A method for manufacturing a high refractive index blazed grating

Abstract

The application provides a manufacturing method of a high-refractive-index slanted grating, comprising the following steps: S1, forming a seed layer pattern on a grating substrate, the seed layer pattern is a plurality of periodically and spaced lines; and S2, depositing a layer of slanted grating structure material on the seed layer pattern by using a glancing angle deposition technology. The glancing angle deposition technology (GLAD) is used for manufacturing the high-refractive-index slanted grating.

Description

Technical Field

[0001] This invention belongs to the field of optical element technology, and in particular relates to a method for manufacturing a high refractive index oblique tooth grating. Background Technology

[0002] A serrated grating is a high-performance optical element with a periodic spatial structure. Because serrated gratings typically exhibit high efficiency at specific diffraction orders, their primary function is to couple light into optical waveguides. The superior optical performance of serrated gratings makes them widely used in aerospace, telecommunications, spectroscopy, and the rapidly developing fields of virtual reality (VR) and augmented reality (AR). High-refractive-index serrated gratings can provide a wider viewing angle and are an important component in AR glasses.

[0003] Existing methods for fabricating helical toothed gratings include reactive ion etching (RIE) using Faraday cages and a combination of ion beam etching and RIE to achieve the helical toothed grating structure. RIE using Faraday cages requires specific equipment and is only suitable for batch processing of small-scale helical toothed gratings. Combining ion beam etching with RIE can achieve large-scale helical toothed grating structures, but the operation is complex. These two methods are widely used in fabricating gratings made of conventional materials such as silicon dioxide (n=1.5) helical toothed gratings; however, due to the limitations of the etching methods, they are difficult to apply to certain high-refractive-index materials.

[0004] In recent years, nanoimprinting has been proposed as a method for large-scale manufacturing of high-refractive-index helical gratings. This method achieves high refractive index by filling resin with high-refractive-index nanoparticles, such as titanium dioxide (TiO2). Mass production is then achieved through nanoimprinting. However, this approach requires strict control over the degree of nanoparticle filling, and the imprinting template has a limited lifespan; defects may also occur during pattern transfer. Summary of the Invention

[0005] The present invention aims to solve the following technical problems: In the prior art, the methods for manufacturing oblique tooth gratings that use Faraday cages for reactive ion etching and ion beam etching and reactive ion beam etching to realize oblique tooth grating structures are difficult to apply to certain high refractive index materials. The method for manufacturing oblique tooth gratings with high refractive index oblique tooth grating structures using nanoimprinting requires strict control of the degree of nanoparticle filling, and the imprinting template also has a corresponding lifespan, and there may be certain defects in the pattern transfer process.

[0006] This invention provides a method for manufacturing a high-refractive-index oblique tooth grating, which can avoid various technical problems caused by etching the corresponding materials.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for manufacturing a high-refractive-index oblique toothed grating includes:

[0009] S1, a seed layer pattern is formed on the grating substrate. The seed layer pattern consists of several periodically spaced lines.

[0010] S2, a layer of oblique tooth grating structure material is deposited on the seed layer pattern using grazing angle deposition technology.

[0011] As a preferred technical solution, step S1 specifically includes:

[0012] a101, spin-coating an electron beam resist onto the grating substrate;

[0013] a102, using electron beam exposure to form a design pattern on an electron beam resist layer;

[0014] a103, after exposure, is developed at room temperature;

[0015] a104 uses reactive ion etching to transfer the design pattern on the electron beam resist layer to the grating substrate, forming a seed layer pattern;

[0016] a105 utilizes plasma to remove residual electron beam resist.

[0017] As a preferred technical solution, step S1 specifically includes:

[0018] b101, spin-coating a layer of imprinting material onto the grating substrate;

[0019] b102, using an imprinting template to perform nanoimprinting on the imprinting material to form lines with several periodic intervals;

[0020] b103, using plasma to remove the embossing material until the embossing material between the lines is removed, thus obtaining the embossed pattern;

[0021] b104 uses reactive ion etching to transfer the design pattern on the imprinted pattern to the grating substrate to form a seed layer pattern;

[0022] b105 uses plasma to remove residual imprint material.

[0023] As a preferred technical solution, step S1 specifically includes:

[0024] c101, spin-coating a layer of imprinting material onto the grating substrate;

[0025] c102, using an imprinting template to perform nanoimprinting on the imprinting material to form lines with several periodic intervals;

[0026] c103 uses plasma to remove the imprinting material until the imprinting material between the lines is removed, thus obtaining a seed layer pattern.

