Metal wire grid structure and method of manufacturing the same

Abstract

The application relates to the technical field of gratings, in particular to a metal wire grating structure and a preparation method thereof. The metal wire grating structure comprises, from bottom to top, a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are stacked in sequence; wherein the thickness of the metal grating layer is not greater than 30 nm; when incident light irradiates the metal wire grating structure from the side of the metal grating layer far from the transparent dielectric layer, part of the incident light is directly reflected by the metal grating layer to form first reflected light, and the remaining part of the incident light enters the transparent dielectric layer through the intervals between the metal wires, is reflected by the reflection layer, and then is emitted again through the transparent dielectric layer and the intervals between the metal wires to form second reflected light; the phase difference between the first reflected light and the second reflected light is an odd multiple of pi. The application is at least beneficial to improving the anti-pollution ability and the anti-abrasion ability of the grating under the premise of ensuring that the grating has high diffraction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of grating technology, and particularly relates to a metal wire grating structure and its preparation method. Background Technology

[0002] In modern industrial settings, particularly in metal processing, machine tool manufacturing, automated assembly, and precision measurement, optical gratings serve as core components for achieving precise position feedback. Their long-term stability and reliability directly determine the machining accuracy and production efficiency of the entire system. However, such environments are often affected by factors such as oil, coolant, and dust. Therefore, higher requirements are placed on the protective performance, anti-contamination capabilities, and cleanability of the optical gratings used as measurement references.

[0003] Currently, common protective measures mainly include material coating protection and structural encapsulation. Specifically, some related technologies propose physically isolating the external environment from the embossed microstructure on the grating surface by sequentially depositing a Cr film, a CrO film, and a transparent protective layer on the substrate, thereby achieving effective protection of the grating structure. Similarly, some measurement gratings also use transparent materials such as SiO2 and MgF2 deposited on the surface of the microstructure to form an isolation protection. Other related technologies focus on the materials themselves, using metal materials with low thermal expansion coefficients, such as Invar alloys, to prepare steel strip rulers as measurement references. The high mechanical strength of the materials themselves achieves anti-contamination and physical protection. Still other related technologies use mechanical encapsulation structures to place the reading head and the measurement grating in a relatively isolated working environment, thereby systematically improving anti-contamination and protection capabilities.

[0004] For the protective coating solution, the coating itself is prone to failure due to wear or scratches, and the interface between it and the grating relief structure may crack or peel under stress. It may also interfere with the optical signal measured by the reading head, affecting signal contrast. The metal grating solution, which uses materials such as Invar alloy or austenitic stainless steel to create a metal strip ruler, can provide basic protection due to the material's mechanical strength. However, in applications requiring ultra-high measurement accuracy, this solution has some inherent limitations. Specifically, on scales several meters long, ensuring the uniformity of the metal strip grating pitch is extremely difficult, and controlling the pitch error accuracy across the entire ruler length faces severe challenges. Secondly, due to limitations in manufacturing processes, the grating period is typically difficult to be lower than 10 μm. The larger period restricts further improvement in measurement resolution and is not conducive to subsequent high-magnification electron subdivision. In addition, the relief structure of the metal grating (such as tooth shape and steepness) is difficult to form precisely at the microscale, resulting in reduced diffraction efficiency, which in turn weakens the signal quality and stability that the readhead detector can receive, ultimately affecting the overall measurement performance of the system. For the closed structure scheme, the complexity, cost and volume of the system are increased, and maintenance is difficult once the sealed structure fails or becomes internally contaminated, without fundamentally improving the grating's resistance to contamination.

[0005] In summary, there is an urgent need in this field for a new solution that can fundamentally improve the anti-contamination capability of grating surfaces while avoiding the aforementioned defects. Summary of the Invention

[0006] In view of this, the present invention aims to provide a metal wire grid structure and its preparation method, which at least helps to improve the anti-fouling and anti-wear capabilities of the grating while ensuring that the grating has high diffraction efficiency.

