Method for manufacturing a master template and stamp of a diffraction grating for a diffraction optical element, master template, and stamp

Abstract

A method for manufacturing a master template (20) of a diffraction grating of a diffractive optical element. A layer (250) of material (200) is deposited on a substrate (108) of a master template (180) through perforations (204) in a plate (202), the cross-sectional area of ​​the perforations (204) being dependent on the position of the perforations (204) in the plate (202), the plate (202) and the substrate (108) being spaced apart by a non-zero distance (D). The height of the at least one layer (250) above the substrate (108) varies with the change in area of ​​the perforations (204). Convex structures (180) are formed on the substrate (108) by removing the at least one layer (250) from areas resulting in concave structures (182) between the convex structures (180). The fill factor and height of the convex structure (180) are made proportional, and at the same time, the convex and concave structures (180, 182) have a relationship with the grooves (902) and ridges (900) of the diffraction grating (904), and the relationship depends on the proportionality.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a master template (original plate) and a stamp for a diffraction grating of a diffractive optical element, a master template, and a stamp. [Background Art]

[0002] Diffractive optical element (DOE)-based optical couplers for augmented reality (AR) eyewear typically comprise nanostructures such as diffraction gratings. Modulation of the nanostructures is required to optimize the optical performance of the optical coupler. These modulations can be feature shape modulation, feature size modulation, or height modulation. All of these can be used to achieve optimal design parameters for the optical coupler.

[0003] In a replication process, the goal is to copy the DOE pattern on a master template to another wafer. Replication can be performed on a permanent layer that will later function as an optical element. In the first case, the modulated nanostructures of the master template are directly transferred to the permanent layer. If modulations such as shape, feature size, and height modulations are required, they need to be present in the master template.

[0004] When a pattern is transferred from an initially patterned sacrificial layer to a permanent layer(s) deposited on the wafer, the height modulation of the final layer can be performed during the deposition phase. The sacrificial layer is deposited, for example, by spin coating, resulting in a uniform film thickness across the wafer. However, if modulation of the shape or size of features is required, the different volumes required by different feature sizes must be taken into account in order to fully fill the structure. This results in variations in the thickness of the unstructured layer beneath the actual structure. This makes the pattern transfer process significantly more difficult, or in some cases, impossible. To compensate for the different volume requirements of different feature sizes, there are two options: i) add a local reservoir to the master pattern to consume the extra volume of sacrificial material; ii) modulate the heights of different feature sizes within the master to compensate for the volume differences. The latter is preferred because the former can negatively impact the performance of the optical coupler. However, choosing this latter option significantly complicates the manufacturing of the master template, requiring multiple repetitions of the lithography and etching processes, which can negatively impact the mastering process yield, as each additional process step will result in a yield of less than 100%. Furthermore, each additional process step increases the risk of contamination and unwanted particles, degrading the overall quality of the master.

[0005] Therefore, improvements are eagerly awaited. [Overview of the project] [Problems that the invention aims to solve]

[0006] The present invention aims to provide improvements related to master templates and stamps used in the manufacturing process of nanostructures of the DOE. [Means for solving the problem]

[0007] The present invention is defined by the independent claims. Embodiments are defined by the dependent claims.

[0008] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings, merely as examples. [Brief explanation of the drawing]

[0009] [Figure 1A] Here is an example of AR eyewear. [Figure 1B] Here is an example of AR eyewear. [Figure 2] An example of a conventional press process is shown. [Figure 3] An example of a deposition process is shown. [Figure 4A] An example of a plate with perforations is shown. [Figure 4B] This shows an example of a layer of solid material deposited on a substrate through a perforated plate. [Figure 4C] An example of a layered patterned resist or etching mask is shown. [Figure 5] An example of the distribution of convex structures on a substrate is shown. [Figure 6] An example of a master template or stamp having a fill factor and a convex structure height that are directly proportional to each other is shown. [Figure 7] An example of a master template with a fill factor and a convex structure height that are inversely proportional to each other is shown. [Figure 8] This shows an example flowchart of a method for manufacturing a diffraction grating stamp for augmented reality eyewear. [Figure 9A] This shows an example of a manufacturing process in which a stamp is pressed onto the polymer of an optical component preform. [Figure 9B] An example of a polymer layer on a hard mask of an optical component preform after the residual layer has been removed is shown. [Figure 9C] An example of grading with a hard mask is shown. [Figure 9D] An example of grading after removing the hard mask is shown. [Figure 10]This shows an example of a flowchart for a manufacturing method of optical components. [Modes for carrying out the invention]

[0010] The following embodiments are merely examples. While the specification may refer to "one" embodiment in multiple places, this does not necessarily mean that each such reference refers to the same embodiment(s) or that its configuration applies only to a single embodiment. Combining single configurations from different embodiments may provide other embodiments. Furthermore, the terms "equip" and "include" should be understood not to limit the described embodiments to only the configurations described; such embodiments may also include configurations / structures not specifically described. All combinations of embodiments are considered possible, provided that they do not result in structural or logical inconsistencies.