[0027] As a preferred technical solution, quartz glass is selected as the grating substrate, ZEP520A diluted 1:1 with anisole is selected as the electron beam resist, and TiO2 is selected as the oblique tooth grating structure material.

[0028] As a preferred technical solution, quartz glass is selected as the grating substrate, polystyrene is selected as the imprinting material, the nanoimprinting method is thermal nanoimprinting, and HfO2 and SiO2 are selected as the oblique tooth grating structure materials.

[0029] As a preferred technical solution, polyethylene terephthalate is selected as the grating substrate, ultraviolet nanoimprint adhesive is used as the imprinting material, ultraviolet nanoimprinting is used as the nanoimprinting method, and TiO2 is selected as the oblique tooth grating structure material.

[0030] By adopting the above technical solution, the present invention has the following advantages:

[0031] Glancing Angle Deposition (GLAD), also known as grazing angle deposition or large incident angle deposition, is generally used to prepare thin films with controllable morphology (see the patent "Micron-scale Space Fragment Protection Film for Optical Glass" in CN106987804B) and nanowires (see the patent "Preparation Method of Indium Antimonide Nanowires and Manganese Doping Based on Multi-Step Grazing Angle Deposition" in CN105862122B).

[0032] This invention applies angled deposition (GLAD) technology to the fabrication of high-refractive-index slanted tooth gratings. It solves the technical problems of slanted tooth grating fabrication methods, such as those using Faraday cages for reactive ion etching and those using ion beam etching and reactive ion beam etching, which are difficult to apply to certain high-refractive-index materials. It also addresses the technical challenges of nanoparticle filling in nanoimprint grating fabrication methods, which require strict control, have limited template lifespan, and may introduce defects during pattern transfer. Furthermore, because this process directly uses the corresponding vapor deposition material for deposition rather than nanoparticle implantation, there is no concern about affecting the material's scattering efficiency.

[0033] The method proposed in this invention enables the fabrication of multiple repeating unit oblique tooth grating structures on a single wafer. Subsequently, multiple coupling units are separated through chip dicing. Integrating a single coupling unit onto a wafer with already fabricated coupling units achieves optical coupling. This method significantly improves the large-scale fabrication efficiency of this optical device. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the steps of a method for manufacturing a high-refractive-index oblique toothed grating according to Example 1.

[0035] Figure 2 This is a flowchart illustrating the steps of a method for manufacturing a high-refractive-index oblique toothed grating according to Example 2.

[0036] Figure 3 This is a flowchart illustrating the steps of a method for manufacturing a high-refractive-index oblique toothed grating according to Example 3.

[0037] In the picture:

[0038] 1-Quartz glass; 2-ZEP520A electron beam resist; 3-Electron beam; 4-TiO2 vapor deposition source; 5-Vapor deposition tilt angle; 6-Hedged grating tilt angle; 7-TiO2; 8-Polystyrene; 9-Thermal nanoimprint template; 10-HfO2 and SiO2; 11-HfO2 and SiO2 vapor deposition source; 12-PET substrate; 13-UV nanoimprint adhesive; 14-UV nanoimprint template; 15-UV. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Example 1

[0041] like Figure 1 As shown, this embodiment provides a method for manufacturing a high refractive index oblique tooth grating, which manufactures a TiO2 (n=2.3) oblique tooth grating.

[0042] The specific steps include:

[0043] 1. Quartz glass 1 is selected as the substrate;

[0044] Quartz glass 1 is mainly composed of SiO2;

[0045] 2. Spin-coat a layer of ZEP520A electron beam resist 2 onto the substrate surface;

[0046] ZEP520A electron beam resist 2 was diluted with anisole at a ratio of 1:1.

[0047] 3. Bake on a hot plate at 180°C for 3 minutes;

[0048] 4. For example Figure 1 As shown in a, exposure was performed using electron beam 3 with an exposure dose of 150 μC / cm. 2 The design pattern is formed by exposure using an electron beam 3;

[0049] Here, the ZEP520A electron beam resist 2 pattern has a width of 150 nm and a period of 400 nm;

[0050] 5. For example Figure 1 As shown in b, the sample was immersed in ZED-N50 developer at room temperature for 90 seconds, and then rinsed with isopropanol and dried.

