Method of forming an optical device

Abstract

A method for forming an optical device is provided. In one example, the method may include providing a mask layer atop a substrate, the mask layer including a first opening located above a first processing region and a second opening located above a second processing region. The method may also include etching the substrate to recess the first and second processing regions; forming a grating material over the substrate; and etching the grating material in the first and second processing regions to form a plurality of structures oriented at a non-zero angle relative to a perpendicular line extending from a top surface of the substrate.

Description

Technical Field

[0001] The present disclosure generally relates to processing of grating materials. More particularly, the present disclosure relates to a method of producing variable depth grating materials, a method of forming an optical device. Background Art

[0002] Optical elements, such as optical lenses, have long been used to manipulate light for various advantages. More recently, micro-diffraction gratings have been used in holographic and augmented / virtual reality (AR and VR) devices. One particular AR and VR device is a wearable display system, such as a headset arranged to display an image at a short distance from the human eye. Such a wearable headset is sometimes referred to as a head-mounted display and is provided with a frame that displays an image within a few centimeters of the user's eye. The image may be a computer-generated image on a display (e.g., a microdisplay). The optical components are arranged to deliver light of the desired image (where the light is generated on the display) to the user's eye so that the image is visible to the user. The display that generates the image may form part of a light engine, such that the image generates a collimated light beam that is guided by the optical components to provide an image visible to the user.

[0003] The optical assembly may include structures with different tilt angles, such as the fins of one or more gratings, formed on a substrate using an angled etch system. An example of an angled etch system is an ion beam chamber that houses an ion beam source. The ion beam source is configured to generate an ion beam, such as a ribbon beam, a point beam, or a beam the size of the entire substrate. The ion beam chamber is configured to guide the ion beam at an angle relative to the surface normal of the substrate to generate a structure with a specific tilt angle. Changing the tilt angle of the structure to be generated by the ion beam requires a lot of reconfiguration of the hardware of the ion beam chamber.

[0004] Gray-tone lithography has typically been used to form optical devices comprising different structures having different depths across the surface of a substrate. However, gray-tone lithography is a time-consuming and complex process that adds significant cost to devices fabricated using the process.

[0005] Therefore, there is a need for improved methods and related apparatus for forming optical devices including different structures having different tilt angles and / or different depths across a single substrate. Summary of the Invention

[0006] This disclosure is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This disclosure is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be an aid in determining the scope of the claimed subject matter.

[0007] According to one embodiment, a method may include providing a mask layer atop a substrate, the mask layer including a first opening located above a first processing region and a second opening located above a second processing region. The method may further include etching the substrate to recess the first and second processing regions; forming a grating material over the substrate; and etching the grating material in the first and second processing regions to form a plurality of structures oriented at a non-zero angle relative to a perpendicular line extending from a top surface of the substrate.

[0008] According to another embodiment, a method of forming an optical device may include providing a mask layer atop a substrate, the mask layer including a first opening defining a first processing region and a second opening defining a second processing region. The method may further include etching the substrate to recess the first and second processing regions; forming an optical grating material over the substrate; and forming a plurality of structures by etching a plurality of trenches into the optical grating material in the first and second processing regions, wherein the plurality of structures are oriented at a non-zero angle relative to a perpendicular line extending from a top surface of the substrate.

[0009] According to another embodiment, a method may include providing an ion beam source within a chamber, wherein the chamber is operable to deliver the ion beam to a substrate, and wherein the substrate includes a first processing region separated from a second processing region by a mask element. The method may further include: etching the substrate to recess the first processing region and the second processing region, wherein the first processing region and the second processing region are recessed to different depths relative to a top surface of the substrate; forming an optical grating material above the substrate; and forming a plurality of structures by etching a plurality of trenches into the optical grating material in the first processing region and the second processing region, wherein the plurality of structures are oriented at a non-zero angle relative to a perpendicular line extending from the top surface of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings illustrate exemplary embodiments of the present disclosure, including practical applications of the principles of the present disclosure, and are as follows:

[0011] Figure 1 is a perspective front view of an optical device according to an embodiment of the present disclosure.

[0012] Figure 2Ais a side schematic cross-sectional view of an angled etch system according to an embodiment of the present disclosure.

[0013] Figure 2B According to the embodiment of the present disclosure Figure 2A A top schematic cross-sectional view of the angled etching system shown in FIG.

[0014] Figure 3A A side cross-sectional view of an optical grating assembly formed from grating material according to an embodiment of the present disclosure is shown.