[0011] It should be noted that while the figures illustrate various embodiments, they are simplified diagrams showing only some structural and / or functional entities. Connections shown in the figures may refer to logical or physical connections. It will be apparent to those skilled in the art that the described apparatus may also have other functions and structures not described in the figures and text. Details of some functions, structures, and signal transmissions used for measurement and / or control should be understood as irrelevant to the actual invention; therefore, they do not need to be described in detail here.

[0012] This specification proposes concepts of height-modulated master templates, stamps based on master templates, and methods for manufacturing them. The master template refers to an imprint master template. The surface of the master template has a fine pattern corresponding to the pattern of a diffraction grating. The stamp also has a fine pattern on its surface for manufacturing a diffractive optical element, for example, by an imprint method (see Figures 9A-9D). The fine pattern of the stamp corresponds to the fine patterns of the diffraction grating and the master template, and the fine pattern of the stamp has an inverted tone relative to the fine pattern of the master template, and vice versa. Diffractive optical elements can have various applications. In one embodiment, the master template is manufactured first, and then a stamp is replicated based on the master template. In another embodiment, the stamp is manufactured directly without using a master template. This method allows for the deposition of a custom, predefined thickness profile that defines the height modulation map of the master template and stamp structures.

[0013] In this specification, a master template refers to a template that serves as the prototype for a stamp, and stamps are manufactured based on this master template. Therefore, a master template may be manufactured first, followed by stamps. Stamps are used in the manufacturing process of diffraction gratings for optical elements. However, a master template can also be used in the manufacturing process of diffraction gratings for optical elements. Therefore, in such cases, a master template can also be considered a stamp.

[0014] A method for manufacturing a master plate comprises two main steps: i) deposition of a pre-designed height map using a plate 202 that may be referred to as a shadow mask, and ii) patterning of said layer resulting in a controllable in-plane pattern with a predefined height. Deposition of a height gradient is performed by a specially perforated pattern, wherein the ratio between mask openings (i.e., perforations 204) and solid mask material can vary along the X direction and / or Y direction, and is further performed by a special holder (i.e., a spacer structure 206 that provides a specific distance between the plate 202 and the substrate 108) (see FIG. 3).

[0015] FIG. 1A and FIG. 1B show an example of AR (augmented reality) eyewear to which a diffractive optical element can be applied. However, the diffractive optical element can more generally be used in any screen where the environment can also be viewed in addition to the information transmitted by the diffraction grating(s). In general, diffractive optical elements can also be applied outside of AR applications where light or images are coupled into and / or out of waveguides / light guides. Diffractive optical elements are applicable to AR, virtual reality (VR), and / or mixed reality (MR) applications. Diffractive optical elements can also be applied to domestic, leisure, and / or industrial AR, VR, or MR. Such examples include screens of computers, tablets, and / or portable electronic devices, and screens / windshields of land vehicles (passenger cars, buses, lorries, trucks, etc.), aircraft (airplanes, helicopters, gliders, airships, etc.), and / or watercraft (boats, ships, submarines, etc.).

[0016] The eyewear may look like, for example, glasses, spectacles, or goggles. In one embodiment, the eyewear may be connected to headwear such as, for example, a cap, a hat, a helmet, or spectacles. Although FIGS. 1A and 1B show AR eyewear for both eyes of a user, the AR eyewear may have a structure that can be used for only one eye.

[0017] In FIG. 1A, the eyewear comprises an optical element 10 having at least one diffraction grating 100, 102, 104, and an image generation unit 12, which may in turn have an image source 14 and an optical component arrangement 16. The optical element 10 can be an example of a diffractive optical element that can be fabricated using a stamp. The image generation unit 12 generates visible light of an image (a still image or a moving image), and this visible light is coupled into a visible light waveguide 106 via the optical component arrangement 16 and the diffraction grating 102 on the surface of the waveguide 106. In FIG. 1B, the waveguide 106 comprises two portions A and B, each corresponding to one eye 150, 152. The image generation unit 12 can direct the visible light of the image to the optical component arrangement 16, which can split the light into the two portions A and B. Instead of optical splitting, the eyewear may have two image generation units 12, each corresponding to one portion A and B.

[0018] In one embodiment, the diffraction gratings 100 to 104 may be provided on either surface of the waveguide 106. In one embodiment, at least one of the diffraction gratings 100 to 104 may be located on a surface of the waveguide 106 opposite to at least another one of the diffraction gratings 100 to 104.

[0019] FIG. 2 illustrates an example of a problem related to the prior art, in addition to the problems described in the background section of the present specification. The stamp has convex structures 180 and concave structures 182, the height of the convex structures 180 is constant, but the fill factor varies in this example. All concave structures 182 are at substantially the same height. That is, the features of the stamp are thicker at the convex structures 180 than at the concave structures 182. The local fill factor F of the stamp can be determined as the ratio of the feature width lw to the period d, F = lw / d. The term fill factor is useful and well-known, as those skilled in the art use the corresponding term when referring to diffraction gratings.

