Mask plate structure, method for forming optical structure, and diffraction optical waveguide

Abstract

A mask plate structure, an optical structure and a method for forming the same, the method comprising: providing a substrate, the substrate comprising one or more optical structure regions; providing a mask plate structure, the mask plate structure comprising: a first mask plate and a second mask plate arranged in a direction perpendicular to the substrate surface; providing a target material, arranged above the substrate; arranging the mask plate structure between the target material and the substrate, the second mask plate contacting the substrate, the second through hole corresponding to the optical structure region, and the first through hole corresponding to the target material; forming a material layer with a continuously gradient thickness on the optical structure region by bombarding the target material, so as to achieve continuous thickness variation of the optical structure and accurately control the same.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a mask plate structure, an optical structure and a forming method thereof. Background Art

[0002] As a key optical component in augmented reality display technology, diffractive waveguides are favored by the industry for their wide eye movement range, compact size, and high mass production capabilities. To achieve uniform field of view, color uniformity, and efficient optical transmission, the design and fabrication of diffractive waveguides are constantly being explored. In particular, achieving high-efficiency diffractive waveguide fabrication has become a key research focus within the industry.

[0003] In semiconductor processing, how to optimize optical structures with continuously varying thickness is an ongoing problem that needs to be solved. Summary of the Invention

[0004] The present invention provides a mask plate structure, an optical structure and a forming method thereof, which solves the technical problem of precise control of continuous thickness change of the optical structure.

[0005] To solve the above technical problems, an embodiment of the present invention provides a mask plate structure, including: a first mask plate, wherein the first mask plate has a first through hole passing through the first mask plate; a second mask plate, wherein the second mask plate has a second through hole passing through the second mask plate; there is a spacing between the first mask plate and the second mask plate, and the first mask plate and the second mask plate are used to form a material layer with a continuously gradient thickness in the second through hole area.

[0006] Optionally, the first mask plate and the second mask plate are connected via a connecting portion to form an integrated structure, and the second mask plate is attached to the substrate.

[0007] Alternatively, in some other embodiments, the first mask plate and the second mask plate are independently formed on a substrate, and the second mask plate is in contact with the substrate.

[0008] Optionally, a projection range of the first through hole projected onto the second mask plate is located within the second through hole; and the first mask plate and the second mask plate are arranged in parallel.

[0009] Optionally, a center line of the first through hole coincides with a center line of the second through hole.

[0010] Correspondingly, the technical solution of the present invention also provides a method for forming a grating structure in a diffraction optical waveguide, comprising: providing a substrate, the substrate comprising one or more optical structure regions; providing a mask plate structure, the mask plate structure comprising: a first mask plate and a second mask plate arranged in a direction perpendicular to the surface of the substrate; providing a target material, arranged above the substrate; arranging the mask plate structure between the target material and the substrate, the second mask plate in contact with the substrate, the second through hole corresponding to the optical structure region, and the first through hole corresponding to the target material; forming a material layer with a continuously gradient thickness on the optical structure region by bombarding the target material.

[0011] Optionally, the material layer includes an effective area and an ineffective area; the formation method further includes: forming a protective layer on the surface of the material layer, the surface of the protective layer is a flat surface, and the protective layer exposes the surface of the ineffective area; using the protective layer as a mask to remove the ineffective area; forming a patterned mask layer on the surface of the protective layer; etching the protective layer and the effective area using the patterned mask layer as a mask, so that the effective area is formed into an optical structure on the optical structure area of ​​the substrate, the protective layer is located on the optical structure, and the thickness of the plurality of optical structures gradually increases along the edge of the optical structure area toward the center; after the optical structure is formed, the protective layer is removed.

[0012] Optionally, the formation method also includes: forming a patterned mask layer on the surface of the material layer; etching the material layer using the patterned mask layer as a mask to form a grating structure on the optical structure area, and the thickness of several of the optical structures gradually increases along the edge of the optical structure area toward the center.

