Method for manufacturing an optical device structure

Abstract

To provide methods of forming optical device structures.SOLUTION: Methods disclosed herein utilize rotation of a substrate 101 for having optical device structures 102 formed thereon, and tunability of etching rates of a patterned resist disposed on the substrate and one of a device layer or the substrate to form the optical device structures 102 without multiple lithographic patterning steps and angled etching steps.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001] FIELD OF THE INVENTION

[0001] Embodiments of the present invention generally relate to optical devices for augmented reality, virtual reality, and mixed reality. In particular, embodiments described herein provide for forming blazed optical device structures. [Background technology]

[0002]

[0002] Virtual reality is generally considered to be a computer-generated simulated environment in which a user has an apparent physical presence. The virtual reality experience is generated in 3D and can be viewed using a head-mounted display (HMD), such as glasses or other wearable display devices with near-eye display panels, such as lenses, to display the virtual reality that replaces the real environment.

[0003]

[0003] Augmented reality, however, enables an experience in which a user can still see the surrounding environment through the display lenses of glasses or other HMD devices, and can also see images of virtual objects that are generated for the display and appear as part of the environment. Augmented reality can include any type of input, such as voice input or haptic input, as well as virtual images, graphics, and video that enhance or augment the environment the user experiences. Because augmented reality is an emerging technology, there are many challenges and design constraints.

[0004]

[0004] One such challenge is displaying virtual images overlaid on the surrounding environment. Optical devices, including waveguide couplers such as augmented reality waveguide couplers and planar optical devices such as metasurfaces, are used to help overlay multiple images. Generated light propagates through the optical device until it exits the optical device and is overlaid on the surrounding environment. The optical device may require a structure with a blazed angle relative to the surface of the optical device substrate. Conventionally, multiple lithographic patterning and angled etching steps are required to fabricate blazed optical devices using one or more angled etching tools. The multiple lithographic patterning and angled etching steps increase manufacturing time and increase costs.

[0005]

[0005] Therefore, there is a need in the art for improved methods of forming optical devices, including blazed optical devices, using angled etching tools. Summary of the Invention

[0006] In one embodiment, a method is provided. The method includes positioning a substrate in a path of a beam at a first rotation angle φ1. The beam is configured to project onto the substrate at a beam angle θ relative to a surface normal of the substrate. A patterned resist is formed on the substrate, where the patterned resist includes two or more resist structures and one or more gaps. Each of the resist structures has a width, and each of the gaps is defined by an adjacent resist structure and has a linewidth defined by the adjacent resist structure. The method includes etching the substrate positioned at the first rotation angle φ1 with the beam, rotating the substrate to a second rotation angle φ2, and etching sidewalls of the resist structures directed toward the beam, thereby decreasing the width of the resist structures and increasing the linewidth of the gaps. The method further includes rotating the substrate to the first rotation angle φ1, etching the substrate at the first rotation angle φ1 with the beam, and forming two or more optical device structures in the substrate. Forming the optical device structure includes repeating the steps of rotating the substrate to a second rotation angle φ2, etching the sidewalls of the resist structure using the beam, rotating the substrate to a first rotation angle φ1, and etching the substrate using the beam until the resist structure is removed or the line width of the gap has a predetermined line width.

[0007] In another embodiment, a method is provided. The method includes positioning a substrate in a path of a beam at a first rotation angle φ1. The beam is configured to project onto the substrate surface at a beam angle θ relative to a surface normal of the substrate. A device layer is formed on the substrate, and a patterned resist is formed on the device layer. The patterned resist includes two or more resist structures and one or more gaps. Each of the resist structures has a width, and each of the gaps is defined by an adjacent resist structure and has a linewidth defined by the adjacent resist structure. The method includes etching the device layer with the beam while the substrate is positioned at the first rotation angle φ1, rotating the substrate to a second rotation angle φ2, and etching sidewalls of the resist structures directed toward the beam, thereby decreasing the widths of the resist structures and increasing the linewidths of the gaps. The method further includes rotating the substrate to a first rotation angle φ1, etching the device layer at the first rotation angle φ1 with the beam, and forming two or more optical device structures in the device layer. Forming the optical device structures includes repeating rotating the substrate to a second rotation angle φ2, etching sidewalls of the resist structures with the beam, rotating the substrate to the first rotation angle φ1, and etching the device layer with the beam until the resist structures are removed or the linewidth of the gap has a predetermined linewidth.