[0020] Figure 2 can also be used to illustrate what a stamp is and what it is used for. The surface profile of the stamp is replicated on a polymer such as resin 184 by forming a pattern that is toned inverted compared to the stamp. The replication process can be thought of as an inverted replication process, which may be an imprint process in which the tones are reversed.

[0021] The resin can be on the hard mask 190, which in turn is on the diffraction grating material 192. Finally, the diffraction grating material 192 is on the optical guide 194. The height H of the residual layer 186 of the polymer 184 is not constant but varies. The inversion process causes the polymer 184 to have a concave structure between the convex structure 180 of the stamp. 182 The process may also involve an imprinting process in which a stamp is pressed onto the polymer 184 so that it flows into the stamp. Once the stamp is separated from the polymer 184, the polymer 184 has a surface profile that is similar to, but not at all, the inverted surface profile of the stamp. That is, changes in the height H of the residual layer 186 are caused by changes in the volume occupied by the polymer 184 inside the concave structure 182 of the stamp. Variations in the thickness of the unstructured layer (i.e., the residual layer 186) make the pattern transfer process significantly difficult, or perhaps completely impossible. The hard mask 190 may include, for example, chromium (Cr) or chromium oxide (Cr2O3).

[0022] Figure 3 shows an example of a deposition process, which can be used to form a surface profile of the master template 20 or stamp 22 in order to mitigate or eliminate variations in the thickness of the unstructured layer (i.e., the residual layer 186 during the inversion replication process).

[0023] Material 200 is deposited on the substrate 108 as layer 250 through perforations 204 in plate 202. The surface profile of the master template 20 (i.e., the surface profile of layer 250) can be used directly or indirectly to form at least one diffraction grating 100, 102, 104 of the eyewear after deposition. Plate 202 is set at a non-zero distance D from the substrate 108. The distance D can be set, for example, using a spacer structure 206. Plate 202 can be supported by the spacer structure 206. If the shape of the substrate 108 is circular, the spacer structure 206 may be a ring around the outer contour of the substrate 108.

[0024] In one embodiment, a non-zero distance D between the plate 202 and the substrate 108 can be set.

[0025] The overall thickness of the structure including the spacer structure 206 may be greater than the distance D. The spacer structure 206 may have a circular outer perimeter and an interior with a circular opening, a rectangular opening(s), and / or other custom-shaped openings that assist in positioning the plate 202 above the substrate 108 and prevent material 200 from accumulating in other areas. Thus, the spacer structure 206 may have a thickness equal to the distance D. The material of the spacer structure 206 may include, for example, metal, glass, ceramics, etc. In one embodiment, the spacer structure 206 may include, for example, anodized aluminum. In one embodiment, the spacer structure 206 may include at least one adjustment device 210. The adjustment device 210 may be, for example, mechanical, electromechanical, hydraulic, and / or pneumatic. A mechanical adjustment device may include, for example, a screw. An electromechanical adjustment device may include, for example, an electric motor and a screw rotated by the electric motor.

[0026] Distance D is a parameter that can be considered depending on the following: a) the type of deposition reactor, the nature and parameters of the deposition process, b) the thickness of plate 202, c) the height and / or width of the perforations 204 within plate 202, and the feature size including the structure of the perforations 204. Distance D may also depend on d) the specific DOE layout used directly or indirectly by the master template 20 for replication, and e) the configuration of the DOEs on the substrate 108 used directly or indirectly by the master template 20 for replication. Here, DOE layout means that different diffraction grating shapes are possible and depend on a specific shape (e.g., rectangular, bowtie, triangular, etc.), which may require different configurations of the perforations 204 within plate 202. DOE configuration means that there are various options depending on how several DOEs with varying heights are arranged relative to each other, for example, to adjust or control the height profile of layer 250. The DOE layout, the master template 20 layout, and the stamp 22 layout are interdependent and have a deterministic relationship.

[0027] The distance D between the plate 202 and the substrate 108 can be set to a specific optimal value. In one embodiment, the distance D can be, for example, about 5 mm. If the distance D is too small, the features of the perforations 204 may not be sufficiently uniform, and the structure of the layer 250 may not be sufficiently conformal. If the distance D is too large, the accuracy of local film thickness control may decrease. In one embodiment, the plate 202 may be tilted relative to the substrate 108.

[0028] In one embodiment, the distance D between the plate 202 and the substrate 108 may depend on the area of ​​the perforations 204 in the plate 202. In one embodiment, the distance D between the plate 202 and the substrate 108 may depend on the minimum area of ​​the perforations 204 in the plate 202.