[0013] Correspondingly, the technical solution of the present invention also provides a diffraction optical waveguide, which at least includes a coupling-out optical structure region and / or a turning optical structure region, and the grating structure in the coupling-out optical structure region or the turning optical structure region is prepared by the above-mentioned method for forming the optical structure to obtain the optical structure region.

[0014] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0015] The mask plate structure of the technical solution of the present invention, the first mask plate and the second mask plate are used to form a material layer with continuously changing thickness in the second through-hole area. The mask plate structure can form a material layer with continuously changing thickness on the substrate. By designing the mask plate structure, the thickness change of the material layer at different positions can be accurately controlled to form an optical structure with continuously changing thickness. On the one hand, based on this structural design, the diffraction efficiency of the optical structure at different positions can be modulated to improve the display uniformity of the optical structure at different positions and improve the display effect; on the other hand, the design of the structure can also improve the display appearance of the optical structure. The design of continuously changing thickness can prevent sudden changes in thickness at different positions. Such a design improves the dimensional accuracy and visual effect of the optical structure.

[0016] Furthermore, the centerline of the first through-hole in the first mask coincides with the centerline of the second through-hole in the second mask, and the projection of the first through-hole onto the second mask falls within the range of the second through-hole. This mask structure enables the formation of a material layer with continuously varying thickness on the substrate, enabling precise control of the display appearance of the optical structure and improving the dimensional accuracy and visual quality of the optical structure.

[0017] The method for forming a grating structure in a diffractive optical waveguide of the technical solution of the present invention is to arrange the above-mentioned mask plate structure between the target material and the substrate, the second through hole corresponds to the optical structure area, and the first through hole corresponds to the target material, and the position of the mask structure and the sputtering process are controlled to form a material layer with continuously varying thickness on the substrate, and to accurately control the display appearance of the optical structure, especially to prevent sudden stripes from occurring between different optical structure areas, so that the thickness of different optical structure areas is continuously and gradually varying, thereby improving the display appearance of the formed optical structure; and further, based on this method, a diffractive optical waveguide is formed. A grating structure is formed to form a grating structure with a continuously gradient depth, with different grating structures having different depths. On the one hand, this method modulates the diffraction efficiency of the prepared grating structure at different positions, so that the grating structure has a continuously gradient diffraction efficiency at different positions, thereby improving the display uniformity of the diffraction light waveguide and improving the display effect of the waveguide. On the other hand, the diffraction light waveguide obtained in this way has different grating structures with continuously gradient depths at different positions, which is different from the existing partitioned structure in terms of display appearance, thereby preventing the visual difference caused by sudden thickness changes at different positions and achieving a better visual appearance effect.

[0018] Furthermore, by adjusting the first spacing between the first mask plate and the second mask plate, and adjusting the size of the first area of ​​the first through hole, the thickness of the material layer at each position on the optical structure area is precisely adjusted, and the design of the thickness continuous gradient structure is controlled to improve the display efficiency of the optical structure at different positions and improve the display uniformity, thereby improving the display effect of the optical structure. At the same time, the display appearance of the optical structure is improved, and the dimensional accuracy and visual effect of the optical structure are enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 and Figure 2 is a structural schematic diagram of a mask plate structure in an embodiment of the present invention;

[0020] Figures 3 to 13 1 is a structural diagram of the optical structure formation process in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] As described in the background art, how to optimize optical structures with continuously varying thickness is a problem that needs to be continuously solved.

[0022] For some optical structures, gradual thickness changes are required to modulate the performance parameters of the optical structure to achieve the desired function. Typically, the thickness gradient difference of such optical structures varies within tens of nanometers. Precisely controlling the formation of continuously modulated thickness structures to achieve this continuous thickness gradient is a difficult problem to solve, especially for nanometer-scale thickness gradients, which is a technical problem that urgently needs to be solved. For example, the grating structure in a diffractive optical waveguide requires continuous and gradual modulation of the grating depth to adjust the diffraction efficiency distribution of the grating structure.