[0007] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0008] This invention provides a metal wire grid structure, comprising: a substrate, a reflective layer, a transparent dielectric layer, and a metal grating layer stacked sequentially from bottom to top; wherein the metal grating layer includes a plurality of metal lines spaced apart on the surface of the transparent dielectric layer away from the reflective layer, and the thickness of the metal grating layer is not greater than 30 nm; when incident light irradiates the metal wire grid structure from the side of the metal grating layer away from the transparent dielectric layer, part of the incident light is directly reflected by the metal grating layer to form a first path of reflected light, and the remaining part of the incident light enters the transparent dielectric layer through the gaps between the metal lines, and after being reflected by the reflective layer, it is emitted again through the transparent dielectric layer and the gaps between the metal lines to form a second path of reflected light, and the phase difference between the first path of reflected light and the second path of reflected light is an odd multiple of π.

[0009] Furthermore, the thickness of the metal grating layer is in the range of 5nm to 30nm.

[0010] Furthermore, the material of the metal grating layer is chromium or chromium oxide.

[0011] Furthermore, the aspect ratio of the metal grating layer is in the range of 0.3 to 0.7, and the grating line density is in the range of 50 g / mm to 500 g / mm.

[0012] Furthermore, the reflective layer is a metal film, a multilayer dielectric film, or a composite film composed of a metal material and a dielectric material. The metal film is made of at least one of gold, silver, or aluminum. The multilayer dielectric film is composed of at least two high-refractive-index materials and low-refractive-index materials selected from SiO2, Ta2O5, HfO2, and TiO2, stacked alternately. The composite film is composed of a combination of a metal material, a high-refractive-index dielectric material, and a low-refractive-index dielectric material.

[0013] Furthermore, the material of the transparent dielectric layer includes at least one of SiO2, Ta2O5, HfO2 and TiO2, and the transmittance of the transparent dielectric layer at the working wavelength is greater than 95%.

[0014] Another aspect of this invention provides a method for fabricating a metal wire grid structure, comprising: forming a substrate, a reflective layer, a transparent dielectric layer, and a metal grating layer stacked sequentially from bottom to top; the metal grating layer comprising a plurality of metal lines spaced apart on the surface of the transparent dielectric layer away from the reflective layer; the thickness of the metal grating layer being no greater than 30 nm; when incident light irradiates the metal wire grid structure from the metal grating layer away from the transparent dielectric layer, part of the incident light is directly reflected by the metal grating layer to form a first path of reflected light; the remaining part of the incident light enters the transparent dielectric layer through the gaps between the metal lines, and after being reflected by the reflective layer, it is emitted again through the transparent dielectric layer and the gaps between the metal lines to form a second path of reflected light; the phase difference between the first path of reflected light and the second path of reflected light is an odd multiple of π.

[0015] Furthermore, forming the substrate, reflective layer, transparent dielectric layer and metal grating layer stacked sequentially from bottom to top includes: first forming the substrate, reflective layer and transparent dielectric layer stacked sequentially from bottom to top; forming a photoresist layer with a deposition window on the transparent dielectric layer; depositing a metal layer, and then removing the photoresist layer to form the metal grating layer.

[0016] Furthermore, forming a photoresist layer with a deposition window on the transparent dielectric layer includes: spin-coating photoresist onto the transparent dielectric layer, with the thickness of the photoresist controlled within the range of 100 nm to 1 μm; baking at 90 °C for 1 min to 30 min after coating; exposing for 100 s using interference exposure or 200 s using projection exposure; immersing the exposed sample in NaOH solution for 60 s to obtain a photoresist layer with a deposition window; depositing a metal layer and then removing the photoresist layer includes: depositing a chromium layer with a thickness in the range of 5 nm to 30 nm using electron beam evaporation; placing the chromium-plated sample in acetone or alcohol solution to dissolve the photoresist layer and subsequently remove the chromium layer on the surface of the photoresist layer, ultimately forming a metal grating layer.