[0029] In one embodiment, the distance D may decrease as the area of ​​the perforations 204 in the plate 202 decreases. In one embodiment, the distance D may decrease as the average area, maximum area, and / or minimum area of ​​the perforations 204 in the plate 202 decreases. Accordingly, the distance D may increase as the area of ​​the perforations 204 in the plate 202 increases. In this way, the material 200 can spread to areas of the substrate 108 that do not directly overlap or face the perforations 204. Such spreading then yields a layer 250 of the material 200 that is at least substantially uniform, or at least fairly / moderately flat, on the substrate 108.

[0030] In one embodiment, the spacer structure 206 may also include additional elements that are specific to the case and are not shown. These elements may be a) additional configurations supporting the plate 202, or b) additional configurations used to shield areas of the substrate 208, i.e., areas corresponding to the manufactured DOE (or surrounding the DOE) where material should not be deposited.

[0031] The material of plate 202 can include, for example, metal, glass, or ceramics. In one embodiment, the metal can be, for example, high-purity stainless steel. In one embodiment, the thickness of plate 202 can be, for example, about 0.001 mm to about 1 mm. In one embodiment, a typical thickness can be, for example, about 0.01 mm to about 0.1 mm. In one example, the thickness can be about 0.05 mm.

[0032] In one embodiment, the diameters of the substrate 108 and plate 202 can vary, for example, from several tens of millimeters to 450 mm. In one embodiment, the diameters of the substrate 108 and plate 202 can be, for example, about 100 mm. The deposition system 208 can be scaled / modified to accommodate substrates 108 with smaller / larger diameters, or it can be made scalable.

[0033] As shown in an example in Figure 4A, the area of ​​the perforation 204 changes in a predetermined manner depending on its position within the plate 202 (only a few perforations are labeled in Figure 4A because it is not possible to number all of them). The area of ​​the perforation 204 refers to the cross-sectional area, whose normal is parallel to the longitudinal axis of the perforation passing through the plate 202 and parallel to the normal of the surface of the plate 202. In the example in Figure 4A, the area of ​​the perforation 204 changes in the X-axis direction but remains constant in the Y-axis direction. In one embodiment, the area of ​​the perforation 204 may change in both the X and Y directions. In one embodiment, the area of ​​the perforation 204 may change in either the X or Y direction only. The dimensions, each of which can be considered a spatial range orthogonal to and / or independent of another dimension, can be those of the Cartesian coordinate system or the polar coordinate system.

[0034] Figure 4A shows an example of perforation and modulation of the area of ​​perforation 204 in the X direction. The shape of perforation 204 can be, for example, hexagonal, circular, rectangular, linear, star-shaped, or any combination thereof. The shape of perforation 204 can also be custom-made.

[0035] The plate 202 having perforations 204 can be fabricated to satisfy a desired opening-to-internal real area ratio or fill factor in the X direction, X direction and Y direction.

[0036] In one embodiment, the solid material 200 can be converted into a fluid state, which can be in a gaseous or vaporous state, in order to pass through the perforations 204 of the plate 202. The fluid material 200 then solidifies on the substrate 108 as a layer 250.

[0037] In one embodiment, the transfer of the material for deposition on the substrate 108 can be carried out, for example, in an evaporated state. Subsequently, the solid material 200 may be in a vapor state, and in a vapor deposition process, for example, the vapor is condensed on the substrate 108 as a layer 250 that can form a film structure. Vapor deposition can be achieved using, for example, sputtering, chemical vapor deposition, physical vapor deposition, etc., but is not limited to these.

[0038] Those skilled in the art are familiar with a variety of deposition systems and processes that can be used as the deposition system 208. The solid material 200 can be freely selected. Examples of the solid material 200 may be, but are not limited to, silicon, silicon dioxide, silicon nitride, or aluminum. For example, the substrate 108 may be covered with a hard mask 190 or an etch-stop layer, the purpose of which is to stop the etching process of layer 250 of the solid material 200 at the surface of the hard mask 190 when layer 250 of the solid material 200 is etched to the concave structure 182, thereby protecting the substrate 108 from etching (see Figures 4B, 4C, and 5).

[0039] Figure 4B shows an example of how the perforation pattern of plate 202 can be translated into a specific height profile of the layer 250 of material 200 on substrate 108. The distribution of material 200 within layer 250 may be linear, as in this example, or it may follow any shape, such as a nonlinear function, depending on the size distribution of the perforations 204 in plate 202.

[0040] The unit cells of features within plate 202 must be small enough to provide a high degree of local thickness control and good uniformity of layer 250. Since the minimum feature size is limited by several factors, including the thickness of plate 202 and the perforation technique, thin masks, such as 0.1 mm or less, may generally be preferred. The required resolution of the features on plate 202 and the thickness of plate 202 depend on the specific layout of the master template 20, stamp 22, and / or the manufactured DOE.