[0015] Figure 3B The embodiment according to the present disclosure is shown Figure 3A Front view of the optical grating assembly shown.

[0016] Figures 4 to 9 A process for forming a grating device according to an embodiment of the present disclosure is shown.

[0017] Figure 10 is a flow chart of a method for forming a grating device according to an embodiment of the present disclosure.

[0018] The accompanying drawings are not necessarily drawn to scale. The accompanying drawings are merely representative diagrams and are not intended to depict specific parameters of the present disclosure. The accompanying drawings are intended to illustrate exemplary embodiments of the present disclosure and are therefore not to be considered limiting in scope. In the accompanying drawings, like numbers represent like elements.

[0019] Furthermore, for clarity of illustration, certain elements may be omitted or not shown to scale in some of the figures. For clarity of illustration, cross-sectional views may be presented as "slices" or "near-sighted" cross-sectional views, and certain background lines that would otherwise be visible in a "true" cross-sectional view may be omitted. Furthermore, for clarity, some reference numbers may be omitted in some of the figures.

[0020] [Explanation of Symbols]

[0021] 100: Devices / Optical Devices;

[0022] 102: Raster / Input Raster;

[0023] 104: grating / intermediate grating;

[0024] 106: grating / output grating;

[0025] 108, 110, 112: structure;

[0026] 200: Angled etching system / system;

[0027] 202: ion beam chamber;

[0028] 204: ion beam source;

[0029] 205: devices;

[0030] 206: platen;

[0031] 208: first actuator;

[0032] 210, 310, 410: substrate;

[0033] 211, 311: etch stop layer;

[0034] 212: grating material;

[0035] 213: Hard mask / patterned hard mask / non-transparent hard mask;

[0036] 216: ion beam;

[0037] 218: surface normal;

[0038] 220: second actuator;

[0039] 222: Structure / Fin;

[0040] 300: optical grating assembly;

[0041] 312: grating materials / optical grating materials;

[0042] 313: top surface;

[0043] 322: Structure / Angled Structure / Angled Components;

[0044] 325A: first groove / groove;

[0045] 325B: Second groove / groove;

[0046] 325N, 462: groove;

[0047] 331: Part I;

[0048] 333: Part II;

[0049] 400: Optical grating devices / devices;

[0050] 404: mask layer;

[0051] 412: grating material;

[0052] 413: Hard mask;

[0053] 420: First opening;

[0054] 422: first processing area;

[0055] 424: Second opening;

[0056] 426: second processing area;

[0057] 428: mask element;

[0058] 430, 455: etching;

[0059] 431: vertical line;

[0060] 432: top surface;

[0061] 434: blocking element;

[0062] 435: shadow mask;

[0063] 444: First set of openings;

[0064] 446: Second set of openings;

[0065] 448: a first plurality of hard mask segments;

[0066] 450: a second plurality of hard mask segments;

[0067] 460: structure;

[0068] 460A: The first set of inclined structures;

[0069] 460B: The second set of inclined structures;

[0070] 462A: first plurality of grooves;

[0071] 462B: second plurality of grooves;

[0072] 1000:method;

[0073] 1010, 1020, 1030, 1040: blocks;

[0074] AW1, AW2: average width;

[0075] d1, d2: depth;

[0076] D1: first depth;

[0077] D2: second depth;

[0078] OW1, OW2: opening width;

[0079] SG1, SG2: segment width;

[0080] W1: first width;

[0081] W2: second width;

[0082] x, y, z: axis / direction;

[0083] α: first ion beam angle;

[0084] β: non-zero angle / tilt angle;

[0085] Second ion beam angle / ion beam angle;

[0086] Tilt angle;

[0087] θ: non-zero angle. DETAILED DESCRIPTION

[0088] The devices, systems, and methods according to the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. The devices, systems, and methods can be embodied in many different forms and are not to be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the devices, systems, and methods to those skilled in the art.

[0089] Figure 1 1 is a perspective front view of a device 100 (e.g., an optical device) according to an embodiment of the present disclosure. Examples of the optical device 100 include, but are not limited to, planar optical devices and waveguides (e.g., waveguide combiners). The optical device 100 includes one or more structures, such as gratings. In one embodiment, which may be combined with other embodiments described herein, the optical device 100 includes an input grating 102, an intermediate grating 104, and an output grating 106. Each of the gratings 102, 104, 106 includes a corresponding structure 108, a structure 110, a structure 112 (e.g., a fin). In one embodiment, which may be combined with other embodiments described herein, the structures 108, 110, 112, and the depths therebetween include sub-micrometer critical dimensions (e.g., nanometer-sized critical dimensions) that may vary in one or more dimensions across the optical device 100.