[0017] Furthermore, forming the substrate, reflective layer, transparent dielectric layer and metal grating layer stacked sequentially from bottom to top includes: first forming the substrate, reflective layer and transparent dielectric layer stacked sequentially from bottom to top; forming a metal layer on the transparent dielectric layer; forming a photoresist layer with etching windows on the metal layer; etching away a portion of the metal layer corresponding to the etching windows, and then removing the photoresist layer to obtain the metal grating layer.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects: The present invention addresses the shortcomings of existing measurement gratings in terms of anti-fouling ability and structural durability, and provides a grating structure with excellent anti-fouling ability and high diffraction efficiency. By preparing an extremely shallow metal wire grating with a thickness of nanometers, the grating surface is made to be flat, which significantly reduces the adhesion and retention of pollutants on the surface of the grating structure. This makes it difficult for pollutants such as dust, oil and water droplets to adhere to the nearly flat surface, thus giving the grating structure excellent anti-fouling performance. In addition, the near-planar surface structure of the grating structure is easy to wipe and clean, and is not easily damaged by wiping and abrasion, while still maintaining high diffraction efficiency.

[0019] In the metal wire grid structure provided by this invention, when incident light irradiates the surface of the grating, part of the light is directly reflected by the metal wire grid on the surface, and the other part of the light passes through the wire grid into the transparent dielectric layer, and returns after being reflected by the bottom reflective layer. By precisely controlling the thickness of the transparent dielectric layer, the two parts of reflected light can be made to have opposite phases, thereby suppressing the overall reflected energy flow through "interference cancellation" and transferring more energy to the diffraction order, effectively improving the diffraction efficiency. Therefore, even if the metal grating layer is designed to be relatively thin, a high diffraction efficiency can be achieved, which is beneficial to improving the anti-fouling and anti-wear capabilities of the grating while ensuring that the grating has a high diffraction efficiency. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A schematic diagram of a metal wire grid structure according to an embodiment of the present invention;

[0022] Figure 2 A diffraction efficiency curve of a metal wire grid structure as described in an embodiment of the present invention;

[0023] Figure 3 A diffraction efficiency curve of another metal wire grid structure described in the embodiment of the present invention;

[0024] Figure 4 A schematic diagram of another metal wire grid structure described in an embodiment of the present invention;

[0025] Figure 5 A diffraction efficiency curve of another metal wire grid structure described in an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] refer to Figure 1 This invention provides a metal wire grid structure, comprising: a substrate 1, a reflective layer 2, a transparent dielectric layer 3, and a metal grating layer 4 stacked sequentially from bottom to top; wherein, the metal grating layer 4 includes a plurality of metal lines spaced apart on the surface of the transparent dielectric layer 3 away from the reflective layer 2, and the thickness of the metal grating layer 4 is not greater than 30 nm; when incident light irradiates the metal wire grid structure from the side of the metal grating layer 4 away from the transparent dielectric layer 3, part of the incident light is directly reflected by the metal grating layer 4 to form a first path of reflected light, and the remaining part of the incident light enters the transparent dielectric layer 3 through the gaps between the metal lines, and after being reflected by the reflective layer 2, it is emitted again through the transparent dielectric layer 3 and the gaps between the metal lines to form a second path of reflected light, and the phase difference between the first path of reflected light and the second path of reflected light is an odd multiple of π.

[0032] The phase difference between the first and second reflected beams is an odd multiple of π, which can produce an opposite phase effect between the first and second reflected beams. This effectively suppresses the intensity of the reflection order through "interference cancellation" and, based on the law of conservation of energy, transfers more energy to the diffraction order. As a result, the top metal grating layer 4 mainly undertakes the functions of reflection and light blocking. Therefore, the thickness of the metal grating layer 4 can be designed to be extremely thin, thereby making the surface of the metal wire grating structure more planar. This not only helps to achieve stable optical performance but also significantly improves the device's resistance to contamination and ease of maintenance.

[0033] In some embodiments, substrate 1 may be selected as microcrystalline glass with a low coefficient of thermal expansion.

[0034] In the metal grating structure, the substrate serves as the carrier of the grating structure to ensure the dimensional stability of the overall structure under working conditions. The reflective layer 2 is used to enhance the reflection capability of incident light, thereby improving the overall diffraction efficiency. The transparent dielectric layer 3 is used to regulate the phase relationship between the direct reflected light of the metal grating layer 4 and the reflected light reflected by the reflective layer 2, thereby achieving light field matching. The metal grating layer 4 mainly realizes the diffraction of incident light, and due to its extremely thin characteristics, the surface tends to be planar, which has both anti-pollution and easy maintenance characteristics.

