Etching improvement

Abstract

A method is provided. The method includes exposing a first material disposed on a first plane of a first substrate to an ion beam to form a first plurality of structures in the first material, the ion beam directed to the first material at an ion beam angle θ relative to a surface normal of the first substrate. The first substrate is positioned at a first angle of rotation φ1 between the ion beam and a first vector of the first plurality of structures, the first material is incrementally exposed to the ion beam along a first direction, and the exposure of the first material to the ion beam is varied along the first direction to produce a depth variation between the first plurality of structures in the first direction.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to angled etch tools. More specifically, embodiments described herein relate to forming structures of optical devices using angled etch tools. BACKGROUND

[0002] To form structures having different tilt angles, such as fins of one or more gratings, on a substrate, an angled etch system can be used. One example of an angled etch system is an ion beam chamber housing an ion beam source. The ion beam source is configured to generate an ion beam, such as a ribbon beam, a spot beam, or a full substrate size beam. The ion beam chamber is configured to direct the ion beam at an angle relative to a surface normal of the substrate to produce structures having a particular tilt angle. Changing the tilt angle of the structures produced by the ion beam requires substantial hardware reconfiguration of the ion beam chamber.

[0003] Optical devices can include different structures having different tilt angles. Therefore, to form an optical device including different structures having different tilt angles, a large amount of hardware reconfiguration is required. Furthermore, manufacturing an optical device having structures with different tilt angles compared to a previously manufactured optical device encounters similar problems.

[0004] Conventionally, a time-consuming and complex process has been used to form optical devices including different structures having different depths across a surface of a substrate, which adds a considerable cost to any device manufactured using this process.

[0005] Therefore, there is a need for improved methods and related devices to form optical devices including structures having different depths (or different depths and different tilt angles) across a substrate on a single substrate, and to form optical devices including structures having different depths (or different depths and different tilt angles) on consecutive substrates. SUMMARY

[0006] Embodiments of the present disclosure generally relate to angled etch tools. In one embodiment, a method is provided. The method includes exposing a first material disposed across a first plane on a first substrate to an ion beam to form a first plurality of structures in the first material, the ion beam directed to the first material at an ion beam angle Θ relative to a surface normal of the first substrate, wherein: the first substrate is positioned at a first rotation angle φ1 between the ion beam and a first vector of the first plurality of structures, the first vector extending across the first plane in a direction normal to the first plurality of structures, the first material is incrementally exposed to the ion beam along the first direction, and the exposure of the first material to the ion beam varies along the first direction to produce a depth variation among the first plurality of structures in the first direction.

[0007] In another embodiment, a method is provided. The method includes: exposing a first material disposed on a substrate across a first plane to an ion beam during a first time period to form a first plurality of structures in the first material, the ion beam directed to the first material at an ion beam angle Θ relative to a surface normal of the substrate, wherein the substrate is disposed at a first rotation angle φ1 between the ion beam and a first vector of the first plurality of structures during the first time period, the first vector extending across the first plane perpendicular to a direction of the first plurality of structures; and exposing the disposed first material to the ion beam during a second time period, wherein the substrate is disposed at a second rotation angle φ2 between the ion beam and the first vector of the first plurality of structures during the second time period.

[0008] In another embodiment, a method is provided. The method includes: exposing a first material disposed on a substrate across a first plane to an ion beam during a first time period to form a first plurality of structures in the first material, the ion beam directed to the first material at an ion beam angle Θ relative to a surface normal of the substrate, wherein the substrate is positioned at a first rotation angle φ1 between the ion beam and a first vector of the first plurality of structures during the first time period, the first vector extending across the first plane orthogonal to a direction of the first plurality of structures, the first plurality of structures formed to have a first tilt angle Θ1' relative to the surface normal of the substrate during the first time period, and the first rotation angle φ1 is selected by an equation φ1 = cos -1 (tan(θ1') / tan(θ)) during the first time period; and exposing the first material to the ion beam during a second time period, wherein the substrate is positioned at a second rotation angle φ2 between the ion beam and the first vector of the first plurality of structures during the second time period, wherein the second rotation angle φ2 is a negative angle of the first rotation angle φ1, a duty cycle for generating the ion beam is varied according to a first profile during the first time period, and the duty cycle for generating the ion beam is varied according to a second profile during the second time period. BRIEF DESCRIPTION OF DRAWINGS

[0009] So that the above-recited features of the present disclosure can be understood in more detail, a more particular description of the disclosure, briefly summarized above, can be had by reference to the embodiments thereof that are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only example embodiments and therefore are not to be considered as limiting its scope, and that the embodiments can admit to other equally effective embodiments.

[0010] Figure 1 is a perspective front view of an optical device according to one embodiment.

[0011] Figure 2A is a side schematic cross-sectional view of an angled etching system according to one embodiment.

[0012] Figure 2B is a top view schematic cross-sectional view of an angled etch system in accordance with one embodiment. Figure 2A is a top view schematic cross-sectional view of an angled etch system in accordance with one embodiment.

[0013] Figure 3 is a schematic perspective view of a portion of a substrate in accordance with one embodiment.

[0014] Figure 4 is a plot of the results of an equivalent tilt angle equation in accordance with one embodiment.

[0015] Figure 5 is a schematic top view of a substrate having a first portion of structures and a second portion of structures in accordance with one embodiment.

[0016] Figure 6 is a plot of the results of a system of equations for a rotation angle phi 1, a rotation angle phi 2, and an ion beam angle theta in accordance with one embodiment.

[0017] Figure 7 is a flow chart of a method for forming structures having different tilt angles in accordance with one embodiment.

[0018] Figure 8 is a flow chart of a method for forming portions of structures having different tilt angles in a single pass in accordance with one embodiment.

[0019] Figure 9A is a top view of a contour plot of a device including structures in accordance with one embodiment, where the depth between structures varies in one dimension.

[0020] Figure 9B shows how the duty cycle of an ion beam can vary in the Z direction according to a duty cycle profile across a device to produce the depth variation shown in the contour plot of Figure 9A in accordance with one embodiment.

[0021] Figure 9C is a partial side view cross-sectional view of a device shown in Figure 9A in accordance with one embodiment.

[0022] Figure 10 is a process flow chart of a method for forming structures shown in Figures 9A-9C in accordance with one embodiment.

[0023] Figure 11A is a top view of a contour plot of a device including structures in accordance with one embodiment, where the depth between structures varies in multiple dimensions.

[0024] Figure 11Bis a top view of a contour plot of a device according to one embodiment, showing the depth variation between structures resulting from exposure of a first material of the device to an ion beam while the device is positioned at a first angle of rotation.

[0025] Figure 11C is a top view of a contour plot of a device according to one embodiment, showing the depth variation between structures resulting from exposure of a first material of the device to an ion beam while the device is positioned at a second angle of rotation.

[0026] Figure 11D is a plot showing how the duty cycle of an ion beam according to one embodiment can vary across a device to produce the depth variation between structures shown in the contour plots of Figure 11B , 11C .

[0027] Figure 12 is a process flow diagram for a method for forming a device shown in Figure 11A according to one embodiment.

[0028] To facilitate an understanding of this description, like reference characters are used to identify like elements throughout the figures. It is intended that elements of one embodiment can be beneficially incorporated into other embodiments without further recitation.

[0029] Embodiments

[0030] Embodiments described herein relate to methods for forming optical devices including structures having different depths (or different depths and different tilt angles) across a single substrate, and forming optical devices including structures having different depths (or different depths and different tilt angles) on successive substrates. Although described below in large part with reference to performing one or more etches to form one or more gratings of an optical device (e.g., a waveguide combiner), the following disclosure can be applied to any process that uses one or more etches. For example, the following disclosure can be applied to any etch in which structures are formed having one or more specified tilt angles and / or one or more specified depths.

[0031] Figure 1This is a perspective front view of an optical device 100 according to one embodiment. Examples of the optical device 100 include, but are not limited to, planar optics and waveguides (e.g., waveguide combiners). The optical device 100 includes one or more gratings. In one embodiment, which can 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, and 106 includes a corresponding structure 108, 110, 112 (e.g., a fin). In one embodiment, which can be combined with other embodiments described herein, the structures 108, 110, 112, and the depth between the structures, include submicron critical dimensions (e.g., nanometer critical dimensions).