[0090] Figure 2A is an angled etch system (hereinafter "system") 200 (available, for example, from Applied Materials, Inc., Santa Clara, California). (Varian ) system) is a side schematic cross-sectional view, and Figure 2B is a top schematic cross-sectional view of the angled etch system 200. It should be understood that the system 200 described below is an exemplary angled etch system that can be used or modified to form the structures described herein on substrates, as well as other angled etch systems, including those from other manufacturers.

[0091] Figure 2A to Figure 2B A device 205 is shown disposed on a platen 206. The device 205 may include a substrate 210, an etch stop layer 211 disposed over the substrate 210, an etch layer to be etched (e.g., a grating material 212 disposed over the etch stop layer 211), and a hard mask 213 disposed over the grating material 212. It should be understood that in other embodiments, the device 205 may include different layered materials and / or combinations. For example, the etch layer may be a blanket film to be processed, such as a photoresist-type material or an optically transparent material (e.g., silicon or silicon nitride). The blanket film may be processed using a selective area processing (SAP) etch cycle to form one or more sloped or curved surfaces of the device 205. In another embodiment, the etch stop layer 211 may not be present.

[0092] To form structures (e.g., fins) 222 with tilt angles, the grating material 212 may be etched by the system 200. In one embodiment, the grating material 212 is disposed on an etch stop layer 211 disposed on the substrate 210. In one embodiment, the grating material 212 is disposed on an etch stop layer 211 disposed on the substrate 210. and the refractive index of the substrate 210 to select one or more materials of the grating material 212. In some embodiments, the grating material 212 comprises a material containing one or more of the following: silicon oxycarbide (SiOC), titanium dioxide (TiO2), silicon dioxide (SiO2), vanadium (IV) oxide (VO x ), aluminum oxide (Al2O3), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), titanium nitride (TiN), and / or zirconium dioxide (ZrO2). The grating material 212 can have a refractive index between about 1.5 and about 2.65.

[0093] In some embodiments, patterned hard mask 213 is a non-transparent hard mask that is removed after forming device 205. For example, non-transparent hard mask 213 may include a reflective material such as chromium (Cr) or silver (Ag). In another embodiment, patterned hard mask 213 is a transparent hard mask. In one embodiment, etch stop layer 211 is a non-transparent etch stop layer that is removed after forming device 205. In another embodiment, etch stop layer 211 is a transparent etch stop layer.

[0094] The system 200 may include an ion beam chamber 202 housing an ion beam source 204. The ion beam source 204 is configured to generate an ion beam 216, such as a ribbon beam, a spot beam, or a full-substrate-sized beam. The ion beam chamber 202 is configured to direct the ion beam 216 at a first ion beam angle α relative to a surface normal 218 of a substrate 210. Changing the first ion beam angle α may require reconfiguring the hardware of the ion beam chamber 202. The substrate 210 is retained on a platen 206 coupled to a first actuator 208. The first actuator 208 is configured to move the platen 206 in a scanning motion along the y-direction and / or the z-direction. In one embodiment, the first actuator 208 is further configured to tilt the platen 206 so that the substrate 210 is positioned at a tilt angle β relative to the x-axis of the ion beam chamber 202. In some embodiments, the first actuator 208 may be further configured to tilt the platen 206 relative to the y-axis and / or the z-axis.

[0095] After the substrate 210 is tilted, the first ion beam angle α and the tilt angle β form a second ion beam angle α relative to the surface normal 218 of the substrate 210. In order to form a surface having an inclination angle relative to the surface normal 218 In the structure of FIG. 2 , the ion beam source 204 generates an ion beam 216, and the ion beam chamber 202 directs the ion beam 216 toward the substrate 210 at a first ion beam angle α. The first actuator 208 positions the stage 206 so that the ion beam 216 is directed at a second ion beam angle α. Contacting the grating material 212 and etching the grating material 212 to form a grating having a tilt angle on a desired portion of the grating material 212 structure.