[0035] In some embodiments, the reflective layer 2 is a metal film, a multilayer dielectric film, or a composite film composed of a metal material and a dielectric material. The metal film is made of at least one of gold, silver, or aluminum. The multilayer dielectric film is composed of at least two high-refractive-index materials and low-refractive-index materials selected from SiO2, Ta2O5, HfO2, and TiO2, stacked alternately. The composite film is composed of a combination of a metal material, a high-refractive-index dielectric material, and a low-refractive-index dielectric material. The metal material can be Au, and the high-refractive-index dielectric material and the low-refractive-index dielectric material can be selected from SiO2, Ta2O5, HfO2, and TiO2.

[0036] In some embodiments, the material of the transparent dielectric layer 3 includes at least one of SiO2, Ta2O5, HfO2 and TiO2, and the transmittance of the transparent dielectric layer 3 at the working wavelength is greater than 95%. That is, the transparent dielectric layer 3 is essentially transparent to the working wavelength.

[0037] In some embodiments, the thickness of the metal grating layer 4 is in the range of 5 nm to 30 nm.

[0038] In some embodiments, the material of the metal grating layer 4 is chromium or chromium oxide.

[0039] In some embodiments, the fill factor (fill factor = linewidth: period) of the metal grating layer 4 is in the range of 0.3 to 0.7, and the grating line density is in the range of 50 g / mm to 500 g / mm. Under this combination of parameters, the metal wire grating structure can achieve a diffraction efficiency of not less than 10% in the target wavelength band.

[0040] Understandably, for the parameter design of the metal grating layer 4, the grating parameters that achieve high diffraction efficiency within a specific operating wavelength range can be determined by using a rigorous coupled-wave calculation method according to application requirements.

[0041] The following section uses a metal wire grating structure with a period of 2.048 μm and an operating wavelength of 850 nm as an example to explain its specific parameters in detail. The metal wire grating structure has an operating order of -1 and an incident angle of 0°. The substrate 1 is made of microcrystalline glass with a low coefficient of thermal expansion. The reflective layer 2 is made of aluminum and has a thickness of 100 nm. The transparent dielectric layer 3 is made of SiO2 and has a thickness of 120 nm. The metal grating layer 4 has an aspect ratio of 0.5 and a thickness of 30 nm. The diffraction efficiency curve is shown below. Figure 2 As shown, under 850nm incident light conditions, within a 20° angle deviation range, the peak diffraction efficiencies of both the TE (Transverse Electric) and TM (Transverse Magnetic) polarization states are higher than 27% and not lower than 23%. In another embodiment, the thickness of the reflective layer 2 is 100nm, the thickness of the metal grating layer 4 is 5nm, the aspect ratio of the metal grating layer 4 is 0.5, and the thickness of the transparent dielectric layer 3 is 130nm. Under the 0°~20° incident light conditions, the TE and TM diffraction efficiencies are also higher than 10%, as shown in the diffraction efficiency curves. Figure 3 As shown.

[0042] In some embodiments, the period of the metal wire grid structure is 2.048 μm, the operating wavelength is 850 nm, the operating order is -1, and the incident angle is 0°. The film structure of the metal wire grid structure is S|A(LH)4BT|C, where A(LH)4 represents the reflective layer 2, A represents aluminum with a thickness of 100 nm, (LH)4 represents a combination of four pairs of Ta2O5 and SiO2 with a thickness of one-quarter of the reference wavelength, the physical thickness of Ta2O5 is 97.48 nm, the physical thickness of SiO2 is 141.95 nm, B represents the transparent dielectric layer 3, the transparent dielectric layer 3 is SiO2 with a physical thickness of 230 nm, T represents the metal grating layer 4, the metal grating layer 4 is a chromium layer with a physical thickness of 30 nm, S represents the semi-infinite microcrystalline substrate 1, C represents the semi-infinite air layer, the aspect ratio of the metal grating layer 4 is 0.5, and the metal wire grid structure is as follows. Figure 4 As shown, the diffraction efficiencies of both TE and TM under incident conditions of 0°~20° are higher than 23%, with peak efficiencies reaching 38%. The diffraction efficiency curves are shown below. Figure 5 As shown.