[0032] Figure 2A This is a schematic cross-sectional side view of the angled etching system 200. Figure 2B This is a schematic top cross-sectional view of an angled etching system 200, such as the Varian etch system available from Applied Materials, Inc. in Santa Clara, California, USA. System. It should be understood that the angled etching system 200 described below is an exemplary angled etching system, and other angled etching systems, including angled etching systems from other manufacturers, can be used or modified to form the structures described herein on a substrate.

[0033] Figure 2A and Figure 2B A device 205 disposed on a platform 206 is shown. Device 205 includes a substrate 210, an etch stop layer 211 disposed above the substrate 210, a grating material 212 disposed on the etch stop layer 211 spanning a first plane (YZ plane), and a hard mask 213 disposed on the grating material 212. A structure with an angled tilt (e.g., fin) is formed, and the grating material 212 is etched by an angled etch system 200. In one embodiment, the grating material 212 is disposed on the etch stop layer 211, which is disposed on the substrate 210, and a patterned hard mask 213 is disposed on the grating material 212. In one embodiment, one or more materials of the grating material 212 are selected based on the tilt angle θ' of each structure to be formed and the refractive index of the substrate 210. In some embodiments, the grating material 212 includes one or more materials containing: silicon oxycarbide (SiOC), titanium dioxide (TiO2), silicon dioxide (SiO2), vanadium oxide (IV) (VO2). xaluminum oxide (AI2O3), 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 an index of refraction between about 1.5 and about 2.65. The example provided above for the grating material 212 applies to materials used in forming optical devices, such as the device 205. More generally, the grating material 212 (also referred to as the "first material") is not limited to the materials listed above, but can be any etchable material. For example, as noted at the outset of this specification, the subject matter of the present disclosure is not limited to applications related to forming optical devices, such as the optical device 205, and thus the use of the term "first material" is more generally referring to a material that can be preferentially etched (e.g., by an ion beam) relative to another material (e.g., a hard mask layer).

[0034] In some embodiments, the patterned hard mask 213 is an opaque hard mask that is removed after forming the device 205. For example, the non-transparent hard mask can include a reflective material, such as chromium (Cr) or silver (Ag). In another embodiment, the patterned hard mask 213 is a transparent hard mask. In one embodiment, the etch stop layer 211 is an opaque etch stop layer that is removed after forming the device 205. In another embodiment, the etch stop layer 211 is a transparent etch stop layer.

[0035] The angled etching system 200 includes an ion beam chamber 202 that houses an ion beam source 204. The ion beam source is configured to generate an ion beam 216, such as a ribbon beam, a spot beam, or a full substrate size beam. As described below, the ion beam chamber 202 is configured to direct the ion beam 216 at a first ion beam angle a relative to a surface normal 218 of the substrate 210 before the substrate 210 is tilted. Changing the first ion beam angle a requires reconfiguring hardware of the ion beam chamber 202. The substrate 210 is held on a platform 206 that is connected to a first actuator 208. The first actuator 208 is configured to move the platform 206 in a scan motion along the y-direction and / or the z-direction. In one embodiment, the first actuator 208 is further configured to tilt the platform 206 such that the substrate 210 is positioned at a tilt angle b relative to the x-axis of the ion beam chamber 202 (e.g., rotated about the Y-axis). In some embodiments, the first actuator 208 can be further configured to tilt the platform 206 relative to the y-axis and / or the z-axis.

[0036] After the substrate 210 is tilted, the first ion beam angle a and the tilt angle b result in a second ion beam angle Q relative to the surface normal 218 of the substrate 210. To form a structure having a tilt angle Q' relative to the surface normal 218, the ion beam source 204 generates the ion beam 216 and the ion beam chamber 202 directs the ion beam 216 toward the substrate 210 at the first ion beam angle a. The first actuator 208 positions the platform 206 so that the ion beam 216 contacts the grating material 212 at the second ion beam angle Q and etches the grating material 212 to form the structure having the tilt angle Q' on the desired portion of the grating material 212.

[0037] Conventionally, to form a portion of a structure at a tilt angle Q' different than the tilt angle Q' of an adjacent structure portion, or to form structures having different tilt angles Q' on a continuous substrate, the first ion beam angle a is changed, the tilt angle b 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 a is complex and time consuming. Adjusting the tilt angle b to modify the ion beam angle Q results in non-uniform depths of the structures on various portions of the substrate 210 as the ion beam 216 contacts the grating material 212 at different energy levels. For example, portions closer to the ion beam chamber 202 will have structures with greater depths than adjacent portions further from the ion beam chamber 202. Using multiple angled etching systems increases manufacturing time and cost due to the need for multiple chambers. To avoid reconfiguring the ion beam chamber 202, adjusting the tilt angle b to change the ion beam angle Q, and using multiple angled etching systems, the angled etching system 200 includes a second actuator 220 connected to the platform 206 to rotate the substrate 210 along the x-axis of the platform 206 to control the tilt angle Q' of the structure.

[0038] Figure 3is a schematic perspective view of a portion 300 of a substrate 302 according to one embodiment. The tilt angle β and the first ion beam angle a of the ion beam 216 are fixed such that the ion beam angle θ relative to the surface normal 306 of the substrate 302 is constant across the substrate 302. The first ion beam angle a is between about 0° and about 90°, and the tilt angle β is between about 0° and about 30°. The resulting second ion beam angle θ is between about 0° and about 90°. The second ion beam angle θ is preferably between about 25° and about 75°, as ion beam angles θ close to about 0° or close to about 90° would result in structures 304 having a tilt angle θ' of about 0° or about 90°, such that the structures 304 are not tilted. The substrate 302 is rotated about the x-axis of the stage 206, resulting in a rotation angle φ between the ion beam 216 and the grating vector 308 of the structures 304. The rotation angle φ is selected to control the tilt angle θ' without reconfiguring the ion beam chamber 202, without adjusting the tilt angle β to change the ion beam angle θ, and without using multiple angled etching systems. To determine the final tilt angle θ' from the second ion beam angle θ, the following equivalent tilt angle θ' equations are used: sin(θ') = sin(θ) / sqrt(l + tan 2 (φ)*cos 2 (θ)) and tan(θ') = tan(θ)*cos(φ). Solving for φ, the rotation angle φ is cos -1 (tan(θ') / tan(θ)). For example, if the ion beam angle θ is 45°, and the desired tilt angle θ' is 22.5°, then the rotation angle φ is about 65.53°, i.e., cos -1 (tan(22.5) / tan(45)) = 65.53. Figure 4 is a graph of the results of the equivalent tilt angle θ' equations as a function of the rotation angle φ for ion beam angles θ of 5°, 22.5°, 45°, 67.5°, and 85°.

[0039] The grating vector 308 can also be more generally referred to as a first vector. As noted above, the present invention is not limited to applications related to forming optical devices such as the optical device 205, and thus the use of the term "first vector" is more generally a reference to a vector in the direction normal to the plane across which a first plurality of structures extends, with the material to be etched (e.g., the grating material 212) disposed in this plane. For example, the grating material (also referred to as a first material) is disposed across a YZ plane (also referred to as a first plane), and the grating vector 308 (also referred to as a first vector) is normal to the direction in which the structures 304 extend in the YZ plane. Reference is made to Figure 2A and Figure 3 , the structures 304 are spaced apart in a direction substantially close to the Z direction, and the structures extend in a direction substantially close to the Y direction.

[0040] In one embodiment, structures 304 having a tilt angle θ' can be formed using an angled etching system 200 as shown in FIGS. 1-3. In another embodiment, structures 304 having a tilt angle θ' can be formed using an ion beam etching system (also referred to as a full wafer, immersion, or mesh etching system) having an ion beam source 204 housed in an ion beam chamber 202 that generates an ion beam 216 having a geometry corresponding to the geometry of the surface of the substrate 302 at a first ion beam angle a of about 0°. A stage 206 of the ion beam etching system is configured to position the substrate 210 at a tilt angle β such that the ion beam 216 contacts the substrate 302 at an ion beam angle θ of between about 25° and about 75°. The rotation angle φ is selected to control the tilt angle θ' as described herein. Figure 2A , Figure 2B In one embodiment, structures 304 having a tilt angle θ' can be formed using an angled etching system 200 as shown in FIGS. 1-3. In another embodiment, structures 304 having a tilt angle θ' can be formed using an ion beam etching system (also referred to as a full wafer, immersion, or mesh etching system) having an ion beam source 204 housed in an ion beam chamber 202 that generates an ion beam 216 having a geometry corresponding to the geometry of the surface of the substrate 302 at a first ion beam angle a of about 0°. A stage 206 of the ion beam etching system is configured to position the substrate 210 at a tilt angle β such that the ion beam 216 contacts the substrate 302 at an ion beam angle θ of between about 25° and about 75°. The rotation angle φ is selected to control the tilt angle θ' as described herein.