[0023] Furthermore, methods for forming optical structures with continuously varying thicknesses can easily create abrupt changes in thickness between different gradient regions. These changes, defined as the locations where the thickness of the optical structure suddenly changes, can affect the appearance of the resulting product, making it less visually acceptable to consumers. Therefore, it is necessary to improve the generation of these changes and precisely control the continuous thickness variation of the optical structure. For example, the grating structure in a diffractive waveguide requires continuous, gradual modulation of the grating depth to enhance visibility.

[0024] In order to solve the above problems, the embodiments of the present invention provide a mask plate structure, a method for forming an optical structure, and a diffraction optical waveguide. By setting the mask plate structure between the target material and the substrate, the second through hole corresponds to the optical structure area, and the first through hole corresponds to the target material, a material layer with continuously varying thickness can be formed on the substrate, and the thickness variation of different areas can be accurately controlled to form an optical structure with continuously varying thickness. While modulating the diffraction efficiency of the optical structure, this technical means is used to improve the appearance of the optical structure, so that sudden stripes are less likely to appear between different optical structure areas. The optical structure can visually obtain a better appearance effect and has a higher diffraction efficiency, thereby improving the display effect.

[0025] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0026] Figure 1 and Figure 2 Schematic diagram of the structure of the mask plate in an embodiment of the present invention.

[0027] Please refer to Figure 1 and Figure 2 , Figure 2 for Figure 1 A top view of Figure 1 for Figure 2 Schematic diagram of the structure along the section line BB1, the mask plate structure includes: a first mask plate 101, the first mask plate 101 has a first through hole 104 passing through the first mask plate 101; a second mask plate 102, the second mask plate 102 has a second through hole 105 passing through the second mask plate 102; there is a gap between the first mask plate 101 and the second mask plate 102, the first mask plate 101 and the second mask plate 102 are used to form a material layer with a continuous and gradual thickness in the area of ​​the second through hole 105. Figure 6 The material layer 203 is shown with a continuously graded thickness.

[0028] In this embodiment, the mask plate structure further includes: a connecting portion 103, wherein the connecting portion 103 connects the first mask plate 101 and the second mask plate 102, and the first mask plate 101 and the second mask plate 102 are connected to form an integrated structure through the connecting portion 103, and the second mask plate 102 is attached to the substrate.

[0029] In other embodiments, the mask plate structure may not include the connecting portion, the first mask plate and the second mask plate are independently formed on a substrate, and the second mask plate is in contact with the substrate.

[0030] The above two embodiments of the mask plate structure are both within the scope of protection of the present invention. As long as they do not deviate from the purpose of protection claimed by the present invention, that is, to achieve a material layer with continuously gradient thickness, no limitation is imposed on the connection method of the mask structure.

[0031] In this embodiment, the center line L1 of the first through hole 104 coincides with the center line L2 of the second through hole 105, and the projection range of the first through hole 104 on the second mask plate 101 is within the range of the second through hole 105, so as to accurately control the process of realizing the continuous thickness gradient material layer.

[0032] In this embodiment, the first mask plate 101 and the second mask plate 102 are arranged in parallel to form a material layer with a preset thickness variation.

[0033] The first mask plate 101 and the second mask plate 102 are arranged in parallel, which can reduce the risk of interference between the mask plate structure and the material source or the machine chamber, and facilitates the adjustment of the thickness variation trend of the material formed in the second through hole 105 .

[0034] In this embodiment, the area of ​​the first through hole 104 is smaller than the area of ​​the second through hole 105 .

[0035] The shape of the first through hole 104 includes a circle, an ellipse, a rectangle, a trapezoid or a polygon, and the number of sides of the polygon is greater than or equal to 5.

[0036] In this embodiment, the shape of the first through hole 104 includes a circle.

[0037] The second through hole 105 has a shape of a rectangle, a trapezoid or a polygon, and the number of sides of the polygon is greater than or equal to 5.

[0038] In one embodiment, the shape of the first through hole 104 is the same as the shape of the second through hole 105. The shape of the first through hole 104 and the shape of the second through hole 105 include a rectangle, a trapezoid or a polygon.

[0039] In another embodiment, the shape of the first through hole 104 is different from the shape of the second through hole 105 .

[0040] The material of the mask plate structure includes metal or metal alloy, the metal alloy includes stainless steel, iron-nickel alloy, and the metal includes iron, aluminum or titanium.