[0041] Figure 4C shows an example of a patterned resist or etching mask layer 302 on a layer 250 of material 200. The layer 250 of material 200 can then be etched to form features including a convex structure 180 and a concave structure 182 (see also Figures 5, 6, and 7). In one embodiment, the etching may include dry etching. Alternatively, features on the master template 20 or stamp 22 may be formed, for example, by laser ablation or other suitable prior art patterning method.

[0042] As shown in an example in Figure 5, the convex and concave structures 180 and 182 of the master template 20 or stamp 22 are thus made of layers 250 of solid material 200, and their fill factors and heights follow the fill factors and heights of the etching mask layer 302. As described above, a material removal device, which may include an etching device or other suitable prior art material removal device, can remove the solid material 200 of layer 250 from the position of the concave structure 182 and retain the solid material 200 of layer 250 in the position of the convex structure 180. The horizontal axis X indicates position in one direction, and the vertical axis indicates height H. Both axes are of arbitrary scale.

[0043] Figure 6 shows an example of a master template 20 produced by the process shown in Figures 3 to 5. This master template 20 may be used as a stamp 22, or the master template 20 may be duplicated to produce a stamp 22. Using the inversion duplication process, the master template 20 needs to be copied an even number of times to obtain a master template 20 or stamp 22 in which the fill factor and height of the convex structure 180 are directly proportional to each other.

[0044] In one embodiment, two different fill factors may not necessarily have different heights of the convex structure 180, and vice versa. However, there may be at least two different fill factor ranges having different heights of the convex structure 180, while at least one of the fill factor ranges has only one height of the convex structure 180. Thus, there may be a single fill factor range where the height of the convex structure 180 is constant, but the different fill factor ranges have different heights of the convex structure 180. Here, any fill factor range is part of the full scale of fill factors of the master, stamp, and / or diffraction grating.

[0045] Figure 7 shows an example of a master template 20 produced by the process shown in Figures 3 to 5. This master template 20 does not have to be used as a stamp 22; the master template 20 may be duplicated to produce the stamp 22. Using the inversion duplication process, an odd number of copies of the master template 20 are required to obtain a stamp 22 in which the fill factor and height of the convex structure 180 are directly proportional to each other.

[0046] The master template 20 for manufacturing a diffractive optical element has a fill factor and height of the convex structure 180 of the master template 20 that are proportional to each other, and the convex and concave structures 180 and 182 have a predetermined relationship with the grooves 902 and raised portions 900 of the diffraction grating 904.

[0047] The fact that the fill factor and height of the convex structure 180 of the master template 20 are proportional means that the fill factor and height of the convex structure 180 may be directly proportional to each other or inversely proportional to each other, and that they are proportional in a predetermined manner in order to modulate the height of the convex structure 180 to compensate for volume differences and to mitigate or eliminate changes in the thickness of the unstructured layer (i.e., residual layer 186) during the inversion replication process.

[0048] If the fill factor and height of the convex structure 180 of the master template 20 are directly proportional to each other, then as the value of the fill factor increases, the value of the height of the convex structure 180 increases, and vice versa. If the fill factor and height of the convex structure 180 of the master template 20 are directly proportional to each other, then as the value of the height of the convex structure 180 increases, the fill factor also increases, and vice versa.

[0049] If the fill factor and height of the convex structure 180 of the master template 20 are inversely proportional to each other, then as the value of the fill factor increases, the value of the height of the convex structure 180 decreases, and vice versa. If the fill factor and height of the convex structure 180 of the master template 20 are directly proportional to each other, then as the value of the height of the convex structure 180 decreases, the value of the fill factor increases, and vice versa. Those skilled in the art are familiar with the concept of proportionality. That is, the fill factor and height of the convex structure 180 may, for example, have the same ratio, and / or the change in fill factor and the change in height of the convex structure 180 may be similar or opposite. The same ratio may be a constant ratio, the ratio may remain within a predetermined range, or the ratio may behave in a predetermined way to modulate the height of the convex structure 180 to compensate for volume differences. This proportionality also mitigates or eliminates variations in the thickness of the unstructured layer (i.e., residual layer 186) during the inversion replication process.

[0050] In one embodiment, the master template 20 has a fill factor and height of the convex structure 180 of the master plate 20 that are directly proportional to each other, the convex structure 180 is configured to produce grooves 902 of the diffraction grating 904, and the concave structure 182 is configured to produce raised portions 900 of the diffraction grating 904.

[0051] In one embodiment, the master template 20 has a fill factor and height of the convex structure 180 of the master plate 20 that are inversely proportional to each other, the convex structure 180 is configured to produce raised portions 900 of the diffraction grating 904, and the concave structure 182 is configured to produce groove portions 900 of the diffraction grating 904.

[0052] The stamp 22 for manufacturing a diffractive optical element similarly has a fill factor and height of the convex structure 180 of the stamp 22 that are directly proportional to each other, and the convex and concave structures 180, 182 have a predetermined relationship with the grooves 902 and the raised portion 900 of the diffraction grating 904 such that the convex structure 180 is configured to produce the grooves 902 of the diffraction grating 904 and the concave structure 182 is configured to produce the raised portion 900 of the diffraction grating 904.