[0041] Figure 5 is a schematic top view of a substrate 500 having a first portion 502 of structures 506 and a second portion 504 of structures 508 according to one embodiment. In one embodiment, the portions 502, 504 can be a first grating 502 and a second grating 504, and the structures 506, 508 can be respective fins 506, 508 of the gratings 502, 504. The structures 506, 508 can be formed using the angled etching system 200 shown in FIGS. 1-3 above. Figure 2A , Figure 2B Figure 2A , Figure 2B Figure 5 Figure 5 The tilt angle β and the first ion beam angle a of the ion beam 216 are fixed such that the ion beam angle θ relative to a surface normal of the substrate 500 is constant when the ion beam 216 is directed to the different portions 502, 504. The first ion beam angle a is between about 0° and about 90°, and the tilt angle β is between about 0° and about 30°. The resulting second ion beam angle θ is between about 0° and about 90°. The second ion beam angle θ is preferably between about 25° and about 75°, as ion beam angles θ close to about 0° or close to about 90° would result in structures having a tilt angle of about 0° or about 90°, such that the structures 506, 508 are not tilted.

[0042] ​​​To form the structures 506, 508 of the respective portions 502, 504, the substrate 500 can be rotated about the x-axis of the stage 206, resulting in a rotation angle φ1 between the ion beam 216 and the grating vector 510 of the structure 506 for forming the structure 506, and a rotation angle φ2 between the ion beam 216 and the grating vector 512 of the structure 508 for forming the structure 508. The pattern of the hard mask in a particular region can be used to determine the grating vector of this region, as the pattern of the hard mask determines the direction in which the structure extends across the substrate after etching is performed. For example, the grating vector 510 (also referred to as a first vector) is substantially perpendicular to the direction in which the structure 506 extends in the YZ plane (also referred to as a first plane). Similarly, the grating vector 512 (also referred to as a second vector) is substantially perpendicular to the direction in which the structure 508 extends in the YZ plane (also referred to as a first plane).

[0043] By moving the stage 206 in a scan motion that passes through the ion beam chamber 202 in a single pass such that the first portion 502 and the second portion 504 are positioned in the path of the ion beam 216, the rotation angle φ1 is selected to form the structure 506 having a tilt angle θ'1, and the rotation angle φ2 is selected to form the structure 508 having a tilt angle θ'2. To form two or more portions of a structure (e.g., the structures 506, 508) in a single pass of the stage 206 through the ion beam chamber 202, the following equations are implemented:

[0044] θ = arctan(tan(θ'1) / cos(φ1))

[0045] θ = arctan(tan(θ'2) / cos(φ2))

[0046] Δφ = φ2 - φ1

[0047] In one embodiment, the tilt angle θ'1, the tilt angle θ'2, and the Δφ are known. Solving the system of equations for the rotation angle φ1, the rotation angle φ2, and the ion beam angle θ will allow the structure 506 having the tilt angle θ'1 and the structure 508 having the tilt angle θ'2 to be formed in a single pass of the stage 206 through the ion beam chamber 202.

[0048] Figure 6is a plot that is a result of a system of equations for the rotation angle φ1, the rotation angle φ2, and the ion beam angle θ. To form the structure 506 with a tilt angle θ'1 of 40° and the structure 508 with a tilt angle θ'2 of 20° at a Δφ of 45°, a rotation angle φ1 of 21.1° and a rotation angle φ2 of 66.1° will form the first portion 502 and the second portion 504 at a single pass of the stage 206 through the ion beam chamber 202. Thus, the structure 506 with the tilt angle θ'1 and the structure 508 with the tilt angle θ'2 are formed at a single pass of the stage 206 through the ion beam chamber 202 without reconfiguring the ion beam chamber 202, without adjusting the tilt angle β to modify the ion beam angle θ, and without using multiple angled etching systems. Additionally, the system of equations can be extended to form three or more portions of a structure (e.g., a grating) with different tilt angles θ'. In another embodiment, the ion beam angle θ, the tilt angle θ'1, the tilt angle θ'2, and the Δφ are known, and the system of equations is solved for the rotation angle φ1 and the rotation angle φ2.

[0049] Figure 7 is a flowchart of a method 700 for forming a structure with different tilt angles. In one embodiment, the method 700 is performed by the angled etching system 200 shown above in Figure 2A 、 Figure 2B . The method 700 is described with reference to Figure 2A 、 Figure 2B and Figure 7 . The angled etching system 200 includes an ion beam source 204 housed in an ion beam chamber 202, the ion beam source 204 generating an ion beam 216, such as a ribbon beam or a spot beam. The ion beam chamber 202 is configured to direct the ion beam 216 at a first ion beam angle a relative to a surface normal 218 of a substrate 210. A first actuator 208 connected to a stage 206 is configured to move the substrate 210 in a scan motion and tilt the stage 206 such that the substrate 210 is positioned at a tilt angle β relative to an axis of the ion beam chamber 202. The first actuator 208 is configured to move the stage 206 in the scan motion along a y-direction and / or a z-direction. The first ion beam angle a and the tilt angle β result in a second ion beam angle θ relative to the surface normal 218.

[0050] At operation 701, a first portion of a first substrate having a grating material 212 disposed therein is positioned in a path of an ion beam 216. The ion beam 216 contacts the grating material 212 at an ion beam angle θ relative to a surface normal 218 of the first substrate and forms one or more first structures in the grating material 212. The first substrate is held on a stage 206. The stage 206 is configured to position the first portion of the first substrate in the path of the ion beam 216 and to rotate the first substrate about an axis of the stage 206, thereby producing a first rotation angle φ between the ion beam 216 and a grating vector (e.g., grating vector 308) of the one or more first structures. The first rotation angle φ is selected to cause the one or more first structures to have a first tilt angle θ’ relative to the surface normal 218 of the substrate. As described above, the first rotation angle φ is selected by the rotation angle φ equation φ = cos -1 (tan(θ’) / tan(θ)). In one embodiment, the first portion can correspond to an input grating 102 of an optical device 100 as shown. Figure 1

[0051] To form one or more second structures having a second tilt angle θ’ different from the first tilt angle θ’ on a second portion of the first substrate without reconfiguring the ion beam chamber 202 to change the first ion beam angle a, adjusting the tilt angle β to change the ion beam angle θ, or using multiple angled etching systems, the first ion beam angle a and the tilt angle β remain constant while the first substrate is rotated about the axis of the stage 206 by a second actuator 220 connected to the stage 206.

[0052] At operation 702, a second portion of the first substrate having the grating material 212 disposed therein is positioned in the path of the ion beam 216. The ion beam 216 contacts the grating material 212 at the ion beam angle θ relative to the surface normal 218 of the first substrate and forms the one or more second structures in the grating material 212. The second portion is positioned in the path of the ion beam 216 with the first substrate rotated about the axis of the stage 206, thereby producing a second rotation angle φ between the ion beam 216 and a grating vector (e.g., grating vector 308) of the one or more second structures. The second rotation angle φ is selected to cause the one or more second structures to have a second tilt angle θ’ relative to the surface normal 218 of the substrate. The second rotation angle φ is selected by the rotation angle φ equation φ = cos -1 (tan(θ’) / tan(θ)). In one embodiment, the second portion can correspond to an intermediate grating 104 of an optical device 100 as shown. Figure 1

[0053] ​​At operation 703, a third portion of the first substrate having the grating material 212 disposed thereon is positioned in the path of the ion beam 216. The ion beam 216 contacts the grating material 212 at an ion beam angle θ with respect to a surface normal 218 of the first substrate and forms one or more third structures in the grating material 212. The third portion is positioned in the path of the ion beam 216 and the first substrate is rotated about an axis of the stage 206, resulting in a third rotation angle φ between the ion beam 216 and a grating vector (e.g., grating vector 308) of the one or more third structures. The third rotation angle φ is selected to cause the one or more third structures to have a third tilt angle θ' with respect to the surface normal 218 of the substrate. The third rotation angle φ is selected by the rotation angle φ equation φ = cos -1 (tan(θ') / tan(θ)). In one embodiment, the third portion can correspond to the output grating 106 of the optical device 100 shown in FIG. 1. Figure 1

[0054] At operation 704, the first substrate is removed and a second substrate is held on the stage 206. At operation 705, operations 701-703 are repeated to form one or more first structures having a first tilt angle θ', one or more second structures having a second tilt angle θ' different from the first tilt angle θ', and one or more third structures having a third tilt angle θ' different from the first tilt angle θ' and the second tilt angle θ' on the second substrate.

