Formation of angled gratings

Abstract

Systems and methods discussed herein can be used to form gratings at various tilt angles across a grating material on a single substrate by determining an ion beam angle and changing the angle of the ion beam between a plurality of ion beam angles, thereby forming a plurality of gratings having varying angle and cross-sectional geometry. The substrate is rotatable about a central axis and is capable of regulating one or more process parameters, such as the duty cycle of an ion beam, to form a grating with a depth gradient.

Description

[0001] This application is a divisional application of the invention patent application filed on October 18, 2019, with application number 201980073367.7 and invention title "Formation of an Angled Grating". Technical Field

[0002] Embodiments of this disclosure generally relate to angled etching tools. More specifically, the embodiments described herein are provided for using angled etching tools to form gratings with different tilt angles, depth gradients, and wedge angles. Background Technology

[0003] Augmented reality (AR) creates an experience for users that allows them to view their surroundings through the display lenses of AR glasses or other HMD devices. AR devices enable users to see images of virtual objects generated for display and appearing as part of the environment. AR can include sound and tactile input, as well as virtual images, graphics, and audiovisual elements that can enhance or augment the user's environment.

[0004] One challenge in the design and fabrication of augmented reality devices is the display of virtual images superimposed on the surrounding environment. An augmented waveguide combiner is used to assist in this image superposition. First, the generated light is in-coupled to the augmented waveguide combiner and propagates through it. Then, the resulting light is out-coupled from the augmented waveguide combiner and superimposed on the surrounding environment. Surface-roughened gratings are used to couple the light into and out of the augmented waveguide combiner. Conventional designs may not be able to adequately control the intensity of the output coupled light.

[0005] Another challenge is that waveguide combiners may use gratings with different tilt angles depending on the desired properties of the augmented reality device. Furthermore, waveguide combiners may include gratings with different tilt angles to appropriately control the input and output coupling of light, and these tilt angles may have different angles from the grating vector.

[0006] Therefore, what is needed is an improved method for manufacturing waveguide combiners and gratings and grating masters. Summary of the Invention

[0007] In one or more embodiments, a method of forming a grating includes: etching a hard mask layer to form a plurality of openings, the hard mask layer being disposed on a grating material layer disposed on a substrate; and forming a first grating in the grating material layer through the plurality of openings in the hard mask layer, wherein the first grating has a first shape vector and a first grating vector. The first grating can be formed by: determining a first ion beam angle θ1, the first ion beam angle θ1 being related to a first tilt angle θ1' and an angle φ1 between the first shape vector and the first grating vector; and positioning a first portion of the grating material layer in the path of an ion beam, the ion beam being at the first ion beam angle θ1 relative to the substrate, the substrate being held on a platen. The method also includes: adjusting one or more process parameters when the ion beam is at the first ion beam angle θ1 to form a first plurality of fins of the first grating, the first plurality of fins having the first shape vector, the first grating vector, and the first tilt angle θ1' relative to a surface normal of the substrate, such that the first plurality of fins are formed at the first tilt angle θ1'. In some examples, the first grating is further formed by rotating the substrate about the central axis of the stage to a first rotation angle between the ion beam and the first grating vector of the first grating.

[0008] In some embodiments, a method of forming a grating includes: etching a first grating material layer to form a first feature in the first grating material layer, the first grating material layer being disposed on a substrate; depositing an etch stop layer in the first feature; depositing a second grating material layer on the etch stop layer; and depositing a hard mask layer on the second grating material layer. The method further includes: etching the hard mask layer to form a plurality of openings; and forming a first grating in the second grating material layer through the plurality of openings, wherein the first grating has a first shape vector and a first grating vector. The first grating can be formed by: determining a first ion beam angle θ1, the first ion beam angle θ1 being related to a first tilt angle θ1' and an angle φ1 between the first shape vector and the first grating vector; and positioning a first portion of the substrate relative to an ion beam at the first ion beam angle θ1, the substrate being held on a stage, and the first ion beam angle θ1 being measured relative to a plane parallel to the stage. The method also includes: adjusting one or more process parameters when the ion beam is at the first ion beam angle θ1 and in contact with the first portion of the substrate. In some examples, the process parameters may be or include the duty cycle of the ion beam, partial scanning of the ion beam, scanning speed of the ion beam, power supply for generating the ion beam, or any combination thereof.

[0009] In other embodiments, a method of forming a grating includes: etching a plurality of openings in a hard mask layer disposed on a grating material layer and the grating material layer disposed on a substrate; and etching the substrate through the plurality of openings in the hard mask layer to form a first grating in the grating material layer, the first grating including a plurality of fins formed in recesses, wherein the first grating has a first shape vector and a first grating vector. The first grating can be formed by: determining a first ion beam angle θ1, the first ion beam angle θ1 being related to a first tilt angle θ1' and an angle φ1 between the first shape vector and the first grating vector; and positioning a first portion of the grating material layer relative to an ion beam at the first ion beam angle θ1, the ion beam being adjustable relative to a plane parallel to the substrate in an angle range of about 15º to about 75º, the substrate being held on a worktable. The method further includes: when the ion beam is at the first ion beam angle θ1, rotating the substrate about the central axis of the stage to a first rotation angle between the ion beam and the first grating vector of the first grating; and etching the first grating at a first angle to remove the top portion of the plurality of fins to form a wedge shape, wherein the first shape vector is a wedge vector. Attached Figure Description

[0010] The foregoing features of this disclosure, as well as a more specific description of the disclosure briefly outlined above, can be understood in detail by referring to the embodiments (some of which are shown in the accompanying drawings). However, it should be noted that the drawings are merely illustrative of exemplary embodiments and should not be considered as limiting the scope of this disclosure; other equivalent embodiments are permissible.

[0011] Figure 1 A perspective front view depicting an enhanced waveguide combiner according to one or more embodiments described and discussed herein.

[0012] Figure 2A A schematic cross-sectional view of an angled etching system according to one or more embodiments described and discussed herein.

[0013] Figure 2B A schematic cross-sectional view of an angled etching system according to one or more embodiments described and discussed herein.

[0014] Figure 3 A schematic perspective view depicting a portion of a substrate having an angled grating according to one or more embodiments described and discussed herein.

[0015] Figure 4It is a flowchart illustrating a method for forming a grating according to one or more embodiments described and discussed herein.

[0016] Figures 5A to 5J The diagram illustrates one or more embodiments described and discussed herein. Figure 4 The structure of different intervals generated during the method described in the text.

[0017] Figure 6 This is a flowchart illustrating another method for forming a grating according to one or more embodiments described and discussed herein.

[0018] Figures 7A to 7G The diagram illustrates one or more embodiments described and discussed herein. Figure 6 The structure of different intervals generated during the method described in the text.

[0019] Figure 8 This is a flowchart illustrating another method for forming a grating according to one or more embodiments described and discussed herein.

[0020] Figures 9A to 9D The diagram illustrates one or more embodiments described and discussed herein. Figure 8 The structure of different intervals generated during the method described in the text.

[0021] Figure 10 This is a flowchart illustrating another method for forming a grating according to one or more embodiments described and discussed herein.

[0022] Figures 11A to 11D The diagram illustrates one or more embodiments described and discussed herein. Figure 10 The structure of different intervals generated during the method described in the text.

[0023] For ease of understanding, the same reference numerals have been used as much as possible to identify common elements in the figures. Elements and features of one embodiment are intended to be beneficially incorporated into other embodiments without further description. Detailed Implementation

[0024] Virtual and augmented reality devices utilizing gratings can employ depth-tuned tilted gratings, where the direction in which the wedge-shaped grating is formed may not be aligned with the grating vector. By using an ion beam capable of adapting to a range of angles to etch depth-tuned tilted gratings into the target material, gratings with different tilt angles and depth gradients can be formed. The manipulation of grating depth increases optical uniformity in optical devices such as waveguide combiners.