[0096] Conventionally, in order to form a structure having an inclined angle with adjacent parts of the structure, Different tilt angles or in order to form different tilt angles on a continuous substrate The first ion beam angle α is changed, the tilt angle β is changed, and / or multiple angled etching systems are used. Reconfiguring the hardware of the ion beam chamber 202 to change the first ion beam angle α is complex and time consuming. When the ion beam 216 contacts the grating material 212 at different energy levels, the tilt angle β is adjusted to modify the ion beam angle This can result in structures on portions of the substrate 210 having uneven depths. For example, a portion located closer to the ion beam chamber 202 will have structures having greater depths than structures in adjacent portions located further from the ion beam chamber 202. Using multiple angled etching systems increases fabrication time and costs due to the need for multiple chambers. To avoid reconfiguring the ion beam chamber 202, adjusting the tilt angle β to modify the ion beam angle and using multiple angled etch systems, the angled etch system 200 may include a second actuator 220 coupled to the platen 206 to rotate the substrate 210 relative to the x-axis of the platen 206 to control the tilt angle of the structure.

[0097] During use, the ion beam 216 can be extracted while applying a voltage difference using a bias power supply between the ion beam chamber 202 and the substrate 210 or substrate platen, as in known systems. The bias power supply can be coupled to the ion beam chamber 202, for example, where the ion beam chamber 202 and the substrate 210 are maintained at the same electrical potential.

[0098] The trajectories of the ions within the ion beam 216 may be parallel to one another or may lie within a narrow angular spread, for example, within 10 degrees or less of one another. In other embodiments, the trajectories of the ions within the ion beam 216 may converge or diverge from one another, for example, in a fan shape. In various embodiments, the ion beam 216 may be provided as a ribbon-shaped reactive ion beam that is extracted as a continuous beam or a pulsed ion beam, as in known systems.

[0099] In various embodiments, a gas (e.g., a reactive gas) can be supplied to the ion beam chamber 202 from a source. Depending on the exact composition of the species provided to the ion beam chamber 202, the plasma can produce various etching or deposition species. The ion beam 216 can be composed of any convenient gas mixture, including inert gases, reactive gases, and in some embodiments, can be provided in combination with other gas species. In some embodiments, the ion beam 216 and other reactive species can be provided to the substrate 210 as an etch recipe to perform directional reactive ion etching (RIE) of a layer, such as the grating material 212. As is known in the art, such an etch recipe can use known reactive ion etching chemistries to etch materials, such as oxides or other materials. In other embodiments, the ion beam 216 can be formed from an inert species in which the ion beam 216 is provided to etch the substrate 210, or more specifically, the grating material 212, by physical sputtering as the ion beam 216 is scanned relative to the substrate 210.

[0100] Figure 3A A side cross-sectional view of an optical grating assembly 300 formed from a grating material 312 is shown according to an embodiment of the present disclosure. Figure 3B FIG. 3 shows a front view of an optical grating assembly 300. As shown in the figure, the optical grating assembly 300 includes a substrate 310 and an optical grating material 312 disposed on the substrate 310. The optical grating assembly 300 can be used with Figure 1The input grating 102, intermediate grating 104, and / or output grating 106 are shown to be identical or similar. In some embodiments, substrate 310 is an optically transparent material, such as glass as is known in the art. In some embodiments, substrate 310 is silicon. In the latter case, substrate 310 is silicon, and another process is used to transfer the grating pattern to a film on the surface of another optical substrate (e.g., glass or quartz). The embodiments are not limited in this context. Figure 3A and Figure 3B In the illustrated non-limiting embodiment, the optical grating assembly 300 further includes an etch stop layer 311 disposed between the substrate 310 and the grating material 312. In other embodiments, no etch stop layer is present between the substrate 310 and the grating material 312.

[0101] In some embodiments, the optical grating assembly 300 may include a plurality of angled structures, shown as angled assemblies or structures 322 separated by grooves 325A through 325N. The structures 322 may be disposed at a non-zero tilt angle (φ) relative to the plane of the substrate 310 (e.g., the yz plane) and perpendicular to the top surface 313 of the grating material 312. The angled structures 322 may be included within one or more fields of tilted gratings that together form a "microlens."

[0102] exist Figure 3A In the illustrated example, the angled structures 322 and the grooves 325A-325N define variable heights along a direction parallel to the y-axis. For example, the depth 'd1' of the first groove 325A in the first portion 331 of the optical grating assembly 300 may differ from the depth 'd2' of the second groove 325B in the second portion 333 of the optical grating assembly 300. In some embodiments, the widths of the angled structures 322 and / or the grooves 325 may also vary, for example, along the y-direction.

