Method for forming binary grating structure through one-time etching

Abstract

The invention provides a method for forming a binary grating structure through one-time etching, and the method comprises the steps: providing a substrate which comprises a first grating region and a second grating region which are sequentially arranged; forming a grating film layer on the surface of the substrate, wherein the thickness of the grating film layer on the first grating area is greater than that of the grating film layer on the second grating area; forming a mask layer on the surface of the grating film layer and patterning the mask layer, wherein the morphology of the mask layer on the first grating area is different from the morphology of the mask layer on the second grating area; the patterned mask layer serves as a mask, the grating film layer is etched at a time, a first grating structure is formed on the first grating area, a second grating structure is formed on the second grating area, a binary grating structure is formed, and the morphology of the first grating structure is different from that of the second grating structure. One-time etching of the binary grating is achieved, various grating structures are formed through one-time etching, and the production efficiency and the performance of optical waveguide products are improved.

Description

[0001] This is a divisional application. The original application number is 2024103817893, and the application date is March 29, 2024. Technical Field

[0002] This invention relates to the field of semiconductor devices, and more particularly to a method for forming a binary grating structure in a single etching process. Background Technology

[0003] Compared to unary gratings, optical waveguides based on binary gratings are more efficient. Therefore, developing single-pass imprinting and etching binary gratings without increasing process complexity is of great significance, as it not only directly improves the overall performance of the product but also indirectly reduces the product cost.

[0004] In traditional fabrication processes, single imprint etching can only produce a single unidimensional straight-tooth structure, not a binary structure. To produce a binary structure, multiple imprint etching processes are usually required. However, multiple imprint etching processes are inefficient, costly, and difficult to guarantee the stability and consistency of the fabricated structure and the performance of the grating structure product. Furthermore, they are not conducive to large-scale mass production.

[0005] Therefore, how to prepare binary grating structures through a single imprint etching process has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] This invention provides a method for forming a binary grating structure through a single etching process, thereby solving the problem of how to form a binary grating structure through a single etching process.

[0007] According to a first aspect of the present invention, a method for forming a binary grating structure in a single etching step is provided, comprising:

[0008] A substrate is provided, the substrate comprising: a first grating region and a second grating region disposed sequentially;

[0009] A grating film layer is formed on the surface of the substrate, and the thickness of the grating film layer on the first grating region is greater than the thickness of the grating film layer on the second grating region;

[0010] A mask layer is formed on the surface of the grating film layer and the mask layer is patterned. The morphology of the mask layer located in the first grating region is different from the morphology of the mask layer located in the second grating region.

[0011] Using the patterned mask layer as a mask, the grating film layer is etched once to form a first grating structure on the first grating region and a second grating structure on the second grating region, thus forming the binary grating structure, wherein the morphology of the first grating structure is different from that of the second grating structure.

[0012] Optionally, the mask layer located in the first grating region is flush with the surface of the mask layer located on the first grating region.

[0013] Optionally, the difference between the thickness of the grating film layer formed on the first grating region and the surface thickness of the grating film layer formed on the second grating region is a first difference value.

[0014] △H=(h1-h2)*S;

[0015] Where h1 is the height of the first grating structure; h2 is the height of the second grating structure; S is the etching selection ratio of the patterned mask layer and the grating film layer; ΔH is the first difference value;

[0016] S=V 掩膜层 / V 光栅膜层 ;

[0017] Among them, V 掩膜层 The etching rate of the patterned mask layer; V 光栅膜层 It is the etching rate of the grating film.

[0018] Optionally, the etching time for etching the grating film layer once is the first etching time; the first etching time

[0019] T=h2 / V 光栅膜层 +△H / V 掩膜层 ;

[0020] Where T is the first etching time.

[0021] Optionally, the height h1 of the first grating structure and the thickness H1 of the mask layer on the first grating region, and the height h2 of the second grating structure and the thickness H2 of the mask layer on the second grating region, respectively satisfy the following relationships:

[0022] The thickness H1 of the mask layer on the first grating region:

[0023] H1 = h1 * S;

[0024] The thickness H2 of the mask layer on the second grating region:

[0025] H2>h2*S.

[0026] Optionally, a mask layer is formed and patterned on the surface of the grating film layer, specifically: a first patterned mask layer is formed on the surface of the grating film layer in the first grating region, and a second patterned mask layer is formed on the surface of the grating film layer in the second grating region; and further defined as follows:

[0027] A mask material layer is formed on the surface of the grating film layer, and the surface of the mask material layer in the first grating region is flush with the surface of the mask material layer in the second grating region.

[0028] The mask material layer is patterned to form the first patterned mask layer on the surface of the grating film layer in the first grating region, and the second patterned mask layer on the surface of the grating film layer in the second grating region.

[0029] Optionally, the mask material layer is an imprinting adhesive layer, and the mask material layer is patterned, including:

[0030] The printing adhesive layer is printed using an impression master, so that a first patterned printing adhesive layer and a second patterned printing adhesive layer are formed on the surfaces of the grating film layer on the first grating region and the grating film layer on the second grating region, respectively; the first patterned printing adhesive layer and the second patterned printing adhesive layer are adapted to the regions corresponding to the impression master, and the first patterned printing adhesive layer and the second patterned printing adhesive layer have different heights.

[0031] Optionally, a method for forming a grating film layer on the surface of the substrate includes:

[0032] A first grating film is formed on the surface of the substrate;

[0033] A first patterned photoresist layer is formed on the surface of the first grating film in the second grating region;

[0034] A second grating film of a first thickness is deposited on the surface of the first patterned photoresist layer and on the surface of the first grating film in the first grating region.