[0041] Figures 3 to 13 1 is a structural diagram of the optical structure formation process in an embodiment of the present invention.

[0042] Please refer to Figure 3 and Figure 4 , Figure 3 for Figure 4 A top view of Figure 4 for Figure 3 A cross-sectional structural diagram of a substrate 200 is provided, wherein the substrate 200 includes one or more optical structure areas 201.

[0043] The optical structure region 201 is a region where a material layer is subsequently formed.

[0044] like Figure 3 As shown, Figure 3 A single optical structure region 201 is schematically shown, and a continuous region 20 is schematically shown, wherein the continuous region 20 includes two or more optical structure regions 201, Figure 3 The continuous area 20 in the figure schematically shows three different optical structure areas 201. The different optical structure areas 201 shown in the figure are only examples and do not constitute a limitation on the structure and position of the optical structure 201. If multiple optical structure areas 201 are independently separated, or divided into regions, or have other structural shapes, etc., they all belong to the optical structure areas indicated in the present invention. Figure 3 The multiple structural areas shown are for simple illustration only.

[0045] The substrate 200 may be made of an inorganic material or a semiconductor material. The inorganic material may include quartz, and the semiconductor material may include silicon, silicon carbide, titanium oxide, lithium niobate, germanium, gallium arsenide, and the like.

[0046] Please refer to Figure 5 , providing a mask plate structure, the mask plate structure comprising: a first mask plate 101 and a second mask plate 102 arranged in a direction perpendicular to the surface of the substrate 200.

[0047] For the specific setting of the mask plate structure, please refer to Figure 1 and Figure 2 The text description of the Chinese characters will not be repeated here.

[0048] Please continue to refer to Figure 5 There is a first distance H' between the first mask plate 101 and the second mask plate 102, the first through hole 104 has a first aperture R1, and the second through hole 105 has a second aperture R2, and the first aperture R1 is smaller than the second aperture R2.

[0049] The first aperture R1 is the maximum size of the first through hole 104 , and the second aperture R2 is the maximum size of the second through hole 105 .

[0050] In this embodiment, the first aperture R1 ranges from 6 mm to 10 mm.

[0051] In this embodiment, the second aperture R2 ranges from 10 mm to 50 mm.

[0052] In this embodiment, the first distance H' ranges from 25 mm to 35 mm.

[0053] In this embodiment, the first mask plate 101 has a first thickness d1 , and the first thickness d1 ranges from 2 micrometers to 500 micrometers.

[0054] In this embodiment, the second mask plate 102 has a second thickness d2 , and the second thickness d2 is in a range of 2 micrometers to 500 micrometers.

[0055] The first through hole 104 has a first area S1 , and the second through hole 105 has a second area S2 .

[0056] Please refer to Figure 6 , providing a target material 202, which is arranged above the substrate 200; setting the mask plate structure between the target material 202 and the substrate 200, the second mask plate 102 is adjacent to the substrate 200, the second through hole 105 corresponds to the optical structure area 201, and the first through hole 104 corresponds to the target material 202; by bombarding the target material 202, a material layer 203 with a continuously gradient thickness is formed on the optical structure area 201.

[0057] In this embodiment, the thickness of the material layer 203 changes continuously and gradually, including: the thickness of the material layer 203 gradually increases from the edge to the center of the optical structure area 201.

[0058] The continuous thickness gradient defined in the present invention does not require absolute continuity in the mathematical sense. The thickness change difference between adjacent positions of the material layer can be less than 1%, 3% or 5%, etc. The actual thickness change difference can be determined according to the performance requirements of the actual product.

[0059] In this embodiment, the second mask plate 102 is adjacent to the substrate 200 , which includes: the second mask plate 102 is disposed on the substrate 200 and in contact with the substrate 200 .

[0060] In other embodiments, the second mask plate is adjacent to the substrate, including: there is a distance between the second mask plate and the substrate, and the second mask plate is not in direct contact with the substrate.