[0025] Using the systems and methods discussed herein, gratings with depth gradients misaligned with the grating vector are formed by rotating the substrate and adjusting process parameters (e.g., the duty cycle of the ion beam), thereby producing smooth gradient depth distributions relative to the orientations of the substrate. The systems and methods discussed herein can be used to form waveguide assemblies or other optical elements, and can be further used to form masters for imprinting waveguide assemblies or other optical elements. The gratings formed as discussed herein can be formed in a wedge shape or exhibit other cross-sectional shapes.

[0026] The grating discussed herein is a pattern formed in a target material layer, the pattern consisting of multiple fins separated by multiple troughs. The multiple fins can be formed with multiple depths and heights, and can be formed by etching the target material with an angled, adjustable ion beam and by rotating the substrate. The multiple fins are formed at an angle relative to the plane of the substrate. The grating can be formed with a cross-sectional geometry having a wedge-shaped, rectangular, or other polygonal or circular shape or combination of shapes. The grating can be formed and then modified in height and / or critical dimensions. Depending on the implementation, the critical dimensions discussed herein can refer to the fin height, pitch, width, or other dimensions of the grating.

[0027] The grating vector is measured perpendicular to the grating lines, and the grating vector is aligned with the tilt angle of the fins. The wedge direction (vector) can be measured by a change in the depth of the wedge-shaped grating, for example, the direction in which the depth of the fins of the wedge-shaped grating increases. In one or more examples, the wedge vector is the same as the scanning direction of the device, wherein a substrate is arranged to form the grating. The angle formed between the wedge vector and the grating vector can be combined with the tilt angle of the fins to determine the ion beam angle used to form the grating.

[0028] Figure 1 A perspective front view of an enhancement waveguide combiner 100 according to one or more embodiments is depicted. It should be understood that the enhancement waveguide combiner 100 described below is an exemplary enhancement waveguide combiner, and other enhancement waveguide combiners may be used in conjunction with or modified to complete aspects of this disclosure. The enhancement waveguide combiner 100 includes an input coupling region 102 defined by a first plurality of gratings 108, an intermediate region 104 defined by a second plurality of gratings 110, and an output coupling region 106 defined by a third plurality of gratings 112. The input coupling region 102 receives an incident beam of intensity from a microdisplay. Each of the plurality of gratings 108 divides the incident beam into multiple modes, each incident beam having one mode.

[0029] Different beam patterns respond differently to the enhancement waveguide combiner 100. For example, a zero-order mode (T0) beam is refracted back or lost in the enhancement waveguide combiner 100. In contrast to the T0 beam, a positive first-order mode (T1) beam is coupled to the intermediate region 104 through the enhancement waveguide combiner 100, and a negative first-order mode (T-1) beam propagates in the enhancement waveguide combiner 100 in the opposite direction to the T1 beam. Ideally, the incident beam is split into T1 beams with all the intensity of the incident beam to guide the virtual image to the intermediate region 104. In one or more embodiments, each of the plurality of gratings 108 is angled to suppress the T-1 and T0 beams. The T1 beam undergoes total internal reflection (TIR) ​​through the enhancement waveguide combiner 100 until it contacts the second plurality of gratings 110 in the intermediate region 104.

[0030] When the T1 beam contacts the gratings of the second plurality of gratings 110, the T1 beam is split into a T0 beam, a T1 beam, and a T-1 beam. The T0 beams are refracted back or lost in the enhancement waveguide combiner 100, and these T1 beams undergo TIR in the intermediate region 104 until the T1 beams contact another grating in the second plurality of gratings 110, and the T-1 beams are coupled to the output coupling region 106 through the enhancement waveguide combiner 100. The T1 beams undergoing TIR in the intermediate region 104 continue to contact the second plurality of gratings 110 until one of the following occurs: (1) the intensity of the T1 beams coupled to the intermediate region 104 through the enhancement waveguide combiner 100 is exhausted, or (2) the remaining T1 beams propagating through the intermediate region 104 reach the end of the intermediate region 104. The second plurality of gratings 110 are adjusted to control the T1 beams coupled to the intermediate region 104 through the beam waveguide combiner 100. Adjusting the second plurality of gratings 110 controls the intensity of the T-1 beam coupled to the output coupling region 106 to modulate the field of view of the virtual image generated by the microdisplay from the user's perspective and increase the user's viewing angle for the virtual image.

[0031] In one or more embodiments, the second plurality of gratings 110 may be referred to herein as a wedge shape and is defined by the tilt angle of the fins forming the wedge shape (discussed below), a first side 114, and an angled second side 116 opposite to the first side 114. The angled side 116 includes a first portion 116A and a second portion 116B. The second plurality of gratings 110 is further defined by a curved first end 118 and an angled second end defined by a first portion 120A and a second portion 120B. Depending on the embodiment, the curved first end 118 may take various curvatures. A first angle α is defined by the first portion 116A and the second portion 116B of the angled side 116. A second angle β is defined by the second portion 116B and the first portion 120A of the angled second end. A third angle γ may be defined by the first portion 120A and the second portion 120B of the angled second end. The fourth angle δ can be defined by the first side 114 and the second portion 120B of the angled second end. The systems and methods discussed herein form wedges or other shapes, wherein each fin of the second plurality of gratings 110 has a first end and a second end, the first end of which is positioned along the angled second side 116, and the second end of which is positioned along the first side 114. Each fin of the second plurality of gratings 110 can be further defined by various geometric features. For example, the first side of the fin can have a ramp (angle) such that each fin along the angled second side 116 has a ramp. The second side of each fin can have an undercut such that each fin along the first side 114 has an undercut.

[0032] Further in Figure 1 In this context, a depth gradient is defined in the direction from the first side 110A to the second side 110B of the plurality of gratings 110. Figure 1 This also illustrates the depth gradient for at least a second plurality of gratings 110 and a third plurality of gratings 112. Each depth gradient can be further defined by a depth gradient in a direction in which the depth of the fins of the gratings or plurality of gratings increases or decreases. Figure 1 The depth gradient is indicated by shading. For the second grating 110, the depth gradient increases from the first side 110A to the second side 110B, and from the top 112A to the bottom 112B of the third plurality of gratings 112. The grating vectors of the second plurality of gratings 110 (not shown here) are measured orthogonally to the second plurality of gratings 110. The wedge angle of the second plurality of gratings 110 can be defined as the angle between the grating vector and the depth gradient. Similarly, the grating vectors of the third plurality of gratings 112 (not shown here) are measured orthogonally to the third plurality of gratings 112.

[0033] The T-1 beam coupled to the output coupling region 106 via the enhancement waveguide combiner 100 undergoes a TIR within the enhancement waveguide combiner 100. The T-1 beam undergoes a TIR until it contacts one of the plurality of gratings 112, wherein the T-1 beam splits into: (a) a T0 beam, which is refracted back or lost in the enhancement waveguide combiner 100; (b) a T1 beam, which undergoes a TIR in the output coupling region 106 until it contacts another grating of the plurality of gratings 112; and (c) a T-1 beam, which is coupled out from the enhancement waveguide combiner 100. The T1 beam undergoing a TIR in the output coupling region 106 continues to contact the gratings of the plurality of gratings 112 until the intensity of the T-1 beam coupled to the output coupling region 106 via the enhancement waveguide combiner 100 is exhausted, or the remaining T1 beam propagating through the output coupling region 106 has reached the end of the output coupling region 106. Multiple gratings 112 must be adjusted to control the T-1 beam coupled to the output coupling region 106 through the enhancement waveguide combiner 100, so as to control the intensity of the T-1 beam coupled out from the enhancement waveguide combiner 100, thereby further adjusting the field of view of the virtual image generated from the microdisplay from the user's perspective, and further increasing the viewing angle of the virtual image that the user can view.