[0035] Remove the first patterned photoresist layer.

[0036] Optionally, a method for forming a grating film layer on the surface of the substrate includes:

[0037] A first grating film is formed on the surface of the substrate;

[0038] A second patterned photoresist layer is formed on the surface of the first grating film in the first grating region;

[0039] Using the second patterned photoresist layer as a mask, the first grating film with a first thickness located in the second grating region is etched away;

[0040] Remove the second patterned photoresist layer.

[0041] Optionally, the substrate further includes a third grating region; when forming a first grating structure on the first grating region and a second grating structure on the second grating region, the method further includes:

[0042] A third grating structure is formed in the third grating region, and the height of the third grating structure is different from the height of the second grating structure.

[0043] Optionally, the difference between the thickness of the grating film layer formed on the first grating region and the surface thickness of the grating film layer formed on the second grating region or the third grating region is a first difference value.

[0044] △H=(h1-max(h2,h3))*S;

[0045] Where h1 is the height of the first grating structure; h2 is the height of the second grating structure; S is the etching selectivity ratio of the patterned mask layer to the grating film layer; h3 is the height of the third grating structure; and ΔH is the first difference.

[0046] Optionally, the etching time for one etching of the grating film is the first etching time; the first etching time T = max(h2, h3) / V 光栅膜层 +△H / V 掩膜层 Where T is the first etching time.

[0047] Optionally, when a height gradient of the second grating structure is formed on the second grating region, h2 is the maximum height value of the height gradient of the second grating structure.

[0048] Optionally, when a height gradient is formed on the second grating region and / or on the third grating region, h2 is the maximum height value of the height gradient of the second grating structure, and h3 is the maximum height value of the height gradient of the third grating structure.

[0049] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0050] The technical solution provided by this invention involves creating a grating film layer in a first grating region of a substrate with a surface height greater than that in a second grating region. A mask layer is coated on the surface of the grating film layer. Based on the pre-defined morphologies of the first and second grating structures, the first grating region and the mask layer on it are patterned. Finally, using the patterned mask layer as a mask, the grating film layer is etched in a single process to form first and second grating structures with different morphologies in the first and second grating regions, respectively. This single etching process forms the binary grating structure. As can be seen, the technical solution provided by this invention cleverly designs the thickness of the grating film layer in different grating regions, resulting in varying thicknesses in each region. This achieves the goal of forming a binary grating structure in a single etching process, directly improving overall product performance and production efficiency, reducing production costs, and minimizing the multi-step processes and alignment issues inherent in existing technologies. This results in better structural stability and consistency, and is more conducive to improving diffraction efficiency.

[0051] Furthermore, the present invention also provides a method for determining the first difference in height between grating film layers in different grating regions by using the height of the first grating structure, the height of the second grating structure, and the etching selectivity ratio of the patterned mask layer and the grating film layer, thereby ensuring the purpose of forming a binary grating structure in a single etching operation.

[0052] Furthermore, a method is provided to determine the first etching time for forming a binary grating structure by means of the etching rate of the patterned mask layer, the etching rate of the grating film layer, the height of the second grating structure, and the first difference. By using the determined unified first etching time in different grating structure regions, precise control of the height and morphology of the grating units in the first and second grating structures is achieved, resulting in unexpected technical effects. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 This is a flowchart illustrating a method for forming a binary grating structure through a single etching step according to an embodiment of the present invention.

[0055] Figures 2-12 This is a schematic diagram of the device structure at different process stages fabricated according to a method for forming a binary grating structure by a single etching step, provided in an embodiment of the present invention.

[0056] Figures 13-16 This is a schematic diagram of the device structure at different process stages fabricated according to a method for forming a binary grating structure by a single etching step, provided in another embodiment of the present invention.

[0057] Figures 17-19 These are schematic diagrams of device structures at different process stages fabricated according to a method for forming a binary grating structure by a single etching step, provided in other embodiments of the present invention.

[0058] Explanation of reference numerals in the attached figures:

[0059] 101, 201 substrates;

[0060] 1011 - First grating region;

[0061] 1012 - Second grating region;

[0062] 1013 - Third grating region;

[0063] 102, 202 - grating film layers;

[0064] 1021, 2021 - First grating film;

[0065] 1022 - Second grating film;

[0066] 103 - First photoresist layer;

[0067] 203 - Second photoresist layer;

[0068] 2031 - Second patterned photoresist layer;

[0069] 1031 - First patterned photoresist layer;

[0070] 104 - Mask material layer;

[0071] 1041 - First patterned mask layer;

[0072] 1042 - Second patterned mask layer;

[0073] 1043 - Third patterned mask layer;

[0074] 105 - First grating structure;

[0075] 106 - Second grating structure;

[0076] 107 - Third grating structure. Detailed Implementation

[0077] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0078] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. The terms "above" and "over," and any variations thereof, are intended to describe positional relationships and do not imply direct contact between the described objects.

[0079] As described in the background art, since the optical waveguide of binary gratings is more efficient, and the height of the blazed grating, trapezoidal irregular grating or oblique tooth grating that needs to be fabricated is usually greater than the height of the straight tooth grating, the existing binary structure fabrication process can only be achieved by two imprint etching steps because the former needs to be protected and fabricated intact.

[0080] However, due to the complexity of the process and alignment issues involved in two imprinting or etching processes, the process of fabricating binary grating structures using two imprinting and etching methods is inefficient, costly, and makes it difficult to guarantee the stability and consistency of the fabricated structure.