[0061] In this embodiment, the surface of the target 202 is disposed opposite to the surface of the substrate 200 , that is, the sputtering surface of the target 202 is opposite to the surface of the substrate 200 .

[0062] Please combine Figure 3Continue to refer Figure 6 , the second through hole 105 corresponds to the optical structure area 201, including: the second through hole 105 corresponds to a single optical structure area 201.

[0063] In this embodiment, the second through hole 105 corresponds to the optical structure area 201 , including: the second through hole 105 has the same shape and area as the optical structure area 201 ; and the center line of the second through hole 105 coincides with the center line of the optical structure area 201 .

[0064] The second through hole 105 corresponds to the optical structure region 201 , and the shape and area of ​​the second through hole 105 determine the shape and area of ​​the material layer 203 formed on the surface of the substrate 200 .

[0065] In this embodiment, the first through hole 104 corresponds to the target 202 , which includes: a center line of the first through hole 104 coincides with a center line of the target 202 .

[0066] The center line of the first through hole 104 coincides with the center line of the target material 202 , that is, the target material 202 is located at the center of the first through hole 104 and the second through hole 105 , so that the thickness of the subsequently formed material layer 203 can show a continuous change trend with the thickest point at the center and the thinnest at the edge.

[0067] The material of the material layer 203 includes an inorganic dielectric material, and the inorganic dielectric material includes titanium oxide, niobium oxide, silicon carbide, silicon oxide, lithium niobate, silicon nitride, tantalum oxide, hafnium oxide, and aluminum oxide.

[0068] The target 202 may be made of titanium oxide, niobium oxide, silicon carbide, silicon oxide, lithium niobate, silicon nitride, tantalum oxide, hafnium oxide, aluminum oxide, or titanium.

[0069] There is a first distance H' between the first mask plate 101 and the second mask plate 102, and the first through hole 104 has a first area S1. A material layer 203 with a continuously gradient thickness is formed on the optical structure area 201 by bombarding the target material, and also includes: adjusting the size of the first distance H' and adjusting the size of the first area S1 to adjust the thickness and thickness variation of the material layer 203 at each position on the optical structure area 201.

[0070] The specific process of adjusting the thickness of the material layer 203 at each position on the optical structure region 201 by adjusting the size of the first spacing H' and the size of the first area S1 can be found in Figure 7 and Figure 8 , Figure 7 Schematic diagram of establishing a coordinate system based on the material layer 203. Figure 8 Schematic diagram of establishing a coordinate system for each structure based on the material layer 203.

[0071] Please refer to Figure 7 , with the intersection of the central axis L3 of the material layer 203 and the substrate 200 as the coordinate origin O, an axially symmetric coordinate system (r, h) is established, where the horizontal coordinate r of the coordinate system (r, h) is the distance from any point on the top surface of the material layer 203 relative to the coordinate origin O, and the vertical coordinate h of the coordinate system (r, h) is the distance from the center of the target material 202 to the surface of the substrate 200.

[0072] The central axis L3 of the material layer 203 coincides with the center line of the optical structure region 201 .

[0073] Please refer to Figure 8 The target 202 has a radial length S, and the center line of the target 202 passes through the coordinate origin O, that is, the target 202 is symmetrically arranged with respect to the ordinate of the coordinate system in the length direction. The target 202 has a sputtering point A at any position relative to the surface of the substrate 200, and the movable coordinate range of the sputtering point A relative to the center of the target 202 is (-S / 2, S / 2); a is the radial coordinate of any sputtering point A of the target 202 relative to the center line of the target 202; M is the radial coordinate of the target 2 02 material mass; ρ is the density of the target material 202 material; h is the distance from the center of the target material 202 to the surface of the substrate 200; r is the coordinate of any point on the top surface of the material layer 203 relative to the coordinate origin O; T(r) is the thickness at any point r on the top surface of the material layer 203; H is the distance between the first mask plate 101 and the substrate 200; R1 is the first aperture of the first through hole 104, and da is the integral factor of any sputtering point A of the target material 202 in the radial direction of the target material 202.