[0055] Figure 8 is a flowchart of a method 800 for forming portions of structures having different tilt angles according to one embodiment. In one embodiment, the method 800 is performed by the angled etching system 200 shown in FIGS. 2-4 above. Reference is made to the description of the angled etching system 200 shown in FIGS. 2-4 above for a detailed description of the method 800. Figure 2A 2B Figure 2A Figure 2B Figure 5 Figure 8 ​​​​​​The method 800 is described with reference to FIG. 8. In operation 801, a first portion 502 and a second portion 504 of a substrate 500 having a grating material 212 disposed thereon are positioned in a path of an ion beam 216 with the platform 206 single pass through the ion beam chamber 202. The ion beam 216 contacts the grating material 212 at an ion beam angle Θ relative to a surface normal 218 of the substrate 500 and forms one or more structures 506 and one or more structures 508 in the grating material 212. The substrate 500 remains on the platform 206, which is configured to position the first portion 502 and the second portion 504 in the path of the ion beam 216 with the substrate 500 rotating about an axis of the platform 206, thereby creating a rotation angle φ1 between the ion beam 216 and a grating vector 510 of the one or more structures 506 and a rotation angle φ2 between the ion beam 216 and a grating vector 512 of the one or more structures 508. The rotation angle φ1 is selected to cause the one or more structures 506 to have a tilt angle Θ'1 relative to the surface normal 218 of the substrate. The rotation angle φ2 is selected to cause the one or more structures 508 to have a tilt angle Θ'2 relative to the surface normal 218 of the substrate. The rotation angle φ1 and the rotation angle φ2 are selected by solving a system of equations:

[0056] Θ = arctan(tan(Θ'1) / cos(φ1))

[0057] Θ = arctan(tan(Θ'2) / cos(φ2))

[0058] Δφ = φ2 - φ1

[0059] In one embodiment, the tilt angle Θ'1, the tilt angle Θ'2, and the Δφ are known. Solving the system of equations for the rotation angle φ1, the rotation angle φ2, and the ion beam angle Θ will allow the formation of the structures 506 having the tilt angle Θ'1 and the structures 508 having the tilt angle Θ'2 with the platform 206 single pass through the ion beam chamber 202. In another embodiment, the ion beam angle Θ, the tilt angle Θ'1, the tilt angle Θ'2, and the Δφ are known and the system of equations is solved for the rotation angle φ1 and the rotation angle φ2. Thus, the structures 506 having the tilt angle Θ'1 and the structures 508 having the tilt angle Θ'2 are formed with the platform 206 single pass through the ion beam chamber 202 without the need to reconfigure the ion beam chamber 202, without the need to adjust the tilt angle β to modify the ion beam angle Θ, and without the need to use multiple angled etching systems. Additionally, the system of equations can be extended to form three or more portions of a grating. The method 800 can be repeated for subsequent substrates.

[0060] The above describes methods of using an angled etching system to form structures (e.g., fins of a grating) with different tilt angles on a single substrate in succession and to form structures (e.g., fins of a grating) with different tilt angles on successive substrates. Selecting one or more rotation angles φ to control the tilt angle θ' of the formed structures without reconfiguring the ion beam chamber, adjusting the tilt angle β to change the ion beam angle θ, or using multiple angled etching systems allows for the use of a single angled etching system (e.g., the angled etching system 200 shown in Figure 2A , Figure 2B to manufacture optical devices (e.g., waveguide combiners) with structures having different tilt angles θ' and different optical devices (e.g., different waveguide combiners) containing different structures.

[0061] The angled etching system 200 or similar systems can also be used to create structures with features that differ from those shown in Figure 2A , Figure 2B , Figure 3 For example, structures shown in Figure 2A are formed so that the area between the structures across the device (e.g., in the YZ plane) has the same depth in the X direction. In some applications, the depth between the structures in the X direction can vary in one or more directions across the device (i.e., in the YZ plane). The depth between the structures can be varied, for example, to control the percentage of light coupled through one or more gratings (e.g., a set of gratings used on a waveguide combiner). A shallower depth between the structures in a grating results in weaker coupling of light through the grating, while a deeper depth between the structures in a grating results in stronger coupling of light through the grating. Controlling the percentage of light coupled through a set of gratings improves control over an image that is ultimately displayed to a user of the waveguide combiner, for example, through an augmented reality device.

[0062] Creating structures (e.g., fins of a grating) with a depth between the structures that varies across the device in one or more dimensions previously required the use of much more complex processes than the processes described below. Embodiments of the processes described below are used to form devices containing structures with a depth between the structures that varies in one dimension (see Figures 9A-9C and Figure 10 and to form devices containing structures with a depth between the structures that varies in multiple dimensions (see Figures 11A-11D and Figure 12 ). These devices containing structures with varying depths between the structures described below can be formed by the angled etching system 200 described above, for example, with reference to Figure 2A .

[0063] Figure 9Ais a top view of an isometric plot 940 of a device 900 including structures according to one embodiment, where the depth between structures varies in one dimension. The device including structures and the depth between structures varies in one dimension (e.g., Z in Figure 9A Figure 9A The device including structures and the depth between structures varies in one dimension (e.g., Z in Figure 9A Figure 9A The device including structures and the depth between structures varies in one dimension (e.g., Z in

[0064] In Figure 9A , the device 900 will be rotated at a first angle of rotation φ1. The device 900 can be formed by the angled etching system 200 described above. The device 900 includes a plurality of structures (e.g., fins of one or more gratings), where the depth between structures varies along the Z direction. As described above, the tilt angle θ’ of the structures can be determined in part by the first angle of rotation φ1, and will be described in further detail below. The depth shadow plot 930 indicates how the depth between structures varies across the device 900, as shown in the isometric plot 940. Referring to the depth plot 930, the isometric plot 940 shows that the depth between structures varies from a maximum depth in the first section 911 at the center in the Z direction to a decreasing depth in the top sections 9121-9171 and the bottom sections 9122-9172 in the opposite Z direction. For example, the depth between structures decreases (i.e., gets shallower) with each section from the first section 911 to the top seventh section 9171. Similarly, the depth between structures decreases (i.e., gets shallower) with each section from the first section 911 to the bottom seventh section 9172. Although the isometric plot 940 shown in Figure 9A shows sections with different discrete depths and a constant shadow in each section, the depths of these sections can gradually vary between adjacent sections (and within a section). For example, the depth in the top second section 9121 can gradually decrease toward the decreasing depth in the top third section 9131, and the depth in the top third section 9131 can gradually decrease toward the depth in the top fourth section 9141, and so on. In some embodiments, the ion beam 216 can be translated in the Z direction to produce the variation in the depth between structures shown in Figure 9A . In other embodiments, the device 900 can be translated in the Z direction to expose different sections of the device 900 to the ion beam 216.

[0065] ​​Device 900 also includes two segments 9201 and 9202 in which no material is removed. In some embodiments, segments 9201 and 9202 are not exposed to the angled ion beam 216 of the etching system 200. In other embodiments, segments 9201 and 9202 may be covered by a hard mask or other material that is not significantly affected by the ion beam 216. Other embodiments may have more or fewer segments that are not modified by the ion beam 216.

[0066] Figure 9B Figure 950 illustrates how the duty cycle of an ion beam 216 according to one embodiment can vary in the Z direction according to a duty cycle profile 951 on device 900 to produce Figure 9A The contour plot 940 shows the depth variation. For example, duty cycle profile 951 shows how the duty cycle of the ion beam 216 gradually increases from a low duty cycle of about 0.1 at the -100Z position to a high duty cycle of about 0.8 at the zeroZ position, and then gradually decreases to a low duty cycle of about 0.1 at the +100Z position. Although duty cycle profile 951 shows a duty cycle modified similar to a Gaussian distribution, other methods can be used to change the duty cycle across the entire device 900 to generate different depth profiles across the entire device. Furthermore, other methods can be used to modify the depth across the entire device 900. For example, in other embodiments, the time for which the ion beam 216 is focused on different portions of the device 900 can be varied in the Z direction while using a constant duty cycle. In other embodiments, the power (e.g., voltage and / or current) applied to generate the ion beam 216 can be varied in the Z direction to produce… Figure 9A The depth variation in the Z direction is shown in the diagram.