[0081] In view of this, the inventors of this application propose a method for forming a binary grating structure by etching in one step. This method involves fabricating grating films of different heights on a substrate, forming patterned mask layers with different morphologies on the grating films of different heights, and using the patterned mask layers as masks to etch the grating films in one step. This results in the formation of blazed gratings, trapezoidal irregular gratings, or oblique tooth gratings in the regions where the grating films are formed at higher heights, and straight tooth gratings in the regions where the grating films are formed at relatively lower heights. This method achieves the fabrication of a binary grating structure through a single etching step, improving the performance of the binary grating structure, saving fabrication steps, and increasing manufacturing efficiency and mass production capabilities.

[0082] The binary grating structure defined in this application refers to a grating region comprising at least two different grating structures, namely a first grating structure, a second grating structure, or a first grating structure, a second grating structure, and a third grating structure, etc. It can be further limited to various forms, such as a binary grating structure of a blazed grating and a straight-tooth grating, or a binary grating structure of a trapezoidal irregular grating and a straight-tooth grating, etc. This invention does not further limit these forms.

[0083] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0084] Figure 1 This is a schematic diagram of the process for forming a binary grating structure through a single etching step according to an embodiment of the present invention, including:

[0085] Step S11, providing a substrate, the substrate comprising: a first grating region and a second grating region arranged sequentially;

[0086] Step S12: A grating film layer is formed on the surface of the substrate, and the thickness of the grating film layer on the first grating region is greater than the thickness of the grating film layer on the second grating region.

[0087] Step S13: A mask layer is formed on the surface of the grating film layer and the mask layer is patterned. The morphology of the mask layer located in the first grating region is different from the morphology of the mask layer located in the second grating region.

[0088] Step S14: Using the patterned mask layer as a mask, the grating film layer is etched once to form a first grating structure on the first grating region and a second grating structure on the second grating region, thus forming the binary grating structure, wherein the morphology of the first grating structure is different from that of the second grating structure.

[0089] The technical solution provided by this invention involves coating a mask layer on the surface of the grating film layer in the first grating region of the substrate with a surface thickness greater than that in the second grating region. Based on the pre-defined morphologies of the first and second grating structures, the first grating region and the mask layer on it are patterned. Finally, using the patterned mask layer as a mask, the grating film layer is etched in a single step to form first and second grating structures with different morphologies in the first and second grating regions, respectively. Therefore, the technical solution provided by this invention, by cleverly designing the thickness of the grating film layer in different grating regions and limiting the thickness of the grating film layer in the first grating region to be greater than that in the second grating region, achieves the goal of forming a binary grating structure in a single etching step, improving overall product performance and production efficiency, and reducing product production costs.

[0090] The following will describe in detail an embodiment of the process of forming a binary grating structure by etching in a single step, with reference to the accompanying drawings.

[0091] Figures 2 to 12 This is a cross-sectional schematic diagram of a process for forming a binary grating structure by etching in a single step, according to an embodiment of the present invention.

[0092] Please refer to Figure 2 A substrate 101 is provided, the substrate 101 including a first grating region 1011 and a second grating region 1012 arranged sequentially.

[0093] The first grating region 1011 and the second grating region 1012 are used to form the grating film layer 102.

[0094] In one embodiment, the first grating region 1011 and the second grating region 1012 are separated by a first design distance.

[0095] In one specific embodiment, when the binary grating structure refers to the binary grating structure in the diffractive waveguide, the first grating region 1011 refers to the coupling region, which is used to form the coupling structure; the second grating region 1012 refers to the coupling grating, which is used to form the coupling structure; and the first design distance is determined according to the distance requirement between the coupling region and the coupling region.

[0096] The sequential arrangement here refers to the arrangement of the first grating region 1011 and the second grating region 1012 on the substrate 101 in a certain manner. For example, when a binary grating structure is used to form a diffractive waveguide, the sequential arrangement specifically refers to the arrangement of the coupling-in region and the coupling-out region on the waveguide.

[0097] Subsequently, a grating film layer 102 is formed on the surface of the substrate 101, and the thickness of the grating film layer 102 on the first grating region 1011 is greater than the thickness of the grating film layer 102 on the second grating region 1012. The formation process of the grating film layer is as follows: Figures 3 to 7 As shown.

[0098] Please refer to Figure 3 A first grating film 1021 is formed on the surface of the substrate 101.

[0099] The first grating material is a high-refractive-index material. Specifically, it can be lithium niobate, titanium dioxide, gallium nitride, silicon carbide, zinc sulfide, etc.

[0100] The process used to form the first grating film 1021 can be: grating film deposition process including but not limited to diamond cutting tool extrusion polishing, metal dielectric multilayer film preparation, multilayer film deposition technology, inductively coupled plasma chemical vapor deposition, electron gun thermal evaporation, and low-energy ion bombardment, etc.

[0101] Depending on the actual process requirements, the thickness of the first grating film layer 1021 can be: greater than or equal to 15 nanometers, greater than or equal to 45 nanometers, greater than or equal to 50 nanometers, greater than or equal to 80 nanometers, or greater than or equal to 100 nanometers, etc. Please refer to... Figure 4 A first photoresist layer 103 is formed on the surface of the first grating film 1021.

[0102] The first photoresist layer 103 is made of materials including polymethyl methacrylate (PMMA), polymethyl glutarimide, phenolic resin, and polyamide, and its composition also includes photosensitive resin, sensitizer, and solvent.

[0103] When coating the first photoresist layer 103, the following methods are used: the main methods of photoresist coating include ultrasonic spraying, spin coating, dip coating, etc.