[0074] In this embodiment, the distance H between the first mask plate 101 and the substrate 200 is H′+d2, where H′ is a first distance between the first mask plate 101 and the second mask plate 102, and d2 is a second thickness of the second mask plate 102.

[0075] In this embodiment, the distance h from the center of the target 202 to the surface of the substrate 200 is H+d1+the distance between the target and the first mask 202 , where d1 is the first thickness of the first mask 101 .

[0076] In other embodiments, the second mask plate is not in direct contact with the substrate, and the distance H between the first mask plate and the substrate is H′+d 2 + the spacing between the second mask plate and the substrate.

[0077] The size of the first area S1 is adjusted, that is, the size of the first area S1 is adjusted by adjusting the first aperture R1 of the first through hole 104 .

[0078] Adjusting the size of the first interval H', that is, adjusting the size of the vertical coordinate h by adjusting the size of the first interval H'.

[0079] The thickness of the material layer 203 gradually increases from the edge to the center of the optical structure region 201 .

[0080] Specifically, within a preset size range along the surface of the substrate 200 , the thickness of the material layer 203 continuously changes from 15 nanometers to 400 nanometers.

[0081] In this embodiment, the preset size range is 3 cm to 4 cm, or 2 cm to 3 cm, 4 cm to 5 cm, or even less than 2 cm or greater than 5 cm, etc., which are all within the scope of protection requested by the present invention. The present invention does not limit the preset size range. The specific size range can be limited according to the requirements of the optical structure during design, or the regional requirements for forming the grating structure. In this regard, what is shown in the figure is only an example, which is feasible.

[0082] Please refer to Figure 9 The material layer 203 includes an effective area A and an ineffective area. The effective area A is the area where the optical structure is subsequently formed, and the ineffective area is the area that needs to be removed. A protective layer 210 is formed on the surface of the material layer 203. The surface of the protective layer 210 is a flat surface, and the protective layer 210 exposes the surface of the ineffective area.

[0083] The protective layer 210 is used to fill the top surface of the material layer 203. The surface of the protective layer 210 is a flat surface, which provides a flat surface for the subsequent formation of a patterned mask layer, so as to form a patterned mask layer with precise size.

[0084] The material of the protection layer 210 includes photoresist.

[0085] The method for forming the protection layer 210 includes: forming an initial protection layer (not shown) on the top surface of the material layer 203 ; removing the initial protection layer on the inactive area, and forming the protection layer 210 on the active area A.

[0086] Please refer to Figure 10 , using the protective layer 210 as a mask, the ineffective area is removed, and the effective area A is retained on the substrate 200 .

[0087] Please refer to Figure 11 , a patterned mask layer 212 is formed on the protection layer 210 .

[0088] In this embodiment, the material of the patterned mask layer 212 includes photoresist.

[0089] Please refer to Figure 12 The protective layer 210 and the effective area A are etched using the patterned mask layer 212 as a mask, so that the effective area A is formed into an optical structure 211 on the optical structure area 201 of the substrate 200. The protective layer 210 is located on the optical structure 211, and the thickness of the optical structures 211 gradually increases along the edge of the optical structure area 201 toward the center.

[0090] In one embodiment, the protective layer 210 and the active area A are etched with a mask until the surface of the substrate 200 is exposed, so that the active area A is formed into an optical structure 211 on the optical structure region 201 of the substrate 200 .

[0091] In this embodiment, the process of etching the protection layer 210 and the active area A using the patterned mask layer 212 as a mask includes a dry etching process.

[0092] Please refer to Figure 13 After forming the optical structure 211, the method further includes removing the patterned mask layer 212 and the protective layer 210 to form the optical structure.

[0093] The optical structure includes: a substrate 200, wherein the substrate 200 includes one or more optical structure areas 201; optical structures 211 located on the optical structure areas 201, wherein the thickness of the optical structures 211 gradually increases along the direction from the edge of the optical structure area 201 to the center.

[0094] The thickness of the optical structure 211 gradually increases from the edge to the center of the optical structure region 201. Specifically, within a preset size range along the surface of the substrate 200, the thickness of the optical structure 211 continuously changes from 15 nanometers to 400 nanometers.