[0051] 6. Under the following etching conditions, transfer the pattern in the resist to the SiO2 layer, where the SiO2 seed layer pattern height is 30 nm:

[0052] Reactive ion etching conditions: 15 sccm O2, 40 ccm C4F8, 10 mTorr, 200 W RF, 2500 W ICP, 50°C;

[0053] 7. For example Figure 1 As shown in c, oxygen plasma is used to remove residual ZEP520A resist;

[0054] 8. For example Figure 1 As shown in d, TiO27 was deposited above the seed layer using TiO2 evaporation source 4 via tilt angle deposition (GLAD) technology;

[0055] In this embodiment, the tilt angle deposition (GLAD) technique is achieved by electron beam evaporation of TiO2, wherein the evaporation tilt angle 5 is 85°, and the height of the TiO27 obtained by evaporation is determined by the evaporation rate and evaporation time.

[0056] This technical solution can yield a TiO2 oblique tooth grating structure with a period of 400 nm, an oblique tooth grating tilt angle of approximately 55°, and a duty cycle of approximately 0.375. Following this embodiment, mass production of high-refractive-index oblique tooth gratings can be achieved.

[0057] Example 2

[0058] like Figure 2 As shown, this embodiment provides a method for manufacturing a high refractive index oblique tooth grating, which manufactures an oblique tooth grating of a mixture of HfO2 and SiO2 (n=1.9).

[0059] The specific steps include:

[0060] 1. Quartz glass 1 is selected as the substrate;

[0061] 2. For example Figure 2 As shown in Figure a, a layer of polystyrene 8, approximately 200 nm thick, is spin-coated onto the substrate surface;

[0062] 3. For example Figure 2As shown in b, thermal nanoimprinting was performed using the prepared thermal nanoimprint template 9. The imprinting conditions were: temperature 150℃, pressure 10 bar, and time 3 min.

[0063] 4. Cool to 40℃ and demold to obtain the following result. Figure 2 The structure shown in c;

[0064] 5. For example Figure 2 As shown in d, oxygen plasma was used to remove residual polystyrene, resulting in a polystyrene pattern with a period of 200 nm and a width of 50 nm.

[0065] 6. For example Figure 2 As shown in e, under the following etching conditions, the pattern in the resist is transferred to the SiO2 layer, the SiO2 seed layer pattern height is 30 nm, and the remaining polystyrene mask is removed:

[0066] Reactive ion etching conditions: 15 sccm O2, 40 ccm C4F8, 10 mTorr, 200 W RF, 2500 W ICP, 50°C;

[0067] 7. For example Figure 2 As shown in f, HfO2 and SiO210 are deposited above the seed layer using the tilted angle deposition technique (GLAD) through HfO2 and SiO2 evaporation source 11;

[0068] In this embodiment, the tilt angle deposition (GLAD) technique is achieved by synchronous electron beam evaporation of HfO2 and SiO2, wherein the evaporation tilt angle is 80°, the height of HfO2 and SiO2 obtained by evaporation is determined by the evaporation rate and evaporation time, and the proportion is controlled by their respective evaporation rates, wherein the proportion of SiO2 is 14%.

[0069] This technical solution can yield HfO2 and SiO2 oblique tooth grating structures with a period of 200 nm, an oblique tooth grating tilt angle of 50°, and a duty cycle of approximately 0.25. Following this embodiment, mass production of high-refractive-index oblique tooth gratings can be achieved.

[0070] Example 3

[0071] like Figure 3 As shown, this embodiment provides a method for manufacturing a high refractive index oblique tooth grating, which manufactures a TiO2 (n=2.3) oblique tooth grating.

[0072] The specific steps include:

[0073] 1. PET (polyethylene terephthalate) is selected as the substrate;

[0074] 2. For example Figure 3As shown in a, a layer of ultraviolet nanoimprint adhesive 13 (PL-R-PC1000) with a thickness of about 200 nm is spin-coated on the surface of PET substrate 12;

[0075] 3. For example Figure 3 As shown in b, UV nanoimprinting was performed using the prepared UV nanoimprint template 14 via UV15. The imprinting conditions were: light intensity 70mW / cm2, pressure 400kPa, and time 3min.

[0076] 4. For example Figure 3 As shown in d, the mold is removed and the residue is removed using oxygen-fluorine plasma to obtain the seed layer pattern;

[0077] UV nanoimprint 13 (PL-R-PC1000) contains silicon, and some fluorine-containing gas, such as CF4, needs to be added to the oxygen during etching;

[0078] The seed pattern here is 100nm wide, has a period of 200nm, and a seed layer height of 20nm;

[0079] 5. For example Figure 3 As shown in e, TiO27 is deposited above the seed layer using TiO2 evaporation source 4 via tilt angle deposition (GLAD) technology;

[0080] In this embodiment, the tilt angle deposition (GLAD) technique is achieved by electron beam evaporation of TiO2, wherein the evaporation tilt angle 5 is 83°, and the height of the TiO27 obtained by evaporation is determined by the evaporation rate and evaporation time.