[0104] Please refer to Figure 5 The first photoresist layer 103 is exposed and developed to form the first patterned photoresist layer 1031 on the surface of the first grating film 1021 in the second grating region 1012.

[0105] Please refer to Figure 6 A second grating film 1022 with a first thickness ΔH is deposited on the surface of the first patterned photoresist layer 1031 and the surface of the first grating film 1021 of the first grating region 1011.

[0106] In one embodiment, the coating method for the grating material includes, but is not limited to, evaporation deposition, plasma sputtering, ion beam sputtering, and improved processes such as fiber sample rotation and electroless nickel plating.

[0107] Please refer to Figure 7 Remove the first patterned photoresist layer 1031, and at the same time remove the second grating film 1022 on its surface to form a grating film layer 102.

[0108] In other regions between the first grating region 1011 and the second grating region 1012, the thickness of the mask can be the same as the thickness of the mask on the first grating region 1011 or the thickness of the mask on the second grating region 1012.

[0109] The statement that the thickness of the grating film layer 102 on the first grating region 1011 is greater than the thickness of the grating film layer 102 on the second grating region 1012 means that the thickness of the grating film layer 102 on the first grating region 1011 and the thickness of the grating film layer 102 on the second grating region 1012 change discontinuously, i.e., there is a step-like thickness difference, such as ΔH, and the thickness of the grating film layer 102 on the first grating region 1011 is greater than the thickness of the grating film layer 102 on the second grating region 1012.

[0110] In one embodiment of the present invention, the surface of the grating film layer 102 located in the first grating region 1011 is flush with the surface of the grating film layer 102 located in the second grating region 1012, and the thickness of the grating film layer 102 in the first grating region 1011 is greater than the thickness of the grating film layer 102 in the second grating region 1012.

[0111] The discontinuous change here can be specifically understood as follows: the surface height of the grating film layer 102 located in the first grating region 1011 is the same; for example: in the first grating region 1011, the thickness of the grating film layer 102 is the same with no thickness change, and in the second grating region 1012, the thickness of the grating film layer 102 is the same with no thickness change; or for example: in the first grating region 1011, the thickness of the grating film layer 102 is the same with no thickness change, and in the second grating region 1012, the thickness of the grating film layer 102 changes continuously or intermittently; the continuous thickness change refers to: the surface height of the grating film layer 102 in the second grating region 1012 changes continuously, forming a wavy or curved surface; the staged change refers to: the second grating region 1012 is divided into several second grating sub-regions, the surface height of the grating film layer 102 in each region is the same, and the surface height of the grating film layer 102 in at least two second grating sub-regions is different.

[0112] By controlling the first difference, i.e. the thickness difference, between the surface height of the grating film layer 102 formed on the first grating region 1011 and the surface height of the grating film layer 102 formed on the second grating region 1012, it can be ensured that when the patterned mask layer is used as a mask and the grating film layer is etched once, after a certain etching time, the morphology of the mask layer on the second grating region 1012 can be transferred to the grating film layer 102 at the same time as the first grating structure is etched, so as to form a second grating structure with grating units of a certain height.

[0113] For example, when a blazed grating structure is formed on the first grating region 1011 and a straight-tooth grating is formed on the second grating structure 1012, by taking advantage of the surface thickness difference of the grating film layer 102 on the first grating region 1011 and the second grating region 1012, when the complete blazed grating structure is etched and reshaped, after a certain etching time, the blazed structure is just etched and reshaped, and the straight-tooth grating is just etched and reshaped, thereby forming the binary blazed grating structure and the straight-tooth grating structure in one etching.

[0114] To achieve the goal of forming a binary grating structure in a single etching operation, the first difference is determined by the etching method used, the etching selection ratio of the grating film material and the mask layer material, the height of the grating unit in the preset first grating structure, and the height of the grating unit in the second grating structure. Specifically, the present invention provides the following embodiment.

[0115] The first difference ΔH = (h1 - h2) * S;

[0116] h1 is the height of the first grating structure; h2 is the height of the second grating structure; S is the etching selection ratio of the patterned mask layer and the grating film layer; ΔH is the first difference value;

[0117] In the above formula, S=V 掩膜层 / V 光栅膜层102 ;

[0118] Among them, V 掩膜层 The etching rate of the patterned mask layer; V 光栅膜层102 It is the etching rate of the grating film layer 102.

[0119] In some embodiments, when a height gradient of the second grating structure is formed on the second grating region, h2 is the maximum height value of the height gradient of the second grating structure. For example, if the second grating structure in the second grating region includes grating structures of multiple different depths, i.e., a height-gradient grating structure is formed, then when calculating the first difference ΔH, h2 refers to the maximum grating height value of the height gradient of the second grating structure. When the depth of the second grating structure remains constant, h2 is the height of the second grating structure. A mask layer is formed on the surface of the grating film layer 102 and the mask layer is patterned. The morphology of the mask layer located on the first grating region 1011 is different from the morphology of the mask layer located on the second grating region 1012.

[0120] In one embodiment, a first patterned mask layer is formed on the surface of the grating film layer 102 on the first grating region 1011, and a second patterned mask layer is formed on the surface of the grating film layer 102 on the second grating region 1012. The formation process of the first and second patterned mask layers is as follows: Figures 8 to 10 As shown.

[0121] Please refer to Figure 8 A mask material layer 104 is formed on the surface of the grating film layer 102, and the mask material layer 104 located in the first grating region 1011 is flush with the surface of the mask material layer 104 located in the second grating region 1012.

[0122] The mask material layer 104 can be made of inorganic thin film materials such as TiN (titanium nitride), SiN (silicon nitride), and SiO2 (silicon dioxide).