[0034] Figure 2A A schematic side cross-sectional view of an angled etching system 200 according to one or more embodiments is depicted, and Figure 2BA schematic side cross-sectional view of the angled etching system 200 is depicted. To form a grating with an angled tilt, a grating material 212 disposed on a substrate 210 is etched by the angled etching system 200. In one or more embodiments, the grating material 212 is disposed on an etch stop layer 211 disposed on the substrate 210, and a patterned hard mask 213 is disposed on the grating material 212. In one or more embodiments, the material of the grating material 212 is selected according to the tilt angle θ' of each grating and the refractive index of the substrate 210 to control the input and output coupling of light and to facilitate the propagation of light through the waveguide combiner. In some embodiments, the grating material 212 comprises a material containing silicon carbide (SiOC), titanium dioxide (TiO2), silicon oxide (e.g., silicon dioxide (SiO2)), vanadium oxide (IV) (VO2), aluminum oxide (Al2O3), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (SiN or Si3N4), titanium nitride (TiN), and / or zirconium dioxide (ZrO2). The refractive index of the grating material 212 is between about 1.5 and about 2.65. In yet another embodiment, the patterned hard mask 213 is an opaque hard mask that is removed after the waveguide combiner is formed. For example, the opaque hard mask comprises a reflective material such as chromium or silver.

[0035] In some embodiments, the patterned hard mask 213 is a transparent hard mask. In one or more embodiments, the etch stop layer 211 is an opaque etch stop layer that is removed after the waveguide combiner is formed. In some embodiments, the etch stop layer 211 is a transparent etch stop layer. The angled etch system 200 is configured to execute multiple instructions, for example using a controller (not shown), to form the angled grating discussed herein. The multiple instructions executed can include tilt angle, ion beam angle, variation of the ion beam angle during grating formation, wedge angle, depth gradient, and / or other aspects of the wedge to be formed from the grating.

[0036] An angled etching system 200 includes an ion beam chamber 202 housing an ion beam source 204. The ion beam source is configured to generate an ion beam 216, such as a strip beam, a dot beam, or a beam spanning the entire substrate size. The ion beam chamber 202 is configured to guide the ion beam 216 at an angle α relative to the surface normal 218 of the substrate 210. The substrate 210 is held on a stage 206 coupled to a first actuator 208. The first actuator 208 is configured to move the stage 206 in a scanning motion along the y-direction and / or z-direction. To form a grating with a tilt angle θ' relative to the surface normal 218, the ion beam source 204 generates the ion beam 216, and the ion beam chamber 202 guides the ion beam 216 to the substrate 210 at an angle α. The first actuator 208 positions the stage 206 such that the ion beam 216 contacts the grating material 212 at an ion beam angle θ, and etches a grating with a tilt angle θ' on the desired portion of the grating material 212. One or more process parameters (e.g., the duty cycle of the ion beam 216) can be adjusted to form multiple fins of the grating at varying depths.

[0037] Figure 3 A schematic perspective view of a portion 300 of a substrate 302 according to one or more embodiments is depicted. The ion beam angle θ is between about 0° and about 90°. The ion beam angle θ is adjustable during grating fabrication, preferably between about 15° and about 75°, because an ion beam angle θ close to about 0° or about 90° will cause the grating 304 to have a tilt angle θ' of about 0° or about 90°, so that the grating 304 is not tilted. Therefore, the tilt angle θ' can be determined by the relative orientation between the ion beam angle and the rotational position of the substrate. The substrate 302 is rotated about the x-axis 306 of the stage 206, such that there is a rotation angle ϕ between the grating vector before the rotation of the grating 304 and the grating vector after the rotation, said rotation angle ϕ being orthogonal to the grating 304 and measured. In order to form a wedge as discussed herein, the duty cycle of the ion beam and / or other process parameters can be controlled to change the etching depth.

[0038] In one or more examples, the process parameters can be or include the duty cycle of the ion beam, partial scanning of the ion beam, scanning speed of the ion beam, power supply (e.g., voltage) used to generate the ion beam, or any combination of the above parameters. In some examples, the duty cycle is controlled from about 5% to about 85%, where a 5% duty cycle forms shallow fins of the grating, while an 85% duty cycle forms the fins of the grating to a deeper depth. In other examples, the partial scanning of the ion beam, the scanning speed of the ion beam, and / or the power supply used to generate the ion beam can be controlled independently to form various depths of grating fins (e.g., from relatively shallow to relatively deep). While the formation of gratings with wedge-shaped cross-sections is discussed herein, in other examples, different gratings with varying depth gradients and tilt angles can be formed, thereby forming gratings with curved, bow-shaped, angled, flat, or other cross-sectional profiles (which are combinations of various geometries).

[0039] In one or more embodiments, the ion beam angle θ is aligned with the depth gradient of the grating. The depth gradient discussed above is a measurement of the change in depth of the grating throughout the fin, and the depth gradient is the direction of the change in fin depth. The ion beam angle θ can be determined by rotating the grating angle using the equation θ = atan(tan(θ') / cos(φ)), where θ = ion beam angle, θ' = fin tilt angle, and φ = angle between the shape vector (e.g., wedge vector) and the grating vector. The shape vector is the direction of the change in the depth gradient of the grating, e.g., the direction of increasing fin depth. The depth gradient is the change in depth of the grating throughout the fin. In one or more examples, for a 22.5° tilted grating, where the wedge is offset by 45° from the grating vector, θ = atan(tan(22.5°) / cos(45°)) ≈ 30.3°.

[0040] Figure 4 This is a flowchart illustrating a method 400 for forming a grating according to one or more embodiments. Figures 5A to 5J This describes the structures of the different sections produced during method 400. In method 400, at operation 402, the target stack is fabricated in multiple sub-operations capable of including chemical vapor deposition (CVD). Figure 5AThe image shows a target stack formed at operation 402, the target stack including a substrate 502 and a grating material layer 504 formed on the substrate 502. The target stack further includes a hard mask layer 506 formed on the grating material layer 504. The substrate 502 can be formed of a silicon-based material such as SiO2, and the hard mask layer 506 can be formed of a metallic material such as chromium or titanium, or a dielectric material such as silicon carbonitride (SiCN). The grating material layer 504 can include silicon oxycarbide (SiOC), titanium dioxide (TiO2), silicon dioxide (SiO2), vanadium oxide (VO2), aluminum oxide (Al2O3), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), titanium nitride (TiN), or zirconium dioxide (ZrO2). Figure 5A The stack shown can be fabricated using various sub-operations, including CVD. In one or more examples, the grating material layer 504 is 150 nm to 350 nm thick, and the hard mask layer 506 is about 15 nm to about 70 nm thick.

[0041] At operation 404, a continuous portion of the hard mask layer 506 is removed to form an opening 508 in the hard mask layer 506. Operation 404 can be performed using one or more chemicals in a wet stripping etch operation to form the opening 508. Figure 5B This illustrates the structure obtained by removing the portion of the hard mask layer 506 at operation 404. At operation 406, a portion of the grating material layer 504 is etched (or otherwise removed) to form feature 510. Figure 5C This illustrates the structure obtained due to the formation of feature 510 at operation 406. Operation 406 can be performed using selective area processing (SAP) etching to remove one or more portions of the grating material layer 504. During operation 406, SAP etching can be used to form feature 510, which can include various cross-sections, including but not limited to... Figure 5C The wedge-shaped cross-section of feature 510 shown. For example, although in Figure 5C Feature 510 is shown as wedge-shaped or triangular, but in other examples, various polygonal or combined shapes can be formed at operation 406 using SAP etching. Feature 510 can be referred to as a recess and is defined by a first side 510A, a transition surface 510B, and a second side 510C. The second side 510C is opposite to the first side 510A, and the transition surface 510B extends between the first side 510A and the second side 510C. The transition surface 510B is formed at an angle 512 relative to the substrate 502. Figure 5C In the example, the second side 510C is formed to a greater depth than the first side 510A.