[0053] Figure 8 shows a method for manufacturing a diffraction grating stamp 22 for augmented reality eyewear. In step 800, at least one layer 250 of material 200 is deposited on the substrate 108 of the master template 20 through perforations 204 of the plate 202, the area of ​​the perforations 204 depends on the position of the perforations 204 within the plate 202, and the plate 202 and the substrate 108 are spaced apart from each other by a non-zero distance D.

[0054] In step 802, the height of at least one layer 250 on the substrate 106 is changed in accordance with the change in the area of ​​the perforation 204.

[0055] In step 804, a convex structure 180 is formed on the substrate 108 by removing at least one layer 250 from the region, resulting in concave structures 182 between the convex structures 180.

[0056] In step 806, the fill factor and height of the convex structure 180 are made proportional to each other, but the convex and concave structures 180 and 182 have a relationship with the grooves 902 and raised portions 900 of the diffraction grating 904, and this relationship depends on proportionality.

[0057] In one embodiment, the fill factor and height of the convex structure 180 are made to be proportional to each other in a predetermined manner. The convex and concave structures 180 and 182 then have a correspondingly determined relationship with the grooves 902 and raised portions 900 of the diffraction grating 904. The raised portions 900 and grooves 902 can be determined such that the thickness of the grading 904 is thinner in the grooves 902 and thicker in the raised portions 900 than in the grooves 904.

[0058] If the fill factor and height of the convex structure 180 of the master template 20 or stamp 22 formed in this way are inversely proportional to each other, steps 800-806 can substantially directly produce the master template 20 or stamp 22. If the fill factor and height of the convex structure 180 are directly proportional to each other, steps 800-806 can directly produce the master template 20 that needs to be inverted and duplicated.

[0059] Therefore, in order to form the stamp 22, either of the following steps 808 and 810 may or must be performed.

[0060] In step 808, in response to the inverse relationship between the fill factor and height of the convex structure 180, the master template 20 is duplicated M times (where M is an odd number) based on the inversion replication process. The inversion replication process inverts the profile of the master template 20 such that the convex structure 180 of the master template 20 becomes the concave structure 182 of the replica, and the concave structure 182 of the master template 20 becomes the convex structure 180 of the replica.

[0061] In step 810, in response to the fill factor and height of the convex structure 180 being directly proportional to each other, the stamp 22 is formed from the master template 20 without a replication process, or in response to the fill factor and height of the convex structure 180 being directly proportional to each other, the master template 20 is replicated N times (N is an even number) based on an inverted replication process.

[0062] In one embodiment, the fill factor and height of the convex structure 180 can be made to be directly proportional to each other. Then, the convex structure 180 and the concave structure 182 can be made to correspond to the groove portion 902 and the raised portion 900 of the diffraction grating 904, respectively.

[0063] In one embodiment, the fill factor and height of the convex structure 180 can be made inversely proportional to each other. Then, the convex and concave structures 180 and 182 can be made to correspond to the raised portion 900 and the groove portion 902 of the diffraction grating 904, respectively.

[0064] In one embodiment, the convex-concave structure 180 can be copied in a reversed manner in order to reverse the fill factor. The height profile can also be reversed. The reversed copies of the convex-concave structures 180 and 182 are configured to correspond to the distribution and size of the grooves 902 and raised portions 900 of the diffraction grating 904.

[0065] In one embodiment, a copy of the master template 20 can be formed by pressing the convex and concave structures 180 and 182 of the master template 20 against a polymer 184, thereby copying the convex and concave structures 180 in an inverted manner. The copy of the master template 20, which includes a polymer 184 having a surface profile inverted with respect to the master template 20, can then include the inverted copies of the convex and concave structures 180 and 182 of the master template 20. The copy of the master template 20 may be a new master template 20 or a stamp 22.

[0066] In one embodiment, the deposition of layer 250 is carried out by at least one of sputtering, chemical vapor deposition, and physical vapor deposition.

[0067] In one embodiment, the convex structure 180 is formed on the substrate 108 by removing a layer 250 of solid material 200 from the substrate 108 at a position corresponding to the position of the raised portion 900 of the diffraction grating 904.

[0068] In one embodiment, the height of the layer 250 is varied in two dimensions based on the change in the area of ​​the two-dimensional perforation 204.

[0069] Figure 9A shows an example of the manufacturing steps in which a stamp 22 is pressed onto the polymer 184 of the preform 188 of a diffractive optical element. The diffraction grating layer 192 is on the optical guide 194. A hard mask 190, which can be made of, for example, chromium, is on the diffraction grating layer 192, and the polymer layer 184 is on the hard mask 190. Layers 184, 190, 192, and 194 form the preform 188 of the diffractive optical element.

[0070] The hard mask 190 is an etching mask that is harder than a soft mask such as a polymer mask. The material of the hard mask 190 can be, for example, chromium. The hard mask 190 prevents the removal process of the residual layer 186 from proceeding to the grading layer 192 and damaging it.