[0123] Chemical vapor deposition (CVD) or spin coating (SOC) can be used to form the mask material layer.

[0124] In one embodiment, the mask material layer 104 is an imprinting adhesive layer.

[0125] In one embodiment, the imprinting adhesive layer is a nanoimprinting adhesive layer. Nanoimprinting adhesives can be divided into two main categories: thermosetting and UV-curing. Thermosetting imprinting adhesives require high temperature and high pressure to complete the pattern replication process, while UV-curing imprinting adhesives are cured by ultraviolet light irradiation and do not require high temperature and high pressure. This makes UV-curing imprinting adhesives exhibit better alignment performance in multilayer structure imprinting.

[0126] Specifically, the nanoimprint adhesive layer can be composed of polyvinylphenol and polymethyl methacrylate. Please refer to [reference needed]. Figure 9 The mask material layer 104 is patterned to form the first patterned mask layer 1041 on the surface of the grating film layer 102 on the first grating region 1011, and the second patterned mask layer 1042 on the surface of the grating film layer 102 on the second grating region 1012.

[0127] In one embodiment, a first patterned mask layer 1041 is used to fabricate a first grating structure with a blazed irregular shape; a second patterned mask layer 1042 is used to fabricate a second grating structure with straight teeth. To ensure a single etching process, the first grating structure and the second grating structure can be formed simultaneously on the substrate 101 of the first grating region 1011 and the second grating region 1012, and the first grating structure and the second grating structure formed on the substrate 101 conform to a preset height. In a further technical solution of the present invention, the surface height of the mask layer in different regions is specified when etching the grating structure, and the following embodiment is provided.

[0128] In one embodiment, the height h1 of the first grating structure and the thickness H1 of the mask layer on the first grating region 1011, and the height h2 of the second grating structure and the thickness H2 of the mask layer on the second grating region 1012, respectively satisfy the following relationships:

[0129] The thickness of the mask layer on the first grating region 1011 is H1 = h1 * S; the thickness of the mask layer on the second grating region 1012 is H2 > h2 * S.

[0130] By controlling the thickness H2>h2*S of the mask layer on the second grating region 1012, on the one hand, it prioritizes ensuring that the grating structure of the first grating region is etched while also taking into account the grating structure of the second grating region. Due to the characteristics of the grating structure in the first grating region, logically speaking, the etching time of the mask layer forming this structure is longer than that of the second grating region. Therefore, in this application, in order to ensure that the binary grating structure is formed in one etching, the thickness of the mask layer in the second grating region is increased under the same etching time, which makes it easier to take into account both grating structures and makes the grating structure in the second grating region easier to form or reproduce. On the other hand, it also ensures that the substrate 101 is not damaged by etching.

[0131] In one embodiment, when the mask material layer 104 is an imprinting adhesive layer, the mask material layer 104 is patterned, including:

[0132] Step S1321: Imprint the imprinting adhesive layer using an imprinting master, so as to form a first patterned imprinting adhesive layer and a second patterned imprinting adhesive layer on the surfaces of the grating film layer 102 on the first grating region 1011 and the grating film layer 102 on the second grating region 1012, respectively; the first patterned imprinting adhesive layer and the second patterned imprinting adhesive layer are adapted to the regions corresponding to the imprinting master, and the first patterned imprinting adhesive layer and the second patterned imprinting adhesive layer have different heights.

[0133] In one embodiment, a nanoimprinting process is used when imprinting the imprinting adhesive layer using an imprinting master. In other embodiments, other processing methods can be used to pattern the mask material layer 104, which will not be elaborated here.

[0134] Nanoimprinting has the following advantages: the nanoimprinting process is stable and has good mass production capabilities; compared with other patterning methods, nanoimprinting is more efficient, has better mass production capabilities, and lower costs.

[0135] In another embodiment, please refer to Figure 10 The first patterned mask layer 1041 is used to fabricate a trapezoidal irregular structure first grating structure; the second patterned mask layer 1042 is used to fabricate a straight-toothed second grating structure. Figure 9 Please continue to refer to the above. Figure 11Using the patterned mask layer as a mask, the grating film layer 102 is etched once to form a first grating structure 105 on the first grating region 1011 and a second grating structure 106 on the second grating region 1012, thus forming the binary grating structure. The morphology of the first grating structure 105 is different from that of the second grating structure 106.

[0136] When etching the grating film 102 once, the etching process used is a dry etching process, which is usually carried out by reactive ion etching.

[0137] In one embodiment, since the morphology of the mask layer on the first grating region 1011 is different from that on the second grating region 1012 in the aforementioned steps, the morphology of the first grating structure 105 is also different from that of the second grating structure 106 in this step, and matches the morphology of the mask layer. Specifically, when the morphology of the mask layer on the first grating region 1011 is a blazed irregular tooth shape and the morphology of the mask layer on the second grating region 1012 is a straight tooth shape, after one etching to form a binary grating structure, specifically, the morphology of the first grating structure 105 formed on the first grating region 1011 is a blazed irregular tooth shape and the morphology of the second grating structure 106 on the second grating region 1012 is a straight tooth shape.

[0138] Similarly, since there is also a design distance between the first grating region 1011 and the second grating region 1012, the same design distance is also formed between the first grating structure 105 and the second grating structure 106. In one embodiment, when the binary grating structure is applied in an optical waveguide, the design distance refers to the distance between the coupling-in grating and the coupling-out grating; within this design distance, the light beam propagates in the optical waveguide substrate.

[0139] This invention achieves the fabrication of a binary grating structure in a single etching process by setting grating film layers 102 of different heights in different grating regions, which greatly improves the efficiency and stability of binary grating structure products.