[0081] This technical solution can yield a TiO2 oblique tooth grating structure with a period of 200 nm, an oblique tooth grating tilt angle of approximately 52°, and a duty cycle of approximately 0.5. Following this embodiment, mass production of high-refractive-index oblique tooth gratings can be achieved.

[0082] If the final grating structure has some defects, they can be repaired through subsequent processing methods such as annealing.

[0083] This invention presents a novel method for fabricating high-refractive-index oblique-tooth gratings, combining electron beam lithography, tilt angle deposition, and etching. While applicable to experimental research and development, electron beam exposure has relatively low efficiency; therefore, advanced lithography techniques are generally used to replace electron beam exposure for mass production. Subsequent mass production can be achieved by combining nanoimprint lithography.

[0084] The method proposed in this invention enables the fabrication of multiple repeating unit oblique tooth grating structures on a single wafer. Subsequently, multiple coupling units are separated through chip dicing. Integrating a single coupling unit onto a wafer with already fabricated coupling units achieves optical coupling. This method significantly improves the large-scale fabrication efficiency of this optical device.

[0085] In addition to the preferred embodiments described above, there are other embodiments of the present invention. Those skilled in the art can make various changes and modifications based on the present invention, and all such changes and modifications should fall within the scope defined by the appended claims, as long as they do not depart from the spirit of the present invention.

Claims

1. A method for manufacturing a high-refractive-index oblique toothed grating, characterized in that, Includes the following steps: S1, A seed layer pattern is formed on the grating substrate. The seed layer pattern consists of several lines arranged at periodic intervals. S2, deposit a layer of oblique tooth grating structure material on the seed layer pattern using grazing angle deposition technology to form the oblique tooth structure of the grating; The helical tooth structure is composed entirely of a high refractive index material.

2. The method for manufacturing a high refractive index oblique toothed grating according to claim 1, characterized in that, Step S1 specifically includes: a101, spin-coating an electron beam resist onto the grating substrate; a102, using electron beam exposure to form a design pattern on an electron beam resist layer; a103, after exposure, is developed at room temperature; a104 uses reactive ion etching to transfer the design pattern on the electron beam resist layer to the grating substrate, forming a seed layer pattern; a105 utilizes plasma to remove residual electron beam resist.

3. The method for manufacturing a high refractive index oblique toothed grating according to claim 1, characterized in that, Step S1 specifically includes: b101, spin-coating a layer of imprinting material onto the grating substrate; b102, using an imprinting template to perform nanoimprinting on the imprinting material to form several periodically spaced lines; b103, using plasma to remove the embossing material until the embossing material between the lines is removed, thus obtaining the embossed pattern; b104 uses reactive ion etching to transfer the design pattern on the imprinted pattern to the grating substrate to form a seed layer pattern; b105 uses plasma to remove residual imprint material.

4. The method for manufacturing a high refractive index oblique toothed grating according to claim 1, characterized in that, Step S1 specifically includes: c101, spin-coating a layer of imprinting material onto the grating substrate; c102, using an imprinting template to perform nanoimprinting on the imprinting material to form lines with several periodic intervals; c103 uses plasma to remove the imprinting material until the imprinting material between the lines is removed, thus obtaining a seed layer pattern.

5. The method for manufacturing a high refractive index oblique toothed grating according to claim 2, characterized in that, Quartz glass was selected as the grating substrate, ZEP520A diluted 1:1 with anisole was selected as the electron beam resist, and TiO2 was selected as the material for the oblique tooth grating structure.

6. The method for manufacturing a high refractive index oblique toothed grating according to claim 3, characterized in that, Quartz glass was selected as the grating substrate, polystyrene was selected as the imprinting material, the nanoimprinting method was thermal nanoimprinting, and HfO2 and SiO2 were selected as the oblique tooth grating structure materials.

7. The method for manufacturing a high refractive index oblique toothed grating according to claim 4, characterized in that, Polyethylene terephthalate was selected as the grating substrate, the imprinting material was ultraviolet nanoimprint adhesive, the nanoimprinting method was ultraviolet nanoimprinting, and TiO2 was selected as the oblique tooth grating structure material.

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