[0071] A stamp 22 having a fill factor and height of a convex structure 180 that are directly proportional to each other is pressed onto the polymer layer 184 to make the fill factor and height of the convex structure 180' of the polymer 184 inversely proportional to each other. The stamp 22 may be a copy of the master template 20 or may be the master template 20 itself. Since the polymer 184 can be distributed according to the stamp 22, the height H of the residual layer 186 is approximately constant.

[0072] Figure 9B shows an example in which the residual layer 186 is removed from between the convex structures 180'. In one embodiment, the removal of the residual layer 186 may be carried out by etching. Etching may include, for example, reactive ion etching (RIE).

[0073] Figure 9C shows an example in which a raised portion 900 is formed on the diffraction grating layer 192 by removing the hard mask 190 between the convex structures 180' of the polymer 184, and thus the raised portion 900 remains in the position of the convex structures 180'. In Figure 9C, the hard mask 190 is still shown to be at the top of the raised portion 900, but the polymer 184 has already been removed. In one embodiment, the raised portion 900 on the diffraction grating layer 192 can be carried out by etching. In one embodiment, the diffraction grating layer 192 may have a change in height, the height of which is a function of position, as in the case of layer 250 (see Figures 4B-5).

[0074] Figure 9D shows an example where the hard mask 190 has been removed from the top of the raised portion 900 of the diffraction grating, and the final shape of the diffraction gratings 100, 102, and 104 of the diffractive optical element (indicated by reference numeral 10 in this example) is approaching or has already reached its final shape. The hard mask can be removed using one or more suitable acids known to those skilled in the art. Additionally or alternatively, wet etching may be used. Further additional or alternatively, the hard mask may be dry-etched, for example.

[0075] Figure 10 shows an example of a manufacturing method for the optical diffraction grating elements 100, 102, and 104 of augmented reality eyewear.

[0076] In step 1000, the fill factor and height of the convex structure 180' are molded onto the polymer 184 on the hard mask 190 of the preform 188 of the diffractive optical element using a stamp 22 in which the fill factor and height of the convex structure 180' are directly proportional to each other, and the fill factor and height of the convex structure 180' of the preform 188 are inversely proportional to the fill factor and height of the stamp 22.

[0077] In step 1002, the residual layer 186 is removed from between the convex structures 180'.

[0078] In step 1004, a raised portion 900 is fabricated on the diffraction grating layer 192 on the optical guide 194 of the preform 188, and the raised portion 900 corresponds to the position of the concave structure 182 of the stamp 22. [vt 10]

[0079] In an optional step 1006, the stamp 22 can control the height of the residual layer 186 of the polymer 184. In one embodiment, the stamp 22 can cause the residual layer 186 of the polymer 184 to have a substantially constant height based on the fill factor of the stamp 22 and the height of the convex structure 180 of the stamp 22, which are directly proportional to each other. In one embodiment, the stamp 22 can change the residual layer 186 of the polymer 184 in a predetermined manner, the change depending on proportionality.

[0080] In this way, the convex structure 180 of the stamp 22 displaces a volume of polymer 184 at the position below the convex structure 180. The displaced volume of polymer 184 is related to the size of the convex structure 180. The displaced polymer 184 moves laterally / flows to the position below the concave structure 182 of the stamp 22, and the position below the concave structure 182 becomes a residual layer 186 of polymer 184. Thus, the position below the concave structure 182 can be filled in a desired manner such that the residual layer 186 has a constant height or its height follows a predetermined change.

[0081] The realization of such controllable thickness modulation in the structured master template 20 and stamp 22 enables at least two advantages in the replication of diffractive optical elements (DOEs) used, for example, as optical couplers in augmented reality (AR) eyewear. The advantages are: i) Height modulation is necessary to compensate for the volume differences required for different feature sizes in the replicated structure; ii) Height modulation can be used directly to transfer the height modulation pattern to the replicated sample.

[0082] The first advantage relates to the reliability and simplicity of the mastering and duplication process, while the latter advantage can be used to improve the performance of height-modulated DOEs.

[0083] With advances in technology, it will be apparent to those skilled in the art that the concept of the present invention can be realized in various ways. The present invention and its embodiments are not limited to the exemplary embodiments described above and can be modified within the scope of the claims.