[0140] Furthermore, the present invention also provides an embodiment in which the etching time for etching the grating film layer 102 in one step is a first etching time; the first etching time

[0141] T=h2 / V 光栅膜层102 +△H / V 掩膜层 ;

[0142] Where T is the first etching time.

[0143] As can be seen, in this embodiment, the technical solution of the present invention predicts the etching cutoff time in step S14 in advance, provides the etching cutoff time for forming a binary grating structure in one etching, and at the same time realizes the precise control of the height of the grating unit in the first grating structure 105 and the second grating structure 106.

[0144] For example, when a blazed grating structure is formed on the first grating region 1011 and a straight-tooth grating is formed on the second grating structure 1012, by taking advantage of the surface thickness difference of the grating film layer 102 on the first grating region 1011 and the second grating region 1012, when the complete blazed grating structure is etched and reshaped, after a preset first etching time, the blazed structure is just etched and reshaped, and the straight-tooth grating is just etched and reshaped, thereby forming the binary blazed grating structure and the straight-tooth grating structure in one etching.

[0145] Furthermore, when fabricating a binary grating structure using nanoimprinting and nanoetching processes, after performing the subsequent step S14, the product based on this fabrication process—nanoimprinting patterning → etching → forming a binary grating structure—has the following advantages:

[0146] 1. The nanoimprinting process is stable and has good mass production capabilities;

[0147] 2. The nano-etching process is stable and has good mass production capabilities.

[0148] 3. Compared with other patterning methods, nanoimprinting is more efficient, has better mass production capabilities, and lower cost;

[0149] 4. The etching equipment is mature and stable, highly efficient, and relatively low in cost;

[0150] 5. Excellent performance of imprinted etched products: Since the efficiency of binary grating structure products is directly related to the refractive index of the grating film 102 and the substrate 101, nanoimprint etching uses inorganic materials with higher refractive index (TiO2, Nb2O5, SiC, etc.) to make gratings; the products have higher efficiency and better stability.

[0151] As can be seen, the technical solution provided by this invention enables the fabrication of binary grating structures through a single imprint etching process, combining the advantages of both single-stage etching and nanoimprinting. The resulting binary grating structure products exhibit higher efficiency and better stability.

[0152] In another embodiment, Figure 10 Please continue to refer to the above. Figure 12The patterned mask layer is a mask. The grating film layer 102 is etched once to form a first grating structure 105 on the first grating region 1011 and a second grating structure 106 on the second grating region 1012, thus forming the binary grating structure. The morphology of the first grating structure 105 is different from that of the second grating structure 106.

[0153] When the morphology of the mask layer on the first grating region 1011 is trapezoidal irregular tooth shape and the morphology of the mask layer on the second grating region 1012 is straight tooth shape, after one etching to form a binary grating structure, specifically, the morphology of the first grating structure 105 formed on the first grating region 1011 is trapezoidal irregular tooth shape and the morphology of the second grating structure 106 on the second grating region 1012 is straight tooth shape.

[0154] In summary, in one embodiment of the present invention, grating film layers of different heights are set in different grating regions by photolithography, and the binary grating structure is fabricated in a single etching process, which greatly improves the efficiency and stability of the binary grating structure product.

[0155] Simultaneously, a method for determining the first difference between the height of the mask layer in the first grating region and the height of the grating film layer in the second grating region is provided, ensuring the formation of a binary grating structure in a single etching operation. A method for determining the etching cutoff time for forming the binary grating structure in a single etching operation is also provided, achieving precise control over the height and morphology of the grating units in both the first and second grating structures. This embodiment also provides a nanoimprint etching scheme, integrating the advantages of single etching and nanoimprinting, further improving the efficiency and stability of the binary grating structure product.

[0156] Figures 13 to 16 This is a cross-sectional schematic diagram of another process for forming a binary grating structure through a single etching step according to an embodiment of the present invention. This embodiment is similar to... Figures 2 to 12 The difference between the embodiments lies in the method used to form the grating film layer on the surface of the substrate. In this embodiment, the method for forming the grating film layer on the surface of the substrate includes:

[0157] exist Figure 2 Please refer to the following: Figure 13 A first grating film 2021 is formed on the surface of the substrate 201. Please refer to... Figure 14 A second photoresist layer 203 is formed on the surface of the first grating film layer 202.

[0158] Please refer to Figure 15The second photoresist layer 203 is exposed and developed to form the second patterned photoresist layer 2031 on the surface of the first grating film in the first grating region. Please refer to... Figure 16 Using the second patterned photoresist layer 2031 as a mask, the first grating film with a first thickness ΔH located in the second grating region is etched away to form the grating film layer 202 on the substrate 201.

[0159] Remove the second patterned photoresist layer 2031.

[0160] In this embodiment, a mask layer is subsequently formed on the surface of the grating film layer, and two regions of the mask layer are patterned. The morphology of the mask layer in different grating regions is different. The morphology of the mask layer on the first grating region is different from that on the second grating region. For example, the morphology of the mask layer in the first grating region is adapted to the imprint master structure coupled into the grating region, and the morphology of the mask layer in the second grating region is adapted to the imprint master structure coupled out of the grating region. Using the patterned mask layer as a mask, the grating film layer is etched once to form a first grating structure on the first grating region and a second grating structure on the second grating region to form the binary grating structure. The morphology of the first grating structure is different from that of the second grating structure. The photoresist coating process, the mask layer deposition process, the mask layer patterning process, the grating film layer etching process, the selected materials, and the related height and thickness settings are all related to... Figure 2 To the diagram The embodiments described in 12 are the same and will not be repeated here.