[0042] In one or more embodiments, SAP etching can include a designed number of exposure cycles, wherein a given exposure cycle involves scanning the processing beam along a specific direction and subsequently rotating the substrate 502 to a new rotational position. In some examples, SAP etching can include 2 exposure cycles, 4 exposure cycles, 6 exposure cycles, 8 exposure cycles, or more exposure cycles. In some examples, SAP etching can include different exposure cycles, wherein the substrate 502 is positioned at different rotational positions such that each cycle is performed at a different rotational position. Additional aspects of SAP etching are described and discussed in U.S. Patent No. 10,269,663 (column 4, line 34 through column 7, line 61) and U.S. Patent No. 10,302,826, which are incorporated herein by reference.

[0043] At operation 408, an etch stop layer 514 is deposited on feature 510. Figure 5D The structure obtained by depositing an etch stop layer 514 at operation 408 is shown. The etch stop layer 514 can be deposited at operation 408 via CVD, atomic layer deposition (ALD), or another process that forms a conformal coating on feature 510. The etch stop layer 514 can be formed to a thickness of 15 nm to 50 nm. In one or more examples, the etch stop layer 514 is formed at operation 408 by a nitride such as tantalum nitride. In another example, the etch stop layer 514 is formed at operation 408 by a silicon-based material such as silicon oxide.

[0044] At operation 410, a second grating material layer 516 is deposited on the etch stop layer 514. The second grating material layer 516 can be deposited using CVD and formed on the inside of feature 510 and on either side of feature 510, thereby making material 516A excessive. Figure 5E The structure obtained by depositing the second grating material layer 516 at operation 410 is shown. In one or more embodiments, each of the grating material layer 504 and the second grating material layer 516 is formed of at least one of the following materials: silicon oxycarbonate (SiOC), titanium oxide (e.g., titanium dioxide (TiO2)), silicon oxide (e.g., silicon dioxide (SiO2)), vanadium (IV) oxide (VO2), aluminum oxide (Al2O3), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (SiN or Si3N4), titanium nitride (TiN), zirconium dioxide (ZrO2), oxynitrides of the above materials, or any combination of the above materials. The hard mask layer 506 is formed of silicon nitride, silicon oxide, a metal substrate containing titanium or chromium, a dopant of the above materials, an alloy of the above materials, or any combination of the above materials.

[0045] Subsequently, at operation 412, excess material is removed (planarized) from the second grating material layer 516 to form a planarized surface 518. Planarization at operation 412 can be performed using SAP etching. Figure 5F The structure obtained by planarization at operation 412 is shown. At operation 414, a second hard mask layer 520 is deposited on the second grating material layer 516 and etched to form a plurality of openings 522. Figure 5G The structure obtained by depositing a second hard mask layer 520 at operation 414 is shown. The second hard mask layer 520 can be deposited at operation 414 using CVD and etched using deep ultraviolet (DUV) lithography to form a plurality of openings 522 (e.g., patterning using DUV, which is then transferred to the hard mask layer 520 via an etching process). In other examples, the second hard mask layer 520 can be patterned using nanoimprint lithography (NIL) to form a plurality of openings 522. In one or more examples of operation 414, a plurality of openings 522 can be formed in a plurality of sub-operations including: depositing photoresist (not shown) on the second hard mask layer 520, performing DUV lithography to pattern the photoresist, and etching the second hard mask layer 520 through the patterned photoresist. The photoresist can then be removed prior to operation 416. The second hard mask layer 520 can be formed from a material similar to the material discussed above for forming the hard mask layer 506. In one or more examples, the second hard mask layer 520 is formed of a different material than the etch stop layer 514, such that the two materials have different etch selectivity.

[0046] At operation 416, a first grating 524, including a plurality of first fins 526, is formed in the second grating material layer 516 through a plurality of openings 522 in the second hard mask layer 520. Figure 5H The structure obtained by forming the first grating 524 at operation 416 is shown. It is possible to use... Figures 2A to 2B The angled etching system discussed above is used to perform operation 416 to form the first plurality of fins 526 at a first tilt angle. During operation 416, in order to form the first grating 524, a first portion of the substrate 502 is positioned relative to the ion beam at a first ion beam angle. Operation 416 includes determining a first ion beam angle θ1 of the first grating 524. As discussed above, the first ion beam angle θ1 can be determined by rotating from the grating angle of the first grating using the equation θ1 = atan(tan(θ1') / cos(φ1)).

[0047] The substrate 502 is held on a worktable, and a first ion beam angle is measured relative to a plane parallel to the worktable, as discussed above. When the ion beam is at the first ion beam angle, the substrate 502 rotates about the central axis of the worktable to a first rotation angle between the ion beam and the first grating vector of the first grating 524. The ion beam is a strip beam that forms an angle relative to the plane parallel to the worktable, the angle being adjustable from about 15 degrees to about 75 degrees. The first grating 524 has a first plurality of fins 526 such that the fins adjacent to a first end 524A of the first grating 524 are formed to a shallower depth than the fins adjacent to a second end 524B of the first grating 524. In one or more examples, the depth of the first grating is from about 10 nm to about 400 nm, and the width of each of the plurality of fins 526 is from about 30% to about 70% of the spacing between the plurality of fins 526. The plurality of fins 526 are formed at a first tilt angle as discussed above, the first tilt angle being adjustable from about 0 degrees to about 60 degrees. Multiple fins 526 can be associated with a first depth gradient, such that the height from the first side 524A to the second side 524B of the grating 524 increases, thereby increasing the etching depth. The height variation of the fins 526 along the bottom surface 524C can create a wedge angle 528. The ion beam has one or more process parameters (e.g., duty cycle) that can be tuned to form the first grating 524. For example, the process parameters when the ion beam is at a first ion beam angle and in contact with a first portion of the substrate can be tuned between about 5% and about 85% of the duty cycle. Shorter tuning times for the process parameters (e.g., 5%) can be used to form fins with shallower depths, such as those at or near the first end 524A of the first grating 524. Similarly, longer tuning times for the process parameters (e.g., 85%) can be used to form fins with greater relative depths, such as those at or near the second end 524B of the first grating. In one or more embodiments, the first ion beam angle for forming the first grating 524 in operation 416 is aligned with the first depth gradient of the first grating 524.

[0048] In one or more embodiments, after the formation of the first grating 524, additional fins can be formed during subsequent repetitions of operation 416. In this example, at operation 416, after the formation of the first grating, the first ion beam angle is changed to a second ion beam angle different from the first ion beam angle. Subsequent repetitions of operation 416 include determining a subsequent ion beam angle θ. X The subsequent ion beam angle θ XThe second ion beam angle θ2 can be determined, for example, to be different from the first ion beam angle θ1. As discussed above, the second ion beam angle θ2 can be determined using the equation θ2 = atan(tan(θ2') / cos(φ2)). When the ion beam is positioned at the second ion beam angle, the second portion of the substrate is positioned in the path of the ion beam. When the ion beam is at the second ion beam angle, the substrate is rotated about the central axis of the stage to a second rotation angle between the ion beam and the second grating vector of the second grating. Therefore, at operation 416, multiple gratings can be formed on a single substrate with different tilt angles and different depth gradients by changing the ion beam angle and rotating the substrate.

[0049] At operation 418, for example, the second hard mask layer 520 is removed by using a wet stripping etch as discussed above with respect to operation 404. Figure 5I The structure obtained by removing the second hard mask layer 520 at operation 418 is shown. In some embodiments of method 400, at operation 420, a coating 526A is optionally formed on a plurality of fins 526 using an ALD process. In one or more examples, coating 526A comprises one or more layers of oxide. Figure 5J The diagram shows the structure obtained by forming a coating on multiple fins 526 at operation 420. In examples where more than one grating is formed, some or all of the gratings can be coated at operation 420. In one or more examples, an ALD process can be used at operation 420 to coat the multiple fins 526 with oxide. In some examples, other methods for forming conformal coatings on the multiple fins 526 can be employed. In one or more examples, multiple fins 526 can be coated at operation 420 to adjust or refine the critical dimensions of the multiple fins 526.