[0008] In yet another embodiment, a method is provided. The method includes positioning a substrate in a path of a beam at a first rotation angle φ1. The beam is configured to project onto the substrate surface at a beam angle θ relative to a surface normal of the substrate. A patterned resist is formed on the substrate, where the patterned resist includes two or more resist structures and one or more gaps. Each of the resist structures has a width, and each gap is defined by an adjacent resist structure and has a linewidth defined by the adjacent resist structures. The substrate is etched with a beam generated by a substrate etching chemistry, and the resist structures are etched with a beam generated by a resist etching chemistry different from the substrate etching chemistry. The method further includes etching the substrate positioned at the first rotation angle φ1 with a beam generated by the substrate etching chemistry, rotating the substrate to a second rotation angle φ2, and etching sidewalls of the resist structures with the beam at the beam angle θ. The beam generated by the resist etching chemistry etches the sidewalls of the resist structures directed toward the beam. The method further includes rotating the substrate to a first rotation angle φ1, etching the substrate at the first rotation angle φ1 with a beam generated by the substrate etching chemistry, and forming two or more optical devices in the substrate. Forming the optical device structures includes repeating the steps of rotating the substrate to a second rotation angle φ2, etching sidewalls of the resist structures with a beam generated by the resist etching chemistry, rotating the substrate to the first rotation angle φ1, and etching the substrate with a beam generated by the substrate etching chemistry until the resist structures are removed or the linewidth of the gap has a predetermined linewidth.

[0009]

[0009] So that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the present disclosure briefly summarized above will be rendered by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only exemplary embodiments and therefore should not be considered as limiting the scope thereof, which may permit other equally effective embodiments. [Brief explanation of the drawings]

[0010] [Figure 1A]

[0010] FIG. 1 is a perspective front view of an optical device according to several embodiments described herein. [Figure 1B]

[0011] 1B and 1C are schematic cross-sectional views of device structures according to embodiments described herein. [Figure 1C] 1B and 1C are schematic cross-sectional views of device structures according to embodiments described herein. [Figure 2]

[0012] FIG. 1 is a schematic side view of a tilted etching system according to several embodiments described herein. [Figure 3]

[0013] 1 is a schematic cross-sectional view of a tilted etching system according to several embodiments described herein. [Figure 4]

[0014] FIG. 1 is a flow diagram of a method for forming blazed device structures of an optical device structure according to embodiments described herein. [Figure 5A]

[0015] 5A-5E are schematic cross-sectional views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5B] 5A-5E are schematic cross-sectional views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5C]5A-5E are schematic cross-sectional views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5D] 5A-5E are schematic cross-sectional views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5E] 5A-5E are schematic cross-sectional views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5F]

[0016] 5F-5J are schematic top views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5G] 5F-5J are schematic top views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5H] 5F-5J are schematic top views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5I] 5F-5J are schematic top views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. [Figure 5J] 5F-5J are schematic top views of a portion of a substrate during a method for forming multiple blazed device structures according to multiple embodiments described herein. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0017] For ease of understanding, where possible, like reference numerals have been used to designate like elements common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further description.

[0012]

[0018] Embodiments of the present invention generally relate to optical devices for augmented reality, virtual reality, and mixed reality. In particular, embodiments described herein provide a method for forming a blazed optical device structure that utilizes rotation of a substrate having an optical device structure formed thereon and the ability to adjust the etch rate of a patterned resist disposed on the substrate and one of the device layer or the substrate to form the optical device structure without multiple lithographic patterning and angled etching steps.

[0013]

[0019] In one embodiment, a method includes positioning a substrate at a first rotation angle φ1 in a path of a beam, the beam being configured to be projected onto a surface of the substrate at a beam angle θ relative to a surface normal of the substrate. The substrate has patterned resist formed thereon. The patterned resist includes two or more resist structures. Each of the resist structures has a width and one or more gaps. Each of the gaps is defined by an adjacent resist structure and has a linewidth defined by the adjacent resist structures. The substrate positioned at the first rotation angle φ1 is etched using the beam. The substrate is rotated to a second rotation angle φ2, and sidewalls of the resist structures are etched using the beam at the beam angle θ, thereby decreasing the width of the resist structures and increasing the linewidth of the gaps. The substrate is rotated to the first rotation angle φ1, and the substrate is etched using the beam at the first rotation angle φ1. Two or more optical device structures are formed in the substrate. Forming the optical device structure includes repeating the steps of rotating the substrate to a second rotation angle φ2, etching the sidewalls of the resist structure using the beam, rotating the substrate to a first rotation angle φ1, and etching the substrate using the beam until the resist structure is removed or the line width of the gap has a predetermined line width.