[0067] Figure 9C According to one implementation method Figure 9A A partial side cross-sectional view of device 900 shown. Device 900 is similar to... Figure 2A , Figure 2B The device 205 shown differs from device 900 in that it has a different structure. Device 900 includes a substrate 210, an etch stop layer 211, a grating material 212, and a hard mask 213. The substrate is disposed on a platform 206. Trench 905 is formed in the grating material 212 disposed above the substrate 210. Structures 906 (e.g., fins) are disposed between the trenches 905. The etch stop layer 211 is disposed between the grating material 212 and the substrate 210. The hard mask 213 is disposed above the grating material 212.

[0068] In device 900, trenches 905 (i.e., the regions between structures 906) have depths that vary in the Z-direction. For example, as shown, the depths of trenches 905 and the corresponding heights of structures 906 increase in the Z-direction from left to right on the page. For example, second trench 9052 has a greater depth than first trench 9051, and second structure 9062 has a greater height than first structure 9061. In some embodiments, the depths of trenches 905 and the heights of structures 906 can vary in the Z-direction for each grating. For example, as shown, for each trench 905, the depth of the trench 905 gradually increases from first trench 9051 to fifth trench 9055. Similarly, for each structure 906, the height of the structure 906 gradually increases from first structure 9061 to fifth structure 9065. The depths of different trenches 905 in the Z-direction and the heights of structures 906 can be caused to increase by increasing the duty cycle of ion beam 216 as different portions of grating material 212 are exposed to ion beam 216 in the Z-direction.

[0069] Trenches 905 are each aligned at an oblique angle θ'. In some embodiments, each trench 905 is formed by a first surface 901 and an opposing second surface 902 of an adjacent structure 906 that is aligned at oblique angle θ'. In other embodiments, each trench 905 is formed by a first surface 901 and an opposing second surface 902 of an adjacent structure 906 that is substantially aligned (e.g., within about 5 degrees of oblique angle θ' or within about 1 degree of oblique angle θ') at oblique angle θ'. In embodiments where the angles of surfaces 901, 902 differ from one another, oblique angle θ' can be an average between the angles of surfaces 901, 902. Oblique angle θ' can have a value from about 0° to about 90°, such as from about 15° to about 75°. In embodiments where the structures are aligned or substantially aligned according to oblique angle θ', the structures can be described as being formed to have oblique angle θ'.

[0070] Trenches 905 can be formed by directing ion beam 216 of angled etching system 200 Figure 2A ) at a second ion beam angle θ while substrate 210 is disposed in a position in which device 900 is rotated to a rotation angle φ1 Figure 9A ) along an axis of device 900 (i.e., an axis that extends in the X-direction through the center of device 900). Rotation angle φ1 -1 at which device 900 is disposed in angle equation φ1 = cos Figure 9A ) can be selected by the rotation angle equation φ1 = cos Figure 2AThe second ion beam angle θ is based on the first ion beam angle α relative to the surface normal 218 of the substrate 210 and the tilt angle β relative to the x-axis of the ion beam chamber 202. Adjusting the first ion beam angle α and / or the tilt angle β causes the problems described above, and therefore these angles can be avoided when structures with different tilt angles (e.g., structure 906) are produced by adjusting the rotation angle (e.g., rotation angle φ1) instead. Therefore, by inputting the values ​​of the second ion beam angle θ and the desired tilt angle θ' into the rotation angle equation, the rotation angle φ1 used to produce a structure with a given tilt angle θ' can be obtained.

[0071] The rotation angle φ1 is 216 for the ion beam (see...). Figure 2A ) and grating vector (e.g. Figure 3 The angle between the grating vector 308 and the structure 304 shown. The grating vector can be perpendicular to the direction in which the structure extends (e.g., in the direction of the structure's extension). Figure 3 (Extending in the YZ plane). For example, from Figure 3 The grating vector 308 of A is perpendicular to the direction in which structure 304 extends in the YZ plane. The grating vector can also be in the same plane as the direction in which the structure extends. For example, the grating vector 308 is in the same plane as the direction in which structure 304 extends (i.e., a plane parallel to the top surface of the substrate). Therefore, the rotation angle φ1, determined by the given second ion beam angle θ and the desired tilt angle θ', determines how the substrate is rotated relative to the grating vector of the grating or other structure formed by the ion beam 216. Before performing etching to form a structure such as structure 906, the pattern of the hard mask can be used to determine the grating vector for a given portion of the substrate.

[0072] In some implementations, the grating vector can be aligned with the notch 907 (see...). Figure 9A In these embodiments, the substrate can be rotated relative to the notch 907 by a rotation angle φ1. In other embodiments, the grating vector is offset from the notch 907. In these embodiments, this offset is taken into account together with the rotation angle determined from the rotation angle equation to determine how far the substrate is rotated to form a structure with a desired tilt angle θ'.

[0073] Figure 10 It is according to one embodiment for forming Figures 9A-9C The flowchart illustrates the processing of method 1000 for the trench 905 and structure 906 (the first plurality of structures). (Refer to...) Figure 2A , Figure 3 , Figures 9A-9C and Figure 10 Description method 1000.

[0074] In frame 1002, device 900 is positioned at a rotation angle φ1 along the path of ion beam 216 and / or against platform 206. (See above reference.) Figures 9A to 9CThe rotation angle φ1may be determined from the rotation angle equation. In some embodiments, the notch 907 or another feature can be used to align the device 900 to be positioned at the rotation angle φ1.

[0075] At block 1004, while the substrate 210 is positioned at a rotation angle φ1between the ion beam 216 and a grating vector (e.g., grating vector 308) (also referred to as a first vector), the ion beam 216 is applied to expose the grating material 212 (first material) disposed across a YZ plane (first plane) to the ion beam 216 at a second ion beam angle Θ relative to a surface normal 218 of the substrate 210 to form trenches 905 and corresponding structures 906 in the grating material 212. The grating vector (e.g., grating vector 308) (first vector) extends perpendicular to the first plurality of structures across a direction of the YZ plane (first plane). The trenches 905 and structures 906 are formed to have a tilt angle Θ' relative to the surface normal 218 of the substrate 210. In one embodiment, the ion beam 216 can be initially directed to the bottom seventh segment 9172, e.g., aligned with the -100Z position. Figure 9A

[0076] At block 1006, the ion beam 216 can be incrementally directed to different portions of the device 900. For example, the ion beam 216 can be incrementally exposed to the grating material 212 (first material) of the bottom segments 9172-9122 of the device 900, followed by the center first segment 911, and then the top segments 9121-9171. The duty cycle of the ion beam 216 can vary as shown in the duty cycle profile 951 to produce the structures 906 and trenches 905 between the structures 906 that vary according to the contour plot 940. Figure 9B Figure 9A In some embodiments, the ion beam 216 can be scanned in the Z direction according to the varying duty cycle of the duty cycle profile 951 across the device 900, which can be disposed on the fixed stage 206. In other embodiments, the device 900 can be translated in the Z direction to expose different segments to the ion beam 216.

[0077] As previously mentioned, while the contour plot 940 is shown with segments having different discrete depths (e.g., 911 and 9121), the duty cycle of the ion beam 216 can vary as Figure 9A The illustrated contour plot 940 shows segments (e.g., 911 and 9121) having different discrete depths, but the duty cycle of the ion beam 216 can vary as Figure 9B ​​The depth between structures 906 in a segment can gradually change between adjacent segments (and within a segment) as shown by the duty cycle profile 951 in FIG. 9B. As also noted above, varying the duty cycle of the ion beam 216 is only one way to vary the depth of the trenches 905 between structures 906 in the Z direction. For example, in other embodiments, the time that the ion beam 216 is focused on different segments of the device 900 can vary in the Z direction and a constant duty cycle can be used to form structures with a depth between structures that varies in the Z direction. In other embodiments, the power (e.g., voltage and / or current) applied to generate the ion beam 216 can vary in the Z direction to generate Figure 9A the depth variation in the Z direction shown in FIG. 9B.