[0050] Figure 6 This is a flowchart illustrating a method 600 for forming a grating according to one or more embodiments described and discussed herein. Figures 7A to 7G This shows the structure of the different intervals generated during method 600. Method 600 includes operations 402, 404, and 406, which have been described above. Figure 4 Method 400 in the text has been discussed in detail. Figure 7A The structure formed by operation 402 is described, the structure including a substrate 502, a grating material layer 504, and a hard mask layer 506. Figure 7B The structure formed by operation 404 is described, wherein, as discussed above in method 400, an opening 508 is formed in the hard mask layer 506 using wet stripping (chemical) etching. Figure 7C This describes the structure formed by operation 406 after a portion of the first grating layer 504 is removed to form feature 510. Similar to... Figure 5C As shown, feature 510 can refer to a recess or an angled recess, and is defined by a first side 510A, a second side 510C opposite to the first side 510A, and a transition surface 510B extending between the first side 510A and the second side 510C. An angle 512 is formed between the transition surface 510B and the second side 510C. However, in Figure 6 In method 600, in contrast to method 400 in which an etch stop layer and a second grating material layer are deposited after operation 406, a hard mask layer 702 is deposited at operation 602. The hard mask layer 702 can be deposited at operation 602 using CVD. Figure 7D The structure obtained by the deposition of hard mask layer 702 at operation 602 is shown. Hard mask layer 702 can be formed of a material similar to the material discussed above with respect to hard mask layer 506 and second hard mask layer 520.

[0051] Subsequently, at operation 604, a hard mask layer 702 (which can be referred to here as a second hard mask layer) is etched to form a plurality of openings 704. Figure 7E This illustrates the structure obtained by forming an opening in the hard mask layer 702 at operation 604. In some examples, during operation 604, multiple portions 710 of the hard mask layer 702 are also removed from the grating material layer 504. Multiple openings 704 can be formed in multiple sub-operations, including: depositing photoresist (not shown) on the hard mask layer 702, performing DUV lithography to pattern the photoresist, and etching the hard mask layer 702 with the patterned photoresist. The photoresist can then be removed before operation 606. In other examples, multiple openings 704 can be formed at operation 604 using NIL.

[0052] At operation 606, a grating 706 can be formed by angled etching to include a plurality of fins 708 formed at an angle and with a depth gradient and wedge angle as discussed above. Operation 606 includes determining a first ion beam angle θ1 for forming the grating 706. As discussed above, the first ion beam angle θ1 can be determined by using the equation θ1 = atan(tan(θ1') / cos(φ1)). Figure 7F The structure obtained by forming the grating 706 at operation 606 is shown. It can be used in conjunction with... Figure 4The grating 706 formed at operation 606 is formed in a manner similar to that discussed in operation 416, which is achieved by rotating the substrate 502 and changing the ion beam angle using an angled etching system. For example, the grating 706 formed at operation 606 can be formed by angled etching, which is achieved by rotating the substrate 502 about a central axis perpendicular to the substrate and / or on which the substrate is disposed. An ion beam (e.g., a ribbon beam) is positioned relative to the substrate 502 at a predetermined angle, and the ion beam is used to form the plurality of fins 708 to varying depths by adjusting the duty cycle of the ion beam. Operation 606 can be repeated in a manner similar to the repeated operation of operation 416 discussed above to form a plurality of gratings with varying tilt angles, depth gradients, and wedge angles. As discussed above, each ion beam angle θ can be determined for each grating subsequently formed at operation 606. X At operation 608 of method 600, one or more portions 710 of the grating material layer 504 are removed from the grating 706 using SAP etching, thereby forming a wedge 712. Figure 7G The wedge shape 712 is obtained by forming multiple fins 708 of the grating 706 after removing multiple portions 710 of the grating material layer 504 at operation 608. Figure 7G Further shown is wedge 712, in which the hard mask layer 702 is removed, which can occur in operation 608 or other operations not discussed herein.

[0053] Figure 8 This is a flowchart illustrating a method 800 for forming a grating according to one or more embodiments described and discussed herein. Figures 9A to 9D The structures of the different regions produced during method 800 are described. At operation 802 in method 800, a substrate including a grating material layer 902 is formed using, for example, CVD. Figure 9A The structure obtained by forming a grating material layer 902 at operation 802 is explained. Specifically, Figure 9A A grating material layer 902 is displayed, which can be formed by CVD from a silicon-based material to a thickness of about 200 nm to about 400 nm, wherein the silicon-based material is derived from at least one of the following: silicon oxycarbonate (SiOC), silicon oxide (e.g., silicon dioxide (SiO2)), silicon nitride (SiN or Si3N4), or silicon carbonitride (SiCN). A hard mask layer 904 is formed on the grating material layer 902 and can be formed from a metal or dielectric material, as discussed above with respect to methods 400 and 600.

[0054] At operation 804, multiple openings 906 are formed in the hard mask layer 904. Figure 9BThe structure obtained by forming the hard mask layer 904 in operation 804 is shown. At operation 804, multiple openings 906 can be formed in multiple sub-operations, including: depositing photoresist (not shown) on the hard mask layer 904, performing DUV lithography and etching or NIL to pattern the photoresist, and etching the hard mask layer 904 through the patterned photoresist. The photoresist can then be removed before operation 806. Figure 9C The structure obtained by etching the hard mask layer 904 at operation 804 is shown.

[0055] At operation 806, a grating 908 is formed in the grating material layer 902 from silicon using an angled etching system as discussed herein. Operation 806 includes determining a first ion beam angle θ1 for forming the grating 908. As discussed above, the first ion beam angle θ1 can be determined using the equation θ1 = atan(tan(θ1') / cos(φ1)). The grating 908 can be formed as a wedge-shaped grating, wherein the plurality of fins 910 of the grating 908 increase in size from a first end 908A of the grating 908 to a second end 908B of the grating 908. At operation 806, the grating 908 can be formed in a manner similar to the gratings in operations 416 and 606 described above. The duty cycle of the ion beam, configured with an adjustable angle, is controlled to form each of the plurality of fins 910 to a varying depth, and the substrate on which the grating material layer 902 is disposed can also be rotated. In contrast to method 400, no etch stop layer is used in method 800. At operation 808, the hard mask layer 904 is removed, for example, by chemical etching through wet stripping. Figure 9D The structure obtained by removing the hard mask layer 904 at operation 808 is shown.

[0056] Figure 10 This is a flowchart illustrating a method 1000 for forming a grating according to one or more embodiments described and discussed herein. Figures 11A to 11D This describes the structure of the different intervals generated during method 1000. Method 1000 includes operation 402, which is based on... Figure 4 The operation is performed in a similar manner to operation 402 in method 400. Figure 11A The structure obtained by operation 402 in method 1000 is shown. Figure 11A This shows a grating material layer 504 formed on the substrate 502 and a hard mask layer 506 formed on the grating material layer. At operation 1002, using DUV lithography and etching or NIL, the hard mask layer 506 is opened to form a plurality of openings 1101 in a manner similar to operations 404 and 804 discussed above. Figure 11BThe structure obtained by opening the hard mask layer 506 at operation 1002 in method 1000 is shown. This contrasts with operation 404 in method 400, in which a continuous portion of the hard mask layer is removed. Subsequently, in operation 1004 of method 1000, as discussed above, a grating 1104 is formed in the grating material layer 504 by rotating the substrate 502 and controlling the duty cycle of the ion beam using angled etching. Operation 1004 includes determining a first ion beam angle θ1 for forming the grating 1104. As discussed above, the first ion beam angle θ1 can be determined using the equation θ1 = atan(tan(θ1') / cos(φ1)). Figure 11C This shows the structure obtained by forming grating 1104 in operation 1004 of method 1000. Grating 1104 is formed having a plurality of fins 1106, a first end 1104A, a second end 1104B, and a bottom 1104C, and is formed to have a rectangle such that the first end 1104A and the second end 1104B are substantially right-angled with the bottom 1104C. In operation 1006, a portion of the fins 1106 is removed using SAP to form the top surface 1108 of grating 1104, such that grating 1104 has a wedge-shaped cross-section. This contrasts with the rectangle formed in operation 1004. Further in operation 1006, a plurality of portions 504A of the grating material layer 504 (in...) Figure 11C (As shown in the image) was removed, just as hard mask layer 1102 was also removed. Figure 11D The structure obtained by etching the grating 1104 at operation 1006 in method 1000 is shown. The portion of fin 1106 removed at operation 1006 is removed at a wedge angle α measured relative to substrate 502. Operations 1002, 1004, and 1006 can be repeated to form additional gratings in the grating material layer 504 at other tilt angles using different ion beam angles, different substrate rotation angles, and duty cycle tuning as discussed herein.