[0014]

[0020] FIG. 1A shows a perspective front view of an optical device 100. It should be understood that the optical device 100 described below is an exemplary optical device. In one embodiment, which may be combined with other embodiments described herein, the optical device 100 is a waveguide coupler, such as an augmented reality waveguide coupler. In another embodiment, which may be combined with other embodiments described herein, the optical device 100 is a planar optical device, such as a metasurface. The optical device 100 includes a plurality of device structures 102 disposed within (as shown in FIG. 1B) or on (as shown in FIG. 1C) a substrate 101. As shown in FIG. 1C, the device structures 102 are formed within a device layer 114 formed on the substrate 101. The device structures 102 may be nanostructures having submicron dimensions, e.g., nano-sized dimensions, such as critical dimensions of less than 1 μm. In one embodiment that can be combined with other embodiments described herein, regions of device structure 102 correspond to one or more diffraction gratings 104, such as first diffraction grating 104a, second diffraction grating 104b, and third diffraction grating 104c. In one embodiment that can be combined with other embodiments described herein, optical device 100 is a waveguide coupler that includes at least first diffraction grating 104a corresponding to an input coupling grating and third diffraction grating 104c corresponding to an output coupling grating. A waveguide coupler according to an embodiment that can be combined with other embodiments described herein may include second diffraction grating 104b corresponding to an intermediate diffraction grating.

[0015]

[0021] 1B and 1C are schematic cross-sectional views of multiple device structures 102. In one embodiment that may be combined with other embodiments described herein, the device structure 102 is a blazed optical device 106, which is a planar optical device such as a metasurface. A method 400 described herein forms the blazed optical device 106. In another embodiment that may be combined with other embodiments described herein, the device structure 102 is a blazed optical device structure 106 of a waveguide coupler, such as an augmented reality waveguide coupler. A waveguide coupler according to one embodiment that may be combined with other embodiments described herein may include the blazed optical device structure 106 within at least one of the diffraction gratings 104. Each of the blazed device structures 106 includes a blazed surface 108, a sidewall 112, a depth h, and a linewidth d. The blazed surface 108 has a plurality of steps 110. In one embodiment, which may be combined with other embodiments described herein, the blazed surface 108 includes at least 16 steps 110, e.g., more than 32 steps 110, e.g., 64 steps 110. The blazed surface 108 has a blaze angle γ. The blaze angle γ is the angle between the blazed surface 108 and a surface parallel line p of the substrate 101, and is the angle between the surface normal of the substrate 101 and a facet normal f of the blazed surface 108. The depth h corresponds to the height of the sidewalls 112, and the linewidth d corresponds to the distance between the sidewalls 112 of adjacent blazed structures 106.

[0016]

[0022] In one embodiment that may be combined with other embodiments described herein, the blaze angles γ of two or more blazed device structures 106 are different. In another embodiment that may be combined with other embodiments described herein, the blaze angles γ of two or more blazed device structures 106 are the same. In one embodiment that may be combined with other embodiments described herein, the depths h of two or more blazed device structures 106 are different. In another embodiment that may be combined with other embodiments described herein, the depths h of two or more blazed device structures 106 are the same. In one embodiment that may be combined with other embodiments described herein, the linewidths d of two or more blazed device structures 106 are different. In another embodiment that may be combined with other embodiments described herein, the linewidths d of two or more blazed device structures 106 are the same.

[0017]

[0023] Substrate 101 may also be selected to transmit an appropriate amount of light at a desired wavelength or wavelength range, such as one or more wavelengths from about 100 to about 3000 nanometers. In some non-limiting embodiments, substrate 101 is configured to transmit about 50% to about 100% or more of the IR to UV region of the light spectrum. Substrate 101 may be formed from any suitable material, provided that substrate 101 can adequately transmit light at a desired wavelength or wavelength range and serve as a suitable support for blazed device structure 106 described herein (when blazed device structure 106 is formed in device layer 114). Substrate choices may include, but are not limited to, substrates of any suitable material, such as amorphous dielectrics, non-amorphous dielectrics, crystalline dielectrics, silicon oxides, polymers, and combinations thereof. In some embodiments, which may be combined with other embodiments described herein, substrate 101 comprises a transparent material. Suitable examples may include oxides, sulfides, phosphides, tellurides, or combinations thereof. In one embodiment, the substrate 101 comprises a high-index transparent material such as silicon (Si), silicon dioxide (SiO 2 ), germanium (Ge), silicon germanium (SiGe), sapphire, and high-index glass.

[0018]

[0024] In some embodiments, which may be combined with other embodiments described herein, the device layer 114 may be formed of any material, including, but not limited to, silicon oxycarbide (SiOC), titanium dioxide (TiO), silicon dioxide (SiO), vanadium(IV) oxide (VO x), aluminum oxide (Al2O3), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO2), zinc oxide (ZnO), tantalum pentoxide (Ta2O5), silicon nitride (Si3N4), zirconium dioxide (ZrO2), niobium oxide (Nb2O5), cadmium stannate (Cd2SnO4), or silicon carbonitride (SiCN)-containing materials. In some embodiments that may be combined with other embodiments described herein, the material of the device layer 114 may have a refractive index between about 1.5 and about 2.65. In other embodiments that may be combined with other embodiments described herein, the material of the device layer 114 may have a refractive index between about 3.5 and about 4.0.