[0078] After block 1006, the method 1000 can be repeated to process other substrates with the same structures or different structures, such as structures with different tilt angles and / or structures with different depth variation profiles. To process another substrate to have structures formed with different tilt angles, a new rotation angle (f2) can be determined based on the new tilt angle (Q2') according to the rotation angle equation, and the method 1000 can be repeated using the newly determined rotation angle (f2) to position the new substrate at block 1002. For example, the first substrate can be removed from the substrate support, and a second substrate can be positioned on the substrate support. When the second substrate is positioned on the substrate support, the second substrate can have a grating material (also referred to as a second material) disposed across a YZ plane (also referred to as a second plane). The second substrate can be positioned at a second rotation angle f2 between the ion beam and grating vectors (second vectors) of a second plurality of structures formed on the second substrate by the ion beam 216. The second vectors extend perpendicular to the direction of the second plurality of structures to be formed across the second plane. Then, as blocks 1004 and 1006 above are repeated, the grating material (second material) on the second substrate can be exposed to the ion beam.

[0079] To process another substrate to have structures formed with the same tilt angle but with different depth profiles of the trenches between the structures, the duty cycle or other processing parameters (e.g., exposure time, power applied to generate the ion beam 216) can be modified at blocks 1004 and 1006 to generate the specified depth profile while the substrate can be positioned at the same position with the rotation angle f1, as previously explained with reference to block 1002 and illustrated in FIG. 9B. Figure 9A Further, a modified version of block 1002 can be combined with the modified versions of blocks 1004, 1006 to process another substrate and generate a device with structures having different tilt angles and structures between the structures having different depth profiles than the structures and trenches formed on the first substrate from the initial execution of blocks 1002-1006.

[0080] Method 1000 can also be performed and repeated on isolated regions of a single substrate to form different structures with different tilt angles and different depth profiles on a single substrate. For example, with reference to Figure 7 and Figure 10 Method 1000 can be performed at operation 701, again at operation 702, and again at operation 703. Operations 701-703 are described above as being used to generate structures with different tilt angles. Thus, performing method 1000 on an isolated region of a single substrate at each of operations 701-703 can be used to form: (1) at block 701, a first plurality of structures extending with a first tilt angle θ1’, where the depth between the first plurality of structures varies according to a first depth profile; (2) at block 702, a second plurality of structures extending with a second tilt angle θ2’, where the depth between the second plurality of structures varies according to a second depth profile; and (3) at block 703, a third plurality of structures extending with a third tilt angle θ3’, where the depth between the third plurality of structures varies according to a third depth profile.

[0081] In some implementations, devices can be formed with structures where the depth between the structures varies in multiple dimensions. Devices with structures and where the depth between the structures varies in multiple dimensions can enhance control of light coupled through the device, such as where the structures are used to form one or more gratings of a waveguide combiner. Such enhanced control of light coupled through a device, such as a waveguide combiner, can further improve the quality of images output from the waveguide combiner to, for example, a user of an augmented reality device that includes the waveguide combiner. Figures 11A-11D and Figure 12 One implementation of a device and related method is described, where the formed device includes structures and where there are trenches between the structures with depth profiles that vary in multiple dimensions.

[0082] Figure 11A is a top view of an isometric view 1140 of a device 1101 including structures (e.g., fins of one or more gratings) where the depth between the structures varies in multiple dimensions, according to one implementation. Device 1101 can extend in the YZ plane and include trenches between the structures with a depth in the X direction, where the depth of the trenches varies in the Y and Z directions. The depth of the trenches between the structures at different locations on device 1101 can be determined with reference to depth map 930, which shows how the relative depth of the trenches between the structures varies on isometric view 1140 of device 1101.

[0083] A device that includes structures and in which the depth between the structures varies in multiple dimensions, as used herein, refers to a device in which there is no single dimension that can be used to describe the direction of the depth variation and there are no dimensions perpendicular to this single dimension for which the depth also varies along them. For example, with reference to Figure 11A there is no dimension along which the depth varies, there are no perpendicular dimensions for which the depth also varies along them. Further, at least in some embodiments, a device that includes structures and in which the depth between the structures varies in multiple dimensions can represent a device that includes a center point C in which the depth varies in directions around the center point C in 360 degrees, as shown in Figure 11A .

[0084] Although not shown separately and not required, the structures of the device 1101 can have similar shapes (e.g., same tilt angle Θ’) as the structures 906 described above with reference to Figure 9C . Further, other features of the device 1101 can be the same as the corresponding features in the device 900 described above. For example, with reference to Figure 9C , the device 1101 can also include a grating material 212 disposed above the substrate 210, where the etch stop layer 211 is disposed between the substrate 210 and the grating material 212, and the hard mask layer 213 is disposed above the grating material 212. The device 1101 can be formed by the angled etching system 200 described above with reference to Figure 2A .

[0085] The device 1101 can be formed to have structures and in which the depth between the structures varies in multiple directions by (1) exposing the grating material 212 of the device 1101 to the ion beam 216 Figure 2A ( Figure 11B ) at a first rotation angle φ1; and subsequently (2) exposing the grating material 212 of the device 1101 to the ion beam 216 Figure 11C .

[0086] Figure 11B is a top view of a contour plot 940 of the device 1101 according to one embodiment, showing the depth variation between the structures, which was produced by exposing the grating material 212 of the device 1101 to the ion beam 216 Figure 2A at a first rotation angle φ1 while the device 1101 was positioned. The contour plot 940 is the same contour plot as the contour plot 930. Figure 9A

[0087] Figure 11C ​This is a top view of a contour plot 1240 of a device 1101 according to one embodiment, showing the depth variation between structures, which is produced by exposing the grating material 212 of the device 1101 to the ion beam 216 when the device 1101 is positioned at a second rotation angle φ2. Figure 2A ). Figure 11B , Figure 11C Contour plots 940 and 1240 each show the depth changes resulting from exposing the previously unexposed grating material 212 to the ion beam 216. Therefore, Figure 11B , Figure 11C Contour plots 940 and 1240 each show the results of depth variations (e.g., trench depths) between structures on device 1101 caused by a single exposure, thus making it easier to understand the individual effects of these individual exposures on depth variations on device 1101. Figure 11A This illustrates the result of depth variations between structures on device 1101, a result generated by producing structures and having according to Figure 11B The elevation view of 940 exposes the depth of the structure between the structures and combines them to produce a structure that is based on Figure 11C The contour map 1240 is generated by exposing the depth between structures. This combined exposure process produces structures where the depth between structures varies in multiple dimensions (i.e., in the Y and Z directions). Figure 12 The flowchart illustrates the exposure handling of this combination in more detail.

[0088] Figure 11D Figure 1150 illustrates how the duty cycle of the ion beam 216, according to one embodiment, can be varied across the entire device 1101 to produce Figure 11B , Figure 11C The depth variations between the structures are shown in contour maps 940 and 1240. This is to generate structures that are based on... Figure 11B The depth variations between structures in contour map 940 can be seen from the previously illustrated diagram. Figure 9B The duty cycle profile 951 in the entire device 1101 is Figure 11B The duty cycle of the ion beam 216 is changed in the Z direction. (See above for reference.) Figure 9A and Figure 9B Additional details relating to the depth variations generated based on contour plot 940 and duty cycle contour 951 are described, but will not be repeated here.

[0089] In order to generate a structure and have according to Figure 11C The depth variations between structures in the contour map 1240 can be determined based on the duty cycle profile 1151 across the entire device 1101. Figure 11Cthe duty cycle of the ion beam 216. The duty cycle profile 1151 shows how the duty cycle of the ion beam 216 gradually increases from a low duty cycle of about 0.1 at the -100 Z position to a high duty cycle of about 0.8 at the +100 Z position. The duty cycle of the ion beam 216 can increase along the duty cycle profile 1151 with a linear slope or a substantially linear slope. As Figure 11C As shown in the contour plot 1240, the depth between structures (e.g., the depth of the trenches) increases as the duty cycle increases along the Z direction. For example, the profile plot 1240 shows seven segments 1211-1217 in which the depth between structures gradually increases from the first segment 1211 to the seventh segment 1217.