[0057] Implementations of this disclosure further relate to any one or more of the following paragraphs 1-29:

[0058] 1. A method of forming a grating, comprising: etching a hard mask layer to form a plurality of openings, the hard mask layer being disposed on a grating material layer, the grating material layer being disposed on a substrate; forming a first grating in the grating material layer through the plurality of openings in the hard mask layer, wherein the first grating has a first shape vector and a first grating vector, wherein forming the first grating comprises: according to the equation θ1 = atan(tan(θ1') / The first ion beam angle θ1 is determined by cos(φ1), where θ1' is the first tilt angle and φ1 is the angle between the first shape vector and the first grating vector; a first portion of the grating material layer is positioned in the path of the ion beam, the ion beam being at the first ion beam angle θ1 relative to the substrate, the substrate being held on the worktable; the substrate is rotated about the central axis of the worktable to a first rotation angle, the first rotation angle being between the ion beam and the first grating vector of the first grating; and when the ion beam is at the first ion beam angle θ1, process parameters are adjusted to form a first plurality of fins of the first grating, the first plurality of fins having the first shape vector, the first grating vector, and the first tilt angle θ1' relative to the surface normal of the substrate, thereby forming the first plurality of fins at the first tilt angle θ1'.

[0059] 2. A method of forming a grating, comprising: etching a first grating material layer to form a first feature in the first grating material layer disposed on a substrate; depositing an etch stop layer in the first feature; depositing a second grating material layer on the etch stop layer; depositing a hard mask layer on the second grating material layer; etching the hard mask layer to form a plurality of openings; and forming a first grating in the second grating material layer through the plurality of openings, wherein the first grating has a first shape vector and a first grating vector, wherein forming the first grating comprises: according to the equation θ1 = atan(tan(θ1') / The first ion beam angle θ1 is determined by cos(φ1), where θ1' is the first tilt angle and φ1 is the angle between the first shape vector and the first grating vector; the first portion of the substrate is positioned relative to the ion beam at the first ion beam angle θ1, the substrate is held on the worktable, and the first ion beam angle θ1 is measured relative to a plane parallel to the worktable; when the ion beam is at the first ion beam angle θ1, the substrate is rotated about the central axis of the worktable to a first rotation angle between the ion beam and the first grating vector of the first grating; and when the ion beam is at the first ion beam angle θ1 and in contact with the first portion of the substrate, process parameters are adjusted.

[0060] 3. A method of forming a grating, comprising: etching a plurality of openings in a hard mask layer, the hard mask layer being disposed on a grating material layer and the grating material layer being disposed on a substrate; etching the substrate through the plurality of openings in the hard mask layer to form a first grating in the grating material layer, the first grating including a plurality of fins formed in recesses, wherein the first grating has a first shape vector and a first grating vector, wherein forming the first grating includes: determining a first ion beam angle θ1 according to the equation θ1=atan(tan(θ1') / cos(φ1)), where θ1' is a first tilt angle and φ1 is the first shape vector. The angle between the first grating vector and the first grating; positioning a first portion of the grating material layer relative to the ion beam at the first ion beam angle θ1, the ion beam being adjustable relative to a plane parallel to the substrate in an angle range of about 15º to about 75º, the substrate being held on a worktable; and rotating the substrate about the central axis of the worktable to a first rotation angle between the ion beam and the first grating vector of the first grating when the ion beam is at the first ion beam angle θ1; and etching the first grating at a first angle to remove the top portions of the plurality of fins to form a wedge shape, wherein the first shape vector is a wedge vector.

[0061] 4. A method of forming a grating, comprising: etching a hard mask layer to form a plurality of openings, the hard mask layer being disposed on a grating material layer disposed on a substrate; forming a first grating in the grating material layer through the plurality of openings in the hard mask layer, wherein the first grating has a first shape vector and a first grating vector, wherein forming the first grating comprises: determining a first ion beam angle θ1, the first ion beam angle θ1 being related to a first tilt angle θ1' and an angle φ1 between the first shape vector and the first grating vector; positioning a first portion of the grating material layer in the path of an ion beam, the ion beam being at the first ion beam angle θ1 relative to the substrate, the substrate being held on a worktable; and when the ion beam is at the first ion beam angle θ1, adjusting process parameters to form a first plurality of fins of the first grating, the first plurality of fins having the first shape vector, the first grating vector, and the first tilt angle θ1' relative to a surface normal of the substrate, such that the first plurality of fins are formed at the first tilt angle θ1'.

[0062] 5. A method of forming a grating, comprising: etching a first grating material layer to form a first feature in the first grating material layer disposed on a substrate; depositing an etch stop layer in the first feature; depositing a second grating material layer on the etch stop layer; depositing a hard mask layer on the second grating material layer; etching the hard mask layer to form a plurality of openings; and forming a first grating in the second grating material layer through the plurality of openings, wherein the first grating has a first shape vector and a first grating vector, wherein forming the first grating comprises: determining a first ion beam angle θ1, the first ion beam angle θ1 being related to a first tilt angle θ1' and an angle φ1 between the first shape vector and the first grating vector; positioning a first portion of a substrate relative to an ion beam at the first ion beam angle θ1, the substrate being held on a stage, and the first ion beam angle θ1 being measured relative to a plane parallel to the stage; and adjusting process parameters when the ion beam is at the first ion beam angle θ1 and in contact with the first portion of the substrate.

[0063] 6. A method of forming a grating, comprising: etching a plurality of openings in a hard mask layer, the hard mask layer being disposed on a grating material layer and the grating material layer being disposed on a substrate; etching the substrate through the plurality of openings in the hard mask layer to form a first grating in the grating material layer, the first grating including a plurality of fins formed in recesses, wherein the first grating has a first shape vector and a first grating vector, wherein forming the first grating includes: determining a first ion beam angle θ1, the first ion beam angle θ1 being relative to a first tilt angle θ1' and a distance between the first shape vector and the first grating vector. Related to angle φ1; positioning a first portion of the grating material layer relative to the ion beam at a first ion beam angle θ1, the ion beam being adjustable relative to a plane parallel to the substrate within an angle range of approximately 15º to approximately 75º, the substrate being held on a worktable; and when the ion beam is at the first ion beam angle θ1, rotating the substrate about the central axis of the worktable to a first rotation angle between the ion beam and the first grating vector of the first grating; and etching the first grating at a first angle to remove the top portions of the plurality of fins to form a wedge shape, wherein the first shape vector is a wedge vector.

[0064] 7. The method described in any of paragraphs 1-6, wherein the first ion beam angle θ1 is determined according to the equation θ1 = atan(tan(θ1') / cos(φ1)).

[0065] 8. The method according to any one of paragraphs 1-7, further comprising: rotating the substrate about the central axis of the stage to a first rotation angle between the ion beam and the first grating vector of the first grating.