[0019]

[0025] 2 is a schematic side view of an angled etching system 200. It should be understood that the angled etching system 200 described below is an exemplary angled etching system, and that other angled etching systems may be used or modified to fabricate optical devices 100 having blazed device structures 106 according to embodiments of the present disclosure.

[0020]

[0026] The angled etching system 200 includes an ion beam chamber 202. A power supply 204, a first gas source 206, and a second gas source are coupled to the ion beam chamber 202. In one embodiment, which may be combined with other embodiments described herein, the power supply 204 is a radio frequency (RF) power supply. The first gas source 206 is in fluid communication with an interior space 205 of the ion beam chamber 202. The first gas source 206 is an inert gas source that supplies an inert gas, such as argon, hydrogen, or helium, to the ion beam chamber 202. The second gas source 208 is in fluid communication with the interior space 205 of the ion beam chamber 202. The second gas source 208 is a process gas source that supplies a process gas to the ion beam chamber 202. The process gas may include, but is not limited to, one or more of a chlorine-containing gas, a fluorine-containing gas, a bromine-containing gas, an oxygen-containing gas, a silicon-containing gas, a nitrogen-containing gas, a hydrogen-containing gas, or the like. In embodiments of the method 400 described herein, which may be combined with other embodiments described herein, more than one process gas may be utilized.

[0021]

[0027] The first process gas may have a substrate etch chemistry that is selective to resist materials. The etch selectivity of the first process gas having the substrate etch chemistry provides a selectivity between the substrate material and the resist material (described below) of about 5:1 or greater. The etch selectivity of the first process gas having the device material etch chemistry provides a selectivity between the device material and the resist material of about 5:1 or greater. In one embodiment, which may be combined with other embodiments described herein, the substrate etch chemistry includes a chlorine-containing gas, a fluorine-containing gas, or a combination thereof. In another embodiment, which may be combined with other embodiments described herein, the device material etch chemistry includes a chlorine-containing gas, a fluorine-containing gas, or a combination thereof.

[0022]

[0028] The second process gas may have a resist etch chemistry that is selective to the substrate material or the device material. The etch selectivity of the second process gas having the resist material etch chemistry provides a resist material to substrate material selectivity of about 10:1 or greater, or a resist material to device material selectivity of about 10:1 or greater. In one embodiment that may be combined with other embodiments described herein, the resist etch chemistry includes oxygen gas (O) and carbon tetrafluoride (CF). In another embodiment that may be combined with other embodiments described herein, the resist etch chemistry includes argon gas (Ar), nitrogen gas (N), and hydrogen gas (H). In yet another embodiment that may be combined with other embodiments described herein, the resist etch chemistry includes nitrogen gas (N) and hydrogen gas (H).

[0023]

[0029] In operation, a plasma is generated in the ion beam chamber 202 by applying RF power via a power source 204 to an inert gas and a process gas provided into the interior volume 205 of the ion beam chamber 202 to generate a plasma. Ions of the plasma of the inert gas and the process gas are extracted through an aperture 210 in an extraction plate 212 to generate an ion beam 216. The aperture 210 of the ion beam chamber 202 is operable to direct the ion beam 216 at an angle α with respect to a reference plane 218 oriented perpendicular (i.e., surface normal) to the substrate 101. The ion beam 216 includes, but is not limited to, a spot beam, a ribbon beam, or a full-substrate-sized beam. The generated ion beam 216 includes one of a substrate etch chemistry, a device material etch chemistry, or a resist etch chemistry, depending on the process gases utilized.

[0024]

[0030] The substrate 101 is held on a platen 214 coupled to a first actuator 219. The first actuator 219, which may be a linear actuator, a rotary actuator, a stepper motor, or the like, is configured to move the platen 214 in a scanning motion along the y and / or z directions. In one embodiment, which may be combined with other embodiments described herein, the first actuator 219 is further configured to tilt the platen 214 such that the substrate 101 is positioned at a tilt angle β relative to the x-axis of the ion beam chamber 202. The angle α and the tilt angle β result in a beam angle θ relative to a reference plane 218 that is normal to the substrate 101. A second actuator 220, which may also be coupled to the platen 214, rotates the substrate 101 about the x-axis of the platen 214.

[0025]

[0031] 3 is a schematic cross-sectional view of an angled etching system 300. It should be understood that the angled etching system 300 described below is an exemplary angled etching system, and that other angled etching systems may be used or modified to fabricate optical devices 100 having blazed device structures 106 according to embodiments of the present disclosure.