[0095] In this embodiment, the preset size range is 3 cm to 4 cm.

[0096] In this embodiment, the process of removing the patterned mask layer 212 and the protection layer 210 includes a wet etching process.

[0097] In another embodiment, after removing the patterned mask layer 212 and the protective layer 210, the method further includes thinning the substrate 200 to form the optical structure. Specifically, the substrate 200 is etched by an etching process to form an optical structure with a continuously gradient thickness on the substrate.

[0098] In other embodiments, the substrate 200 may not be thinned.

[0099] In summary, the thickness of the formed optical structure 211 gradually increases from the edge of the optical structure region 201 toward the center. Therefore, the thickness variation trend of the optical structure 211 can be precisely controlled, with some optical structures 211 exhibiting a continuous thickness variation. By designing the mask structure, the thickness variation of the material layer at different locations can be precisely controlled, thereby forming an optical structure with a continuously gradient thickness variation. This structural design, on the one hand, modulates the diffraction efficiency of the optical structure at different locations, thereby improving the display uniformity and visual quality of the optical structure at different locations. Furthermore, this structural design can also enhance the display appearance of the optical structure. The continuously gradient thickness design prevents sudden changes in thickness at different locations, thereby improving the dimensional accuracy and visual quality of the optical structure.

[0100] In another embodiment, the method for forming the optical structure includes: forming a patterned photoresist layer on the surface of the effective area of ​​the material layer 203, the patterned photoresist layer exposing the surface of the invalid area and exposing a portion of the surface of the effective area; etching the effective area and the invalid area using the patterned photoresist layer as a mask until the surface of the substrate is exposed, removing the invalid area, and forming the material layer into an optical structure.

[0101] In another embodiment, the effective area is the entire material layer, and the method for forming the optical structure includes: forming a patterned mask layer on the top surface of the entire material layer, and then etching the material layer with the patterned mask layer to form an optical structure on the substrate.

[0102] In another embodiment, in the process of etching a material layer to form an optical structure, the material layer is etched to a preset depth to form an optical structure and a plurality of grooves located within the optical structure, wherein the bottoms of the grooves are located within the material layer, the depths of the plurality of grooves are the same, and the depths of the plurality of grooves are less than any thickness of the material layer.

[0103] In the above embodiment, by adjusting the first spacing between the first mask plate and the second mask plate, and adjusting the size of the first area of ​​the first through hole, the thickness of the material layer at each position on the optical structure area is precisely adjusted, and the design of the thickness continuous gradient structure is controlled to improve the display efficiency of the optical structure at different positions and improve the display uniformity, thereby improving the display effect of the optical structure. At the same time, the display appearance of the optical structure is improved, and the dimensional accuracy and visual effect of the optical structure are enhanced.

[0104] Accordingly, further, an embodiment of the present invention further provides a diffraction optical waveguide, wherein the diffraction optical waveguide at least includes an outcoupling grating region and / or a turning grating region, wherein the grating structure in the outcoupling grating region or the turning grating region is based on Figures 3 to 13 The optical structure is prepared by the forming method.

[0105] In the above embodiments, the grating structure in the grating region is obtained by any of the above embodiments. The optical structure in the above embodiments is the grating structure, and a grating structure with a continuously gradient thickness is formed in this way.

[0106] The diffraction optical waveguide is used for diffraction imaging; and the optical structure includes a grating structure.

[0107] Of course, in some other embodiments, the diffraction optical waveguide may also include a recycling grating region, a pupil expansion grating region, etc. In this regard, the present invention does not limit the specific grating function.

[0108] The diffraction waveguide obtained by the above method is based on forming a material layer with continuously varying thickness on a substrate to form a grating structure with continuously varying depths, with different grating structures having different depths. On the one hand, this method modulates the diffraction efficiency of the prepared grating structure at different positions, resulting in a continuously varying diffraction efficiency at different positions, thereby improving the display uniformity and display efficiency of the diffraction waveguide and enhancing the display effect of the waveguide. On the other hand, the diffraction waveguide obtained by this method has different grating structures with continuously varying depths at different positions, which is different from the existing partitioned structure in terms of display appearance, thereby preventing the visual differences caused by sudden changes in thickness at different positions and achieving a better visual appearance. The present invention has unexpected technical effects and significant improvements compared to the existing technology.