[0066] 9. The method according to any one of paragraphs 1-8, further comprising: forming a second grating in the grating material layer, the second grating including a second plurality of fins having a second shape vector and a second grating vector, wherein forming the second grating includes: determining a second ion beam angle θ2, the second ion beam angle θ2 being related to a second tilt angle θ2' and an angle φ2 between the second shape vector and the second grating vector; positioning a second portion of the grating material layer in a second path of the ion beam at the second ion beam angle θ2 to form the second grating in the grating material layer; rotating the substrate about the central axis of the stage such that a second rotation angle is generated between the ion beam and the second grating vector of the second grating; and adjusting process parameters when the ion beam is at the second ion beam angle θ2 to form the second plurality of fins, the second plurality of fins being formed at the second tilt angle θ2' and having the second shape vector and the second grating vector.

[0067] 10. The method according to any one of paragraphs 1-9, wherein the second rotation angle is different from the first rotation angle, and wherein the second ion beam angle θ2 is determined according to the equation θ2 = atan(tan(θ2') / cos(φ2).

[0068] 11. The method according to any one of paragraphs 1-10, wherein the ion beam is a ribbon beam.

[0069] 12. The method according to any one of paragraphs 1-11, wherein the first ion beam angle θ1 is about 15° to about 75° with respect to a plane perpendicular to the substrate.

[0070] 13. The method according to any one of paragraphs 1-12, further comprising: forming a second grating in the grating material layer, the second grating including a second plurality of fins having a second shape vector and a second grating vector, wherein forming the second grating includes: determining a second ion beam angle θ2 according to the equation θ2 = atan(tan(θ2') / cos(φ2)), where θ2' is a second tilt angle and φ2 is the angle between the second shape vector and the second grating vector; positioning a second portion of the grating material layer in a second path of the ion beam at the second ion beam angle θ2 to form the second grating in the grating material layer; rotating the substrate about the central axis of the stage such that a second rotation angle is generated between the ion beam and the second grating vector of the second grating; and adjusting process parameters to form the second plurality of fins at the second ion beam angle θ2, the second plurality of fins being formed at the second tilt angle θ2' and having the second shape vector and the second grating vector.

[0071] 14. The method described in any of paragraphs 1-13, wherein the second rotation angle is different from the first rotation angle.

[0072] 15. The method according to any of paragraphs 1-14, wherein the process parameters include the duty cycle of the ion beam, partial scanning of the ion beam, scanning speed of the ion beam, power supply for generating the ion beam, or any combination of the above process parameters.

[0073] 16. The method according to any one of paragraphs 1-15, further comprising removing the hard mask layer after forming the first grating.

[0074] 17. The method according to any one of paragraphs 1-16, wherein the grating material layer comprises one or more of the following: silicon oxycarbonate, silicon oxide, silicon carbonitride, silicon nitride, or any combination of the above materials.

[0075] 18. The method according to any one of paragraphs 1-17, wherein each of the first grating material layer and the second grating material layer comprises one or more of the following: silicon oxide, titanium dioxide, silicon oxide, vanadium oxide, aluminum oxide, indium tin oxide, zinc oxide, tantalum pentoxide, silicon nitride, titanium nitride, or zirconium dioxide.

[0076] 19. The method according to any one of paragraphs 1-18, wherein the hard mask layer comprises silicon oxide, silicon nitride, or a combination of the above materials.

[0077] 20. The method according to any one of paragraphs 1-19, wherein the first feature includes a recess and is defined by a first side, a second side, and a third side, the first side being formed to reach a first depth in the first grating material layer, the second side being defined by a second depth in the first grating material layer, the third side extending between the first side and the second side, the first depth being less than the second depth.

[0078] 21. The method according to any one of paragraphs 1-20, wherein the first grating comprises a plurality of fins having a first tilt angle θ1' relative to the surface normal of the substrate.

[0079] 22. The method according to any one of paragraphs 1-21, wherein the height of the first plurality of fins decreases according to a first depth gradient from the first side of the recess to the second side of the recess.

[0080] 23. The method according to any one of paragraphs 1-22, wherein the first ion beam angle θ1 is aligned with the first depth gradient of the first grating.

[0081] 24. The method according to any one of paragraphs 1-23, further comprising: removing the hard mask layer; and coating the first plurality of fins with an oxide layer.

[0082] 25. The method according to any one of paragraphs 1-24, further comprising: after forming the first grating, changing the first ion beam angle θ1 to a second ion beam angle θ2 different from the first ion beam angle θ1; and forming a second grating in the second grating material layer, the second grating comprising a second plurality of fins having a second shape vector and a second grating vector, wherein forming the second grating comprises: according to the equation θ2 = atan(tan(θ2') / The second ion beam angle θ2 is determined by cos(φ2), where θ2' is the second tilt angle and φ2 is the angle between the second shape vector and the second grating vector; the second portion of the substrate is positioned in the path of the ion beam at the second ion beam angle θ2; and when the ion beam is at the second ion beam angle θ2, the substrate is rotated about the central axis of the stage to a second rotation angle between the ion beam and the second grating vector of the second grating, wherein the ion beam contacts the second grating material layer at the second ion beam angle θ2 to form the second plurality of fins, the second plurality of fins having the second tilt angle θ2', the second shape vector, and the second grating vector.

[0083] 26. The method according to any one of paragraphs 1-25, further comprising: after depositing the second grating material layer and before forming the first grating in the second grating material layer, planarizing the substrate in which the first grating is formed to remove a portion of the second grating material layer.

[0084] 27. The method according to any one of paragraphs 1-26, further comprising: forming a conformal oxide coating on the plurality of fins.

[0085] 28. The method according to any one of paragraphs 1-27, further comprising: forming a second grating in the grating material layer, the second grating comprising a second plurality of fins, a second shape vector, and a second grating vector, wherein forming the second grating comprises: according to the equation θ2 = atan(tan(θ2') / The second ion beam angle θ2 is determined by cos(φ2), where θ2' is the second tilt angle and φ2 is the angle between the second shape vector and the second grating vector; a second portion of the substrate is positioned in the path of the ion beam at the second ion beam angle θ2 to form a second grating in the grating material layer; the substrate is rotated about the central axis of the stage to generate a second rotation angle between the ion beam and the second grating vector of the second grating; when the ion beam is at the second ion beam angle θ2, process parameters are adjusted to form a second plurality of fins, the second plurality of fins having a second tilt angle θ2' relative to the surface normal of the substrate and having the second shape vector and the second grating vector, wherein the process parameters include the duty cycle of the ion beam, partial scanning of the ion beam, scanning speed of the ion beam, power supply for generating the ion beam, or any combination of the above process parameters.

[0086] 29. An apparatus or system for performing the method described in any of paragraphs 1-28.

[0087] Therefore, using the systems and methods discussed herein, it is possible to fabricate multiple gratings for enhancing waveguide combiners and / or master grating materials for imprinting. By using the embodiments discussed herein, it is possible to form gratings with varying depth gradients and tilt angles on a single substrate, achieved by at least changing the ion beam angle and controlling the duty cycle of the ion beam in combination with rotating the substrate relative to said ion beam angle.

[0088] While the foregoing describes embodiments of this disclosure, other and further embodiments may be devised without departing from the essential scope of this disclosure, the scope of which is defined by the appended claims. All documents described herein are incorporated by reference, including any priority documents and / or test procedures to the extent that they are not inconsistent with this document. It will be apparent from the foregoing general description and detailed description that, although the form of this disclosure has been illustrated and described, various modifications are possible without departing from the spirit and scope of this disclosure. Therefore, it is not intended that this disclosure be limited thereto. Similarly, for legal purposes, the term “comprising” is considered synonymous with the term “including.” Likewise, whenever the conjunction “comprising” precedes a component, element, or group of elements, it should be understood that we also consider the same component or group of elements: preceded by the conjunctions “substantially constitutes,” “consisting of,” “selected from the group consisting of,” or “is,” and vice versa.

[0089] Certain implementations and features have been described using a set of upper and lower numerical limits. It should be understood that, unless otherwise stated, the scope covers a range including any combination of two values, such as any lower value combined with any higher value, any combination of two lower values, and / or any combination of two higher values. Certain lower, upper, and range limits are presented in one or more of the following claims.