[0026]

[0032] The angled etching system 300 includes an electron beam chamber 302. A power supply 304, a first gas source 306, and a second gas source 308 are coupled to the electron beam chamber 302. The first gas source 306 and the second gas source 308 are in fluid communication with an interior space 305 of the electron beam chamber 302. For example, the first gas source 306 and the second gas source 308 may extend through an electrode 322, or the electrode 322 may include a plurality of apertures to function as a gas distribution showerhead. The first gas source 306 is an inert gas source that supplies an inert gas (as described above) to the electron beam chamber 302. The second gas source 308 is a process gas source (as described above) that supplies a process gas to the electron beam chamber 302. More than one process gas may be utilized in embodiments of the method 400 described herein, which may be combined with other embodiments described herein. The two or more process gases include a substrate etch chemistry, a device material etch chemistry, and a resist etch chemistry as described herein.

[0027]

[0033] The substrate 101 is held on a platen 314 coupled to a first actuator 321. The first actuator 321, which may be a linear actuator, a rotary actuator, a stepper motor, or the like, is configured to raise and lower the platen 314 within the electron beam chamber 302. A second actuator 320 may also be coupled to the platen 314 and rotates the substrate 101 about a vertical axis of the platen 314. The platen 314 includes an electrode 324 disposed therein. In one embodiment, the electrode 324 is a chucking device, such as an electrostatic chuck, for securing the substrate 101 to the electrode 324 during processing of the substrate 101. Power from the power supply 304 may be utilized to bias the electrode 324 to either chuck the substrate 101 to the electrode 324 or to influence the bombardment of electrons onto the substrate 101.

[0028]

[0034] In operation, a plasma is generated within the electron beam chamber 302 by various bulk and surface processes, for example by inductive coupling. Ions generated by an inductively coupled plasma are believed to be influenced by an electric field that encourages ions generated from the plasma of the inert gas and process gas to collide with the electrode 322. Other plasma generation processes, such as capacitively coupled configurations, hollow cathode configurations, DC electrode biasing, or electron beam plasma generation processes, may be utilized in accordance with embodiments described herein.

[0029]

[0035] Ion bombardment of the electrode 322 is believed to cause the electrode 322 to emit secondary electrons. Negatively charged, energetic secondary electrons are emitted from the electrode 322. Thus, the electron beam 316 is accelerated from the electrode 322 at a beam angle θ relative to a reference plane 318 oriented perpendicular (i.e., surface normal) to the substrate 101. The electron beam 316 includes, but is not limited to, a spot beam, a ribbon beam, or a full-substrate-sized beam. The generated electron beam 316 includes one of a substrate etch chemistry, a device material etch chemistry, or a resist etch chemistry, depending on the process gases utilized.

[0030]

[0036] As described herein, the ion beam 216 generated from the angled etching system 200 (e.g., an ion etching system) and the electron beam 316 generated from the angled etching system 300 (e.g., an electron beam etching system) are collectively referred to as beam 516 (as shown in FIGS. 5A-5J ). In this case, beam 516 is one of an ion beam or an electron beam. In some embodiments of method 400 that may be combined with other described embodiments, beam 516 has one of a substrate etch chemistry, a device material etch chemistry, or a resist etch chemistry in the operations of method 400 described herein. In some embodiments that may be combined with other embodiments described herein, at least the substrate etch chemistry and the resist etch chemistry are different. In other embodiments that may be combined with other embodiments described herein, at least the device material etch chemistry and the resist etch chemistry are different. As described herein, the ability to adjust the etch rate of the resist material 506 and one of the device layer 114 or the substrate 101, and rotation of the substrate 101, forms blazed optical device structures without multiple lithographic patterning and etching steps.

[0031]

[0037] 4 is a flow diagram of a method 400 for forming a plurality of blazed optical device structures 106 of optical device structure 100, as shown in FIGS. 5A-5E and 5F-5J. FIGS. 5A-5E are schematic side views of a portion 501 of substrate 101 during method 400. FIGS. 5F-5J are schematic top views of a portion 501 of substrate 101 during method 400.

[0032]

[0038] For ease of explanation, method 400 will be described with reference to angled etching system 200 of FIG. 2 and angled etching system 300 of FIG. 3 . However, it should be noted that angled etching systems other than angled etching systems 200 and 300 may also be utilized in conjunction with method 400. In one embodiment that may be combined with other embodiments described herein, portion 501 may correspond to a portion or the entire surface of substrate 101 of a planar optical device having a plurality of blazed optical device structures 106 formed thereon. In another embodiment that may be combined with other embodiments described herein, portion 501 may correspond to a portion or the entire surface of substrate 101 of a waveguide coupler having a plurality of blazed optical device structures 106 formed thereon. Portion 501 may correspond to one or more diffraction gratings 104. Although Figures 5A-5E and 5F-5J depict etching substrate 101 so that blazed optical device structure 106 is disposed within the substrate, device layer 114 may also be disposed on surface 103 (as described above) so that blazed optical device structure 106 is disposed within device layer 114.