[0109] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A mask plate structure for preparing a grating structure in a diffraction optical waveguide, characterized in that: include: a first mask plate, wherein the first mask plate has a first through hole penetrating the first mask plate; a second mask plate, wherein the second mask plate has a second through hole penetrating the second mask plate; The second mask plate is attached to the substrate; The first mask plate and the second mask plate are arranged in parallel with each other and have a distance therebetween. The first mask plate and the second mask plate are used to form a material layer with a continuously gradient thickness in the second through-hole region. The thickness of the material layer at different positions is adjusted by adjusting the size of the distance and the area of ​​the first through-hole. The material layer includes an effective area and an ineffective area. The grating structure in the diffraction optical waveguide is formed in the effective area. The diffraction efficiency of the grating structure at different positions is modulated so that the grating structure has a continuously gradient diffraction efficiency at different positions. The ineffective area is the area that needs to be removed.

2. The mask structure according to claim 1, wherein: The first mask plate and the second mask plate are connected via a connecting portion to form an integrated structure; or the first mask plate and the second mask plate are independently formed on a substrate, and the second mask plate is in contact with the substrate.

3. The mask structure according to claim 1 or 2, wherein: A projection range of the first through hole projected onto the second mask plate is located within the second through hole; and the first mask plate and the second mask plate are arranged in parallel.

4. The mask structure according to claim 3, wherein: A center line of the first through hole coincides with a center line of the second through hole.

5. A method for forming a grating structure in a diffraction optical waveguide, based on the mask structure according to any one of claims 1 to 4, characterized in that: include: Providing a substrate, the substrate comprising one or more optical structure regions; A mask plate structure is provided, comprising: a first mask plate and a second mask plate arranged in a direction perpendicular to a surface of a substrate; The first mask plate has a first through hole penetrating the first mask plate; The second mask plate has a second through hole penetrating the second mask plate; The first mask plate and the second mask plate are arranged in parallel with each other and have a constant distance therebetween; providing a target material, disposed above the substrate; The mask structure is arranged between the target material and the substrate, the second mask plate contacts the substrate, the second through hole corresponds to the optical structure area, and the first through hole corresponds to the target material; forming a material layer with a continuously gradient thickness on the optical structure region by bombarding the target material; The material layer includes an effective area and an ineffective area. The grating structure in the diffraction optical waveguide is formed in the effective area. The diffraction efficiency of the grating structure at different positions is modulated so that the grating structure has a continuously gradient diffraction efficiency at different positions. The ineffective area is the area that needs to be removed.

6. The method for forming a grating structure in a diffraction optical waveguide according to claim 5, wherein: The material layer includes an effective area and an ineffective area; the formation method also includes: forming a protective layer on the surface of the material layer, the surface of the protective layer is a flat surface, and the protective layer exposes the surface of the ineffective area; using the protective layer as a mask to remove the ineffective area; forming a patterned mask layer on the surface of the protective layer; etching the protective layer and the effective area using the patterned mask layer as a mask, so that the effective area is formed into an optical structure on the optical structure area of ​​the substrate, the protective layer is located on the optical structure, and the thickness of several optical structures gradually increases along the edge of the optical structure area toward the center; after the optical structure is formed, the protective layer is removed.

7. The method for forming a grating structure in a diffraction optical waveguide according to claim 5, wherein: The formation method also includes: forming a patterned mask layer on the surface of the material layer; etching the material layer using the patterned mask layer as a mask to form an optical structure on the optical structure area, and the thickness of several of the optical structures gradually increases along the edge of the optical structure area toward the center.

8. A diffraction optical waveguide, characterized in that: At least includes an outcoupling grating region and / or a turning grating region, and the grating structure in the outcoupling grating region or the turning grating region is prepared based on the method for forming a grating structure in a diffraction optical waveguide according to any one of claims 5 to 7.

Images