin coating, spraying, or blade coating on the surface of the waveguide substrate.

3. The method for fabricating a waveguide lens with a beveled nanostructure as described in claim 1, characterized in that, The patterning process involves using interference lithography, holographic exposure, or overlay techniques on the photoresist layer to form the patterned photoresist and the patterned grooves on the waveguide substrate.

4. The method for fabricating a waveguide lens with a beveled nanostructure as described in claim 1, characterized in that, In the step of forming the cover layer, the tilt angle and deposition rate of the coating are adjusted according to the morphology requirements of the cover layer. The cover layer is formed on the top surface and side surface of the patterned photoresist and on the surface at the bottom of the patterned groove that is not shaded by the adjacent patterned photoresist. The portion of the cover layer covering the side surface is in the form of a continuous slope or a stepped shape.

5. The method for fabricating a waveguide lens with a beveled nanostructure as described in claim 1, characterized in that, The material of the cover layer is a material with an etching rate similar to that of the waveguide substrate.

6. The method for fabricating a waveguide lens with a beveled nanostructure as described in claim 1, characterized in that, In the step of forming multiple beveled nanostructures, the bottom of the portion of the patterned groove not covered by the capping layer is etched simultaneously with the capping layer. The difference between the etching depth of the bottom of the portion of the patterned groove not covered by the capping layer and the etching depth of the capping layer depends on the etching rate ratio of the waveguide substrate to the capping layer.

7. A waveguide lens with a beveled nanostructure, characterized in that, The device includes a waveguide substrate, on the surface of which at least two regions are provided, each region including a plurality of the aforementioned beveled nanostructures, wherein the beveled nanostructures are fabricated using the waveguide lens fabrication method with beveled nanostructures as described in any one of claims 1 to 6.

8. The waveguide lens with a beveled nanostructure as described in claim 7, characterized in that, Multiple inclined nanostructures in the same region have the same tilt angle and depth, while the inclined nanostructures in different regions may have the same or different tilt angles and depths.

9. The waveguide lens with a beveled nanostructure as described in claim 7, characterized in that, Multiple of the aforementioned inclined nanostructures form a grating structure or a lattice structure.

10. The waveguide lens with a beveled nanostructure as described in claim 7, characterized in that, The sloped nanostructure has a continuous slope or stepped surface on one side.

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