[0033]

[0039] In operation 401, as shown in FIGS. 5A and 5F , substrate 101 is positioned at a first rotation angle φ1 as defined by reference line 502, as shown in FIG. 5F . In one embodiment, which may be combined with other embodiments described herein, first rotation angle φ1 is 0 degrees as defined by reference line 502. Substrate 101 or device layer 114 (not shown) includes patterned resist 504 disposed thereon. Patterned resist 504 includes resist material 506 patterned into a plurality of resist structures 508 disposed on surface 103 of substrate 101. Resist material 506 of patterned resist 504 is selected based on a substrate etch chemistry (in embodiments in which substrate 101 is etched to form blazed optical device structures 106) or a device material etch chemistry (in embodiments in which device material layer 114 is etched to form blazed optical device structures 106). In one embodiment, resist material 506 is a photosensitive material. The patterned resist 504 may thereby be patterned by a lithography process, such as photolithography or digital lithography, or by a laser ablation process, to form a plurality of resist structures 508. In one embodiment, the resist material 506 is an imprintable material. The patterned resist 504 may thereby be patterned by a nanoimprint process, to form a plurality of resist structures 508. In another embodiment that may be combined with other embodiments described herein, the resist material 506 is a hard mask material, and the patterned resist 504 may be patterned via one or more etching processes, to form a plurality of resist structures 508. In yet another embodiment that may be combined with other embodiments described herein, the patterned resist 504 is an optical planarization layer.

[0034]

[0040] Each resist structure 508 includes a lower surface 509, a first sidewall 510, a second sidewall 512, and a top surface 514. Each resist structure 508 has a height 515 from the lower surface 509 to the top surface 514. Each resist structure 508 has a width 522 from the first sidewall 510 to the second sidewall 512 of the resist structure 508. A plurality of gaps 518 are defined by adjacent resist structures 508. Each gap 518 has a linewidth 520 between the first sidewall 510 and the second sidewall 512 of the adjacent resist structure 508. The height 515, linewidth 520, and width 522 are selected to adjust the number of steps 110 and linewidth d of the blazed surface 108 of the plurality of blazed device structures 106. For example, increasing height 515 increases the number of repeating intervals that etch substrate 101 (or device layer 114) and resist structure 508, thereby increasing the number of steps 110.

[0035]

[0041] In operation 402, substrate 101 is exposed to beam 516 at a beam angle θ relative to a surface normal of substrate 101. In one embodiment, which may be combined with other embodiments described herein, beam angle θ is from about 10 degrees to about 80 degrees relative to a surface normal of substrate 101. Beam 516 has a substrate etch chemistry or a device etch chemistry that is selective to resist material 506. That is, exposed portions 517 of substrate 101 or exposed portions of device layer 114 (not shown) are removed at a higher rate than resist material 506. After beam 516 etches the exposed portions of substrate 101, operation 402 (as shown in FIG. 5B ) forms exposed portions 517 of substrate 101 that correspond to blazed device structures 106.

[0036]

[0042] In operation 403, as shown in FIG. 5H , the substrate 101 is rotated to a second rotation angle φ2 defined by the reference line 502. In an embodiment that may be combined with other embodiments described herein, the platen 214, 314 holding the substrate 101 is rotated to the second rotation angle φ2. In another embodiment that may be combined with other embodiments described herein, the second rotation angle φ2 corresponds to 90 degrees with respect to the reference line 502. The rotation of the substrate 101 is not limited to a rotation angle φ corresponding to 90 degrees, but may correspond to any predetermined angle φ. This rotation allows the beam 516 to contact the resist structure 508 due to a shadowing effect. In an embodiment that may be combined with other embodiments described herein, the beam 516 remains at a beam angle θ with respect to the reference surface 218, 318, which is oriented perpendicular (i.e., surface normal) to the substrate 101, throughout the method 400. A constant beam angle may improve throughput. This is because there is no need to reset the beam angle θ. In one embodiment, which may be combined with other embodiments described herein, the method 400 described herein uses only one angled etching system 200, 300 and requires patterning the resist material 506 only once, providing mass production capabilities.