[0103] The angled structure 322 can be achieved by scanning the substrate 310 relative to the ion beam using a process recipe. Briefly, the process recipe can vary at least one of a set of process parameters, thereby having the effect of varying, for example, the etch rate or deposition rate caused by the ion beam during scanning of the substrate 310. Such process parameters can include the scan rate of the substrate 310, the ion energy of the ion beam, the duty cycle of the ion beam when provided as a pulsed ion beam, the spread angle of the ion beam, and the rotational position of the substrate 310. The etch profile can be further varied by varying the quality of the ion beam across the mask. The quality can include intensity / etch rate, such as current that varies with duty cycle or beam shape at different angles. In at least some embodiments herein, the process recipe can also include the material of the grating material 312 and the chemistry of the etching ions of the ion beam. In still other embodiments, the process recipe can include the initial geometry of the grating material 312, including dimensions and aspect ratio. The embodiments described are not limited in this context.

[0104] Now go to Figures 4 to 9 , the process for forming the optical grating device 400 according to the embodiment of the present disclosure will be described. Figure 4 As shown in FIG, a mask layer 404 is provided atop a substrate 410. The mask layer 404 can be patterned or otherwise processed to include a first opening 420 located above a first processing region 422 and a second opening 424 located above a second processing region 426. It should be understood that the first processing region 422 and the second processing region 426 can correspond to regions of the substrate 410 where optical gratings or other semiconductor trenches / structures are to be formed. As shown, the first processing region 422 can be separated from the second processing region by a mask element 428 of the mask layer 404. The first opening 420 can have a first width 'W1' (e.g., along the y-direction) and the second opening 424 can have a second width 'W2', where W2>W1. Although not shown, the mask layer 404 can also include a third opening defining a third processing region.

[0105] Next, if Figure 5A As shown in FIG, in order to recess the substrate 410 in the first processing region 422 and the second processing region 426, the device 400 may be etched 430. The etch 430 may be an ion etch performed at an angle parallel to a perpendicular line 431 extending from the top surface 432 of the substrate 410. In other embodiments, the etch 430 may be performed at a non-zero angle relative to the perpendicular line 431. Furthermore, it should be understood that the etch 430 may represent one or more etch cycles.

[0106] In some embodiments, as Figure 5BAs shown in FIG, a blocking element 434 can be formed over the second opening 424 to prevent the second processing region 426 from being affected by one or more etching cycles of the etch 430. For example, the first processing region 422 can be etched for one or more etching cycles while the blocking element 434 is present over the second processing region 426. The blocking element 434 can then be removed, and both the first processing region 422 and the second processing region 426 can be etched simultaneously. Although not limiting, the blocking element 434 can be a gray tone (GT) resist film that is etched away, thereby allowing the etch 430 to affect the second processing region 426 after the first processing region 422. The blocking element 434 can be a hard mask (e.g., a Cr hard mask) that is deposited as a thin film and patterned photolithographically.

[0107] like Figures 5C to 5D As shown in FIG, in another embodiment, the blocking element can be an adjacent or shadow mask 435, such as a metal or other material positioned above the substrate 410. The shadow mask 435 can include a plurality of openings formed therethrough that allow the ion beam of the etchant 430 to pass toward the substrate 410. The shadow mask 435 can be separated from the substrate by a gap or distance (e.g., along the x-direction). In other words, the shadow mask 435 is typically not formed directly atop the device substrate 410. However, in alternative embodiments, the shadow mask 435 can be in direct physical contact with the device 400, with one or more edges defining at least one of the plurality of openings through the shadow mask 435 being spaced apart or raised above the substrate 410 to produce a shadowing effect.

[0108] exist Figure 5C In the illustrated embodiment, the etch 430 may be an ion etch performed at an angle parallel to a perpendicular line 431 extending from a top surface 432 of the substrate 410. Figure 5D In the illustrated embodiment, etching 430 may be performed at a non-zero angle θ relative to vertical 431 .

[0109] Each of the openings of the shadow mask 435 can be formed by a leading edge (e.g., Figure 5D Each of the openings may also be defined by a first side edge (e.g., an edge of the opening along the z-direction) opposite to a second side edge (e.g., an edge of the opening along the z-direction). It should be understood that the openings may take on virtually any number, shape, or configuration. Furthermore, it should be understood that the one or more openings of the shadow mask 435 may take on a unique or different shape / configuration than the remaining openings. The embodiments herein are not limited in this context.

[0110] In some non-limiting embodiments, the shadow mask 435 may further include a plurality of raised surface features along the leading edge, trailing edge, and / or side edges of the openings. The raised surface features may extend above a plane defined by the top surface of the shadow mask 435. In some embodiments, the shadow mask 435 may additionally or alternatively include surface features that extend below a plane defined by the bottom surface of the shadow mask. It should be understood that the surface features may partially block the ion beam of the etchant 430, thereby affecting the amount, angle, and / or depth of the ion beam that passes through the corresponding opening and strikes the substrate 410.