Claims

1. A method for manufacturing a master template (20) of a diffraction grating for a diffraction optical element, Step (800) of depositing at least one layer (250) of material (200) onto the hard mask (190) of the substrate (108) of the master template (20) through perforations (204) of a plate (202), wherein the cross-sectional area of ​​the perforations (204) depends on the position of the perforations (204) within the plate (202), and the plate (202) and the substrate (108) are separated by a non-zero distance (D), The steps include: (802) changing the height of at least one layer (250) on the substrate (108) in accordance with the change in the cross-sectional area of ​​the perforation (204); Step (804) of forming a convex structure (180) on the substrate (108) by removing at least one layer (250) from a region, thereby resulting in concave structures (182) between the convex structures (180), the hard mask (190) protecting the substrate (108) and preventing the removal of the residual layer (186) from progressing to the diffraction grating layer (192) of the substrate (108) when the at least one layer (250) is removed to form the concave structures (182), A step (806) in which the fill factor and height of the convex structure (180) are made proportional, wherein the convex structure and concave structure (180, 182) are related to the groove portion (902) and raised portion (900) of the diffraction grating (904), and the relationship depends on proportionality, and the proportionality step (806) and A manufacturing method characterized by the following.

2. The fill factor and height of the convex structure are made directly proportional, The convex structure (180) and the concave structure (182) correspond to the groove portion (902) and the raised portion (900) of the diffraction grating (904), respectively. The manufacturing method according to claim 1, characterized by the above.

3. The fill factor and height of the convex structure are made inversely proportional, The convex and concave structures (180, 182) correspond to the raised portion (900) and groove portion (902) of the diffraction grating (904), respectively. The manufacturing method according to claim 1, characterized by the above.

4. The convex and concave structures (180, 182) are inverted and copied in order to reverse the height profile and fill factor, The inverted copies of the convex and concave structures (180, 182) are configured to correspond to the distribution and size of the grooves (902) and raised portions (900) of the diffraction grating (904). A manufacturing method according to claim 2 or 3, characterized by the above.

5. By pressing the convex and concave structures (180, 182) of the master template (20) against the polymer (184), a copy of the master template is formed by inverting and copying the convex and concave structures (180, 182). To make a copy of the master template (20) that includes the inverted copies of the convex and concave structures (180, 182) and The manufacturing method according to claim 4, characterized by the above.

6. The manufacturing method according to claim 1, characterized in that the deposition of the layer (250) is carried out by at least one of sputtering, chemical vapor deposition, and physical vapor deposition.

7. The manufacturing method according to claim 1, characterized in that the convex structure (180) is formed on the substrate (108) by removing the solid material (200) of the layer (250) from the substrate (108) at a position corresponding to the position of the raised portion (900) of the diffraction grating (904) (804).

8. The manufacturing method according to claim 1, characterized in that the height of the layer (250) is changed in two dimensions based on the corresponding change in the cross-sectional area of ​​the perforation (204) in two dimensions.

9. A method for manufacturing a stamp (22) of a diffraction grating for a diffraction optical element by creating a master template (20), Step (800) of depositing at least one layer (250) of material (200) onto the hard mask (190) of the substrate (108) of the master template (20) through perforations (204) of a plate (202), wherein the cross-sectional area of ​​the perforations (204) depends on the position of the perforations (204) within the plate (202), and the plate (202) and the substrate (108) are separated by a non-zero distance (D), Step (802) of changing the height of the at least one layer (250) on the substrate (108) in accordance with the change in the cross-sectional area of ​​the perforation (204), Step (804) of forming a convex structure (180) on the substrate (108) by removing the at least one layer (250) from the region, thereby creating concave structures (182) between the convex structures (180), the hard mask (190) protecting the substrate (108) and preventing the removal of the residual layer (186) from progressing to the diffraction grating layer (192) of the substrate (108) when the at least one layer (250) is removed to form the concave structures (182), A step (806) to make the fill factor and height of the convex structure (180) proportional, wherein the convex structure and concave structure (180, 182) have a relationship with the groove (902) and raised portion (900) of the diffraction grating (904), and the relationship depends on a proportional relationship, and the proportionality step (806), With respect to the aforementioned stamp (22): In response to the inversely proportional fill factor and height of the convex structure (180), the steps include: (808) duplicating the master template (20) M times (where M is an odd number) based on a profile inversion process, or Step (810) of forming the stamp (22) from the master template (20) by, without performing a replication process, or by replicating the master template (20) N times (N is an even number) based on a profile inversion process, in response to the fill factor and height of the convex structure (180) which are directly proportional. A method characterized by the following.

10. A method for manufacturing a diffractive optical element, Step (1000) of forming a convex structure (180') on a polymer (184) on a hard mask (190) of a preform (188) of a diffractive optical element, wherein the fill factor and height of the convex structure (180') of the preform (188) are the inverse of the fill factor and height of the convex structure (180) of the stamp (22), the forming step (1000), (1002) the step of removing the residual layer (186) from between the convex structures (180'), Step (1004) of creating a raised portion (900) on the diffraction grating layer (192) on the optical guide (194) of the preform (188), wherein the raised portion (900) is located at a position corresponding to the position of the concave structure (182) of the stamp (22) and A manufacturing method characterized by the following.

11. The manufacturing method according to claim 10, characterized in that the residual layer (186) of the polymer (184) has a certain height (1006) based on the fill factor by the stamp (22) and the height of the convex structure (180), which are in direct proportion.

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