Claims

1. An optical device, comprising: A grating material layer is disposed on a substrate, and the grating material layer comprises: A first grating in the grating material layer, wherein the first grating includes a first plurality of fins, the first plurality of fins having a first tilt angle, a first shape vector, and a first grating vector, wherein the direction of the first shape vector is from a first side of the first grating to a second side of the first grating, wherein the second side is opposite to the first side and a first transition surface extends between the first side and the second side and increases in depth relative to the substrate from the first side to the second side; and A second grating in the grating material layer, wherein the second grating includes a second plurality of fins, the second plurality of fins having a second tilt angle, a second shape vector, and a second grating vector, wherein the direction of the second shape vector is from a first side of the first second grating to a second side of the second grating, wherein the second side of the second grating is opposite to the first side of the second grating and a second transition surface extends between the first side and the second side of the second grating and increases in depth relative to the substrate from the first side to the second side of the second grating, and wherein the second tilt angle is different from the first tilt angle and the second grating vector is different from the first grating vector, wherein... The second grating is defined by a first side and an angled second side opposite to the first side, the angled second side comprising a first portion and a second portion, and the second grating is further defined by a curved first end and an angled second end, the angled second end being defined by the first portion and the second portion, wherein... The first angle α is defined by the first portion of the second side of the angle and the second portion of the second side of the angle, the second angle β is defined by the second portion and the first portion of the second end of the angle, the third angle γ is defined by the first portion of the second end of the angle and the second portion, and the fourth angle δ is defined by the first side and the second portion of the second end of the angle.

2. The optical device of claim 1, wherein the second shape vector is different from the first shape vector, and wherein the second transition surface is different from the first transition surface.

3. The optical device of claim 1, wherein the grating material layer is composed of at least one of the following: silicon dioxide, titanium oxide, titanium dioxide, silicon oxide, silicon dioxide, vanadium (IV), aluminum oxide, indium tin oxide, zinc oxide, tantalum pentoxide, silicon nitride, titanium nitride, zirconium dioxide, or oxynitride.

4. The optical device of claim 1, wherein the first grating has a depth of about 10 nm to about 400 nm, and wherein the width of each of the first plurality of fins is in the range of about 30% to about 70% of the spacing between the first plurality of fins.

5. The optical device of claim 1, wherein the first plurality of fins or the second plurality of fins has a coating formed thereon.

6. The optical device of claim 5, wherein the coating comprises one or more layers of oxide.

7. The optical device of claim 1, wherein the first plurality of fins or the second plurality of fins has a conformal coating formed thereon, wherein the conformal coating is a coating of the same form as the first plurality of fins or the second plurality of fins.

8. An optical device, comprising: a substrate; a grating material layer disposed on the substrate, the grating material layer comprising: a first grating in the grating material layer, wherein the first grating comprises a first plurality of fins having a first tilt angle, a first shape vector, and a first grating vector, wherein a direction of the first shape vector is in a direction from a first side of the first grating to a second side of the first grating, wherein the first grating has a depth of about 10 nm to about 400 nm, wherein each fin of the first plurality of fins has a width in a range of about 30% to about 70% of a pitch of the first plurality of fins, wherein the second side is opposite the first side and a first transition surface extends between the first side and the second side and increases in depth relative to the substrate from the first side to the second side; and a second grating in the grating material layer, wherein the second grating comprises a second plurality of fins having a second tilt angle, a second shape vector, and a second grating vector, wherein a direction of the second shape vector is in a direction from a first side of the second grating to a second side of the second grating, wherein the second side of the second grating is opposite the first side of the second grating and a second transition surface extends between the first side and the second side of the second grating and increases in depth relative to the substrate from the first side to the second side of the second grating, and wherein the second tilt angle is different from the first tilt angle and the second grating vector is different from the first grating vector; wherein the second grating is bounded by a first side and an angled second side opposite the first side, the angled second side comprises a first portion and a second portion, and the second grating is further bounded by a curved first end and an angled second end, the angled second end is bounded by the first portion and the second portion, and wherein a first angle a is bounded by the first portion of the angled second side and the second portion of the angled second side, a second angle b is bounded by the second portion and the first portion of the angled second end, a third angle g is bounded by the first portion of the angled second end and the second portion, and a fourth angle d is bounded by the first side and the second portion of the angled second end.

9. The optical device of claim 8, wherein the second shape vector is different from the first shape vector, and wherein the second transition surface is different from the first transition surface.

10. The optical device of claim 8, wherein the grating material layer is comprised of at least one of silicon oxynitride, titanium oxide, titanium dioxide, silicon oxide, silicon dioxide, vanadium (IV) oxide, aluminum oxide, indium tin oxide, zinc oxide, tantalum pentoxide, silicon nitride, titanium nitride, zirconium dioxide, or oxynitride.

11. The optical device of claim 8, wherein the first plurality of fins or the second plurality of fins has a coating formed thereon.

12. The optical device of claim 11, wherein the coating comprises one or more layers of oxide.

13. The optical device of claim 8, wherein the first plurality of fins or the second plurality of fins has a conformal coating formed thereon, wherein the conformal coating is a coating of the same form as the first plurality of fins or the second plurality of fins.

14. An optical device, comprising: a first grating material layer disposed on a substrate, the first grating material layer having a wedge angle from a top surface of the first grating material layer to the substrate; and a second grating material layer disposed over the first grating material layer, the second grating material layer comprising: a first grating formed on the substrate, wherein the first grating comprises a first plurality of fins having a first tilt angle, a first shape vector, and a first grating vector, wherein a direction of the first shape vector is in a direction from a first side of the first grating to a second side of the first grating, wherein the first grating has a depth of about 10 nm to about 400 nm, wherein each fin of the first plurality of fins has a width in a range of about 30% to about 70% of a pitch of the first plurality of fins, wherein the second side is opposite the first side and a first transition surface extends between and increases in depth from the first side and the second side relative to the substrate; and a second grating formed on the substrate, wherein the second grating comprises a second plurality of fins having a second tilt angle, a second shape vector, and a second grating vector, wherein a direction of the second shape vector is in a direction from a first side of the first grating to a second side of the second grating, wherein the second side of the second grating is opposite the first side of the second grating and a second transition surface extends between and increases in depth from the first side and the second side of the second grating relative to the substrate. wherein the second grating is bounded by a first side and an angled second side opposite the first side, the angled second side includes a first portion and a second portion, and the second grating is further bounded by a curved first end and an angled second end, the angled second end is bounded by the first portion and the second portion, and wherein a first angle a is bounded by the first portion of the angled second side and the second portion of the angled second side, a second angle b is bounded by the second portion and the first portion of the angled second end, a third angle g is bounded by the first portion of the angled second end and the second portion, and a fourth angle d is bounded by the first side and the second portion of the angled second end.

15. The optical device of claim 14, wherein the first tilt angle is different from the second tilt angle, and wherein the second shape vector is different from the first shape vector.

16. The optical device of claim 15, wherein the second grating vector is different from the first grating vector, and wherein the second transition surface is different from the first transition surface.

17. The optical device of claim 14, wherein the first grating is comprised of at least one of silicon oxycarbide, titanium oxide, titanium dioxide, silicon oxide, silicon dioxide, vanadium (IV) oxide, aluminum oxide, indium tin oxide, zinc oxide, tantalum pentoxide, silicon nitride, titanium nitride, zirconium dioxide, or oxynitride.

18. The optical device of claim 17, wherein the second grating is comprised of at least one of silicon oxycarbide, titanium oxide, titanium dioxide, silicon oxide, silicon dioxide, vanadium (IV) oxide, aluminum oxide, indium tin oxide, zinc oxide, tantalum pentoxide, silicon nitride, titanium nitride, zirconium dioxide, or oxynitride.

19. The optical device of claim 14, wherein the first plurality of fins has a coating formed thereon, and wherein the coating includes one or more layers of an oxide.

20. The optical device of claim 19, wherein the second plurality of fins has a coating formed thereon, and wherein the coating includes one or more layers of an oxide.

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