[0161] In summary, in this embodiment provided by the present invention, grating film layers 202 of different heights are set in different grating regions by coating, and the binary grating structure is fabricated in a single etching process, greatly improving the efficiency and stability of the binary grating structure product. A method for determining the first difference is also provided, ensuring that the binary grating structure is formed in a single etching process. Precise control of the height and morphology of the grating units in the first and second grating structures is achieved by controlling the etching time. Of course, a nanoimprint etching scheme can also be used to combine the advantages of single etching and nanoimprint etching, further improving the efficiency and stability of the binary grating structure product.

[0162] Figures 17-19 This is a cross-sectional schematic diagram of another etching process for forming a binary grating structure according to an embodiment of the present invention. The difference between this embodiment and the two embodiments mentioned above is that a third grating structure is also etched simultaneously in the third grating region, and the third grating structure, together with the first grating structure and the second grating structure, constitutes the binary grating structure.

[0163] Please refer to Figure 17 In other embodiments of the present invention, the substrate 101 may further include a third grating region 1013.

[0164] The process of forming a grating film layer on the substrate surface, wherein the thickness of the grating film layer on the first grating region is greater than the thickness of the grating film layer on the second grating region or the third grating region, can refer to the process provided in any of the two embodiments described above, and will not be elaborated here.

[0165] Please refer to Figure 18 A mask layer is formed and patterned on the surface of the grating film layer 102. The morphology of the mask layer located on the first grating region 1011 is different from that of the mask layer located on the second grating region 1012 and the mask layer located on the third grating region 1013. The thickness of the patterned mask layer formed on the second grating region 1012 and the third grating region 1013 is different.

[0166] For example, the thickness H3 of the patterned mask layer formed on the third grating region 1013 is less than the thickness H2 of the patterned mask layer formed on the second grating region 1012.

[0167] The difference between the thickness of the grating film layer formed on the first grating region 1011 and the surface thickness of the grating film layer formed on the second grating region 1012 or the third grating region 1013 is a first difference value, the first difference value being:

[0168] △H=(h1-max(h2,h3))*S;

[0169] Where h1 is the height of the first grating structure; h2 is the height of the second grating structure; S is the etching selectivity ratio of the patterned mask layer to the grating film layer; h3 is the height of the third grating structure; and ΔH is the first difference.

[0170] In the above formula for the first difference ΔH=(h1-max(h2,h3))*S, for example, when a second grating structure 106 is formed on the second grating region 1012, and / or a height gradient of a third grating structure 107 is formed on the third grating region 1013, h2 is the maximum height value of the height gradient of the second grating structure 106, and h3 is the maximum height value of the height gradient of the third grating structure 107.

[0171] As can be further explained, exemplarily, when the second grating structure 106 in the second grating region includes grating structures of various depths, and / or when the third grating structure 107 in the third grating region includes grating structures of various depths, i.e., a height-gradient grating structure is formed, then when calculating the first difference ΔH, h2 refers to the maximum grating height value of the height-gradient second grating structure 106, and h3 refers to the maximum grating height value of the height-gradient third grating structure 107. When the depth of the second grating structure remains unchanged, and / or when the depth of the third grating structure remains unchanged, then h2 is the height of the second grating structure, and h3 is the height of the third grating structure.

[0172] Based on the different characteristics and corresponding design requirements of multiple grating structures, and considering various etching factors, in order to ensure that the grating structures of the three grating regions can be completely replicated through the same etching time, especially to ensure that when the first grating structure is formed in the first grating region at the same time, the structures of the second grating region and the second grating region exactly meet the design height, and also to ensure that the substrate 101 is not damaged by etching, and that the grating structures of the three regions at the preset height are simultaneously etched to form the preset grating height in one go, in one embodiment, the thickness H1 of the first patterned mask layer 1041 is H1 = h1*S; the thickness H2 of the second patterned mask layer 1042 is H2 > h2*S; and the thickness H3 of the third patterned mask layer 1043 on the third grating region 1013 satisfies: H3 > h3*S. It should be noted that H1, H2, H3, h1, h2, and h3 here are only for descriptive convenience and do not represent any numerical relationship. H3 represents the height of the third grating structure 107 formed on the third grating region 1013. Among them, H2 > H3, h2 > h3.

[0173] Of course, in some embodiments, H2≥H3, h2≥h3, which has better applicability based on different design heights.

[0174] Please refer to Figure 19 Using the patterned mask layer as a mask, the grating film layer 102 is etched once to form a first grating structure 105 on the first grating region 1011, a second grating structure 106 on the second grating region 1012, and a third grating structure 107 on the third grating region 1013, thus forming the binary grating structure. This binary grating structure includes three different grating structures, and the morphology of the first grating structure 105 is different from the morphology of the second grating structure 106 and the third grating structure 107. The fabrication process for this part is similar to that in the aforementioned embodiments and will not be described in detail here.

[0175] In one embodiment, the etching time for etching the grating film layer 102 once is the first etching time; the first etching time T = max(h2, h3) / V grating film layer 102 + ΔH / V mask layer; where T is the first etching time.

[0176] As can be seen, in this embodiment, the technical solution of the present invention is based on the difference in grating film thickness in different grating regions and the etching cutoff time is limited in order to ensure that the morphology of the first grating structure is completely etched, thereby achieving complete structural replication of multiple grating regions. Therefore, it provides an etching cutoff time for forming a binary grating structure in one etching operation, and at the same time achieves precise control of the height of grating units in the first grating structure, the second grating structure, and the third grating structure.