[0111] like Figure 6 As shown in FIG, as a result of etching 430, substrate 410 is recessed relative to a top surface 432 of substrate 410 in first and second processing regions 422, 426. In some embodiments, substrate 410 is recessed to a first depth 'D1' in first processing region 422 and to a second depth 'D2' in second processing region 426, where D1>D2. In other embodiments, substrate 410 is recessed to the same or substantially the same depth in both first and second processing regions 422, 426. As shown, the top surface of substrate 410 in first and second processing regions 422, 426 may be sloped or curved.

[0112] like Figure 7 As shown in FIG, a grating material 412 may then be formed over the device 400 (e.g., on top of the substrate 410). The grating material 412 extends into the first processing region 422 and the second processing region 426. A hard mask 413 may then be formed over the grating material 412. In some embodiments, the mask layer 404 may be removed prior to depositing the grating material 412. Figure 6 In some embodiments, an etch stop layer (not shown) may be formed on the device 400 after removing the mask layer 404 but before depositing the grating material 412. The grating material 412 may be an optical grating material made of one or more of the following: silicon oxycarbide (SiOC), titanium dioxide (TiO2), silicon dioxide (SiO2), vanadium (IV) oxide (VO x ), aluminum oxide (Al2O3), indium tin oxide (ITO), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), titanium nitride (TiN), and / or zirconium dioxide (ZrO2). Hard mask 413 may be a non-transparent hard mask, for example, comprising a reflective material such as chromium (Cr) or silver (Ag). In another embodiment, hard mask 413 is a transparent hard mask.

[0113] The hard mask 413 may then be patterned, such as Figure 8As shown in . In some embodiments, a first set of openings 444 may be formed substantially above the first processing region 422, while a second set of openings 446 may be formed substantially above the second processing region 426. As shown, a first plurality of hard mask segments 448 are separated from each other by the first set of openings 444. Each of the first plurality of hard mask segments 448 may have a segment width 'SG1'. Similarly, a second plurality of hard mask segments 450 are separated from each other by the second set of openings 446, wherein the second plurality of hard mask segments 450 have a segment width 'SG2'. As shown, SG2>SG1. In other embodiments, SG1 and SG2 may be equal or approximately equal. Furthermore, each of the first set of openings 444 may have an opening width 'OW1' and each of the second set of openings 446 may have an opening width 'OW2'. In various embodiments, OW1 and OW2 may be the same or different.

[0114] Next, if Figure 9 As shown in FIG, the device 400 can be etched 455 to form a plurality of structures 460 and a plurality of trenches 462. More specifically, the grating material 412 can be etched at a non-zero angle β relative to a perpendicular line 431 extending from the top surface 432 of the substrate 410 to form a first set of tilted structures 460A and a second set of tilted structures 460B. Ions of the etch 455 can pass through the first set of openings 444 to form a first plurality of trenches 462A, and ions of the etch 455 can pass through the second set of openings 446 to form a second plurality of trenches 462B. In an exemplary embodiment, each of the first plurality of trenches 462A and the second plurality of trenches 462B has a substantially flat bottom at the intersection of the substrate 410 and the grating material 412.

[0115] As shown, the depth between two or more grooves in the first plurality of grooves 462A can vary. Similarly, the depth between two or more grooves in the second plurality of grooves 462B can vary. In some embodiments, the average width 'AW1' of the first set of structures 460A can be different from the average width 'AW2' of the second set of structures 460B. In other embodiments, AW1 is equal to AW2. In addition, the angle of the first set of structures 460A can be the same as or different from the angle of the second set of structures 460B. Once the first set of structures 460A and the second set of structures 460B are completed, the device 400 includes a plurality of diffractive optical elements. Although not limiting, the first set of structures 460A can correspond to an input grating, while the second set of structures 460B can correspond to an intermediate grating or an output grating.

[0116] Go to Figure 10, a method 1000 according to an embodiment of the present disclosure will be described. As shown, at block 1010, method 1000 may include providing a mask layer atop a substrate, the mask layer including a first opening located above a first processing region and a second opening located above a second processing region. In some embodiments, the mask layer further includes a third opening located above a third processing region.

[0117] At block 1020, method 1000 may include etching the substrate to recess the first and second processed regions. The etching may be an ion etch performed at an angle parallel to a vertical line extending from the top surface of the substrate. In other embodiments, the etching may be performed at a non-zero angle relative to the vertical line.