[0043] Another aspect of this invention provides a method for fabricating a metal wire grid structure, comprising: forming a substrate 1, a reflective layer 2, a transparent dielectric layer 3, and a metal grating layer 4 stacked sequentially from bottom to top; the metal grating layer 4 includes a plurality of metal lines spaced apart on the surface of the transparent dielectric layer 3 away from the reflective layer 2; the thickness of the metal grating layer 4 is not greater than 30 nm; when incident light irradiates the metal wire grid structure from the side of the metal grating layer 4 away from the transparent dielectric layer 3, part of the incident light is directly reflected by the metal grating layer 4 to form a first path of reflected light; the remaining part of the incident light enters the transparent dielectric layer 3 through the gaps between the metal lines, and after being reflected by the reflective layer 2, it is emitted again through the transparent dielectric layer 3 and the gaps between the metal lines to form a second path of reflected light; the phase difference between the first path of reflected light and the second path of reflected light is an odd multiple of π.

[0044] In some embodiments, forming a substrate 1, a reflective layer 2, a transparent dielectric layer 3, and a metal grating layer 4 stacked sequentially from bottom to top includes: first forming a substrate 1, a reflective layer 2, and a transparent dielectric layer 3 stacked sequentially from bottom to top; forming a photoresist layer with a deposition window on the transparent dielectric layer 3; depositing a metal layer; and then removing the photoresist layer to form the metal grating layer 4.

[0045] In some embodiments, forming a substrate 1, a reflective layer 2, and a transparent dielectric layer 3 stacked sequentially from bottom to top includes: providing a substrate; cleaning the substrate 1 using ultrasonic or megaphonic cleaning to remove surface contaminants and particles; and then sequentially depositing the reflective layer 2 and the transparent dielectric layer 3 on the surface of the substrate 1 using electron beam evaporation, ion beam sputtering, thermal evaporation, or magnetron sputtering. The reflective layer 2 has high reflectivity to the incident wavelength, the transparent dielectric layer 3 has high transmittance to the incident wavelength, and the thickness of the transparent dielectric layer 3 satisfies the aforementioned phase-matching condition for high diffraction efficiency.

[0046] In some embodiments, forming a photoresist layer with a deposition window on the transparent dielectric layer 3 includes: spin-coating photoresist onto the transparent dielectric layer 3, wherein the thickness of the photoresist is controlled within the range of 100 nm to 1 μm; baking at 90°C for 1 min to 30 min after coating; exposing for 100 s using interference exposure or 200 s using projection exposure; immersing the exposed sample in NaOH solution for 60 s to obtain a photoresist layer with a deposition window; depositing a metal layer and then removing the photoresist layer includes: depositing a chromium layer with a thickness in the range of 5 nm to 30 nm using electron beam evaporation; placing the chromium-plated sample in acetone or alcohol solution to dissolve the photoresist layer and subsequently remove the chromium layer on the surface of the photoresist layer, ultimately forming a metal grating layer 4.

[0047] In some embodiments, the aforementioned exposure steps may also be replaced by electron beam exposure, laser direct writing, or mask exposure.

[0048] In other embodiments, forming a substrate 1, a reflective layer 2, a transparent dielectric layer 3, and a metal grating layer 4 stacked sequentially from bottom to top includes: first forming a substrate 1, a reflective layer 2, and a transparent dielectric layer 3 stacked sequentially from bottom to top; forming a metal layer on the transparent dielectric layer 3; forming a photoresist layer with etching windows on the metal layer; etching away a portion of the metal layer corresponding to the etching windows; and then removing the photoresist layer to obtain the metal grating layer 4.

[0049] The diffraction efficiency of the metal wire grating structure provided by this invention mainly depends on the phase modulation capability of the transparent dielectric layer 3 on the incident light. This metal wire grating structure can maintain high diffraction efficiency even under wide-angle incident light, which is beneficial to improving the flexibility and tolerance of the mechanical adjustment of the grating ruler reading head. In addition, since the thickness of the top metal grating layer 4 can be controlled to a few nanometers, that is, it is made extremely thin, making the height of the grating surface close to a plane. This significantly reduces the tendency and retention of contaminants on the surface, making it difficult for contaminants such as dust, oil, and water droplets to accumulate on the nearly flat surface. As a result, the grating has excellent anti-fouling performance and is easy to wipe clean. During the cleaning process, the microstructure of the grating is not easily damaged by friction, thus maintaining high diffraction efficiency during long-term use.