[0037]

[0043] In operation 404, the resist structure is exposed to a beam 516 at a beam angle θ. The beam 516 etches either the first sidewall 510 or the second sidewall 512, depending on which sidewall 510, 512 is exposed to the beam 516. In one embodiment, which may be combined with other embodiments described herein, the first sidewall 510 is exposed to the beam 516. The beam 516 has a chemistry that corresponds to the resist etch chemistry, such that the ions or electrons substantially etch only the resist structure 508 during the resist etch process. The resist etch chemistry is selective to the substrate 101 or the device layer 114. That is, the resist structure 508 is removed at a higher rate than the device layer 114 or the substrate 101. After the beam 516 etches the resist structure 508, the width 522 of the resist structure 508 is reduced relative to the width shown in FIGS. 5A and 5B. The line width 520 between the first sidewall and the second sidewall is increased relative to the line width shown in Figures 5A and 5B.

[0038]

[0044] As shown in FIG. 5C , a first step of the plurality of steps 110 is formed. The plurality of steps 110 form the blazed surface 108 shown in FIGS. 1B and 1C . The blaze angle γ is the angle between the blazed surface 108 and a surface parallel line p of the substrate 101. The blaze angle γ may be achieved by increasing or decreasing the etching rate of the beam 516. Adjusting the blaze angle γ may be achieved by etching at different rates, thereby achieving predetermined values ​​for the depth h, linewidth 520, and width 522 corresponding to different numbers of steps 110 formed on the blazed surface 108. Thus, the blazed angle γ may be adjusted so that the blazed device structure 106, such as the blazed device structure 106 of the diffraction grating 104, modulates light propagating through the optical device 100 as desired.

[0039]

[0045] In operation 405, operations 401-404 are repeated until a predetermined number of steps 110 (as shown in FIGS. 1B and 1C) are formed on optical device 100. In one embodiment, which may be combined with other embodiments described herein, substrate 101 is rotated to a first rotation angle φ1, and beam 516 is used to etch substrate 101 or device layer 114 until resist structures 508 are removed or gaps 518 have a predetermined linewidth 520. As shown in FIG. 5I, platen 214, 314 upon which substrate 101 is positioned is rotated to a first rotation angle φ1. As shown in FIG. 5, the depth h of exposed portion 517 corresponding to blazed device structure 106 increases relative to the depth h shown in FIGS. 5A-5C. As shown in FIG. 5J, platen 214, 314 upon which substrate 101 is positioned is rotated to a second rotation angle φ2 defined by reference line 502. After the beam 516 etches the resist structures 508, the width 522 of the resist structures 508 decreases relative to the width shown in Figures 5A-5D. The linewidth 520 between the first sidewall 510 and the second sidewall 512 increases relative to the linewidth 520 shown in Figures 5A-5D. In optional operation 406, any remaining resist material 506 disposed on the device layer 114 or substrate 101 is removed. Although only four resist structures 508 and three gaps 518 are shown, the entire patterned resist 504 may be etched. A desired number of blazed device structures 106 are thereby formed according to a predetermined design for the optical device 100.

[0040]

[0046] In summary, a method for forming an optical device structure is described herein. The method utilizes rotation of a substrate having a blazed optical device structure formed thereon and the ability to adjust the etch rate of a patterned resist disposed on the substrate and one of the device layer or the substrate to form the optical device structure without multiple lithographic patterning and angled etching steps. A constant beam angle can improve throughput because there is no need to reset the beam angle θ. Only one angled etching system can be used, and the resist material needs to be patterned only once, which can provide mass production capabilities.

[0041]

[0047] While the forgoing description is directed to multiple embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, the scope of which is defined by the claims that follow.

Claims

1. an optical device substrate comprising a substrate material; an input coupling grating disposed over the optical device substrate, the input coupling grating comprising a device material different from the substrate material, the input coupling grating having a plurality of blazed device structures, each blazed device structure of the plurality of blazed device structures comprising a blazed surface, the blazed surface comprising: a plurality of steps, each of the blazed device structures having a top surface wider than each of the steps; a facet normal perpendicular to the blazed surface; and a blaze angle between a surface normal of the optical device substrate and the facet normal; an input coupling grating having an out-coupling grating including the device material disposed on the optical device substrate and adjacent to the input-coupling grating, the out-coupling grating having a plurality of device structures; 1. An augmented reality waveguide coupler comprising:

2. The augmented reality waveguide coupler of claim 1 , wherein the blazed surface has at least 32 steps.

3. The augmented reality waveguide coupler of claim 1 , wherein the blazed surface has at least 64 steps.

4. The augmented reality waveguide coupler of claim 1 , wherein the blaze angles of two blazed device structures of the plurality of blazed device structures are different.

5. The augmented reality waveguide coupler of claim 1 , wherein the blaze angles of two blazed device structures of the plurality of blazed device structures are the same.

6. The augmented reality waveguide coupler of claim 1 , wherein two blazed device structures of the plurality of blazed device structures have different depths.