[0118] In some embodiments, a blocking element may be formed above the second opening to prevent the second processing region from being affected by the etching. In one embodiment, the first processing region may be etched for one or more etching cycles while the blocking element is present above the second processing region. The blocking element may then be removed, and both the first and second processing regions may be etched simultaneously. In some embodiments, the first and second processing regions are recessed to different depths.

[0119] At block 1030, the method 1000 may further include forming a grating material over the substrate (including over the recessed first and second processing regions). In some embodiments, the grating material is an optical grating material formed atop the substrate after the mask layer has been removed.

[0120] At block 1040, method 1000 may further include etching the grating material in the first processing region and the second processing region to form a plurality of structures oriented at a non-zero angle relative to a perpendicular extending from the top surface of the substrate. In some embodiments, the grating material is etched to form a first plurality of trenches and a second plurality of trenches. In some embodiments, the method includes varying the etch depth between two or more trenches in the first plurality of trenches, and varying the etch depth between two or more trenches in the second plurality of trenches. In some embodiments, the plurality of structures includes a first group of structures and a second group of structures, wherein the first group of structures has a first average structure width, wherein the second group of structures has a second average structure width, and wherein the first average structure width is different from the second average structure width.

[0121] For convenience and clarity, terms such as "top," "bottom," "upper," "lower," "vertical," "horizontal," "lateral," and "longitudinal" will be used herein to describe the relative placement and orientation of components and their constituent parts as they appear in the drawings. The terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.

[0122] Unless explicitly stated to exclude plural elements or operations, elements or operations described in the singular and preceded by the word "a" or "an" as used herein are to be understood to include plural elements or operations. Furthermore, reference to "one embodiment" of the present disclosure is not intended to be limiting. Additional embodiments may also include the described features.

[0123] Furthermore, in some embodiments, the terms "substantial" or "essentially" and the terms "approximately" or "approximately" may be used interchangeably and may be described using any relative measure acceptable to one of ordinary skill in the art. For example, these terms may be used as a comparison to a reference parameter to indicate a deviation from the ability to provide the intended function. Although not limiting, the deviation from the reference parameter may be, for example, less than 1%, less than 3%, less than 5%, less than 10%, less than 15%, less than 20%, and the like.

[0124] Furthermore, persons of ordinary skill will understand that when an element, such as a layer, region, or substrate, is referred to as being formed, deposited, or disposed “on,” “over,” or “atop” another element, the element can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on,” “directly over,” or “directly atop” another element, there are no intervening elements present.

[0125] In various embodiments, a design tool can be provided and configured to create data sets for patterning layers of the grating materials and diffractive optical elements described herein. For example, a data set can be created to generate photomasks used during photolithography operations to pattern layers of structures such as those described herein. Such a design tool can include a collection of one or more modules and can also include hardware, software, or a combination thereof. Thus, for example, a tool can be a collection of one or more software modules, hardware modules, software / hardware modules, or any combination or permutation thereof. As another example, a tool can be a computing device or other apparatus running software or implemented in hardware.

[0126] As used herein, a module can be implemented using any form of hardware, software, or a combination thereof. For example, one or more processors, controllers, application specific integrated circuits (ASICs), programmable logic arrays (PLAs), logic components, software routines, or other mechanisms can be implemented to constitute a module. In an embodiment, the various modules described herein can be implemented as discrete modules, or the functions and features described can be partially or completely shared between one or more modules. In other words, it will be apparent to those of ordinary skill in the art after reading this description that the various features and functions described herein can be implemented in any given application. In addition, the various features and functions can be implemented in various combinations and arrangements in one or more separate or shared modules. Although the various features or elements of a function can be individually described or declared as separate modules, it will be understood by those of ordinary skill in the art that these features and functions can be shared between one or more shared software and hardware elements.

[0127] By utilizing the embodiments described herein, a waveguide with regions having variable etch depths is formed. A first technical advantage of the waveguide of the present embodiment includes improved manufacturing efficiency by eliminating more time-consuming and difficult processes. Furthermore, a second technical advantage of the grating structure of the present embodiment includes providing two-dimensional or three-dimensional shapes, enabling the waveguide to be used in a wider range of applications.

[0128] The scope of the present disclosure is not limited by the specific embodiments described herein. In fact, in addition to the embodiments described herein, various other embodiments and modifications of the present disclosure will be apparent to those of ordinary skill in the art from the above description and accompanying drawings. Therefore, such other embodiments and modifications are intended to fall within the scope of the present disclosure. In addition, the present disclosure has been described herein in the context of specific embodiments, in specific circumstances, and for specific purposes. Those of ordinary skill in the art will recognize that the usefulness is not limited thereto, and that the present disclosure can be advantageously implemented in any number of circumstances and for any number of purposes. Therefore, the claims set forth above are to be interpreted in light of the entire breadth and spirit of the disclosure as set forth herein.