[0177] In summary, this embodiment of the invention sets grating film layers of different heights in different grating regions, achieving the fabrication of a binary grating structure in a single etching operation. Furthermore, it enables the fabrication of binary grating structures in three different grating regions in a single etching process. This significantly improves the efficiency and stability of the binary grating structure product while further enhancing production efficiency, avoiding calibration and efficiency issues associated with multiple imprinting and etching processes. It also allows for precise control of the grating unit height and morphology in the first, second, and third grating structures. Moreover, by employing a nanoimprint etching scheme, it combines the advantages of single-stage etching and nanoimprint etching, further enhancing the efficiency and stability of the binary grating structure product.

[0178] In further embodiments of the present invention, H3>H2, h3>h3 (not shown in the figure).

[0179] In one embodiment, a grating structure with grating units of different heights can also be formed in the second grating region to adjust the uniformity of efficiency.

[0180] When the binary grating structure refers to the binary grating structure in the diffractive waveguide, the third grating region refers to the pupil expansion region or the coupling region, and the third grating structure refers to the pupil expansion structure or the corresponding coupling structure.

[0181] In summary, the various embodiments provided by this invention can all achieve the fabrication of binary grating structures in a single imprint etching process, and can all improve the efficiency and stability of binary grating structure products, demonstrating significant progress.

[0182] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for forming a binary grating structure through a single etching process, characterized in that, include: A substrate is provided, the substrate comprising: a first grating region and a second grating region disposed sequentially; A grating film layer is formed on the surface of the substrate, and the thickness of the grating film layer on the first grating region is greater than the thickness of the grating film layer on the second grating region; A mask layer is formed on the surface of the grating film layer and the mask layer is patterned. The morphology of the mask layer located in the first grating region is different from the morphology of the mask layer located in the second grating region. Using the patterned mask layer as a mask, the grating film layer is etched once to form a first grating structure on the first grating region and a second grating structure on the second grating region, thus forming the binary grating structure, wherein the morphology of the first grating structure is different from that of the second grating structure.

2. The method for forming a binary grating structure by a single etching step according to claim 1, characterized in that, The mask layer located on the first grating region is flush with the surface of the mask layer located on the first grating region; the grating film layer is etched once to form a blazed grating, a trapezoidal irregular grating, or a serrated grating in the region where a higher grating film layer is formed, and a straight serrated grating in the region where a relatively lower grating film layer is formed.

3. The method for forming a binary grating structure by a single etching step according to claim 2, characterized in that, The difference between the thickness of the grating film layer formed on the first grating region and the surface thickness of the grating film layer formed on the second grating region is a first difference value. △H=(h1-h2)*S; Where h1 is the height of the first grating structure; h2 is the height of the second grating structure; S is the etching selection ratio of the patterned mask layer and the grating film layer; ΔH is the first difference value; S=V 掩膜层 / V 光栅膜层 ; Among them, V 掩膜层 The etching rate of the patterned mask layer; V 光栅膜层 It is the etching rate of the grating film.

4. The method for forming a binary grating structure by a single etching step according to claim 3, characterized in that, The etching time for etching the grating film layer in one pass is the first etching time; the first etching time T=h2 / V 光栅膜层 +△H / V 掩膜层 ; Where T is the first etching time.

5. The method for forming a binary grating structure by a single etching step according to claim 4, characterized in that, The height h1 of the first grating structure and the thickness H1 of the mask layer on the first grating region, and the height h2 of the second grating structure and the thickness H2 of the mask layer on the second grating region, respectively satisfy the following relationships: The thickness H1 of the mask layer on the first grating region: H1 = h1 * S; The thickness H2 of the mask layer on the second grating region: H2>h2*S.

6. The method for forming a binary grating structure by a single etching step according to claim 1, characterized in that, A method for forming a grating film layer on the surface of the substrate includes: A first grating film is formed on the surface of the substrate; A first patterned photoresist layer is formed on the surface of the first grating film in the second grating region; A second grating film of a first thickness is deposited on the surface of the first patterned photoresist layer and on the surface of the first grating film in the first grating region. Remove the first patterned photoresist layer.

7. The method for forming a binary grating structure by a single etching step according to claim 1, characterized in that, A method for forming a grating film layer on the surface of the substrate includes: A first grating film is formed on the surface of the substrate; A second patterned photoresist layer is formed on the surface of the first grating film in the first grating region; Using the second patterned photoresist layer as a mask, the first grating film with a first thickness located in the second grating region is etched away; Remove the second patterned photoresist layer.

8. The method for forming a binary grating structure by a single etching step according to claim 1 or 2, characterized in that, The substrate further includes a third grating region; when forming a first grating structure on the first grating region and a second grating structure on the second grating region, the method further includes: A third grating structure is formed in the third grating region, and the height of the third grating structure is different from the height of the second grating structure.

9. The method for forming a binary grating structure by a single etching step according to claim 8, characterized in that, The difference between the thickness of the grating film layer formed on the first grating region and the surface thickness of the grating film layer formed on the second grating region or the third grating region is a first difference value. △H=(h1-max(h2,h3))*S; Where h1 is the height of the first grating structure; h2 is the height of the second grating structure; S is the etching selectivity ratio of the patterned mask layer to the grating film layer; h3 is the height of the third grating structure; and ΔH is the first difference.

10. The method for forming a binary grating structure by a single etching step according to claim 8 or 9, characterized in that, The etching time for one etching of the grating film is the first etching time; the first etching time T = max(h2, h3) / V 光栅膜层 +△H / V 掩膜层 Where T is the first etching time.

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