7. The device materials of the in-coupling grating are silicon oxycarbide (SiOC), titanium dioxide (TiO ２ ), silicon dioxide (SiO ２ ), vanadium (IV) oxide (VOx), aluminum oxide (Al ２ O ３ ), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO ２ ), zinc oxide (ZnO), tantalum pentoxide (Ta ２ O ５ ), silicon nitride (Si ３ N ４ ), zirconium dioxide (ZrO ２ ), niobium oxide (Nb ２ O ５ ), cadmium stannate (Cd ２ SnO ４ ), or silicon carbonitride (SiCN)-containing materials.

8. The augmented reality waveguide coupler of claim 1 , wherein the substrate material of the optical device substrate comprises a non-amorphous dielectric, a crystalline dielectric, silicon oxide, a polymer, or a combination thereof.

9. The substrate material of the optical device substrate is silicon (Si), silicon dioxide (SiO ２ ), germanium (Ge), silicon germanium (SiGe), sapphire, or a combination thereof.

10. The augmented reality waveguide coupler of claim 1 , wherein the optical device substrate is configured to transmit wavelengths between 100 and 3000 nanometers.

11. The augmented reality waveguide coupler of claim 1 , wherein each blazed device structure of the plurality of blazed device structures has a refractive index between 1.5 and 2.

65.

12. The augmented reality waveguide coupler of claim 1 , wherein each blazed device structure of the plurality of blazed device structures has a refractive index between 3.5 and 4.

0.

13. an optical device substrate comprising a substrate material; an input coupling grating disposed over the optical device substrate, the input coupling grating comprising a device material different from the substrate material, the input coupling grating having a plurality of blazed device structures, each blazed device structure of the plurality of blazed device structures comprising a blazed surface, the blazed surface comprising: a plurality of steps, each of the blazed device structures having a top surface wider than each of the steps; a facet normal perpendicular to the blazed surface; and a blaze angle between a surface normal of the optical device substrate and the facet normal, the blaze angle of two blazed device structures of the plurality of blazed device structures being different; an input coupling grating having an out-coupling grating including the device material disposed on the optical device substrate and adjacent to the input-coupling grating, the out-coupling grating having a plurality of device structures; 1. An augmented reality waveguide coupler comprising:

14. The augmented reality waveguide coupler of claim 13 , wherein the two blazed device structures of the plurality of blazed device structures have different depths.

15. The device materials of the in-coupling grating are silicon oxycarbide (SiOC), titanium dioxide (TiO ２ ), silicon dioxide (SiO ２ ), vanadium (IV) oxide (VOx), aluminum oxide (Al ２ O ３ ), aluminum-doped zinc oxide (AZO), indium tin oxide (ITO), tin dioxide (SnO ２ ), zinc oxide (ZnO), tantalum pentoxide (Ta ２ O ５ ), silicon nitride (Si ３ N ４ ), zirconium dioxide (ZrO ２ ), niobium oxide (Nb ２ O ５ ), cadmium stannate (Cd ２ SnO ４ 14. The augmented reality waveguide coupler of claim 13, comprising one or more of: silicon dioxide (SiO2), silicon carbide (SiO2), or silicon carbonitride (SiCN) containing materials.

16. The augmented reality waveguide coupler of claim 13 , wherein the substrate material of the optical device substrate comprises a non-amorphous dielectric, a crystalline dielectric, silicon oxide, a polymer, or a combination thereof.

17. The substrate material of the optical device substrate is silicon (Si), silicon dioxide (SiO ２ 14. The augmented reality waveguide coupler of claim 13, comprising: germanium (Ge), silicon germanium (SiGe), sapphire, or a combination thereof.

18. The augmented reality waveguide coupler of claim 13 , wherein the optical device substrate is configured to transmit wavelengths between 100 and 3000 nanometers.

19. The augmented reality waveguide coupler of claim 13 , wherein each blazed device structure of the plurality of blazed device structures has a refractive index between 1.5 and 2.

65.

20. an optical device substrate comprising a substrate material and configured to transmit wavelengths between 100 and 3000 nanometers; an input coupling grating disposed over the optical device substrate, the input coupling grating comprising a device material different from the substrate material, the input coupling grating having a plurality of blazed device structures, each blazed device structure of the plurality of blazed device structures having a refractive index between 1.5 and 2.65 and comprising a blazed surface, the blazed surface comprising: a plurality of steps, each of the blazed device structures having a top surface wider than each of the steps; a facet normal perpendicular to the blazed surface; and a blaze angle between a surface normal of the optical device substrate and the facet normal, the blaze angle of two blazed device structures of the plurality of blazed device structures being different; an input coupling grating having an out-coupling grating including the device material disposed on the optical device substrate and adjacent to the input-coupling grating, the out-coupling grating having a plurality of device structures; 1. An augmented reality waveguide coupler comprising:

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