Claims

1. A method for forming an optical device, comprising: providing a mask layer atop the substrate, the mask layer comprising a first opening overlying the first processing region and a second opening overlying the second processing region; Etching the substrate to form the first processed region having a first depth and the second processed region having a second depth different from the first depth; forming a grating material on the substrate having the first processing region and the second processing region formed thereon; as well as The grating material is etched in the first and second processed regions to form a plurality of structures oriented at a non-zero angle relative to a perpendicular extending from a top surface of the substrate. 2 . The method of forming an optical device according to claim 1 , further comprising etching the grating material to form a first plurality of grooves and a second plurality of grooves. 3 . The method of forming an optical device according to claim 2 , further comprising varying an etch depth between two or more of the first plurality of trenches, and varying an etch depth between two or more of the second plurality of trenches. The method of forming an optical device according to claim 1 , wherein the plurality of structures comprises a first group of structures and a second group of structures.

5. The method of forming an optical device of claim 4, wherein the first set of structures has a first average structure width, wherein the second set of structures has a second average structure width, and wherein the first average structure width is different from the second average structure width. 6 . The method for forming an optical device according to claim 1 , wherein the mask layer further comprises a third opening located above the third processing region.

7. The method for forming an optical device according to claim 1 , wherein etching the substrate to form the first processing region and the second processing region comprises: etching the first process region when a blocking element is present above the second process region; removing the blocking element; as well as The first processing region and the second processing region are etched.

8. The method for forming an optical device according to claim 1, further comprising: forming a hard mask over the grating material; as well as A first set of openings is patterned above the first processing region and a second set of openings is patterned above the second processing region, wherein the grating material is etched through the first and second sets of openings.

9. The method of forming an optical device according to claim 1, wherein the grating material is an optical grating material.

10. A method of forming an optical device, comprising: providing a mask layer atop the substrate, the mask layer comprising a first opening defining a first processing region and a second opening defining a second processing region; Etching the substrate to form the first processed region having a first depth and the second processed region having a second depth different from the first depth; forming an optical grating material on the substrate having the first processing region and the second processing region formed thereon; as well as A plurality of structures are formed by etching a plurality of trenches into the optical grating material in the first and second processed regions, wherein the plurality of structures are oriented at a non-zero angle relative to a perpendicular extending from a top surface of the substrate.

11. The method of forming an optical device according to claim 10, wherein etching the plurality of trenches into the optical grating material comprises performing angled ion implantation to form the first plurality of trenches and the second plurality of trenches. 12 . The method of forming an optical device of claim 11 , further comprising varying a trench depth between two or more trenches in the first plurality of trenches, and varying a trench depth between two or more trenches in the second plurality of trenches.

13. The method of forming an optical device according to claim 10, wherein the plurality of structures comprises a first group of structures and a second group of structures.

14. The method of forming an optical device of claim 13, wherein the first set of structures has a first average structure width, wherein the second set of structures has a second average structure width, and wherein the first average structure width is different from the second average structure width. 15 . The method for forming an optical device according to claim 10 , wherein the mask layer further comprises a third opening defining a third processing region.

16. The method for forming an optical device according to claim 10, wherein etching the substrate to form the first processing region and the second processing region comprises: forming a barrier element above the second processing region; etching the first processing region when the blocking element is present above the second processing region; removing the blocking element; as well as The first processing region and the second processing region are etched.

17. The method for forming an optical device according to claim 10, further comprising: forming a hard mask over the optical grating material; as well as A first set of openings is patterned above the first processing region and a second set of openings is patterned above the second processing region, wherein the optical grating material is etched through the first and second sets of openings.

18. A method of forming an optical device, comprising: providing an ion beam source within a chamber, wherein the chamber is operable to deliver an ion beam to a substrate, and wherein the substrate includes a first processing region separated from a second processing region by a mask element; etching the substrate to form a first processed region having a first depth and a second processed region having a second depth different from the first depth, wherein the first processed region and the second processed region are recessed to different depths relative to a top surface of the substrate; forming an optical grating material on the substrate having the first processing region and the second processing region formed thereon; as well as A plurality of structures are formed by etching a plurality of trenches into the optical grating material in the first and second processed regions, wherein the plurality of structures are oriented at a non-zero angle relative to a perpendicular extending from the top surface of the substrate.

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