[0090] Although Figure 11C The illustrated contour plot 1240 shows segments with different discrete depths, but the depth of the segments 1211-1217 can gradually change between adjacent segments (and within a segment) as the duty cycle changes as shown by the duty cycle profile 1151 in Figure 11D As also noted above, changing the duty cycle of the ion beam 216 is just one way to change the depth between structures. For example, in other embodiments, the time that the ion beam 216 is focused on different portions of the device 1101 can be varied while using a constant duty cycle to form the structures and have varying depths between structures. In other embodiments, the power (e.g., voltage and / or current) applied to generate the ion beam 216 can be varied to generate Figure 11C the depth variations shown in the contour plot 1240.

[0091] Figure 12 is a process flow diagram for a method 1200 for forming the device 1101 shown in Figure 11A Referring to Figure 2A , Figure 3 , Figure 10 , Figures 11A-11D and Figure 12 the method 1200 is described.

[0092] The method 1200 begins with performing the method 1000 described above with reference to Figure 10 Although the method 1000 is repeated at the beginning of the method 1200, there are some differences that are worth noting. The method 1000 is performed on the device 900, while the method 1200 is performed on the device 1101. For clarity, the operations of the method 1000 are repeated here to clarify how the method 1000 is performed on the device 1101 as part of the method 1200.

[0093] At block 1002, the device 1101 is positioned at a first rotation angle φ1 in the path of the ion beam 216 on the platform 206 (Figure 2A It can be determined based on the second ion beam angle θ (see...). Figure 2A ) and the tilt angle θ' required for the structure formed on device 1101 (see, for example) Figure 9C According to the rotation angle equation [φ1=cos -1 [(tan(θ') / tan(θ))] determines the first rotation angle φ1. In some embodiments, the notch 907 can be used to align the device 1101 to position it at the first rotation angle φ1.

[0094] In block 1004, at the beginning of the first time period, when device 1101 is positioned at a first rotation angle φ1 between ion beam 216 and grating vector (e.g., grating vector 308) (also referred to as the first vector), ion beam 216 is applied to expose grating material 212 (first material) disposed across the YZ plane (first plane) to ion beam 216 at a second ion beam angle θ relative to the surface normal 218 of substrate 210, to form structures in grating material 212 (first material). The grating vector (e.g., grating vector 308) (first vector) is perpendicular to the direction in which the first plurality of structures extend across the YZ plane (first plane). The structures are formed having a tilt angle θ' relative to the surface normal 218 of device 1101. Although not required, the first rotation angle φ1 shown is consistent with the above reference. Figure 9A The rotation angle φ1 described is the same. Therefore, the tilt angle θ' of the structure formed on the device 1101 at frame 1002 is formed to have the same as... Figure 9C The tilt angle θ' of the structure 906 shown is the same angle. In one embodiment, the ion beam 216 can be initially guided to the bottom seventh segment 9172, for example, with Figure 11B The -100Z position shown is aligned.

[0095] In box 1006, the ion beam 216 can be progressively guided to different portions of device 1101. For example, the ion beam 216 can progressively expose the grating material of the bottom segments 9172-9122 of device 900, followed by the central first segment 911, and then the top segments 9121-9171. The duty cycle of the ion beam 216 can be... Figure 11D The duty cycle profile shown in Figure 951 varies as shown to produce a structure and has a certain degree of variation according to the duty cycle profile shown in Figure 951. Figure 11B The contour plot 940 shows the depth between varying structures. In some embodiments, the ion beam 216 can be scanned in the Z direction over the entire device 1101 using a duty cycle varying according to the duty cycle profile 951, and the device 1101 can be mounted on a fixed platform 206. In other embodiments, the device 1101 can be translated in the Z direction to expose different segments to the ion beam 216.

[0096] At block 1208, the device 1101 is positioned on the platform 206 at a second rotation angle φ2 between the ion beam 216 and the grating vector (first vector) of the structure during a second time period. The second rotation angle φ2 can be a negative angle of the first rotation angle φ1. The second rotation angle φ2 can also be described as being congruent with the first rotation angle φ1. In some embodiments, the grating vector (see, e.g., grating vector 308 of Figure 3 ) can be aligned with the notch 907 (see Figure 9A ). In these embodiments where the notch 907 is aligned with the grating vector, the device 1101 can be positioned at the first rotation angle φ1 relative to the notch 907 during block 1002 of the method 1200 and then positioned at a negative of the first rotation angle φ1 (i.e., the second rotation angle φ2) at block 1208. For example, with reference to Figure 11B , Figure 11C , at block 1002 of the method 1200, the device 1101 can be positioned at +55° and at block 1208, the device 1101 can be positioned at -55°. Positioning the device 1101 at the second rotation angle φ2 (which is a negative angle of the first rotation angle φ1) results in a structure on the device 1101 having the same tilt angle θ' as the structure that results when the device 1101 is positioned at the first rotation angle φ1.

[0097] At block 1210, at the beginning of the second time period, while the device 1101 is positioned at the second rotation angle φ2, the ion beam 216 is applied to expose the grating material 212 to the ion beam 216 at a second ion beam angle θ relative to the surface normal 218 of the substrate 210 to form a structure in the grating material 212. The structure is formed to have a tilt angle θ' relative to the surface normal 218 of the device 1101. In one embodiment, the ion beam 216 can be initially directed to the first segment 1211, e.g., aligned with the -100Z position shown in Figure 11C .

[0098] At block 1212, the ion beam 216 can be incrementally directed to different portions of the device 1101. For example, the ion beam 216 can be incrementally exposed to the grating material of segments 1211-1217, starting with the first segment 1211 and ending with the seventh segment 1217. In some embodiments, the ion beam 216 can be scanned in the Z direction according to the varying duty cycle of the duty cycle profile 1151 across the entire device 1101, which can be disposed on a stationary platform 206. In other embodiments, the device 1101 can be translated in the Z direction to expose different segments to the ion beam 216.

[0099] The duty cycle of the ion beam 216 can vary as shown in the duty cycle profile 1151 of Figure 11D to produce the structure and have the tilt angle θ' according toFigure 11C The contour plot 1240 shows the depth between varying structures. Note that, as mentioned above, contour plot 1240 illustrates the depth between structures on the previously unexposed grating material. Furthermore, Figure 11A The contour plot 1140 shows the depth between structures obtained by combining the first exposure according to the first duty cycle profile 951 (i.e., boxes 1002-1006 of method 1200) with the second exposure according to the second duty cycle profile 1151 (i.e., boxes 1208-1212 of method 1200).

[0100] like Figure 11B and 11C The exposure of grating material 212 from the -100Z position to the +100Z position, as shown, results in some portions of grating material 212 being exposed twice, while other portions of grating material 212 are exposed only once. For example, when... Figure 11B When the device is positioned with the first rotation angle φ1, the central portion 1181 of the grating material 212 (as shown) Figure 11A ) exposed to ion beam 216, and when as Figure 11C When the device 1101 is positioned with the second rotation angle φ2, the central portion 1181 of the grating material 212 (as shown) Figure 11A ) exposed to ion beam 216. Conversely, when as Figure 11B When the device is positioned with the first rotation angle φ1 as shown, the first part 1191 of the grating material 212 ( Figure 11A ) exposed to ion beam 216, but when as Figure 11C When the device 1101 is positioned at the second rotation angle φ2, the first part 1191 of the grating material 212 (shown) Figure 11A Not exposed to ion beam 216. Similarly, when such Figure 11B When the device is positioned with the first rotation angle φ1 as shown, the second part 1192 of the grating material 212 ( Figure 11A Not exposed to ion beam 216, but when as Figure 11C When the device 1101 is positioned at the second rotation angle φ2, the second part 1192 of the grating material 212 (shown) Figure 11A The grating material 212 is exposed to the ion beam 216. By varying the exposure of the grating material 212 to the ion beam 216 between regions exposed twice (e.g., the central portion 1181) and regions exposed once (e.g., portions 1191, 1192), additional control over the depth profile of the structure produced by method 1200 can be allowed relative to the results of processing using only one exposure or only two exposures.