[0050] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0051] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A wire grid structure, characterized by The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. The metal grating layer comprises a plurality of metal wires which are arranged at intervals on the surface of the transparent dielectric layer away from the reflection layer, and the thickness of the metal grating layer is not greater than 30nm. When incident light irradiates the metal wire grating structure from the side of the metal grating layer away from the transparent dielectric layer, part of the incident light is directly reflected by the metal grating layer to form first reflected light, and the remaining part of the incident light enters the transparent dielectric layer through the intervals between the metal wires, is reflected by the reflection layer, and then exits again through the transparent dielectric layer and the intervals between the metal wires to form second reflected light, and the phase difference between the first reflected light and the second reflected light is an odd multiple of pi. The thickness of the metal grating layer is in the range of 5nm to 30nm.

2. The metal wire grid structure of claim 1, wherein, The material of the metal grating layer is chromium or chromium oxide.

3. The metal wire grid structure of claim 1, wherein, The line width ratio of the metal grating layer is in the range of 0.3 to 0.7, and the grating line density is in the range of 50g / mm to 500g / mm.

4. The metal wire grid structure of claim 1, wherein, The reflection layer is a metal film, a multilayer dielectric film or a composite film composed of a metal material and a dielectric material, the material of the metal film comprises at least one of gold, silver or aluminum, the multilayer dielectric film is composed of at least two high refractive index materials and low refractive index materials selected from SiO2, Ta2O5, HfO2 and TiO2 which are alternately stacked, and the composite film is composed of a metal material, a high refractive index dielectric material and a low refractive index dielectric material.

5. The metal wire grid structure of claim 1, wherein, The material of the transparent dielectric layer comprises at least one of SiO2, Ta2O5, HfO2 and TiO2, and the transmittance of the transparent dielectric layer at the working wavelength is greater than 95%.

6. The metal wire grid structure of claim 1, wherein, The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top.

7. A method of manufacturing a metal wire grid structure, characterized by, The metal grating layer comprises a plurality of metal wires which are arranged at intervals on the surface of the transparent dielectric layer away from the reflection layer, and the thickness of the metal grating layer is not greater than 30nm. When incident light irradiates the metal wire grating structure from the side of the metal grating layer away from the transparent dielectric layer, part of the incident light is directly reflected by the metal grating layer to form first reflected light, and the remaining part of the incident light enters the transparent dielectric layer through the intervals between the metal wires, is reflected by the reflection layer, and then exits again through the transparent dielectric layer and the intervals between the metal wires to form second reflected light, and the phase difference between the first reflected light and the second reflected light is an odd multiple of pi. The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top.

8. The method of claim 7, wherein the metal wire grid structure is formed by a process comprising: The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top.

9. The method of claim 8, wherein the metal wire grid structure is formed by a process comprising: The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. The application relates to a metal grating structure, which comprises a substrate, a reflection layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top. 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The application relates to a metal grating structure immersing the exposed sample in a NaOH solution for 60s to obtain a photoresist layer with a deposition window; the method for depositing a metal layer and removing the photoresist layer comprises: coating a chromium layer with a thickness in the range of 5nm-30nm by using an electron beam evaporation method, immersing the sample after chromium coating in an acetone or alcohol solution to dissolve the photoresist layer and remove the chromium layer on the surface of the photoresist layer, and finally forming the metal grating layer.

10. The method of claim 7, wherein the metal wire grid structure is prepared by a method comprising: forming a substrate, a reflective layer, a transparent dielectric layer and a metal grating layer which are sequentially stacked from bottom to top comprises: firstly forming a substrate, a reflective layer and a transparent dielectric layer which are sequentially stacked from bottom to top; forming a metal layer on the transparent dielectric layer; forming a photoresist layer with an etching window on the metal layer; etching and removing the metal layer corresponding to the etching window, and then removing the photoresist layer to obtain the metal grating layer.

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