[0101] Method 1200 is described as using a first duty cycle profile 951 for a first exposure (i.e., blocks 1002-1006 of method 1200) and a second duty cycle profile 1151 for a second exposure (i.e., blocks 1208-1212 of method 1200). However, benefits can be obtained by using two exposures at two rotation angles (e.g., a first rotation angle φ1 and a second rotation angle φ2) even when the duty cycle is constant over a portion of the grating material. For example, if two exposures are performed using the same duty cycle of ion beam 216 over central portion 1181, the roughness of the sidewalls of the structures (e.g., the fins of one or more gratings) can be reduced (i.e., the sidewalls can be made smoother). For example, referring to FIG. 11, if the first exposure is performed at a first rotation angle φ1 and the second exposure is performed at a second rotation angle φ2, the roughness of first surface 901 and second surface 902 can be improved by performing two exposures at the same duty cycle. Such double exposure processing at the same duty cycle can also provide benefits when variable depths between structures are not needed. For example, if a first exposure performed at a first rotation angle φ1 removes grating material 212 down to etch stop layer 211 (FIG. 10), a second exposure performed at a second rotation angle φ2 (i.e., a negative angle of the first rotation angle φ1) can improve the roughness of the sidewalls of the structures without affecting the depths between the structures. Figure 9C For example, referring to FIG. 11, if the first exposure is performed at a first rotation angle φ1 and the second exposure is performed at a second rotation angle φ2, the roughness of first surface 901 and second surface 902 can be improved by performing two exposures at the same duty cycle. Such double exposure processing at the same duty cycle can also provide benefits when variable depths between structures are not needed. For example, if a first exposure performed at a first rotation angle φ1 removes grating material 212 down to etch stop layer 211 (FIG. 10), a second exposure performed at a second rotation angle φ2 (i.e., a negative angle of the first rotation angle φ1) can improve the roughness of the sidewalls of the structures without affecting the depths between the structures. Figure 2A

[0102] While the foregoing is directed to examples of the present disclosure, other and further examples can be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the following claims.​

Claims

1. A method of forming a structure of optical devices, comprising the steps of: exposing a first material disposed across a first plane on a first substrate to an ion beam during a first time period to form a first plurality of structures in the first material, the ion beam directed to the first material at an ion beam angle Θ relative to a surface normal of the first substrate, wherein during the first time period, the first substrate is positioned at a first angle of rotation φ1 between the ion beam and a first vector of the first plurality of structures, the first vector extends in a direction normal to the first plurality of structures across the first plane, during the first time period, the first material is incrementally exposed to the ion beam along a first direction, and the exposure of the first material to the ion beam varies along the first direction to produce a depth variation among the first plurality of structures in the first direction, and exposing the disposed first material to the ion beam during a second time period to modify the depth of at least some of the first plurality of structures, wherein during the second time period, the first substrate is positioned at a second angle of rotation φ2 between the ion beam and the first vector of the first plurality of structures, the second angle of rotation φ2 is a negative angle of the first angle of rotation φ1.

2. The method of claim 1, wherein the first plurality of structures are formed to have a first tilt angle θ1' relative to the surface normal of the first substrate, The first rotation angle φ1 is chosen by the equation φ1 = cos -1 (tan(θ1') / tan(θ)) and the second rotation angle φ2 is chosen by the equation φ2 = cos during the second time period, the depth of the first plurality of structures is modified while maintaining the first tilt angle θ1' of the first plurality of structures.

3. The method of claim 1, wherein a duty cycle used to generate the ion beam varies for different segments of the first material to produce the depth variation among the first plurality of structures as the first material is incrementally exposed to the ion beam along the first direction.

4. The method of claim 1, wherein a time of exposure to the ion beam varies for different segments of the first material to produce the depth variation among the first plurality of structures as the first material is incrementally exposed to the ion beam along the first direction.

5. The method of claim 1, wherein a power used to generate the ion beam varies for different segments of the first material to produce the depth variation among the first plurality of structures as the first material is incrementally exposed to the ion beam along the first direction.

6. The method of claim 1, wherein the first substrate is positioned at the first angle of rotation φ1 on a substrate support.

7. The method of claim 6, further comprising the steps of removing the first substrate from the substrate support; positioning a second substrate on the substrate support; and exposing a second material disposed across a second plane on the second substrate to the ion beam to form a second plurality of structures in the second material, the ion beam directed to the second material at the ion beam angle Θ, wherein the second substrate is positioned at a third rotation angle φ3 between the ion beam and a second vector of the second plurality of structures, the second vector extends perpendicularly to the second plurality of structures in a direction across the second plane, and the step of positioning the second substrate at the third rotation angle φ3 includes the step of rotating the substrate support relative to an orientation of the substrate support when the first plurality of structures has been formed on the first substrate.

8. The method of claim 7, wherein the second material is incrementally exposed to the ion beam along the first direction, and the exposure of the second material to the ion beam varies along the first direction to produce a depth variation between the second plurality of structures in the first direction.

9. The method of claim 8, wherein a duty cycle used to produce the ion beam varies for different segments of the second material to produce the depth variation between the second plurality of structures as the second material is incrementally exposed to the ion beam along the first direction.

10. The method of claim 7, wherein the second plurality of structures is formed to have a second tilt angle θ2' relative to a surface normal of the second substrate, and The third rotation angle φ3 is chosen by the equation φ3 = cos -1 (tan(θ2') / tan(θ)).

11. A method of forming structures of an optical device, comprising the steps of: exposing a first material disposed on a substrate across a first plane to an ion beam during a first time period to form a first plurality of structures in the first material, the ion beam directed to the first material at an ion beam angle θ relative to a surface normal of the substrate, wherein the substrate is positioned at a first rotation angle φ1 between the ion beam and a first vector of the first plurality of structures during the first time period, and the first vector extends perpendicularly to the first plurality of structures in a direction across the first plane; and exposing the disposed first material to the ion beam during a second time period, wherein the substrate is positioned at a second rotation angle φ2 between the ion beam and the first vector of the first plurality of structures during the second time period, and the second rotation angle φ2 is a negative angle of the first rotation angle φ1.

12. The method of claim 11, wherein during the first time period, a first segment of the first material is exposed to the ion beam, during the second time period, a second segment of the first material is exposed to the ion beam, and the second segment includes at least a portion that was not exposed to the ion beam during the first time period.

13. The method of claim 12, wherein the first segment and the second segment share a common portion.

14. The method of claim 11, wherein during the first time period, the first material is incrementally exposed to the ion beam along a first direction, and the exposure of the first material to the ion beam varies along the first direction during the first time period to produce a depth variation between the first plurality of structures in the first direction.

15. The method of claim 14, wherein during the second time period, exposure of the first material to the ion beam varies along the first direction to create a modified depth variation among the first plurality of structures in the first direction.

16. The method of claim 11, wherein during the first time period, the first plurality of structures are formed with a first tilt angle θ1’ relative to a surface normal of the substrate, during the second time period, the first plurality of structures are exposed to modify a depth of at least some of the first plurality of structures while maintaining the first tilt angle θ1’ of the first plurality of structures. The first rotation angle φ1 is chosen by the equation φ1 = cos -1 (tan(θ1') / tan(θ)) and the second rotation angle φ2 is chosen by the equation φ2 = cos 17. The method of claim 11, wherein during the first time period, a duty cycle used to generate the ion beam is varied according to a first profile, and during the second time period, the duty cycle used to generate the ion beam is varied according to a second profile.

18. A method of forming a structure of optical devices, comprising the steps of: during a first time period, exposing a first material disposed on a substrate across a first plane to an ion beam to form a first plurality of structures in the first material, the ion beam directed to the first material at an ion beam angle θ relative to a surface normal of the substrate, wherein during the first time period, the substrate is positioned at a first rotation angle φ1 between the ion beam and a first vector of the first plurality of structures, the first vector extends in a direction across the first plane normal to the first plurality of structures, during the first time period, the first plurality of structures are formed with a first tilt angle θ1’ relative to a surface normal of the substrate, and the second rotation angle φ2 is a negative angle of the first rotation angle φ1, by the equation φ1 = cos -1 (tan(θ1') / tan(θ)) to select the first rotation angle φ1 ; and exposing the first material to the ion beam during a second time period, wherein during the second time period the substrate is positioned at a second rotation angle φ2 between the ion beam and the first vector of the first plurality of structures, wherein during the first time period, a duty cycle used to generate the ion beam is varied according to a first profile, and during the second time period, the duty cycle used to generate the ion beam is varied according to a second profile.

19. The method of claim 18, wherein during the first time period, a first section of the first material is exposed to the ion beam, and during the second time period, a second section of the first material is exposed to the ion beam, the second section includes at least a portion that was not exposed to the ion beam during the first time period.

20. The method of claim 19, wherein the first section and the second section share a common portion. ​

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